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%Qk*
LIBRARY
or TI1K
University of California.
GIFT OF"
Pacific Theological Seminary.
erfccessiott 8 4 5 2 Q Cta*
|jl Ciass
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GIFT OF
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Digitized
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FIRST PRINCIPLES
CHEMISTRY,
FOE THE
®st 0f Alleges aifo ££fy»b.
IT
BENJAMIN SILUMAN. Jr.. M.A.. M.D.
rmontssoR in tili ooixboi or cbbmistst as appubd to tm a*t». akp or ummaAL
CHIMISTBT AKD TOXlCOlAQT Of VOXntXtLXM MITMaTT,
BSttf) Jour Sii^l^SBsP*>il4ik^rft Wttftrattoiw.
rtF THE
UNIVERSITY
FORTY-EIGHTH EDITION.
REWRITTEN AND ENLARGED.
PHILADELPHIA:
H. C. PECK & THEO. BLISS.
1860.
Digitized
byGoogk
In preparation by Professor BfllfnuTi,
An Elementary Treatise on Natural Philosophy, for Colleges
and Schools.
Entered aeoording to the Act of Congress, in the year 1862, by
H. a PECK A THEO. BLISS,
in the Clark's Office of the District Conrt of the Eastern .Pktriet ot
PtmntylTania.
NvcasormD bt l. johwbok and a*
VEBJ&VSBLL.
PRINTED bt a I
Digitized
byGoogk
TO
itnjamin Silliman,
fob nm tears professor of chemistry nc talk collbbb,
Ii)i$ DolqftK»
DBSIOKED TO PROMOTE THAT SCIENCE, Tf WHICH HE
HAS DEVOTED HIS LIFE,
IB RESPECTFULLY DEDICATED,
THK AUTHOR.
.84529
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PREFACE TO THE THIRD REVISED EDITION.
Ddbuto the fire years which hare passed since the second edition of
this work was prepared, intense activity has prevailed in all depart-
ments of chemical research. Any attempt to preserve the stereotype
plates of that edition in the present was found to he quite impracti-
cable. The whole work has been entirely revised, rewritten, and so far
rearranged, as experience has shown to he desirable. Some parts have
been enlarged, and some have been contracted, so that on the whole the
size of the volume remains much as before. A great number of new
illustrations have been added, more than doubling the number in the
former editions. A considerable number of wood outs have been taken
from Begnault's excellent Chun de Chimie, and many new ones have been
drawn from the author's apparatus. Every important fact, formula, and
number in the work has been carefully compared with the most recent and
valued authorities. The changes made in the atomic weights of element-
ary substances, during the last five years, have been numerous and im-
portant; and in most oases these changes have added simplicity to the
science. The new facts and principles gleaned in no inconsiderable num-
bers for this edition, have been woven into the text in such a manner as
to present, it is hoped, an uniformity of design.
In vthe Organic Chemistry, greater simplicity and unify has been
giver. U> the principles involved in the almost unwieldy mass of facts
which have accumulated so rapidly during the last ten years. The
author has again to acknowledge his obligations to his friend and former
associate, Mr. Hunt, for his lucid and original exposition of this part of
the subject
The adoption of this work by many of the first seminaries of learning
in this country, is a gratifying evidence to the author that his design
has been appreciated; and he trusts that those who gave their confi-
dence to the two first editions, will find the present one, in many import-
ant respects, superior to them.
Hiw Havsh, September 80, 1862.
OF THE
UNIVERSITY
S?UFORt*\^
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FROM THE PREFACE ^TO THE FIRST EDITION.
The object of this work is sufficiently indicated by iti title. It hai
grown out of the exigencies of teaching, and has been received as the
text-book in the public lectures at Tale College.
It is important that a work of this kind should contain only such
matter as is actually taught to a class by recitations and lectures.
All fulness beyond this is unavailable to either teacher or pupil, and
serves often to embarrass the one and discourage the other. This is,
perhaps, the reason why several works, otherwise excellent, have failed
to answer the purpose for which they were written. The science of
Chemistry has now reached the point where its first principles can be
presented by the teacher with almost mathematical precision.
Chemistry has attractions of an economical and experimental charac-
ter, which will always secure for it a place in every system of educa-
tion. Without wishing to diminish its claims to attention on these
grounds, the author urges the paramount advantages possessed by his
favourite science, as a study peculiarly fitted to train the mind to a me-
thodized and logical habit of thought. If nothing more is to be derived
from its study than the entertainment offered by brilliant phenomena,
and a knowledge of convenient economical processes, the pupil will fail
of its most important advantage. The beautiful philosophy, the perspi-
cuous nomenclature, and lucid method of modern chemistry, are so ob-
vious that they cannot fail to awaken the attention of every intelligent
pupil, and carry him on his course of intellectual culture with rapid
progress.
The author has consulted all the best authorities within his reach,
both in the standard systems of England and France, and in the scien-
tific journals of this country and Europe. The works of Daniell, Gra-
ham, Brande, Kane, Fownes, Gregory, Faraday, Mitscherlich, Berselius,
Dumas, LieMg, and Gerhardt, have all been used, as also the treatises
of Dr. Hare and Prof. SiUiman.
The Organic Chemistry is presented mainly in the order of Liebig in
his Traite de Chimie Organique. The author takes pleasure in ac-
knowledging the important aid derived in this portion of the work
from his friend and professional assistant, Mr. TfiOMAS S. Hvht, whose
familiarity with the philosophy and details of Chemistry, will not fail to
make him one of its ablest followers. The labour of compiling the Or-
ganic Chemistry has fallen almost solely upon him.
If it shall be found to meet the wants of both teachers and pupils, and
to promote the progress of Scientific Chemistry in this country, the
author will feel that he has not laboured in vain.
Nsw H&vnr, December 80, 1840.
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TABLE OF CONTENTS.
PART L
PHTSICS.
rioa
INTRODUCTION
Sources of Natural Know-
ledge 13
Observation 14
Divisions of Natural Science. 15
MiniR.- General Properties
of Matter 16
Mechanical Attraction 17
Molecules 18
Three States of Matter— Co-
hesion 19
Capillary Attraction 21
Exosmose and Endosmose..... 23
Mechanical Properties of the
Atmosphere 23
Air-pumps 24
Law of Mariotte 26
Barometer , 28
Weight of Atmosphere 30
Weight and Specific Gravity 31
Hydrometer...* 33
Crystallization. — Nature of
Crystallization 36
Polarity of Molecules 37
Crystalline Forms 9%
Measurement of Crystals 41
Light. — Sources and Nature... 43
Undulations 44
Properties of Light 46
Reflection 47
Simple Refraction 48
Analysis of Light 50
Double Refraction 52
Polarisation 53
Chemical Rays 55
Phosphorescence 66
Heat. — Sources » 6T
Properties 68
Communication of Heat 69
Radiation 60
Conduction « . 61
Vibrations 62
Convection , 65
Transmission of Heat 66
Expansion 69
Thermometer 75
Pyrometer 78
Capacity for Heat 79
Change of State produoed by
Heat 81
Liquefaction, Latent Heat... 82
Vaporization 85
Boiling 86
Spheroidal State 87
Boiling in vacuo 89
Elevation of Boiling-points
by Pressure ..» 90
Steam Engine 92
Evaporation 93
Density of Vapors 94
Dew-point 95
Hygrometers 96
Diffusion and Effusion of
Gases 97
Liquefaction and Solidifica-
tion of Gases 98
Electricity * 100
Magnetic Electricity, Mag-
netism 101
Electrical Machines 107
Statical Electricity 108
Electroscopes 108
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CONTENTS.
PAG*
Theories of Electricity. ,- 110
Leyden Jar Ill
Eleotrophoruf 113
Galvanism 114
Voltaic Pile 115
Ohm's Law 118
Batteries 120
Smee's Battery 121
Daniell's Battery 122
Grove's Battery. » 123
Bunsen's Battery 124
Electrical Light 125
PMl
Electro-Magnetism .. » 127
Amperes Theory- 128
Electro-Magnets. 130
Electromagnetic Telegraph.. 131
Pro£ Henry's Discoveries.... 134
Magneto-Electricity 137
Thermn-Electricity 139
Animal Electricity 140
Electrochemical Decomposi-
tions 142
Faraday's Researches 143
Electrotype. M 148
PART n.
CHEMICAL PHILOSOPHT.
elements ahd thbib laws of
Combination. 150
. Table of Elementary Bodies 152
Laws of Combination 153
Chemical Nomenclature and
Symbols 155
Combination by Volume 161
Specific Heat of Atoms 162
Isomorphism and Dimorph-
ism 162
Chemical Affinity 164
PART ni.
INORGANIC CHEMISTRY.
Classification of Elements 160
Oxygen 169
Management of Gases 174
Chlorine 176
Compounds of Chlorine with
Oxygen 180
Bromine 183
Iodine 184
Fluorine 186
Sulphur. 187
Sulphurous Acid 190
Sulphuric Acid 192
Chlorids of Sulphur 187
Selenium 198
Tellurium ^ 199
Nitrogen 199
The Atmosphere 201
Compounds of Oxygen and
Nitrogen 203
Nitric Acid M.... 204
Protoxyd of Nitrogen 206
Nitric Oxyd 208
Phosphorus 210
Compounds of Phosphorus
with Oxygen 213
Carbon..... 216
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CONTENTS.
9
FACE
Carbonic Acid. 220
Carbonic Oxyd 223
Bisulphuret of Carbon 224
Cyanogen. 225
Silicon 227
Silica 228
Fluorid of Silicon 229
Boron .... 229
Boraoio Acid — 230
Hydrogen 231
Water 236
Eudiometry 239
Action of Platinum with Hy-
drogen and Oxygen 242
Oxyhydrogen Blowpipe. 244
History of Water 246
Peroxyd of Hydrogen 249
Hydracids 250
Chlorohydrio Acid 251
Bromohydrio Acid « 255
Iodohydrio Acid 256
Fluohydrio Acid 257
Solphydrio Acid 258
Compounds of Hydrogen with
class HX 261
Ammonia 262
Phosphuretted Hydrogen 265
Compounds of Hydrogen with
the Carbon group 266
Marsh Gas 267
defiant Gas 268
Combustion and Structure of
Flame 272
Safety Lamp 276
Metallic Elbiixnts
General Properties of Metals 278
Metallic Veins. 278
Physical Properties of Metals 280
Chemical Relations of the
Metals 283
Salts 285
Potassium 288
Compounds of Potassium..... 291
Potash 292
Salts of Potash 295
Sodium M 300
Caustic Soda, Common Salt. 301
Sulphate of Soda 302
Carbonate of Soda 304
Nitrateof Soda 305
PAOl
Phosphates of S% da 306
Borax. 307
Lithium 307
Ammonium ~ 398
Compounds of Ammonium... 309
Barium 311
Strontium - 313
Calcium. 314
Gypsum 316
Carbonate of Lime 317
Magnesium 319
Sulphate of Magnesia 320
Aluminum 321
Alums M 322
Silicates of Alumina 323
Manufacture of Glass 323
Pottery 327
Glncinum, Yttrium, Zirco-
nium, Thoria 328
Manganese « 328
Iron 330
Reduction of. 334
Chromium 336
Nickel 339
Cobalt 340
Zinc * 341
Cadmium 342
Lead. 343
Uranium —.. 345
Copper 345
Vanadium, Tungsten, Colum-
bium, Titanium, and Mo-
lybdenum 348
Tin 349
Bismuth 350
Antimony 352
Arsenic 354
Detection of Arsenic in poi-
soning 357
Mercury 361
Calomel 364
Salts of Mercury 366
Silver 366
Cupellation 368
Gold 371
Palladium 372
Platinum 373
Iridium, Osmium 375
Rhodium, Ruthenium 376
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10
CONTENTS,
PART IV.
ORGANIC CHEMISTRY.
PAQB
Introduction 377
Nature of Organic Bodies.... 377
Laws of Chemical Trans-
formations 370
* Equivalent Substitution 380
Substitutions by residues 384
Sesqui-salts, Direct Union... 385
On Combination by Volumes 386
Density of Carbon Vapor..... 386
On the Law of the Divisibility
of Formulas 387
On Isomerism 388
On Chemical Homologues.... 389
Temperature of Ebullition... 390
Analysis or Organic Sub-
stances 390
Density of Vapors 395
Water 396
Ammonia. 397
Carbonic Acid 400
Sugar, Starch, and Allied
Substances.... 401
Cane, Grape Sugars 401
Sugar of Milk, Mannite 402
Products of the Decomposi-
tion of the Sugars 403
The Vinous Fermentation... 403
Lactic Acid.. 405
Gum , ~ 407
Starch 407
Woody Fibre 409
Xyloidine, Pyroxyline, Gun-
cotton 411
Transformation of Woody
Fibre 412
Destructive Distillation of
Wood. 413
Kreasote , 413
Wood-tar, Paraffin, Coal-tar 414
Petroleum..... 415
Alcohols, Vinol 415
Action of Acids upon Alcohol 417
Ethers 419
Nitric, Nitrous, Perchloric
Ethers 420
Sulphovinic Acid 420
Silicic Ethers, defiant Gas... 425
Products of the Ozydation of
Alcohol 426
Chloral, Sulphur Aldehyde... 428
Acetic Acid 429
Acetates, Acetate of Potash... 430
Acetate of Lead 431
Acetate of Copper, Chlorace-
ticAcid 432
Acetic Ether 433
Mbthol 434
Wood-spirit, Pyroxylio Spi-
rit, Methylio Alcohol 434
Sulphomethylio Acid. 435
Oxydation of Methol 437
Amylol, Amylio Alcohol 438
Oxydation of Amylol 439
Spermaceti, Wax.... 440
Glycerids 441
Soaps, Butyric Acid „. 442
Phoeenine, Enanthylie and
( Pelargonic Acids 443
Oleine, Palmatine, Marga-
rine, Stearine 444
Fatty Acids 446
Alkaloids of Alcohol Series 448
Ethamine, Methamine, Amy-
lamine .... 449
Triethamine 450
Bitter-Almond Oil 452
Benzoilol 452
Chlorinized Benzoilol, Hy-
drobenxamide 453
Benzoic Acid 454
Benzen 455
Salicylol 458
Other Essential Oils 459
Oil of Cinnamon 459
Oil of Turpentine..... 459
Oils of Juniper, Pepper, Ca-
raway, Parsley, Ac 460
Camphor, Borneo Camphor... 461
Resins 462
Caoutchouc, Gum-Elastic... 462
Gutta Percha 463
Vegetal Acids 463
Oxalic Acid 464
Tartaric Acid 465
Racemic Acid, Malic Acid.... 467
Citric Acid 469
Tannic Acid, Tannin 469
Gallic Acid M 470
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CONTENTS.
11
Vegetal Alkaloids 471
Alkaloids of Cinchona 472
Alkaloids of Opium 473
Morphine, Codeine, Naroo-
tine M 474
Strychnine, Bruoine, Pipe-
riue 475
Theine, Caffeine, Theobro-
mine, Solanine 476
Veratrine, Aconitine, Sangui-
narine, Emetine, Nico-
tine, Conine 477
Amygdaline, Emulsine - 478
Salicine, Saligenine, Salire-
tine, Helioine 479
Populine, Phloridxine 480
Coloring Matters. 481
Leeanorine « 481
Orcine, Evernio Acid, Litmus 482
Xanthine, Alizarine, Madder
lake „ 483
Carthamine, Hematoxyline. 483
Quercitrine, Luteoline, Mo-
rine, Chlorophyll 483
Indko 484
Sulphindigotic and Sulpho-
purpuric Acids, Saxon
Blue 485
Isatine, Anthranilio Acid..... 485
The Cyanic Compounds 486
Hydrocyanic Acid 486
Cyanid of Potassium 488
Cyanid of Ammonium. 488
Cyanogen 488
Cyanates 480
Urea 490
Sulphooyanates - 491
Sulphocyanio Acid 491
Cyanoxsulphid, Mellon 492
Polycyanids 492
Perchloric Trioyanid, Per-
chlorio Dicyanid, Cya-
nuric Acid 493
Melamine, Ammelid, Amme-
line 494
Fulminates 494
Cyanethine 495
Alanine, Vinic Urea 496
Allophanio Acid... „ 496
Trigenio Acid 497
Cyaniline, Melaniline, Cy-
ameline, Cyanbarma-
line 497
PAOS
Ferroeyanids „. 498
Yellow Prussiate of Potash... 499
Ferrocyanic Acid, Prussian
Blue 500
Ferricyanid8, Bed Prussiate
of Potash 500
Nitroprussids 501
Cobalticyanids 502
Platinooyanids, Argentooya-
nid of Potassium 503
Aeids of the Urine and Bile.. 503
Hippuric Acid, GlycolL 504
Uric, or Lithic Acid. 505
Allantoin, Alloxan. 506
Alloxantine, Dialurio Acid... 507
Uramile, Murexid. 508
Parabanic Acid, Amalio Acid. 509
Cholio, Cholalic Acids 509
Choloidic Acid, Taurine, Hy o-
cholalicAcid 510
Biliary Calculi 510
Nutbitivi Substances con-
tainino Nitrogen 511
Protein, Fibrin, Albumin, Ca-
sein 511
Gluten, Vegetable Albumin.. 512
Legumin 512
Leuoin, Tyrosin 514
Yeast..'. 516
Gelatin 517
The Blood 518
Blood Globules 518
Hematosine 519
Seroline 520
Flesh Fluid 522
Creatine, Creatinine 522
SarcOsine, Inosinic Acid 523
Saliva, Pancreatic Juice 523
Gastric Juice. 524
Pepsin, Bile 524
Chyle, Urine 525
Microcosmio Salt 526
Milk 527
Eggs 528
The Brain and Nervous Sub-
stance 528
Bones 529
Nutrition op Plants and op
Animals 530
Food of Plants 531
Manures ; 532
Digestion 534
Respiration 535
Vital Heat 537
Appendix 539
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FIRST PRINCIPLES
CHEMISTRY.
PART I— PHYSICS.
INTRODUCTION.
1. Our knowledge of nature begins with experience.
While this teaches us that like causes, under similar cir.
cumstances, produce like effects, we recognise also, as insepa-
rable from our experience, the great principle that every event
must have a cause. Man, " as the priest and interpreter of
nature," seeks to extend his experience by experiment.
Every experiment is but a question addressed to nature, ask-
ing for an increase of knowledge; and if we question her
aright, we may be sure of a satisfactory answer.
2. Observation instructs us in a knowledge of the external
forms of nature, and we thus acquire our first impressions of
the various departments of Natural History. Our knowledge
would, however, be very limited, without a constant effort
to extend our experience by experiment. The nations of
antiquity excelled greatly in many branches of human know-
ledge, and their skill in the arts of design remains unequalled.
Their ignorance, however, of natural phenomena, and the
(aws by which they are governed, was remarkable; because
they overlooked the true connection between cause and effect.
1. What if the beginning of our knowledge of nature? What great
principle do we recognise in connection with experience ? What is an
experiment ? 2. What does obserration teach ? How does it extend out
knowledge?
_84529
14 INTRODUCTION.
The ancient philosophy abounded in plausible arguments
regarding those natural phenomena which could not fail to
arrest the attention of an intelligent people ; but its reason-
ings were based on an d priori assumption of a cause, and
not upon an inductive inquiry after facts and their connec-
tions. It failed to apply iteelf to the careful collection and
study of facts in order to science. Facts in nature are th&
expression of the Divine will in the government of the phy-
sical world. The universe of matter is made up of nets,
which, observed,, traced out, and arranged, lead us to the
knowledge of certain laws and forces which proceed directly
from the mind of God. These are the " laws of nature :
science is but the exposition of them and of science based
upon such grounds, the ancient philosophy was completely
ignorant.
3. It is important to distinguish that knowledge which is
purely intellectual in its character, from that which results
from observation and experience. Speaking of this subject,
one of the most learned of living philosophers remarks : "A
clever man, shut up alone, and allowed unlimited time, might
reason out for himself all the truths of mathematics, by pro-
ceeding from those simple notions of space and number, of
which he cannot divest himself without ceasing to think ; but
he could never tell, by any effort of reasoning, what would
become of a lump of sugar if immersed in water, or what
impression would be produced on the eye by mixing the
colors yellow and blue." — (Eerschel.) We may, however,
with propriety doubt, whether there is any knowledge or
philosophy so purely intellectual, or absolute, that it does
not imply some previous recognition of physical facts.
4. The observation of facts forms only the foundation of
science, — an isolated fact has no scientific value. The know-
ledge of physical laws deduced from the study of observed
facts will enable the philosopher to foretell the result of the
possible combination of those laws, and to assign reasons for
apparent departures from them. In this way discoveries are
predicted and detailed ; observation is anticipated, and called
Characterize the ancient philosophy. How did it fail? What art
facts ? What are laws of nature ? What is science ? 3. What convenient
distinction is named? What remark is quoted in illustration of this?
4. What is said of observation? What of an isolated fact? What
does a knowledge of natural laws enable the philosopher to do?
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INTRODUCTION. 15
on to verify tbe alleged discovery. The perturbations of the
planet Uranus indicated the existence of some body in space
heretofore unknown. When Le Verrier had reconciled these
disturbances with the supposed influence of a new planet,
and determined its elements of motion, he had as truly dis-
covered the remote, sphere, as when the German astronomer!
by pointing his telescope to the precise place in the heavens
which Le verrier had designated, announced to the world
that the stupendous prediction was verified by observation.
In like manner, a familiarity with chemical laws enables the
chemist to foretell the result of combinations which he has
never investigated, and in some cases to assign with confi-
dence the constitution of bodies which he has never ana-
lyzed.
5. Our knowledge of Natural Science is conveniently
classified under the three great divisions of Natural History,
Physical Philosophy, and Chemistry. The first teaches us
the characters and arrangement of the various forms of ani-
mal and vegetable life and minerals, giving origin to the
sciences of Zoology, Botany, and Mineralogy. Physical
Philosophy explains the forces by which masses of matter
are governed, and unfolds the laws of Light, of Electricity,
and of Heat.
Chemistry teaches us the intimate and invisible constitu-
tion of bodies, and makes known the compounds which may
be formed by the union of simple substances, the laws
of their combination, and the properties of the new com-
pounds. It investigates the forces resident in matter, and
which are inseparable from our idea of molecular action, —
forces whose play produces the phenomena of Light, of
Heat, and of Electricity. Chemistry also unfolds the won-
derful operations of animal and vegetable life, so far as their
functions depend upon chemical laws, as in die processes of
respiration and digestion, giving the special department of
Physiological Chemistry.
Illustrate this in case of the perturbations of Uranus. 5. How is out
knowledge of nature classified? What does the first teach? Physical
philosophy teaches what? Define the province of Chemistry.
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16 MATTER.
I. MATTER.
General Properties of Matter.
6. Experience, founded on the evidence of our senses, con-
vinces us of the existence of matter. We feel the resistance
which it offers to our touch ; we see that it has form, and
occupies space, and hence we say it has extent ; and, lastly,
we attempt to raise it, and we find ourselves opposed by a
certain force which we call weight.
Matter possesses extension, because it occupies some space.
It is impenetrable, because ono particle of matter cannot
occupy the same space with another at the same time. It
has gravity, because it obeys the law of universal attraction.
Whatever, therefore, possesses these three qualities, is
matter.
7. All the changes of which matter is capable may be
referred to one of three great principles or forces, and to
their modifications or combinations. These are Attraction,
Bepulsion, and Vitality.
Attraction is divided into Mechanical and Chemical.
8. Mechanical Attraction is divided into, I. Gravitation,
acting at all distances, and between all masses. 2. Cohesion,
acting between bodies or particles of the same kind only,
and at immeasurably small distances. To this power are
referred all the phenomena of solidification and crystalliza-
tion. 3. Adhesion, acting between bodies of unlike kinds,
at immeasurably small distances, and forming mixed masses.
Chemical Attraction, or Affinity, exists only between mole-
cules or particles of unlike kinds, acts only at immeasurably
small distances, and produces homogeneous masses which
have properties unlike the constituent elements. In a word,
gravity acts on all matter and at all distances. Cohesion
acts only on the same kind of matter at inseosible distancos.
Chemical affinity acts only between unlike particles at in-
sensible distances.
Repulsion is a force seen in the impenetrability of matte*
6. Whence our knowledge of matter? Define its properties. 7. Name
three forces governing matter. 8. Subdivide mechanical attraction.
How is chemical distinguished from mechanical attraction? What of
repulsion ? Define vitality.
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OP MECHANICAL ATTRACTION. IT
and in its power of expansion. It is the antagonist of co-
hesion, or, as it is sometimes called, the attraction of aggrega-
tion. Heat resolves the several forms of mechanical attrac-
tion, and surrenders matter to the dominion of repulsive force,
by which its particles or molecules are widely separated.
Vitality rules superior to all the laws of mechanical and
of chemical attraction, suspending, modifying, or applying
them for the production of those complicated results which
are seen in the organized structures of plants and animals.
9. Such are the great forces to which matter is subject
All the changes resulting from the operation of the forms
of mechanical attraction belong to Physics. Those referable
to vitality fall within the province of the physiologist.
The consideration of the changes produced in matter by
the exertion of affinity, or chemical attraction, constitutes
the appropriate business of the chemist.
All that relates therefore to physics might be properly
dismissed from a manual of chemistry ; but it is usual for
the chemical student to devote a share of his attention to
those departments of physics, some knowledge of which is>
essential to a correct understanding of chemical phenomena."-
Of Mechanical Attraction.
10. Gravitation is a force measured in any particular case
by weight, whether we speak of a movable mass capablo of
equipoise in our balances or of the weight of the planets as
deduced from their observed motions. It acts at all dis-
tances upon all matter, and is directly as the mass and in-
versely as the square of the distance. The weight of a body
is therefore proportioned to the number of molecules or par-
ticles which it contains.
11. Cohesion, is seen alike in solids, in fluids, and in
gases — three states of matter incident to the equilibrium of
the forces of repulsion and cohesion, and modified by the
laws of heat. Those who regard light, heat, electricity, and
magnetism as imponderable bodies, refer their properties
also to the antagonistic power of repulsion, by which these
manifestations are so controlled that we have no proof of
the existence of mutual cohesion among their particles.
9. What does physics include? 10. How is Gravitation measured t
Define its law. 11. What of Cohesion ?
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18 MATTER.
In the force of cohesion, or attraction of aggregation, at
manifest in solid bodies! we recognise a power which opposes
the division of matter.
12. Divisibility of matter. — The question of the infinite
divisibility of matter has in past times been the subject of
most animated discussions, and until the discoveries of modern
chemistry, no satisfactory solution was reached. We know
that the largest and most solid masses of matter, even en-
tire mountains, may be ground down by mechanical force to
dust so fine that the winds will bear it away, but each mi-
nute particle still occupies some space; and we may imagine
that a great multitude of smaller particles may be formed
from its further division. A grain of gold may be spread
out so thin as to cover 600 square inches of surface on silver
wire, and one ounce, in this manner, be made to cover 1300
miles of such wire. One grain of green vitriol, (sulphate
of iron,) dissolved and diffused in 20 million grains of water,
will still be easily detected by the proper tests. The delicate
perfume of musk and the aroma of flowers are remarkable
examples of minute division in matter.
The organic world also presents us with beautiful ex-
amples of the great divisibility of matter, in the remarkable
forms of animalcules revealed by the microscope, many
millions of which can be embraced in a single drop of water.
Tet each of these inconceivably minute organisms has its
own muscular, digestive, and circulatory systems. How mi-
nute, then, the ultimate particles, of which many myriads
must be contained in each animalcule I
Chemistry has happily resolved the question of infinite
divisibility, by proving that all matter oonsists of certain
particles of definite values, whose relative weights and bulks
may be precisely determined. These particles are called —
13. Molecules,* or Atoms. — Ultimate chemical analysis
has demonstrated that matter consists of many distinct
varieties, called elementary or simple bodies, and that
12. What degree of divisibility exists in matter? Give some illustra-
tions. 13. What is said of molecules?
* Molecule, a diminutive of mole*, a mass. This term is preferable to
'atom* or 'ultimate particle/ as implying no theory, which both the others
do. Atom is from a, privative, and temno, I cut, signifying their supposed
indivisibility.
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THE THREE STATES OF MATTER. 19
these several separate sorts of matter possess each its
own combining quantity, from which it never varies, and
this quantity, called its equivalent, atomic, proportional, or
combining number, is susceptible of accurate determination
by the balance. The molecules of simple bodies are neces-
sarily simple themselves, while the molecules of compound
bodies are, on the contrary, complex. Whatever size these
molecules may possess, they are the centres of all the
forces and qualities whose united effects and activity give
matter its physical or chemical properties. Although we
may never know the absolute weight of any molecule, we do
know with much certainty the relative size and weight of
the molecules of over sixty sorts of simple matter, which che-
mistry has revealed to us. The laws of crystallogeny also
inform us that these molecules have an inherent difference
of form ; some being spherical, while others are ellipsoidal.
Of Cohesion in reference to the three states of Matter,
the Solid, the Liquid, and the Gaseous.
14. Properties of Solids. — It is a distinguishing pro-
perty of solids to have their particles bound together by so
Btrong an attraction as in a great measure to destroy their
power of moving among each other.
No solid, however, not even gold and platinum, which
are the most compact solids known, has its particles of mat-
ter so aggregated as to be incapable of some condensation.
Blows, pressure, or a reduction of temperature, will condense
almost all solids into a smaller bulk. Water may even be
forced through the pores of gold, by very great mechanical
pressure. All solid bodies are, therefore, considered as por-
ous, and their particles are believed to touch each other in
comparatively few points.
Cohesion in solids may be destroyed either by mechanical
violence, as in pulverization ; by solution, as in the case of
saline bodies soluble in water ; or by the agency of heat, as
in the fusion of wax or lead. The mobility of the particles
in solid bodies is shown also in the elasticity, malleability,
ductility, and laminability of many metals, which are among
their most useful properties. Hardness is a quality having
What forms hare the molecules ? 14. What mobility hare particles in
solids ? What of pores in solids ? How may cohesion be destroyed ? \
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20
MATTER.
no relation to the preceding, and is possessed by solids in very
various degrees, and apparently without reference either
to the density or chemical nature of the substances, — for
gold and platinum, among the heaviest of known bodies, are
comparatively soft, while the diamond, which is only about
one-sixth part as heavy as these metals, is the hardest of all
known substances. Cohesive attraction, when once disturbed
by mechanical violence, is not usually brought into exercise
again by mere approach of the separated particles. The
broken fragments of a glass vessel or portion of stone do not
reunite at ordinary temperatures. Nevertheless! we have
some examples of a contrary nature.
If we press together
two smooth surfaces of
lead, clean and bright,
as, for example, the
halves of a leaden
sphere, (fig. 1,) cut
through, they will ad-
here or unite together
so firmly as to require
the power of several
pounds weight to draw
them asunder, as shown
in the annexed figure.
The plates of polished
glass, also, which are
prepared for large mir-
rors, if allowed to rest
together with their sur-
faces in close contact,
have been known to
unite so firmly as to
break before they would yield to any effort to separate them.
In these cases, actual contact of contiguous particles is ef-
fected, and thus the conditions of cohesive attraction are
fulfilled. We may regard the welding of iron and the cohe-
sion of masses of dough or putty as examples of a similar
kind. The casting of metals by voltaic electricity, from cold
solutions of their salts, also affords us elegant examples of
adhesive attraction.
What of hardness ? Gire examples of cohesion at common temperatures.
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THE THREE STATES OF MATTER.
21
15. In fluids, the particles have perfect freedom of mo-
tion among themselves. They are either inelastic liquids,
like water, or elastic gases or vapours, like air and steam.
A gas is a permanent elastic fluid : a vapour is such only io
certain conditions of temperature and pres-
sure. In water we have a familar example of
a body, presenting the three conditions of mat-
ter, in the ordinary changes of the seasons.
Liquids are not completely inelastic, but
are compressible to a very slight extent by
pressure, as is shown in the apparatus of
Oersted, fig. 2. A small glass bulb b, with
a narrow neck, is filled with water lately
boiled, and placed in the glass vessel a, also
filled with water by the funnel g; a metallic
plug h is forced down by the screw k, pro-
ducing any required pressure. A small glo-
bule of mercury in the stem of b by its de-
scent notes the amount of condensation which
the water in b suffers. No change of dimen-
sions in the glass b can happen, because it is
equally compressed from within and without.
In this way the compressibility of water has
been shown to be equal to one part in 22,000
for each atmosphere of 15 pounds pressure.
Alcohol has about half this degree of compres-
sibility; ether about one-third more, and
mercury only about one-twentieth as much.
16. CapUlary attraction is a form of cohesion seen in
liquids. If a tube with a very fine bore, and open at both
ends, is immersed in water, it will be observed that the
liquid rises, as seen in fig. 3, to a certain
elevation in the tube, and to a less degree
also on the outer surface. In mercury, (fig.
4,) on the contrary, which does not moisten
the glass, there is a depression of the column
in the tube, and the surfaces of the mercury
are- convex. The height to which a fluid Fig. 3. Fig. 4.
will rise in a tube by capillarity is inversely as the diameter
Pig. 2.
15. How are the particles in fluids? Are fluids elastic? Illustrate it
by the case of water? 16. What is capillarity? What relation has dia-
meter to capillarity?
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22
MATTER.
Fig. 6.
of the tube. Two plates of glass held as in fig. 5, opening
like the leaves of a book, and their lowet
edges immersed in a fluid, show this law
by the curve which the liquid assumes.
By the power of capillary attraction, the
wick supplies fuel to the lamp or candle.
Plugs of dry wood driven into holes bored
in granite, and then saturated with water,
swell so much by the water taken into their
I pores by capillarity that the rocks are split
open. Even a bar of lead or tin, bent like the
letter U and placed by one end in a vessel
of mercury, will, after some time, convey it out of the vessel
drop by drop. Two small balls, one of wax and one of cork,
(fig. 6,) thrown upon the surface of
water, manifest repulsion at first,
> for the water not wetting the wax
while it does the cork, causes an
elevation about the latter, from
which the former, so to speak, rolls off, and the balls sepa-
rate in the direction of the arrows. Two balls of cork, for s
like reason, attract one another. Hence the familiar fact
that chips on the surface of quiet water always crowd to-
gether, and gather about a log or larger body on the surface.
The wetting of surfaces by a fluid is perhaps a sort of chemi-
cal affinity. Iron, glass, the skin, or a piece of wood are
not wet by mercury; while gold, silver, lead, and many
other metals are so. Oil spreads itself in a thin film on the
surface of water, and by its cohesion quiets the agitation of
moderate waves.
17. The cohesion in liquids is much greater than is com-
monly imagined. A disc of glass suspended from the
beam of a balance over a surface of water will adhere with
a measurable force to the water when brought
in contact with it. The force required to with-
| draw it is that which will rupture the cohe-
! sion of the outer row of particles at the edge of
the disc, then the next row, and so on to the
centre a, as shown in the circles on fig. 7. In
Fig. 7. the soap-bubble we see a thin film of water,
Illustrate this by fig. 6. Explain the action of light bodies on water.
What is wettiug? 17. What of cohesion in liquids? Explain the adhe-
sive disc and the soap-bubble.
Digitized by VjOOQ IC
THE ATMOSPHERE.
23
f lying us a beautiful example of the cohesive power of water,
t is a great hollow drop of water. The cohesive power
in the film of the bubble is so great that if the pipe bo
taken from the mouth before the bubble leaves it, a stream
of air will be forcibly driven from the bore by the contrac-
tion of the film, which will deflect the flame of a candle. To
the same cause is ascribed the spherical form of the dew-
drop, the cohesion in the outer row of particles.
18. In the structure of plants and of animals, capillary
attraction performs functions of the highest importance in
the economy of life. Animal membranes possess the power
of exuding or of absorbing fluids from their surfaces. This
power has by several authors been considered as a special
attribute of animal tissues, and as such has received the
name of endosmose and exosmose, or the inward and the out-
ward force of membranes. These actions are generally
regarded as modifications of capillarity, and may be well
illustrated by the endosmometer, (fig. 8.) An
open glass b has it lower end tied over by a bit
of bladder c, and its upper opening elongated
by a narrow glass tube a, this apparatus is
filled with weak sugar-water, and is placed in
an outer vessel n, filled with strong syrup of
sugar. Soon the column of fluid is seen to
mount from a to o or out at the top, from the
penetration of the denser fluid through the
membrane. The power which plants possess of
absorbing the nutritive fluids from the soil
through the delicate bulbous ends of their spog-
nioles is supposed to be identical with that force Fig. 8.
shown in this instrument.
19. In gases, the force of cohesion among the particles
is entirely subordinate to the repulsive action by which they
are expanded. The physical properties of gaseous bodies
are best understood when we study
%
The Mechanical Properties of the Atmosphere.
20. We on the surface of this earth are at the bottom
of a vast aerial ocean, in which we live and move and have
Whence the form of the dew-drop ? 18. What i§ endosmoso ? What
exosmose? Explain the endosmometer. 19. What of cohesion in gases ?
Digitized
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24
MATTER.
our being. From its chemical influence we cannot escape,
nor free ourselves from the vast load of its mechanical pres-
sure which we unconsciously sustain. It penetrates deeply
into the crust of the earth, and is largely dissolved in its
waters. All that relates to its chemical history will be
given in its appropriate place. Its mechanical properties
demand attention now. What is true of the mechanical
properties of air is also true of the gases.
21. Elasticity. — Vessels filled only with air we call
empty ; but it is obvious, when we plunge an empty air-jar
beneath the surface of water, that it contains an elastic and
resisting medium, which must be displaced before the vessel
can be filled with water. Elasticity is the most remarkable
physical property of the atmosphere and of all gases. Upon
this property depends the construction of
22. The air-pump , an instrument in principle like the
common water-pump. It depends for its action on the elas-
ticity of the air. Suppose. two tight-bottomed cylinders, a
and b, ("fig. 9,) to be filled with air. If a solid plug, or pis-
ton, is fitted to each so tightly that no air can pass between
it and the sides of the vessel, we
shall find it impossible to force down
the piston to the bottom of the cylin-
der. It descends a certain distance
q with an increasing resistance, and
is again restored, as with the force of
a spring, so soon as the pressure is
removed. If we suppose one of the
pistons to be in the position shown in
by and the air beneath it of the same
tension or. density as that above, and
we attempt to draw out the plug by
its stem, we also feel a continually
increasing resistance, and the piston
returns forcibly to its former posi-
our hold. We thus demonstrate the
Such
(
> ■
Q
pi
it!1'"
1 Mi
.-"!■
a
J
b
Fig. 9.
tion when we release
elasticity of the air, and also its weight and pressure,
an arrangement of apparatus, slightly modified, is an air-
pump. If each of the pistons is pierced with a hole, over
20. What is said of the aerial ocean? 21. Demonstrate the elasticity of
air by an empty vessel. 21. What is the air-pump ? How does it em
ploy elasticity ? Illustrate this by fig. 9.
Digitized
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THE ATMOSPHERE.
25
which is. a flap, or valve, of leather or silk v, opening upward,
and closing with the slightest downward pressure, and a
similar opening, or valve,
be provided in the bottom
of each cylinder v, we have
an air-pump. (Fig. 10.) ~
It remains only to connect 1
the cylinders by a duct
with the plate on which
the air-receiver R is placed,
and to provide suitable
movements for the pistons
by a lever or otherwise, |
and our instrument is
complete. The plate and L "
receiver are accurately
ground to fit air-tight, and
great pains are taken to
have all parts of the ap- Fis- 10»
paratus as perfectly air-tight as possible.
23. Vacuum. — It is obvious that the air in the receiver will,
by virtue of its elasticity, rush into the cylinders alternately
as these are moved ; the valves in the cylinders preventing
the return of the air to the receiver, while they permit the
escape of the successive portions from within, and those on
the piston closing the access of the outer air. Thus, with
each movement of the lever, fresh portions of air from the
receiver, more and more rare each time, will find their way to
the cylinders and be pumped out, while the space in R be-
comes constantly more void, until the vacuum is completed.
This happens whenever the weight and resistance of the
valves in the cylinders is greater than the elastic force of the
rarefied air in the receiver. And hence it is obviously impos-
sible to make a perfect vacuum by mechanical means. There
will always remain a certain very tenuous atmosphere in
even the most perfect and delicate air-pump, unless, indeed,
it be removed by chemical means. This may be done by em-
ploying a bell-jar filled with carbonic acid, the last portions
of which may be removed by potassa or caustic lime — prc-
How are the valves of the pump arranged? 23. What is a vacuum?
Why is a perfect vacuum impossible ? How max the last portions of air
be removed ?
Digitized
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26
MATTEE.
1
viously placed for that purpose in a vessel on the pump-
plate. The French instruments often have the cylinders of
glass, to expose the mechanical movements
of the valves and pistons. Excellent air-
pumps, with only one cylinder, on the plan
proposed by Leslie, are furnished by the in-
strument-makers in Boston and New York.
24. The bulk and density of the atmosphere
varies with the mechanical pressure to which
it is submitted. This inference is drawn
from what has just been said regarding the
theory of the air-pump. The volume of the
air is inversely as the pressure to which it
is subjected, while its density is directly as
this pressure. This is known as Mariotte's
law, from its discoverer, an Italian philoso-
pher of that name.
Fig. 11 shows the simple apparatus used
for demonstrating this law. It is a glass tube
turned up and sealed at the lower end : a gra-
duated scale of equal parts is attached to it.
Mercury is poured into the open end of this
tube so as to rise just to the first horizontal
line ; a portion of air of the ordinary elas-
ticity is thus enclosed in the short limb of
9 inches. Now if mercury be poured into
the longer leg, so that it may stand at 30
inches above the level of the mercury is
the shorter leg, it will press with its whole
weight on the included air, which will then
be found to occupy 4} inches, or only half
of its former space. If, in like manner, the
column of mercury be increased to twice this
length, its pressure on the included air will
n be tripled, and the space occupied by it will
| be reduced to one-third, and so on in simple
jf proportion. It consequently happens that
' at a pressure of seven hundred and seventy
Fig. n. atmospheres, air would become as dense as
24. What if the relation of volume to density in the air? What is the
law of Mariotte ? Explain figure 11. When is air as dense as water ?
Digitized
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THE ATMOSPHERE.
27
vatcr. The terms tension and density, as applied to gases,
uave the same meaning.
25. The weight of the atmosphere is of course shown bj
<he air-pump. The receiver is fixed by the first stroke of
the pump, and if we employ on the plate a small glass,
>pen at both ends, (fig. 12,) and cover the
upper end with the hand, we shall find it
fixed with a powerful pressure. This is
vulgarly called suction, but is plainly due
>nly to the weight of air resting on the sur-
face of the hand, and rendered sensible
by the partial withdrawal of the air be-
low. Hence, all vessels of glass used on Kfr **•
the air-pump are made strong, and of an arched form, to
resist this pressure. Square vessels of thin glass are imme-
diately crushed on submitting them to the at-
mospheric pressure, or exploded by the removal'
of the surrounding air while they are sealed. The
weight of the air is also well shown by the burst-
ing of a piece of bladder-skin tied tightly over
the mouth of an open jar on the plate of the
air-pump. As the pump is worked, the flat sur-
face of the bladder becomes more
and more concave, and at length
bursts inward with a smart ex-
plosion.
26. Numerous common facts and
experiments illustrate the same
thing. Were the atmospheric pres-
sure removed from under our feet,
we should be unable to move ; and
the difficulty we experience when
walking on clay is due to a partial j
vacuum formed by the close con-
tact of the foot to the plastic soil,
excluding the air. Boys raise .
bricks and stones by a " sucker"
of moist leather, on the same prin-
ciple. The power of the atmo-
spheric pressure to raise heavy weights is well shown in the
Fig. 13.
25. What illustrations of the weight of the air are given in figs. 12 and
13 ? 26. How is the weight raised in fig. 14 ?
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28 MATTER
annexed apparatus, (fig. 14.) A glass jar, having an open
bottom, is covered with impervious caoutchouc. When a
vacuum is produced in the jar, the yielding cover rises,
carrying with it a weight which is below. This is sustained
in the air, as by an elastic spring. The amount of the atmo-
spheric pressure has been experimentally determined as equal
to fifteen pounds on every square inch of surface. This fact
is demonstrated by the
27. Barometer. — This instrument (as its name implies)
enables us to weigh the air. It was discovered by Torricelli,
an Italian philosopher, in the year 1643. When a
glass tube, (fig. 15,) sealed at one end, and about 36
inches long, is filled with mercury, the open end closed
by the finger, and inverted in a vessel containing mer-
cury, so that the open end may be beneath the sur-
face, so soon as the finger is withdrawn the mer-
curial column is seen to fall some distance, and,
after several oscillations, to come to rest at a cer-
tain point, where it is apparently stationary. At
the level of the sea, this point is found to be about
30 inches above the surface of the mercury in the
basin. The empty space above the mercury is the
most perfect vacuum that can be produced; and,
in honor of its discoverer, is called the Torricellian
vacuum.
The mercury is sustained at this height by the
pressure of the atmosphere on the surface of the
fluid in the basin, and the height of the column
varies with the atmospheric pressure, and with toe
elevation of the instrument above the level of the
ocean. Had water been the fluid employed, it would
have required a tube more than 34 feet long to
accommodate the column. If the experiment be
tried above the ocean level, as on the top of a lofty
mountain, the column of mercury will be found of
I a less elevation in proportion to the height of the
[mountain. It was the distinguished Pascal who
* first, in 1647, suggested this experiment on the top
Fig. 15. of a mountain in France, as conclusive proof that
27. What is the barometer ? Describe its principle ? What is the To-
ricellian vacuum? Why is 30 inches the height? What was Pascal's
suggestion ?
Digitized
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THE ATMOSPHERE.
29
it was the weight of the air which sustained the mercury in
the barometer.
28. The principle of the barometer is beautifully shown in
16. A large bell-glass, with a wide mouth c, has two sy-
phon barometer tubes attached. One a has the mercury stand-
ing at the proper height at a, while its cistern enters the bell.
The other tube at one end also enters the bell, but, bending
upon itself, it holds a portion of mercury in the outer cis-
tern b on its other extremity. When this apparatus is
placed on the air-pump and exhausted of air, the
mercury a falls in proportion to the vacuum pro-
duced, while that in b mounts in like proportion.
In a we see the effect of diminished pressure, as
on a mountain or in a balloon ; in b the pressure
of the external air causes the mercury in it to
mount, forming a gauge of the exhaustion.
29. If the tube of the barometer has an area
of one inch, and the height of the column is 30
inches, the weight of the mercury sustained in it
is by experiment found to be fifteen pounds. And
this is the pressure which the atmosphere ex-
ercises on every square inch of the earth's sur-
face. A column of atmospheric air one inch
square, and reaching to the uppermost limits of
the aerial ocean, will also weigh, of course, just
fifteen pounds. We thus come to regard the
mercury in the barometer as the equipoise on one
arm of a balance, of which the counterpart is
the atmospheric column. As the latter varies {
daily from meteoric causes, so also does the
height of the mercurial column oscillate in just
proportion. Hence the barometer is properly called a
"weather-glass," and by its movements we judge of the
approach of storms. These changes of level sometimes
amount at the same place to 2 or 2 J inches, although
usually they are much less.
Various forms of the barometer are in use : those for
measuring the elevation of mountains are so constructed
I
Fig. 16.
28. How is the principle of the barometer explained in fig. 16? Why
does the mercury in a fall? Why does that in o rise? 29. What is
the pressure of air on a square inch of surfaoe ? How is this shown by
the barometer ? How is tho barometer a weather-glass ?
Digitized
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80
MATTER.
as to be easily transported. A good
form of the mountain barometer is
shown in fig. 17, supported on a tri-
pod, which, with the instrument, can
be safely packed in a leather case.
80. The Aneroid Barometer is de-
signed to supersede the mercurial in-
strument in those situations where the
oscillating motion of the mercury de-
stroys the value of its indications, as in
travelling, in aeronautical excursions, at
sea, and on many other occasions when
the common barometer is inconve-
nient. It depends on the variation
in form of a thin vase D J) (fig. 18)
of copper, which being partially ex-
hausted of air changes its dimensions
with every variation in atmospheric
^pressure. These motions are multi-
plied and transferred by the combina-
tion of levers C, K, 1, 2, and 3, &o.,
in such a manner that the index
reads the barometric conditions of
the atmosphere on a dial. The in-
dex is set by adjusting screws, to
correspond with a standard mer-
curial instrument, and the accuracy
of each aneroid is tested by the air-
pump.
81. Weight of the Atmosphere. — One hundred cubic inches
of atmospheric air at 80 inches of the barometer and 60° Fahr.
weigh 30 T^/^ grains, while the same bulk of water would
weigh about 25,250 grains. Air of the above condition is as-
sumed as the standard unity for the density of all other aeri-
form bodies. A man of ordinary size has a surface of about
15 square feet, and he must consequently sustain a pressure
on his body of over 15 tons. This prodigious load he bears
about with him unconsciously, because the mobility of the
particles of air causes it to bear with equal force on every
Fig. 17.
Fig. 18.
30. What is the aneroid barometer? 81. What is the weight of air?
What weight of air does a man sustain?
Digitized
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WEIGHT AND SPECIFIC GRAVITY. 81
part of his body, beneath his feet as well as on his head,
and in the inner cavities as well as on the outer surface.
32. Limit* of the AtmospJiere. — A person who has risen
in a balloon, or on a mountain, to the height of 2*705 miles,
or 14,282 feet, has passed through one-half of the entire
weight of the air, and finds his barometer to indicate this bj
standing at 15 inches.
The air grows more and more rare as we ascend, and the
barometer falls in exact proportion. The inconvenience
which travellers have experienced in ascending high moun-
tains has, it is said on good authority, been very much ex-
aggerated. The heart continues its action under a diminished
external pressure, and no serious consequences, it is believed,
ever follow, as the bursting of bloodvessels or lesion of the
lungs, as some have asserted. On the summit of Chimbo-
razo, Baron von Humboldt found that his barometer had
sunk to 13 inches 11 lines ; and the same philosopher de-
scended into the sea in a diving-bell until the mercurial co-
lumn rose to 45 inches : he consequently has safely expe-
rienced a change of 31 inches of pressure in his own person.
The upper limits of the atmosphere cannot be determined
very accurately • but, from the refraction of light as observed
in the rising and setting of stars, astronomers have inferred
that it is probably about forty-five miles high.
Weight and Specific Gravity,
33. Weight is the measure of the force of gravity, and
is directly proportional to the quantity of matter in a given
space. Weight is determined by the balance, an instru-
ment to which the chemist appeals at every step of his in-
vestigations. Modern instruments enable us to determine
this element of accurate science, to the greatest nicety.
The specific gravity of a body is its weight as compared
with an equal bulk of some other substance assumed as the
unit of comparison. A cubic inch of gold is more than 19
times as heavy as a cubio inch of ice or of water : hence the
gold is said to have a specific gravity of 19, compared with
water.
Pure water has been adopted as the standard of compari-
32. What is the height of the atmosphere? 33. What is weight?
What is speeifio gravity I What is the standard of speciflo gravitj ?
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S2
MATTER.
sou for the specific gravity of all solid and liquid substances,
taken at 60° Fahrenheit. For gases and vapours, common
air, dry and at the temperature of 60° and 30 inches of ba-
rometric pressure, is the standard assumed. Regard is had
to the conditions of temperature and pressure because the
bulk of all bodies varies sensibly with these conditions.
84. The specific gravity of solids is determined by the
theorem of the renowned Archimedes, that " when a body
is immersed in water, it loses a portion of its weight exactly
equal to the weight of the water displaced." He thus de-
tected the fraud of the goldsmith who fur-
nished to King Hiero of Syracuse, as a crown
of pure gold, one fashioned of base metal — the
specific gravity of the debased alloy was too
small for gold. It is plain that a solid dis-
places, when immersed, exactly its own bulk
of water, and loses weight to a corresponding
amount. Hence, if we weigh a body first
in air and then in water, the loss of weight ob-
served, is equal to the volume of water, cor-
responding to the bulk of the solid. Fig. 19
shows a group of crystals of quartz suspended
from the underside of the scale-pan by a fila-
ment of silk. Its weight in air was previously
determined. Its diminished weight in the
water, subtracted from the weight in air, gives
Fig. 19. a sum eqUai to the bulk of water displaced.
From these elements is deduced the rule to find the specific
gravity of a solid. " Subtract the weight in water from
the weight in
air, divide the
weight in air
by this dif-
ference, and
the quotient
will be the
specific gra-
vity." Fig.
20 shows the
Fig. 20. balance ar-
How is it determined ? What is the theorem of Archimedes ? 34. How
is this illustrated in fig. 19 ? Give the rule for specific gravity
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WEIGHT AND SPECIFIC GRAVITY.
33
ranged for taking the specific gravity of the solid a sus-
pended in water from the hook b. A single example will
serve to illustrate this rule. We find, on trial, that the
Weight of a substance in air, is. 357*95 gra.
Weight of the substance in water 239-41 "
Difference 118*4 «
847-95 0 A<l ,a
jj^ - 3-01 specific gravity.
35. The specific gravity of sub-
stances lighter than water may be
determined by attaching them to a
mass of lead or brass, of known
weight and density. Subtances in
small fragments or in powder are
placed in a small bottle, fig. 21,
holding, for example, a thousand
grains of water. Those soluble in
water are weighed in a fluid in which
they are insoluble and whose den-
sity is separately determined. In
these cases a simple calculation re-
fers the results to the known den-
sity of pure water.
36. The specific gravity of liquids may
be ascertained in a small bottle holding
a known weight of pure water. These
bottles usually have a small perforation in
the stopper, as seen in the figure 22, through
which the excess of fluid gushes out, and
may be removed by careful wiping. The
weight of the bottle, dry and empty, is
counterpoised by a weight kept for that
purpose. Fig. 22.
37. The Hydrometer is an instrument of great use in de-
termining the specific gravity of liquids without a balance.
It is simply a glass tube, fig. 23, with a bulb blown on one
end of it, containing a few shot, to counterbalance the instru-
ment ; and a paper scale of equal parts is sealed within the
Pig. 2L
Give an example. 35. How is specific gravity determined on bodies
lighter than water? on powders? on soluble substanoes? 36. On fluids?
27. What is the hydrometer ? Describe its use.
i
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84
MATTEB.
Fig. 24.
stem. This scale indicates the points to which the stem sinks
when immersed in fluids of different de&-
sities. The fluid, for convenience, is
placed in a tube or narrow jar, (fig. 24):
the more dense the liquid is, the less
quantity will the hydrometer displace,
while in a lighter fluid it will sink deeper.
The zero point of the scale is always
placed where the instrument will rest in
pure water, after which the graduation
is effected on a variety of arbitrary scales,
all of which can, however, be referred to
the true specific gravity by calculation,
or by reference to a table such as may be
• found at the close of this volume. Hy-
drometers are also prepared with the true
specific gravities marked upon them, read-
ing even to the third decimal place accurately. The scales
of these instruments read either up or down, according as the
fluid to be measured is either heavier or lighter than water.
In case of alcohol, the graduation of the hydrometer is made
to indicate the number of parts of pure alcohol in a hundred
parte of a liquids—absolute alcohol being 100, and water 0.
The hydrometers of Baume* (French scale) are much used
in the arts. These instruments are of the greatest service
to the manufacturer, and, when carefully made, are suffi-
ciently accurate for most purposes of the laboratory. They
should always be proved by comparison with the balance
and thermometer before they are accepted as standards.
For many purposes they are made of brass or ivory, as well
as of glass.
Little balloons or bulbs of glass, are frequently
employed to find, in a rough way, the density of
fluids. When several of them are thrown in a
fluid of known density, some will sink, some rise
even with the surface, and others will just float.
Those which just float are taken, and being
Fig. 25. marked (as in fig. 25) with the density of the
Jiquid which they represent, are then used to determine the
specific gravity of liquids of unknown density. They are
called specific gravity bulbs, and are of great service in as-
What scales ore used in Hydroinoters ? What use is made of little
bulbs of glass »
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SPECIFIC GRAVITF OF OASES.
35
certaining the density of gases reduced to a liquid by pres-
sure in glass tubes, when, from the circumstances of the
experiment, all the usual modes of ascertaining specific gra-
vity are inapplicable.
38. The water balloon, or " Cartesian devil," is an ele-
gant illustration of the law of specific gravity. In this toy
the balloon, or figure, contains a portion of water
just sufficient to enable it to float. It is placed
in a tall jar of water, over the top of which is tied
a cover of India-rubber. Pressure upon this cover
forces an additional quantity of water into the
balloon by an opening (v1 fig. 26). The density
of the mass is thus increased, and it sinks until
the pressure is removed, when, the air in the bal-
loon expanding, forces out the superfluous water,
and the glass rises again. Such is the mode pro-
vided by nature in the structure of the nautilus
and ammonite, by which means those curious ani- Fig. 26.
mals are able, at will, to rise or sink in the ocean.
39. Specific Gravity of Gases. — It remains only, under
this head, to speak of the modes used for determining the
specific gravity of gases and vapors. For this purpose a
globe, (fig. 28,) or other conveniently formed glass
vessel, holding a known quantity by measure,
(usually 100 cubic inches,) is care-
fully freed from air and mois-
ture, by the air-pump or exhausting
syringe. It is then filled with
the gas or vapor in question, at
60° Fahrenheit, and 30 inches of
the barometer, (33,) and weighed.
The weight of the apparatus filled
with common air being previously
known, the difference enables the
experimenter to make a direct com-
parison. Figure 27 shows an appa-
ratus for this purpose ; the globe b
Fig. 27. js provided with a stopcock e, and fitted by a
screw to the air- jar a. The jar is graduated so that the
quantity of air or other gas entering may be known from
38. What is the water balloon. What animal has the same principle ?
Uow is air weighed ? 39, Describe figures 27 and 28. How do we find
lbs speeifie gravity of gases ?
Fig. 28.
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86 CRYSTALLIZATION.
the rise of the water in a. It is thus found that 100 cu-
bic inches of pure dry air weigh 30-829 grains, while the
same quantity of hydrogen gas weighs only 2*14 grains,
being about fourteen times lighter than air. To dry the air
or gas it must be made to pass through a chlorid of calcium
tube, or other drying apparatus, before entering the balloon.
CRYSTALLIZATION.
Nature of Crystallization and Forms of Crystals.
40. Nature of Crystallization. — The forms of living na-
ture, both animal and vegetable, are determined by the laws
of vitality, and are generally bounded by curved lines and
surfaces. Inorganic or lifeless matter is fashioned by a dif-
ferent law. Geometrical forms, bounded by straight lines
and plane surfaces, take the place in the mineral kingdom
which the more complex results of the vital force occupy
in the animal and vegetable world. The power which de-
termines the forms of inorganic matter is called crystalliza-
tion. A crystal is any inorganic solid, bounded by plane
surfaces symmetrically arranged and possessing a homoge-
neous structure. •
Crystallization is, then, to the inorganic world, what the
power of vitality is to the organic ; and viewed in this, its
proper light, the science of crystallography rises from being
only a branch of solid geometry to occupy an exalted philo-
sophical position.
The cohesive force in solids is only an exertion of crystal-
line forces, and in this sense no difference can be established
between solidification and crystallization. The forms of
matter resulting from solidification may not always be re-
gular, but the power which binds together the molecules is
that of crystallization.
41. Circumstances influencing Crystallization. — Solution
is one of the most important conditions necessary to crystal-
lization. Most salts and other bodies are more soluble in
hot than in cold water. A saturated hot solution will
usually deposit crystals on cooling. Common alum and
Glauber's salts are examples of this. Solution by heat, or
How much do we thus find the air to weigh ? 40. What is crystalliza-
tion said to be ? What is the cohesive force ? 41. Name some circum-
stances which influence crystallization.
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POLARITY OP MOLECULES.
37
fusion, also allows of crystallization, as is seen in the crystal-
line fracture of zinc and antimony. Sulphur crystallizes
beautifully on cooling from fusion, and so do bismuth and
some other substances. The slags of iron-furnaces and sco-
riae of volcanic districts present numerous examples of mine-
rals finely crystallized by fire. Numerous minerals havo
been formed by heating together the constituents of which
they are composed. Blows and long-continued vibration
produce a change of molecular arrangement in masses of
solid iron and other bodies, resulting often in the formation
of broad crystalline plates. Rail-road axles are thus fre-
quently rendered unsafe. In short, any change which can
disturb the equilibrium of the particles, and permits any
freedom of motion among them, favours the reaction of the
polar or axial forces, (42,) and promotes crystallization.
42. Polarity of Molecules. — The laws of crystallization
show that the molecules have polarity. That is, these mole-
cules have three imaginary axes passing through them, whose
terminations, or poles, are the centre of the forces by which
a series of similar particles are attracted to each other to
form a regular solid. These molecules are either spheres
(fig. 29) or ellipsoids, (fig. 31,) and the three axes (N S)
Fig. 29. Fig. 30. Fig. 31.
are, always, either the fundamental axes, or the diameters of
these particles. In the sphere (fig. 29) these axes are always
of equal length, and at right angles to each other, and the
forms which can result from the aggregation of such spheri-
cal particles can be only symmetrical solids, such as the
cube and its allied forms. The cube drawn about the sphere
(fig. 29) may be supposed to be made up of a great number
of little spheres (fig. 30) whose similar poles unite N and
S. In the ellipsoid (fig. 31) all the axes may vary in length,
42. What do the laws of crystallization show? What are the aorta of
molecules? What forms have the molecules of bodies? What forms c*d
come from the spherical particles ? How may the structure of the cube
be shown? How are the axes of the ellipsoid ?
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88
0RY8TALLIZATIO1C.
giving origin to a vast diversity of forms. Under the in-
fluence of heat, the crystallogenic attraction loses its polarity
and force, and the body becomes liquid or gaseous, and sub-
ject to repulsive force. The return to a solid state can ocour
again only when the attractions become polar or axial.
43. Crystalline Forms. — The mineral kingdom presents as
with the most splendid examples of crystals. In the labora-
tory we can imitate the productions of nature, and in many
cases produce beautiful forms from the crystallization of
various salts, which have never been observed in nature.
The learner who is ignorant of the simple laws of crystal-
lography, sees in a cabinet of crystals an unending variety
and complexity of forms, which at first would seem to baffle
all attempts at system or simplicity. Numerous as the natu-
ral forms of crystals are, however, they may be all reduced
to six classes, comprising only thirteen or fourteen forms.
From these all other crystalline solids, however varied, may
be formed by certain simple laws.
44. The first class of crystalline forms includes the cube,
(fig. 32,) the octahedron, (fig. 33,) and the dodecahedron,
(fig. 34.) The
faces of the cube
are equal squares.
The eight solid
angles are similar,
and also the twelve
Fig. 32. Fig. 33. Fig. 34. edges. The three
axes are equal, (aa, bb, cc^) and connect the centres of op-
posite faces. The regular octahedron (fig. 33) consists of
two equal four-sided pyramids, placed base to base. The six
solid angles are equal, and so also the edges, which, as in
the cube, are twelve in number. The plane angles are 60°,
and the interfacial 109° 28' 16". The axes connect the
opposite angles ; they are equal and intersect at right angles.
This class is also called the monometric, (menos, one, and
metron, measure,) the axes being equal.
45. The second class includes the square prism (fig. 35)
and square octahedron (fig. 36.) In the square prism (fig.
35) the eight solid angles are right angles, and similar, as in
the cube. The eight basal edges are similar, but differ from
BE
43. How are the complex forms of crystals arranged and simplified?
44. Describe the first class of fundamental forms.
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FOKMS Of CBYSTALS.
8»
/
71. —
X
fc_
0
ft
^
OS
/
^
»
y
' r
Fig. 37.
Fig. 38.
Fig. 39.
the four lateral. The two basal
faces are squares, the four lateral
are parallelograms. The axes con-
nect the centres of opposite faces,
and intersect at right angles.
Square prisms vary in the length
of the vertical axis, (a, a,) which is
hence called the varying axis; the Fig* 35' Fig* 36'
lateral axes (bb, cc) are equal. This class is also called the
dimetric, (dis, twofold, and metron, measure.)
46. The third class contains the rhombic prism, (fig. 37,)
the rectangular prism, (fig. 38.) and the rhombic octahedron,
(fig. 39.) The rhom-
bic prism (fig. 37) has
two sorts of edges, two
acute and two obtuse.
The solid angles are,
therefore, of two kinds,
four obtuse and four
acute. The axes are
unequal and cross at right angles. The lateral connect the
centres of opposite edges, bb9 cc. The basal faces are rhom-
bic. The rectangular prism (fig. 38) has all its solid angles
similar. There are three kinds or sets of edges, four lateral,
four longer basal, and four shorter basal. The axes connect
the centres of opposite faces, and intersect at right angles.
The three are unequal. The rhombic octahedron (fig. 39)
has three unequal axes, connecting opposite solid angles.
All the sections in this solid are rhombic. This class is
also called the trimetric, from tru} threefold, and metron,
measure.
47. The fourth class contains the oblique rhombic prism,
(fig. 40,) and the right rhomboidal prism, (fig. 41.) The
oblique rhombic prism is represented
in the figure as inclining away from
the observer, the prism being in posi- <
tion when standing on its rhombic
base. The upper and lower solid
angles in front are dissimilar, one
obtuse and the other acute. The four lg* *
Fig. 41.
45. What are the forms of the second class ? Describe them. 46. What
forms make up the third class ? Describe them. 47. What forms does
the fourth class contain ? How do they differ ?
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40
OEY8TALLIZATIOW.
lateral solid angles are- similar. Two of the lateral edge*
are acute, and two obtuse; and the same is true of the basal.
The lateral axes are unequal; they connect the centres of
opposite lateral edges, and intersect at right angles. The
vertical axis is oblique to one lateral axis, and perpendicular
to the other. The right rhomboidal prism (fig. 41) has two
obtuse and two acute lateral edges, and four longer and four
shorter basal edges. The solid angles are of two kinds,
four obtuse and four acute. The axes connect the centres
of opposite faces; one is oblique, the others cross at right
angles. This is also called the monoclinate, (monos, one,
and clino, to incline,) having one inclined axis.
48. The fifth class includes the oblique rhomboidal prism.
^I>. In this solid only those parts diagonally opposite
d^ «[^| are similar, and consequently it has six kinds of
k^ *" v* edges. The axes connect the centres of opposite
^*£^h faces. They are unequal, and all their inter-
<Tf T/? sections are oblique. This is called the triclinate
Z^\ class, from tris, three, and clino, to incline, the
Fig. 42. three axea an Deing obliquely inclined.
49. The sixth class includes the hexagonal prism ("fig. 43)
and the rhombonedron,
(figs. 44 and 45.)
hexagonal prism
> twelve similar ang^,
and the same number of
similar basal edges. The
lateral edges are six in
Kg. 43. Kg. 44. **«• number, and similar.
The lateral axes are equal, and cross at 60°, connecting the
centres of opposite lateral faces or lateral edges.
The rhombohedron is a solid whose six faces are all
rhombs. The two diagonally opposite solid angles (a a)
consist of three equal obtuse or equal acute plane angles,
and the diagonal connecting these solid angles is called the
vertical axis, (a a.) When the plane angles forming the
vertical solid angles are obtuse, the rhombohedron is called
an obtuse, (fig. 44,) and if acute, it is called an acute rhom-
bohedron, (fig. 45.) The three lateral axes are equal, and
What other names have the first, second, and third classes ? 48. What
solid is included in the fifth class ? 49. Name the two solids in the sixth
class of fundamental forms. How are the hexagonal prism and rhombo-
hedron related? How are rhombohedrons distinguished?
The
has
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MEASUREMENT OF CRYSTALS.
41
intersect at angles of 60° : they connect the centres of op-
posite lateral edges. This will be seen on placing a rhom-
bohedron in position and looking down upon it from above.
The six lateral edges will be found to be arranged around
the vertical axis, like the sides of an hexagonal prism.
50. The mutual relations of the forms of crystals are well
shown in the foregoing arrangement. Thus, in each of the
six classes, the first named solid alone is, properly considered,
a fundamental form, the others in each class being frequently
found as secondaries to these. The six fundamental forms
are the cube, square prism, right rectangular prism, oblique
rhombic prism or right rhomboidal prism, oblique rhomboi-
dal prism, and the hexagonal prism or rhombohedron.
51. The structure of crystals is often seen by lines on
their surfaces, or by the ease with which the crystal splits
in certain directions. Common mica cleaves in leaves;
galena breaks only in cubes, fluor-spar in octahedra, calc-spar
only in rhombohedrons. This property is called cleavage.
It does not exist in all crystals, and is not of equal facility
in all directions. Thus, in mica, cleavage is easy in one
direction only; while in fluor-spar and calcite it is equally
easy in three directions respectively.
Measurement of Crystals.
52. Common Goniometer.* — The angles of crystals are
measured by means of instruments called goniometers. £he
common goniome-
ter, which is here
figured, consists of
a light semicircle
of brass, (fig. 47,)
accurately graduat-
ed into degrees, and
having a pair of
steel arms (fig. 46)
moving on a central
pivot, and so ar-
ranged as to slip in
Fig. 47.
50. What is said of the relations of fundamental forms ? What six fun-
damental forms are named ? 51. What is cleavage in minerals ? On what
does it depend ? Give examples. Is it equal in all minerals?
* From the Greek, gonia, an angle, and metron, measure.
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42
CRYSTALLIZATION.
Fig. 48.
a groove over each other. The points a a can thus be made
to embrace the faces of a crystal whose angle we wish to
measure. The graduated semicircle is applied with its centre
at the point of intersection, when the angle is read on tho
arc. Where the greatest nicety is required, a much more
delicate instrument is used.
b6. WoUaston's Reflective Goniometer. — The principle of
this instrument may be understood by reference to fig. 48,
which represents a crystal (o)
whose angle (a b c) is required.
The eye at P, looking at the face
(b c) of the crystal, observes a
reflected image of M in the direc-
tion of P N. The crystal may
now be so turned that the same
image is seen reflected in the next
face, (6 a,) and in the same direc-
tion, (P N.) To effect this, the crystal must be turned
until a b has the present position of b c. The angle d b c
measures, therefore, the number of degrees through which
the crystal must be turned. But d b c subtracted from
180° equals the required angle of the crystal ab c; con-
sequently, the crystal passes through a number of degrees,
which, subtracted from 180°, gives the required angle.
When the crystal is attach-
ed to a graduated circle, we
have the goniometer of Wol-
laston, which is represented
in fig. 49. The crystal to
be measured is attached at/,
and may be adjusted by the
milled head c and arm d,
moving independent of the
great circle a. When adjust-
ed in the manner described
above, the wheel is revolved
until the image of M is seen
Fig. 49. in the second face. This
movement is practically a subtraction of the angle a b c
52. What is a goniometer? Explain the common one and its use. 63.
Explain the principles of Wollaston's goniometer from figure 48. How
U this principle used in Wollaston's instrument ?
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60URCE8 AND NATURE 07 LIGHT. 48
from 180°, and the result is read directly by the vernier e.
— The subject of crystallography cannot be further illustrated
here; but the learner who desires to pursue it, is referred to
the highly philosophical treatise on mineralogy by Professor
J. D. Dana.
n. LIGHT.
54. The physical phenomena of light properly belong to
t!he science of Optics, a branch of natural philosophy not
necessarily connected with chemistry. A knowledge of some
of the laws of light is, however, required of the chemical
student.
55. Sources and Nature of Light. — The sun is the great
source of light, although we know many minor and artificial
sources. Of the real nature of light we know nothing. Sir
Isaac Newton argued that it was a material emanation from
the sun and other luminous bodies, consisting of particles so
attenuated as to be wholly imponderable to our means of
estimating weight, and having the greatest imaginable repul-
sion to each other. These particles, by his theory, are supposed
to be sent forth in straight lines, in all directions, from every
luminous body, and, falling on the delicate nerves of the
eye, to produce the sense of vision. This is called the New-
tonian or corpuscular theory of light. It is not generally
adopted by physicists, but the language of optical science is
formed mainly in accordance with it. The other view or
theory of light, which is now almost universally accepted,
is called the wave or undulatory theory. It is known that
sound is conveyed through the air by a series of vibrations
or waves, pulsating regularly in all directions, from the
original source of the sound. In the same manner it is
believed that light is conveyed to the eye by a series of un-
ending and inconceivably rapid pulsations or undulations, im-
parted from the source of light to a very rare or attenuated
medium, which is supposed to fill all space. This medium
is called the luminiferous ether.
Astronomy furnishes evidence of the presence in space
of a medium resisting the motion of the heavenly bodies
54. What is optics ? 55. Name sources of light. What is the New-
tonian hypothesis ? What is the other theory ? What is the medium of
light? What evidence does astronomy give of an ether?
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44 LIGHT.
Encke's comet is found to lose about two days in each sue
cessive period of 1200 days. Biela's comet, with twice that
length of period, loses about one day. That is, the succes-
sive returns of these bodies is found to be accelerated by this
amount. No other cause for this irregularity has been
found but the agency of the supposed ether.
56. Undulations. — The propagation of force by undula-
tions, pulsations, or waves, is a general fact in physics. A
vibrating cord communicates its waves of motion to the sur-
rounding air, and a musical tone results.
If a long cord A B, fig. 50,
be jerked by the hand, the
motion is propagated from
the hand A, in the curve
Fig. 50. V A-®> an<* so on successively
to B, when the motion is
again reflected in the oppo-
1 site phase to the hand, as in
Fi 61^ fig. 51, where the continued
line shows the primary vi-
brations, and the dotted one that which is reflected.
A pebble dropped on the surface of a
quiet pool, produces a series of circular waves
receding to the shore, (fig. 52.) The waves
produced do not transport any light bodies
a accidentally floating on the surface of the
water. These only rise and fall as each
Fig. 52. wave passeg#
57. The measure of the waves on the surface of water ia
from crest to crest, or from hollow to hollow, and* in every
complete wave or entire vibration (fig. 53)
/^T\ the following parts are recognised : aebdc
/ V f / *s *^e whole length of the wave ; aebi the
^4^ phase of elevation, and bde the phase of dc-
pression. The height of the wave is ef, and
g' * its depth g d. The points in which the phasea
of elevation and of depression intersect, as in
fig. 51, are called nodal points, and are always at rest : so
56. How is force propagated ? Illustrate by figs. 50 and 51. Describe
the progress of waves from fig. 52. 57. Name the parts of a wave in fig.
64. Distinguish the phases of elevation and of depression. "What are
D9dal points?
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B
UNDULATIONS 0* UOHT. 41
that light bodies resting on them would remain undisturbed,
which placed elsewhere would be immediately thrown off.
If two waves of equal altitude and arriving from opposite
directions unite, so that the elevations and depressions of
the two correspond, then the resulting wave is doubled.
But if the two meet at half the distance of their respective
elevations and depressions/so that the crest of one corre-
spond to the hollow of the other, then both are obliterated,
and the surface becomes quiet ; or if one wave was larger
than the other, a third wave, corresponding to the difference
only of the other two, results.
58. This is equally true whether we speak of waves of
sound, of heat, of light, or in fluids. That two waves of
sound may meet so as to produce silence, may easily be
shown by vibrating a tuning-fork over an open
glass A, and holding another similar glass B lip jj
to lip with the first, and at right angles with it, (
as shown in fig. 54. The vibrations may be
inoreased by sticking a piece of circular card-
board on one leg of the fork, and by pouring
water into the first glass until the tone is ad- Fig. 54.
justed to a maximum. Or a second fork may
be used in place of B, differing half a tone from the other
fork, (fig. 55.) In this case a series of swells and cadences
will be heard in place of entire silence. In these
cases, the waves of sound interfere, as before, in
the case of the water. In like manner, two cur-
rents of thermo-electricity may meet in such a
manner as to freeze a drop of water in one end of
the arrangement, the current being excited by
heating the opposite end of the system.
59. So two rays of light, AB, CD, fig. 56, Pig w
meeting at the proper interval, (a,) will produce a
beam of double intensity ; but if x ^ ^^ ^^ ^-^1, ^
they meet at the half interval of ^X^'CI^'C^* "*
vibration, darkness results. This m 66
is interference of light. In mo-
ther of pearl and many other natural bodies, a beautiful
play of colors is seen. The microscope reveals on such sur-
When are waves made double, and when set at rest? 58. Illustrate the
interference of waves of sound in figs. 54 and 55. What of thermo-
electricity ? 59. Deicribe the interference df light from fig. 56.
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46 LIGHT.
feces delicate grooves and ridges, and these are at such dm*
tances as to produce interference in the light-waves, result*
ing in partial obscuration and partial decomposition. The
same effect is artificially produced in medal-ruling. This
irised effect can be transferred by pressure or copied by the
electrotype, or even on wax.
60. The transverse vibrations of a ray of light distinguish
this from all other modes of undulation or vibration. Dr.
Bird illustrates this by fig. 57, which represents
a spherical particle of ether alternately extended
and depressed at its poles and equator, oscilla-
ting, or trembling, rather than undulating.
Thus, each particle in turn communicates the
Fig. 67. impulse which it receives, and yet the centre
of each may remain unmoved from its place ;
as motion in a series of ivory balls causes only the termi-
nal one to swing, the intermediate ones remaining unmoved.
In light-waves, the vibration or pendulation of each particle
is perpendicular to the path of the ray ; and yet the alternate
effect of the movements of contiguous particles will produce
a progressive vibration. Thus, in fig.
!©fc- 58, A B C D may represent particles of
^b ether in the path of a ray of light, the
Fig. 58. phases of elevation in A and C and
those of depression in B and D being
coincident The fact of the vibrations of light-ether being
transverse to the path of the ray was first observed by Fres-
nel. These vibrations are conceived to occur in any or every
transverse plane. Leaving these interesting generalizations!
we must briefly recapitulate the well-established
61. Properties of Light — 1st. Light is sent forth in rays
in all directions from all luminous bodies. 2d. Bodies not
themselves luminous become visible by the light falling on
them from other luminous bodies. 3d. The light which pro-
ceeds from all bodies has the color of the body from which
it comes, although the sun sends forth only white light. 4th.
Light consists of separate parts independent of each other.
5th. Rays of light proceed in straight lines. 6th. Light
moves with a wonderful velocity, which has been computed
What instances are named from nature ? 60. What are transverse vi-
brations in light ? How is the undulation thus produced ? What i? said
*f progressive motion ? 61. Enumerate six properties of light.
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REFLECTION. 47
by astronomical observations to be at least one hundred and
ninety-five thousands of miles in a second of time. This
velocity is so wonderful as to surpass our comprehension,
Herschel says of it, that a wink of the eye, or a single motion
of the leg of a swift runner, or flap of the wing of the swiftest
bird, occupies more time than the passage of a ray of light
around the globe. A cannon-ball at its utmost speed would
require at least seventeen years to reach the sun, while light
comes over the same distance in about eight minutes.
62. When a ray of light falls on the surface of any body,
several things may happen. 1st. It may be absorbed and
disappear altogether, as is the case when it falls on a black
and dull surface. 2d. It may be nearly all reflected, as from
some polished surfaces. 3d. It may pass through or be trans-
mitted ; and, 4th. It may be partly absorbed, partly reflected,
and partly transmitted. All bodies are either luminous,
transparent, or opake. Bodies are said to be opake when
they intercept all light, and transparent when they permit
it to pass through them. But no body is either perfectly
opake or entirely transparent, and we see these properties in
every possible degree of difference. Metals, which are among
the most opake bodies, become partly transparent when made
very thin, as may be seen in gold-leaf on glass, which trans-
mits a greenish-purple light, and in quicksilver, which gives
by transmitted light a blue color slightly tinged with purple.
On the other hand, glass and all other transparent bodies*
arrest the progress of more or less light.
63. Reflection. — Light is reflected according to a very
simple law. In fig. 59, if the ray of light fall from F to
P, it is thrown directly, back to
F; for this reason, a person
looking into a common mirror
sees himself correctly, but his
image appears to be as far behind
the mirror as he is in front of it
The line P F is called the normal.
If the ray fall from R to P, it will §§
be reflected to R/, and if from r, lg' *
then it will go in the line /, and so for any other point.
Illustrate its velocity. 62. What happens to incident light ? How are
bodies divided in respect to light? Give illustrations of imperfect
opacity, 63. What is the law of reflection ? What is the normal f
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48
LIGHT.
[f we measure the angles BPF and FPR', we shall find
them equal to each other, and so also the angles rPF and
FP/. These angles are called respectively the angles of
incidence and reflection. We therefore state that the angle
of incidence is equal to the angle of reflection, which is the
law of simple reflection. This law is as true of curved sur-
faces as it is of planes ; for a curved surface (as a concave
metallic mirror) is considered as made up of an infinite
number of small planes.
64. Simple Refraction, — If a ray of light falls perpendi-
cularly on any transparent or uncrystallized surface, as glass
or water, it is partly reflected, partly scattered in all direc-
tions, (which part renders the
object visible,) and partly trans-
mitted in the same direction from
which it comes. If, however, the
light come in any other than a
perpendicular or vertical direction,
as from B to A, on the surface of
a thick slip of glass, as in fig. 60,
it will not pass the glass in the
line BAB, but will be bent or
refracted at A, to C. As it leaves
the glass at 0, it again travels in
a direction parallel to B A, its first course. Refraction, then,
is the change of direction which a ray of light suffers on
passing from a rarer to a denser medium, and the reverse.
In passing from a rarer to a denser medium, (as from air to
glass or water,) the ray is bent or refracted toward a line
perpendicular to that point of the surface on which the light
falls; and from a denser to a rarer medium the law is
reversed.
A common experiment, in illustration of this law, is to
place a coin in the bottom of a bowl, so situated that the
observer cannot see the coin until water is poured into the
vessel ; the coin then becomes visible, because the ray of
light passing out of the water from the coin is bent toward
Fig. 60.
What is the angle of incidence ? What of reflection ? What is true
of curved surfaces ? 64. What is refraction ? Demonstrate the law by
fig. 60. Which way is the ray bent ? Give a familiar illustration of
refraction.
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THE PRISM. 49
the eye. In the same manner, a straight stick thrust into
water appears bent at an angle where it enters the water.
65. Index of Refraction. — The obliquity of the ray tq tho
refracting medium determines the amount of refraction. The
more obliquely the ray falls on the surface, the greater tho
amount of refraction. A little modification of the last figure
will make this clear. Let R A
(fig. 61) be a beam of light falling
on a refracting medium : it is bent
as before to B/. If we draw a circle
about A as a centre, and let fall
the line a a, from the point a, '
where the circle cuts the ray E,
and at right angles to the normal
Ar A, the line a a is called the sine
of the angle of incidence ; while
the line a' a' is catted die sine of
the angle of refraction.
If a more oblique ray r cuts th* circle at b, the line b b
will be longer than the line a a, inasmuch as the angle b A
a is greater than the angle a A a.
The line measuring the obliquity before refraction, when
the ray passes into a denser medium, is always greater than
that which measures it after. The ratio of these lines ex-
presses the refractive power of the medium. This is called
the index of refraction.
In rain water the ratio of these lines is as 529 : 396 or
1*31 ; in crown glass it is as 31 : 20 or 1*55; in flint glass
1-616, and in the diamond 2-43.
66. Substances of an inflammable nature, or rich in carbon,
and those which are dense, have, as a general thing, a higher
refracting power than others. Sir Isaac Newton observed
that the diamond and water had both high refracting
powers, and he sagaciously foretold the fact, which chemis-
try has since proved, that both these substances had a com-
bustible base, or were of an inflammable nature.
67. Prism. — In the cases of simple refraction just ex-
plained, the ray, after leaving the refracting medium, goes
on in a course parallel to its original direction, because the
65. What is the index of refraction ? Demonstrate this from fig. 61.
66. What substances have highest refraction ? What was New ton'* sug-
gestion about the diamond ?
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50
LIGHT.
Fig. 02.
^b' two surfaces of the medium are pa-
rallel. If, however, the surfaces of the
refracting medium are not parallel,
the raj, on leaving the second sur-
face, will be permanently diverted
from its original path. % The com-
mon triangular glass prism (fig. 62) illustrates this.
As already explained, the ray K is bent toward the
normal in media more dense than air. But in the
prism the emergent ray R is, by the same law,
still farther refracted in the direction R'. By
altering the form of tho surfaces, we may thus
send the ray in almost any. direction, as in the
common multiplying-glass, which gives as many
images as it has surfaces of reflection. In this
way it is that concave metallic mirrors concentrate,
and convex ones disperse a beam of light. Fig. 63
shows the prism conveniently mounted for use.
_____ 68. Analysi&of Light. — By means of the prism,
Pig. 63. ^*r ^saao Newton demonstrated the compound na-
* ture of white light, such as reaches us in the ordi-
nary sunbeam. In
fig. 64 a pencil of
rays from R, fall-
ing from a small
circular aperture
in the shutter of a
darkened room on
Fi& 64# a common trian-
gular prism, is refracted twice, and bent upward toward the
white screen R', placed at some distance from the prism,
where it forms an oblong colored image, composed of seven
colors. This image is called the prismatic or solar spectrum.
The spectrum has the same width as the aperture admit-
ting the beam of light, but its length is greatly increased be-
yond its diameter, the ends retaining the rounded form of
the opening. This image or spectrum presents the most
beautiful series of colors, exquisitely blended, and each pos-
sessing a degree of intensity, splendor, and purity far ex-
ceedingly the colors of the most brilliant natural bodies.
These colors are not separated by distinct lines, but seem to
67. How is light refracted by surfaces not parallel What is tho prism 2
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PRISMATIC COLORS.
61
SOLAR SPECTRUM.
melt into one another, so that it is impossible to say where
one ends and the next begins.
The light from flames of all kinds, the oxy-hydrogen
blowpipe, and the electrio spark, or galvanic light, is also
compound in its nature, like that of the sun and other ce-
lestial bodies.
69. Prismatic Colors. — The colors of the solar spectrum
are in the following order, reading upward : red, orange, yel-
low, green, blue, indigo, violet. These colors are of very
different refrangibility, and for this reason are presented in
a broad and blended surface, the red being the least refracted,
and the violet the most. The seven colors of Newton, it
is believed, are really composed of the three primitive ones,
red, yellow, and blue. This idea is well expressed in th«
following diagram,
(pg. 65.) The three
primitive colors
each attain their
greatest intensity
in the spectrum at
the points marked
at the summit of
the curves; while
the four other co- Fi* 65'
lors, violet, indigo, green, and orange, are the result of a
mixture, in the spectrum, of the first three. A portion of
proper white light is also found in all parts of the spectrum,
which cannot be separated by refraction. We may hence
infer that there is a portion of each color in every part of
the spectrum, but that each is most intense at the points
where it appears strongest. The light is most intense in the
yellow portion, and fades toward each end of the spectrum.
Sir John Herschel has detected rays of greater refrangibi-
lity than the violet of the spectrum and are beyond it, which
have a lavender color. They have this color after concen-
tration, and are therefore not merely, as might be supposed,
dilute violet rays.
If the spectrum is formed by a- beam of light passing
through a slit not over ^th of an inch in width, the image
68. Describe the analysis of light What is the image called ? What
is the form of the spectrum ? How are the colors arranged ? Describe
the blending of the colors from fig. 65. What is lavender light?
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62 LionT.
will be crossed by a great number of dark lines, which al-
ways appear in the same relative position. They are called
the fixed lines of the spectrum, and are much referred to
as boundary lines in optical descriptions.
70. Each of the prismatic colors has some other, which
blended with it produces white light, and hence
is called its complementary color. Let indigo be
regarded as a deeper blue, and each of the three
' primary colors has its secondary colors. Fig.
65 shows the three primary tints blending to
Fig. 65 {bit.) form white light at the centre : at the other
parts the complementary colors are opposite to each other,
e, g. red and green, blue and yellow.
71. Double refraction of light is a phenomenon ob-
served in many crystalline transparent bodies, and is due to
their peculiar structure. It is also seen in bone, shell, horn,
and other similar substances. The beam of light in passing
through such bodies is split into two portions, each of which
gives its own image of any object seen through the doubly
refracting substance. In calcite, carbonate of lime, or Ice-
land-spar, this phenomenon is beautifully seen.
A sharp line, like pq, fig. 66,
when seen through a rhomb of calc-
spar, in the direction of the ray R r,
will seem to be double, a second
parallel line m w, being seen at a
short distance from it, and the dot
o will have its fellow e. In this
Fig. 66. ^gg tne xigHt is represented as com-
ing from E to r, and, passing through the crystal, it is split
and emerges in two beams at e and o. The same effect
would be produced if the light fell so as to strike any part
of the imaginary plane ACBD, which divides the crystal
diagonally and is called its principal section. The axis or
line drawn from A to B is contained in this plane. But
if we look through the crystal in a direction parallel to this
plane (ACBD) there is only simple refraction, and only
one line is seen. One of these beams is called the ordinary
and the other the extraordinary ray. In the case of crys-
tallized minerals, this result is due to the naturally unequal
What lines are seen in the spectrum? 70. What of the colors of na-
tural bodies ? 71. What is double refraction ? Describe fig. 66. What is
the ordinary ray ? Which the extraordinary ? What relation has this
phenomenon to crystallization ?
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POLARIZATION. 58
elasticities of the molecules in the crystals — and it is ob-
served only in those minerals whose molecules are ellipsoidal
— and is wanting in those, like fluor-spar, &c, which belong
to the cube and its derivatives, in which the molecules are
spherical. In well annealed glass, by mechanical pressure, a
sufficient separation of the two rays may be produced to cause
color by interference, though not enough to cause two images
72. Polarization. — The light which has passed one crys-
tal of Iceland-spar by extraordinary refraction is no longer
affected like common light. If we attempt to pass it through
another crystal of the same substance, there will be no fur-
ther subdivision, and only a greater separation of the two
beams. This peculiarity of the extraordinary ray is called
polarization. This interesting phenomenon was accident-
ally discovered in 1808 by Malus, while looking through
a doubly-refracting prism at the light of the setting sun,
reflected from the surface of a glazed door standing at an
angle of about 56° 45', which is the angle at which glass
polarizes light, by reflection.
It is the peculiarity of light which has been polarized
that it will no longer pass through certain substances which
are transparent to common light. Many crystalline sub-
stances possess the power of polarizing light. The mineral
called tourmaline has this property in a remarkable degree.
The internal structure of this mineral is such that a ray of
light which has passed through a thin plate of it cannot pass
through a second, if it is placed in a position at right angles
with the first.
For example, in
the annexed figure
(67) we have two R
thi n plates of tour- — — ' |
maline placed pa-
rallel to each other
in the same direc-
tion. A ray of Fig. 67. Fig. 68.
light passes through
both, in the direction of R R', and apparently suffers
no change : if, however, these plates are so placed as to
cross each other at right angles, as in fig. 68, the ray of light
72. What is polarization ? Who discovered this phenomenon ? What is
the peculiarity of polarized light? Illustrate this from the tourmaline.
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54
LIGHT.
Fig. 70.
is totally extinguished ; and two such points may be found
in revolving one of the plates about the ray as an axis.
73. For illustration, we may suppose the structure of
this mineral to be such that a ray of light
can pass between the ranges of particles in
we direction only, as a fiat blade may pass
between the wires of a bird-
cage, fig. 69, if placed pa-
rallel to them; but will be
arrested by the bars, if presented at right
angles to the wires.
Light is polarized in many ways, as, for
example, by passing through a bundle. of
plates of thin glass or of mica, as in fig. 70,
by reflection from the surface of unsilvered
glass, of a polished table and of most polished
non -metallic surfaces, and at a particular
angle for each. This is plane polarized light
74. The beautiful phe-
nomenon of circular and
elliptic polarization is
seen in many crystalline
bodies. Plates of quartz,
a mineral having one axis,
show the prismatic co-
lors, when viewed by po-
larized light, arranged in
circles and a cross, as in fig. 71;
and by the revolution of the
plane of polarization through 90°,
the colors are changed, and a light
cross (fig. 71) occupies the plane
of the dark one. Nitre gives two
axes of polarization, which in the
revolution of the plane show the
changes seen in figures 73 and
74. Uniaxial crystals uniformly
Fig. 73. Fig. 74. give circular, and binaxial onoa
elliptical figures.
Fig. 71.
Fig. 72.
When is the ray extinguished ? 73. How is this phenomenon explained
in reference to the structure of the crystal? In what ways is light po-
larized? 74. What crystalline bodies give circular, and what elliptical
polarization ? Illustrate this from quartz and nitre.
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LIGHT.
55
75. The chemical power of the son's rays is seen in the
blackening of chlorid of silver, which Scheele long ago observed
to take place much more rapidly in the violet ray than in
any other part of the solar spectrum. It was afterward
observed by Bitter that this blackening likewise occurred
beyond the violet ray, apparently in the dark.
The researches of Neipce, Daguerre, and others, have
greatly enlarged the boundaries of our knowledge on this
subject, and given to the world the elegant arts of the
daguerreotype and photography. The darkening of metallic
salts by light is owing to a peculiar class of rays in the
spectrum, called by Dr. Herschel the chemical ray*, which
are diffused indeed in all parts of the spectrum, but which
are concentrated with more power beyond the violet. This
influence has also been variously denominated actinism!
energia, and tithonicity.
76. The accompanying diagram (fig. 75) will enable the
student to comprehend this subject as at present understood.
From A to B we have the solar
spectrum, with the colors in the
same order as already described.
The cl emical power is greatest
at the violet, and the greatest
heat at the red ray. At b
another red ray is discovered, LA™">rai
and at a is the lavender light. YloLW
The luminous effects are shown ^j,^
by the curved line C, the maxi- blot, . . .
mum of light being found at greet, . ,
the yellow ray. The point of yellow, • .
greatest heat is at D, beyond JJ^;;
the red ray, and it gradually
declines to the violet end,
where it is entirely wanting,
the other limit of heat being
at c. The chemical powers
are greatest about E, in the
limits of the violet, and gra-
dually extend to d, where they
arc lost. They disappear also
Fig. 75.
75. What is the chemical power of the sunbeam ? 70. Illustrate th«
relations of the chemical and other rays, from fig. 75.
Digitized
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56 PHOSPHORESCENCE.
entirely at C ; 4be yellow ray, which is neutral in this re-
spect, attains another point of considerable power at F, in
the red ray, which gives its own color to photographic pic-
tures, and disappears entirely at e. The points D, C, E, there-
fore represent respectively the three distinct phenomena of
Heat, Light, and Chemical Power. This last is. believed to
be quite independent of the other powers ; for all light may
be removed from the spectrum by passing it through blue
solutions, and yet the chemical power remains unaltered.
77. It will readily be perceived that these phenomena
connected with the sunbeam exert no inconsiderable or
unimportant influence in the order of events, whether as
connected with the development of life on our planet, or
with those great physical changes which depend on the
calorific and magnetic agencies that seem inseparably con-
nected with the light and heat of the sun. Plants can
decompose carbonic acid and carry on the functions of
nutrition only under the power of solar light; and the yellow
ray has been shown by Br. Draper to be the one by whose
agency this change is effected in the vegetable kingdom.
78. Phosphorescence is a property possessed by some bodies
of emitting a feeble light, often at ordinary temperatures.
The diamond and some other substances, after being exposed
to the rays of the sun, will emit light for some time in the
dark. Fluor-spar, feld-spar, and some other minerals, give
out a fine light of varied hues, when gently heatea or
scratched. Oyster-shells which have been calcined with
sulphur and exposed to the sunlight, will shine in a dark
place for a considerable time afterward, and even an electrical
spark will renew this emanation. The glow-worm, the fire-
fly, rotten wood, decaying fish, and various marine animals
possess the same power, although in these cases the cause is
probably different from that which excites the same pheno-
menon in crystallized bodies.
77. "What consequences follow the phenomena described? 78. What if
pho*i>horescence ?
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HEAT. 57
III. HEAT.
Sources and Properties of Heat
79. The phenomena of Heat, or Caloric, are emineLtly
interesting to the chemical student. They may be discussed
under two general divisions: 1. The Physical; and, 2. The
Chemical. Under the first head are included the communi-
cation of heat, by radiation, by conduction, and convection ;
the transmission of heat by various substances, and the
phenomena of expansion, including thermometers and pyro-
meters ; and lastly, specific heat. Under the second head are
placed the changes produced by heat in the states of bodies ;
for example, liquefaction and latent heat of liquids, vapor-
ization and latent heat of vapors, liquefaction of gases,
natural evaporation and congelation, density of vapors, and
so forth.
80. The sources of heat are chiefly the sun, combustion,
and chemical changes; friction, electricity, vitality; and,
lastly, terrestrial radiation.
Solar heat, as is well known, accompanies the sun's light,
and it unquestionably results from the intensely high tem-
perature of the sun itself. It is believed that the sun's
rays do not heat the regions of space, and the earth's
atmosphere 'is heated almost entirely by contact with the
surface of the heated earth. A portion of the sun's heat is
however taken up by the air before the rays reach the earth.
Combustion and chemical change, including vital heat,
are sources of heat, limited by the quantity of matter suffer-
ing change, and to the time in which the change takes place.
The stores of fossil fuel laid up in the coal formations and
the vegetable combustibles now on the earth's surface may
be considered as a result of the sun's action through the
powers of vegetable life.
Friction causes heat, as a result of mechanical motion.
The heat of friction continues as long as the mechanical
power required to produce motion is maintained. No
change of state or loss of weight is necessarily experienced
79. What is said of heat? How is the subject discussed? 80. What
are the sources of heat ? What of solar heat ? What of combustion ?
What of friction?
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68 HEAT.
in the substances employed. Count Rumford showed that
in the boring of cannon under water, the heat evolved was
so considerable as to bring the water, in a short time, to the
boiling-point The same observer succeeded in warming a
large building by the heat evolved from the constant move*
ment of large plates of cast-iron upon each other. Friction-
heat may be regarded as the equivalent of the motion pro*
ducing it The heat of the electrical spark and of the
galvanic current will be considered elsewhere.
81. Terrestrial radiation is a constant source of heat,
escaping from the interior of the earth, and has doubtless
some effect in modifying the climate of our globe. Geolo-
gists consider it proved that the earth has cooled to its pre-
sent condition from a state of intense ignition, and that this
state still remains in the interior, at no very considerable
distance from the surface. All deep mines and Artesian
wells show a constant and progressive increase of temperature
in going down, and below the line of atmospheric influence.
The Artesian well in the yard of the great Grenelle slaughter-
house, in Paris, is 2000 feet deep, and the water rises with a
temperature of 85° degrees Fahrenheit. At Neusalzwerke,
in Westphalia, is a well 2200 feet deep, and its water has a
temperature of 91°. The average increase of temperature
from this cause is estimated to be 1°8, for every hundred
feet of descent. Assuming this ratio, we shall have at two
miles the boiling-point of water ; and at about twenty-three
miles, or only Tg0th of the earth's radius, there must be a
temperature of near 2200 degrees of Fahrenheit At this
heat, cast-iron melts, and trap, basalt, obsidian, and other
rocks are perfectly fluid. The geological importance of these
facts is self-evident ; and we cannot fail to remark here an
efficient cause for all hot-springs.
82. Properties of Heat — Heat is invisible and impon-
derable. It proceeds, like light, in rays, with great but
hitherto undetermined velocity. The intensity of heat-rays
varies inversely as the square of the distance . from the
source of heat. Kays of heat, like those of light, may be
concentrated from a metallic mirror, but not from those of
glass, as this substance absorbs heat very largely. They are
81. What is said of terrestrial radiation ? What is determined in deep
wells? What is the rate of increase ? At what depth would iron melt?
32. What are the properties of heat? How is it like light?
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COMMUNICATION OP HEAT. 59
also of various refrangibility, and capable of double refrac-
tion and polarization. Therefore, they move in waves 01
undulations. Heat is self-repellant, as two bodies heated in
vacuo repel each other. It is communicated by conduction
and by convection as well as by radiation. It is variously
absorbed and transmitted by various substances, and pro-
duces different degrees of expansion, varying with the nature
of matter affected. Lastly, it determines the phenomena
of congelation, liquefaction, and vaporization. The physio-
logical sensation of cold and heat experienced in our per-
sons is not to be confounded with the physical and chemical
phenomena of heat now to be discussed. This sensation is,
within certain limits, entirely relative. For example, if one
hand is plunged in a vessel of iced-water and the other into
moderately warm water, a strong contrast is evident imme-
diately ; but if we suddenly transfer both hands to a third
vessel of water, at the common temperature, our sensations
are instantly reversed. The third vessel is warm as com-
pared with ice-water, and cold compared with the tepid
water.
Communication of Heat.
83. Heat is communicated from a hot body, 1. By radia-
tion, or transmission of rays of heat in all directions ; 2.
By contact of the atmosphere conveying it away, (convec-
tion ;) and, 3. By communication to the substance support-
ing it, (conduction.) By one or all these modes, a body
placed in vacuo or in the air, and differing in temperature
from surrounding bodies, gradually regains the equilibrium
of temperature. If hot, it loses, and surrounding bodies
gain ; if cold, it gains at the expense of those substances
having a higher temperature.
84. Radiation takes place from all bodies wherever there
is a disturbance of equilibrium, but in very various degrees,
according to the nature of the body and of its surface. All
bodies have a specific radiating and absorbing power in
respect to heat. To these the retaining and reflecting
powers are strictly opposed. Radiation takes place in a
vacuum more easily than in air, and is, therefore, quite
WTiSt i» said of the sense of heat and eold? Give an illustration.
S3. How is heat communicated ? 84. How does radiation happen ?
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60
HEAT.
independent of any conducting medium.
Rays of heat may be concentrated by the
parabolic metallic mirror. All rays of
heat or light falling on this form of mirror
are collected at F, the focus, (fig. 76,) and
a hot body placed there will have its rays
sent forth in parallel straight lines, as
shown in the figure. A second and similar
mirror may be so placed as to receive and
collect in a focus all the rays proceeding
from any body in the focus of the other,
Fig. 76. where they will become evident by their
effect on the thermometer. If the hot body be a red-hot
cannon-ball, and the mirrors are carefully adjusted, so as to
be exactly opposite each other in the same line, the accumu-
lation of heat in the focus of the second mirror is such as
to inflame dry tinder, or gunpowder, even at many feet
distance.
85. This striking experiment is shown by the conjugate
mirrors, arranged as
in fig. 77. Ice placed
in the focus of one of
the mirrors will de-
press a thermometer
in the other focus, —
not because cold is
__ radiated, (as cold is 9
FlS-^* mere negation,) but
because in this case the thermometer is the hot body and
parts with its heat to fuse the ice. A thermometer sus-
pended midway between the two mirrors is not affected. A
plate of glass held between the mirrors will cut off the calorific
rays — thus proving a difference of penetrating power be-
tween the rays of heat and of those of light. As soon aa
the screen is raised the phosphorus in the focus is inflamed.
86. Radiation and Absorption of heat are exactly equal
to each other in a given • surface, but, as before stated,
the nature of the substance and of the surface have much
influence in these respects. All black and dull surfaces ab-
sorb heat very rapidly when exposed to its action, and part
How does a metallic mirror affect heat ? 85. Describe the experiment
tn fig. 77. 86. What of absorption? How does color affect it?
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CONDUCTION OP HEAT 61
with it again by secondary radiation. The sun shining on
a person dressed in black is felt with much more power than
if he were dressed in white. The former color rapidly
absorbs heat, while from the latter a considerable part of it
is reflected. The color of bodies has, however, nothing to
do with their radiating powers, and one colored cloth is as
warm in winter as another, as regards the emission of heat.
(Bache.)
If the radiating power of a surface covered with lamp-
black be assumed as 100, that of a surface covered with
Indian ink will be 88, with ice 85, with graphite 75, with
dull lead 45, with polished lead 19, with polished iron 15,
with polished tin, copper, silver, or gold, 12. (Leslie.)
Hence the polished metallic vessel, which is so well adapted
to retain the heat of boiling water, is the very worst vessel
in which to attempt to boil it. The sooty surface next the
fire, however, transmits heat with the greatest rapidity. In
the experiment with the mirrors just described, the polished
surfaces remain cool, reflecting nearly all the heat which
falls upon them. A glass mirror in the same experiment
would be useless, as glass absorbs nearly all the heat, of low
intensity, which falls upon it.
87. The formation of dew is owing to radiation, cooling
the surface of the earth so rapidly, that the moisture of the
air, which is always abundant in summer, is condensed upon
it : as we see it on the outside of a tumbler of iced-water in
a hot day. Radiation takes place more rapidly from the
surface of grass and vegetation than from dry stones or
dusty roads : for this reason, plants receive abundant dew,
while the barren sand has none.
88. Conduction of heat. — A metallic bar placed by one
end in the fire, slowly becomes hot, the heat being trans-
mitted by conduction, from particle to particle. Each so-
lid has its own peculiar rate of conducting heat, but
in all it is a progressive operation, the heat seeming to
travel with greater or less rapidity, according to the nature
of the solid. If we hold a pipe-stem or glass rod in the
flame of a spirit-lamp or candle, we can heat it to redness
within an inch of our fingers without inconvenience ; but a
wire of silver or copper held in the same manner soon be-
Give some results of radiation from different substances. 87. How it
dew formed ? 88. What is conduction ? Why docs it fall on plants ?
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62 HEAT.
comes too hot to hold. This is owing to an inherent di£
ference in these solids, which we call conducting power. The
. progress of conducted
~ ° ° c ° 0 IT heat in a 80lid is ea8i"
W ly shown, as in fig. 78,
e' representing a rod of
copper, to which are stuck by wax several marbles at equal
distances ; one end is held over a lamp, and the marbles
drop off, one by one, as the heat melts the wax; that
nearest the lamp falling first, and so on. If the rod is of
copper, they all fall off very soon ; but if a rod of lead or
platinum is used, the heat is conveyed much more slowly.
Little cones of various metals and other substances may be
tipped with wax or bits of phosphorus, as
shown in fig. 79, and placed on a hot surface.
The wax will melt, or the phosphorus inflame,
at different times, according to the conducting
Pig. 79. p0wer 0f the various solids. A screen is
needed to cut off the radiant heat, which would otherwise in-
flame the phosphorus prematurely. Accurate experiments
have been made, which have enabled us to arrange most so-
lids in a table showing their conducting powers. The metals,
as a class, are good conductors, while wood, charcoal, fire-clay,
and similar bodies are bad ones. Thus gold is the best con-
ductor, and may be represented by the number 1000 ; then
marble will be 23*5, porcelain 12, and fire-clay 11. Metals,
compared with each other, are very different in conducting
power. Thus —
Gold 1000
Silver 973
Copper 898
Platinum. 381
Iron 375
Zinc 363
Tin 304
Lead 180
89. Vibrations occur in masses of metals and other sub*
stances when conducting heat, which seem to indicate the
production of waves or undulations among the particles.
Mr. Trevellyan has remarked that if a mass of warm brass
is placed on a support of cold lead, the rounded surface of
What is its rate in different substances ? 89. How is an undulation
proved to exist in heated bodies ? Mention Trevellyan and Page's ex-
periments.
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CONDUCTION OF HEAT. 63
the brass resting on the flat surface of the lead, the brass
bar is thrown into a series of vibrations, accompanied by
a distinct sound and a rocking motion. of the brass, until
equilibrium is restored. Dr. Page has shown that a current
of galvanic electricity passed through a similar apparatus
produces the same results. Fig.
80 shows Page's apparatus, in
* which a feeble current of electri-
: city produces a rocking motion of
' the metallic masses resting on the
bars of brass. The best effects are
Fig. 80. produced between good and bad
conductors of heat, the former being the hot bodies.
90. Heat is conducted in crystallized bodies, in curves
springing from the sources of heat. In plates of homoge-
neous substances these curves are circles ; in those of a crys-
talline texture, belonging to the rhombohedral system, the
curves are ellipses of very exact form, whose longer axes are
in the direction of the major crystalline axis — proving the
conducting power of such bodies to be greatest in that direc-
tion. The mode of experimenting in such cases is to cover
the surface of the crystalline plate with wax, heat very gra*
dually, and watch the lines of fusion on the surface.
91. The sense of touch gives us a good idea of the dif-
ferent conducting power of various solids. All the articles
in an apartment have nearly the same temperature ; but if
we lay our hand on a wooden table, the sensation is very dif-
ferent from that which we feel on touching the marble
mantel or the metal door-knob. The carpet will give ua
still a different sensation. The marble feels cold, because it
rapidly conducts away the heat from the hand j while the
carpet, being a very bad conductor, retains and accumulates
the heat, and thus feels warm. Clothing is not itself warm,
but, being a bad conductor, retains the heat of the body. A
film of confined air, is one of the worst Conductors; loose
clothes are therefore warmer than those which fit closely.
For the same reason, porous bodies, like charcoal, are bad
conductors ; and a wooden handle enables us to manage hot
bodies with ease.
92. The conducting power of fluids is very small. A
90. How is heat conducted in crystals ? 91. What does touch inform
ns of? 92. What of the conducting power of fluids ?
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64
HEAT.
simple and instructive experiment will prove this satis-
factorily. A glass, like that in fig. SI,
is filled nearly to the brim with water.
A thermometer-tube, with a large ball,
is so arranged within it that the ball
is just covered with the water: the
stem passes out at the bottom through
a tight cork, and has a little colored
fluid, L, in it, which will, of course,
move with any change of bulk in the
air contained in the ball.
Thus arranged, a pointer I marks
exactly the position of one of the drops
) of enclosed fluid, when a little ether is
poured on the surface of the water,
and set on fire. The flame is intensely
hot, and rests on the surface of the
water; the column of fluid at I is,
however, unmoved, which would not
be the case if any sensible quantity of
heat had been imparted to the water.
The warmth of the hand touching the
ball will at once move the fluid at I,
by expanding the air within. By heat-
ing a vessel of water on the top, then,
s we should never succeed in creating any
] thing more than a superficial elevation
' of temperature : at a small depth the
Fig. 81. water would remain cold. Liquids do
possess a very low conducting power, contrary to the opinion
of Count Rumford, and heat appears to be propagated in
them by the same law as in solids, when care is taken to
avoid the production of currents.
93. The conducting power of gases is also very small.
Heat travels with extreme slowness through a confined
portion of air. This is a very different thing from the con-
vection of heat in gases, which we will presently explain.
Double windows and doors, and furring (so called) of plas-
tered walls, afford excellent illustrations of the slow con-
duction of heat through confined air. Wc have no proof
that heat can be conducted in any degree by gases and va«
Explain the experiment, fig. 81. What of the conducting power of gases t
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CONVECTION OF HEAT.
65
pors. To illustrate the relative conducting powers of solids,
fluids, and gases : if we touch a rod of metal heated to 120°,
we shall be severely burned ; water at 150° will not scald,
if we keep the hand still, and the heat is gradually raised ;
while air at 300° has been often endured without injury.
The oven-girls of Germany, clad in thick socks of woollen,
to protect the feet, enter ovens without inconvenience whero
all kinds of culinary operations are going on, at a tempera-
ture above 300° ; although the touch of any metallic article
while there would severely burn them.
94. Convection of heat is its transportation, as in liquids
and gases, by the power of currents.
Heat applied from beneath to a vessel
containing water, warms the layer or
film of particles in contact with the
vessel. These expand with the heat,
and consequently, becoming lighter,
rise, and colder particles supply their
place, which also rise in turn, and
so the whole contents of the vessel
come in quick succession into con- 1
tact with the source of heat, and
convey it through the mass. This
is well illustrated in fig. 82, which
shows how water acts in a vessel of
glass, when heated at a point be-
neath by a spirit-lamp. Each par-
ticle in turn comes under the in-
fluence of heat, because of the per-
fect mobility of the fluid. A series
of such currents exists in every
vessel in which water is boiled, and
they are rendered more evident by throwing into it a few
grains of some solid (like amber) so nearly of the same
gravity of water that it will rise and fall with the currents.
95. In the air, and in all gases and vapors, the same
thing happens. The earth is heated by the sun's rays, and
the Sim of air resting on the heated surface rises, to be re-
placed by cold air. The rarefied air may be easily seen, on
a hot day, rising from the surface of the earth, being made
Fig. 82.
94. What is convection ? Illustrate it in water. 95. How is heat distri
outed in air.
6
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J
W HEAT.
visible b> its different refractive power. Hence arise man?
aerial currents and winds. The currents of the ocean art
also influenced by the same cause.
Transmission of Heat.
96. Light passes through all transparent bodies alike,
from what source soever it may come. The rays of heat
from the sun also, like the rays of light from the same lu-
minary, pass through transparent substances with little
change or loss. Radiant heat, however, from terrestrial
sources, whether luminous or not, is in a great measure ar-
rested by many transparent substances. If the sun's rays be
concentrated by a metallic mirror, the heat accompanying
them is so intense at the focus as to fuse copper and silver with
ease. A pane of colorless window-glass interposed between
the mirror and the focus, will not stop any considerable part
of the heat. If the same mirror is presented to any other
source of heat, however, (as, for example, to the red-hot ball,
85,) the glass plate will stop nearly all the heat, although
the light is undiminished. We thus distinguish two sorts of
calorific rays, which are sometimes called Solar and Culinary
Heat; and we discover that substances transparent to light
are not, so to speak, transparent to heat in a like degree.
This property is distinguished from transparency by the term
Diathermancy y (meaning the easy transmission of heat.) It
appears that many substances are eminently diathermous,
which are almost opake to light; like smoky quartz, for
example. The temperature of the source of heat has the
greatest influence on the number of rays of heat which are
transmitted by a given screen ; as in the case of the glass
plate, which permits nearly all the sun's rays to pass, but
arrests over 65 per cent, of the rays from a lamp-flame.
97. Our knowledge on this subject has been derived almost
entirely from the researches of M. Melioni, of Naples. This
philosopher, by the use of a peculiar apparatus, called the
thermo-electric pile, was able to detect differences of tempera-
ture altogether inappreciable by common thermometers. Thif
instrument is an arrangement of little bars of the two metals,
96. Distinguish transmission of heat from that Qf light. What if
diathermancy ? What was Melloni's research ?
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TRANSMISSION OF HEAT.
67
Fig. 83.
antimony and bismuth, about fifty of which are sol-
dered together by their alternate ends, the whole
being, with its case, not more than 2} inches long,
by J to t of an inch in diameter. The least differ-
ence of heat between the opposite ends of this little
battery will produce an electrical current capable of influenc-
ing a magnetic needle in an instrument called a galvanomC'
fer,(§202.) The needle of the galvanometer will move in exact
accordance to the intensity of the heat. This is so delicate
an instrument, that the radiant heat of the hand held near
the battery will cause the needle to move some 10° over its
graduated circle. In fig. 84, a is the source of heat, (an oil-
Pig. 84.
lamp in this case,) b a screen having a hole to admit the
passage of a bundle of rays; c is the substance on which the
heat is to fall ; d the thermo-multiplier, or battery, which is to
receive the rays after they have passed through the substance
c. Two wires connect the opposite members of this battery
with the galvanometer e, which, for steadiness, is placed on
a bracket attached to the wall. Thus arranged, and with
various delicate aids which we cannot here explain, a vast
number of most instructive experiments have been made on
radiant heat from different sources, and its effect ascertained
on various substances. Four different sources of heat were
employed : 1. The naked flame of an oil-lamp ; 2. A coil of
platinum wire heated to redness by an alcohol-lamp; 3. A
surface of blackened copper heated to 734°; and, 4. The
same heated to 212° by boiling water. The first two of
these are luminous sources of heat, the last two non-luminous.
98. As already stated, the temperature of the source
97. What are Mellonfs researches? Describe the arrangement in figs.
83 and 84.
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«8
HBAT.
greatly influences the number of rajs transmitted. Thai
which has passed through ono plate of rock-salt has less
liability to be arrested by a second, still less by a third, and
so on.
The following table will show a few of the principal re-
sults : —
Names of interposed substances, common
0.102 inch.
Transmission of 100
rays of heat from
2
1^
Rock-salt, transparent and colorless...
Iceland-spar
Plate-glass
Rock-crystal
Rock-crystal, brown
Alum, transparent
Sugar-candy ,
Ice, pure and transparent
Thus it appears that rock-salt is the only substance which
permits an equal amount of heat from all sources to pass.
In other cases, the number of rays passing seem proportioned
to the intensity of the source. M. Melloni has called rock-
salt the glass of heat, as it permits heat to pass with the same
ease that glass does light. It is supposed that the difference
found by experiment in the diathermancy of bodies is owing
to a peculiar relation which the various rays of heat sustain
to these bodies, analogous to that difference in the rays of
light which we call color. Thus all other bodies, except salt,
act on heat as colored glasses act on light, entirely absorbing
some of the colors, and allowing others to pass. In this
view, rock-salt may be said to be colorless as respects heat,
while alum and ice are in the same sense almost back.
Opake bodies, like wood and metals, entirely prevent the
transmission of heat ; but dark-colored quartz crystal is seen,
by the table, to differ only 1 from white crystal, and even
perfectly black glass does not entirely stop all heat.
99. By cutting rock-salt into prisms and lenses, the heat
from radiant bodies may be reflected, refracted, and concen-
98. What substance transmits heat most readily? Which least so?
What is rook-salt called ? 99. How is heat polarized, Ac ?
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EXPANSION. 69
trated, like light, and doubly refracting minerals; like Ice*
land-spar, will polarize it.
Expansion of Bodies by HeaL
100. All bodies expand with an increase of hoat, and
diminish with its loss. The expansion of a solid may be
shown by a bar of metal which, as in
the fig. 85, is provided with a handle,
which at ordinary temperatures ex-
actly fits the gauge. On heating this
over a spirit-lamp, or by plunging it
into hot water, it will be so much
expanded in all its dimensions as no
longer to enter the gauge. On cool-
ing it with ice, it will again not only
enter freely, but with room to spare.
The same fact is shown by a ball, to
which, when cold, a ring with a han-
dle will exactly fit; but on heating Fig. 85.
the ball, the ring will no longer encircle it.
The expansion of & fluid may be shown by filling the bulb*
of a large tube (fig. $6) with coloured water to a mark on
the stem. On plunging the bulb into
hot water, the fluid is seen to rise rapidly
in the stem. If it be cooled by a mix-
ture of ice and water, it is seen to sink
considerably below the line. A similar
bulb (fig. 87) filled with air, and hav-
ing its lower end under water, is ar-
ranged as in the figure, to show the '
expansion of air by heat. The warmth
of the hand applied to the naked ball
will be sufficient to cause bubbles of air
to escape from the open end through!
the water ; and on removing the hand,
the contraction of the air in the ball, Fi* *•• Fi«* 8r-
from the cooling of the surface, will cause a rise of the fluid
in the stem, corresponding to the volume of air expelled, as
100. What if expansion t niuitrate it for a solid. For a liquid. Fo*
a gas.
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70
HEAT.
shown in the figure. The slightest change of temperature
will cause this column of fluid to move, as the air expands
or contracts. In fact, it is the old air-thermometer.
101. Expansion of Solids. — Expansion by 'heat varies
greatly: 1. According to the nature of the substance ; and,
2. Not in degree only, but also in the law which it follows.
In solids, between the freezing and boiling of water, the rate
of expansion in the same solid is equal for each additional
degree. In experiments on this subject, rods of equal length
are used, composed of the various subjects of experiment,
whose expansion in length is accurately measured.
In fig. 88, the
rod t is confined
by a, so that its
free end bears
against b. Heat-
ed by an alcohol
lamp, or other
source of heat, it
!_ expands and car-
ries forward the
Fig. ss. index g over the
graduated arc c. On cooling, it contracts, and the spring a
moves the index back again to the starting point. This
linear expansion, multiplied by 3, gives the expansion in
volume very nearly. Thus, for example, in the following
solids, when heated from 32° to 212° Fahrenheit, the ex-
pansion is —
In Length.
In Bulk.
339 parts of zinc
349
523
583
643
810
921
1006
1113
2831
lead
silver
copper
gold
iron
antimony
platinum
white glass
black marble
340 or 112 parts — 113
— 350 « 116
— 524 « 174
— 584'
— 644
— 811
— 922
= 1007
1114 " 371
= 2832 «
« 194
" 217
" 270
" 307
" 335
943
— 117
" — 175
" ^=195
« =-218
« —271
" — 308
" —336
" —372
" —944
102. The expansion of fluids is ether apparent or absolute,
according as the dilatation of the containing vessel is or is not
101. What is the rate of expansion in solids ? Describe fig. 88. Gire
•samples from table, in length and bulk.
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EXPANSION.
71
taken into account. This fact may be m*
illustrated in the annexed apparatus, (fig.
89,) where a tube of glass is bent twice at
right angles, the open ends a and b upper-
most; a larger tube surrounds each, leaving
two cells, in which water of different tem-
peratures may be poured. The inner tube
is filled, for example, with colored water,
of the ordinary temperature, to the level P;
hot water is now poured into the outer cell
of bj when an immediate elevation of level
in the colored fluid is seen to m. This is
on the principle that the heights of columns
of liquids in equilibrium are inverse to their
densities. In this manner it has been de-
termined that in heating from 33° to 212°,
9 measures of alcohol becomes 10 ; of water,
23 measures becomes 24 ; and of mercury, Flg* 89#
55 measures becomes 56. Thus it happens that in the com-
mon changes of the seasons the bulk of spirits varies about
5 per centum. It has been determined, also, that liquids
are progressively more expansible at higher than at lower
temperatures. The liquefied gases illustrate this law in a
remarkable manner, for fluid carbonic acid, as observed by
M. Thilorier, has a dilatation four times greater than is ob-
served in common air at the same temperatures. The law
of expansion in liquids is not yet well made out.
103. Unequal Expansion of Water. — The general law of
expansion for nearly all solids and fluids, especially within
the limits of the freezing and boiling points of water, is,
that each solid or fluid expands, or contracts, an equal amount
for every like increase, and reduction of, temperature, each
body having its own rate of dilatation. There are, how-
ever, some exceptions to this law, of which water offers a
remarkable example. As the comfort, and even habitability
of our globe, are in a great degree dependent on this excep-
tion to the ordinary laws of nature, it is worthy of special
notice.
If we fill a large thermometer-tube or bulbed glass (fig. 90)
with water, and place it in a freezing mixture, where wo
102. Describe the apparatus fig. 89. What is the expansion of water?
Of alcohol ? 103. What inequality in the expansion of water ?
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72 HEAT.
can observe the fall of the temperature by tin
thermometer, we shall see the column descend
A regularly with the temperature, until it reaches*
11 39*°1 F., when the contrary effect will take place:
|| the water then begins suddenly to rise in the tube,
|| by a regular expansion, until the temperature
—II — falls to 32°, when so sudden a dilatation takes
I place as to throw the water in a jet from the open
I orifice. If, on the other hand, we heat water in
^L such an apparatus, commencing at 32°, we shall
M^ find that, until the temperature rises to 40°, the
^^r fluid, in place of expanding as we might expect,
Kg. 90. will actually contract Water has, therefore,
its greatest density at 39°-5, and its density is
the same for equal temperatures above and below this point;
thus we shall find it having a similar density at 34° and 45°.
104. Beneficial Result*. — Let us now observe what useful
end this curious irregularity in the expansion of water sub-
serves. When winter approaches, the lakes and rivers, by
the contact of the cold air, begin to lose their heat on the
surface; the colder water, being more dense, falls to the bot-
tom, and its place is supplied by warmer water rising from
below. A system of circulation is thus set in motion, and
its tendency, if the mass of water is not too large, is to reduce
the whole gradually to the same temperature throughout.
When, however, the water has cooled to 390,5, this circula-
tion is arrested by the operation of the law just explained :
below this point the water no longer contracts by cooling,
and of course does not sink; but on the contrary expanding,
as before explained, it becomes relatively lighter, and remains
on the surface : the temperature of this layer or upper stratum
gradually falls, until the freezing point is reached, and a
film of ice is formed. But as ice is a very bad conductor,
the heat now escapes with extreme slowness; all currents
tending to convey away the cooler parts of the water are
arrested, and the thickness of the ice can increase only by
the slow conduction through the film already formed : the
consequence is, that our most severe winters fail to make ice
of any great thickness. Other causes, also, which we shall
What is its maximum density ? 104. What beneficial result follows ?
Why is freezing a flow process ? Describe the mode of freezJbg of lakes
and rivers.
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EXPANSION. TJ
presently explain, co-operate at all times to render the freez-
ing of water a very slow process. We cannot fail to be im-
pressed by the wisdom of that Power, which not only frames
great general laws for the government of matter, but also
makes exceptions to them, when the welfare of His creatures
requires them.
105. The expansion of all gate* and vapours is the same
for an equal degree of heat, and equal increments of heat
produce equal amounts of expansion. The rate of expansion
amounts to 7^th part of the volume of the gas at 0Q for
each degree of Fahrenheit's scale, or between 32° and 212°
to 0*366, or more than i of the initial volume of the gas.
When gases are near the point of compression at which
they become liquid, this law becomes irregular, and is not
strictly true for all gases ; but the departures from the law
are so small that we need not mention them here.
106. Practical application of the laws of expansion in
solids are frequently made with great advantage in the arts.
The rivets which hold together the plates of iron in steam-
boilers are put in and secured while red-hot, and on cooling
draw together the opposite edges of the plates with great
power. The wheelwright secures the parts of a carriage-
wheel by a red-hot tire, or belt of iron, which being quickly
quenched, before it chars the wood, binds the whole fabric
together with wonderful firmness. The walls of the Con-
servatory of Arts, in Paris, after they had bulged badly, were
safely drawn into a vertical position, by the alternate con-
traction and expansion of large rods of iron passed across it,
and so secured by screw-nuts and heated by Argand lamps
as to draw the walls inward. Towers of churches and other
buildings have been thrown down or otherwise injured by
the expansion of large iron rods (anchors) built into the
masonry with the design of strengthening them. The Bun-
ker Hill monument is daily bent out of a perfect vertical
by the heat of the sun expanding the granite of which it
is built. The mechanical arts are, in fact, full of beautiful
applications of the principles of expansion. Among these
we may mention
107. The Compensation Pendulum, adapted to regulating
the rate of time-pieces. The length of the pendulum is
106. What is the law of expansion in gases ? How muoh does air dilate
for each degree ? 106. Mention some instances of expansion in the arte*
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n
HEAT.
altered by variations of temperature, and of course the rata
of the clock is disturbed. A perfect compensation for this
error is obtained by the use of a compound
pendulum of brass and iron, or other two
metals, arranged as is shown in fig. 92, in
such a manner that the expansion of one
metal downward will exactly counteract that
of the other metal upward; thus koeping
the ball of the pendulum at a uniform dis-
tance from the point of suspension. The
shaded bars represent the iron, and the light
ones the brass. The same object is accom-
plished by using mercury, as shown in fig.
91, contained in a glass or steel vessel at the
end of the pendulum-rod. The expansion
which lengthens the rod also increases the
m volume of the mercury; this increase of bulk
J) in the mercury raises the centre of gravity to
jtt £_J an exactly compensating amount, and the
Fig. 91. F^92 c*ock remains unaltered in rate. Watches and
' chronometers are regulated by a like beautiful
contrivance. The balance-wheel, (fig. 93,) on whose uniform
motion the regularity of the watch or chronometer depends,
is liable to a change of dimensions from
heat or cold. If made smaller, it will
move faster, and if larger, slower. To
/^ ^\ avoid this error, the outside of the wheel
IV" vl/"- ji is made of brass, the inside of steel, and
vW ffl cut afc two °PP0S*te Pomt8 ; one end of
^^. ^^ each part is screwed to the arm, and the
^^^■^^^ loose ends of the rim, being united by a
Fig. 93. screw, are drawn in or thrown out by
the changes of temperature, in precise proportion to the
amount of change ; thus perfectly adapting the revolution
of the wheel to the force of the spring. The principle of
this wheel, it will be seen, is the same as in the compound
bars, (107.) A pendulum of pine-wood is sometimes em-
ployed for clocks, because it is so little changed by varia-
tions of temperature.
108. The unequal expansion of solids is well shown by
107. What is the compensation pendulum? What the mercurial?
What is the compensation balance ?
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THE THERMOMETER.
75
joining firmly, by rivets, two bars, one of iron and one of
brass, as in fig. 94. When
they are heated, the brass
expanding most, will canse
the compound bar to bend,
as shown in the fig. 95.
If they are cooled by ice,
the brass contracting most,
^
Fig. 94.
Kg. 95.
will bend the united metals in an opposite direction,
The Thermometer.
109. The Thermometer is an instrument for measuring
heat by the expansion of various liquids and solids. This in-
strument was invented by Sanctorio, an Italian, in A. d. 1590.
His was an air-thermometer, such as is figured in the context.
A bulb of glass with a long stem is placid with its
mouth downward, in a vessel containing a portion
of colored water, (fig. 96.) A part of the air
being first expelled from the ball by expansion, the
fluid rises to a convenient point in the stem, to which
is attached a scale of equal parts, with degrees or
divisions marked by some arbitrary rule. Thus
arranged, the instrument indicates with great deli-
cacy any limited change of temperature in the sur-
rounding air. The portion of air confined in the
ball, when heated, expands, and pressing on the
column of fluid in the stem, drives it down, accord-
ing to the amount of expansion or the degree of
heat; and the reverse results from a decrease of
temperature. The air thermometer has given place to Fl*' 96,
110. The Common Thermometer. — This instrument indi-
cates changes of temperature by the expansion of mercury or
of alcohol contained in the bulb blown upon the end of a very
fine glass tube. Mercury possesses very remarkable properties
fitting it for a thermometric fluid : it may easily be obtained
pure ; its rate of expansion is singularly uniform between
its boiling and freezing points, and the range of temperature
between these points is greater than in any other fluid, (about
660° Fahr.) For very low temperatures alcohol is preferred,
as it has never yet been solidified, even with the intensest
108. Describe figs. 94 and 95. 109. What is the thermometer? De-
scribe Sanotorio's thermometer. 110. Describe the common thermometer.
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76
HEAT.
artificial cold of the carbonic acid bath (§151,) or of the arctic
regions. The precautions needed to make a thermometer,
such as will meet the demands of modern science, are too
numerous to be fully described here. Suffice it to say, that
by expanding the air in the empty ball, while the open end
of the tube is covered with mercury, a portion of it is carried
in by the pressure of the atmosphere, and by boiling this,
. all air is expelled and the tube entirely filled
™
■MS
9 a
g.i
Fig. 97.
£ with mercury. The quantity is so adjusted
by trial that it will stand at a convenient
height in the tube. Finally, the tube is sealed
by the lamp, while the contained mercury is
expanded to completely fill it. The empty
space in a good thermometer is therefore a
torricellian vacuum.
111. Graduation of Thermometers. — The
scales adapted to the thermometer in various
countries are divided into arbitrary degrees,
and, unfortunately for science, the scales differ
widely. There are, however, two fixed points
in all, which are determined by direct ex-
J periment. These are the boiling and freezing
points of water, or, more accurately, the melt-
ing point of ice. The space between these
- 1^: two points is divided into a certain number
: of equal parts, according to the scale to be
; : employed. In France, and on the continent
of Europe generally, the scale of Celsius, or
Centigrade, is employed, which divides this
space into 100 degrees. In England and
£j America the scale of Fahrenheit, a Hollan-
der, is adopted. This scale adopts for its
: zero point the cold produced by a freezing
mixture of snow and salt; which its author
assumed to be the greatest possible cold. The
word zero signifies nothing, but we know that
as cold is the mere absence of heat, it is hope-
less to expect an absolute zero. The scale
:ij±: of Reaumur, adopting the melting of ice as
: zero, divides the space between that point and
the boiling of water into 80 degrees. The
111. How are thermometers graduated ? What are fixed points ?
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THE THERMOMETER. 77
scale of De Lisle, which is no longer used, read downward
from zero at boiling water to 150°, the freezing of the same.
Annexed, in fig. 97, we have these four scales compared. It
will be seen that zero Centigrade is zero Reaumur and 32°
Fahrenheit; while 100° ,C. = 80° R. =212° F. In other
words, these three scales divide the space between the two
fixed points respectively into 100° C, 80° R., and 180° F. ; or,
reducing to smallest terms, 5° C. = 4° R .= 9° F. To reduce
Centigrade to Fahrenheit, we can multiply by 9 and divide
by 5, and add 32° to the quotient, and vice versa. Suppose
we wish to know what 70° C. is on Fahrenheit's scale; we
have the proportion 5 : 9 : : 70° : 126°. If we add 32°, which
is the difference between zero of F. and C, we have 126° +
82° = 158°, which is the number required, for 70° C. =
158° F. In stating thermometrical degrees, the sign + i*
used for points above zero, and — for those below. Fahren-
heit's scale is the one employed in this work.
112. The SfUf'Registering Thermometer is a form of the
instrument contrived for the purpose of ascertaining the
extremes of variations which may occur, as, for instance,
during the night. It consists of two horizontal thermometers
attached to one frame, as in fig. 98 ; 6 is a mercurial ther-
Fig.98.
mometer, and measures the maximum temperature, by push-
ing forward, with the expansion of the column, a short piece
of steel wire, of such size as to move easily in the bore of
the tube ; it is left by the mercury at the remotest point
reached by the expansion ; a is a spirit-of-wine thermometer,
and measures the minimum temperature. It contains a short
cylinder of porcelain, shown in the figure, which retires with
the alcohol on the contraction of the column of fluid, but
does not advance on its expansion.
Name the three scales. What is boiling water in each ? What freez-
ing? Convert Centigrade 70° to Fahrenheit 112. What is the self-
registering thermometer ?
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78
HEAT.
113. The Differential Thermometer is a form of air-ther-
mometer, so named because it denotes only differences of
temperature. It consists of two bulbs
on one tube, bent twice at right angle%
and supported, as shown in fig. 99. A
little sulphuric acid, water, or other
fluid partly fills the stem only. When
the bulbs of this instrument are heated
or cooled alike, no change is seen in the
position of the column ; but the instant
any inequality of temperature exists
between them, as from the bringing the
hand near one of them, the column of
Fig. 99. fluid moves rapidly oyer the scale. A
modification of this instrument, of great delicacy, was con-
trived by Dr. Howard of Baltimore, in which sulphuric ether
was the fluid used, the bulbs being vacuous of air.
114. A Pyrometer is an instrument for measuring high
temperatures. As mercury boils at about 660°, we can
estimate the temperature of fused metals, and the like, only
by the expansion of solids. The only instrument of this
sort which we need mention, as it is the only one susceptible
of accuracy, is Daniell's Register Pyrometer. It consists of
a hollow case of black-lead, or plumbago, into which is
dropped a bar of platinum, secured to its place by a strap
of platinum and a wedge of porcelain. The whole is then
heated, as, for instance, by placing it in a pot of molten silver,
whose temperature we wish to
ascertain. The metal bar expands
pi cj ^^B much more than the case of black-
lead, and being confined from
moving in any but an upward
direction, drives forward the arm
of a lever, as shown in fig. 100,
over a graduated arc, on which
we read the degrees of Fahren-
heit's scale : (this graduation has
been determined beforehand with
great care.) This instrument
gives very accurate results; by
Fig. 100. it the melting point of cast iron
113. What the differential? 114. What are pyrometer*?
Darnell's.
Describe
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SPECIFIC HEAT. 79
baa been found to be 2786° R, and of silver 1860° F.
The highest heat of a good wind-furnace is probably not
much above 3300°. Fig. 88 (101) is a pyrometer of ordi-
nary construction.
115. Breguet* thermometer is constructed
upon the principle of the unequal expansion
of metals, (107.) A compound piece of me-
tal is formed by soldering together two equal
masses of silver and platina — two metals
whose expansion is very unequal. This is _
rolled thin and coiled into a spiral as shown K 101>
in a 6, (fig. 101.) It is suspended from a
fixed point p9 while its lower end is free and carries an
index t. Variations of temperature cause this spiral to un-
wind or wind up, and these motions are indicated by the
motion of the pointer. This is a more delicate thermometer
than any mercurial or spirit one. A beautiful modification
of Breguet's thermometer has been contrived by Mr. Saxton,
to measure the temperature of the sea in deep soundings.
116. All thermometers for accurate research are divided
on the glass stem by aid of a graduating engine and mi-
crometer j each instrument being, according to the plan of
Regnault, graduated by an arbitrary scale.
Capacity for Heat, or Specific Heat
117. Different bodies have different capacities for heat.
If equal measures of mercury and of water, for example,
are exposed to the same source of heat, the mercury will
reach a given temperature more than twice as soon as the
water, and it will cool again in half the time. Mercury is
said, therefore, to have only half the capacity for heat which
water has. We learn by trial that each substance in like
manner has its own relations to heat as respects capacity.
This is called also specific heat, a term synonymous with
capacity. Water is adopted as the standard of comparison
for this property, and the trial is usually made upon equal
weights rather than upon equal measures of the substances
compared. Specific heat connects itself curiously with the
atomic constitution of matter. Several modes may be em-
115. What is the metallic thermometer ? 116. How are thermometer!
accurately graduated ? 117. What is capacity for heat ? Give exaioploi.
What is specific heat?
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80
HEAT.
ployed to determine it; as by mixture, by melting, by
warming, or by cooling. The determination of this property
is called calorimetry, and the modes of experiment most
usual are either by mixture or by the fusion of ice.
118. The Method of Mixtures. — If a pint measure of
water, at 150°, be mixed quickly with an equal measure of
the same fluid at 50°, the two measures of fluid will have
the temperature of 100°, or the arithmetical mean of the
two temperatures before mixture. If, however, we rapidly
mingle a measure of water at 150°, and an equal measure
of mercury at 50, we shall find that they will have the tem-
perature of 118°. The mercury has gained 68°, and the
water lost about half as much, or only 32°. Hence we
infer that the same quantity of heat can raise the tempera-
ture of mercury through twice as many degrees as that of
water, and that the specific heat of water will be to that
of mercury as 1 : 047, when compared by measure. But
if we divide this number (0-47) by the density of mercury
(13*5) we obtain the number 0.035, which expresses the
specific heat by a comparison of weights. Water has then
more than 30 times the capacity for heat which is found in
mercury ; and in this peculiarity we find an important rea-
son of the singular fitness of this fluid metal for the con-
struction of thermometers.
119. By the melting of teem the calorimeter of Lavoisier,
is in fig. 102, the capacity of most substances for heat has
teen determined. A set of metallic vessels abc are so
arranged that when a warm body is
placed in c, all the heat it gives off in
cooling will go to melt the lumps of ice
surrounding it. The water of fusion
escapes at the cock *, and is measured
in the graduated glass beneath. To
cut off the heat of the surrounding air,
the space between a and b is also filled
with ice. The water which melts from
this portion is carried away by r. In
this apparatus the relative capacities
of all solid and fluid substances may,
with proper precautions, be accurately
Fig. 102.
What is calorimetry? 118. Describe the method of mixtures. 119.
What is Lavoisier's calorimeter ?
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CHANGES PRODUCED BY HEAP.
81
determined by the respective measures of water which flow
from s during the experiment, in which each body cools
from an agreed temperature, (e. g. 212°) to 32°, the constant
temperature of c. The same result may be reached in some
cases more simply by employing a large lump
of solid ice a (fig. 103) in which a weli W has
been scooped out, and covered by a lid of ice 6.
Any solid substance, or a fluid contained in a I
glass flask, may be placed in W, and, when the |
temperature has fallen to 32°, the water con- «. 10«
tained in W may be measured as before. To es- *s'
timate the capacity of heat in gases, atmospheric air it
chosen as unity — and the method of melting is adopted by
passing a certain volume of gas through a tube refrigerated
by ice.
120. It is plain, from what has been said, that the capar
city of bodies for heat is a phenomenon not indicated by
the thermometer. In the foregoing experiments, water and
mercury have been each heated to 212°, and yet the result
demonstrates that an equal weight of water contains at that
temperature about 30 times as much heat as the mercury.
The thermometer can indicate only actual intensity of heat,
and not its volume or quantity.
In the following table of specific heats, it will be seen
that this property has much connection with the physical
condition of bodies as respects fluidity or crystalline ar-
rangements, as is evident by comparing the capacity of
water and ice, and of the various forms of carbon : —
Water 1000
Ice 513
Turpentine 468
Carbon (charcoal) 241
Anthracite (Pa.) 201
Graphite... 201
Diamond 146
Btoel 116
Sulphur 177
Sulphur lately
fused 184
Ether 520
Alcohol 660
Mercury 33
Iron 114
Copper 95
Zinc 95
Brass 94
Silver 57
Antimony 51
Gold ; 32
Lead 31
Phosphorus 118
Glass W
Changes produced by Heat in the State of Bodies.
121. Fluidity is a result of temperature, as is seen in the
familiar case of water, which is either ice, water, or steam,
What simpler one is described ? 120. What docs the thermometer tail
in indicating? Give examples from table. 121. What is fluidity ?
6
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82 HEAT.
according to the temperature to which it is subjected. Many
solids can be melted by an increase of temperature, and the
melting point is always the same for a given solid. Some
substances pass at once to the fluid state, while others,
as wax, assume an intermediate pasty condition, and others,
like ice, fuse very slowly indeed. The degree of heat at
which bodies melt varies exceedingly. Thus platinum is
not melted at 3280°. Iron melts at about 2800° ; gold, at
2016°; silver, 1873° ; zinc, 773°; lead, 612°; tin, 442°;
Newton's alloy, 212°; potassium, 136° ; phosphorus, 108°;
wax, 142°; tallow, 92°; olive oil, 36°; ice, 32°; milk,
30°; wines, 20°; mercury, —39°; fluid ammonia, —46° ;
ether, — 47°; while pure alcohol is not solid at 175° below
Fahrenheit's zero.
122. Liquefaction is attended by a remarkable absorption
of heat. We have already seen that two equal measures of
water at different temperatures assume when mingled the
mean of their previous temperatures, (118.) If, however,
we take a pound of ice at 32°, and a pound of water at
212°, we shall find, when the ice is melted, that the two
pounds of water have the temperature of only 52° ; the ice
gains only 20°, while the water has lost 160°. There are,
then, 140° of heat lost in producing this change. We can
take another mode of trial. Let us expose a pound of ice
and a pound of water, each at 32°, to a constant source of
heat, in two vessels every way alike, and note the changes
of temperature by the thermometer. The same quantity
of heat is flowing into each vessel. When the ice is all
melted, we shall find that the water into which it is con-
verted has still only the temperature of 32°, while the other
pound of water has risen from 32° to 172° : here again we
see the loss of 140° of heat used in converting the ice into
water. We may reverse the last experiment, and take equal
weights of ice at 32° and water at 172° and mix them :
when the ice is all melted the mixture will still have the
temperature of only 32° ; so that, in whatever way we may
make the trial, we constantly observe the loss of 140° of
heat. This is called the heat of fluidity y it being necessary
to the existence of the water in a fluid state ; and it is also
designated latent heat, because it is lost, absorbed, or con-
Name the fluidity-points of several bodies. 122. What phenomenon
attends liquefaction? Give an example. How is this reversed? What
is latent heat ?
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CHANGES PRODUCED BY HEAT. 83
eealed, as it were, and no indication of it can be found by
the thermometer.
123. This law is equally illustrated by the slow freezing
of water. If a vessel filled with water at 52° be placed in
an atmosphere of 32°, it will rapidly cool down to 32° by
the losd of 20° of temperature. After this, it will, as may
be seen by the thermometer, remain at 32°, until it is all
converted to solid ice ; although we cannot doubt that it is
all the while giving out a quantity of heat, which had before
been insensible or latent. If the water had been ten
minutes in cooling from 52° to 32°, (or in losing 20°,)
then it would require one hour and ten minutes, or seven
times as long, for it to become completely frozen. If, then,
in equal times it lost equal degrees of heat, its latent heat
will be 20° X 7 = 140°, which is the same result as
before.
Thus we arrive at the seeming paradox that freezing is a
warming process. By experiment we may show that water
may be cooled some 8 or 9 degrees below its freezing point
and still remain liquid, if its surface be covered with a thin
film of oil, or if it is a thin smooth vessel, kept quite still ;
but the least disturbance will cause it, when in this situa-
tion, to become solid at once, and the temperature will im-
mediately rise from 23° or 24° to 32°. The freezing of a
part has therefore given out heat enough to raise the tem-
perature of the whole from 24° to 32°, or through 8°. Our
domestic experience in cold climates often supplies examples
of this fact. The solidification of a saturated solution of sul-
phate of soda is also an example of the same nature ; the ves-
sel containing the solution becomes sensibly warm. In like
manner, it is true that melting is a cooling process. A solid
can melt only by absorbing heat from surrounding bodies,
which must, of course, become cooler. Hence, in part, the
cooling influence of an iceberg, which is often felt for many
leagues, or of a large body of snow on a distant mountain ;
and the chill felt in the air on a bright day in spring, when
snow is rapidly melting on the ground.
It is a wise order of nature that makes the freezing and
thawing of snow and ice extremely slow and gradual pro-
123. Illustrate it by the freezing of water. How may water remain
Kquid below 32° ? How is freezing a warming process ? What proof
of design is here indicated?
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84 HEAT.
cesses. If -water became solid at once on reaching 32°, it
would be suddenly frozen to a great depth; and if ico
melted as quickly on reaching the same temperature, the
most sudden and dreadful floods would accompany these
events, and the common changes of the seasons would bo
calamitous to human comfort and life.
124. Freezing mixtures owe their powers, to the principles
just explained. Ice-cream is frozen by a mixture of snow
or pounded ice with common salt. In this case, the two
solids are rapidly changed to fluids ; the ice is melted by
the sal^ and the salt is dissolved by the water from the
melting ice. Both these operations absorb a large quantity
of heat. The surrounding bodies are called on to supply the
heat required, and the cream in a thin metallic vessel cools
so rapidly as to be soon turned to ice. The thermometer
will fall in this operation to 0° F. ; and this was the very
experiment by which Fahrenheit (111) assumed that he had
attained to a true zero of cold.
Nitrate of ammonia dissolved in water at 46° will sink the
temperature to zer"), and the exterior of the vessel becomes
at once thickly covered with hoar-frost. Common saltpetre,
(nitrate of potassa,) dissolved in water, lowers its tempera-
ture about 15° or IS0, and is therefore much used in the hot
regions of Asia, where it abounds, for cooling wine. Mer-
cury may be frozen by using a mixture of three parts of
chlorid of calcium and two of dry snow ; this mixture will
sink the temperature from -(-32 ° to — 50°. Five parts of
finely-powdered sal ammoniac and five of nitre, dissolved in
nineteen of water, will reduce the temperature from 50° to
10° ; and a little powdered sulphate of soda, drenched with
strong hydrochloric acid, will sink the thermometer from 50°
to 0°. But the most intense cold is that which results
from the volatilization of liquefied carbonic acid and nitrous
oxyd gases, by which the enormously low temperatures of
—175° and even 220° are reached.
125. Diminution of volume causes a portion of latent
heat to become sensible. Air suddenly compressed into a
small space, as in the fire-syringe, (fig. 104,) evolves heat
enough to fire a portion of dry punk on the end of the
piston. Metals rapidly struck, as on an anvil, become hot
124. What are freezing mixtures ? Give their theory. What if the
tort intense artificial cold ? 125* What ignites tinder in the fire-syringe t
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VAPORIZATION. 85
enough to enable the smith to light his fire. Wa-
ter poured on quicklime combines with it, with the
evolution of much heat; the water in this case
taking on the solid form. Sulphuric acid and
water, when mingled, give out great heat, and the
bulk of the mixture is less than that of the two
before mixing. Liquefaction is always a cooling
process, and solidification or condensation a heat-
ing one. A certain quantity of heat may be con- Fig. 104.
sidered as necessary to preserve each body in its
natural condition : if it be condensed, less is required, and
it gives out the excess ; and if expanded, it absorbs more.
Vaporization. — The Boiling Pbints of Bodies.
126. A continuance of the heat which melted the ice into
water, will turn the water into vapor or steam. The phe-
nomena which attend this physical change are not less curious
or instructive than the last.
If we place a known quantity of water over a steady source
of heat, we shall see the thermometer indicating each mo-
ment a higher temperature, until, at 212°, the fluid boils;
after which the thermometer indicates no further change,
but remains steady at the same point until all the water is
boiled away. Let us suppose that, at the commencement of
the experiment, the temperature of the water was 62°, and
that it boiled in six minutes after it was first exposed to the
heat : then the quantity of heat which entered into it each
minute was 25°, because 212°, the boiling point, less 62°,
leaves 150° of heat accumulated in six minutes, or 25° each
minute. Now if the source of heat continue uniform, we
shall find that in forty minutes all the water will be boiled
away; and hence there must have passed into the water, to
convert it into steam, 25° X 40 = 1000°. One thousand
degrees of heat, therefore, have been absorbed in the process,
and this constitutes the latent lieat of steam. So much heat,
indeed, was imparted to the water, that if it had been a fixed
solid, it would have been heated to redness; and yet the
steam from it, and the fluid itself, had during the whole time
a temperature of only 212°.
125. Give examples of beat evolved from condensation. 126. What is
Vaporization ? What is the latont heat of water ? How is it observed ?
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86 HEAT.
127. The capacity of water for heat is greater than thai
of any other body known; and in vapor it preserves the
same distinction. The latent heat of steam has been vari-
ously stated by different experimenters at 940°, 956°, 960°,
972°, and 1000°. The latest, and probably the most accurate
determination, is that of Brix, viz. 972°. The latent heat of
vapors has no relation to their points of boiling. The supe-
riority of vapor of water in respect to latent heat will be seen
by a comparison with that of several other bodies, viz. latent
heat of vapor of water = 972°, of ammonia 837°, of alcohol
386°, of ether 162°, of oil turpentine 133°. The large amount
of latent heat contained in steam becomes again sensible on
its condensation to water ; thus enabling us to make great
use of it as a means of conveying heat. The steam, so to
speak, takes up a large quantity of heat, and transports it
to the point where we wish it applied. One gallon of water
converted into steam, at the ordinary pressure of the atmo-
sphere, will raise five gallons and a half of ice-cold water
to the boiling point. In this way we can boil water in
wooden tanks, heat large buildings by steam-pipes, and make
numberless other useful applications of steam-heat in the arts.
It is found in practice that to heat buildings by steam, every
2000 feet of space to be heated to 75° requires one cubic
foot of boiler capacity, and that every square foot of radiat-
ing surface on the conducting pipes will heat 200 cubic feet
of space.
128. The boiling point of each fluid is constant, other
things being equal, but is peculiar to itself; thus, ether boils
at 96°, ammonia at 140°, alcohol at 173°, water at 212°,
nitric acid 250°, oil turpentine 314°, phosphorus 554°, sul-
phuric acid 620°, whale-oil 630°, and mercury at 662°.
129. Boiling is the mechanical agitation of a fluid by its
own vapor. This happens whenever the liquid becomes so
hot that its vapor can rise in bubbles to the surface, uncon-
demnned by atmospheric pressure or by the temperature of
the fluid. * The elasticity or tension of the vapor then bo-
comes greater than the united pressure of the fluid and the
air. When the boiling is vigorous, a great number of these
bubbles of uncondensed vapor rise to the surface at the same
127. What capacity has water for heat ? Give other latent beats. Why
♦he superiority of water for steam purposes ? 128. What of the boiling
points of fluids ? 129. What is boiling ?
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VAPORIZATION.
87
instant, and the liquid is thrown into violent agitation. If
a vessel containing cold water be heated suddenly, the lowei
surface receives the most heat ; bubbles of vapor are formed,
and rise a little way, when, meeting the colder water, the
vapor is at once condensed, and the liquid, before sustained
by the elastic vapor, falls with a blow on the bottom of the
vessel, often destroying it, if of glass.
130. The boiling point is much affected by the nature
and condition of the vessel. In a metallic vessel, water boils
at 210° and 211°. If a glass vessel be coated inside with shel-
lac, water boils in it at 211° ; but if it be thoroughly cleaned
with sulphuric acid, water in it may be heated to 221° or more,
without the escape of bubbles. A few grains of sand, a little
fragment of wire, or a small piece of charcoal will, however,
at once equalize these differences, and cause the water to
boil steadily at 212°. This simple means will prevent the
unpleasant jar from sudden escape of vapor, and frequent
fracture of the glass vessel. The boiling point is more re-
markably affected by variations in atmospheric pressure than
by any other cause, and we shall presently advert more in
detail to the phenomena connected with it.
131. Spheroidal State of Liquids. — If drops of water are
let fall on a metallic plate heated considerably above the
boiling point, it is observed that they do not
evaporate very rapidly, and that there is no hiss- T
ing sound, while the globules of water roll '
about quietly, floating, as it were, over the hot
surface. Thus situated, water is said to be in
the " spheroidal state/' a term employed by M.
Boutigny, who has made many curious and in-
structive experiments on this subject. Water
passes into this condition at 340°, and may at-
tain it even at 288°. A grain and a half of water
in this state at 392° requires 3*30 minutes to
evaporate; at a dull red-heat, the same quantity
will last 1 -13 minutes, and at a bright red, 0*50,
the rate of evaporation increasing with the tem-
perature. The water, in these experiments,
does not touch or wet the hot surface, but is-
kept at a sensible distance from it by the elas- **«• 105-
136. What affects the boiling point? 131. What is the spheroidal
state ? Describe the experiment in fig. 105.
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88
HEAT.
tic force of an atmosphere of its own vapor, as well also as
by the repulsive action of hot surfaces. The vapor is a
nonconductor, and its formation abstracts the sensible heat
from the fluid ; so that, notwithstanding the proximity of
the red-hot metal, the temperature of the fluid is found to be
always lower than its boiling point, being, for water, 205°-7;
for alcohol, 168° ; for ether, 93°-6 ; for hydrochloric ether,
50o<9, and for sulphurous acid 13°1. The temperature is
estimated as shown in fig. 105, where the liquid is contained
in a metallic capsule in the flame of a good eolipile.
132. If a thick and heavy silver capsule is heated to full
whiteness over the eolipile, it may by an
adroit movement be filled entirely with wa-
ter, and set upon a stand, some seconds
before the heat declines to the point when
contact can occur between the liquid and the
metal. When this happens, the water, be-
fore quiet, bursts into steam with almost
explosive violence, and is projected in all
directions, as shown in fig. 106.
On the principle explained, the hand may be bathed in a
vase of molten iron, or passed through a stream of melted
metal unharmed ; and we find here an explanation of the
success of some instances of magic.
133. The pressure of the atmosphere determines the boiling
point of fluids. It follows, therefore, that by a di-
minution of pressure, water may be made to boil
at a much lower temperature than 212°. If we
place some warm water in a glass under the air-
pump bell (fig. 107) and exhaust the air, the water
will boil vigorously, although the temperature, as
noted by the thermometer, is observed to fall con-
stantly. So, in ascending high mountains, the
boiling point falls with the elevation, from the diminished
pressure of the air. On this account, a difficulty is expe-
rienced at the hospice of Saint Bernard, on the Swiss Alps,
in cooking eggs and other viands in boiling water. This
place is 8400 feet above the sea, and water boils there at
196° : on the summit of Mount Blanc, it boils at 184°. Wc
Fig. 107.
132. Describe fig. 106. Why can the hand be safely plunged in fluid
iron ? 133. What determines the boiling point of fluids ? How is it o*
high mountains ?
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VAPORIZATION.
89
learn that it is the temperature, and not the boiling which
Serforms the cooking. The Rev. Dr. Wollaston proposed to
etermine the height of mountains by the boiling point. He
found an ascent of 530 feet to be equal to a decrease of 1°
in the boiling point ; and with a thermometer having large
spaces considerable accuracy may be attained. In deep pits
(as in mines) the boiling point rises.
134. The culinary paradox gives a very good illustration
of the phenomena of boiling under diminished pressure. A
small quantity of water is boiled in a glass vessel, as in the
figure : when the water is actively boiling, a good cork is
firmly inserted, and the vessel removed from the heat. It
may now be supported in an inverted position, with the
mouth under water, as seen in the figure. The boiling will
still continue, even more rapidly than before ; and if we at-
tempt to check it by affusion of cold water, we shall only
cause it to boil more vehemently. A little hot water will,
however, at once arrest the ebullition. In this case, the air
is driven out of the vessel on the first boiling of the water;
and, as we close the orifice while the steam is still issuing,
there is only the vapor of water in the cavity.
As this condenses from cooling, the pressure
on the water diminishes, and it boils more
easily from the heat it still contains: the affu-
sion of cold water, by producing a more per-
fect condensation, occasions a more violent
ebullition. Hot water, however, increases the
elasticity of the uncondensed vapor, and re-
presses the boiling. These alternations can
be produced as long as the water in the vessel
is warmer than the cold water poured on it.
When cold, the space. over the water will be a
good vacuum, and if we turn the water from
the ball into the neck, it will fall like a solid
body, with a smart blow and rattling sound.
This is sometimes called the ivater-hammer.
The perfection of the vacuum can be tested
by withdrawing the cork under water : the
pressure of the atmosphere will then drive in Flg' 108,
a quantity of water equal to the vacuum produced by the
first expulsion of the air.
134. What is the culinary paradox ? Explain the continued boiling.
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90 HEAT.
135. The Puhe Glass of Dr.
Franklin is a very good illustration,
p. im also, of boiling under diminished
lg' ' pressure ; and the cool sensation felt
by the hand at the instant when the fluid boils most violently,
is proof of the heat absorbed in converting a part of the
fluid into vapor.
Practical application of these facts is made in the arts on
a large scale, as in manufacturing sugar. The boiling of
the syrup is performed in vacuo, in large pans of copper,
holding 'several hundred gallons, the air and vapor being
removed from the vessels by the air-pump of a steam-engine :
the syrup is thus rapidly boiled down at a temperature of
150° to 180°, without any danger of burning. Vegetable
extracts are frequently made, and saline solutions boiled, in
the same way. Nothing in the arts shows more clearly the
value and beauty of scientific principles.
136. Ehvation of the Boiling Point by Pressure. — In
Papin's digester, (fig. 110,) a strong iron vessel with a safety-
valve, water may be heated under the pres-
sure of its own vapor to 400°, or higher.
This apparatus may be so arranged with a
thermometer and pressure gauge, (fig. Ill,)
that we can note the relations of pressure and
temperature (Marcet's apparatus) : the ther-
mometer-ball is in the steam cavity; the
gauge descends into some mercury in the
bottom. It is supported by a tripod / over
a lamp e, and a stopcock d cuts off the ex-
Fig. 110. ternal air, when the boiling has commenced.
As the steam accumulates, it, pressing on the mercury, forces
it up the tube, against the imprisoned air in the gauge b.
When the gauge shows double the pressure of the air, the
thermometer will indicate a temperature of 250°*5. 3 at-
mospheres of pressure raise the temperature to 275°, 4 to
293°-7, 5 to 307°, 10 to 358°, 15 to 392°-5, 20 to 418°-5,
25 to 439°, 30 to 457°, 40 to 486°, and 50 atmospheres
raise it to 510^. Perkins heated steam so highly that a
jet of it set fire to combustible bodies.
135. Explain the pulse-glass. What practical application is made of
these principles? 136. What is Papin's digester? What Marcet's?
What relation is there between boiling points and pressure ?
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VAPORIZATION.
91
The clastic power of steam in con-
tact with water is limited only by
the strength of the containing ves-
sel ; bat if steam alone be heated
without water, then its elastic or
expansive power is exactly like that
of other gases or vapors. M. de la
Tour has shown that many liquids
may be entirely converted into va-
por in a space but little greater than
their own volume.
137. The increase of volume in
changing from a liquid to a gaseous
state is such, that 1 cubic foot of
water becomes nearly 1700 cubic
feet of steam; or, in whole num-
bers, a cubic inch of water becomes
nearly a cubic foot of steam ; while
1 cubic foot of alcohol and ether
yield respectively 493 and 212 cubic
feet of vapor. The latent heat of
steam diminishes as the sensible
heat rises, so that the heating power
of steam at 400° is no greater than
that of an equal volume at 212°.
On the other hand, the latent heat
of steam produced at low tempera-
tures, as in a partial vacuum, in-
creases as the sensible heat falls.
Hence there is no fuel saved by dis-
tilling in vacuo. There is a con-
stant ratio between the latent and
sensible heat of steam ; the two added together always give
the same sum. Thus, steam at 212° has latent heat = 972°;
giving the sum 1184°. Subtract the sensible heat of steam
at any temperature from the constant number 1184, and we
have the latent heat for that temperature, e. g. steam at
280° has a latent heat of 904°. So, also, at 100°, steam
has 1084° of latent heat.
138. Equal volumes of different vapors contain equal quan-
tities of latent heat. By weight, water vapor has about twice
Fig. ill.
What was De la Tour's observation? 137. What is the dilatation of
■team ? What relation between oensihlo and latent heat ?
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92
HEAT.
Fig. 112.
and a half more latent heat than alcohol vapor, (972 : 885;)
but tho specific gravity of alcohol vapor is about 2*5 times
*L greater than that of water-vapor, (1590 : 622.)
1 Consequently, if the same expenditure of heat
I produces from all vapors the same bulk of
II vapor having equal quantities of latent heat,
J-i there can be no advantage in substituting any
^^ other fluid for water as a source of vapor in
the steam-engine.
139. The Steam-Engine. — The principle
of this apparatus is simple, and easily illus-
trated by the little instrument contrived by
Dr. Wollaston, (fig. 112.) A glass tube, with
a bulb to hold a little water, is fitted with a
piston. A hole passes from the under side
through the rod, and is closed by a screw at a.
This screw is loosened to admit the escape of
J the air, and the water is boiled
over a lamp : as soon as the steam
issues freely from the open end of
the rod, the screw is tightened,
and the pressure of the steam then
raises the piston to the top of the
tube ; the experimenter withdraws
it from the lamp, the steam is
condensed, and the air pressing
freely on the top of the piston
forces it down again; when the
operation may be repeated by again
bringing it over the lamp.
In the common condensing en-
gine (fig. 113) a cylinder a is
fitted with a solid piston, the rod
of which moves through a tight
*~l packing in the cover, and to it the
machinery is attached. A pipe
d brings the steam from a boiler
to the valve arrangement c by
which the steam is admitted, alter-
nately, to the top and bottom of
Fig. 113.
138. What of equal volumes of different vapors ? Compare alcohol
and water. 139. What is Wollaston's toy? Give the principle of thf
Bteam-cngine in fig. 112.
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VAPORIZATION.
93
the cylinder ; and also an alternate communication is opened
with the condenser b. Thus, when the steam enters at the
top, (in the direction of the arrow,) that at the bottom of
the piston is driven through the lower opening to b, where
it is condensed. The valves are moved at the proper time
by the machinery.
140. Evaporation from the surface of liquids takes place
at all temperatures. Even snow and ice waste by evapora
tion, at temperatures much below 32°. Mercury rises in
vapor even at the temperature of 60°. Faraday found at
that temperature that a slip of gold-leaf suspended in a
vacuum over mercury was, in a few hours, whitened by amal-
gamation with the vapor of that metal. The state of the
atmosphere as to dryness and pressure influences
natural evaporation, which is greatly increased by
heat and a rapid wind. It must be remembered
that all the water which falls to the earth in snow
and rain has arisen in evaporation. That natural
evaporation takes place only from the surface is
proved, by its being entirely prevented by. a film
of oil on the fluid.
141. Influence of Pressure on Evaporation. — If
we introduce a few drops of water into the vacuum
above the mercury in a barometer tube, a part of
it will be vaporized, and the level of the mer-
cury will be correspondingly reduced. The tension
of the vapor is increased by an elevation of tem-
perature. A larger tube may be placed over the
barometer tube, the lower end of which dips under
the mercury, and we may then fill the intervening
space with hot water, ffig. 114.) The vapor of
the confined water will force down the column of
mercury in direct proportion to the temperature ;
and, by means of a thermometer and a scale of
inches, we can tell exactly the tension of the vapor
of water for every temperature under 212°.
142. Maximum Density of Vapors. — Into the
torricellian vacuum introduce a portion of sulphuric
ether: a part of it is instantly converted into
vapor, and the mercury depressed thereby to lfr
140. What of natural evaporation? 141. What influence has present*
on evaporation?
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94
HEAT.
about 14 inches. If we have a deep cistern, as in fig. 115,
in which we can depress the tube by the pressure of the
hand, it will be seen that the film of liquid
I on the surface of the mercury increases as the
tube descends, until the vapor of ether is
at last entirely converted to the fluid state.
On withdrawing the hand, the ether again
flashes into vapor. There is then, it is plain,
a point of density (or pressure) for the vapor
of ether, which cannot be passed without again
converting it to a liquid. This is true of all
volatile liquids ; and this point is called the
maximum density of vapors. The weight
of 100 cubic inches of water vapor at 212° is
14*962 grains, while, at 32°, the same volume
of vapor of water is only 0-136. The point
of maximum density of a vapor is lowered by
cold as well as by pressure, and when these
two effects are united, we can convert many
gases, which are quite permanent at the com-
mon pressure and temperature of the air, into
liquids, and even to solids.
143. The cold produced by evaporation is
owing to the assumption of heat by the newly
formed vapor. Availing ourselves of this prin-
ciple, water may be frozen by the evaporation
of ether, even in the open air. Leslie showed
that water might be frozen by its own evapo-
ration, as in the experiment figured in the mar-
gin, (fig. 116.) Water is contained in a shal-
low capsule supported by a tripod of wire
over a dish containing sulphuric acid, and
the whole is covered by a low air-jar. On
working the pump, the water eva-
porates so rapidly in the vacuum
as to boil even at 72° : its vapor
is instantly absorbed by the sul-
phuric acid, and in this way both
Fig. 116. the sensible and latent heat are
removed so rapidly that the water is frozen, while still ap-
parently boiling.
142. What is meant by maximum donsity of vapors ? 143. Whence
the cold of evaporation '( What is Leslie's experiment?
Fig. 115.
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VAPORIZATION. 96
The Cryophorus, or frost-bearer, offers another illustration
of the same principles. This instrument, invented by Dr.
Wollaston, consists of two glass bulbs blown upon the same
tube(fig.H7):
one of them
contains a lit-
tle water; the
space over the
water is a va- Fi£- lir*
cuum, the tube having been sealed when the water was
boiling. On placing the empty bulb in a freezing mix-
ture, the vapor of water is so rapidly condensed as to freeze
the fluid in the ball which is remote from the freezing
mixture, and which is usually protected by an envelope of
muslin.
144. Dew- Point — If we drop bits of ice into a tumbler
of water (one of polished silver is best) having the same
temperature with the air, and watch the fall of a thermo-
meter placed in it, we can denote with accuracy the temper-
ature of the water, when it has cooled so far that moisture
begins to be deposited on the clean surface of the glass.
This temperature is called the dew-point ; and the number
of degrees between it and the temperature of the air is an
accurate indication of the actual dryness of the air. In
this climate, in summer, this difference amounts often to
40° or more, and in India it has been known to be as much
as 61° ; that is, with an external temperature of 90°, the
dew-point has been seen as low as 29°. The amount of
moisture in the air has an influence on the indications of
the barometer, and it is always requisite, in making baro-
metrical observations, to make a correction for the tension
of the vapor of water in the air.
Several common facts are explained by a reference to these
principles. When the air is highly charged with humidity,
it deposits dew on any substance colder than itself. A glass
of iced water in summer is immediately covered with a coat of
condensed vapor ; when a warm humid morning succeeds a
cool night, we see the pavements and walls of the houses
reeking with deposited water, as if they had been drenched
with rain. The fall of dew (as has been already explained)
Describe the cry ophorus. 144. What is the dew-point? Howobserred?
What common facts are explained by it ?
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^Googk
%
HEAT.
occurs in consequence of the radiation from the earth re*
ducing its temperature below the " dew-point."
145. Hygrometers are instruments to determine the
amount of moisture in the air. One much used is called
the wet bulb hygrometer, (fig. 118,) or psych ro-
meter, and consists of two similar delicate mer-
curial thermometers, the bulb of one of which is
covered with muslin and is kept constantly wet
by water, led on to it by a string from a tube in
the centre. The evaporation of the water from
the wet bulb reduces the temperature of that
thermometer to which it is attached, in propor-
tion to the dryness of the air, and consequent
rapidity of evaporation. The other thermometer
indicates the actual temperature ; and the differ-
ence being noted, a mathematical formula ena-
bles us to determine the dew-point.
146. But a much more delicate instrument for
this use is that of Mr. Daniell, which is con-
structed on the principle of the cryophorus, (143.)
It is represented in fig. 119. The long limb
ends in a bulb, which is made of black glass,* that
Fig. 118. the condensed vapor may be more easily seen
•n it. It contains a portion of ether, into which dips the
flail of a small and delicate thermometer contained in the
cavity of the tube. The whole instrument contains only
the vapor of ether, air having been removed. The short
limb carries an empty bulb, which is
covered with muslin. On the support is
I another thermometer, by which we can
observe the temperature of the air. When
an observation is to be made by this in-
strument, a little ether is poured on the
muslin : this evaporates rapidly, and of
course reduces the temperature of the
other ball. As soon as this has fallen
to the dew-point, the moisture collects
and is easily seen on the black glass.
At this instant, the temperature indicated
Fig. 119. by the two thermometers is noted, and
145. What are hygrometers ? Describe the wt?t bulb. 146. Describe
Darnell's. What is the principle of Daniell's? Which is the best'
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VAPORIZATION.
97
to* difference gives us the true dew-point. The latest and
most improved form of hygrometer is that of Regnault: it
involves the principle of DanielPs, with important means of
additional accuracy.
147. Diffusion and Effusion of Gases and Vapors. — The
vapor of water will rise and fill a confined vessel of air, and
have the same tension as if no air were present. It will
take a longer time to do it, but as much will ultimately rise
as if the space were a vacuum. The air seems to be an
impediment only to the rapid rise of the vapor. On the
same principle, probably, is explained the curious &
and important fact, that, when different gases are
in contact, they will not remain separate, but will
soon mingle uniformly, even against the force of
gravity. Our atmosphere, for instance, is composed
of two gases, the specific gravities of which are as
976 to 1130, and we might suppose that the heavier
would be at the bottom, as would be the case in two
such liquids as water and oil. But they are found
to be in a state of uniform mixture. If we connect
together by a narrow tube two bottles, (fig. 120,)
containing, one a light gas, hydrogen, and the other
a heavier gas, oxygen, and place the heavy one
uppermost, in a few hours we shall find them per-
fectly commingled ; as may be proved by the fact
that the mixture will explode violently on touching Fi«- 12°*
a match to the open mouth of one of the vessels,
which we know a mixture of these two gases
will always do.
148. If we fill the end of a glass tube
(fig. 121) of moderate size with a plug of
plaster of Paris, we form what is called
Graham's diffusion tube. When the plaster
is dry j if the tube be filled, for example,
with hydrogen gas, and its open end intro-
duced into a vessel of water, this liquid is
seen to rise rapidly, owing to the escape of
the light gas into the air. At the same time
the air enters the tube, and renders the mix-
ture explosive ; but nearly four volumes of Fig. 121.
147. What is meant by diffusion of gases ? Give an ilfcrctration. 14S.
iVhat is the diffusion tube ? In what proportion does the air enter?
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98 HEAT.
hydrogen escape for one of air which enters, and these are
called the diffusion volumes of hydrogen and air. Every
gas has its own diffusion volume depending on its density,
these being inversely as the square root of the densities of
the gases. The same law pertains to the rapidity with which
gases rush into a vacuum through a minute orifice.
149. The passage of gases through moist membranes is
connected with this subject, but involves also another con-
dition, viz. the solubility of certain gases in water. For
example, a bladder partly full of air, and tied tightly at the
neck, is introduced into an air-jar full of carbonic acid;
after some hours the bladder is found much distended, and
may finally burst, from the passage of the carbonic acid gas
into it. This is effected by the solubility of this gas in
water : it thus passes the pores of the membrane, and is
rapidly diffused again in the air of the bladder. Dr. Mitchell
found that the time required to pass the same volume of
several gases through the same membrane was 1 minute
for ammonia, 2 J minutes for sulphuretted hydrogen, 3} for
cyanogen, 5 J for carbonic acid, 6} for nitrous acid, 28 for
olefiant gas, 37 J for hydrogen, 113 for oxygen, and 160 for
carbonic oxyd. For nitrogen the time was much greater.
150. Liquefaction and Solidification of Gases. — In 1823,
Faraday first demonstrated the possibility, by united cold
and pressure, of reducing several gases to the liquid and
even solid state. The apparatus originally employed in
these interesting but hazardous experiments, was simply a
stout glass tube, bent as
in figure 122, containing
the materials to evolvo
the gas, and heated at
» both ends. If cyanogen
Fig. 122. is to be liquefied, dry
cyanid of mercury is placed in one end of the tube, and
heated, while the empty end is cooled in a freezing mixture :
the cas, accumulating in a narrow space, is liquefied by
the force of its own elasticity. Some hazard attends these
experiments, and the operator should be protected by gloves
and a mask of wire-gauze. In this way, chlorine, cyanogen,
What is the law of diffusion? 149. What of the passage of gasoi
through membranes ? Give an example. What are Mitchell's results t
150 Who first liquefied gases ? What was tho means?
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VAPORIZATION.
99
carbonic acid, nitrous oxyd, and several other gases have
seen reduced to the liquid state, and some to the solid con*
dition. Several of these gases — as ammonia, cyanogen, and
sulphurous acid — may be liquefied by cold alone, without
additional pressure.
151. M. Thilorier's apparatus for liquefaction of carbonic
acid involves the same principle. In fig. 123, g is the gene-
rator of the gas, a strong cast-
iron vessel, hung by centres on
a frame /; in it is put the
requisite quantity of carbonate
of soda and water, and a tube a
of copper, holding an equivalent
amount of strong sulphuric acid ;
the cap of red metal is strongly
screwed in, the valve closed,
and the position of the appa-
ratus inverted, by turning it
over on its centres; the acid
then runs out among the car-
bonate of soda, and an enor- J
mous pressure is generated by Fi 123
the successive portions of gas
evolved. After a time, when the action is complete, the
generator is connected by a metallic tube with the receiver
r; stopcocks, simple screw-plugs having a conical point,
confine the gas, and being opened, the liquefied gas collects
in r, which is cooled by a freezing mixture for the purpose
of condensing it. In this way, several successive quarts of
.the liquid carbonic acid gas are accumulated in r. A por-
tion of this liquid may be safely drawn off into a strong
glass tube refrigerated. It can then be drawn off by a jet
j secured to the top, which enters a metallic box b with
perforated wooden handles. The rapid evaporation of a
part of the liquid gas absorbs so much heat from the rest,
that a considerable portion is converted to a fine white solid,
like dry snow, which fills the box. When once solidified,
it wastes away very slowly, and may be handled and
moulded with ease. If suffered to rest on the hand, how-
ever, it destroys the vitality of the flesh, like a hot iron.
It is now in a condition analogous to bodies in the spheroidal
What gases have been liquefied ? Describe Thilorier's apparatus.
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100 ELECTRICITY.
state (181 ;) being surrounded by an atmosphere of its owa
vapor, the radiation of heat to it from surrounding bodies is
cut off, and it acquires the very low temperature of — 140°.
If it is wet with ether in a capsule containing mercury, th*
latter is frozen solid, and can ; then be hammered with a
wooden mallet, and drawn out like lead. When moistened
with ether in vacuo, with certain precautions, the very low
temperature of — 166° is produced. Carbonic acid at 0° has
a tension of nearly 23 atmospheres ; at 32° its tension is
38 J atmospheres; at —84°, 12}; at —75°, 4.60; and at
— 111°, 1-14 atmospheres. It becomes at — 71° a clear
transparent solid, sinking in the surrounding fluid.
This apparatus once exploded in Paris, killing the assist-
ant in a frightful manner. l It is, however, due to Mr.
Chamberlain, of Boston, to say that the author has re-
peatedly used several of these instruments of his construc-
tion with entire safety.
152. By the use of mechanical pressure, and the enor-
mously low temperature of the bath of carbonic acid and
ether in vacuo, Faraday has succeeded in reducing several
other gases to the liquid or solid state. These facts will be
mentioned under the history of the several substances.
The greatest artificial cold hitherto observed is 220° below
zero of Fahrenheit, and was obtained by Natterer, with the
aid of a bath of liquid nitrous oxyd and sulphuret of carbon
in vacuo. The greatest natural cold recorded is — 76° below
zero.
Several gases have resisted all attempts to reduce them to
a liquid state, viz. hydrogen at 27 atmospheres; oxygen at
58} ; nitrogen, nitric oxyd, and carbonic oxyd at 50, and coal
gas at 32 atmospheres, aided by the greatest artificial cold.
IV. ELECTRICITY.
153. More than 600 years b. c. the ancients observed in
amber a remarkable power of excitation by friction. Mo-
dern science has conferred on this power the name of elec-
tricity, from the Greek word for amber, (electron.) This
force, or power, has various modes of existence or manifesta-
152. How has Faraday reduced other gases? What is the lowest
temperature observed? What in nature? What gases hay© resisted
liquefaction? 153. What was the first electrical observation?
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MAGNETIC ELECTRICITY. 101
tion, which are chiefly, 1. Magnetic electricity; 2. Fric-
tional, or statical electricity; 3. Dynamical, voltaic, or gal-
vanic electricity, (from chemical action ;) 4. Thermo-elec-
tricity; and, 5. Animal electricity.
Magnetic Electricity, or Magnetism,
154. Lode-stone, — A kind of iron-ore has heen knowi
from remote antiquity, that has the property of attractiir,
to itself small particles of iron; this is called
the lode-stone. By contact, it can impart its
virtues to iron and steel, and also, to a consider-
able degree, to cobalt and nickel. As it
abounded in Magnesia, it wfe called by Pliny
rnagnes, and hence the name magnet This ore
mounted in a frame of soft iron 11, (fig. 124,) f{ ^124
constituted the original magnet : pyf are the
poles. A bar, or needle of steel, which has received the
magnetic influence, when suspended on a point,
will be found to have a directive tendency,
by which one end turns invariably to the
north. The needle, therefore, has polarity,
and the end turning north is called the north
pole, and the other end the south pole.
155. Polarity. — If we bring the north end
of a magnetic bar near to the similar end of g* 125#
the suspended needle, the latter will move away, as indi-
cated by the arrows, being repelled by the similar power of
the bar. If, however, we bring the end N - -.^...^a
toward the opposite end of the needle S, it IP ^' — IW
will be attracted to the bar, and strive to move Flg* 126#
as near to it as possible. The reverse is, of course, true of
the opposite end of the bar. If, in place of a magnetic bar,
we had used a bar of unmagnetic iron, we should have found
both ends of the suspended needle equally, but less power-
fully, attracted by it. We thus learn (1) that the magnet
has polarity ; and (2) that poles of the same name repel,
and those of opposite names attract each other.
156. Induction of Magnetism. — The manner in which a
magnet, or lode-stone, imparts its own power to surrounding
What modes of electricity are named? 154. What is the lode-stone ?
What is the needle? 155. What is polarity? What is the law of r*.
pulsion? 156. What is induction ?
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\
It)2 ELECTRICITY.
i«l substances, is called induction , and those
bodies capable of manifesting this power
are said to be magnetized by the tn-
ductive influence. Thus, a series of
bars of soft iron laid about a magnetic
bar, as in the figure, will all become
temporarily magnetic by induction ; and
in obedience to the law just stated,
their ends next the N are all S, and
their remote ends all N. Every mag-
Fig. 127. ne^ g0 to gpea]^ js surrounded by an
atmosphere of influence, which has its centre in the poles
of the magnet, and diminishes in intensity inversely as the
square of the distance. This decrease of force is
prettily illustrated by an experiment shown in the
annexed cut. The bar magnet holds a large key ;
this can hold a second smaller than itself; this, a
nail ; the nail, a tack-nail \ and lastly, a few iron-
filings are held by the tack-nail; and the whole re-
ceive their magnetism by induction from the bar,
and each article has its own separate polarity. In-
duction takes place through a glass-plate, or any
similar substance.
157. Permanent magnets can be made only of
hardened steel. Soft iron and steel become mag-
nets only while under the influence of other magnets,
and lose their own power as soon as removed from
them. Magnetism is imparted by ' touch,9 as it is
technically called, from a previously existing mag-
net. An unmagnetic bar of hardened steel, when
properly rubbed by the poles of a magnet, will itself
soon acquire polarity and magnetic power. Mag-
Fig. 128. netism is thought to rest mostly on the surface of
the metal. Every magnet is regarded as made up of a
great number of small magnets, so to speak, each particle
of steel having its own polarity. We cannot conceive of one
n«n«n«n«n«n«n« »« sort of polarity existing
N » E5 S5 F™ T9* ^^ r™ '-JB* S w^^out tne ofcher. Thus,
c5c3l§E!^!i5il5ciisEH in figure 129, we see a
Fi 129# magnified representation
Explain figs. 127 and 128. 157. What aro permanent magnets ? What
U attraction and ' touch' ? How are the forces in a magnet distributed ?
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MAGNETIC ELECTRICITY. 103
of this condition. Each little magnet has its own n and s.
Those which occupy the middle of the bar, being acted on
alike in all directions, can show no power ; but the force
accumulates toward each end, until we find the greatest
power in the last range of particles, which we term the
poles.
If we dip a magnetic bar in iron-filings, we shall find only
the ends attracting a tuft of the metallic particles, while the
middle is free. If two magnetic bars, however, like the
figure, are placed together, (-{- and — ,) and a sheet of
paper laid over them, they will attract iron-filings scattered
on the paper, in the way .ysff^\iTiu^--''^i^^Wl1/^y-
here a pair of central poles ^1:^E!»mb!Z3^^^__^^B^^
part of the simple bar had Fig. 130.
not. The particles of iron arrange themselves in what are
called magnetic curves. These curves represent very nearly
the lines of magnetic force which always environ a magnet,
and tend to impart magnetic properties to all bodies — solid,
liquid, or gaseous — which come within their range.
158. Artificial Magnets are made of all forms, the most
common being the so-called horse-shoe magnet, shaped like
figure 131. It is found that the power of magnets ■ ■
is much increased by uniting several thin plates of W
hardened steel, each of which is separately magnet- FiS« 131»
ized. A bar of soft iron, called the keeper, is placed across
the poles of the horse-shoe magnet, to prevent it from losing
power; and if it be made to hold a weight nearly equal to
the power of the magnet, it will be found to gain strength daily
up to a certain point, and in like manner to lose its magnet-
ism if unemployed. Artificial magnets, weighing one pound,
have been made to sustain 28 times their own weight.
159. The Earth'* Magnetism. — The earth is regarded as
a great magnet. Its power is equal, according to Gauss, to
that which would be conferred if every cubic yard of it con-
tained six one-pound magnets. The sum of the force is
equal to 8,464,000,000,000,000,000,000 such magnets.
The magnetism which we see in bars of steel and the lode-
Dlustrate this as in fig. 129. 158. How are magnets formed and pre-
served ? What is terrestrial magnetism ? What its foroe in a cubic yard f
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104 ELECTRICITY.
ftone is the result of induction from tbe earth. Magnetism
from the earth is induced in all bars of steel or iron which
stand long in a vertical position. Tongs and blacksmiths'
tools are often found to be magnetized. A bar of iron held
in the magnetic meridian, and at the proper inclination,
becomes immediately magnetic from the induction of the
earth ; and the effect may be hastened by striking it on the
end with a hammer : the vibration seems to aid in inducing
the magnetic force. The tools used in boring and cutting
iron are also generally found to be magnets. The magnetic
poles of the earth are not in the same points with the poles
of revolution or the axis of the earth, and for this reason
the magnetic needle does not point to the true north and
south, but varies from it more or less, and differs at different
times, as the magnetic pole alters its position. This is
called the variation of the needle.
160. Dipping Needle. — The magnetism of the earth is
beautifully shown by the dipping needle, represented in the
annexed figure. The needle n is sus-
pended on the horizontal bar a, so as
to move in a vertical plane, instead of
horizontally, as in the compass-needle.
The graduated vertical circle c is placed
in the magnetic meridian, and the needle
then assumes, in this latitude, (41° 18',)
D the position shown in the figure, dipping
Fig. 132. at an angle of 73° 27'. Over the mag-
netic equator it would stand horizontal, being equally at-
tracted in both directions. At either magnetic pole it would
be vertical. The horizontal variation of the needle, its dip,
and the intensity of the polar attraction, are subject to daily
and local changes, from the fluctuations of temperature in-
fluencing the magnetic conditions of the atmosphere, as
shown by the late results of Faraday.
161. Magnetics and Diamagnetics. — Dr. Faraday, in 1845,
made the important discovery that all solid and liquid sub-
stances, and many gases, were subject to the magnetic in-
fluence. According to his results, confirmed by numerous
subsequent observers, all bodies may be subdivided into two
great classes — the magnetic and diamagnetic. To the first
How are objects affected by it? Where are the magnetic poles ? 160.
What is the dipping needle ? What is said of variations in dip, <kc ?
Digitized
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ELECTRICITY OP FRICTION. 105
class belong all bodies which act like iron and nickel — that
18, which place themselves, when suspended as a needle,
axiaUy or in the line connecting the poles of a magnet —
and which also exhibit the familiar mode of attraction by
either pole of a magnet alike. The bodies belonging to this
class are either metals or oxyds and salts of metals, (both
solid and liquid.) To the second class belong all liquids
and solids which do not belong to the magnetic class. Bis-
muth appears to be the most remarkable substance in
diamagnetic energy. A suspended needle of this metal
places itself at right angles to that position which iron
assumes under the same circumstances. A few bodies of
each class are enumerated in the following list, where we
observe that iron and bismuth are at the extremes, each
standing as the type of its own class, while air and vacuum
occupy the zero, or neutral point of quiescent inactivity : —
Iron, nickel, cobalt, manganese, palladium, crown-glass,
platinum, osmium, — 0°, air and vacuum, arsenic, ether,
alcohol, gold, water, mercury, flint-glass, tin, heavy glass,
antimony, phosphorus, bismuth. It is a curious sight to see
a piece of wood, or of beef, or an apple, or a bottle of water,
repelled by a magnet; or, taking the leaf of a tree and
hanging it up between the poles, to observe it take an
equatorial position.
162. The latest results of Faraday show that oxygen gas
is to be reckoned as a magnetic, having about 3J5th part the
capacity of iron for magnetic induction. This fact connects
itself in the most important manner with the magnetic con-
dition of the atmosphere — the daily variations in dip and
intensity — as probably also with the aurora borealis.
Electricity of Friction, or Statical Electricity.
163. Statical electricity is evolved by several of the same
causes which we have named as sources of heat. Friction
excites it abundantly ; chemical action still more so. It
attends animal life, and is powerfully exhibited in some
animals, as in the torpedo and electrical eel : heat evolves
it, as in the mineral tourmalin; and we have reason to
161. What axe magnetics and diamagnetics? Name some of them. 162.
What is Faraday's discovery regarding oxygen ? 163. What are sources
of (fictional electricity ?
Digitized
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106 ELECTRICITY.
believe that the sun's rays are perpetually exciting electric*,
currents in the earth. Like heat, it neither adds to nor sub*
tracts from the weight of matter ; but, unlike heat, it pro-
duces no change in dimensions, and does not affect the power
of cohesion in bodies. In powerful discharges, however, it-
overcomes cohesion by rending or fusion. All matter is
subject to its influence, and it can be transferred from an
excited body to one previously in a neutral state.
We shall treat this curious and most interesting subject
very briefly, as its chemical relations are much more limited
than those of galvanism.
^^ 164. Electrical Excitement — If we briskly
-JV,\.. rub a glass tube with warm and dry silk, and
" bring it near to any light substance, as some
Pie 133 P*fcD> 0D ^e te^e> (fifr 1^>) a fl00^ °^ cot"
ton, some shreds or silk, or, as in fig. 134,
to two balls of pith suspended on a hook by delicate wire,
the light substances will at first be strongly attracted to the
tube, but in an instant will fly from it, as if
I repelled by some unseen force ; and any further
ft effort to attract them to the excited glass will
/ \\ only cause their continued removal. Each se-
/ \ \, parate thread of silk and each pith -ball seems
O <X & to retreat as far as possible from the glass tube
Fie. 134. an(* fr°m *te feN°ws* W> *n *ne P*ace °* tne
glass tube, we use a stick of sealing-wax rubbed
with dry flannel, and present this to the light substances
which have been excited by the glass tube, we shall find a
very strong attraction manifested between them : the light
substance previously excited by the glass will move to the
excited resin much more actively than a substance not pre-
viously excited in this way ; and two substances separately
excited, one by the glass and the other by the resin, will
attract each other with equal power. The first of these is
called vitreous, and the second resinous electricity. These
simple phenomena form the basis of all electrical science.
165. Electrical Polarity. — There is a strong analogy be-
tween the two sorts of electrical excitement and the opposite
powers of the magnet. The vitreous is to the resinous elec-
What similarity has it to heat? What differences ? 164. How do you
excite a glass tube ? How does it affect pith-balls, Ac. ? How if wax \*
l*d ? 165. What is electrical polarity ?
Digitized
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ELECTRICITY OP FRICTION.
107
Q -Q+ 0+^i-.^4-
tricity as the north
pole of a magnet is
to the south. Hence
we call the vitreous
the positive electri- Fig. 135.
city, and the resinous the negative electricity. A row of pith •
balls, (fig. 135,) when excited by induction, or influence, stand
related to each other as shown by the signs plus and minus.
166. Electrical machines are constructed for the easy ex-
citation of large quantities of electricity. Two forms of
this machine — the cylinder
and the plate — are in com-
mon use. In the plate ma-
chine, (fig. 136,) ci is a
wheel or plate-glass, turned
on an axis by a handle m.
The electricity is excited by
the friction of two cushions
or rubbers pressing against
the plate, and covered with
a soft amalgam of mercury,
tin, and zinc, which greatly
heightens the effect. The
rubbers are connected with the earth by a metallic chain.
The excited glass delivers its electricity to several sharp
points of wire attached to the bright brass arms it, and
connected with the great conductors fg. The conductors
are perfectly insulated by glass supports h h.
In the cylinder machine, (fig. 137,) a hollow cylinder of
glass v is used, to excite the electricity ; c is the rubber,
and a r are the prime
conductors. When*
the winch is turned, JL^
bright sparks of a*
violet color, form-
ing zigzag lines like
lightning, dart with
a sharp sound to any
conducting substance
brought near to the
Fig. 13d.
Fig. 137,
How is it like magnetic ? 166. What is the plate machine ? What th»
cylinder ? Describe figs. 136 and 137.
Digitized
byGoogk
108
ELECTRICITY.
great conductors. This is positive electricity. If negative
electricity be wanted, we must insulate the rubbers, and,
sonnecting the opposite conductor with the earth, draw the
sparks from the rubber. For this purpose, the construction
in fig. 137 is most convenient. Every care must be taken,
in the use of an electrical apparatus, to keep it
clean and smooth, and particularly free from moist-
ure. Warm flannel or silk is to be used to wipe the
surface.
167. Electroscopes, or Electrometers. — The quad-
rant electroscope (fig. 138) is usually attached to the
prime conductor, to indicate the activity of the ma-
chine by the more or less elevated angle assumed
by the arm. The pith-balls of fig. 135 answer the
Fig. 138. same purpose, and may also denote the kind of excite-
ment. For example, if they are excited by glass,
on approaching them with another excited body,
if they are attracted, then we know that the
second body has negative excitement — if re-
pelled, positive excitement is found.
The gold-leaf electrometer (fig. 139,) is,
however, a much more delicate test of electri-
cal excitement. It consists of two leaves of
gold, suspended in an air-jar, and communi-
j eating by a wire with a small plate of brass ;
' the approach to this plate of a body in any
degree excited, will occasion an immediate
movement of the gold-leaves, from which we
can tell the nature of the excitement, as
above described, having previously imparted
to the gold-leaves a particular kind of elec-
tricity.
168. ColomVs torsion electrometer, (fig.
140,) allows of the exact measurement of
quantities of electricity. A slender rod of
gum-lac (j, with ends of gilt pith, is suspend-
ed within a glass shade a by a filament of
I glass depending from the tube/. Another
bar of lac, also with gilt pith-balls, (called
Fig. 140. the carrier-bar,) is introduced at pleasure
Fig. 139.
What is an electroscope ? Describe the gold-leaf. 168. Describe Co.
tomb's electrometer, fig. 140. What does it enable us to do ?
Digitized
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ELECTRICITY OF JPEICTION. 109
by an opening o in the cover of the instrument. By a screw
t at top the needle may be adjusted. When unexcited, the
needle and carrier-bar stand in close proximity. To mea-
sure electricity by this instrument, the lower ball of the
carrier-rod is charged and introduced into the cylinder. It
will repel the movable ball in proportion to the intensity of
the charge ; and by turning the milled head at m we may
measure the degree of deflection, or torsion, of the thread
of glass. This we can also note on the graduated circle upon
the cylinder.
169. Conductor* and Insulators of Electricity. — The
pith-balls or glass tubes, which have been electrically ex-
cited, return to a natural state very slowly indeed, if left
untouched, in dry air. But the hand, or a metallic rod,
will at once restore them to the unexcited state, while dry
silk, glass, and resin will not remove the excitement.
Bodies are, therefore, divided into conductors and non-con-
ductors of electricity, or, more properly, into good and bad
conductors. The electrical discharge takes place through
good conductors (as the metals) with an inconceivable
velocity, which can be compared only to the velocity of
light. Among good conductors, in the order of their con-
ducting power, are the metals, charcoal, plumbago, and
various fused metallic chlorids, st^ng acids, water, damp air,
vegetable and animal bodies ; among bad or imperfect con-
ductors are spermaceti, glass, sulphur, fixed oils, oil of tur-
pentine, resin, ice, diamond, and dry gases. The latter
substances are also called insulators, because by their aid we
tan insulate or confine electricity.
170. The distribution of electricity in an excited body is
apon the surface. In proof of this, if on the insulated
stand b (fig. 141) we excite a spherical
body c c, provided with glass handles,
we may separate its halves and observe _.
that the inner sphere a has no excite- If
ment whatever. All the electricity ^mk>
remains on the outer surface. If the tfig. hi.
body is egg-shaped, the excitement becomes more concen-
trated in the extremities. A small point at the end of the
prime conductor will convey off all the excitement of a power-
169. What are conductors and insulators ? Name some of each, 170. How
Is electricity distributed ? Describe fig. 141; What is true of a point on
the prime conductor ?
, 11 VU. bUO lUBUUkbCU
Digitized
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110 ELKCTRICITY.
ful machine insensibly, unless in the dark, when a track of
light will be seen proceeding from the point.
The excitement of a powerful machine may be
withdrawn by pith-balls, or figures of pith ar-
ranged as is figure 142, which convey away the
electricity as fast as it is produced — being at-
tracted and repelled between the two surfaces.
171. Lightning conductors were devised by
Dr. Franklin, after his memorable experiment
with the kite, by which he proved the identity of _
atmospheric electricity with that of machine ex- e
citation. The efficacy of lightning conductors, Fi«-142-
now so general, depends on the power of a point to draw
away insensibly very powerful charges of electricity. It is
essential that they should be well insulated, and that the
lower end should enter so deep into the earth as always to
be in damp ground.
172. Two theories have been proposed to explain the
ordinary phenomena of electricity. The first is called the
Franklinian hypoiliesis, proposed by our distinguished
countryman, Dr. Franklin. It supposes that there is a
simple, subtle, and highly-elastic fluid, which pervades all
matter. This fluid is self-repellent, but attracts all matter,
or its ultimate particles. In the natural state of bodies,
this fluid is uniformly distributed over them, and its in-
crease or diminution produces electrical excitement. Ac-
cordingly, when a glass tube is rubbed with a silk hand-
kerchief, the electrical equilibrium is disturbed, the glass
acquires more than its natural quantity, and is over-charged,
the silk possesses less, and is under-charged.
The second hypothesis is that of Du Fay, who assumes that
electrical phenomena are due to two highly elastic, impon-
derable fluids, the particles of which are self-repellent, but
attractive of each other. These two fluids exist in all un-
excited bodies in a state of combination and neutralization,
when no electrical phenomena are seen. Friction occasions
the separation of the fluids, and the electrical excitement in
a body continues until an equal amount of opposite electri-
city to that excited has been restored to it.
How do the dancing figures discharge electricity? 171. How do
lightning conductors act? 172. What is the Franklinian hypothesis?
What is that of Du Fay ?
Digitized
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ELECTRICITY OP FRICTION.
llj
According to Dr. Franklin's theory, the two states am
denominated positive and negative ; according to Da Fay,
they are distinguished as vitreous and resinous.
Whichever theory we may adopt, we can clearly see how
it is impossible ever to develop one electrical condition
without at the same time giving rise to the other.
173. The Ley den jar was invented by Cunasus, of
Leyden, in 1746. By it the experimenter collects and
transfers a portion of the electricity evolved by his machine,
and applies it to the purposes of experiment. It is simply
a glass jar, (fig. 143,) covered inside and out with tin-foil up
to the line seen in the figure. A brass ball
communicates by a wire and chain with the in-
terior coating, the mouth being stopped by a
cover of dry wood. On approaching the ball
to the conductor of the electrical machine,
when in action, a series of vivid sparks will be
received by it, and a great accumulation of
vitreous electricity takes place in the interior,
provided the exterior be not insulated. On
forming a connection by a conductor between
the interior and exterior surfaces, the equili-
brium is at once restored by a rush of the op-
posing forces, accompanied with a brilliant flash of artificial
lightning. If the hand of the operator is the conducting
medium, a violent shock is felt, commonly known as the
electrical shock. A series of such jars, arranged so as to be
charged by one machine, is called an electrical battery, as
shown in figure 144, where all
the inside coatings unite, and
also all the outsides are con-
nected. The battery may also
be so constructed as to allow of
the jars, after they are charged,
being shifted so that the series
shall be discharged consecutive-
s— ly, each outer connected with
the next inner coating. Great
intensity is thus obtained.
Fig. 144.
What terms describe these conditions? 173. What is the Leyden
)ir ? What its theory ? What is an electrical battery 1
112 ELECTRICITY.
174. By using an insulated
? Y jointed rod, fug. 145,) called a
\ I discharging roa, the experimenter
\ / avoids receiving the shock.
\* «/ When the shock of the electri-
^^■^^ cal battery is passed through
a card, (fig. 146,) the hole which is
Fig. 145. pierced is burred on both sides.
This fact has been adduced as a proof that there
were two fluids, moving in different directions.
Otherwise it would seem that the burr should
exist only on one side.
175. The dissected Leyden jar (fig. 147) is Fig. 146.
so constructed that we may remove the interior
coating from its glass jar b, leaving the outer coat-
ing alone. This may be done after the jar is
charged, when the separate parts will not manifest
excitement, as tested by the electroscope. When
reunited, however, a spark can still be drawn
from it.
If the Leyden jar is placed on an insu-
lating stand «, (fig. 148,) it will be found
impossible to charge it. The most power-
ful machine a will communicate only one or
[C^ two sparks to it, 6. This is because the
■ ' I negative excitement cannot pass off from
the outer coating. Accordingly, if the ball
i JL of a second jar c, uninsulated, be brought
Fig. 148. near tDe outer coating, a torrent of sparks
flows off, and both jars are quickly charged. Attention to
the laws of attraction and repulsion gives us an easy solu-
tion of this problem, which involves the whole theory of the
Leyden jar. It is also obvious that glass is not an impedi-
ment to the induction of electrical excitement, however per-
fect it may be as a non-conductor.
176. Dr. Faraday has shown that the inductive action of
ordinary electricity takes place in curves which are analo-
gous to the lines of force surrounding a magnet — forming its
atmosphere of influence, so to speak.
174. What is a discharging rod? What does the card experiment
show ? 175. What is the dissected jar ? Describe the experiment in
fig. 148. 176. How does electrical induction occur? Name the induc-
tive power of glass, lac, sulphur, Ac.
Digitized
byGoogk
ELECTRICITY OF FRICTION. 113
Substances also differ in their specific power of inductive
capacity : thus, air being unity, the inductive capacity of glass
is 1-76, of lac 2, and of sulphur 2-25. All gases also have
the same inductive capacity, however they may differ in
density or other respects.
177. The Electrophorus is a convenient mode of obtain-
ing an electrical spark, when no
electrical machine is to be had,
and consists of a shallow tray
of tin, the size of a dining plate,
partly filled with melted shellac ,
a, or some other resinous pre-
paration, made as smooth as
possible. A disc of brass 6, Fig. 149.
with a glass handle, is provided, and the bed of resin is
rubbed with a dry flannel or cat-skin : this excites negative
electricity, and the metal disc is then laid on the excited
surface, and touched with the finger, which receives a nega-
tive spark. A coating of positive electricity is induced on b,
which may be raised, and discharged by a conductor, giving
a vivid spark, sufficient to explode gases. The resinous
electricity not being conducted away from the shellac, the
spark may be repeated as long as the excitement lasts. It
is plain that the electricity in this case is induced by the
excited lac.
If a mixture of red-lead and flowers of sulphur, previously
well mixed in a mortar, be blown from a tube over the ex-
cited surface of the electrophorus, the two substances are
immediately separated, because of their opposite electrical
relations, and are arranged in curious figures on opposite
sides of the excited disc.
178. A jet of high steam, issuing from a locomotive or
other insulated steam-boiler, will, with certain precautions,
give a stream of electrical sparks more powerful than any
electrical machine. This has been called hydro-electricity,
and is produced by the friction of the hot steam on the
edges of the orifice from which the steam issues.
177. What is the electrophorus? What is its theory? How dow
led-lead, Ac. behave on it ? 178. What is hydro-electricity ?
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114
ELECTRICITY.
Galvanism, Voltaism, or Electricity of Chemical Actum.
179. History. — Galvani, of Bologna, in the year 1790,
accidentally observed that the freshly denuded legs of a frog,
suspended on a metallic conductor, were powerfully con-
vulsed when brought near to an active electrical machine.
From this trivial observation has sprung one of the most
wonderful departments of human knowledge. The same
fact had been previously noticed, and Swammerdam had
exhibited it before the Grand Duke of Tuscany, but no
result of value was deduced from it. It was suggested that
there was a peculiar sensitiveness to electrical excitement
in animal substances, due to some remaining vital energy.
This explanation failed to satisfy Galvani, who observed
similar convulsions in the frog's limbs when
. hanging from a copper wire b (fig. 150) on
_* an iron rail. He found that the effects were
produced whenever the muscles touched the
iron while the nerves touched the copper, but
that contact with the copper alone did not
produce them. The crural nerves are easily
exposed by separating the large muscles with
the fingers at a a. From his observations,
Galvani inferred that there was a peculiar
variety of electricity in animals, which he
called animal electricity — that this was de-
veloped whenever connection was made be-
tween the muscle and naked nerve by means
of two metals. This theory fascinated the
physiologists, and for ten years Galvani's experiments wero
repeated with great zeal in all civilized countries.
180. Volta, of Pavia, maintained that it was the contact
of two metals which generated the electricity, of which the
frog's legs were only a delicate electroscope. This experi-
ment can never fail to excite wonder, however often we may
perform it. We suspend from a metallic conductor a pair
of frog's legs recently skinned, and with a part of the spino
attached. With two metallic slips, one of zinc and one of
copper, we touch at the same time the naked nerve and the
179. What was Galvani's observation? What was the suggestion?
What did Galvani infer? How was his animal electricity excited
180. What did Volta maintain? What was his observation with the
frog's legs ?
Fig. 150.
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ELECTRICITY OP CHEMICAL ACTION.
115
Fig. 151.
muscle, as shown in fig. 151. Convulsions
immediately throw the limbs into the po-
sition indicated by the dotted lines ; and
we may repeat the trial until, after a time,
this power gradually dies out. In proof
of his views, Volta invented and brought
forward his memorable pile, of which a
more particular mention will be made
presently.
181. This is not the place to record in detail the history
of science, but this discovery is one of the few grand
achievements of the human mind which must ever mars
the moment of a new era in experimental philosophy. It is
both wonderful and instructive to reflect that so simple an
observation as the twitching of a frog's legs should have led
immediately to a revelation of the metallic basis of the en-
tire crust of our planet — to the adoption of a new classifica-
tion of elements and of their compounds — to almost mi-
raculous performances in metallurgy — and to the instanta-
neous communication of thought, by the annihilation of
time and space !
182. Voltaic Pile. — Volta sagaciously reasoned that the
effects observed by Galvani could be produced with simple
metals and a fluid, or substances saturated with a fluid. The
truth of this conjecture is easily verified by placing on the
tongue a silver coin, and beneath it a slip of zinc or a cop-
per coin. On touching the edges of the two metals so
situated, we perceive a mild flash of light and
a sharp prickling sensation or twinge, giving
notice of the production of a voltaic current.
This simple experiment was made long before
the discoveries of Galvani and Volta, and is
to be regarded as the first recorded observation
in the remarkable science of galvanism. Volta
accordingly arranged a series of copper and
Bilver coins in a pile, with cloths wet in a
saline or acid fluid between them. The ar-
rangement is seen in fig. 152. The copper c
and zinc z alternate with the wet cloth be-
Pig. 152.
tween. The pile begins with z and ends with c, and care
What did he invent? 181. What reflection is here made ? 182. What
was Volta'a reasoning ? What is tho simplest form of battery?
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116 ELECTRICITY.
must be taken that the order be strictly maintained, viz.
copper — cloth — zinc. On establishing a metallic commuii*
cation between these extremes (poles) by a wire, a current
of electricity flows in the direction of the arrow on the wire.
If orfe hand be placed on each end of the pile, a shock
will be experienced, similar in some respects to that from
the electrical, machine, and yet very unlike it. If the pile
has many members, on touching the wires communicating
between the extremes the shock is very intense, and a vivid
spark will be produced, which is increased if points of pre-
pared charcoal are attached to the ends of the wires. The
conducting wires held together will grow hot, and if a short
piece of small platina wire is interposed, it will be heated
to bright redness. Such is an outline of the remarkable
discovery of Volta, whose pile was made known to the
world in 1800. The principle involved in this arrangement
is unaltered, although more manageable and efficient forms
of apparatus have supplied the place of the original pile.
183. Simple Voltaic Circle. — A voltaic current is esta-
blished whenever we bring two dissimilar metals (as copper,
silver, or platina, with zinc or iron) into contact in an acid
or saline fluid. Thus, if we place a slip of
copper in a glass of acid water, and beside it
in the same vessel a slip of amalgamated zinc,
(fig. 153,) as long as the two metals do not
touch there will be no action, but on bringing
together the upper ends of the two slips of
metal, a vigorous action will commence, bub-
bles of gas will be rapidly given off" from the
Fig. 153. copper, while the zinc will be gradually dis-
solved in the acid water. This action will be arrested at
any moment, on separating the two metals. If this separa-
tion is made in the dark, a minute spark will also be seen.
The action here is entirely electrical. The end of the* zinc
in the acid is +, or positive, and that in the air — , or ne-
gative ; the copper has the reverse signs. These relations
are expressed in the figures by the signs -f- and — , and by
the direction of the arrows showing the -f- electricity of the
zinc passing to the — of the copper in the acid ; while the
bubbles of gas (hydrogen) set free at the -J- end of the zino
Describe the pile, fig. 152. 183. What axe the conditions of a voltaia
circuit? How is its action suspended? What are the electrical states of
the immersed metals ? Illustrate by figs. 153, 154.
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ELECTRICITY OP CHEMICAL ACTION.
117
Fig. 154.
are delivered at the — of the copper. Fig. 154 shows how
the current may be established by wires,
without the direct contact of the slips. In
this case the wires (as in the pile) carry the i
influence in the direction of the arrows, and
the existence of the current and its positive
and negative characters may be shown by
the effect produced by it on a small mag-
netic needle, which will be influenced by
the wires carrying the current, just as by
the magnet — being attracted or repelled
according as it is above or below the wire,
and in either case endeavoring to place itself at right angles
to the conducting wire, (201.) The direction of the voltaic
current (and of course the + or — qualities of the metals
from which it is evolved) depends entirely on the nature of
the chemical action produced. Thus, if, in the arrangement
just described, strong ammonia were used in place of the
dilute acid, all the relations of the metals and the fluid
would be reversed, since the action would then be upon the
copper.
184. Thus is electricity the result of chemical action;
and conversely we see that, under the arrangement described,
chemical action is controlled by the electrical condition of
the metals. This is electricity in motion, or dynamic elec-
tricity; and frictional electricity may be regarded as stag-
nant or statical electricity. Let us attend somewhat further
to the theory of the voltaic circle.
185. In the compound voltaic circuit, composed of two
or more members, connection is formed, not between members
of the same cell, but between those of opposite names
in contiguous cells.
This is seen by in-
specting the arrows
and signs -f- and —
in figure 155. The \
electricity always
flows, both in simple
and compound cir-
cles, from the zinc
to the copper, in the
Fig. 155.
184. How is this mode of electricity regarded ? 185. What are the con-
ditions of a compound voltaic series ? Describe it in fig. 155.
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118 ELECTRICITY.
fluid of the battery; and from the copper to the zinc, oat
of the battery. This is important to be remembered, since
the zinc is called the electro-positive element of the voltaic
series, although out of the fluid it is negative ; and conse-
quently, in voltaic decomposition, that element which goes
to the zinc-pole is called the electro-positive element, being
attracted by its opposite force; while the element going
to the copper is called, for the same reason, the electro-
negative. The compound circle, reduced to the simplest
form of expression, would be —
Copper — zinc — -fluid— copper — zinc.
Here the copper end is negative and the zinc positive,
but the two terminal plates are in no way concerned in the
effect ; so that, throwing them out of the question, we bring
it to the state of the simple circle, which is simply —
Zinc — fluid — copper ;
and here we find the zinc end negative, and the copper end
positive.
186. A certain resistance to the passage of a voltaic cir-
cuit is offered by every element used in its construction.
New properties are thus acquired by the compound circuit,
which are never seen in the single couple, while the latter
possesses certain attributes not seen so well in the compound
series. For example, no single pair of plates, however large,
will afford a current capable of decomposing water or of
affording an electrical shock, although a maximum of mag-
netic effect may thus be produced. These differences were
formerly ascribed, rather vaguely, to what has been called
quantity and intensity. Thus, in the compound circuit,
supposing each -f- and — in the circuit to neutralize each
other, then only the final quantities -f- and — remain as
expressed in the poles; and it was argued that the quantity
of electricity was no greater than would be afforded by a
single couple, while its intensity, owing to the resistance over-
come in each cell, was greatly increased. This matter has
been placed on the basis of mathematical demonstration by
187. Ohm's Law.— Ohm, of Berlin, in 1827 first de-
monstrated that, as the voltaic apparatus itself is composed
186. What effect is due to each element ? "What new properties does
the current thus acquire? What was meant by quantity and intensity ?
1S7. What law expresses the conditions of a voltaic circuit ?
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ELECTRICITY OP CHEMICAL ACTION. 119
solely of conductors, the electric current must proceed, not
only along the connecting wire, from pole to pole, but also
through the whole apparatus ; that the resistance offered to
the passage of the current consisted therefore of two parts,
one exterior to, and one within, the apparatus. This expla-
nation cleared up at once the difficulties which had previously
beset this subject when regarded only in view of the exterior
resistance.
Let the ring a b c in fig. 156 represent a homo- a.
geneous conductor, and let a source of electricity ^^^\
exist at A. From this source the electricity will / \
diffuse itself over both halves of the ring, the I J
positive passing in the direction a, the negative x^_^/
in b, and both fluids meeting at c. Now it fol- . *
lows, if the ring is homogeneous, that equal quan- **£• 156#
tities of electricity pass through all cross sections of the
ring in the same time. Assuming that the passage of the
fluid from one cross section of the ring to another is due to
the difference of electrical tension at these points, and that
the quantity which passes is proportional to this difference
of tension, the consequence is that the two fluids proceeding
from A must decrease in tension the farther they recede
from the starting point.
188. This decreasing tension may be represented by a
diagram. Suppose the ring in fig. 156 to be stretched out
to the line A A'. Let the ordinate
A B represent the tension of positive
electricity at A, and A' B' that of the
negative fluid; then the line BB'
will express the tension for all parts
of the circuit, by the varying lengths
of A B, A' B' at every point of A c or FI* w"
c A'. Hence Ohm's celebrated formula, F = ■?, where F
represents the strength of the current, E the electro-motive
force of the battery, and R the resistance. Therefore the
greater the length of the circuit, the less will be the amount
of electricity which passes through any cross section in a
given time. In exact terms, this law states that the strength
Demonstrate fig. 156. 188. How do you express the decreasing ten .
lion ? What is Ohm's formula ? Give the meaning of each expression.
What is the Ian as stated?
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120 ELECTRICITY.
of the current is inversely proportional to the resistance of the
circuity and directly as the electro-motive force.
189. Bat in the simplest voltaic circuit we have not a
homogeneous conductor, but several of various powers in
this respect. To illustrate this, let the
conductor A A' (fig. 158) consist of
two portions having different cross
sections. For example, let the cross
section of A d be n times that of d A! ;
then if equal quantities pass through
Pig. 158. all sections in equal times, if through
a given length of the thicker wire no more fluid passes than
through the thinner wire, the difference of tension at both
ends of this unit of length of the thicker wire must be only
-th of what it is in the latter. Thus, " the electric fall/' as
w . .
Ohm calls it, will be less in the case of the thick wire than
of the thinner, as shown by the line B a in the figure. The
result is expressed in the law that the " electric fall" is
directly as the specific resistances of the conductors, and in-
versely as their cross sections. Hence, the greater the resist-
ance offered by the conductor, the greater the fall. The
very simplest circuit must therefore present a series of gra-
dients expressive of the tension of its various points — as
one for the connecting wire, one for the zinc, one for the
fluid, and one for the copper. The electro-motive force of
a voltaic couple (" E" of Ohm's formula) may be experi-
mentally determined, and it is proportional to the electric
tension at the ends of the newly broken circuit.
190. Galvanic Batteries are constructed of various forms,
according to the purpose for which they are to be used.
One of the earliest
forms contrived was the
Cruiekshank's trough,
(fig. 159,) in which the
plates of copper and
lg* * zinc soldered together
are secured in grooves by cement, water-tight, all the zincs
facing in one direction. The acid was poured into the
189. How does it apply to conductors not homogeneous ? What is the
electric fall ? Give the law. Describe the course of tbe current in and
out of the fluid. What is the simplest expression of the compound
circle ? 190. What was Cruiekshank's battery ?
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ELECTRICITY OF CHEMICAL ACTION. . 121
trough until the cells were filled. To avoid the incon*
veuience arising from loss of power, (which in this form of
instrument is greatest at the first moment of contact be-
tween the plates and the acid,) Dr. Hare contrived his
revolving deflagrators. These were so constructed, that hy
a quarter revolution of the trough, the acid could at plea-
sure, and without disturbing the arrangements of the
operator, be thrown off or on the plates, and the maximum
effects of this kind of the battery be obtained. But
recent improvements in the construction of the battery have
supplied us with several superior forms of the instrument,
suited to various purposes, and possessing the valuable qua-
lity of constancy of action.
191. Amalgamation, — In the original form of the gal-
vanic battery, made of copper and of unamalgamated zinc,
there is a great amount of local action in each cell, arising
from the impurity of the zinc. When the surface of the
sine is amalgamated with mercury, the local action ceases ;
and the amalgamated surface, being reduced to one uniform
electrical condition, will remain for any length of time in
the acid fluid unacted on, until connected with the electro-
negative element. All improved batteries are therefore now
constructed with amalgamated zinc. It should be remarked
that the heal action in a battery cell, arising from the
cause named, not only consumes the power of that member,
but reduces the energy of the whole series. In order to
have a constant voltaic circuit of equal power, not only the
evils arising from local action must be avoided, but also, as
far as possible, the exhaustion of the fluid of excitation.
Batteries so constructed as to meet these difficulties are
called sustaining batteries, or constant batteries. Some of
the more important of these we will briefly describe.
192. Smee's Battery is formed of zinc and silver, and
needs but one cell, and one fluid to excite it. The silver
plate (S, fig. 160) is prepared by coating its surface with
platinum, thrown down on it by a voltaic current, in the
state of fine division, which is known as platinum-black.
The object of this is to prevent the adhesion of the liberated
hydrogen to the polished silver. Any polished smooth sur-
face of metal will hold bubbles of gas with great obstinacy,
What was Hare's improvement ? 191. What is amalgamation ? What
its use ? What is said of local action ? 192. What is Smee's battery ?
122
ELECTRICITY.
^ thus preventing in a measure the contact
between the fluid and the plate by the in-
terposition of a film of air-bubbles. The
roughened surface produced from the de-
posit of platinum-black entirely prevents
this. The zinc plates z z in this battery
arc well amalgamated, and face both sides
of the silver. The three plates are held in
position by a clamp at top b, and the
interposition of a bar of dry wood w
i prevents the passage of a current from
plate to plate. Water, acidulated with
one- seventh its bulk of oil of vitriol, or,
for less activity, with one-sixteenth, is the
exciting fluid. The quantity of electricity excited in this
battery is very great, but the intensity is not so great as in
those compound batteries to be described. This battery is
perfectly constant, does not act until the poles are joined,
and, without any attention, will maintain a uniform flow of
power for days together. A plate of lead, well silvered, and
then coated with platinum-black, will answer equally as
well, and indeed better than a thin plate of pure silver
This battery is recommended over every other for the stu-
Fig. 160.
Fig. 161.
dent, as comprising the great requisites of cheapness, ease
of management, and constancy. A form of it, well calcu-
lated for the student's laboratory, is shown in fig. 161,
which is a porcelain trough with six cells. This battery is
the one universally employed in electro-metallurgy. '
193. DanieWs Constant Battery. — This truly philosophi-
cal instrument (fig. 162) is made up of an exterior circular
What are the advantages of Smee's battery ?
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ELECTRICITY OP CHEMICAL ACTION.
123
Fig. 162.
coll of copper C, three and a half inches in diameter,
which serves both as a containing vessel and as
a negative element ; a porous cylindrical cup
of earthenware P (or the gullet of an ox tied
into a bag) is placed within the copper cell,
and a solid cylinder of amalgamated zinc Z
within the porous cup. The outer cell C is
charged by a mixture of eight parts of water
and one of oil of vitriol, saturated with blue I
vitriol, (sulphate of copper.) Some of the solid
sulphate is also suspended on a perforated shelf,
or in a gauze bag, to keep up the saturation.
The inner cell is filled with the same acid |
water, but without the copper salt. Any num-
ber of cells so arranged are easily connected I
together by binding screws, the C of one pair
to the Z of the next, and so on. This instru-
ment, when arranged "and charged as here described, will
give out no gas. The hydrogen from the decomposed water
is not given off in bubbles on the copper -side, as in all forms
of the simple circuit of zinc and copper ; because the sulphate
of copper there present is decomposed by the circuit, atom
for atom, with the decomposed water, and the hydrogen
takes the atom of oxyd of copper, appropriating its oxygen
to form water agaiu, and metallic copper is deposited on
the outer celL No action of any sort results in this battery,
when properly arranged, until the poles are joined. Ten or
twelve such cells form a very active, constant, and econo-
mical battery.
I94r. Iti the common sulphate of copper battery (fig. 163)
only the acid solution of sulphate of copper is *\
used. The surface of zinc becomes soon en-
cumbered by the metallic copper in a state of -
fine division thrown down upon its surface.
It is a very useful battery for electro-mag-
netic purposes.
195. Grove's Battery. — Mr. Grove, of Lon-
don, has contrived a compound sustaining lg*
battery, of great power and most remarkable intensity of
action. The metals used are platinum and amalgamated
193. What is Darnell's battery? 194. What is the sulphate of coppei
battery ? What is Grove's battery ?
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124
ELECTRICITY.
Fig. 164.
zinc. A vertical section of this battery is shown
in fig. 164. The platinum -f- is placed in a
porous cell of earthenware, containing strong
nitric acid. This is surrounded by the amalga-
mated zinc — in an outer vessel of dilute sul-
phuric acid, (six to ten parts water to one of
acid, by measure.) The platinum, being the
most costly metal, is here surrounded by the
zinc, in order to economize its surface as much
as possible. In this battery the hydrogen of
the decomposed water on the zinc side enters the
nitric acid cell, decomposes an equivalent of the
acid, forming water with one equivalent of its
oxygen, while the deutoxyd of nitrogen is given out as a
gas, and, coming in contact with the air, is converted into
hyponitric acid fumes. No other form of battery can be com-
pared with this for intensity of action. A scries of four
cells (the platinum foil being only three inches long and
half an inch wide) will decompose water with great rapidity;
and twenty such cells will evolve a very splendid arch of
light from points of prepared charcoal, and deflagrate all
the metals very powerfully. It is rather costly, and trouble-
some to manage, as are all batteries with double cells and
porous cups.
196. Bunsen-8 carbon batteiy is a valuable addition to our
resources in this department. It employs a cylinder of car-
bon for the negative element, in place of the
platinum in Grove's battery. The carbon is
] that of the gas-works, pulverized and mould-
| ed with flour, and afterward baked like pot-
| tery into compact cylinders. This battery
(fig. 165) has the advantage of large mem-
bers and great cheapness of construction.
Fifty large-sized members, 10 inches high,
the outer cups 5 inches in diameter, cost
about fifty-five dollars in Paris, made by Deleuil, Rue du
Pont-de-Lodi, No. 8. The author has found this, on the
whole, the most efficient and economical of all batteries
suited to show the more splendid and intense effects of
voltaic electricity.
Fig. 165.
196. What is Bunsen's battery ? What is the reaction in these com-
pound batteries ?
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ELECTRICITY OP CHEMICAL ACTION,
125
197. The effects of voltaic electricity are,
1. Physical; 2. Chemical; and, 3. Physio-
logical. Under the first head are included
the electrical, luminous, calorific, and elec-
tro-magnetic phenomena of the circuit.
198. Deflagration. — When the current
from a series of 20 or 50 pairs of Grove's
or Bunsen's battery is passed through
points of prepared charcoal, as in the dis-
charger, (fig. 166), a most brilliant light
and intense heat are produced. No effect
is seen until contact is made between the
polesp and n, when, on withdrawing them,
the arch of light elongates, and connects
the separated poles, in
the manner shown in
fig. 167. This arch is
in a powerful pile some
inches in length. It is
accompanied with an -™- ,
elongation of the pole "*■
on the — or carbon «*i«\ Fi*m
side of the battery, and a depression or hollow-
ing out of the -f- or zinc side. This flame is
a conductor of electricity, and is attracted and
repelled by the magnet, as shown in fig. 168.
By holding a magnet in a certain position the
flame may be made to revolve, accompanied
at the same time with a loud sound. In the
small capsule of carbon S, (fig. 169,) gold,
platinum, steel, mercury, and other sub-
stances are speedily fused and deflagrated, with
various colored lights and volatilization. The
easy fusion of platinum by the pile is a proof of
the intensity of the heat, as this effect can be pro-
duced by no other source of heat known, except
that of the oxy hydrogen blowpipe. By the union
of the currents from several hundred carbon cells,
M. Despretz has lately volatilized the diamond.
The ingenuity of the teacher will vary the ex-
periments, always so surprising and instructive.
Fig. 166.
Fig. 169.
Fig. 170.
197. Classify the effects of voltaic electricity,
oi deflagration. Which polo elongates ?
198. Describe the effects
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126
ELECTRICITY.
199. The electrical light of the voltaic
circuit is in no degree dependent on com-
bustion, as may be proved by establishing
connection between the poles in a vacuum
in a glass vessel exhausted by the air-pump,
and containing the poles conveniently ar-
ranged, as in fig. 170. No less brilliancy
is perceived in this case than in the air.
200. A constant light is produced from
the battery of Grove or Bunsen, by an in-
genious mechanical arrangement of the
poles. Fig. 171 shows that of M. Du-
boscq, of Paris. The poles S and I are
preserved at the same distance by the ac-
tion of an electro-magnet in the foot E,
upon a soft-iron bar F F in connection with
an endless screw V, moving the pullies
P P, which are connected by cords with
the poles S and I. The contact of S and
I induces magnetism in the electro-magnet
E, while the springs E L regulate the mo-
tion of the machinery* The apparatus is
simple and portable, and its effect is to
make the electrical light so steady and con-
stant that it may be used for all optical ex-
periments. The author has also shown
that good daguerreotypes may be taken
with it in a few seconds. For this pur-
pose the light is concentrated by a large
parabolic mirror, so placed that the poles
meet in its focus. The positive pole con-
sumes much more rapidly than the nega-
tive, both from a more intense action upon
it and because its particles are carried over
and deposited on the negative pole, elon-
gating the point of the latter. To provide for this difference!
the pulley P is variable, and carries the pole I up propor-
tionably faster, so that the focal position of the light remains
unchanged.
Fig. 171.
How does a magnet affect the are of flame ? 199. How does a vacuum
affect the electrical light? Describe fig. 170. 200. What is the arrange-
ment for rendering the light constant? Describe fig. 171.
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ELECTRO-MAGNETISM. 12)
Ekctro-Magn etism*
201. Prof. (Ersted, of Copenhagen, in 1819 first made
known the law of electro-magnetic attraction and repulsion.
If a wire conveying a voltaic current is brought above and
parallel to a magnetic needle, (as shown in ' >■
fig. 172,) the latter is invariably affected, ^r
as if influenced by the poles of another <c II - in
magnet If the current is flowing, as in- >
dicated by the arrow on the wire, say to
the north, then the north pole of the
needle will turn to the east ; if the current _T**_t
is flowing south, it will turn to the west. /*~^
If the wire carrying the current is placed Fl** 172#
beneath the needle, the same effect is produced as if the
current had been reversed ; the needle turns in the opposite
way to what it does when the wire is above. The effort of
the needle is to place itself at right
angles to the wire, as if influenced
by a tangential force. That the wire
conveying a voltaic current is itself
magnetic, is proved by this experi-
ment. If the wire is bent in a rect-
angle, as in fig. 173, and wound with Fig. 173.
silk or cotton, to prevent metallic contact, and the lateral
passage of the power from wire to wire, then it is evident
that a current flowing over the wire will
have to pass many times completely
around the needle, and the effect which
is produced will be nearly in proportion
to the number of turns made by the wire.
In this way we can make a very feeble
current give decided indications. Such
an arrangement is called a galvanoscope
or galvanometer.
202. In delicate galvanoscopes, in order _________
to free the magnetic needle from the di- Fig. 174.
rective tendency which it receives from
the earth's magnetism, two needles are used, with their
unlike poles placed opposite to each other, (fig. 174,) one
201. Who discovered electro-magnetism ? What effect has a current on
a wire ? What is meant bj a tangential force ? What is a galvanometer ?
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128
ELECTRICITY.
Fig. 175.
within and the other above the coil. They will then hang
suspended by the silk fibre which supports them, with no
tendency to swing in any direction, since they are wholly
occupied with their own attractions
and repulsions, and their directive
power is neutralized. Consequently,
they are free to move with the slight-
est influence of any current passing
through the coil. Such an arrange-
ment is called an astatic needle. To
give it greater delicacy, and prevent
the currents of air from moving it,
a glass shade (fig. 175) is placed over
it, and the movements of the needle
are read on the graduated circle. By
I means of a screw provided for that
purpose, the coil is revolved until it is
parallel with the needle, as the point
of greatest sensitiveness. The ten-
dency of the galvanometer needle, it will be remembered,
is always to place itself at right angles to the direction of
the electrical current, that position being the equator of the
attracting and repelling powers, and consequently a point
of equilibrium.
203. Ampere's Theory. — In 1820, while the original dis-
covery of OSrsted was attracting the greatest attention, M.
Ampere, of Paris, proposed to account for the phenomena
of terrestrial magnetism by supposing a series of electrical
currents circulating about the earth from east to west, in
spirals nearly at right angles to its magnetic axis. The
sun's rays impinging on the surface of the earth, encircle it,
so to speak, with an unending series of spiral lines, pro-
ducing, by thermo-electricity, the phenomena of magnetic in-
duction. Arago found, in accordance with these views,
that if iron-filings were brought near a connecting wire
while a voltaic current was passing, that they adhered to it
in concentric rings. These fell off the moment the circuit
was broken. Hence it was inferred that if a voltaic current
was made to pass in a spiral about any conductor/ it would
become magnetic. This inference was verified by the
202. What is an astatic needle ? How is it freed from the influence
of terrestrial magnetism ? 203. What was Ampere's theory ? What de-
monstration did M. Arago devise?
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ELECTRO-MAGNETISM.
129
Fig. 176.
204. Edix. — A wire coiled as in fig. 176, made the me-
dium of communication for a voltaic current, becomes ca-
pable of manifesting very strong
magnetic influence on any con-
ductor placed in its axis. A
delicate steel needle, laid in the
helix, will be drawn to the
centre and held suspended there,
without material support, like
Mahomet's fabled coffin. If the needle is of steel, the mag-
netism it thus receives will be retained by it ; but if it be
of soft iron, it is a magnet only while the current is passing
Brass, lead, copper, or any other metallic conductor, can by
galvanism be made to manifest temporary magnetic power.
The polarity of the needle in the helix will depend on the di-
rection in which the current is carried; if from right to left, the
south pole will be at the zinc end ; if from left to right, this
polarity is reversed. If the spiral is reversed in the middle,
then a pair of poles will be found at the
point of reversal, and this as often as the £
reversal may happen. A steel needle placed J>
in such a helix receives the same reversals. J1
Such an arrangement is shown in fig. 177. 4
205. The polarity of the helix is well
shown by the arrangement represented in
fig. 178, called De la Rive's ring. A small
wire helix, whose ends are attached to the
little battery of zinc and copper con-
tained in a glass tube, floats on the
surface of a basin of water, by means
of a large cork, through which the
glass tube is thrust. On exciting
this small battery by a little dilute
acid, poured into the tube, and
placing the apparatus on the water,
it will at once assume a polar direc- F. 178
tion, as if it were a compass-needle,
the axis of the helix being in the magnetic meridian ; and
it will then obey the influence of any other magnet brought
near it, manifesting the ordinary attractions and repulsions
204. What is the helix? How is a needle in it affected? What po-
larity has it ? What does fig. 177 illustrate ? Why are the poles reversed
at N ? 205. What shows the polarity of the wire itself? Describe fig. 17S.
Pig. 177.
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180
ELECTRICITY.
Fig. 179.
206. The helix is placed as in figure
179, its lower end dipping into a cup
of mercury p, in connection with one
pole kf while it is held by its upper
end n in connection with the other
pole. In this situation, when the cur-
rent passes, the separate turns of the
\ helix attract each other, thus shorten-
i ing the spiral and raising the point out
(of the mercury, with a vivid spark.
This breaks the connection — the un-
magnetized helix falls — the point again
touches the mercury, when a fresh contraction happens.
These effects are made very striking by holding one end of
an iron rod, or of a bar magnet, within the spiral. If a
magnetic bar is used, the vibrations obey the ordinary law
of polarity, ceasing entirely when a pole of like name is
introduced.
207. Electro-Magnets. — The induction of magnetism in
soft iron by the voltaic current, furnishes us the means
of producing magnets of astonishing power.
Let a b (fig. 180) be a cylinder of soft iron,
fitting the opening of a helix. If the cur-
rent from several Grove's batteries be passed
through the wires mn, sufficient magnetic
power will be developed to sustain a 6, oscil-
I lating in a vertical line, even should it weigh
eight or ten pounds. This is one of the most
surprising of all experimental demonstrations.
By the use of this arrangement on a large
scale, and with a battery of 100 members of platina, a foot
square, Dr. Page sustained a mass of soft iron 600 pounds
in weight, with a vertical movement of eighteen inches.
On this principle he has propelled a magnetic engine on a
railway at considerable speed, and sought to apply the power
to other mechanical uses.
208. Professor Henry first demonstrated the fact that the
power of an electro-magnet with a given voltaic current
was greatly increased when the helix wire was divided into
Fig. 180.
206. Explain the action of the helix in fig. 179. 207. What is an electro-
magnet? What remarkable result is mentioned? 208. What did Pro-
fessor Henry first show ?
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ELECTRO-MAGNETISM.
131
eoife of limited length. Availing himself
of this principle, he constructed electro-
magnets lifting over two thousand pounds,
with a single cylinder hattery of small
sice. All the corresponding ends of the
helices are carried to their appropriate
poles.
209. The ring helix (fig. 182) is a
striking mode of exhibiting the inducing
effect of a voltaic current. Here two
semicircles of soft iron, fitted with han-
dles, are magnetized by the current
passing in R, the ends ah being in con-
nection with a battery. The rings of iron
and of wire are quite separate, and, when
the current passes, the iron (about f inch
diameter) becomes so strongly magnetic
as to sustain, easily, 50 pounds. Small
electro-magnets have been made to sustain
420 times their own weight.
210. Electro-magnetic Motions. — Faraday
first produced motion by the mutual action
of magnets and conductors, and Prof. Hen-
ry, in this country, about the same time.
By various combinations of the principles
already explained, a great number of inge-
nious pieces of electro-magnetic apparatus
have been contrived for showing motion ; by
wires attracting and repelling — by circles
and rectangles of wires revolving the one
within the other — by armatures revolving
before the poles of permanent or electro-
magnets, and these adapted to carry various
forms of machinery. But as these illus-
trate no new principles, we refer the student
to the excellent manual of magnetism by
Daniel Davis, Boston, where the whole
subject will be found very ably discussed.
211. The Electro-magnetic Telegraph is
Fig. 181.
Fig. 182.
a contrivance
which very happily illustrates the application of abstract
209. What does fig. 182 show? 210. Who first observed electro-mag-
netic motions?
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132
ELECTRICITY.
scientific principles and discovery to the wants of society.
The inconceivably rapid passage of an electrical current over
a metallic conductor was discovered by Watson in 1747^and
this discovery gave the first hint of the possibility of using
electricity as a means of telegraphic communication. Nume-
rous attempts were made, very early after this discovery, to
construct a telegraph to be worked by ordinary electricity ; but
from difficulties inherent in the mode, these attempts were
attended with only very partial success. The discovery of
electro-magnetism by CErsted, in 1820, supplied the neces-
sary means of successful construction. Superior to all other
contrivances in the essential conditions of simplicity, in con-
struction and notation, is the beautiful contrivance patented by
Professor Morse in 1837. In the accompanying figure (183)
Fig. 183.
we have a view of the most essential parts of Morse's tele-
graphic register. A simple electro-magnet m m, with its
poles upward, receives its induced magnetism from a cur-
rent of electricity conducted by the wires W W from the
distant station. As soon as the circuit is completed, m m
becomes a magnet, and draws to its poles an armature or bar
of soft iron a on the lever I. The motion of this lever starts
a spring which sets in motion the clock arrangement c. This
clock machinery, in consequence of the weight attached to
211. Explain the principles oi' the electro-magnetic telegraph and itf
operations.
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ELECTRO-MAGNETISM. 133
ft, will, when once set in motion, continue to move. The
immediate object of the clock machinery is to draw forward
a narrow ribbon of paper pp in the direction of the arrows,
and to cause it to advance with a regular motion. The paper
ribbon passes by the end of the pen-lever l} in which re a
steel point *, that indents the paper whenever this end of
the lever is thrown upward by the attraction of the armature
a to the magnet m. If m m were constantly magnetized,
the mark made by the point s would be a continuous line.
But we can make and discharge an electro-magnet as often
and as fast as we please ; the instant, therefore, the circuit
WW is broken, m m ceases to be a magnet, and lets go the
iron armature a, when the point s of the lever falls, so as
no longer to mark the paper. The circuit being renewed,
the point marks again ; and this may be repeated as often
as the operator pleases. The length of time that the circuit
is closed will be exactly registered in the corresponding
length of the mark made by *. The completing of the cir-
cuit is performed by touching a spring on the operator'*
table, which establishes a metallic communication between
the poles of the battery. A touch will produce a dot, a con-
tinued pressure a long line, and intermitting repeated touches
a series of dots and short lines. These easily form an alpha-
bet. . To complete the arrangement, each operator must have
his own battery in connection with the register at the dis-
tant station. In practice, only one wire is used with each
register, the circuit being completed by connecting the other
pole of the battery with the moist earth by means of a buried
metallic plate and a wire. The remarkable observation that
the earth could be used in this manner as a part of the cir-
cuit, was made by Steinheil, in Germany, in 1837. Such is
a brief account of one of the most remarkable discoveries of
modern times. In Bain's telegraph, the circuit decomposes
a salt of iron, staining a paper with the marks of the con-
ductor, and no magnet is employed.
212. The telegraph has become an important auxiliary in
astronomical observations, by furnishing an exact means of
determining longitudes. For this purpose the principal
astronomical observatories in the United States are connected
by telegraphic wires, and such is the velocity of the electrical
wave that any communication made from one station will be
2& How is the telegraph auxiliary to astronomy?
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134 ELECTRICITY.
received at all the others at almost the same instant. The
velocity of the wave has been determined by the experiments
of the Coast Survey to be about 15,000 miles in a minute.
Wheatstone asserts that the wave of electricity moves as
rapidly at least as that of light. Other very ingenious and
important applications have been made of the telegraph for
regulating time-pieces and for signalizing fires. The city
of Boston is provided with such a system, a detailed descrip-
tion of which may be found in the American Journal of
Science for January, 1852.
One curious fact connected with the operation of the tele-
graph is the induction of atmospheric electricity upon tho
wires to such an extent as often to cause the machines at the
several stations to record the approach of a thunder-storm.
This induction occasions a serious inconvenience in working
the telegraph, not unattended with danger to the operators.
213. Professor Henry observed that when the current
from a single pair of plates was passed through a long con-
ducting wire, a vivid spark appeared at the instant of
breaking contact between the conductor and the battery ;
accompanied, also, by a feeble shock. A long conductor,
then, supplies the place of an increased number of plates in
a voltaic scries, and to some degree imparts the quality of
intensity to a current of quantity. A flat spiral of copper
ribbon, one hundred feet long, wound with cotton, and var-
nished, shows these effects well.
The magnetic needle indicates the
direction of the current, (fig. 184.)
The opposite sides of the spiral of
course produce opposite effects on
the needle. The magnetism pro-
| duced is, however, to be distin-
guished from the new effects ex-
cited by the passage of the feeble
Fie. 184. current through the coiled con-
ductor, on breaking contact, t. e.
the vivid spark and the shock. The latter is feeble with
100 feet of copper ribbon, and becomes more intense if tho
length of the conductor be increased, the battery remaining
the same ; but the sparks are diminished by lengthening
What other facts are mentioned regarding the telegraph J 213. What
was Henry's observation on the spiral ?
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ELECTRO-MAGNETISM.
135
the conductor beyond a certain point. The increase of in*
tensity in the shock is also limited by the increased resistance
or diminished conduction of the wire, which finally counter-
acts the influence of the increasing length of the current
On the other hand, if the battery power be increased, the
coil remaining the same, these actions diminish.
214. These effects Prof. Henry ascribed to the generation
of a secondary current at the moment of breaking contact.
This secondary current moves in a direction opposite to that
of the battery current. If a long coil of fine, insulated wire
be brought within a small distance of the flat spiral, this
new current will be detected in the second coil. The ar-
rangement used by Prof. Henry is seen in the annexed figure.
A small battery L is connected with the flat spiral of copper
ribbon A by wires from the battery cups Z and C. This
communication is broken at will, by drawing the end of one
of the battery wires Z over the rasp. When the coil of fine
wire W is in the position indicated in fig. 185, and the hands
Fig. 185.
grasp the conductors, a violent shock is felt as often as the
circuit is broken by the passage of the wire over the rasp.
When the coil W contains several thousand feet of wire, and
is brought near A, the shocks are too intense to be borne.
As this induction takes place through a distance of many
inches, we can, by placing the spiral A against a division
wall, or the door of a room, give shocks to a person in
another room, who grasps the conductors of the wire coil W,
and brings it near to the wall on the side opposite to A. A
screen or disc of metal introduced between the two coils will
cut off this inductive influence. But if it be slit by a cut
214. What were these currents called? How do they move? What
•f the spark and shock ?
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186
ELECTRICITY.
from the centre to the circumference, as a ft
i in fig. 186; the induction of an intense current
in W is the same as if no screen were present.
Fig. 186. Discs or screens of wood, glass, paper, or other
non-conductors, offer no impediment to this induction.
215. Induced Currents of the third, fourth, and fifth order.
— If the wires from W be connected with another flat spiral,
and it with a second coil of fine wire, and so on, (fig. 187,)
a series of currents will be induced in each alternation of
coils. The secondary intense current in B will induce a
quantity current in the second flat spiral C ; and a second
fine wire coil W will induce a tertiary intense current, and
so on. These currents have been carried to the ninth order,
Fig. 187.
decreasing each time in energy by every removal from the
original battery current. The polarity, or direction of these
secondary currents, alternates, commencing with the second-
ary. Thus the current of the battery is -(- J ana* the secondary
current is + 5 the current of the third order is — ; the cur-
rent of the fourth order is + > and the current of the fifth
order is — . These alternations are marked in the figure
above, and were also determined by Prof. Henry.
216. Compound Electro-magnetic Machine. — By combin-
ing the results just briefly enumerated, a great number of
ingenious electro-magnetic machines have been produced,
adapted to medical use, and illustrative of the induction of
magnetism and secondary currents. One of these, contrived
by Dr. Page, is seen in fig. 188. In this little machine, a
short coil of stout insulated copper wire forms a helix, within
which some straight soft-iron wires M are placed. The
215. To what degree have they been carried?
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ELECTRO-MA O N ETTSM.
137
battery current is
made to pass through
this stout wire, by
which means mag-
netism is induced in
the soft iron. The
conducting wires are
so arranged beneath
the board that the
glass cup C contain-
ing some mercury is
Fig. 188.
in connection with the battery. The bent wire W dips into
this mercury, and also by a branch into B, and when in the
position shown in the figure, the current from the battery
will flow uninterruptedly. As soon, however, as the battery
connection is completed, M becomes strongly magnetic, and
draws to itself a small ball of iron on the end of P; this
moves the whole wire P W and raises the point out of the
mercury C; as the wire leaves the mercury, a brilliant
spark is seen on its surface, the contact being thus broken
with the battery, M ceases to receive induced magnetism,
and the ball P being consequently no longer attracted to
M, the wire W falls by its gravity to the position in the
figure. This again establishes the battery connection, and
the same effects just described recur; thus the bent wire W
receives a vibratory motion, and at each vibration a brilliant
spark is seen at C, and M becomes magnetic. It remains
only to mention that the short quantity wire is surrounded
by a fine intensity wire, 2000 to 3000 feet long, having no
metallic connection with the battery or quantity wire, with
its ends terminating in two binding screws on the left of
the board. The fine wire receives a secondary induced cur-
rent like the coil W, (185,) which, if touched, produces the
most intense shocks at each vibration of the wire. These
shocks are graduated by withdrawing part or all of the soft-
iron wires M.
217. Magneto-Electricity. — As we have seen effects pro-
duced from galvanism which exactly resemble those of ordi-
nary machine electricity and the magnetic influence, so,
conversely, we might expect the production of electrical
effects from the magnet. The electrical current from a single
216. Explain the apparatus, fig. 188.
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138
ELECTRICITY
galvanic pair, w.e have seen, produces magnetism in a spiral
wire at right angles with its own course ; so the induction
of magnetism in soft iron from a permanent magnet, in like
manner, produces an electrical current at right angles to
itself in the wire coiled on the armature. This class of
phenomena was discovered by Faraday in 1831, and our
countryman, Mr. J. Saxton, soon contrived a machine very
similar to the one in fig. 189, called a magneto-electrical
Fig. 189.
machine. This consists of a powerful magnet S, secured to
a board, with its poles so situated that an armature, formed
of two large bundles of insulated copper wire W, wound on
soft-iron axes, may be revolved on an axis before its poles,
by the multiplying wheel M. A current of electricity is
thus induced in W, just as in the flat coils, the permanent
magnet here taking the place of the flat spiral. The cur-
rent excited in W is led off by conductors to the binding
screws p and n, the continuity of the current being broken
/^~£^ (in imitation of the rasp in 185) by a contrivance
f * pm at b on the axis, called a break-piece, (fig. 190,)
VI z J which is made by alternate ribs of metal c and
^11 ' ivory t, the current is broken by the ivory and
Fig. 190. renewed by the metal, and at every break, the
person whose hands grasp the conductors, secured to p
and n, feels a sharp shock, which may be graduated at
will by the rapidity of the revolutions of M, and by the
adjustment of the break b. A long and fine wire — say
217. What is magneto-electricity ? Explain fig. 189.
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THERMOELECTRICITY. 189
8000 feet of wire ^ of an :z*Sn in diameter — is required
to produce shocks and chemical decompositions. A shorter
and stouter wire, as 250 feet of wire y1^ or J$ inch in dia-
meter will produce no shock, but will deflagrate the metals
powerfully, and produce a secondary current of induction
in soft iron. We thus imitate in magnetism the effects
produced from a voltaic current, the short and stout
wire of the armature is the simple circuit of large plates;
the long and fine wire is like the compound circuit of smaller
plates.
Thermo-Electricity, or the Electrical Current excited
by Heat.
218. If two metals unlike in crystalline structure and
conducting power are united by solder, and the point of
their union is heated or cooled, an electrical
current will be excited, which will flow from
the heated point to the metal which is the
poorer conductor. Bismuth and antimony are
such metals, being bad conductors, and unlike
in crystalline structure. If two bars of these
metals are united, as in fig. 191, and the point
c is warmed by a lamp, a current will be set Fig. 191.
in motion, which will flow from b to a, as in the figure.
The compass- needle may be thus
affected, as by the voltaic current.
For this purpose two bars may be
mounted as in fig. 192, and their
junction being heated by a lamp,
the needle will swing, in conse-
quence of the electrical current
excited by the heat. When several Fig. 192.
such are joined, we have a greatly increased
effect, as in the thermo-electric pile in Melloni's
apparatus, (fig. 193.)
219. Thermo-electric effects are not confined
to metals, for they may be produced from other *lg# 193, ''
solids, and even from fluids j and a single metal, as an iron
wire, which has been twisted or bent abruptly, will originate
a thermo-electric current when the distorted part is greatly
218. What is thermo-electricity ? How doe* the current move ?
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140 ELECTRICITY.
heated. The rank of the principal metals in the thermo-
electric series is as follows, beginning with the positive : —
Bismuth, mercury, platinum, tin, lead, gold, silver, zinc,
iron, antimony. When the junction of any pair of these is
heated, the current passes from that which is highest to that
which is lowest in the list, the extremes affording the most
powerful combination.
If we pass a feeble current of electricity through a pair
of antimony and bismuth, the temperature of the system
rises, if the current passes from the former to the latter ;
but if from the bismuth to the antimony, cold is produced
in the compound bar. If the reduction of temperature is
slightly aided artificially, water contained in a cavity in one
of the bars may be frozen. Thus we see that as change of
temperature disturbs the electrical equilibrium, so conversely
the disturbance of the latter produces the former.
Animal Electricity.
220. The existence of free electricity in the animal body
is proved by the results of Aldiui and Matteucci. In some
animals we see a special apparatus
for the purpose of exciting at will
intense currents of electricity.
There are also such currents in all
animals. For example, when the
lumbar nerves of a frog, held in
the manner shown in fig. 194, are
touched to the tongue of an ox
lately killed, and at the same in-
stant the operator grasps with the
Mother hand, well wetted in salt
T water, an ear of the ox, a con-
vulsion of the frog's legs indicates
Fig. 194. the passage of an electric current.
221. The same delicate electroscope also shows similar
excitement when its pendulous ischiatic nerves touch the
human tongue, the toe of the frog being held between the
219. What range have these effects ? How is a fall of temperature ob-
served in a compound bar of antimony and bismuth ? 220. What is
animal electricity ? Explain the experiment in fig. 194. 221. How else
is the same fact shown ? How does the cunont oiroulate ?
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ANIMAL ELECTRICITY. 141
moistened thumb and finger of the experimenter. This is
what Donne* calls the musculocutaneous current; passing
from the external, or cutaneous, to the internal, or mucous,
covering of the body. This current may be de-
tected, as was shown by Aldini, in the frog's
legs above. For this purpose he prepared the
lower extremities of a vigorous frog, (fig. 195,) {
and, by bending up the leg, brought the muscles
of the thigh in contact with the lumbar nerves :
contractions immediately ensued. Thus it ap-
pears from experiments made by Matteucci, that
a current of positive electricity is always circu-
lating from the interior to the exterior of a
muscle, and that although the quantity is ex- Flg* 1W*
ceedingly small, yet by arranging a series of muscles, having
their exterior and interior surfaces alternately connected,
he produced sufficient elec-
tricity to cause decided
effects. By a series of half ^<
thighs of frogs, arranged as \
in fig. 196, he decomposed Fig. 196.
the iodid of potassium, deflected a galvanometer needle to
90°, and by a condenser caused the gold-leaves of an elec-
troscope to diverge. The irritable muscles of the
frog's legs form an electroscope 56,000 times more
delicate than the most delicate gold-leaf electro-
nic fcei\ Professor Matteucci's frog-galvanoscope
(fig. 197) is therefore far the most sensitive test
of electricity that can be employed. When the
pendulous nerve is touched simultaneously in the
places where electrical excitement is suspected,
the muscles in the tube are instantly convulsed.
222. The electrical eel of South America men-
tioned by Humboldt, and the torpedo — a flat fish
found on our own coast — are remarkable examples g# 197,
of those animals having a special electrical apparatus of
nervous matter and cellular tissue arranged in the manner
of the pile. The student is referred to the lectures of Pro-
What has Donne called it ? How is it shown in the legs of the frog
alone ? How does this current circulate ? How does fig. 196 prove it ?
What is the delicacy of the frog-galvanoscope ? 222. What animals have
a special electric apparatus ?
Digitized
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142 ELEOTRICTTT.
feasor Matteucoi on living beings for further details on this
very interesting subject. We can only add, that the shock
from these animals is sufficient to charge a Leyden jar, to
produce chemical decompositions, and to paralyze vigorous
animals.
The legs of the common grasshopper are, it is said,
equally sensitive electroscopes as those of the frog.
Electro- Chemical Decomposition.
223. By far the most interesting chemical result of
Volta's pile was the new power it placed in the hands of
chemists, of unfolding the secrets of combination, and of
assigning their relative positions to the several elements.
Indeed, the electro-chemical theory has been carried so far
by some chemists, that every chemical decomposition has
been referred to the play of electrical forces.
224. The decomposition of water is the finest possible
illustration of this power. Water is a compound of oxygen
and hydrogen gases, in the proportions of one measure of
the former to two of the latter. When two gold or platinum
wires are connected with the opposite ends of the battery,
and held a short distance asunder in a cup
of water, a train of gas-bubbles will be seen
rising from each and escaping at the surface.
With two glass tubes placed over the plati-
num poles, (fig. 198,) we can collect these
bubbles as they rise, and shall soon find that
the gas given off from the — plate is twice
the volume of that obtained from the +
plate. When the tubes are of the same size,
this difference of volume becomes at once evi-
dent to the eye. By examining these gases,
we shall find them, respectively, pure hydro-
Fig. 198. gen an(j pUre oxygen, in the exact proportion
of two volumes of the former to one of the latter. The
rapidity of the decomposition is greater when the water
is made a better conductor, by adding a few drops of
sulphuric acid.
223. What was the most interesting result of Volta's pile ? 224. Ho#
is water decomposed by it? Describe fig. 198.
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ELECTRO-CHEMICAL DECOMPOSITION.
148
If we employ a decomposing cell with
only one tube over the conductors, it will
be found that the gaseous contents will
explode by the electric spark or by a
lighted taper ; and if this is done over
water the perfection of the vacuum re-
sulting from the explosion will be seen
by the height of the column which rises
in the tube, (fig. 199.)
225. We learn from this most in-
structive experiment, that the voltaic
current has power to decompose chemi-
cal compounds, that this decomposition
takes place in definite proportions of
the constituents — and that these consti-
tuents appear invariably at opposite
poles of the battery. Fig. 199.
226. A decomposing cell interposed in the circuit will
give ub an esact account of the amount
of electricity flowing. Such an in-
strument has been called by Faraday
a voltameter^ (fig. 200.) It differs
from the common decomposing cell,
in having a ground-glass tube at top
bent twice, no as to deliver the accu-
mulating gases into a graduated air-
vessel, in which their volume is mea-
sured, A more simple form of the
apparatus is easily constructed, as in
figure 201, (page 144,) of two glass
tubes, two corks, and the conductors p p.
227. The experimental researches in electricity by Dr.
Faraday wbiob are the basis of modern science on
this subject, required the introduction of certain new
terms, some of which require explanation. The termi-
nal wires or conductors of a battery are often termed
the poles, as if they possessed some attractive power by
which they draw bodies to themselves, as a magnet attracts
iron. Faraday has shown that this notion is a mistake,
and that the terminal wires act merely as a path or door
225. What does this experiment teach? 226. What other cells are
named ? 227. What is said of Faraday's researches ? What did they re-
quire? What does he call the poles, and why?
Fig. 200.
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144 ELECTRICITY.
PQ to the currents, and he therefore calls them
electrodes, from electron and odos, a way.
The electrodes are any surfaces which convey
' an electric current into and out of a decom-
posable liquid. The term electrolysis, from
electron, and the Greek verb luo, to unloose,
is used to express decomposition ; and the
substances suffering decomposition are termed
electrolytes. Thus, the experiment mentioned
in the last section is a case of electrolysis, in
which water is the electrolyte. The elements
of an electrolyte are called ions, from the
. Jj Greek particle ion, going, since the elements
I <?o to the -f- or — electrode. The electrodes are
"^ ^ distinguished as the anode and the cathode,
from ana, upward, and odos, way, or the way
PO in which the sun rises ; and kata, downward,
Pig. 201. and odos, or the way in which the sun sets ;
the anode is -{-, and the cathode — . We will now briefly
consider the
228. Conditions of Electro- Chemical Decomposition. —
(1.) All compounds are not electrolytes, that is, they are
not directly decomposable by the voltaic current. Many
bodies, however, not themselves electrolytes, are decomposed
by a secondary action. Thus, nitric acid is decomposed in
the electrical circuit by the secondary action of the nas-
cent hydrogen, which, uniting with one equivalent of the
oxygen, again forms water and nitrous acid. Sulphuric
acid is not an electrolyte, while hydrochloric acid is ; and
the nascent chlorine from the latter attacks the -|- electrode,
if it be of gold. (2.) Electrolysis cannot happen unless
the fluid be a conductor of electricity ; and no solid body,
however good a conductor, has ever been thus decomposed.
A plate of ice, however thin, interposed between the elec-
trodes, will entirely prevent the passage of the power ; but
the electrolysis will proceed as soon as the least hole melts
in the ice, through which the power can pass. Fluidity is
therefore a very essential condition of electrolysis. The
fluidity may be that of heat, or of solution; thus, the
- Explain the terms electrode! electrolysis, and electrolyte. What are
ions ? 228. Are all compounds electrolytes ? Give examples. What
is the second condition of electrolysis ? Give examples.
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ELECTROCHEMICAL DECOMPOSITION. 145
chlorids of lead, silver, and tin are not electrolysed in a
solid state, but when fused they are decomposed with ease.
(3.) The ease of electro-chemical decomposition seems in
a good degree propoitioned to the conducting power of the
fluid. Thus, pure water is by no means a good conductor,
and its electrolysis is difficult ; but the addition to it of a
few drops of sulphuric acid, or of some other soluble con-
ductor, greatly promotes the ease with which it is decom-
posed. (4.) The amount of electrolysis is directly propor-
tioned to the quantity of electricity which passes the elec-
trodes. (5.) The binary compounds of the elements, as
a class, are the best electrolytes. Water and iodid of
potassium are instances; while sulphuric acid, which has
three equivalents of base to one of acid, is not an electro-
lyte. No two elements seem capable of forming more than
one electrolyte. (6.) Most of the salts are resolvable into
acid and base. Thus, sulphate of soda is resolved into sul-
phuric acid, which appears at the + electrode, and will
there redden a vegetable blue; and the soda which appears
at the — electrode will restore the previously reddened
blue; so that by reversing the direction of the current,
these striking effects are also reversed.
229. (7.) A single ton, as bromine, for instance, has no
disposition to pass to either of the electrodes, and the cur-
rent has no effect upon it. There can ' be no electrolysis
except when a separation of ions takes place, and the se-
parated elements go one to each electrode. (8.) There
is no such thing, in fact, (as has been often supposed,)
as an actual transfer of ions from one part of the fluid to
cither electrode. In the case of water, for example, oxygen
is given out on one side, and hydrogen on the other. In
order that this may be the case, there must be water be-
tween the electrodes. We cannot believe that the separa-
tion of the elements takes place
at the electrode where one ele-
ment is evolved, and that the
other travels over unseen to the
opposite electrode. We may, p. 202
(3.) To what is the ease of the electrolysis proportioned ? (4.) Tc
what is its amount owing ? (5.) What class of compounds are the best
electrolytes ? Give examples. (6.) What of salts ? Give examples.
229. (7.) What is said of a single ion? (8.) What of the transfer of
ions ? Give the explanation offered of the decomposition of water.
10
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146 ELECTRICITY.
however, conceive of water in its quiet state, as represented
by the diagram, (fig. 202,) each molecule being firmly
united by polar attractions (218) to every other, and that
the electrolytic force of the electric current has power to
disturb this polar equilibrium, each molecule being simi*
larly affected. In this case the electrolysis will proceed
from particle to particle through the whole chain of affini-
ties, decomposing and recomposing, until the ultimate parti-
cle on each side, having no
©
®T©1©M®
v^
©
polar force to neutralize
that eleo-
XXX XX X r\ 'xt> escaPes at that ele°-
^^J^J^J^Mo® trode which has a p°larifcy
F 2os opposite to itself. This
lg* " explanation may be better
understood, perhaps, by inspecting the second diagram, (fig.
203,) which represents a series of compound molecules of
water undergoing electrolysis, the H and 0 being eliminated
at the opposite extremities. The same explanation will be
found to serve for all other cases of electrolysis, both simple
and secondary.
230. (9.) A surface of water, and even of air, has been
shown capable of acting as an electrode, proving that the
contact of a metallic conductor with the decomposing fluid
is not essential. The discharge from a powerful electrical
machine was made to pass from a sharp point through
air to a pointed piece of litmus paper moistened with sul-
phate of soda, and then to a second piece of turmeric paper
similarly moistened. This discharge had power to effect a
true electrolysis ; the blue litmus was reddened by the sul-
phuric acid set free from the sulphate of soda, while the
yellow turmeric was turned brown by the alkaline soda from
the same salt.
231. (10.) Electrolysis takes place in a series of com*
pounds in the precise order of their equivalents. Thus, if
wine-glasses are arranged in a series, and in one is placed
sulphate of soda, in another acidulated water, in another
iodid of potassium, and in another hydrochloric acid, and if
the whole series be connected together by siphon tubes, or
moistened lampwick, passing from glass to glass, and a
230. (9.) What is said of electrolysis without metallic conductors?
Explain the experiment of the electrolysis of sulphate of soda by the
electrical machine 231. How does electrolysis occur in a series of com-
pounds?
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ELECTRO-CHEMICAL DECOMPOSITION. 147
powerful galvanic current be then passed through them,
electrolysis will occur in all, but unequally.
It has been proved by acccurate experiment, that the
decomposition which ensues is in exact proportion to the
equivalents of each substance. In other words, we may say
it requires one equivalent of electricity to decompose one
equivalent of an electrolyte formed from the union of an
equivalent of acid and another of base. Conversely, from
the fact that an equivalent of electricity is required to de-
compose any compound, it is proved that the opposite ele-
ments of this compound, in uniting, will disengage the same
equivalent of electricity.
232. (11.) The passage of a current within the cells of a
voltaic battery depends also upon the decomposition in each
cell, equally with that between the platinum electrodes.
The same phenomena which we notice in the decomposing
cell (224) take place also in each battery cell. Water is
decomposed, and the hydrogen is given off from the positive
plate, while the oxygen combines with the zinc, and thus
escapes detection. Therefore, no fluid not an electrolyte is
suitable to excite a battery. Acid water acts, for this pur-
pose, only by the decomposition of the water and oxydation '
of the zinc. The presence of the acid is useful only so far
as it combines with the oxyd of zinc constantly accumulating
on the zinc plate, which must be removed as fast as formed,
in order to keep up a steady flow of electricity.
233. The theories which have been proposed to account
for electro-chemical decomposition and the action of the
voltaic circuit, we cannot discuss here, any further than to
say that the chemical theory first proposed by Dr. Wollaston
is now generally accepted. Volta argued that the contact
of different metals was essential to the production of a cur-
rent. The researches of Faraday, however, in cod firming
the chemical view of Wollaston, have completely disproved
the contact theory. A very simple experiment by Faraday
illustrates this statement. A slip of amalgamated sheet
zinc bent at a right angle is hung in a glass of dilute acid;
on it is laid a folded piece of bibulous paper moistened with
In other words, what do we say ? Conversely, what ? 232. How
does a current pass in the cells of a battery ? What happens in each
cell ? What is requisite in the fluid used to excite a battery ? How
does acid water act in the battery? 233. What two theories have been
proposed to account for the electrical phenomena of electrolysis ? What
simple experiment disproves the contact theory ?
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148
ELECTRICITY.
iodid of potassum. A .platinum plate, with an
attached wire of the same metal, is now placed in
the acid water, but not in contact with the zinc;
the sharpened end of the wire is bent, so as to
touch the moistened paper, and very soon it is
discolored by a brown spot made by the freo
iodine, liberated from the electro-chemical de-
composition of the iodid of potassium, with which
the paper is moistened. There is no contact of
metals, and the current is excited only from the
Fig. 204, decomposition of the iodid out of the cell, and of
the water in it. A very strong argument in favor of the
chemical theory has been before mentioned, that the di-
rection of the current is always determined by the nature
of the chemical action — the metals most acted on being
always positive.
234. The electrotype, or deposition of metals from their
solution by the voltaic current, seems to have been suggested
by Daniell's battery. It has been remarked, that the cop-
per of the sulphate of copper in the outer cell of that battery
is deposited in a metallic state. The procuring of a pure
metal in a perfectly malleable state, by means of a current
of electricity, is a most important fact, and has given rise
to a new and valuable art, which has become wonderfully
extended in its applications. We thus accomplish, in fact,
a cold casting of copper, silver, gold, zinc, and many other
metals; and a new field of great extent has been thus
opened for the application of metallurgic
processes. The tinting of metals of various
hues by metallic oxyds*, and the coloring of
their surfaces by palladium, are among the
most surprising of its effects. The very
simple apparatus required to show these re-
sults experimentally, is represented in the
figure, (205.) It is nothing, in fact, but
a single cell of Daniell's battery. A^lass
tumbler S, a common lamp-chimney P,
with a bladder-skin tied over the lower end
and filled with dilute acid, is all the appara-
lg* ' tus required. A strong solution of sulphate
of copper is put in the tumbler, and a zinc rod Z in P,
234. What is the electrotype? Explain its uses.
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ELECTRO-CHEMICAL DECOMPOSITION. 149
the moulds, or casta, m m are seen suspended by wires
attached to the binding screw of Z. Thus arranged, the
copper solution is slowly decomposed, and the metal is
evenly and firmly deposited on m, m. A perfect reverse
copy of m is thus obtained in solid, malleable copper. The
back of m is protected by varnish, to prevent the ad-
hesion of the metallic copper to it. In this manner the
most elaborate and costly medals are easily multiplied, and
in the most accurate manner. In practice, casts are made
in fusible metal of the object to be copied, and the operation
is conducted in a separate cell, containing only the sulphate
of copper, one of Smee's batteries supplying the power.
The art is also now extensively applied to plating in gold
and silver from their solutions ; the metals thus deposited
adhering perfectly to the metallic surface on which they are
deposited, provided these be quite clean and bright
All the copper-plates of the charts of the Coast Survey are
reproduced by the electrotype — the originals are never used
in the press, but only the copies, and any required number
of these may be produced at small expense.
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150
PART H.— CHEMICAL PHILOSOPHY.
ELEMENTS AND THEIR LAWS OF COMBINATION.
235. The number of elements, (or simple substances,) as
now recognized, is sixty-two, forty-nine of which are metals
The elements are usually divided into metals and metalloids,
or non-metallic substances. This convenient distinction is
not strictly accurate, since there are several elements, as
tellurium, carbon, arsenic, silicium, and others, which seem
to possess an intermediate character. The term metalloid
is therefore preferable. Only fourteen of the elementary
bodies are of common occurrence, and of these the atmo
sphere, water, and the great bulk of the planet are com-
posed. The remainder are comparatively rare, and are known
only to the chemist. Of these, twenty-one, marked in the
table with an asterisk (*), will not be discussed in this work,
or will be very briefly considered, because of their great rarity,
and the difficulty of procuring the substances containing
them.
236. At common temperatures, and when set free from
combination, nearly all the elements are solids. Two, mer-
cury and bromine, are fluids, and five are gases, namely,
chlorine, fluorine, hydrogen, oxygen, and nitrogen. A few
only of the elements are found naturally in a free or un-
combined state, among which we may name oxygen, nitro-
gen, carbon, sulphur, and nine or ten metals. All the rest
exist in combination with each other, and so completely
disguised as to manifest none of their properties.
237. The names of the elements are arbitrary or conven-
tional, while the nomenclature of their compounds is sub-
ject to the strictest laws. Some of the elementary bodies
have been known from the remotest antiquity, and were in
common use long before the science of chemistry was heard
of. Thus several metals, as Copper, (Cwprwm,) Gold,
(Auruniy) Iron, (Ferrumf) Mercury, {Hydrargyrum^) Sil-
235. What is the number of elements? How divided ? What occupy
an intermediate position ? 236. What is the physical condition of th«
elements ? Which are fluid ? Which gaseous ? Which found uncoin-
bined ? 237. What of the names of elements ? Which have been long
known ?
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ELEMENTS— LAWS OP COMBINATION. 151
ver, (Argentum,) Lead, (Plumbum,) Tin, (Stannum,) have
long Deen known either oy the names we now give them, or
by those Latin terms of which our English names are trans-
lations. The alchemists named the metals after the various
planets. Thus, Gold was called Sol, the Sun ; Silver, Luna,
the Moon; Iron, Mars; Lead, Saturn; Tin, Jupiter; Quick-
silver, Mercury ; and Copper, Venus. Hence, formerly the
astronomical signs or symbols of these planets were employed
(o represent the names of these metals, and they are still in
use in some countries.
Several of the elements have been named from some
prominent or distinguishing physical property of color, taste,
or smell, which they possess : thus, Bromine is so called
from the Greek word bromos, fetor; Chlorine, from chloros,
green, in allusion to its greenish color; Chromium, from
chroma, color, because it makes highly-colored compounds,
as chrome-yellow; Glucinum, from glukus, sweet, from the
sweet taste of its salts ; Iodine, from ion, a violet, and eidos,
in the likeness of. Another class of names has been con-
trived from what was supposed to be the characteristic at-
tribute of the body in combination. Thus, Oxygen was so
named because many of its compounds are acids, from the
Greek, oocus, acid, and gennao, I produce. Hydrogen is
from hudor, water, and gennao, I produce.
238. It has been discovered that the elements, in com-
Dining among themselves, unite always in certain weights, in-
variable in each case, and supposed to have an immediate re-
lation to the atomic constitution of the substance. These
weights represent respectively the quantities in which the
elements unite with each other, and they are called equiva-
lent atomic weights or combining numbers. In the follow-
ing table, the equivalent or combining numbers of all the
elementary bodies are given in accordance with the latest
and best authorities. Because hydrogen enters into combi-
nation with other bodies in a smaller weight than any other
known element, it has generally been used in Great Britain
and in this country as the basis of the scale of equivalent
numbers. It is supposed also, by some good chemists, that
the numbers expressing the combining weights of all bodies
What of astronomical signs ? Whence such names as bromine, Hy-
drogen ? Iodine, Ac. ? 238. How do the elements unite ? What do the
weights represent ? What are they called ? Why is hydrogea unity ?
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152
ELEMENTS — LAWS OP COMBINATION*
would be found, on more accurate research, to be simple
multiples of the unit of hydrogen. If this view were cor-
rect, it would give us the great convenience of avoiding
fractional numbers. The latest investigations have so far
confirmed this idea, that in the present edition of this work
a largely increased number of elements stand with simple
numbers. Berzelius determined more atomic numbers than
any other chemist, and his labors have in most cases stood
the severest review, and deserve the everlasting gratitude of
chemists. Most chemists of continental Europe assume
oxygen as 100 ; therefore, to convert the numbers of the fol-
lowing table to the oxygen scale, multiply them by 12*5.
TABLE OF ELEMENTARY 8UB8TANCE8, WITH THEIR SYMBOLS ANI>
ATOMIC WEIGHTS OR EQUIVALENTS.
Name.
Aluminum
Antimony (Stibium)
Arsenic
Barium.
♦Beryllium (Glucinum)
Bismuth ,
Boron
Bromine
Cadmium
Calcium
Carbon
•Cerium
Chlorine
Chromium
Cobalt ,
•Cnlumbium (Tantalum)
Copper
•Didymium
•Erbium
Fluorine
Gold (Aurum)
Ilydrogen
Iodine
•Iridium
Iron
•Lantanium
Lend (I'lumbum)
Lithium
Magnesium
Manganese
Mercury
Name.
137 t
129- |
75- I
68-50
47
208*
109
Br
80-
Od
,56'
Ca
20*
C
6*
Ce
47*
CI
35.5C
Cr
26-7
Co
29-5
Cm,Ta
184-
Cu
31-7
D
E
Fl
19-
Au
197-
II
1-
I
127*
Ir
99-
Fe
28-
La
36-
Pb
103-5
Li
6-5
Mg
12-2
Mn
27-6
ne
100-
Nickol
Molybdenum
•Niobium
Nitrogon
•Noriura
•Osmium
Oxygen
•Palladium
•Pelopium
Phosphorus
Platinum
Potassium (Kalium)
•Rhodium
•Ruthenium
. Selenium
Silicium
I Silver (Argentum)
I So;lium (Natrium)
I Strontium
i Sulphur
I Tellurium
i *Terbium
i *Thorium
Tin (Stannum)
•Titanium.
•Tungsten(Wolframium)
Uranium
•Vanadium
•Yttrium.
Zinc
•Zirconium
Sym-
bol.
H =!•
Ni
29-6
Mo
40-
Nb
N
14-
No
Os
99-6
O
8-
Pd
53-3
Po
P
32-
Pt
98-7
K
39-2
It
62-2
Ku
62-2
Se
40-
Si
21-3
Ag
108-
Na
23-
Sr
44-
S
16-
Te
G4-
Tli
Th
59-6
Su
r>9-
Ti
20-
W
95-
U
CO-
V
68-6
Y
32-2
Zn
32-5
Zr
22-4
Combination by Weight.
239. The laws by which the elements unite to form com-
pounds, are included in the four following propositions : —
What of its multiple relations ? Who determined most atomic weights t
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COMBINATION BY WEIGHT. 153
1st. The law of definite proportions, or, a compound of
two or more elements, is always formed by the union of
certain definite and unalterable proportions of its constituent
elements.
2d. The law of multiple proportions, which requires that
when two bodies unite in more proportions than one, these
proportions bear some simple relation to each other.
3d. The law of equivalent proportions, according to which
when a body (A) unites with other bodies, (B, C, D, &c.,)
the proportions in which B, C, and D unite with A shall
represent in numbers the proportions in which they will
unite among themselves, in case such union takes place.
4th. The law of the combining numbers of compounds,
by which the combining proportion of a compound body is
the sum of the combining weights of its several elements.
240. These general laws of combination are subject to
some modifications, which will be explained as they arise.
The first of the laws above given is the result of chemical
analysis, and is proved by synthesis. Thus, from nine grains
of water we obtain eight grains of oxygen and one of hydro-
gen, and by the union of the like weights of these two sub-
stances we obtain nine grains of water. Constancy of com-
position is the essential feature of chemical compounds.
By the law of multiple proportions we learn that if a body
(A) unites with a body (B) in more proportions than one,
these proportions bear a simple relation to each other.
Thus, we may have the series of compounds A -f- B : A -f- 2B
: A -}- 3B : A -f- 4B : A -f- 5B, as in the case of nitrogen
and oxygen, between which this very series occurs, forming
five distinct compounds, in which one, two, three, four, and
five, parts by weight (atoms) of oxygen unite with one of
nitrogen. (2.) In place of this simple ratio we may have
one intermediate : thus, the expressions 2 A -(- 3B : 2A -j-
5B : 2A+7B represent a series of compounds which
are equal to the fractional ratios 1:1 J, 1:2}, 1 : 3 J.
241. As by chemical analysis the law of definite proportions
is established, so by the same direct experimental method do
We prove the law of equivalent proportions. Oxygen is an
element forming at least one definite compound with every
239. What is the 1st law of combination? The 2d? The 3d? The 4th?
240. Whence is law 1st derived ? Give an example ? What of the law of
multiple proportions? Give examples of the 2d modification? 241. How is
the law of equivalent proportions demonstrated ? What is said of oxygen ?
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154 ELEMENTS — LAWS OF COMBINATION.
other element known, except fluorine. These compounds are
termed oxyds, (246.) By analysis we find that water always
contains in 100 parts 11*11 parts of hydrogen and 88*89 parts
of oxygen. If we ask how much oxygen is proportional,
or equivalent to a unit of hydrogen, we state the simple
proportion 11*11 : 100 : : 88*89 : x in which x = 8, which
is therefore the equivalent of oxygen. In like manner, we
might go on making analyses of all the compounds of oxygen
until we had completed the whole list, when wo should have
a table of equivalents for all the elements, hydrogen being
unity. Thus,
8 parts of oxygen unite with •
10 parts of sulphur,
6" parts of carbon,
1 part of hydrogen,
35*5 parts of -chlorine,
100 parts of mercury,
28 parts of iron,
14 parts of nitrogen.
Of course, 16, 6, 1, 35.5, 100, 28, and 14, are respec-
tively the equivalents of sulphur, carbon, hydrogen, chlo-
rine, mercury, iron, and nitrogen. Chemical equivalent and
atomic weight have the same meaning in this work.
242. If any of those bodies unite to form compounds, the
union will always happen in quantities by weight exactly
proportional to those numbers. Thus, hydrogen (1) unites
with chlorine (35*5) to form chlorohydric or muriatic acid.
In 36*5 pounds, therefore, of this acid, there will be 1 pound
of hydrogen and 35*5 pounds of chlorine. If sulphur com-
bines with mercury, it will require 16 parts of sulphur and
100 parts of mercury, and there will be 116 parts of sul-
phuret formed ; or it may require 32 parts of sulphur to
100 parts of mercury, when we should have a bisulphuret. If
oxygen is assumed as the standard of comparison for atomic
weights, then, calling it 100, hydrogen will be 12*5, and all
the other elements will have numbers just twelve and a half
times as large as their equivalents on the hydrogen scale.
It follows, as a necessary result of this law of equivalent
proportions, that the combining numbers of a compound
should be the sum of the equivalents of its constituents.
Give the mode of determining atomic weights ? Give some examples ?
What is the meaning of chemical equivalent? Of atomic weight?
242. What is the relation among elements in combination? How is it
in chlorohydric acid ? In sulphurct of mercury ? What of the combining
numbers of compounds ?
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NOMENCLATURE AND SYMBOLS. 155
Chemical Nomenclature and Symbols.
243. It would have been a hopeless task for the strongest
memory to retain all the names of chemical compounds, if
they had — like the names of the elements — been bestowed
by the caprice of those who first discovered, or described
them. A committee of the French Academy, with Lavoi-
sier at their head, in 1787, settled the principles of chemi-
cal nomenclature, which endure to this day, although the
actual state of the science requires great changes in them.
All chemical compounds are made to derive their names from
one or more of their constituents. Before stating the rules
of nomenclature, we must define certain general terms of
common occurrence.
244. Bodies are divided into acids, bases, and salts. Salts
result from the union of acids with bases. By the voltaic pile
salts are decomposed (228 [6]) into acids and bases — the
acids go to the positive pole, the bases to the negative. We
therefore call the acid, in reference to electrical law, the
electro-negative constituent, and the base the electro-positive.
This is equally true of those compounds which render up
their elements in electrolysis as of salts which are simply
separated into acids and bases : e. g. common salt by elec-
trolysis yields chlorine, an electro-negative element, and
sodium, an electro-positive one. The former is an acid, the
latter a base.
Acids and bases are further distinguished, in that acids
redden the blue vegetable infusions, while bases restore the
colors which the acids have reddened. Some vegetable
colors, like syrup of violets, or tincture of dahlia or of pur-
ple cabbage, are made green by alkalies, and are reddened
by acids. If no change of this sort is indicated, the body is
said to be neutral.
245. When two elements unite, the product is called a
binary compound, from bis, twice; thus water, sulphuric
acid, oxyd of silver, and oxyd of iron, are binary compounds.
Compounds of binary combinations with each other, as of
243. What of the names of compounds ? Who settled the principles
of nomenclature ? How are the names divided ? 244. How are bodies
divided? How are salts formed ? What of the pile ? What does electro-
positive mean ? What electro-negative ? How of common salt ? How
are acids and bases further distinguished? What is neutrality ? 245.
What is a binary compound ?
Digitized^ VjOOQ IC
156 ELEMENTS — LAWS OF COMBINATION.
sulphuric acid with soda, forming sulphate of soda, or Glau-
ber's salts, are called ternary compounds, (from ter, thrice.)
Compounds of salts with each other, (as in the case of alum,
which is a compound of sulphate of potash and sulphate of
alumina,) are named quaternary compounds, from quatuor,
four.
246. The compounds of oxygen are called either oxyd$
or acids : thus, water is an oxyd of hydrogen ; and one of the
oxygen compounds of sulphur is called sulphuric acid.
The binary compounds of chlorine, bromine, iodine, fluo-
rine, and some other elements, which resemble oxygen in
their mode of combination, are also distinguished by the
same termination id or ide. Thus, chlorine forms chlorids;
bromine, bromids ; iodine, iodids ; and fluorine, fluorids.
The binary compounds of sulphur, selenium, phosphorus,
arsenic, and some others, receive usually the termination uret.
Thus we say sulphuret, seleniuret, phosphuret, &c., although
sulphid, selenid, phosphid, &c, are more in obedience to
the rules of the nomenclature.
247. In all cases, the name of the electro-negative con-
stituent of a compound rules the name of the genus of the
compound. Thus, chlorid of potassium, sulphuret of iron,
and sulphate of soda, all imply that the chlorine, sulphur, or
sulphuric acid, are the electro-negative constituents, and
that potassium, iron, and soda are the electro-positive ele-
ments in those compounds. The same rule holds in all the
salts also, however complex.
248. When the same element unites with oxygen in more
than one proportion, forming two or. more oxyds, then
these are distinguished as protoxyd, deutoxyd, tritoxyd, from
the Greek protos, first ) deuteros, second ; and tritos, third ;
corresponding to the first, second, and third degree of oxyda-
tion. The word hi (double) binoxyd is also used in place of
deutoxyd. The oxyd which contains the largest proportion
of oxygen with which the body is known to unite, is also called
the peroxyd, from the Latin, per, which is a particle of in-
tensity in that language. Thus, there are two oxyds of
hydrogen, the protoxyd (water) and the peroxyd. There
A ternary ? A quaternary ? 246. What of the oxygen compounds ?
How of the compounds of chlorine, Ac. ? How of sulphur, Ac. ? 247.
What of the electro-negative constituent? Give examples. 248. How
are the first, second, third, Ac, oxyds distinguished? What are hi-
noxyds ?
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NOMENCLATURE AND SYMBOLS. 157
are three oxyds of manganese: 1. The protoxyd; 2. The
deutoxyd; 3. The peroxyd of manganese. Some oxyds are
formed in the proportion of 2 to 8, or once and a half.
Such oxyds are distinguished by the term sesquioxyds, from
the numeral sesqui, (once and a half.) Certain inferior
oxyds are called suboxyds, as suboxyd of copper, Cu90.
249. The acid compounds of oxygen derive their names
by adding the terminations ous or ic with the word acid to
the electro-negative constituent. Thus, for the two acids of
sulphur we have sulphurous acid and sulphuric acid : the
first signifies the lowest, the second the highest oxygen
compounds of the substance known at the time when the
rules of the nomenclature were framed. As the progress of
science has made known other and intermediate compounds,
in order to bring them into the system, it was necessary to
employ the terms hypo and hyper, from hupo, under } and
huper, above. Thus, we have hyposulphurous and hyper-
sulphurous, for two acids of sulphur respectively under and
above sulphurous in their quantities of oxygen. The pre-
fix per has been added to signify a degree of oxydation
higher than that implied by ic. Thus, chloric acid was for
a long time the highest known degree of oxydation of
chlorine ) but now we have perchloric acid also. Peroxyd
mean 8 the highest oxyd known.
250. Sulphur, selenium, tellurium, arsenic, &c., and chlo-
rine, bromine, iodine, and fluorine, also form acid compounds
with hydrogen. These are named after the electro-negative
compounds, sulphydric, selenhydric, chlorohydric, bromohy-
dric, &c. Sulphuretted hydrogen, arseniuretted hydrogen,
ftc, are also used, as well as hydrochloric, hydrobromic,
&c. ; but the first named are more in accordance with the
principles of the nomenclature.
251. The salts (ternary compounds) are named in an
equally simple manner. The acid supplies the generic, the
base the specific name. Sulphate of soda, nitrate of potassa,
sulphite of soda, and nitrite of potassa, are respectively salts
of sulphuric, nitric, sulphurous, and nitrous acids. Thus,
What sesquioxyds ? Suboxyds ? 249. How are the aeid compound!
of oxygen named ? What of hypo and hyper ? What of the prefix per J
Give examples. 250. How are acid compounds of sulphur, Ac, with
hydrogen named? 251. How are salts named? What gives generic,
and what ipecifio names ? How do the acids change the termination!
out and ic ?
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158 ELEMENTS— LAWS OF COMBINATION^
in forming salts, the acids change the terminations ous and
icf into ite and ate.
When there are more oxyds of a base than one entering
into combination, the resulting salts are distinguished, for
example, as sulphate of the protoxyd of iron or sulphate of
the peroxyd.
252. Chemistry enjoys the peculiar advantages of possess*
ing a descriptive and defining nomenclature. Permanganate
of potassa is not a trivial name, but supposing that we now
saw it for the first time, we learn from its simple inspection
that the compound contains permanganic acid, and the base
potash ; and further, that the acid in question is the highest
oxygen compound of manganese known.
Convenient as the nomenclature of chemistry is, the pro-
gress of the science has made known so many and such
complex compounds, that it long since became necessary to
devise some simple mode of notation by which they might
be expressed, briefly and with certainty. Berzelius sup-
plied this requisite in the system of chemical symbols, by
which all chemical compounds may be described with mathe-
matical precision.
253. In the table of elementary bodies, (238,) the
" symbols" of the several elements will be found opposite
to their names. The symbols are merely the first letter of
each name, or the first two. By a happy thought, Berzelius
made each symbol represent not merely the substance for
which it stands, but one equivalent of each substance. Thus,
0 stands not for oxygen in general, but for one equivalent
of that element; or, hydrogen being unity, for the number
8. 0 and 8 are therefore interchangeable expressions, whfl*
O, O8, &c. represent 2 X 8 and 3 X 8, or 16 and 24.
Compounds are represented by using merely the symbols,
and sometimes uniting them by the sign of addition, (-f .)
Thus, water will be represented by HO, or one equivalent
of each element, 1 -f- 8 = 9, the combining number for
water. Protoxyd of lead is thus written PbO ; and PbO2 is
the peroxyd.
The co-efficient attached to a symbol signifies how many
When there are more oxyds than one, how is it ? Give examples.
252. What advantage of nomenclature has chemistry? Give an ex-
ample. What inconvenience was found? Who supplied the want?
253. What are symbols ? What do they express ? Give an instance
What of co-efficients ?
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— ....
.>
159
NOMENCLATURE AND SYMBOLS.
atoms of tiie element are concerned : thus, 0, O9, 0*, 0*, ()•, x
&G.y are respectively 1, 2, 3, 4, and 5 atoms of oxygen, which
may also be written 0& 08, &c, or 20, 30, 40, Ac. For-
mulse are expressions by which we recognize the constitution
of compounds; thus, sulphuric acid has the formula SO,, oxvd
of iron is FeO, and sulphate of protoxyd of iron is FeO+SOg,
oi one equivalent of that compound. Two equivalents
would be written 2(FeO+S08). If we write 2FeO+SO„
it means two atoms of protoxyd of iron, plus one of sul-
phuric acid. In chemical formulae, the electro-negative
element is placed last, the electro-positive is written first
Thus HO is water, not OH. When the sign plus is used
in a chemical expression, it usually signifies a union less
close than if a comma or no sign at all had been used.
Thus SO, HO + 2H0 signifies a hydrate of sulphuric acid
in which two atoms of water are loosely retained, while one
is in more close combination.
Water unites with bases 6> form hydrates, as the common
hydrate of potash or hydrate of lime, and also with acids
to form compounds analogous to salts. Thus, with sulphu-
ric acid, forming what in strictness should be called a sul-
phate of water ; but such cases are usually known as hydrated
acids. As 1, 2, or 3 atoms of water may unite with an acid,
so we have monohydrated, bihydrated, and terhydrated sul-
phuric or phosphoric acids.
254. Since chemical analysis only makes known to us
the number of constituents found in a compound, and the
mode in which these are arranged is undetermined, except
by theoretical considerations, it is becoming more the habit
0f chemists to write formulae expressing only the results of
analysis. Thus, acetic acid is written C4 H4 0^ since this
is the result of an analysis of this substance. In accord-
ance with some views it is written C4 H8 08+H0. Sul-
phuric acid, usually written S08 HO, is written, perhaps
more unexceptionably, S04 H. These two modes of expres-
sion are denominated rational and empirical formulae.
255. Professor Graham suggests what he calls antithetic
or polar formulae, which shall place all the electro-positive
elements of a compound in one line, and all the electro-
What are formulae ? Give an example. Which constituent is placed
first? What of sign-)-? Give an example. What of hydrates and
acids ? 254. What two modes of stating analytic results are here men*
tioned ? 255. What are antithetic or polar formulae ?
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160 ELEMENTS— LAWS OF COMBINATION.
negative in a line above them, like the numerators and de-
nominators of fractions. Thus, water will be ~, sulphuric
.,0. ,Li . , 00, 04
acid f, sulphate of soda m ff« or ^.
256. The symbols are sometimes abbreviated still farther,
to simplify the expression of very complex combinations.
This is done by expressing one equivalent of oxygen by a
dot, two, by two dots, &c. Thus, S signifies the same as S08,
(dry sulphuric acid.) Common crystallized alum is written
in full, thus,
Als08>3S08+KO,S08+24HO.
We can conveniently condense this long expression ; thus
Al S8+KS+24H.
The short line under the Al signifies two equivalents of the
base. Sulphur is in like manner signified by a comma;
thus, bisulphuret of iron, Fe,S9, may be more shortly
written Fe. Symbolic formulae have contributed very much
to the progress of the science, and are invaluable as a ready
means of comparing as well as expressing the composition
of compound bodies.
257. There is an interesting relation between the atomic
weights, the specific gravities, and the combining measures
or volumes of those elements which exist in the gaseous
state, or are capable of assuming it. One grain of hydro-
gen occupies 46*7 cubic inches, but the same bulk or volume
of chlorine weighs 35*5 grains, of nitrogen 14 grains, df
iodine 127*1 grains, of bromine 80 grains, and of oxygen
16 grains. These weights respectively represent the density
of the several gases compared with hydrogen as unity ; but
they are also identical with the atomic weights of the seve-
ral elements, except oxygen, which is double. We have
before seen (224) that two volumes of hydrogen and one
volume of oxygen are evolved in the electrolysis of water.
The volumes in which gaseous elements unite are therefore
as 1 : 1 or as 1 : 2, or some simple ratio. Sulphur has J
the volume of oxygen and mercury four times. The combin-
256. How are symbols abbreviated ? Illustrate by alum. 257. What
rotation is named between bodies in tbe gaseous state ? Give illustra-
tions of this. How do elements unite by volume ?
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EX*Atf8lON.
161
«og measure of oxygen being one volume, the combining
folume of hydrogen, nitrogen, chlorine, bromine, iodine,
and mercury, will be two volumes.
258. In the following table, hydrogen is taken as the
unit of combining measures, and we observe that where
the numbers in the second column are the same as the
equivalents, then a volume represents an equivalent; other-
wise some simple multiple of it. As with sulphur (16X6
=96) and oxygen, (2 X8=16.)
Gases and Vapors.
Specific Gravities.
Chemical Equivalents.
Air-1.
Hydrogen=l.
By volume.
By weight
Hydrogen
0*069
0-972
1-105
2-421
8-716
5-544
6-976
6-617
1-
14.
16-
35-50
12M
80-
100-
96-
100 or 1
100 or 1
50 or*
100 or 1
100 or 1
100 or 1
200 or 2
16
1-
14-
8-
35-50
80-
100-
16-
Nitrogen......
Oxygen........
Chlorine..*..,..,...
Iodine vapor
Bromine vapor
Mercury vapor.....
Sulphur vapor.....
259. The combining measure of compound gases is vari-
able, but they bear a simple and constant ratio to each
other ; and hence the density of a compound gas may often
be more accurately calculated from the known density of
its constituents, and its change of volume in combination,
than it can by direct experiment. A single example will
illustrate this. Water consists of 1 atom of each of its
constituents, represented by 1 volume of O and 2 vo-
lumes of H. These three volumes weigh 1105-6+69 -3
-|- 69 -3=1244 -2= two volumes of steam, one of which =
half this sum, or 622, the density of steam, air being unity.
From a comparison of the experimental results obtained by
chemists, it appears that there exists a very simple relation
between the combining measures of bodies in the gaseous
state, compound as well as simple. Of a few bodies the
combining measure is like that of oxygen, one volume ; of
& large number double that of oxygen, or two volumes;
of a still larger number four times that of oxygen, or four
volumes ; while combining measures of three and vix, or of
fractional portions of a volume, as one-third, are compara-
258. Illustrate this further from the table. 259. How in compound
gates ? What is the case with water? What relations are established ?
11
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162 ELEMENTS — LAWS OP COMBINATION.
lively rare. These results in regard to combining measures
were first obtained by Humboldt and Gay-Lussac, and have
afforded the most remarkable confirmation of the atomic
theory of Dalton.
260. Atomic volumes are those numbers which are ob-
tained by dividing the atomic weights of bodies by their
densities, and this whether we speak of simple or compound
bodies. In mineralogy, as shown by Dana, this relation is
often of great importance in determining the relations of
species.
Specific Heat of Atoms.
261. Specific heat has already been explained, (117.)
If in place of comparing equal weights of different bodies
together, we take them in atomic proportions, we shall find
the numbers representing the specific heat of lead, tin, zinc,
copper, nickel, iron, platinum, sulphur, and mercury, to be
identical ; while tellurium, arsenic, silver, and gold, although
equal to each other, will be twice that of the nine previous
bodies, and iodine and phosphorus will be four times as
much. The general conclusion drawn from these and other
similar facts is, that the atoms of all simple substances have
the same capacity for heat. The specific heat of a body
would thus afford the means of fixing its atomic weight.
There can be no doubt of the truth of this in numerous
cases, but experiments are still wanting to show it to be
universally true. Compound atoms have in some cases been
shown to have the same relations to heat as the simple.
This is true of many of the carbonates, and some sulphates.
Isomorphism and Dimorphism.
262. Isomorphism is identity of crystalline form, with
a difference of chemical constitution. Identity of crystal-
line form was formerly supposed to indicate an identity of
chemical composition. We now know that certain sub-
stances may replace each other in the constitution of com-
pounds, without changing their crystalline form. This
property is called isomorphism, and those basis which admit
of mutual substitution are termed isomorphous. Chemistry
Who first observed these relations ? 260. What are atomic volumes?
261. What of specific heat of atoms ? 262. What is isomorphism ?
Give examples.
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ISOMORPHISM AND DIMORPHISM. 163
furnishes us many examples of these isomorphous bodies.
Thus, alumina and peroxyd of iron replace each other in*
definitely. The carbonate of iron and carbonates of lime,
magnesia, and manganese, are also examples, as the common
sparry iron, (spathic iron,') which is a carbonate of iron, in
which a large portion of carbonate of lime sometimes exists
without producing any change of form in the mineral. Oxyd
of zinc and of magnesia, oxyd of copper, and protoxyd of
tron, also take the place each of the other in compounds,
without any alteration of crystalline form. When those
bodies unite with acids to form salts, the resulting com-
pounds have the same crystalline form, and, if they have the
same color, are not to be distinguished from each other by
the eye.
In double salts, like common alum, these relations are
also found. Sulphate of iron may take the place of sul-
phate of alumina in common alum, and no change of form
will occur ; and soda may, in like manner, replace the pot-
ash. In fact, all the similar compounds of isomorphous
bodies have a great resemblance to each other in general
appearance and chemical properties. The two bases in a
double salt are, however, never taken from the same group
of isomorphous bodies.
263. A knowledge of this law is of great importance to
the chemist,, and often enables him to explain, in a satis-
factory manner, apparent contradictions and anomalies, and
to decide many doubtful points. It is supposed that the
elements whose compounds are isomorphous, are themselves
isomorphous.
The following group of isomorphous bodies is given by
Professor Graham in his " Elements." 1st family : Chlo-
rine, Iodine, Bromine, Fluorine. 2d family : Sulphur,
Selenium, Tellurium. 3d family: Phosphorus, Arsenic,
Antimony. 4th family : Barium, Strontium, Lead. 5th
family : Silver, Sodium, Potassium, Ammonium. 6th fami-
ly: Magnesium, Manganese, Iron, Cobalt, Nickel, Zinc,
Copper, Cadmium, Aluminum, Chromium, Calcium, Hy-
drogen.
264. Dimorphism and Polymorphism. — Some substances
have two forms, under both of which they are found. Thus,
In what doable salts is it found ? 263. What does this law explain 1
What groups are given ? 264. What are dimorphism and polymorphism 1
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164 ELEMENTS— LA W8 OF COMBINATION.
common calc-spar (carbonate of lime) generally occurs io
rhombohedrons, (49, fig. 13,) but in arragonite (which is onlj
pure carbonate of lime) it is seen as a rhombic prismj
(46, fig. 37.)
Bin-iodid of mercury is another example of the same
kind; and in both these cases the change of form is effected
by heat Polymorphism is where more than two forms of
the same substance are known; as in titanic acid, of which
rutile, anatase, andbrookite are three distinct orystallographio
Chemical Affinity.
265. Chemical affinity, or the capability of chemical
union between bodies, is not possessed alike by all. Oyxgen
is the only element capable of forming chemical compounds
with all other elements. Carbon can unite with oxygen,
sulphur, hydrogen, and some other bodies, but no coin*
pound has been formed between it and gold, silver, fluorine,
aluminum, iodine, and bromine. It is, therefore, said to
have no affinity for those bodies, or no capability of union
with them. The power of union among bodies, or affinity,
is exceedingly different in degree, and is much affected by
many circumstances. Thus A may unite with B, forming
AB ; but if C had been present, A might have so much
more affinity for C than it has for B, as to unite with it,
forming AC, while B would remain unaffected. For exr
ample, sulphuric acid and soda unite to form Glauber's salts,
or sulphate of soda; but if soda and baryta had both been
present, and sulphuric acid were added, only the sulphate
gf baryta would be formed, and the soda would remain dis-
engaged, unless there was sulphuric acid enough to satisfy
both. This is what is sometimes called elective affinity, as
if the acid selected the baryta rather than the soda.
266. The more unlike, as a general thing, any two bodies
are in chemical properties, the stronger is their disposition
to unite. The metals, as a class, have very little disposition
to unite with each other. But they unite with oxygen,
chlorine, and sulphur, forming fixed and determinate com-
pounds. The alkalies, potash and soda, form no proper
265. What of chemical affinity ? What of oxygen ? What of carbon ?
What determines the union of A and B? How if C were present?
What is this sort of affinity called ? 266. What of the similarity of
bodies ? Illustrate by an example.
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CHEMICAL AFFINITY. 165
compound with each other, and their alkaline properties are
not altered hy such union. Sulphuric and nitric acid may
be mingled in any proportion, but no new compound is
formed, and the mixture is still acid. But if the potash
%nd soda respectively be added to nitric and sulphuric acid,
the result will be saltpetre, or nitrate of potash, and Glau-
ber's salts, or sulphate of soda, two salts having neither
alkaline nor acid properties.
267. Solution is the result of a feeble affinity, but one in
which the properties of the dissolved body are unaltered :
thus, sugar is dissolved in all proportions in water or weak
alcohol. Camphor is soluble in alcohol, but the addition
of water to the solution will, by engaging the alcohol, cause
the camphor to be thrown down. Gum is soluble in water,
but not in alcohol. We have already seen that the solu-,
tion of various salts in water would produce cold (124) from
the change of state in the body dissolved;
268. The circumstances which modify the action of
affinity are numerous, some of which we may briefly notice.
We have said (8) that chemical affinity existed only among
unlike particles, and at insensible distances. Intimate con-
tact among particles is, therefore, in the highest degree
necessary to promote chemical union. Any circumstance
which favors such contact will increase the activity of, or
disposition to, chemical combination. Solution brings par-
ticles near together, and leaves them free to move among
each other: substances in a state of solution have, there-
fore, an opportunity to unite, which they do not possess
when solid. Hence the old maxim, " Corpora non agunt
nisi sint soluta." Carbonate of soda and tartaric acid, foe
example, both in a dry state, remain unchanged; but the
addition of water will at once, by dissolving them, bring
about a union. Heat being, in fact, a most powerful means;
of solution; will often eause union to take place. Sand or:
silica will not unite with soda or potash by contact or aque-
ous solution, but if the mixture in proper proportions is.
strongly heated, union takes place and glass is formed.
Sulphur will not unite with cold iron, but if the iron be,
heated to rednesss, or the sulphur melted, a vigorous union
takes place, and a sulphuret of iron results. Cohesion is
destroyed by heat and solution, and substances in fine
267.. What of solution? 208. Name circumstances affecting affinity.
Digitized by VjOOQIC
166 ELEMENTS— LAW8 OP COMBINATION.
powder unite more readily than in masses of large sise.
Dry sal-ammoniac and dry lime, in fine powder, mingled
together, evolve ammonia. This is an interesting example
of chemical action, by mere contact of dry substances.
269. Bodies in the nascent state (as it is called) will
often unite, when under ordinary circumstances no affinity
is seen between them. Thus hydrogen and nitrogen gases,
under ordinary circumstances, do not unite if mingled in tho
same vessel ; but when these two gases are set free at the
same timej from the decomposition of some organic matter,
they readily unite, forming ammonia. The same is true of
carbon under the same circumstances, which will then unite
in a great variety of proportions with hydrogen and nitrogen,
although no such union can be effected among these bodies
under ordinary circumstances.
270. The quantity of matter, as well as the order and
condition in which substances may be presented to each
other, often exerts an important influence on the power of
affinity. Thus, vapor of water, when passed through a gun-
barrel heated to redness, will be decomposed, the oxygen
uniting with the iron, while the hydrogen escapes at the
other end of the tube. On the contrary, if dry hydrogen is
passed over oxyd of iron in a tube heated to redness, the
hydrogen unites with the oxygen of the oxyd of iron, leav-
ing metallic iron, while vapor of water escapes at the open
end of the tube. Other examples of this sort are observed,
where the play of affinities seems to be determined by the
preponderance of one sort of matter over another, or by the
peculiar condition of the resulting compounds, as regard*
insolubility, or the power of vaporization.
271. The presence of a third body often causes a union,
or the exertion of the force of affinity, when this third body
takes no part in the changes which happen. Thus, oxygen
and hydrogen gases may be mingled without any combina-
tion taking place between them, although a strong affinity
exists. If, however, a portion of platinum in a state of
very fine division (spongy platinum) be introduced into the
mixture, union takes place, sometimes slowly, but more
269. What of the nascent state ? Give an example. 270. What ol
quantity of matter ? What is catalysis ? Give examples.
• From nascent, being born, or in the moment of formation.
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CHEMICAL AFFINITY. 167
often with an explosion, the platinum being at the same
time heated to redness from the rapid condensation of the
gases which takes place in its pores. Advantage is taken
of this fact in constructing the common instrument for
lighting tapers by a stream of hydrogen falling on spongy
platinum. No change is suffered in this case by the plati-
num, which seems to act by its presence only. Berzelius
has proposed the term catalysis, from the Greek kata, by,
and luo9 to loosen, to express the peculiar power which
some bodies possess of aiding chemical changes by their
presence merely.
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168
PART m.— INORGANIC CHEMISTRY.
CLASSIFICATION OP ELEMENTS.
272. It is usual to divide elementary bodies into two great
groups, the non-metallic and metallic elements. This con-
venient arrangement is founded on characters which in a
general and popular sense are correct and easily distinguished,
but which fail in several cases to afford any accurate distinc-
tion. No one can doubt to which class, for example, gold
and sulphur should be respectively referred; but it is im-
possible to say why carbon and silicon are not as well entitled
to be classed in the same group with the metals as tellurium
and arsenic, if we except the single character of lustre.
We will discuss the first division of elementary bodies in
six classes, in the following order : —
}The only element which forms compounds
with all others, and the type of electro-ne-
gative bodies.
Four elements very similar in all their
. sensible properties, forming similar com-
. pounds with the metals, whose acid com-
. pounds with oxygen are also similar, and
. have the constitution expressed by RO,
J R04, RO„ ROt.
These stand in close relation with each
other, while their compounds with the me-
' tals are more similar to the oxyds of those
' metals than are the analogous compounds
of the second class. Their oxygen acids
have the formula RO* RO*
This group properly includes also arsenio
and antimony, which are, however, from
9. Nitrogen convenience, discussed elsewhere. The
10. Phosphorus . ' four form similar compounds with oxygen,
RO, ROt,' ROi, and peculiar gaseous com-
pounds with hydrogen, RH»
Class ii.
Class hi.
Class IV.
2. Chlorine..
3. Bromine..
4. Iodine....
5. Fluorine..
6. Sulphur...
7. Selenium.
S. Tellurium...
Class v.
Class vl
J 11 C bo 1 These three bodies are similar, non-vola-
19 (y\ ' I tile, combustible bases, and alike in form-
iz. biucon fing feeble acids with, oxygen. The formula
I "' 15oron J. RO, is adopted by some chemists.
This highly electro-positive body is un-
like any of the preceding, and has analogies
with the succeeding group of metals.
•j 14. Hydrogen. >
272. How are the elements divided ? What of the accuracy of this
division ? How many classes are named for 1st division ? Name the
1st class, the 2d, the 3d, the 4th. What other elements belong to this
group ? What is the formula of the hydrogen compounds of this group t
What is class 5 ? Class 6 ?
Digitized
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oxroEN. 1611
273 We will consider these several classes separately.
The compounds which each element forms with those before
it, will be taken up in order ; and we shall then be better
able to understand the relation of each element to its asso-
ciates in the same group. The several classes, too, will then
be better understood in the analogies which unite, and the
differences which separate them.
CLASS I.
OXYGEN.
Equivalent , 8. Symbol, 0. Density, 1*106.
274. Dr. Priestley discovered oxygen in 1774. It was
also rediscovered by Scheele, of Sweden, immediately after,
and without a knowledge Of Priestley's discovery. Before
this time, all gaseous bodies were considered to be only modes
of common air, and oxygen was first called vital air, and,
in allusion to the then existing theories, depMogisticated
air. It was the illustrious Lavoisier, author of the present
nomenclature of chemistry, who proposed the name oxygen,
(from oxus, acid, and gennao, I form.) Lavoisier had also
rediscovered oxygen in 1775. At that time it was supposed
that all acids contained oxygen.
Oxygen is the most widely diffused and important of the
elements. It forms over one-fifth part of the atmosphere
by weight, eight-ninths of the waters of the globe, and pro-
bably one-third part of its solid crust. It has also the widest
range of affinities of all known substances, and by its im-
mediate agency combustion and life are alone sustained.
275. Preparation. — Oxygen gas is procured by heating
the oxyds of lead, mercury, or of manganese, or the salts,
nitrate of potassa, chlorate of potassa, or nitrate of soda.
Chlorate of potassa is, however, the salt generally em-
ployed, as yielding a large volume of pure oxygen with a
gentle heat. This salt contains six equivalents of oxygen,
and parts with them all at a moderate heat, leaving a residue
of chlorid of potassium. Thusei05KO==ClK + 60. One
ounce of chlorate of potassa yields 543 cubio inches of pure
oxygen, or over a gallon and a half. The arrangement of
273. In what order are they discussed ? 274. Who discovered oxygen,
and when ? How were gases formerly considered ? Who named oxygen ?
Whence the name? What of the importance and dufusion of oxygen?
276. How is it prepared?
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170
NON-METALLIC ELEMENTS.
apparatus for this purpose is shown in fig. 206. A con*
veuient portion of chlorate of potassa is pulverized and mixed
with its own weight of
manganese, or better
with the black oxyd
of copper. The dry
mixture is placed in
the flask a of hard
glass, where it is
heated by the lamp
below. A bent tube
fitted to a by a cork,
conveys the gas to the
air-bell b, previously
Fig. 206. filled with water and
inverted in the water-trough. The heat of the lamp decom-
poses the salt, and pure oxygen is freely given off, displacing
the water in the air-jar. By aid of the oxyds of manganese
or copper the decomposition of the chlorate of potassa is
rendered gradual and safe. Without this precaution the
operation proceeds with almost ungovernable energy; the
whole volume of gas being given off almost at the same instant,
when the point of decomposition is reached. The metallic
oxyd seems to act by distributing the heat, and by the me-
chanical distribution of the salt: clean sand may be used
with nearly equal success. The glass may be protected from
fusion by a thin metallic cup c employed as a sand-bath.
276. When large
volumes of oxygen
gas are required, a
more economical
plan is to heat the
peroxyd of man-
ganese strongly in
an iron retort ar-
ranged in a rever-
beratory furnace,
(fig. 207.) One
pound of good oxyd
Fig. 207. of manganese will
Give the way by chlorate of potassium. Why is oxyd of manganese
used ? How does it act ? 276. What is the process by fig. 207 ?
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OXYGEN.
171
,-.
yield seven gallons of oxygen, with some carbonic acid. Thii
last is removed by passing the gas through t^e wash-bottlo
w containing solution of potash, which absorbe carbonic acid.
In this process Mn09 becomes MnO + 0; about twelve
per cent, of the weight of oxyd employed being obtained
as oxygen. Oxygen gas may also be procured from oxyd
of manganese by aid of strong sulphuric acid and a moderate
heat. The mixture is placed in a balloon d, (fig. 208,) and
heat applied.
Sulphate of
manganese is
formed, and
half the quan-
tity of oxygen
in the original
oxyd, or one
equivalent, is __y
given off. Car- ""
Sonic acid is
removed by
thepotoshso- B* So-
lution in w. Bichromate of potash may be substituted for
the oxyd of manganese in this case with good results. Both
should be in fine powder.
277. Properties and Experiments. — Oxygen, when pure,
is a transparent, colorless gas, which no degree of cold or
pressure has ever reduced to a liquid state. It is a q
little heavier than the atmosphere, its density being,
compared to air, as 1-1057 : 1 -000. One hundred cubic
inches of the dry gas weigh 34*19 grains. It is without
taste or smell. It is very slightly dissolved in water,
one hundred volumes of water dissolving only about
four and a half of the gas. Its most remarkable pro-
perty is the energy with which it supports combustion.
Any body which will burn in common air, burns with
greatly increased splendor in oxygen gas. A newly
extinguished candle or taper, (fig. 209, J which has the
least fire on the wick, will instantly be rekindled in
oxygen, and burn in it with great beauty. A quart FigTaw,
How is gas of this source purified ? What is the reaction of heat
on manganese ? How is O procured by sulphuric acid as in fig. 208 ?
277. What are the properties of O ? How does it act oq combustibles?
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172
NON-METALLIC ELEMENTS.
bifr 210,
of this gas in a narrow-mouthed bottle, will
easily relight a candle fifty times. A bit of
charcoal bark (fig. 210) with only a spark of
ignition on it, attached to a wire and lowered
into a jar of this gas, will burn with intense
brilliancy, producing carbonic acid. A steel
watch-spring dipped in melted sulphur and ig-
nited, when lowered into a jar of pure oxygen
.ltm, bursts into the most magnificent combus-
tion, (fig. 211.) The oxyd of iron
which is formed falls down in burn-
ing globules, like glowing meteors,
which fuse themselves into the glazed
surface of an earthen plate, although
covered with an inch of water. If,
as often happens, a motion of the
spring throws a globule of this fused
oxyd against the side of the glass
vessel, it melts itself into the sub*
stance of the glass, or, if that is thin,
goes through it. This is one of the
most brilliant and instructive expe-
Fig. 211. riments in chemistry. If the ori-»
fice at top is closed air-tight, and water is poured into the
plate, we shall find, as the experiment, proceeds, that the
water will rise in the jar as the gas is consumed. If we
could collect and weigh the globules of oxyd of iron, we
should find in them an increase of weight equal to the
weight of the oxygen consumed.
If the watch-spring or wire is coiled
into a helix, as in fig. 212, then the com-
bustion proceeds in a most beautiful
series of revolutions, greatly heightening,
the splendor of the experiment. These
experiments should be conducted in a.
dark room to have the full effect of their
brilliancy.
If the flame of a lamp, (Fig. 213,) is
supplied by a jet of oxygen, the tempe-
rature of combustion is so much elevated
Fig. 212.
Explain the experiments in figs. 210, 211, and 212.
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OXYGEN. 173
that a £latina wire may be fused in it* We
thus imitate the oxyhydrogen blow-pipe to
be described further on, (885,)
278. Oxygen, when inhaled, affects life by
quickening the circulation of the blood, and
causing an excitement, which, if continued,
would result in general inflammatory symp- " Fie. 213.
toms and death. In an atmosphere of pure
oxygen we would live too fast, exactly as combustion is
too rapid in an atmosphere of this gas. It exerts, how-
ever, no specific poisonous- influence, being, when used in
moderation, altogether salutary, and often resorted to, to
inflate the lungs of drowned persons, and not unfrequently
with the most beneficial results. The blood is constantly
brought into contact with the air in the lungs, and it is
the oxygen in the air which is the active agent in render-
ing it fit to sustain life. Pure oxygen is constantly supplied
to the atmosphere by the processes of vegetable life.
279. Ozone, the allotropic or double condition of oxygen.
When a stream of electrical sparks is passed through a tube
in which a current of dry pure oxygen is flowing, the gas
assumes new properties. The same result is obtained also
where water is electrolysed, (224,) when phosphorus slowly
consumes in a globe of moist air, or when a Leydeh battery
is discharged. In all these cases there is a peculiar odor,
perceived also after a powerful discharge of electricity from
the clouds. Hence the name ozone, from ozumi, to smell.
However this result may be obtained, it is observed that
oxygen in this condition, or air containing it, presents much
more powerful oxydizing powers than ordinary oxygen. It
will turn strips of white paper dipped in protosulphate of
manganese to brown, from the production of peroxyd of man-
ganese. It will decolorize solution of indigo as promptly
as nitric acid, and it bleaches even more powerfully than
chlorine. This body, Schonbein, its discoverer, regards now
as an allotropic condition of oxygen, (as suggested by Berze-
lius.) Its presence in the air is shown by the discoloration
of papers dipped in iodid of starch solution. It has been
argued, but on insufficient grounds, that this body in the
278. How is the lamp flame affected ? How does it act on life ? How
on the blood ? 279. What of ozone ? How obtained ? What its cha-
racters?
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174
NON-METALLIC ELEMENTS.
lir was a miasmatic agent. A few words will be in plac*
here, upon the
Management of Gases.
280. Pneumatic Troughs. — Gases not absorbed by water,
are always collected in
a vessel of water, called
a pneumatic trough.
Figure 214 shows a
small neat one, mado
of glass, proper for the
lecture-table ; but, for
general purposes, they
are usually made, like
the one below, (fig.
215,) of japanned cop-
per, of tin plate, or of
wood, to hold several
gallons of water. The
Fig. 214.
essential parts are the well W, in which the air-jars are
filled, and a shelf S,
covered with about an
inch of water. A
groove or channel d
is made in the shelf, to
allow the end of the
gas-pipe to dip under
the air-jar. If nothing
better is at hand, a
common wooden tub or
water-pail, with a per-
forated shelf and invert-
ed funnel, will answer for small operations. Learners are
sometimes puzzled to tell why the water stands in an air-
jar above the level of the cistern. A moment's thought,
however, on the principles of atmospheric pressure (27)
already explained, will make this clear. We must remem-
ber, too, that gases are only light fluids, and must be pour-
ed upward in water, by the same laws which require fluids
heavier than air to be poured downward.
281. To store large quantities of gases, capacious vessels
280. What is a pneumatic trough ? How are gases managed ? How
poured ? 281. How are they stored ?
Fig. 215.
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OXYGEN.
175
,-$.
of copper or tinned iron are used, which are called gas-
holders. These vessels are made frequently to hold 30 to
50 gallons. The simplest form is that of a large air-jar, pro-
vided with stopcocks at the top for the entrance and escape
of the gas, and contained in an exterior cylindrical vessel of
water. A more con-
venient gas-holder for
some purposes is that
s contrived by Mr. Pepys,
a view and section of
which are shown in the
annexed figures, (216
and 217.) It is a tight
cylinder of copper or
tin g, with a shallow
pan of the same metal,
supported above it by '
Fig. 21G. several props, two of Fi£- 2l7-
which are tubes with stopcocks, a b. Near the bottom is
a large orifice o, for receiving the gas. To use this instru-
ment, it is first filled with water by closing the lower orifice
a with a large cork, and opening all the upper ones
a b s. Water is then poured into the shallow pan ' p}
until it runs out at s, which is then closed; the remain-
der of the air escapes through b; when it is full, the
cocks a b are shut, and the lower orifice being then opened,
the water, sustained by the pressure of the air, cannot
escape except as it is driven out by the entrance of the gas
at o, from which it runs as fast as the gas enters. When
used, arrangements must be made to
provide for the water driven out by the
gas entering at o. The gas is obtained
for use by drawing it off from the orifice
* or b at the same time that the
shallow pan p is full of water, and the I
cock a open. The tube to which
this cock is attached goes nearly to the
bottom of the vessel. An air-jar is
easily* filled with gas from the holder
by placing it full of water in the upper
Fig. 218.
Explain figures 216 and 217.
Explain figure 21S.
How is gas drawn from the gas bolder I
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176 NON-METALLIC ELEMENTS.
pan, (see fig. 218,) over the orifice b; on turning the twc
stopcocks a by the gas issues from b and fills the jar, while
the water of the jar runs down the pipe a to supply the
place of the gas.
In collecting gas, the precaution should never b» neglected
of first allowing all the atmospheric air to escape from the
vessels, before any of the gas is saved for use.
Bags of vulcanized India-rubber cloth aro prepared by
the instrument-makers as gas-holders, which can be used
without the inconvenience of employing water. They are
filled by the flexible pipe p and stop-
cock c, (fig. 219,) which also serve for
the exit of the gas.
Gases which are absorbed by water
may be collected over mercury; the
' high price of mercury makes, however,
Fi 219 fckis an expensive method ; moreover,
some gases — as chlorine, for instance —
act chemically on the mercury. We may better collect the
absorbable gases in clean dry vessels, by displacement of
air, as is explained in the next section.
CLASS II.
CHLORINE.
Equivalent, 35-50. Symbol, CI. Density, 244.
282. History and Preparation. — This very remarkable
element was first noticed by Scheele, in 1774, while examin-
ing the action of chlorohydric acid on peroxyd of manga-
nese. For a long time it was believed to be a compound
body. It was called chlorine by Davy, who established its
elementary character.
It is easily obtained from chlorohydric acid HC1, by its
action upon pulverized oxyd of manganese, in an apparatus
similar to figure 220. The acid is poured in at pleasure by
the safety tube s, after the manganese has been made into
a paste with the first portions. The heat of a lamp or a
an of coals evolves the gas freely. It is rapidly absorbed
y cold water; but if the vessels are filled with water of
What of India-rubber bags? What of absorbable gases ? 282. When
and by whom was chlorine discovered ? How is it obtained ? How is it
collected?
/
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CHLORINE.
177
Fig. 220.
Fig. 221.
100° to 150° temperature, it is collected with little loss.
Any acid vapors are washed out in w. A strong solution of
common salt (brine) does not absorb chlorine, and may be
usefully employed in some cases to collect this gas in a small
porcelain or other trough. Owing to its great weight, it may
also be very conveniently collected by displacement of air
in dry vessels, using an apparatus like figure 221. The fluc-
tuations of the air are prevented by a bit of card-board with
a slit on one side, and the greenish color of the gas enables
the operator to see when the vessel is full. The vessels
must have glass stoppers or covers of glass ground tight;
in such, the gas may be preserved at pleasure. The opera-
tion should be performed in a well-ventilated apartment,
to avoid injury from the corrosive and irritating gas.
283. In this process the affinities are between the man-
ganese, for one equivalent of the chlorine in the acid, form-
ing chlorid of manganese, and between the oxygen of the
manganese and the hydrogen of the acid, forming water
The following symbols will render this more clear : we take
MnO, and 2HC1, and obtain MnCl, 2HO, and CI.
How by figure 221 ? What precaution is advised? 283. What art
the affinities in this process? Give the equation.
12
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178
NON-METALLIO ILEMENTS.
The last equivalent of chlorine, having nothing to detain
it, is given off.
Pure chlorine is also easily obtained by acting on one
part of powdered bichromate of potash, in a small retort,
with six parts of strong hydrochloric acid. A gentle lamp-
heat is required to begin the process, which then goes on
without further application of heat, yielding abundance of
gas.
Dry chlorine is
obtained by using
an apparatus, figure
222, attached to
the evolution flask
fig. 220 by o} any
acid vapors are
washed out in the
bottle w, and all
moisture is removed
by the chlorid of
Fig. 222. calcium tube a b, the
dry gas being collected by displacement in /.
284. Properties. — Chlorine is a greenish-yellow gas,
(whence its name, from chloros, green,) with a powerful and
suffocating odor. It is wholly irrespirable and poisonous.
Even when much diluted with air, it produces the most
annoying irritation of the throat, with stricture of the
chest, and a severe cough, which continues for hours, with
the discharge of much thick mucus. The
attempt to breathe the undiluted gas would be
fatal ; yet, in a very small quantity, and dis-
solved in water, it is used with benefit by pa-
tients suffering under pulmonary consumption.
For this purpose an inhalation apparatus is
used, like fig. 223. The mouth is applied at
o, the air enters at a, and, passing through the
dilute solution, becomes more or less charged
with chlorine. Cold water recently boiled ab-
sorbs about twice its bulk of chlorine gas,
Fig. 223. acquiring its color and characteristic pro-
perties. This solution is much used in the laboratory in
How is it obtained dry ? 284. What are its properties ? How does it
Affect respiration ? How is it safely inhaled ?
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id i
CHLORINE. 179
preference to the gas. It should be preserved in a blue
bottle, or in one covered by black paper, to avoid decompo-
sition, (228.) The moist gas exposed to a cold of 32° yields
beautiful yellow crystals, which are a definite compound
of one equivalent of chlorine and ten of water, (C1,10HO.)
Tf these crystals are hermetically sealed i
up in a glass tube, (fig. 224,) they will,
on melting, exert a pressure of five atmo-
spheres, so as to liquefy a portion of the
gas, which is distinctly seen as a yellow Fig- 224-
fluid, of density 1*33, not miscible with the water which is
present. It does not solidify at zero. Chlorine is one of
the heaviest of the gases, its density being 2-44, and 100
cubic inches weighing 76*5 grains.
285. Chlorine solution readily dissolves gold-leaf, forming
chlorid of gold : silver solution produces in it a dense pre-
cipitate of chlorid of silver, which ammonia re-
dissolves. A rod a, (fig. 225,) moistened in
ammonia water, and held over chlorine solution,
produces a dense cloud of chlorid of ammonium.
A crystal of green vitriol dropped into a test-
tube containing chlorine water, gives a dark so-
lution at bottom of perchlorid of iron. Fi«- 225-
286. The bleaching power of chlorine is one of its most
remarkable and valuable properties. The solution of chlo-
rine immediately discharges the color of calico rags or of
writing-ink. The moist gas does the same, but the dry gas
does not bleach. Chlorine is evolved in the arts from a
mixture of salt, sulphuric acid, and manganese, for the
bleaching of paper and rags, and of all manner of cotton or
linen stuffs. It does not bleach woollens, nor printers' ink,
probably because of its indifference to carbon, which forms
the basis of printers, ink. The bleaching power is probably
due to its affinity for hydrogen.
287. Chlorine spontaneously inflames- phosphorus, and
powdered metallic arsenic, or antimony, forming chlorids of
those substances. A rag or bit of paper, wet with oil of
turpentine and held in a bottle of chlorine, is inflamed, and
What of its solution? How crystallized? How liquefied? How
donee? 285. What are tests for chlorine? 286. What valuable pro-
perty of CI is named ? How if dry gas is used ? How is it evolved in
the arts ? What exceptions to its bleaching ? Whence this property J
287. How does CI act on phosphorus, Ac. ? How on oils ?
Digitized
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180 NON-METALLIC ELEMENTS.
the interior of the vessel is coated with a bril-
liant black varnish of carbon, derived from the
oil. A candle lowered into a vessel of chlorine,
(fig. 226,) is slowly extinguished, with the escape
of a dense volume of smoke. In these cases,
the action is between the chlorine and the hydro-
gen of the organic substances. The disinfection
of offensive apartments, sewers, and other like
Fig. 226. pjjuj^ jS rapidly accomplished by chlorine and
the " bleaching powders."
288. Double Condition, or AUotropism of Chlorine. —
Chlorine exists both in an active and a passive state.
The first is its condition as ordinarily known, when pre-
pared in daylight. If an aqueous solution of chlorine
be prepared as before mentioned, in recently boiled water,
and a part of it be exposed in an inverted bulb to the
direct rays of the sun, or a strong daylight, while another
portion, as soon as prepared, without exposure to light, is
set aside in a dark closet, and in a similar vessel, we shall
find them very differently affected. That which was in the
dark will have undergone no change, while that in
the sunlight will have suffered decomposition ; a
notable quantity of nearly pure oxygen will have
collected in the bulb, as shown in fig. 227, and
chlorohydric acid will have been formed in the fluid,
from the union of the chlorine and the hydrogen of
the water, whose oxygen is set free. The rapidity
Fig. 227. 0f tbjs decomposition of water by the chlorine, de-
pends on the intensity of the sun's rays, and the tempera-
ture, and being once begun, it continues afterward even in
the dark. The indigo rays (76) are chiefly instrumental in
producing this effect. (Draper.)
Compounds of Chlorine with Oxygen.
289. Chlorine and oxygen have no disposition to unite,
under any circumstances, directly; but numerous com-
pounds of these two elements are produced indirectly, of
which we tabulate five, as follows : —
How on a candle ? Whence this peculiarity? What of disinfection f
28S. How does light affect chlorine ? Illustrate by fig. 227. , What ray
effects this ?
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CHLORINE.
181
Symbol.
Hypochhrous acid CIO
Chlorous acid CIO.
Hypochlorio acid, (peroxyd of chlorine,) C104
Chloric acid CIO.
Hyperchloric acid , C10t
As the most simple method, we commence with —
290. Chloric Acid j (C105). — This most important com-
pound of chlorine and oxygen is formed when a current of
chlorine is pasaed through a solution of potash, to saturation.
On evaporating this solution, flat tabular crystals of a white
salt are gradually formed, which are chlorate of potassa,
while chlorid of potassium remains in the solution. The
reaction is between 6 equivalents of chlorine and 6 of
potassa, forming 5 of chlorid of potassium and I of chlorate
of potassa; thus, 6C1+6K0=5KC1+K0,C105. Chloric
acid Is obtained separate with some difficulty, by decom-
posing a solution of chlorate of baryta by the requisite
amount of sulphuric acid, and gradually evaporating the
filtered liquid to a syrup. In this state its affinity for all
combustible matter is so great, that it cannot be kept in
contact with any substance containing carbon or hydrogen.
Paper moistened by it takes fire as it is dried. The chlo-
rates are recognized by their powerful action on combustible
matter, by yielding pure oxygen when heated, and by
giving out the yellow chlorous acid when treated with
sulphuric acid.
291. HypocKLorous Acid, (CIO.) — This acid gas is ob-
tained when a current of chlorine traverses a weak solution
of potassa, when, if cold, no chlorate of potassa is formed,
but a solution having most remarkable bleaching powers.
It contains both chlorid of potassium
and hypochlorite of potassa ; thus,
2K0-|-2C1=K0,C10+KC1. It is ob-
tained also by the agitation of chlorine
with red oxyd of mercury, or better by
passing dry chlorine over red oxyd of
mercury, contained, as in fig. 228, in a
horizontal tube 6, (shown only in part,)
and condensing the evolved gas CIO in Fig. 228.
289. Name the compounds of CI and 0. What arc their formulas?
290. What is chloric acid? Ilow formed? What the reaction? What
character has chloric acid ? What of its salts ? 291. What is hypo-
valorous acid ? How obtained ? Give the reaction. Explain its produc-
tion by fig. 227.
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182
NON-METALLIC ELEMENTS.
the U tube, refrigerated by means of ice and salt in the
outer vessel. Chlorid of mercury is formed, and oxyd
of chlorine CIO. Hypochlorous acid is a light-yellow
gas, much resembling chlorine; condensed, it is a reddish-
yellow corrosive liquid, boiling at 68°, and sparingly
soluble in water. The vapor detonates with a hot iron : water
absorbs 200 times its volume of it, and gains a beautiful
yellow color and powerful bleaching properties. Its aqueous
solution is very unstable, being decomposed by light, and
even by agitation with irregular bodies, as broken glass.
Hypochlorous acid is one of the most powerful oxydizing
agents known, raising sulphur and phosphorus to their
highest state of oxydation — a result which only strong
nitric acid can accomplish. It is formed from two volumes
of chlorine and one of oxygen condensed into two volumes.
Thus,
2 volumes of chlorine weigh 4*880
1 " oxygen " 1-105
5985 -5-2 = 2-992
while experiment gives us 2-977 for the density of this sub-
stance. The euchlorine of Davy is a mixture of chlorine
and chloro-chlorous acid, and not a protoxyd of chlorine, as
was supposed. It is obtained when chlorohydric acid acts
on chlorate of potassa, is a greenish-yellow gas, darker than
chlorine, of a very pungent and persistent odor. It explodes
with a hot iron.
292. Chlorous, hy-
pochloric, and jper-
chloric acids are all
procured from the'
decomposition of
chloric acid. When
fused chlorate of
potassa is acted on
by sulphuric acid,
in the vessel b, (fig.
229,) a very explo-
sive, yellow gas
Fig. 229. collects in a. This
What ore its characters? What is its volume, constitution, and den-
sity ? What is euchlorine ? What of chlorous and hyperchlorous acids ?
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BROMINE. 188
experiment demands great precautions to avoid accident.
The vessel 6 may be secured by setting it into an outer
vessel of warm water. The gas explodes by a warm iron, by
pressure, and sometimes without any apparent cause.
293. If strong sulphuric acid is poured upon a small
quantity of crystals of chlorate of potash in a wine glass, a
violent crackling is heard, and the glass is soon filled with
the heavy yellow vapors of the chlorous acid gas, which at
once inflame a rag held over it wet with turpentine, with a
smart explosion. If chlorate of potash is mixed with sugar,
(both separately pulverized and mingled with caution,) a drop
of sulphuric acid will inflame the mixture with a brilliant com-
bustion. Phosphorus burns spontaneously in chlorous acid
gas : if some small fragments of phosphorus are added to a
glass of water at the bottom of which a few crystals of
chlorate of potash have been placed, (fig. 230,)
and sulphuric acid is introduced by means of a
long-tubed funnel to the bottom of the vessel,
the salt is decomposed, and the phosphorus
flashes under water in the chlorous acid which
is set at liberty. Fig. 230.
BROMINE.
Equivalent) 80. Symbol, Br. Density, in vapor, 5*39.
294. History. — This element was discovered in 1826, by
M. Balard, in the mother-liquor, or residue of the evapora-
tion of sea-water, and by him named from its offensive odor,
(bromos, bad odor.) It is widely diffused in nature, exist-
ing in minute quantities in combination with various bases
in the salt-water of the ocean, of the Dead Sea, and of
nearly all salt-springs. It is also found in a few minerals.
The salines of our Western States are many of them rich
in bromids. It has been largely prepared at Freeport,
Pennsylvania, on the Ohio, for use in pharmacy.
295. Bromine is a dense red fluid, exhaling at common
temperatures a deep reddish-brown vapor. It is one of the
heaviest non-metallic fluids known, its density being from
2*97 to 3 187. Sulphuric acid floats on its surface, and is
What precaution is given ? 293. What of sulphurio acid on chlorate
of potassa ? What is the action on phosphorus ? 294. Give the history
of bromine Where is it found ? 295. Give its characters.
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184 NON-METALLIC ELEMENTS.
used to prevent its evaporation. At zero it freezes into a
brittle solid. It boils at 116-5°. A few drops in a large
8ask will fill the whole vessel, when slightly warmed, with
blood-red vapors, which have a density of 5*39. It is a
non-conductor of electricity, and huffers no change of pro-
perties from heat or electricity. It dissolves slightly in
water, forming a bleaching solution ; and at 32°, if left in
contact with water, it forms a crystalline hydrate with it, of
a red bronze color, analogous to the hydrate of chlorine. It
is a corrosive and deadly poison, disorganizing organic struc-
tures with great energy. One drop on the beak of a bird
Produced instant death. It has even been used for suicide,
ts odor resembles chlorine, but is more offensive and per-
sistent. It has bleaching properties. In a word, bromine
in all its properties and combinations, has the greatest ana-
logy to chlorine, but is less energetic in its affinities, being
displaced by chlorine from its combinations.
Bromine acts with explosive violence on phosphorus, po*
tassium, antimony, and other similar substances, forming
bromids.
296. Bromine is used in photography, and its compounds
also in medicine. It is detected in the mother-liquor of
salt-water by chlorine gas, or solution of chlorine, which
sets it free, when it is recognized by its peculiar color.
Ether added to this solution takes up the liberated bromine
on agitation, and floats on the surface in a reddish-brown
stratum. It is prepared in the arts by distilling a mixture
of bromid of sodium, manganese, and dilute sulphuric acid,
and collcpting the product in a cold receiver.
Bromic acid Br05 is similar in all its reactions to chloric
acid, and forms salts with alkaline bases, called broraates.
The chloride of bromine BrCls is soluble in water and de-
composed by alkalies.
IODINE.
Equivalent y 127. Symbol, I. Density in vapor, 8*7.
297. History. — Like chlorine and bromine, this substance
has its origin in the sea, being secreted by nearly all sea-
weeds from the waters of the ocean. It was discovered in
What smell has it ? How does it act on combustibles ? 296. How
used ? How detected? What compounds does it form ? 297. What if
llie history of iodine?
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IODINE. 185
1811, by M. Courtois, of Paris, in the kelp, or ashes of sea-
weeds. The common bladder sea-weed, (fucus vesiculosa*,)
and many other sea-weeds of our own coasts, abound in salts
of iodine. It has been found in mineral springs associated
with bromine, but less abundantly, and also in one or two
minerals. In the arts its chief uses are for the photographic
pictures, and in the process of dyeing. In medicine it is
of great value, in glandular and other diseases.
298. Preparation.— :Kelp is treated with water, which
washes out all the soluble salts, and the filtered solution is
evaporated until nearly all tho carbonate of soda and other
saline matters have crystallized out. The remaining liquor,
which contains the iodine, as iodid of magnesium, &o., is
mixed with successive portions of sulphuric acid in a leaden
retort, and after standing some days to allow the sulphu-
retted hydrogen, &c, to escape, peroxyd of manganese is
added, and the whole gently heated. Iodine distils over in
a purple vapor, and is condensed in a receiver, or in a series
of two-necked globes.
299. Properties. — Iodine crystallizes in brilliant blue-
black scales of a metallic lustre, somewhat resembling plum-
bago. When slowly cooled from a state of dense vapor in
a glass-tube hermetically sealed, it crystallizes in acute octa-
hedrons with a rhombic base, (46.) The density of iodine
is 4*95, it melts at 235°, and boils at 247°, forming a superb
violet vapor of unequalled beauty; (hence its name, lodes, like
a violet.) For this purpose a few grains of it may be vola-
tilized in a bolt-head, or from a hot surface under a bell, as
in fig. 231, when on cooling it is deposited
in brilliant crystals lining the glass. It
assumes the sphreoidal state in a red-hot
crucible, forming a splendid experiment,
(131.) It is almost insoluble, one part dis-
solving in 7000 parts of water. Alcohol
___^^_. dissolves it largely, forming tincture of
"T!- T^"^ iodine. Sal-ammoniac, nitrate of ammonia,
and soluble iodids also dissolve it. It tem-
porarily stains the skin deep brown, and its odor reminds us
somewhat of chlorine.
300. Chlorine and bromine both decompose the com-
In what is it found ? How prepared ? 299. What are its characters?
What of its vapor ? How soluble ? What dissolves it?
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186 NON-METALLIC ELEMENTS.
pounds of iodine. Iodine is an energetic poison. Iodine
forms a beautiful deep-blue compound with a cold solution
of common starch. By this test a millionth part of iodine
can be detected. In combination it is detected by the same
agent, if a little nitric acid or chlorine water is previously
added to the fluid supposed to contain an iodid, whereby
the iodine is set free. Acetate of lead added to solutions of
salts of iodine produces a yellow crystalline precipitate. The
iodid of potassium is the salt most familiarly known of all
the iodine compounds, and is the usual form in which this
substance is administered medicinally.
Compounds of Iodine with Oxygen.
301. Iodine unites with oxygen, forming hypoiodic, iodic,
and hyperiodic acids. Their constitution is seen in the fol-
lowing formulas :
Hypoiodic acid I04
Iodic acid 10,
Hyperiodic acid IOi
These acids are analogous to the hypochloric, chloric, and
perchloric acids. Iodic acid is formed by the action of
strong nitric acid on iodine, and subsequent evaporation, to
expel the free nitric acid remaining. It is a very soluble
substance, and crystallizes in six-sided tables. Chlorine
unites with iodine, forming two, and possibly three distinct
chlorids, (IC1, IC18, and IC15.) These are formed by the
direct action of chlorine on dry iodine. There are also bro-
mids of iodine of uncertain composition.
FLUORINE.
Equivalent, 19. Symbol, F. Density, (hypothetical,) 1-292
302. This element is known entirely by its compounds
Its remarkable energy of combination with other elements,
and especially with silicon, which is a constituent of all
glass, has rendered its isolation very difficult. It is a yel-
lowish-brown gas, having the smell and bleaching proper-
ties of chlorine. It does not act on glass, (as its compound
with hydrogen does,) but unites directly with gold. Its
specific gravity is 1-292.
Fluorine forms no compound with oxygen, and probably
300. Give tests for iodine. Give its oxygen compounds ? 302. What
vf fluorine ? Why is it difficult to isolate ?
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SULPHUR. 187
holds a place intermediate between oxygen and chlorine.
Its most remarkable compound, fluohydric acid, we shall
mention in the section on hydrogen. Its power of etching
glass was known long before fluorine was suspected to
exist.
303. When a mixture of fluor-spar with peroxyd of man-
ganese and sulphuric acid is heated, a reaction takes place,
by which fluorine in an impure form is disengaged. If the
gas thus produced is passed through water having iodine sus-
pended in it, combination takes place, and a fluorid of iodine
is formed, which crystallizes in yellow scales. A fluorid of
bromine is formed by a similar process, which has been used
iTVthe photographic art with success. It is not crystallizable.
The precise composition of these bodies is not known
The atomic weight of fluorine is very nearly an aliquot
part of the equivalents of chlorine, bromine, and iodine, and
these four bodies form a well-marked natural family, closely
related by many similar properties.
CLASS III.
SULPHUR.
Equi valent, 16*0. Symbol, S. Density in vapor , .6*654.
304. History. — Sulphur is one of those elements which,
occurring abundantly in nature, have been known from the
remotest antiquity. It is found in many volcanic regions,
as in the Island of Sicily, the vicinity of Naples, in Cuba,
and many islands of the Pacific. Recent volcanic regions
producing sulphur are called solfataras. It is also found
in beds of gypsum, as a rock, near Cadiz in Spain, and at
Cracow in Poland. Sulphurets of iron, copper, and other
metals are widely diffused in the earth ; and in combination
as sulphuric acid, sulphur forms nearly half of the weight
of Common gypsum, or plaster of Paris.
305. Properties. — It is a straw-yellow, brittle solid at
common temperatures, having a gravity of 1*98. It is
tasteless, and without odor until rubbed. By warmth and
friction it acquires its well-known brimstone odor. It is a
non-conductor of heat and electricity. By friction it gives
How is fluorine disengaged ? What of its atomic weight ? 304. What
ii the history of sulphur ? 305. What are its equivalent and characters ?
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188
NON-METALLIO ELEMENTS.
negative electricity abundantly. It is very volatile, subliin-
ing in " flowers of sulphur" — minute crystals — even below
the melting point, or 226°. By this means it is freed from
earthy and other impurities. When fused below 280° it is
an amber-colored mobile fluid, lighter than solid sulphur,
which sinks in it. It is cast in moulds, giving roU sulphur.
On cooling, it shrinks so as to fall from the mould, (fig. 232.)
The roll sulphur held for a moment in the hand
gives a peculiar crackling sound, from the disturb-
ance of its particles by heat, and it often breaks
when so held. It is insoluble in water, and nearly
so in alcohol and ether. In oil of turpentine and
some other oils, it is partly soluble, and largely fio
in bisulphid of carbon. Vapor of alcohol also dis-
solves sulphur vapor.
Sulphur is very combustible, burning with a
blue flame and the familiar odor of a match, due
to the production of sulphurous acid. It combines
energetically with metals, forming sulphurets or
sulphids, supporting combustion like oxygen.
Fig. 232. Thus, a bundle of iron wires, as shown by Dr. Hare,
Fig. 233.
Fig. 235.
Fig. 234.
(fig. 233,) is rapidly burned with scintillations, when held
in the jet of sulphur vapor i» uing from a gun-barrel, the
end of which has been heated to redness, bits of roll sul-
phur thrown in, and the muzzle stopped with a cork.
306. Sulphur occurs in two distinct crystalline forms,
one of which is the right rhombic octohedrdn and the other
is the oblique rhombic prism. Figures 234 and 235 give its
usual form as found in nature or as crystallizing from solution.
When slowly cooled from fusion, as in a crucible, if the
crust formed on the surface be pierced while the interior is
How is it purified ? How does heat affect it ? What solubility has it f
How does it act on combustibles ? What is Hare's experiment ? 306.
What of ths form of sulphur ?
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SULPHUR. 189
still fluid, and the liquid part turned out,
the interior will present, as in fig. 236,
long, slender, compressed prisms. These
belong to the second form of sulphur.
This was one of the first instances of
dimorphism noticed by Mitscherlich.
307. The fusion of sulphur at different
temperatures presents remarkable facts. w „«-
At 226°-280° it is a clear, straw-yel- W™-
low fluid ; before reaching 280° it begins to grow darker ;
from that point to 300° it assumes a deep yellow color; at
374° it has an orange tint and becomes somewhat viscid ;
at 500° it becomes dull-brown, and at this high temperature
its viscidity is such that the vessel containing it may be
turned over without the sulphur falling out. Above this
last temperature it begins to grow more fluid. If at this
moment it is thrown into cold water, it remains pasty, trans-
parent, preserves its brown color, and may be drawn out
into long threads which have almost the elasticity of
caoutchouc. It regains its original brittleness only after
many hours. In this pasty state, sulphur may be moulded
by the hands, and is used to copy medallions and other
works of art. At 600° it is volatilized in a deep red-brown
vapor, resembling the vapor of bromine. The density of
its vapor is 6#654.
308. In its chemical relations, sulphur much resembles
oxygen. It forms sulphurets with most of the elements that
form oxyds, and these sulphurets often unite to form bodies
analogous to salts, as the oxyds do. Berzelius insists, very
properly, that its binary combinations, from their analogy
to the oxyds, should be called sulphidsy and not sulphurets.
Its uses are well known. It is one of the essential ingre-
dients of gunpowder, and is the basis of matches of all
kinds. Nearly all the sulphuric acid used in the arts is
made from it. The gas arising from its combustion is em-
ployed in bleaching straw and woollen goods ; and in medi-
cine it has a specific power in certain obstinate cutaneous
The flowers of sulphur of commerce nearly always have an
acid reaction, due to the sulphurous acid formed in subliraa-
Hcw is it obtained crystallized ? 307. Give the facts observed in its
fusion. What of its vapor? 308. What are tho relations of sulphur ?
What its uses?
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190
NON-METALLIC ELEMENTS.
tion. All the sulphur of commerce is obtained from iln
ores by sublimation in large chambers, — or, when cast in
blocks, by distillation and fusion in earthenware pots.
Compounds of Sulphur with Oxygen.
809. The compounds of sulphur and oxygen are nume-
rous, but only two of them will engage our attention at
present, namely:
Sulphurous acid SO«
Sulphuric acid SO,
The other compounds of sulphur and oxygen are ex-
pressed by the formula S909, S905, S,Os, S40s, SsOs.
310. Sulphurous Acid, S09. — Preparation. — This is the
sole product of the combustion of sulphur in oxygen, as in
the experiment figured in fig. 237, where burning sulphur
Fig. 237.
Fig. 238.
in a spoon is lowered into a jar of oxygen gas. Other
methods are used however in the laboratory to procure this
gas. One of the best is to heat in a retort or flask (fig.
238) an intimate mixture of six parts of peroxyd of manga-
nese and 1 of flowers of sulphur, in fine powder. The sul-
phur is burned at the expense of one portion of the oxygen
of the peroxyd of manganese. The sulphurous acid gas
is given off abundantly, and may be freed of a little vo-
latilized sulphur, by a wash-bottle. Mercury and copper
also decompose sulphuric acid, yielding sulphurous acid, by
aid of heat ; but the first method is much preferable on
every account. It must be collected in dry vessels or over
mercury.
309. What are its oxygen compounds?
prepared in fig. 237 ? How collected ?
310. What is SO.? How
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SULPHUR.
191
811. Properties. — Sulphurous acid is a colorless acid gas,
with a pungent^ suffocating odor, recognized as that of a
burning match. It extinguishes flame, A lighted candle
lowered into a jar containing it is extinguished, and the
edges of the flame, as it expires, are tinged with green.
A solution of blue litmus or purple cabbage turned into
a jar of the gas is at first reddened by the acid, and then
bleached. Articles bleached by it, after a time regain their
previous color. Water at 60° absorbs nearly fifty times its
volume of sulphurous acid, forming a strongly acid fluid.
Hence the necessity for collecting this gas over mercury, or
by displacement of air in dry vessels. Its avidity for mois-
ture is so great that it forms an acid fog with the water in
the atmosphere, and a bit of ice slipped under a jar of it
on the mercurial cistern is instantly melted; the water ab-
sorbs the gas, and the mercury rises to fill the jar.
312. Sulphurous acid is easily liquefied . under ordinary
pressures at 14° and below, using a tube with a bulb E, like
fig. 239, placed in a refrigerating vessel
F. The gas is first dried by chlorid of
calcium before passing into E. The
liquid gas is easily preserved by turn-
ing it into a tube drawn out like A B,
f fig. 240,) and previously refrigerated,
the part A serves for a funnel. The
' blowpipe flame seals it hermetically at
F* 239 a' an(* *fc ma^ k® ^en Preserve(^ f°r
lg' * future use. Under a pressure of two
atmospheres, this gas is condensed at a temperature Fig. 240.
of 59°. It is a colorless mobile fluid of a density of 1*42.
Its evaporation produces intense cold. If the ball of a
mercury thermometer is enveloped in cotton and moistened
by liquid sulphurous acid, the mercury is frozen, and a spirit
of wine jbhermometer indicates a temperature as low as
— 60°. By its evaporation water is frozen in a red-hot cru-
cible. It is a crystalline solid, transparent and colorless, at
105°, sinking in the liquid gas.
313. The volume of sulphurous acid is the same as that
of the oxygen employed in producing it. In other words, sul-
1
311. Give its properties. What of its bleaching? Of its avidity for
moisture? 312. llow and at what temperature liquefied? How collected
and preserved ? What of its sudden evaporation ? What temperaturo ?
313. What of the volume of SO*? Give the calculation.
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102 NON-METALLIC SLEMENTS.
phurous acid contains 1 volume of oxygen and £ volume
of sulphur yapor (258) condensed into 1 volume. Thus,
One volume of sulphurous acid density 2*247
6ub8tract the weight of 1 volume of oxygen 1*106
Leaving 1*141
Which represent! very nearly |th volume of sulphur
vapor=?*5! M09
6
By weight, sulphurous acid contains sulphur 50*87,
oxygen 49*13 = 100. One hundred cubic inches of it
weigh 68*70 grains.
3 14. Besides its use in bleaching straw and woollen goods,
sulphurous acid is employed as a bath for diseases of the
skin, and is a powerful disinfectant, even arresting putrefac-
tion and fermentation.
Sulphites are salts containing sulphurous aoid. Their
solutions are gradually changed to sulphates by absorbing
oxygen.
815. Sulphuric acid, SOs.HO. — This acid is one of the
most important compounds known ; its affinities are very
powerful, and no class of bodies is better understood by
chemists than the sulphates. In the arts great use is made
of sulphuric acid, many millions of pounds of it being an-
nually consumed in manufacturing nitric and muriatio
acids, the sulphates of copper and alum, in the process of
dyeing, and more than all, in the manufacture of carbonate
of soda from sea-salt.
It is not formed by the direct union of its elements, since
we have seen that only sulphurous acid can result from the
combustion of sulphur in oxygen. Sulphurous acid must
be oxydized to form sulphuric acid.
316. This may be done by passing a mixture of sulphur*
ous acid with common air over spongy platinum, heated to
redness in a tube, when there will issue from the open end
of the tube a mixture of sulphuric acid in vapor, with ni-
trogen from the air. In the arts, however, this process
cannot be used *, but sulphuric acid is made on a large scale
by bringing together sulphurous acid SOs, hyponitrio
acid N04, and water HO, all in a state of vapor, in a large
chamber, or series of chambers, lined with lead, when sul-
What of its density ? 314. What of the uses of sulphurous aoid ? 311b
What of SO. ? What it* use ? 316. How is SO, formed ?
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ftULPHUB.
IdS
Fig. 241.
phntous acid SOfl passes to a higher state of oxydation
SOs at the expense of one-half the oxygen of the hypo-
nitric acid N04, which thus becomes reduced to the state
of the deutoxyd ■ .%
ofmtrogen,(NOfl.) ]fl
The arrangement I ml P
employed is repre-
sented in fig. 241 .
A A is a chamber,
fifty feet or more
long, lined on all
aides with sheet-
lead. A very large
leaden tube B,
opening into one
end of the cham-
ber, communicates
with a furnace. Its lower end rests in a gutter 00 of
dilute acid, to prevent the effects of too much heat and the
escape of the vapors. The sulphur is introduced by a door
c to an iron pan; and a fire built beneath, n. The heat
melts the sulphur, which burns in a current of air passing
over it, and the sulphurous acid thus formed enters the
chamber, in company with air, and the vapors of nitric and
hyponitric acids set free from small iron pans standing over
the sulphur, and containing the materials to evolve nitric acid,
(sulphuric acid and saltpetre.) A small steam-boiler e
furnishes a jet of steam x as required, and a quantity of
water, covers the floor, which is inclined so as to be deepest
at h. A chimney with a valve or damper p allows the
3scape of spent and useless gases. Things being thus ar-
ranged, the chamber receives a constant supply of sulphur-
ous acid, common air, nitric acid vapor, and steam.
317. These compounds react with each other in such a
manner that the oxygen of the air is constantly transferred
to the sulphurous acid, to form sulphuric acid. Deutoxyd
of nitrogen NO, in contact with air becomes hyponitric acid
N04, and this last in presence of a large quantity of water is
transformed into nitric acid N05 and deutoxyd of nitrogen.
Thus, 6N04+»H0 =4N05+nHO+2NOr Now, sulphur-
ous acid, in presence of hydrated nitric acid (N05+wHO)
Explain the fig. 241. 317. Whence the oxygen to form SO* ? Give
the reactiona by the formula?.
♦ 13
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194
NON-METALLIC ELEMENTS.
is changed into sulphuric acid, and transforms the nitric acid
into hyponitric acid, thus renewing the reaction continually.
Thus, S0a+N05+»H0=S08+nH0+N04. In this way
a small quantity of nitric acid can he made to oxydize an
indefinite amount of sulphurous acid ; serving the purpose,
as it were, of a carrier of oxygen from the atmospheric air
to the sulphurous acid. Meanwhile the water on the floor
of the chamber grows rapidly acid ; and when it has attained
a specific gravity of about 1#5, it is drawn off and concen-
trated by boiling, first in open pans of lead until it becomes
strong enough to corrode the lead, and afterward in stills
of platinum until it has a density of about 1*8, in which state
it is sold in carboys, or large bottles, packed in boxes.
318. The process of forming sulphuric acid is easily
illustrated in the class-room by an arrangement of apparatus
like that shown in fig. 242. Two flasks b e are so connected
Fig. 242.
by bent tubes with a large balloon, that from one b sulphurous
acid, and from the other e deutoxyd of nitrogen are supplied
to the large balloon r. A third flask to furnishes steam as it
is wanted. Fresh air must be occasionally blown in at the
open tube t, the effete products escaping at o. Thus arranged,
the reactions above described take place. If but little vapor
of water is present, the sides of the globe are soon covered
What is the density of SO, in the chambers ? 318. Explain the figur*
and process 242.
Digitized
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SULPHUB 195
with a white crystalline solid, which appears to be a compound
of sulphurous and of nitrous acids (S0fl,N04.) This sub-
stance is decomposed by a larger quantity of water into sul-
phuric acid and hyponitric acid, and as it is known . to be
formed in the leaden chambers in large quantities, it is sup-
posed to have an important influence in the production of sul-
phuric acid.
319. This process by the leaden chambers is known in
the arts as the English process for sulphuric acid. Formerly
sulphuric acid was procured by distilling dry sulphate of
iron (green vitriol) in earthenware retorts, at a high tem-
perature. The oily fluid thus obtained was hence vulgarly
called oil of vitriol. This old process is still in use at Nord-
hausen, in the Hartz Mountains, producing an acid which is
commonly known as Nordhausen acid. It is the most con-
centrated form possible for fluid sulphuric acid. Sulphuric
acid unites with water in four proportions, forming definite
compounds, namely :
Nordhausen acid, sp. gr. 1*9 2(SO,)HO
Oil of vitriol, " 1-83 SO„HO
Acid of " 1-78 SO„HO+HO
Acid of " 1-63 SO*HO-f-2H
320. Nordhausen acid is a dark-brown, oily fluid, fum-
ing when exposed to air, and hissing like a hot iron when
water is let fall into it drop by drop. To mingle the two
rapidly in any quantity is unsafe. Cautiously heated in a
retort protected by a hood of earthenware A, as in fig. 243,
Fig. 243.
319. What is this process called ? What was the old one? Whence
the vulgar name ? What is the most concentrated SO, ? What hydrate*
tf SO, ? What of Nordhausen SO, ?
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196 NON-METALLIC ELEMENTS.
a white, crystalline, silky product distils oyer and is col*
lected in the cool receiver. This is anhydrous sulphurio
acid S08. It does not possess acid properties by itself, but
by contact with water or moisture it is changed to common
sulphuric acid. It must be preserved in tubes hermetically
seated. It has therefore been inferred that sulphuric acid
cannot exist without water, or that water is essential to the
acid property. In this case it is supposed that the oxygen
of the water joins that already with the sulphur, (forming
S04,) while the new compound thus produced unites with
hydrogen, forming S04H.
321. When exposed to a temperature of — 29°, sulphurio
acid freezes; and acid of 1*78 exposed to a temperature of
82° freezes in large crystals. One hundred parts of concen-
trated sulphuric acid contain 81 64 real acid, 18 36 water,
808HO. At 620° it boils, giving off a dense, white, and very
suffocating vapor. It is intensely acid to the taste, and
deadly, if by any accident it is swallowed, corroding and
burning the organs with intense heat. It blackens nearly
all inorganic matters, charring or burning them like fire. Its
strong disposition for water enables
us to employ it in desiccation, and
in the absorption of aqueous
vapor; using for this purpose a
shallow pan (fig. 243) containing
Fig. 244. S08HO, while the substance to be
dried is placed above it, and the whole then covered with a
low bell-jar or a tight-fitting plate.
322. Great heat is generated from the mixture of 4 parts
by weight of strong sulphuric acid and 1 of water, and a
diminution of bulk attends the mixing. The temperature
rises as high as 200°. So that water in a test tube
b (fig. 245) may be made to boil when placed in
the mixture contained in the beaker-glass a. If
common sulphuric acid is used for this purpose, it
becomes milky when water is added to it, from the
precipitation of sulphate of lead, derived from the
lg* ' boilers in which it was made. This salt is soluble in
strong sulphuric acid, but is precipitated by addition of
water.
How is crystalline SO, obtained? What formula is given? 321.
When does SO, freeze ? What of sp. gr. 178 ? Give other traits of SO*
522. What if water and SO, are mingled ? Why is the mixture milky ?
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SULPHUR.
197
323. Sulphuric acid forms sulphates, a class of salts most
minutely known to chemists, and many of which are fami-
liarly known in common life.
Chloride of barium, added to sulphuric acid, or to a soluble
•sulphate, throws down an abundant precipitate of sulphate
of baryta, a salt insoluble in all menstrua. The same test
gives a precipitate also with sulphurous acid, (sulphite of
baryta,) but the latter is soluble in chlorohydric acid.
324. There are several chlorids of sulphur. The apparatus
figured in fig. 245 shows the manner of preparing one of
Fig. 246.
them C1S9. Sulphur is placed in the small retort P and
fused by the lamp beneath, while a current of chlorine libe-
rated from the ballon c, and dried over the chloride of cal-
cium tube a, is delivered gently by the descending tube almost
in contact with the fused sulphur in P. Combination en-
sues, chloride of sulphur distils over and is condensed in the
receiver r, kept cool by water from the fountain. This
chlorid of sulphur is a reddish-yellow fluid, of a disagreeable
odor. It boils at 280°, giving a vapor of density 4*668.
The density of the liquid is 1*68. Water decomposes it,
forming sulphur and chlorohydric acid. One volume of this
substance in vapor is formed of
1 toL chlorine 2*440
i " sulphur °-f* 2-218
Giving the theoretical density 4*658
While experiment gives 4*668
323. What salts does SO. form? What tests for SO.? 324. ETow it
CIS, formed? Describe fig. 245. What are its characters? Give its
volume and density.
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198 NON-METALLIC ELEMENTS
The bromids and iodids of sulphur possess very little
interest.
SELENIUM.
Equivalent, 40. Symbol, Se. Density, 4-3.
325. History and Properties. — This element was dis-
covered by Berzelius, in 1818, and named by him from
selene, the moon. It is associated in nature with sulphur
in some kinds of iron pyrites, and in a lead ore from
Saxony, and also at the Lipari Islands combined with sul-
phur and accompanied by other volcanic products.
It closely resembles sulphur in most of its properties, as
well as in its natural associations. At common tempera-
tures it is a brittle solid, opake, and having a metallic lustre
like lead, but in powder it is of a deep red color. Its
specific gravity is 4-28 for the vitreous, and 4-80 for the
granular variety from slow cooling. It softens at 212°,
and may then be drawn out into red-colored threads ; at a
little higher temperature it melts completely, and boils at
650°, giving a deep yellow vapor without odor. It passes
through the same changes of state by heat as sulphur. It
is insoluble. When heated in the air, it combines with
oxygen, and gives out a disagreeable and strong odor, like
putrid horse-radish. Before the blowpipe, on charcoal, it
burns with a pale blue flame, and ^ of a grain, so heated,
will fill a large apartment with its odor. It is a non-con-
ductor of heat and of electricity, and excites resinous elec-
tricity.
326. The compounds of selenium with oxygen are three,
two of which are acids, analogous to sulphurous and sul-
phuric acids. They are —
Oxyd of selenium SeO
Selenious acid SeO*
Selenic acid SeOt
Oxyd of selenium is formed when selenium is heated in
the air. It is a colorless gas, and possesses the strong odoi
before mentioned.
327. Selenious acid is formed when selenium is burned
325. What of selenium? Give its characters. Its equivalent 326
What compounds of 0 has it ?
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SELENIUM. — TELLURIUM — NITROGEN. 199
in a current of oxygen gas, as in the tube a, (fig. 247.) A
small portion of selenium is placed at b,
and fused by a lamp ; at this temperature,
oxygen flowing, from a reservoir, in sit a,
combines with the selenium, forming SeOB,
which is a white crystalline body, very so-
luble in water, and sublimed by heat un-
changed. Selenic acid is formed when sele-
nium is burned by nitrate of potash, formiDg ^
selenate of potash. It resembles sulphuric %
acid in its properties. Both selenious and Fi ^^T
selenic acids form salts with the alkalies
and bases, every way similar to the sulphites and sulphates,
Selenid of sulphur is found native among volcanic products.
TELLURIUM.
Equivalent, 64. Symbol, Te.
328. This rare substance is related to selenium and sul-
phur. It forms compounds with gold and bismuth, found
native as minerals. Pure tellurium is a tin-white, brittle
substance, with a metallic lustre, and density of 6*26. It
melts at low redness, and takes fire in the air, forming tel-
lurous acid, TeOa. With hydrogen it forms a compound,
analogous to arseniuretted hydrogen, and sulphuretted
Hydrogen.
CLASS IV.
NITROGEN, OR AZOTE.
Equivalent, 14. Symbol, N. Density, *972.
329. Preparation and History. — This gas forms four-
fifths of the air, and is an essential constituent of most
organic substances. It was first described by Rutherford, in
1772. It is only mingled mechanically with oxygen in our
atmosphere, which is not a chemical compound.
It is most easily procured for purposes of experiment
from the atmosphere, by withdrawing the oxygen of the air
327. What of selenious acid ? 328. What of tellurium ? 329. Give the
history of nitrogen.
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200
NON-METALLIC ELEMENTS.
by phosphorus. This is easily
done by burning some phos-
phorus in a floating capsule,
under an air-jar, upon the pneu-
matic cistern, (fig. 248.) The
strong affinity of phosphorus foi
oxygen enables it to withdraw
every trace of this element,
leaving behind nitrogen nearly
pure, containing about 7^th of
phosphorus. The water soon ab-
Fig. 248. g^jjg tne snow-white phosphoric
acid. The first combustion of the phosphorus expels a
portion of the air by expansion ; but as the combustion pro-
ceeds, the water rises in the jar, until it occupies about
•Jth of its space. When this experiment is performed over
mercury, the white phosphoric acid remains unchanged.
Nitrogen may be procured pure by passing a current of air
over copper turnings in a tube of hard glass heated to
redness : the oxygen is all retained by the copper, while
nitrogen is given off. Nitrogen can also be obtained, by
decomposing strong water of ammonia, by chlorine gas :
the ammonia yields its hydrogen to the chlorine, and the
nitrogen is given off. The apparatus (fig. 249) may be
used for this
0 purpose, in
which p is
an evolution-
flask for chlo-
rine, and the
strong am-
monia water
is in to. Great
care should
be taken to
prevent all
the ammonia
becoming sa-
turated, as in
Fig. 249. that case a
How prepared ? How from ammonia ? What precaution is note i ?
U'bat is the reaction ?
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IOTB0GEN. 201
rerj dangerous compound (chloride of nitrogen) will be
formed by the action of the chlorine, on the chlorid of am-
monia produced in the process. The nitrogen collects in n.
3C1+NH3=8HCL+N.
830. The properties of nitrogen are mostly negative. It
is a colorless/ tasteless, odorless, permanent gas. It has not
been liquefied. It combines directly with no element, but
indirectly it enters into most powerful combinations. In the
atmosphere it appears to act chiefly as a diluent of oxygen.
Its density is 0*972, or a little less than air. A
taper immersed in it (fig. 250) is extinguished im-
mediately. An animal placed in nitrogen dies from
want of oxygen, and not because of any poisonous
character in the gas, as might be inferred from its
abundance in our atmosphere. Hence its name
azote, from a privative, and the Greek zoe, life, to
deprive of life. Nitrogen is derived from Latin
nitrium, nitre, and gennao, I form. One hundred s'
volumes of water dissolve about two and a half volumes of
nitrogen.
The Atmosphere.
331. The mechanical properties of the atmosphere have
already been considered, (20.) The number and propor-
tion of the constituents of the atmosphere are constant,
although their union is only mechanical. Repeated analyses
have shown that atmospheric air is always formed of nitro-
gen, oxygen, watery vapor, a little carbonic acid, traces
of carburetted hydrogen, and a small quantity of ammo-
nia. The air on Mount Blanc, or that taken in a bal-
loon by Gay-Lussac from 21,735 feet above the earth,
had the same chemical composition as that on the surface,
or at the bottom of the deepest mines. The carbonic acid,
being liable to changes in quantity from local causes, is
found to vary slightly.
To the constituents already named, we may add the aroma
of flowers and other volatile odors, and those unknown,
mysterious agencies, which affect health, and are called mias-
mata. From the results of numerous analyses, we state the
composition of the atmosphere in 100 parts, to be —
330. What its properties? What its function in air? How affects
life? Hence, what name has it? Define the word nitrogen. 33L.
What of air ? How are its constitnents ? What of its purity ? What
arc its constituents ?
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202
NON-METALLIC ELEMENTS.
Byiretght By
Nitrogen 76-90 79-10
Oxygen 23-10 20-90
100-00
100-00
To this we must add from 3 to 5 measures of carbonic
acid in 10,000 of air, about the same quantity of carburetted
hydrogen, a variable quantity of aqueous vapor, and a trace
of ammonia. Nitric acid is also sometimes found in small
quantity in rain-water, formed in the air by the electrical
discharges of thunder-clouds, and washed out by the rains.
100 cubic inches of dry air weigh 31*011 grains. In 10,000
volumes the constitution of the air will be, therefore —
Nitrogen 7901
Oxygen 2091
Carbonic acid 4
Carburetted hydrogen 4
Ammonia trace
10,000
332. The analysis of air is accomplished by any sub-
stance which will remove the oxygen. But the accurate
performance of this process requires numerous minute pre-
cautions, any notice of which is out of place here. Eu~
diometry is the term applied to the common method of
analysis for air. This term is derived from Greek words
signifying a good condition of the air, and was employed
because it was formerly thought that an analysis of the air
would show if it was in a salutary
condition. One of the simplest
means of analyzing the atmosphere,
consists in removing the oxygen
by the slow combustion of phos-
phorus. For this purpose a stick of
phosphorus is sustained on a plati-
num wire (fig. 251) in a confined por-
tion of air, contained in a graduated
glass tube, whose open end is be-
neath water. A gradual absorption
takes place, and in about twenty-
four hours the water ceases to rise
in the tube, by which we know that
Fig. 251. the phosphorus has removed all Fi*' 25L
Give analyses of air ? What is its composition in 10,000 volume* T
*32. How analyzed ? What is eudiometry ?
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NITROGEN. 203
the oxygen. The water absorbs the resulting phosphorous
acid, and we may read off, by the graduation on the tube,
the amount of oxygen removed. A narrow-necked bolt-head
shows this result in a more striking manner in the class-room,
the large volume of air in the ball causing a very apprecia-
ble rise of water in the stem during the course of a lecture,
(fig. 252.) When speaking of hydrogen, we will mention
another method of eudiometry. The agency of the air in
combustion and respiration will also be explained under
the appropriate heads. The air dissolved in water, and
on which water-breathing animals live, is found to be
decidedly more rich in oxygen than the atmospheric air.
This is owing to the fact that oxygen is much more abun-
dantly absorbed by water than nitrogen, in the proportion
of -046 to *025. These numbers express, respectively, the
ratio of solubility of the two gases in water. The air in
water has the constitution —
By analysis. By theory.
Oxygen 32 31'5
Nitrogen 68 68*5
100 100-0
Compounds of Oxygen and Nitrogen,
333. Nitrogen unites with oxygen, forming five com-
pounds, three of which are acids. Their names and consti-
tution are thus expressed : —
Symbol.
Protoxyd of nitrogen (nitrous oxyd) ; NO
Deutoxyd of nitrogen (nitric oxyd) NO*
Nitrous acid. NOt
Hyponitric acid N04
Nitric acid NOt
As nitric acid is the source whence all the other com-
pounds of nitrogen are obtained, we will commence with
the history of that compound : —
This important compound was known in the earliest days
of alchemy, but it was Cavendish who, in 1785, first made
known its constitution. He formed it by direct union of its
elements over a solution of potash, by aid of a series of
electrical sparks continually passed through a mixture
of the two gases N and O, for several successive days,
What of air dissolved in water ? 333. What are the oxygen com.
pounds of nitrogen? Give the series. What is the source of other ni-
trogen compounds ?
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204
NON-METALLIC ELEMENTS.
in a close tube, (fie 258 )
The ends of the tube, con-
taining the gases and pot
ash solution, dipped into
and contained mercury as
a conducting medium for
the electricity. Nitre was,
Fig. 253. subsequently, found in the
solution, thus giving the strongest evidence of a union of
the two gases.
334. Nitric Acid, "Aqua Fortis," N05H0.— This power-
ful acid is obtained by heating saltpetre (nitrate of potassa)
or nitrate of soda with strong sulphuric acid. The nitric
acid is displaced by the sulphuric, and distils over, being
much more volatile than the sulphuric acid.
335. The arrangement
of apparatus required is
seen in figure 254. The
retort R contains the
nitre in small crystals,
and should be supported
in a sand-bath ; or, if the
quantity of nitre does not
exceed a pound or two, a
naked fire answers very
well. An equal weight
of 8ulphurie acid is then
added, with care not to
soil the interior neck of
Ij: \f^ *ne retork Heat is gradu*
^ — -Jr ally applied, and the re-
Fig. 254. ceiver kept cold by a con-
stant stream of water distributed over its surface by a
piece of filtering paper. No corks or luting of any kind
can be used about the apparatus, as the vapors of concen-
trated nitric acid attack all organic substances with energy,
as also the alumina and other bases of clay-lute. In the
first moments of the operation the vessels are filled with
deep-red vapors of hyponitrous acid, due to the decomposi-
tion of the first formed portions of nitric acid by the great
334. What is the history of NO,? What was the experiment of Ca-
? endish ? What is the process, fig. 254 ? What precautions are given f
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NITROGEN. 20$
excess of sulphuric acid. As the distillation proceeds,
the vessels become colorless and the distillate very nearly
so. The red vapors appear again at the close of the opera-
tion, and furnish a signal when to arrest the process and
change the recipient. This is because the temperature rises
toward the close, to the decomposing point of nitric acid.
The bisulphate of potash in the retort remains some time
after the heat is withdrawn in a state of quiet fusion, having
a temperature of about 600°. When reduced to about 250°,
hot water may be added in small portions at a time, and
with care the retort may be saved, although it is often
sacrificed from the crystallization of the sulphate of potassa.
In the arts this process is conducted in large vessels of iron
set in brick furnaces.
336. Properties. — Nitric acid is a mobile fluid, nearly
colorless, fuming, intensely acid, staining the skin instantly
yellow, and acting with great energy on most metals and
organic substances. It has usually a reddish color, due to
the presence of hyponitric acid. When most concentrated
it has a density of 1*51-1*52, and contains 86 parts in
100, real acid. It boils at 187°. It is decomposed by
light, evolving red fumes of hyponitric acid and free oxygen,
which sometimes forcibly expels the stopper. It should,
therefore, be kept in a dark place, or in black bottles.
Poured on pulverized charcoal which has recently been
ignited, it deflagrates it with energy ; warm oil of turpentine
is immediately fired by it; and its action on phosphorus is
too violent to be a safe experiment, without great precau-
tion. The concentrated acid freezes at — 40° • but if
diluted with half its weight of water, it freezes at about 1 J°.
The green hydrous acid (343) freezes to a bluish-white solid.
The dilute acid yields by distillation a product, at first more
concentrated, but when it has a boiling point of 250°
the product is of uniform strength, and contains 40 parts
real acid in 100. Like sulphuric acid, it forms several
definite hydrates, of which the highest is the strong acid
described above. Anhydrous nitric acid N05 has been lately
obtained by decomposing dry nitrate of silver by perfectly
dry chlorine. Anhydrous ntrio acid crystallizes in colorless
rhombs, which fuse at 30°; and it boils at 50° with decom-
336. What are the properties of NO,? How doeiit aet on oombustt-
blea? What of its hydrates? Of anhydrous NO,?
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206 NON-METALLIC ELEMENTS.
•
position. It is soluble in water, evolving much heat, and
yielding colorless, hydrous nitric acid
337. Nitric acid is a powerful solvent of the metals, and
carries them to their highest state of oxydation. This
action is always attended with the production of binoxyd of
nitrogen NOa and hyponitric acid. The nitrates are aU
soluble in water. When fused with carbon they are de-
composed with brilliant deflagration of the charcoal. Nitrfo
acid decoloriies a solution of sulphate of indigo, and with a
few drops of chlorohydric acid it dissolves gold-leaf.
Passed in vapor through a poroelain tube heated white-
hot it is decomposed, yielding nitrogen and oxygen.
338. Protoxyd of Nitrogen NO, Nitron* Oxyd, or Laugh-
ing Gas. — This gaseous compound of nitrogen is prepared
by heating nitrate of ammonia NH40.N05 in a glass flask,
(fig. 255,) by the aid of a spiritjamp.
The gas is given off at about 400° to
500°, and is delivered by the bent tube
to an air-jar on the pneumatic trough.
The uitrate of ammonia, which is a
crystalline white salt formed by neu-
tralizing dilute nitric acid by carbonate
of ammonia, is so constituted as to be
resolved by heat alone into nitrous
oxyd and water; thus, NH40.N05
become by heat 4HO + 2NO Con-
sequently, the equivalents of these ele-
ments show us, that 80 grains of nitrate
I of ammonia, will yield 44 grains of
Fig. 255. nitrous oxyd, and 36 grains of water.
Care must be taken not to heat this salt too highly, as it then
yields nitric oxyd and hyponitric acid. If a red cloud is seen
during any part of the operation, the heat must be abated.
339. Properties. — Protoxyd of nitrogen is a colorless gas,
with a faint, agreeable odor, and a sweetish taste. With a
pressure of fifty atmospheres at 45° F. it becomes a clear
liquid, and at about 150° degrees below zero freezes into a
beautiful clear crystalline solid. By the evaporation of this
solid, a degree of cold may be produced far below that of
the carbonic acid bath (151) in vacuo, (or lower than — 174°
337. How does it affect metals ? What of nitrates ? 338. How is NO
prepared ? Give the reaction ? What precaution is noted ? 339. What
dire its properties ? What of its liquid ? What temperature ?
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NITROGEN. 307
F.) It evaporates slowly, and does not freeze, like carbonic
acid, by its own evaporation. The specific gravity of
nitrous oxyd is 1*527; 100 cubic inches of it weigh 47-29
grains. Cold water absorbs about its own volume of this
gas. It cannot, therefore, be long kept over water, but may
be collected over the water-trough in vessels filled with warm
water. It supports the combustion of a candle,
(fig. 256,) and sometimes relights its red wick with
almost the same promptness as pure oxygen.
Phosphorus burns in it with great splendor.
With an equal bulk of hydrogen, it forms a mix-
ture that explodes with violence by the electric
spark or a match : the residue is pure nitrogen,
the oxygen forming water with the hydrogen.
Passed through a red-hot porcelain tube it is re- Flg* 256'
solved into its constituent gases. One volume of protoxyd
of nitrogen contains
1 volume of nitrogen 0*972
£ volume of oxygen 0*552
Theoretical density 1*524
340. It may be breathed without injury, but it produces
a remarkable excitement in the system, amounting to in-
toxication, and, if carried far, even to insensibility. To pro-
duce these effects without injury, it should be quite pure,
and especially free from chlorine, and inhaled through a
wide tube, from a gas-holder or bag. The presence of chlorid
of ammonium in the nitrate employed should be especially
avoided, as producing chlorine. There is a sweetish taste, and
a sensation of giddiness, followed by joyous or boisterous
exhilaration. This is shown by a disposition to laughter, a
flow of vivid ideas and poetic imagery, and often by a strong
disposition to muscular exertion. These sensations are
usually quite transient, and pass away without any resulting
languor or depression. In a few cases, dangerous conse-
quences have followed its use, and it should always be em-
ployed with great caution. In at least one case, in the labo-
ratory of Yale College, it produced a joyous exhilaration of
spirits, which continued for months, and permanent restora-
tion of health. Its effects, however, on different individuals,
are various.
How does it act on combustibles? What is its volume ? 340. What
its effect if breathed?
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208
NON-METALLIO ELEMENTS.
Fig. 257.
841 Deutoxyd or Binoxyd of Nitrogen, Nitric OxytL—
This gas is easily prepared by adding strong nitric acid to
clippings of sheet-copper, contained in
a Dottle arranged with two tubes, (fig.
257.) A little water is first put with the
copper cuttings, and the nitric acid
poured in at the tall funnel-tube until
brisk effervescence comes on. In this
case the copper is oxydized by a part of
the oxygen of the acid, and the oxyd thus
formed is dissolved by another portion of
acid. The nitrogen, in union with the
two equivalents of oxygen, is given off
as nitric oxyd, which, not being ab-
sorbed by water, may be collected over
the pneumatic-trough. Many other
metals have the same action with nitric acid. The action
is renewed by continued additions of nitric acid. It is
also obtained very pure by heating nitrate of potash
K0.N05 with a solution of protochlorid of iron FeCl, in
an excess of chlorohydric acid.
342. Properties. — Nitric oxyd is a transparent, colorless
gas, tasteless and inodorous, but excites a violent spasm in
the throat when an attempt is made to breathe it. It has
never been condensed into a liquid. Its specific gravity is
1*039, and 100 cubic inches weigh 32*22 grains. It con-
tains equal measures of oxygen and nitrogen uncondensed.
A lighted taper is usually extinguished when immersed
in it, but phosphorus previously well inflamed will burn in
it with great splendor. When this gas comes into contact
with the air, deep-red fumes are produced, by its union with
the oxygen of the air to form hyponitric acid. If to a tall
jar, nearly filled with nitric oxyd, standing over the well
of the cistern, pure oxygen gas be turned up, deep blood-
red fumes instantly fill the vessel, much heat is generated,
and a rapid absorption results from the solution of the red
nitrous acid vapors in the water of the cistern.
343. Nitric oxyd is rapidly absorbed by solution of green
sulphate of iron, forming a deep-brown solution of sulphate
of peroxyd of iron. Colorless nitric acid also absorbs nitric
341. What of NO,? How evolved? 342. Give its properties. Why
irrespirable ? How affects combustibles ? In contact with air produces
what? Give an illustration. 343. What absorbs it ?
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NITROGEN.
209
oxyd, and acquires first a yellow, then an orange-red, and
finally a lively green color. This operation is best con-
ducted in an apparatus of bottles arranged as in fig. 258,
and called Woulf *s apparatus. The gas generated in a passes
Fig. 258.
in succession into the fluid of each vessel. The central tubes
serve as safety-tubes. The colors named above are beauti-
fully seen in the several bottles, the first becoming green
before the last has gained an orange tint. By carefully
heating the green acid, the hyponitric acid contained in it
may be expelled. The deutoxyd of nitrogen decomposes
the nitric acid, forming hyponitric acid, (345.)
344. Nitrous Acid, N08. — This is a thin, mobile liquid,
formed from the mixture of four measures of deutoxyd of
nitrogen with one measure of oxygen, both perfectly dry,
and exposed after mixture to a temperature below zero of
Fahrenheit. It has an orange-red vapor : the liquid at
common temperatures is green, but at zero is colorless.
Water decomposes it, forming nitric acid and deutoxyd of
nitrogen. It forms salts, called nitrites.
345. Hyponitric Acid, N04. — When the green nitric
acid obtained in the process just described (fig. 258) is
cautiously distilled, hyponitric acid in notable quantity is
collected in the refrigerated receiver. The apparatus is ar-
ranged as in fig. 259. The green acid is heated in the retort
r, by means of a water-bath w, over the lamp c, and the pro-
duct is collected in the U tube t, placed in a refrigerant mix-
ture. This acid is also procured by decomposing nitrate of
lead in a porcelain retort by heat. Oxygen and hyponitric
How does it affect NO, ? Explain the apparatus, fig. 257. 344. What
of NO ? What are its salts ? 345. Hem is NO« obtained?
14
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210
NON-METALLIC ELEMENTS.
acid are obtained, and the latter is collected as above. Tha
is an orange-colored fluid, density 1-42, becoming red when
Fig. 259.
heated. It boils at 82°, and solidifies at 8°. Its vapor is
intensely red, and has the density 1*73. This compound is
hardly entitled to be considered as an acid, it does not form
salts, but in contact with a base is decomposed, producing
a nitrate and a nitrite.
PHOSPHORUS.
Equivalent, 32. Symbol, P. Density, 1-863.
846. Bistory. — Phosphorus is an element nowhere seen
free in nature, but it exists largely in the animal kingdom,
combined with lime, forming bones, and is found also in
other parts of the body. In the mineral kingdom it exists
widely diffused in several well-known forms, particularly in
the mineral called apatite, which is a phosphate of lime.
It is introduced into the animal system by the plants used
as food, whose ashes contain a notable quantity of phos-
phate of lime. It was discovered in 1669, by Brandt, an
alchemist of Hamburg, while engaged in seeking for the
philosopher's stone, in human urine. Its name implies its
most remarkable property, (phos, light, and phero, I carry.)
S47. Preparation. — Phosphorus is procured in immense
How as in fig. 258 ? What are its properties ? 346. Give the historj
of phosphorus. Whence its name?
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PHOSPHORUS.
211
if&antiiaes from burnt bones, for the manufacture of friction
matches. The bones are calcined until they are quite
white ; they are then ground to a fine powder, and fifteen
parts of this are treated with thirty parts of water and ten
of sulphuric acid : this mixture is allowed to stand a day or
two, and is then filtered, to free it from the insoluble sul-
phate of lime, formed by the action of the oil of vitriol on
the bones. The clear liquid (which is a soluble salt of lime
and phosphoric acid) is then evaporated to a syrup, and a
quantity of powdered charcoal added. The whole is then
completely dried in an iron vessel and gently ignited. After
this, it is introduced into a stoneware or iron retort, to
which a wide tube of copper is fitted, communicating with a
bottle in which is a little water, that just covers the open
end of the tube, (fig. 260 :) a small
tube carries the gases given out to a
chimney or vent. The retort being
very gradually heated, the charcoal
decomposes the phosphoric acid, car-
bonic acid and carbonic oxyd gases are
evolved, and free phosphorus flows
down the tube into the bottle, where it
is condensed. The operation is a criti-
cal one. Splendid flashes of light are
constantly given out during the ope-
ration, from the escape of phosphu-
retted hydrogen. The crude phos-
phorus thus obtained is purified by
melting under water, and it is then cast into glass tubes,
forming the sticks in which it is sold.
348. Properties. — Phosphorus is an almost colorless, semi-
transparent solid, which at ordinary temperatures, cuts with
the consistency and lustre of wax. At 32° it is brittle,
and breaks with a crystalline fracture. Exposed to light, it
soon becomes yellow and finally red. Its density by the
late determinations, is 1 -826-1*840, and liquid 1-88. It is
insoluble in water; but dissolves readily in bisulphuret of
carbon ; in ether, alcohol, and various oils, it is partially
soluble. It is obtained in fine dodecahedral crystals, from
its solution in bisulphuret of carbon. It melts at 111° to
Fig. 260.
347. How prepared? How is the crude PO, decomposed? 348*
What are its characters ? How crystallized ? How soluble ?
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812 N0N-M1TALLI0 ELEMENTS.
ft limpid liquid : when fused beneath water, it is safely re-
cast in small sticks, by drawing it into narrow glass tubes.
It boils at 554°, forming a colorless vapor with the density
4-226. Owing to its great inflammability, it is a very un*
safe substance to handle, producing severe burns, very dif-
ficult to heal. Any impurity, such as the presence of partly
oxydized phosphorus, as from the nitrogen experiment,
(fig. 248) renders it much more liable to inflammation. The
heat of the hand, or the least friction, suffices to set fire to
it. It must be kept under water, to which alcohol enough
may be added to prevent its freezing in winter. If exposed
to the air, it wastes slowly away, forming phosphorous acid.
When in the dark, it is seen to be luminous. The vapor
which comes from it has a strong garlic odor, which does
not belong, either to the pure phosphorus, or its acid com-
pounds. By this action the ozone of Schonbein is formed,
(279.) A little defiant gas, the vapor of ether, or any
essential oil, will entirely arrest the slow oxydation of phos-
phorus in air. The presence of nitrogen or hydrogen seems
to be essential to this operation, as, in pure oxygen, phos-
phorus does not form phosphorous acid at common temper-
atures. It burns in pure oxygen gas with great splendor,
forming one of the most brilliant experiments in chemistry,
(354.) Phosphorus is a violent poison.
349. Red, or amorphous phosphorus, is a peculiar iso-
meric modification of common phosphorus, produced by heat-
ing it for a long time near its point of vaporization, in an
atmosphere of hydrogen, or of carbonic acid. This effect
takes place also when phosphorus is long exposed to the
light : the exterior of the sticks becomes encrusted with a
red powder, formerly supposed to be oxyd of phosphorus.
Red phosphorus presents properties strikingly different from
common phosphorus : the latter fuses, as we have seen, at 111° ;
the former remains solid even at 482°, and at 500° returns
to the condition of ordinary phosphorus. Red phosphorus
can be preserved without change in air, has no sensible
odor, and may even be heated to 392° without becoming
luminous. Its specific gravity is 1-964. It does not com-
bine with sulphur at the fusion point of that body, while
What renders it more inflammable ? How is it kept ? If exposed to
air, what happens ? How is its combustion in 0 managed in fig. 264 1
349. What is red phosphorus ? How produeed J Give its character*
How is it recognized as the same bod/ ?
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PHOSPHORUS. 21S
common phosphorus unites with sulphur with a terrible ex-
plosion. It is only from the identity of the compounds
from these two modifications of phosphorus that it is shown
that they are indeed one and the same body. The red
phosphorus is preferred, from its greater safety, in the manu-
facture of matches, and in medicine.
Compounds of Phosphorus with Oxygen.
350. The compounds of phosphorus with oxygm are
four in number, namely :
Oxyd of phosphorus P«0
Hypophosphorous acid.... PO
Phosphorous acid PO.
Phosphoric acid POi
351. Oxyd of phosphorus is formed when a stream of
oxygen gas is allowed to flow from a tube __._
upon phosphorus, melted under warm water,
as seen in fig. 261. The phosphorus burns
under water and forms a brick-red powder,
which is the oxyd in question, mingled with
much unburnt phosphorus. The presence of
oxyd of phosphorus with unburnt phosphorus
renders the latter much more inflammable.
The water over the oxyd of phosphorus in
this experiment becomes a solution of phos-
phorous and phosphoric acids. ^ 261#
352* Hypophosphorous acid is a powerful deoxydizing
agent, decomposiBg the oxyds of mercury and copper, and
even sulphuric acid, with precipitation of sulphur and libe-
ration of sulphurous acid : by these reactions it becomes
exalted to phosphorus or phosphoric acid. It is prepared
by decomposing the hypophosphite of baryta.
353. Phosphorous acid P08 is formed by the slow com-
bustion of phosphorus in the air : a stick of phosphorus ex-
posed to air is immediately surrounded by a white cloud of
this acid. Sticks of phosphorus, cast in small glass tubes,
may be arranged as m fig. 262, in a funnel. Each stick is
placed in a glass tube ahf slightly larger than itself, and drawn
to a pointy 5g. 2ti3 ■ and these are arranged in a funnel and
350. What are the 0 compounds of P? 351. How is P«0 formed?
S52. What of PO ? 353. How is PO. formed ?
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2U
NON-METALLIC ELEMENTS.
covered with an open bell,
to keep out dust and- the
fluctuations of air. The
action then proceeds gra-
dually, and a considerable
quantity of the product
is collected in the bottle
beneath. When formed by
combustion of phosphorus
in a limited quantity of \Jj
air, phosphorous acid is a _. OM
Fig. 262. dry white powder. Con-**263*
tact of humid air converts it into the above form, which
always contains some phosphoric acid. It is one of the less
powerful acids. By heat it decomposes the oxyds of mer-
cury and silver. It forms salts called phosphites.
354. Phosphoric Acid, P05. — This acid is formed by the
action of strong nitric acid on phosphorus, as well as from
bones, by the action of sulphurip acid, as in the process for
obtaining phosphorus, (347.) ^jjhen phosphorus is burned
in a full supply of oxygen^gal^ this acid is the product.
For this purpose, an arrangement like fig. 264 is adopted.
Fig. 264.
The large globe is filled by displacement with oxygen,
dried by the chlorid of calcium vessel c. The phosphorus
is burned in a capsule, supported at the bottom of the globe
on a bed of dry gypsum, and is dropped in at pleasure by
the porcelain tube t, whose orifice is closed by a cork. The
Describe the arrangement, fig. 262. What are its properties 1 S64.
How is POa formed ?
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PHOSPHORUS. 216
bottle with two necks receives the vapors of phosphoric acid,
a draft being kept up by the porcelain tube p, which is
made to act as a chimney, by the alcohol flame from the
cup a. In this way the combustion is kept up at pleasure,
as fresh oxygen is supplied by the hose p. In a dark room
this experiment forms a most magnificent display of mellow
light. Such is its avidity for water, that phosphoric acid
hisses like a hot iron when added to it. It makes an intensely
acid solution, which, evaporated to dryness and ignited, yields
on cooling a transparent glassy solid, called glacial phos-
phoric acid.
355. Phosphoric acid forms three distinct hydrates with
water, and three classes of salts. These salts give a beauti-
ful example of the substitution of a metal for hydrogen in
the production of salts. Let M represent a metal in the
following formulae, and we have
Actda, Salt*,
Monobasic or metaphospboric acid HO.POf, giving metaphosphate MO.PO,
Bibasic or pyrophosphorie acid ~~ 2HO.PO*, " pyrophosphate 2MO.PO>
Tribaaic or common phosphoric acid.. SIlO.POi, " phosphate 3MO.PO*
For a full account of these interesting modifications of
phosphoric acid, the student is referred to Dr. Graham's
excellent Elements of Chemistry.
The compounds of phosphorus, especially the phosphates
of lime and of magnesia, are very widely distributed in nature,
and enjoy an important function in the economy of life.
The tribasic phosphates produce with nitrate of silver a yel-
low precipitate ; with solutions of magnesia and ammonia a
fine granular one, (ammonio-phosphate of magnesia;) and
the molybdate of ammonia detects the smallest trace of this
acid even in the fluids of the body.
356. Ghlorids of Phosphorus. — Of these there are two,
the perchlorid PC1S, and the terchlorid PC18. The first
is formed when phosphorus is introduced into a jar of dry
chlorine. It inflames and lines the sides of the vessel
with a white matter, which is the perchlorid of phosphorus.
This compound is very unstable, and when put in water both
it and the water suffer decomposition, and hydrochloric and
phosphoric acids result. To form the other, PC18, the appa-
ratus used for the chlorid of sulphur may be employed, sub-
stituting phosphorus for sulphur in the retort P, (fig. 245.)
How from bones ? What are its properties ? What is glacial PO, t
865. What of its hydrates ? What tests for PO, ? 356. What chloridt
oC phosphorus are there ? How is PCI, formed ?
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216
NON-METALLIO SLXMENTS.
The bromids, iodids, and sulphurets of phosphorus have
the same constitution as the chlorids, and are formed by
contact of the elements. They are unimportant, and the
sulphuret is a very violent and dangerous compound to form*
CLASS V. THE CARBON GROUP.
CARBON.
Equivalent 6. Symbol, C. Specific gravity in vapor, 0*829.
857. History. — Carbon is an element found in all three
kingdoms of nature. Charcoal and mineral coal, which are
the two common forms of carbon, have been known from
the remotest times of history. Its great importance in the
daily wants of society makes it one of the most interesting
of the elementary bodies, and our interest in it is not dimin-
ished from the fact that the charcoal and mineral coal which
we use as fuel and the black-lead of our pencils are, essen-
tially, the same thing with that rare and costly gem, the
diamond. The three distinct and very dissimilar forms of
existence which this element assumes, give us one of the
best examples known of the allotropism of bodies. We will
very briefly mention the principal characters of the three
forms of carbon: 1. The diamond; 2. Graphite or plum-
bago; 3. Mineral coal and charcoal.
358. The diamond is pure carbon crystallized. It takes
the forms of the regular system, or first crystalline class,
-(44,) of which the annexed figures are some of the common
modifications. Its crystalline faces are often curved, as in
fig. 266. The diamond is the hardest of all known sub-
stances, and can be scratched or cut only by its own dust.
Pig. 265. Fig. 260. Fig. 267. Fig. 268. Fig. 269.
The solid angles of this mineral, formed by the union of curved
planes, are much used, when properly set, for cutting glass,
What of the bromids and sulphurate ? 357. Give the history of carbon.
What is its equivalent? What of its allotropism? 358. What of the
diamond ?
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CARBON. 217
-which it does with great ease and precision. It has a specific
gravity of 352, and the highest value of any kind of treasure.
The most esteemed diamonds are colorless, and of an inde-
scribable brilliancy, described as the " adamantine lustre."
They are often slightly colored, of a yellowish, rose, blue,
or green, and even black tint. The largest known dia-
mond formerly belonged to the Great Mogul, and when
found weighed 2769-3 grains, or nearly six ounces : it had
the form of half a hen's-egg. The Pitt,or Regent diamond,
was sold to the Duke of Orleans for £130,000. It weighs
less than an ounce. This was the gem which Napoleon
mounted in the hilt of his sword of state. The Koh-i-noor,
or mountain of light, (the Great Mogul diamond,) which
now belongs to Queen Victoria, was valued to the British
government at two million pounds sterling, but its com-
mercial value is about three millions of dollars, or £622,000.
It weighed before its recent cutting, 1108 grains, or 277
carats. This gem was found at Golconda. The diamond is
usually found in the loose sands of rivers, and is gene-
rally accompanied by gold and platinum. Its native rock
is supposed to be a peculiar flexible kind of sandstone,
called itacolumite; and it is sometimes found loosely
imbedded in a ferruginous conglomerate in Brazil. A few
diamonds have been found in the United States; chiefly
in North Carolina.
359. From its high refractive power the diamond is sup
posed to be of vegetable origin. The sun's light seems to be
absorbed by the diamond, since it phosphoresces beautifully
for some time in a dark place, after it has been exposed to
the sun. It is a non-conductor of heat and electricity, and
is very unalterable by chemical means. It is infusible,
and not attacked by acids or alkalies. But heated to redness
in the air, it is totally consumed, and the sole product of its
combustion is carbonic acid gas.
360. (2.) Graphite or Plumbago. — This form of carbon
is sometimes improperly called " black-lead" but it does not
contain a trace of lead in its composition, and bears no re-
semblance to it, except that both have been used to mark
upon paper.
This peculiar mine/al is found in the most ancient rocks,
Give its form and characters. What is its lustre ? What are some of the
highly valued diamonds ? What of Koh-i-noor ? Where is the diamond
found? 859. What of its supposed origin? 360. What is plumbago?
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218 NON-METALLIC ELEMENTS.
as well as with those of a more modern era. It is also fire*
quently found in company with coal, and is sometimes formed
artificially, as in the fusion of cast-iron. It almost always
contains a trace, and sometimes several per cent, of iron,
which is, however, foreign to it; otherwise it is pore carbon.
It is very much used for making pencils, and the coarser
sorts are manufactured into very useful and refractory melt-
ing pots. The most valued plumbago for the finest drawing
pencils has been brought chiefly from the Borrowdale mine,
in Cumberland, England; but it is a common mineral in
this country, as, for instance, at Stur bridge in Massachusetts,
St. John in New Brunswick, and many other places. It is
found crystallized in flat, six-sided prisms, a form altogether
incompatible with that of the diamond. It is soft, flexible,
and easily cut; its density is 2*20; feels greasy, and marks
paper. It is quite incombustible by all ordinary means, but
burns in oxygen gas, forming only carbonic acid gas, and
leaving a red ash of oxyd of iron.
361. (3.) Coal. — The vast beds of mineral carbon, known
as anthracite, bituminous coal, brown coal, and lignite, are
all of them nearly pure carbon. Of the first two of these,
no country has such abundant and excellent supplies as the
United States. These accumulations of fuel are the remains
of the ancient vegetation of the planet, which, long anterior
to the creation of man, a bountiful Providence laid away in the
bowels of the earth for his future use. Bituminous coal differs
from anthracite only in having a quantity of volatile hydro*
carbon united with it, which is wanting in the anthracite.
This opake combustible mineral is entirely a non-conductor of
electricity, and some of its varieties excite resinous electricity.
362. Charcoal from wood is the carbonized skeleton of
the woody fibre which is found in all plants. The best
charcoal is made by heating sticks of wood in tight iron
vessels, without contact of air, until all gases and vapors
cease to be given off. A great quantity of acetic acid, tar,
and oily matters, with water, are given out, and a jetty
black, brittle, hard charcoal is left behind, which is a per-
fect copy of the form of the original wood. It is a non-con-
ductor of heat, but conducts electricity almost as well as a
metal. It is a very unchangeable substance, insoluble in
Where found? What its character? 361. What of coal? What its
origin ? What difference between anthracite and bituminous ? What of
It* electrical character? 362. What is charcoal ? What its characters?
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CARBON. 219
water, acids, or alkalies, suffers little change from long ex-
posure to air and moisture, and does not yield to the most
intense heat to which it can be subjected, if air is excluded.
363. Charcoal has the property of absorbing gases to a
most remarkable degree, at common temperatures. A frag-
ment of recently heated charcoal, of a convenient size to be
introduced under a small air-jar over the mercurial cistern,
will soon take up many times its own volume of air, as will
appear by the rise of the mercury in the air-jar. In this
case it absorbs more oxygen than nitrogen, the residual air
having only eight per cent, of oxygen in it. On heating,
it again parts with the gas it has absorbed. The power of
absorption seems to depend entirely on the natural elasticity
of the gas, and not at all on its affinity for carbon. Those
gases that are most easily reduced to a fluid condition by
cold and pressure, are most abundantly absorbed by char-
coal. Charcoal from hard wood with fine pores has this
property in the highest degree. Thus, charcoal from box-
wood freshly prepared, will absorb of ammoniacal gas 90
times its own volume ; of muriatic-acid gas, 85 times ; of
sulphuretted hydrogen, 81 times ; of nitrous oxyd, 40 times;
of carbonic acid, 32 times ; of oxygen, 9-25 times; of nitro-
gen, 1*5 times; and of hydrogen, 1*75 times its own
volume.
364. Charcoal also has the power of absorbing the bad
odors and coloring principles of most animal and vegetable
substances. Tainted meat is made sweet by burying it in
powdered charcoal, and foul water is purified by being
strained through it The highly colored sugar-syrups are
completely decolorized by being passed through sacks of
animal charcoal, (bone-black,) prepared by igniting bones.
It also precipitates bitter principles, resins, and astringent
substances from solution. Common ale or porter becomes
not only colorless, but also in a good degree deprived of its
bitter principles, by being heated with and filtered through
animal charcoal. This property is lost by use, and regained
by heating it afresh. Its power of absorption seems similar
to that possessed by spongy platinum, (251.) Hydrogen,
in small quantity, is very obstinately retained in the pores
of charcoal, and water is consequently always produced from
363. What of its absorbing power? What regulates its power with
irions gases ? 364. What of its disinfecting and decolorising powers ?
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220
NON-METALTJO ELEMENT*.
the combustion of carbon in pure oxygen gas. Carbon bat
a greater affinity for oxygen at high temperatures than any
other known substance, and for this reason it is useful in
reducing the oxyds of iron and other oxyds to the metallic
state. Lamp-black is a pulverulent variety of carbon, pro-
duced from the imperfect combustion of oils and resins.
Compounds of Carbon with Oxygen.
365. The compounds of carbon, oxygen, and hydrogen
embrace a majority of the bodies described in the organic
chemistry ; which is therefore not improperly termed the
chemistry of the carbon series. We will consider at pre-
sent, however, only carbonic acid and carbonic oxyd.
366. Carbonic Acid, COa. — History, — This is the sole
product of the combustion of the diamond or any pure carbon
m the air, or in oxygen gas. It was first recognized and
described by- Dr. Black, in 1757, under the name of fixed
air. This philosopher proved that limestone and magne-
sian rocks contained a large quantity of this gas in a state
of solid combination with the earths, and also that it was
freely given out in the processes of fermentation, respira-
tion, and combustion.
367. Preparation. — Carbonic acid is easily procured by
treating any car-
bonate with a di-
lute acid. Car-
bonate of lime, in
the form of mar-
ble powder, is
usually employed
for this purpose: it
is put with a little
water into a two-
mouthed bottle A,
(fig. 270;) dilute
chlorohydric acid
is turned in at the
tube-funnel bf
when the gas is
Fig. 270.
What is lamp-black? 365. What of the compounds of C with
hydrogen, Ac.? 366. What is CO,? What was Black's discovery?
t67. How is COa prepared ?
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CARBON. 221
sot free with effervescence, and escapes through the bent tube
at a. Its weight enables us to collect it in dry bottles, by
displacement of air, as in the case of chlorine. It may
also be collected over water. No heat is required, and
the acid is added in small successive portions, the gas being
freely evolved at each addition. When obtained by the
action of monohydrated nitric acid on bicarbonate of am*
monia, the carbonic acid evolved retains a cloudy appear-
ance, even after passing through water, which renders it
visible — a point of some importance in experiments with
this gas.
36o. Prapertie*. — At the common temperature and pres-
sure, carbonic acid is a colorless, transparent gas, with a
pungent and rather pleasant taste and odor. At a tem-
perature of 32°, and a pressure of 30 to 36 atmospheres, it is
Condensed into a clear limpid liquid, not as heavy as water,
which freezes by its own evaporation into a white, snow-like
substance. Wc have already described (151) the apparatus
and process by which this interesting experiment is per-
formed. Carbonic acid is about once and a half as heavy
as common air, having a specific gravity of 1-529 ; and 100
cubic inches therefore weigh 47*26 grains. Owing to its
weight, it may be poured from one
( vessel to another, (fig. 271.) Car-
bonic acid instantly extinguishes
a burning taper lowered into it,
even when mingled with twice
or three times its bulk of air.
Burning sulphur and phosphorus
are also immediately extinguished
in this gas. Potassium, however,
quite clean, may be burned in a
Florence flask filled with dried
carbonic acid; the potassium is
ignited by application of heat, and
Fig. 271. tne carbon is then deposited on
Che glass vessel. Fresh lime-water agitated with this gas,
rapidly absorbs it, becoming at the same time milky, from
the production of the insoluble carbonate of lime; soluble,
however, in excess of carbonic acid. In this way the pre-
868. What its properties ? What its density ? How does it affect com-
bustion ? How is it decomposed ?
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222 NON-MITALLIC ELEMENTS
sence of carbonic icid in the atmosphere is easily detected,
and this gas is distinguished from nitrogen by the same
test.
369. Cold water recently boiled absorbs rather more than
its own volume of carbonic acid gas, but with pressure
more will be taken up, in quantity exactly proportioned
to the pressure exerted. The solution has a pleasant acid
taste, and temporarily reddens blue litmus paper. The
"soda water/' so much used as a beverage, is usually only
water strongly impregnated with carbonic acid, the soda
being generally omitted in its preparation. The efferves-
cence of this, as well as of small beer and sparkling wines,
is due to the escape of this gas. Natural waters have
usually more or less of this gas dissolved in them; and some
mineral springs, like the Saratoga and Ballston springs,
and the Seltzer water, are highly oharged with carbonic
acid.
370. Death follows the inspiration of carbonic acid,
even when largely diluted with air. It kills by a specific
poisonous influence on the system, resembling some narco-
tics, and is unlike nitrogen in this particular, which
kills only by exclusion of air. Instances of death from
sleeping in a close room where a charcoal fire is burning, and
from descending into wells which contain carbonic acid, are
lamentably frequent. The latter accident may be avoided
by taking the obvious precaution to lower a burning candle
into the well before going into it, when if the candle burns
with undiminished flame, all may be considered safe, but
its being extinguished is certain evidence that the well is
unsafe. Wells containing carbonic acid may often be freed
from it by lowering a pan of recently-heated charcoal into
the well, which will soon absorb thirty-five times its bulk
of this gas, (368,) thus removing the evil. Even so small
a quantity of carbonic acid as 1 or 2 per cent, produces, after
some time, grave effects on respiration. Small animals
thrown into a vessel full of this gas, may be recovered by im-
mersion in cold water. The so-called Black Hole of Calcutta
is a noted instance of the fatal effects of respiring an atmo-
sphere overcharged with carbonic acid.
369. What of its solution in water? 370. What is its effect on life !
Where do accidents often happen ? How prevented ? What quantity
is injurious ?
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/
OABBON.
228
371. Numerous natural sources evolve large quantities of
carbonic acid, particularly in volcanic districts. The Grotto
del Cane, in Italy, (dog's grotto,) is a well-known example
of the natural occurrence of this gas. But the quantity
evolved there is trifling compared to that, which escapes
constantly from Lake Solfatara, near Tivoli, whose surface ia
violently agitated with the gases boiling through it.
It is always present in the air, being given off by the
respiration of all animals; and, besides the other sources
already named, is an invariable product of all common
cases of combustion.
All the carbon which plants secrete in the process of
their development, is derived either from the carbonic acid
of the atmosphere, which they decompose by the aid of
sunlight and their green leaves, retaining the carbon and
returning the pure oxygen to the air ; or it is absorbed by
their rootlets, and then decomposed by the sun's light at the
surface of the leaf.
372. Carbonic acid is formed of equal volumes of its
two constituent gases, condensed into one. For this rea-
son the air suffers no change of bulk from the enormous
quantities of this gas which are hourly formed and decom-
posed on the earth. This acid unites with alkaline bases,
forming an important class of salts, (the carbonates,) which
are decomposed by even the vegetable acids, with the escape
of carbonic acid.
373. Carbonic Oxt/d, CO. — Preparation. — TMa *
is most easily
obtained from
oxalic aoid.
This acid, when
treated with
five or six times
its volume of
sulphuric acid,
in the flask a,
<;fig. 272), is
decomposed,
yielding equal
volumes of car-
Fig. 272.
3T1. What sources are named for it ? How in the air ? Whence the car-
bon of plants ? 372. What is its constitution ? What are its salts called f
373. How is CO prepared ? What of oxalic acid ? *
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224 NON-MITALLIO ELEMENTS.
bonio add and carbonic oxyd. Thus, C908+HO— C08+C0,
the water remaining with the sulphuric acid. The carbonio
acid is easily removed by a solution of caustic potash in the
wash-bottle o. Dry, finely-powdered, yellow prussiate of
potash, when decomposed by ten times its weight of sulphuric
acid, in a very capacious vessel, yields an abundant volume
of pure oxyd of carbon.
374. Properties. — This is a colorless, almost inodorous
gas, burning with a beautiful pale-blue flame, such as is
often seen on a freshly-fed anthracite fire. Its specific gravity
is a little less than that of air, or -967 ; and 100 cubic
inches of it weigh 30*20 grains. Water absorbs about ^9
of its volume of it; it does not render lime-water milky,
and explodes feebly with oxygon. It is not respirable, but
is even more poisonous than carbonio acid, producing a
state of the system resembling profound apoplexy. This
gas is very largely produced in the process of reducing iron
from its ores in the high furnace.
Carbonic oxyd is formed of half a volume of oxygen,
and one volume of carbon, or two volumes of carbon and
one of oxygen, condensed into two volumes.
375. Chloro-carbonic oxyd is formed of equal volumes of
chlorine and oxyd of carbon. This union with chlorine is
produced . by the influence of light, and hence the product
was called phosgene gas. This is a pungent, highly odorous,
suffocating body, possessing acid properties, and decomposed
by water. Its formula is CO. CI, or carbonio acid in which
chlorine occupies the place of an atom of oxygen. Its
density is 3-407.
Compounds of Carbon with the Chlorine Chroup.
The chlorids of carbon will be described in the organic
chemistry.
376. Bisulphuret of Carbon, C.Sa. — This remarkable
product is formed by the direct union of its elements.
In a retort of fire-clay C, (fie. 273,) fragments of charcoal
are placed. A porcelain tube b descends nearly to the
bottom of the retort, being luted with clay at a. When
the retort is red hot, small bits of roll sulphur are from
374. What are the properties of CO? 375. What is chloro-carbonk
oxyd ? 376. How is biiulphuret of carbon prepared in fig. 273 ?
Digitized by VjOOQ IC
CARBON.
225
Fig. 273.
Fig. 274.
time to time dropped in at b, and
this orifice immediately closed by
a cork. The vapor of sulphur rising
among the ignited carbon combines
with it, and bisulphuret of carbon
distills, is con-
densed by a
refrigerating
tube,(fig.274,)
and collected
in the bottle
surrounded by
cold water, o.
The first pro-
duct is yellow, from free sulphur, and is
purified by a seoond distillation. When
pure, bisulphuret of carbon isacolorless,
very mobile and volatile fluid, with a
disgusting odor, altogether peculiar. Its
density at 32° is 1-293 ; at 60°, 1-271.
It boils at 110°, and its vapor has a
density of 2-68. Its power of refracting light is very remark-
able. It dissolves sulphur, phosphorus, and iodine, these bodies
being deposited again in beautiful crystals by the evapora-
tion of the sulphuret of carbon. G-utta percha and India*
rubber are also soluble in it. It burns in the air at about
600°, with a pale blue flame, producing carbonic and sul-
phurous acids. It forms an explosive mixture with oxygen,
and a combustible one with binoxyd of nitrogen. It dis-
solves easily in alcohol and ether, and is precipitated again
by water.
Carbon with Nitrogen.
377. Cyanogen, C9N or Cy. — This important and in-
teresting compound of carbon and nitrogen belongs appro-
priately to the organic chemistry ; but it deports itself so
much like an elementary substance and its compound with
hydrogen, (cyanhydric or prussic acid,) and its metallic
compounds also, are of so much general interest, that it is
proper to mention this compound-radical here.
What are its properties? What its solvent powers? 877. What%of
cyanogen ? Giye its formula.
16
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228 NON-METALLIO ELEMENTS.
Carbon and nitrogen combine only indirectly. If car-
bonate of potassa and carbon are heated together in a por-
celain tube, while nitrogen is passing over them, oxyd of
carbon escapes, and cyan id of potassium in considerable
quantity remains in the tube, and may be dissolved out by
water. Cyanogen is usually prepared in the laboratory, by
decomposing cyanid of mercury (CyHg) in a small retort
by heat, ana collecting the gas over mercury. It is more
economically and abundantly prepared, however, by healing
a mixture of 6 parts of dried ferrocyanid of potassium, and
9 parts of bichlorid of mercury in a flask of hard glass. The
cyanid of mercury formed is decomposed immediately into
mercury and cyanogen.
378. Properties. — Cyanogen is a colorless gas, of a strong
and remarkable odor, resembling peach-pits. Its density
'A 1*86. At a temperature of — 4°, it is liquefied, and at
common temperatures, with a pressure of 4 or 5 atmo-
spheres. Liquid cyanogen is a colorless, very mobile fluid,
whose density is about 0 9. By keeping a short time, it
undergoes a change, becomes brown, and deposits a brown
powder in the glass. This is paracyanogen, an isomeric
form of cyanogen, a portion of which is always seen as a
residue in the retort after decomposing cyanid of mercury.
Cyanogen burns with a magnificent and characteristic
purple flame, giving carbonic acid and free nitrogen. For
this purpose a large vessel may be filled with the gas, by
displacement. Water dissolves 4 or 5 times its volume of
cyanogen, and alcohol 24 or 25 times its volume. Cyanogen
forms cyanids — compounds almost exactly analogous to the
chlorids of the same metals, and in which cyanogen com-
ports itself like an element.
Cyanogen is formed from 1 volume of carbon vapor, weighing 0*8290
and 1 volume of nitrogen " 0*9713
1*8003
which is a close approximation to 1-86, the result of ex-
periment.
How do C and N unite ? How is Cy usually prepared ? How from
bichlorid of mercury and ferrocyanid of potassium ? 378. What are its
properties ? How liquefied ? How does the liquid change ? How does
Cy burn ? What compounds does it form ? Analogous to what ? What
is its volume composition ?
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silicon. 227
SILICON.
Equivalent, 21*3. Symbol, Si. Density in vapor, (hypo*
thetical,) 15 29.
379. Silicon combined with oxygen, forming silica, is
abundantly distributed throughout the earth. It is said to
form ith part of the crust of the globe.
Silicon is prepared by decomposing the double fluorid of
silicon and potassium by metallic potas-
sium. The potassium, in small pieces,
is mingled with £th its weight of the
dry white powder of .the double fluorid,
in a test-tube, (fig. 275,) which is then
heated. Reaction occurs as soon as
the bottom of the tube is red, and
spreads through the whole mass. The
«ool residue is treated with water,
which dissolves the fluorid of potas- lg*
sium, and leaves silicon. Thus,
3KF.2SiF8+6K = 9KF+2SL
380. Properties. — Silicon is a nut-brown powder, and a
non-conductor of electricity. Heated in air or oxygen it burns,
forming silica. If heated in a close vessel, it shrinks, and
becomes more dense. Before ignition it is soluble in hydro-
fluoric acid, but after this it is insoluble, and is incombustible
in the air or oxygen gas. It seems then to resemble the
graphite variety of carbon. These two diverse conditions
of silicon are probably connected with the two states in which
silica occurs.
381. Silicic acid, or silica, SiOs, is far the most import-
ant of all the compounds of silicon. It exists abundantly
in nature, in the form of rock crystal, agate, common un-
crystallized quartz, silicious sand, &c. ; it also enters largely
into combination with other substances to form the rock
masses of the globe. It is a very hard substance, easily
scratching glass, and is difficult to reduce to a powder ; its
specific gravity is 2 -66. Its usual crystalline form (fig. 276) is
a six-sided prism, with two similar pyramids. It is infusible
379. What of silicon ? Give its equivalent. How is it prepared ? 6iv«
the reaction. 380. What are its properties? What two States? 381.
What is silica?
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228 NON-METALUO ELEMENTS.
«&.
V
alone, except by the power of the compound blow*
pipe. It dissolves with effervescence in fluohydrie
acid and in fused carbonate of soda or potash. No
acid, except the hydrofluoric, has any effect on silica.
When in its finest state of division it is still harsh
Fig/276, and gritty to the touch or between the teeth.
382. When silica is fused in 4 or 6 times its weight of car-
bonate of soda or potassa, and this mass is treated with a
large volume of dilute chlorohydric acid until it manifests a
decidedly acid reaction, the silica after some time separates
as a transparent, tremulous jelly. This is soluble hydrated
silica. If dried, it again becomes gritty and insoluble as
before. Most natural waters contain some small portion of
soluble silica; it has often been seen in this state in mines;
and on breaking open silicious pebbles, the central parts are
sometimes semifluid and gelatinous. The hot waters of the
great geysers in Iceland, and of other hot springs, also dis-
solve large quantities of silica, probably aided by alkaline
matter. Agates, chalcedony, carnelian, onyx, and similar
modifications of silica have been deposited from the soluble
state. It is in this condition, no doubt, that silica enters
the substance of many vegetables, as, for instance, the reeds
and grasses, which have often a thick crust of silica on their
bark. It is in this form also that silica acts as the agent of
petrifaction.
383. The acid powers of silica are seen only at high tem-
peratures, when it saturates the most powerful alkalies and
displaces other acids, forming silicates. Hence its great use in
the art of glass-making, as it is the basis of all vitreous
fabrics, including porcelain and potters1 ware, which are all
silicates. Soluble glass is formed when an excess of alkali
is employed; and liquor of flints is an old term applied to a
solution of silicate of potassa or soda.
384. Chlorine, bromine, fluorine, and sulphur, all form
compounds with silicon, having the formula 8iKa, or exactly
the formula for silica. The chlorid of silicon is formed by
passing dry chlorine over a mixture of fine silicious sand
and charcoal in a porcelain tube heated to redness. It is a
colorless, mobile liquid, having a density of 1-52, and boil-
ing at 138°. It is decomposed by water into silica and
What its forms in nature ? 382. When fused with alkali, how is it
separated ? How does it exist in water and plants ? 383. What of its
acid powers ? 384. What does S form with class II ? What of its chlorid f
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BORON.
229
•hloroh ydri J acid. Bromid of silicon is formed in a similar
manner.
385. Fluorid of Silicon, (flito-silicic acid,') may be pre-
pared by heating sulphuric acid with fluor-spar in powder, to
which is added twice its own weight of fine silica or powdered
glass. The apparatus should be quite dry :
Fluorspar. Silica. Sal. Acid. Sal. Lime. Water. Fluorid Silicon.
8CaF + SiO, + 8(SO,.HO) = 3(CaO.SOt) + 3HO + SiF,.
Fluorid of silicon is a colorless gas, irrespirable, and de-
composed by water. Its density is 3*57. It forms dense
white vapors in contact with the moisture of the air. Passed
into water it is immediately decomposed, gelatinous silica is
precipitated, and the water becomes a solution of hydro-fluo-
hi licic acid. The reaction is
3SiF8+3HO=3HF.2SiF8+Si08.
The fluorid of silicon should not pass directly into the
water from the gas tube, but
into some mercury on which
the water rests, as in fig.
277. If this precaution be
neglected the open end of
the gas tube will become
plugged with deposited sili-
ca. The silica obtained in
this operation, when well
washed, is quite pure. The
hydro-fluosilicic acid forms
an insoluble salt with potas-
sium 3KF.2SiF,. Fig. 277.
Equivalent, 10-90.
BORON.
Symbol, B. Density in vapor, (hypo*
thetical,) -751.
386. Boron is known chiefly by its compounds, borax and
boracic acid. Boracic acid is found in nature, either free
or combined with various bases ; but it is rather a rare sub-
stance. Boron is prepared by heating the double fluorid of
385. What is its fluorid ? Give the reaction by which it is produced ?
What its characters? How does water affect it? What is hydro-fluosili-
eic acid ? Explain its production as in fig. 277. 386. What is boron ?
How distributed in nature ? What its equivalent?
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230 NON-METALLIO ELEMENTS.
boron and potassium in an iron vessel, with potassium, an
in case of silicon. Boron is a dark olive-green powder.
Heated to 600° in air it burns brilliantly, forming boracio
acid. It does not conduct electricity, and is insoluble in
water. Heated out of contact of air it suffers no change.
387. Boracic Acid, BOs, is exhaled from volcanic vents,
as in Vulcano, one of the Lipari Islands, and also more
abundantly in the Tuscan maremma, not far from Leghorn.
There it issues, accompanied by jets of steam, from the soil.
These jets have been carried into lagoons of water constructed
around them, where the boracic acid is taken up by the
water. The heat of the earth affords the means of evapo-
rating the water. Figure 278 shows one of these masonry
basins, 0, built around the jets, Qsvffoni.) A series of
these, four or five in number, are arranged one above the
other: the least concentrated solutions occupy the upper
basin, and are in turn, once in twenty-four hours, drawn off
to- the lower, and finally to the evaporating pans E F, also
heated by the escaping steam from the earth. In this man-
ner the solution is brought to crystallize, and is purified by
repeated crystallization. The production of boracic acid from
this source equals two millions and a half pounds per year.
Fig. 278.
388. In the laboratory, boracic acid is obtained by de-
composing borax of commerce. For this purpose, one part
of borax is dissolved in two and a half parts of boiling water,
and chlorohydric acid added until the liquid is strongly acid.
On cooling, the boracic acid crystallizes in elegant tufts of
scaly crystals, and is purified by a second crystallization.
Boracic acid is a white pearly substance in thin scales : these
have a feeling like spermaceti, are feebly acid to the taste,
and soluble in twelve parts of boiling and in fifty parts of
387. How is BO, found ? Describe the Tuscany lagoons. How are
they heated? Whence the B03? 388. How is BO, prepared in the
laboratory ? What are its properties ?
Digitized
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HYDROGEN. % 281
cold water. A boiling saturated solution deposits fths of its
acid on cooling. The crystals contain 43 per cent, of water.
By heat it fuses in its crystallization-water, which is finally
expelled, and the acid, when heated to redness, fuses to a
clear glass, which may be drawn out in fine threads. This
glassy acid loses its transparency by keeping for some time.
Boracic acid is a feeble acid in solution, but it expels sul-
phuric acid from the sulphates at a red heat and forms glass
with oxyds of lead and bismuth, of very high refractive
powers. Alcohol dissolves boracic acid, and the solution,
when set on fire, burns with a peculiar green flame, charac-
teristic of boracic acid. Hydrous boracic acid is volatile by
vapor of water, but the glassy acid is quite fixed at the
highest temperatures. Boracic acid and the borates are
much used as fluxes, to promote the fusion of other bodies.
389. Cfdorid of Boron, BC18, is formed in the same man-
ner as chlorid of silicon. It is a colorless gas of a specific
gravity of 4 09, decomposed by water into chlorohydric and
boracic acids.
390. Fluorid of Boron, BF8. — This gas is obtained when
we heat together 2 parts of fluor-spar and 1 part of fused
boracic acid in a vessel of porcelain at redness. 7BO.+
3CaF=3(Ca02B08)+BFa. It is a colorless, suffocating
gas, strongly acid, very soluble in water, and exceedingly
greedy of it, so that it even carbonizes organic substances to
obtain it, in the manner of sulphuric acid. Water dissolves
700 or 800 times its volume of this gas.
If fluor-spar, boracic acid, and concentrated sulphuric
acid are heated together in a glass retort, a gas of a brownish
color, very acid, and breaking on the. air in white fumes, is
obtained : this is hydro-fluoboracic acid. It must be collected
over mercury.
CLASS VI.
HYDROGEN.
Equivalent, 1. Symbol, H. Density, 0-0692.
391. History. — Hydrogen was first described as a dis-
tinct substance by the English chemist Cavendish, in 1766,
and was called by him inflammable air. It had previously
What dissolves it? What is characteristic of BOt? How does heat
affect it? 389. What of BC1. ? 390. What of fluorid of boron ? What
of its properties ? 391. What is the history of hydrogen ? Its equivalent?
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NON-METALLIO ELEMENTS.
been confounded with other combustible gases, several of
which had been long known. Hydrogen exists abundantly
in nature as a constituent of water, and also of nearly all
animal and vegetable substances, in such proportions as to
form water when these bodies are burned. It is named
from the Greek httdor, water, and gennao, I form.
892. Preparation. — This gas is generally prepared by
the action of dilute sulphuric acid on zinc or iron. Zinc is
usually preferred. The acid is diluted with four or five
times its bulk of water, and the operation may be conducted
Fig. 279.
in a glass retort, or more conveniently by using a gas-
bottle a, (fig. 279,) containing the zinc in small fragments,
to which the dilute acid is turned through the tube-funnel
b. The shorter tube /, with a flexible joint, conveys the
gas to the air-jar standing in the cistern g. No heat is re-
quired in this operation. An ounce ot
zinc yields 615 cubic inches of hydro-
gen gas. Zinc is readily granulated,
by being turned, when melted, into
cold water. When hydrogen is re-
' quired in large quantity, a leaden pot
or stone jar, properly fitted, and hold-
ing a gallon or more, is used to contain
the requisite charge of materials, and the gas is stored for
use in a gas-holder, or India-rubber bag, (fig. 280,) (281.)
393. The reaction in this case is between the zinc and
Fig. 280.
How does it exist ? 392. How is it prepared and stored ? 393. What
Is the reaction ?
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HYDROGEN. 233
Hie sulphuric acid, the hydrogen of the latter being replaced
by the zinc, thus: SO,.HO+ Zn = S08.ZnO+H.
If ohlorohydric acid had been used, the reaction is still more
simple, thus: HCl-f-Zn = ZnCl-f-H. .
Water is essential to the rapidity of the action, by dissofv
ing the sulphate of zinc, which is insoluble in strong sulphu-
ric acid, and unless removed, immediately arrests the process.
394. Hydrogen gas,
when obtained from
iron, has a peculiar and
offensive odor, due to
the presence of a vola-
tile oil formed from
the carbon always pre-
sent in iron. That pro-
cured from zinc is
also somewhat impure.
Traces of sulphuretted 'nrrr ^T
hydrogen and carbonic
acid are usually found in hydrogen, from impurity in the
metals employed ; and also a trace of both iron and zinc is
raised in vapor, and gives color to the flame of common
hydrogen. Most of these impurities are removed by pass-
ing the gas through a second bottle d, (fig. 281,) containing
an alcoholic solution of caustic potash. Water only, in d,
removes the vapor of acid found usually in the gas.
395. Properties. — Hydrogen is a colorless, inflammable
gas : it has never been liquefied. It refracts light very pow-
erfully, and has the highest capacity for heat of any known
gas. It is, when quite pure, inodorous and tasteless, and
may be breathed without inconvenience when mingled with
a large quantity of common air. The voice of a person who
has breathed it acquires for a time a peculiar shrill squeak.
It cannot, however, support respiration alone, and an animal
plunged in it soon dies from want of oxygen. Water ab-
sorbs only about one and a half per cent, of its bulk of pure
hydrogen gas. Sounds are propagated in hydrogen with
but little more power than in a vacuum.
Hydrogen is the lightest of all known forms of matter,
How is water necessary to it? 394. What renders it impure ? How
Is it purified ? 395. What are the properties of hydrogen ? How as re-
speots respiration ?
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284 NON-METALLIO ELKMENT8.
being sixteen times lighter than oxygen, and fourteen times
and a half lighter than common air. 100 cubic inches of it
weigh only 2*14 grains. Soap-bubbles blown with it rise
rapidly in the air ; and it is often employed to fill balloons
in absence of the cheaper coal gas. A turkey's crop, well
cleansed, makes a good balloon on a small scale, for the
class-room, and very beautiful small balloons (from 1} to 5
feet diameter) are prepared in Paris of gold-beaters' skin.
396. Hydrogen is the most attenuated as well as the
lightest form of matter with which we are acquainted. We
have reason to suppose the molecules of this body to be
smaller than those of any other now known to us. Dr.
Faraday, in his attempts to liquefy hydrogen, found that it
would leak freely with a pressure of 27 or 28 atmospheres,
through stopcocks that were perfectly tight with nitrogen
at 50 or 60 atmospheres. This extreme tenuity, together
with the remarkable law of diffusion of gases
already explained, (147,) renders it unsafe to
keep this gas in any but perfectly tight ves-
sels. A small crack in a bell-jar, quite too
narrow to leak with water, will soon render
the hydrogen with which it may be filled ex-
plosive. The superiority in diffusive power
which hydrogen has over common air, is well
seen in what is called Mr. Graham's diffusion
tube, of which a figure is annexed. A glass
tube, 11 or 12 inches long, (fig. 282,) and of
convenient size, has a tight plug of dry plaster
___ of Paris at the upper end, and being filled
Fie. 2a2. w^ ^rv hydrogen by displacement of air, and
its lower end put into a glass of water, the
hydrogen escapes so rabidly through the plaster plug, that
the water is seen to rise in the tube, so as in a few mo-
ments to replace a considerable portion of the hydrogen, and
the remaining portion of gas is found to be explosive.
Hydrogen also enters into combination in a smaller propor-
tionate weight than any known body, (238,) and consequent-
ly has been chosen as the unit of the scale of equivalents.
What of its density ? What the weight of 100 cubic inches ? What
nse is made of its levity ? 396. What is the tenuity of hydrogen ? Gire
Ulustrations from Faraday ? What is Graham's diffusion tube ? What
of the atomic weight of hydrogen ? Why has it been adopted as unity ?
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HYDROGEN.
285
807. Hydrogen is a most eminently combustible gas, tak.
ing fire from a lighted taper, which is instantly extinguished
by being plunged into the gas. It burns with a bluish-white
flame and a very faint light. A drj bottle with its mouth
downward (fig. 283) is well suited to collect this gas by dis-
placement of air, as the heavier gases are collected
by the reverse position. When lighted, the gas
burns quietly at the mouth of the bottle; and
the extinguished taper may be relighted by the
flame at the mouth. If the bottle is suddenly re-
versed after the gas has burned awhile, the remain-
ing gas, being mixed with common air, will burn
rapidly with a slight explosion. Three of the most
remarkable properties of hydrogen are thus shown
by one experiment, viz. its extreme levity, its
combustibility, and its explosive union with oxygen.
If this gas is incautiously mingled with common
air, or much more, with pure oxygen, a severe ex-
plosion results when the mixture is fired. The g'
eyes or limbs of inexperienced operators have thus too often
paid the forfeit of carelessness by the explosion of glass ves-
sels. Particular caution is required not
to employ any gas until all the common
air is expelled, as well from the gene-
rator, as from the receiving-vessel or gas-
holder.
398. Water is the sole product of the
combustion of hydrogen. The production
of water from this combustion, and cer-
tain musical tones, are neatly shown by
an arrangement like fig. 284. The gas is
generated in the bottle a, and a perforated
cork at the mouth has a small glass tube,
from the narrow end of which the stream
of hydrogen is lighted. An open glass tube
Fig. 284. ^ about two feet long, held over this flame,
is at once bedewed by the water produced in the
combustion, and a musical tone is also generally
heard. This arises from the interruption which the
flame suffers from the rapid current of air ascendiDg g*
397. Give illustrations of its combustibility. What happens if it ii
mixed with air? What caution is required? 398. What is the produot
•f its combustion ? What happens if it is burned from a jet in a tuba ?
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NON-METALUO ELEMENTS.
through the tube, causing it to flicker, and being moment*
arily extinguished, there occur a series of little explosions,
so rapid as to give a tone. The pitch of the note produced,
depends on the length and size of the glass chimney (fig.
285) and the size of the jet of hydrogen, which should be
small. If the jet is fitted to the gas-holder, we can modulate
the tone by regulating the supply of gas with the stopcock.
The little gas bottle (fig. 284) is often called the "philoso-
pher's lamp."
Compounds of Hydrogen with Oxygen.
899. There are two known compounds of hydrogen with
oxygen, viz. :
Water (the oxyd of hydrogen) HO
Binoxyd of hydrogen HOt
The first of these is the most remarkable compound known,
whether we contemplate it in its purely chemical relations,
or in reference to the wants of man and the present condition
of the globe.
400. Water. — The student has already become familiar
with the composition of water, as formed by the union of
two volumes of hydrogen and one of oxygen. In examining
the compounds of hydrogen and oxygen, as in all other
chemical investigations, we can pursue the subject either
analytically or synthetically; that is, we can either form the
compounds by the direct union of the elements, or we can
decompose these compounds, and thus gain a knowledge of
their constitution.
The simplest case of the decomposition of water is that
where metallic potassium, or sodium, is employed. The
potassium, from its great affinity for oxygen,
takes it from the water, (fig. 286,) and the
hydrogen escaping, is burned. If sodium is
introduced into an inverted test-tube under
"' 0jT water, the hydrogen is collected. The reao-
Flg* 286' tion is K+HO=KO+H.
401. The voltaic decomposition of water (224) is, however,
by far the most satisfactory experiment to this point which
IIow is this explained ? 399. What compounds does hydrogen form
with oxygen? 400. What of the constitution of water? What is the
simplest case of its decomposition ? Hew does potassium effect this ?
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COMPOUNDS OF HYDROGEN.
287
Fig. 288.
we possess, since both ele-
ments of the water are
evolved in a pure form
and in exact atomic pro-
portions by volume and
weight, (fig. 287.) In fact,
this is a complete experi-
mentum crucis, being both
analysis and synthesis; for
+we may so arrange the
single tube apparatus (fig.
288) that the mixed gases
Fig. 287. from the electrolysis of
water may be fired by an electric spark,
as soon as a sufficient volume of the '
mixture has been collected. A complete
absorption follows the explosion, and
the gases again go on collecting. Platinum, heated very
hot, decomposes water, and both gases are evolved: this
happens when vapor of water is passed through a tube of
platinum heated .to intense whiteness.
402. What potassium and sodium accomplish at ordinary
temperatures, is accomplished by iron, only at a red heat.
The experiment figured in fig. 289 was devised by Lavoisier :
an iron tube, (as a gun-
barrel,) or better a tube
of porcelain, protected by
an exterior tube of iron,
heated in a furnace to full
redness. The tube contains
clean turnings of iron, or
better a bundle of clean
iron wire of known weight.
A small retort a, holding a Fig. 289.
little water, is boiled by a spirit-lamp at the moment when the
tube is at a full red-heat : the vapor of the water coming into
contact with the heated iron is decomposed, the oxygen is
retained by the iron, forming oxyd of iron, and the hydro-
gen is given off from the tube /, which may be made to
conduct it to the pneumatic trough. For every eight
401. What of the voltaic decomposition of water ? How does platinum
decompose water? 402. Describe Lavoisier's experiment, fig. 289. What
becomes of the oxygen ?
Digitized
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288 NON-MITALLIC ELEMENTS.
grains of weight acquired by the iron, 46 cubic inches of
hydrogen, weighing one grain, have been evolved.
403. The iron in this case is evidently substituted for the
hydrogen, taking its place with the oxygen to form the oxyd
of iron, while the hydrogen is set free. The oxyd of iron
resulting from this action, is the same black oxyd which the
smith strikes off in scales under' the hammer, being a mix-
ture of protoxyd and peroxyd. This case of affinity is an
interesting one, because it is seemingly reversed when, under
the same circumstances, we pass a stream of hydrogen over
oxyd of iron. The iron is then reduced to the metallic state,
and water is produced. It will be remembered that we cited
this instance (270) while speaking of the influence of quantity
of matter in determining the nature of the chemical changes
which might take place among bodies.
Referring to the case (393) of sulphuric or chlorohydrio
acids and zinc, we cannot fail to observe the similarity of
the two cases of decomposition. That water, or the oxyda-
tion of a base, is not essential to the evolution of hydrogen
is conclusively shown in the case of dry chlorohydrio acid
(HC1) and zinc, which evolve hydrogen, when no compound
containing oxygen is present: HCl+Zn=ZnCl+H.
404. Zinc and iron do decompose water even without the
aid of an acid, but only with great slowness, and the action
ceases as soon as the metal is covered by the coating of the
oxyd thus formed, which protects it from further corrosion.
A dilute acid removes this coating of oxyd, and also aids,
no doubt, in establishing such electrical relations as to make
the zinc highly electro-positive. That this is the fact seems
quite probable, because pure zinc is hardly affected by dilute
acids, and we have already noticed the effects of amalgama-
tion (191) in rendering the zinc incapable of decomposing
water.
Much mystery formerly hung over this case of chemical
action, which is quite cleared away by the view now pre-
sented. It was formerly said that the presence of an acid
in water with zinc disposed the zinc to decompose the water.
This is what was meant by " disposing affinity/' But there
can be no oxyd of zinc to exert this influence on the acid,
403. Wbat is tbe theory of the process ? Why is this an interesting
ease of affinity ? What similarity is noticed with a previous case ? 404.
Wbat of the slow decomposition of water by zinc ? What view was held
formerly? What of disposing affinity?
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COMPOUNDS OF HYDROGEN. 289
Until the water is decomposed ; so that the idea that the
acid disposed the zinc to decompose the water is quite futile.
405. The real nature of hydrogen was for a long time
not well understood. It was associated with oxygen and
chlorine, because it was supposed to bear the same relations
to chlorohydrio acid, that oxygen bears to sulphuric and
ahloric acids. It is now known that hydrogen is most closely
allied to the metals, particularly to zinc and copper ; that
the chlorids, iodids, and fluorids of hydrogen, although they
possess the characters which we assign to acids, resemble in
many respects the chlorids, iodids, &c., of the same metals;
that in met, hydrogen is a metal exceedingly volatile, proba-
bly standing in that respect in the same relation to mercury,
that mercury does to platinum, but still possessed of all truly
chemical peculiarities of the metallic state, and no more
deprived of the commonplace qualities of lustre, hardness,
or brilliancy, than is the mercurial atmosphere which fills the
apparently empty space in the barometer tube. (Dr. Kane.)
The vapor of mercury, and of other volatile metals, is, like
hydrogen, a non-conductor of heat and electricity; but we
cannot on this account deny their metallic character. We
must not forget, moreover, that hydrogen may yet, by suffi-
cient cold and pressure, be made fluid or solid, when doubt-
less we shall see its resemblance in physical, as well as we
now do in chemical characters, to the metals. The propriety
of assigning to hydrogen the place in our classification which
it occupies, will thus be more apparent to those who have
usually seen it placed next to oxygen.
406. *A mixture of oxygen and hydrogen gases will never
unite under ordinary circumstances of temperature and pres-
sure ; but the passage of an electric spark through them, or
the application of red-hot flame, or an intensely heated wire,
will produce an explosive union, destructive to the contain
ing vessel, unless the gas is in extremely small quantities.
The re*composition or synthesis of water, was proved in tho
experiment in t he-single cell decomposing apparatus, (fig.
288.) If that explosion had taken place in a dry vessel over
mercury, the interior would have been bedewed with moisture
from the regenerated water. This may be done, as in fig.
405. What is said of the real nature of hydrogen ? What reasons exist
for supposing it a metal ? 406. How is the union of hydrogen and oxygan
•ffected?
Digitized
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240
NON-METALLIC XLXMINT8.
290, where a strong glass tube
t is divided into equal parts,
for convenience of measuring,
and supported firmly in the
mercury vase v. An electrical
spark from the Leyden vial I is
made to pass through the gas-
eous mixture by means of the
platinum wires p soldered into
the walls of the upper part of
the tube. Such an arrange-
ment is an eudiometer, some
allusion to which was made in
832. Hydrogen furnishes us
the most convenient means of
analysis of gases containing
oxygen, by combining with it
to form water. In eudiometri-
cal analysis it is always from
the volume that the result of
the analysis is deduced, and not,
Fig. 290. ag jn cagQ 0f solids, from the
weight A very good form of eudiometrical tube is that of
Dr. Ure, (fig. 291.) It is a graduated tube, closed as before
at one end, and bent on itself. When used,
it is filled with dry mercury, by placing
it horizontally in the mercury trough. A
portion of the gaseous mixture to be de-
> tonated is then introduced, the thumb
placed over the open end, and all the mix-
ture adroitly transferred to the closed limb.
The mercury is made to stand at the same
level in both limbs, by forcing out a por-
tion with a glass rod thrust in at the full
side. These adjustments being made, the
whole bulk of the mixture is read on the
graduation, and while the thumb is firmly
held over the open end of the tube, an
electrical spark is made to explode the
Fig. 291. eases. The air between the thumb and
Describe fig. 290. How is hydrogen useful in gas analysis ? What if
lire's eudiometer? How is it used?
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COMPOUNDS OF HTDBOOEN.
241
die mercury acts like a spring to break the force of the ex-
plosion ; and afterward, on removing the thumb, the weight
of the atmosphere forces the mercury into the shorter leg,
to supply the partial vacuum occasioned by the union of the
gases. Proper allowances being made for temperature and
pressure, the quantity of residual gas is read on the gradua-
tion, and a calculation can then be made of the amount of
oxygen present. If the gas contains carbon, carbonic acid
would be formed, and must be absorbed by potash solution.
407. Volta's eudiometer, represented in fig. 292,
is a very complete instrument for gas analyses
over the pneumatic-trough. In this instrument
the explosion is made in a thick glass tube A 8,
into which the electrical spark is passed by t. The
graduated measure p screws into the funnel D, and
is used to measure the portion of gas to be deto-
nated, which is poured in by the funnel 0 at
bottom. Before use, the tube P is removed, the
cocks R and S are both opened, and the whole in-
strument sunk in the cistern until it is entirely full
of water. The cock R is then shut, the portion
of gas measured in P and introduced by C, the cock
S closed, and explosion made. If any residue re-
mains, its quantity is measured by opening It,
when it rises into P, previously filled with water, .
and its quantity is read off on the graduation.
The metallic strap p serves as a communication
for the electric circuit, and also as a scale of equal
parts for ruder measurements of gas. This instru-
ment is well adapted for rapid class illustration,
in the lecture room, and is applicable in all eu-
diometrical experiments in which gaseous analysis
is to be performed by oxygen and hydrogen. For
accurate research, the beautiful eudiometer of
Regnault is the most reliable instrument.
408. The explosion of oxygen and hydrogen gases, when
mingled in atomic proportions, is very severe, and can be
performed safely only on very small volumes of the gases,
or in strong vessels of metal. The ingenuity of the demon-
strator will devise many instructive and amusing experi-
H'*w is the carbonic acid removed? 407. What is Volta's eudiometer?
How is it used ? 408. What illustrations are given of the severity of the
explosion of oxygen and hydrogen ?
16
Pig. 292.
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242 NON-M2TALLI0 ELEMENTS.
ments depending on the explosion of this mixture. The
r pistol, and hydrogen-gun, (fig. 293,) a blad-
filled and fixed from a pin-hole or by an
electric spark, soap-bubbles, and other familiar
• illustrations, all give evidence of the energy of
the action by which water is formed from die
union of its elements. The explosion is probably
due to the rush of air consequent on the sudden
expansion and immediate condensation of a vo-
Fig. 293. lume of steam formed at the most intense heat
which can be produced by art.
The union of oxygen and hydrogen can, however, be ef-
fected slowly and quietly, without any explosion or visible
combustion. This is accomplished by passing the mixed
gases through a tube heated below redness ; and at a still
lower temperature, if the tube contains coarsely powdered
glass or sand. We see in this case an instance of that re-
markable phenomenon called " surface action/' (251) be-
fore alluded to.
409. Professor Dobereiner, of Jena, observed, in 1824,
that platinum in the state of fine division, known as spongy
platinum, would cause an immediate union of these gases.
A drop of strong chlorid of platinum evaporated on writing
paper, and the paper burned, gives platinum in that state,
and such a pellet of paper may be prepared in an instant
and used to fire hydrogen. The common instrument
employed for lighting tapers is made by taking advantage
of this principle. A little spongy platinum is formed into
a ball, and mounted on a ring of wire (fig. 294)
which slips within the cup d on the top of gas-
holder a (fig. 295.) The gas is generated by the
action of dilute acid in the outer vessel a on a
lump of zinc z hanging in the inner vessel /, and
Fig. 294. jg jet ont at pieasure by the cock c, issuing in a
stream on the spongy platinum. The latter is at once
heated to redness by the stream of hydrogen, which is con-
densed within its pores to such a degree that it combines
with a portion of oxygen, always present in the sponge by
atmospheric absorption. The union of these gases is attended
by intense heat, and, as a consequence, the platinum at once
glows with redness, and the hydrogen is inflamed. After
How is this union effected slowly ? 409. What was the observation oi
Dobereiner? Describe the hydrogen lamp ?
Digitized
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COMPOUNDS OF HYDROGEN.
24a
tome time the sponge loses this property to
a certain extent, but it is again restore' ~
being well ignited. When the spongy
tinum is mixed with clay and sal-ammoniac
made into balls and baked, its effects are less
intense, and such balls are often used in analy-
sis to cause the gradual combination of gases.
Faraday has shown that clean slips of pla-
tinum foil, and even of gold and palla-
dium, can effect the silent union of hydro- <
gen ana oxygen. For this purpose the pla-
tinum is cleaned in hot sulphuric acid, washed
thoroughly with pure water, and hung in a jar ls*
of the mixed gases. Combination then takes place so ra-
pidly as to cause at every instant a sensible elevation of the
water in the jar. If the metal is very thin, it sometimes
becomes hot enough during the process of combination to
glow, and even to explode the gases.
410. The same effect of platinum in causing combination
is seen in other bodies besides oxygen and hydrogen. Seve-
ral mixtures of carbon gases will act with platinum in the
same way ; and the vapors of alcohol or ether
may be oxydized by a coil of platinum wire
hung from a card in a wineglass (fig. 296)
containing a few drops of either of these
fluids. The coil of wire is heated to red-
ness in a lamp, and, while still hot, is hung
in the glass ; it then, if air has free access,
retains its red-hot condition as long as any
vapor of ether or alcohol remains. In this
case, only the hydrogen of the ether, or al-
cohol, is oxydized, and the carbon is unaf-
fected ; a peculiar irritating acid vapor is given off, which
affects the nose and eyes unpleasantly. Little balls of pla-
tinum sponge suspended over the wick of an al- f\
cohol lamp will, in like manner, glow for hours I
after the lamp is extinguished. A spirit-lamp fed
with alcoholic ether will cause the coil of plati-
num wire (fig. 297) to glow for hours in the same
way, constituting what has been called the aphlb-
gistic lamp.
What has Faraday shown on this point ? 410. How does platinum
act on vapors ? What is the aphlogistio lamp ?
Fig. 296.
Fig. 297.
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244
NON-METALLIC ELEMENTS.
411. The oxyhydrogen blowpipe of Hare enables tbt
chemist to use safely the intense heat produced by the com-
bustion of oxygen and hydrogen. In Dr. Hare's instru-
ment the two gases were brought from separate gas-holders
and mingled only in the moment of contact. The flame of
the oxyhydrogen blowpipe differs from the flame of a lamp
or candle by being, so to speak, a cone of aerial matter en-
tirely ignited in every part, while the flame of a candle is
ignited only on the outside,
(460.) The structure of
the jet contrived by Profes-
sor Daniell illustrates this,
Fig. 298. where the oxygen tube o is
seen (figure 298) to pass
through that carrying the hydrogen, H. Thus the combus-
tible gas is in contact with the oxygen to burn it both from
the air and from the instrument. The let may be pro-
vided with a cock (fig. 299) and connected with the gas-
holders by two flexible pipes attached at 0 and H. The
o
Fig. 299.
Fig. 301.
Fig. 300.
gas-holders may conveniently be
made of impervious caoutchouc cloth,
arranged with pressure boards, and
weights as in fig. 300, an arrange-
ment which admits of convenient
transportation and dispenses with
the use of water. The gas is ad-
mitted and expelled by the flexible
pipes p and controlled by the cocks c.
The effects of the compound blow-
pipe may also be safely produced
by passing a stream of oxygen from
a gas-holder (fig. 301) through the
411. What is Hare's blowpipe ? How does its flame differ from common
flames ? How is the jet fig. 298 constructed ? How are the gases disposed ?
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COMPOUNDS OP HYDROGEN.
245
flame of a spirit-lamp w. The jet is regulated by the cock
I, while the lamp-flame supplies the hydrogen.
412. The mixed gases, in atomic proportions, are some-
times forced by a condensing syringe into a very strong
metallic box, from which they issue by their
own elasticity. To prevent the danger of
explosion, a contrivance is employed called <
" Hemming's safety tube." This is a brass (
tube, six or eight inches long, filled with fine
brass wire, closely packed, and having a coni- i
cal rod of brass forcibly driven into their
centre, by which the wires are very closely
crowded together. This forms in fact a great
number of small metallic tubes, through which
the gas must pass. It is a property of such
small tubes entirely to arrest the progress of
flame as we shall presently see. (Safety
lamp of Davy, 464.) The jet is screwed to <
one end of this tube, and the other end is
connected with the holder of the mixed gases. Fig. 302.
Several severe explosions, it is said, have occurred, even with
all these precautions ; so that if the mixed gases are used
at all, it should only be in a bag or bladder, the bursting
of which can be attended with no danger.
413. The effects of the compound blowpipe are very
remarkable. In the heat of its focus the most refractory
metals and earths are fused, or dissipated in vapor. Plati-
num, which does not melt in the most intense furnace of the
arts, here fuses with the rapidity of wax, and is even vola-
tilized. Even those metallic oxyds, as lime, magnesia, and
alumina, which are entirely infusible in any other artificial
heat, yield to this focus. By the adroit management of the
keys, which a little practice soon teaches, we can either re-
duce metallic oxyds, or oxydize substances still more highly.
The flame of the mixed gases falling on a cylinder of pre-
pared lime, adjusted to the focus of a parabolic mirror, pro-
duces the most intense artificial light known. This is what
is called the Drummond light. It is extensively employed in
distant night-signals, and can be seen farther at sea than any
412. How are the mixed gases burned safely? What is Hemming's
safety jet? 413. What are the effects of the compound blowpipe*
What it the Drummond light ?
Digitized
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246 NON-METALLIC ELEMENTS.
other light. It is also used as a substitute for the sun's light
in optical experiments. The galvanic focus alone, among
artificial sources of light, surpasses it, (200.)*
History of Water.
414. Water, when pure, is a colorless, inodorous, tasteless
fluid, which conducts heat and electricity very imperfectly,
refracts light powerfully, and is almost incapable of com-
pression. We have already made so much use of water, in
illustration of the laws of heat and of chemical combina-
tion, in the former part of this volume, that the student
must already be familiar with many of its attributes. Its
greatest density, it will be remembered, (103,) is found to
be at 39°*5, or, more exactly, 39°-83. It is the standard
of comparison (33), for all densities of solids and liquids.
In the form of ice, its density is 0-94, and at 32° it freezes.
One imperial gallon of water weighs 70,000 grains, or just
ten pounds. The American standard gallon holds, at
39°-83 Fahr., 58,372 American troy grains of pure distilled
water. One cubic inch, at 60° and 30 inches barometer,
weighs 252yy^ grains, which is 815 times as much as a like
bulk of atmospheric air. One hundred cubic inches of
aqueous vapor, at 212° and 30 inches barometer, weigh
14-96 grains, and its specific gravity is 0*622. Water
boils under ordinary circumstances at 212°; but we have
seen that its boiling point was very much afFected by the
nature of the vessel. It evaporates at all temperatures.
415. The conversion of water into ice is attended with
On toJttm *i$fou fc^0 exerc*se °f crystallo-
^K SlPii rail? &en*c attractions, although
1 |P* ^fir the resulting forms are
Fig- 303. rarely visible. But in
snow we often see beautifully grouped compound crystals,
resulting from the union of forms derived from the hexago-
nal prism. Figure 303 gives some of the more simple of
414. What are the properties of water ? What the temperature of itt
greatest density ? What the density of ice ? What that of a cubio
inch ? of a gallon ? of its vapor ? 415. What is said of the crystalliza-
tion of water?
* Mr. E. N. Kent, of New York, furnishes a very efficient and cheap form
of compound blowpipe, with gas-bags and Drummond light apparatus.
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COMPOUNDS OF HYDROGEN.
247
these forms. The laws of congelation of water have already
been fully explained, 123.
416. Pare water is never found on the surface of the
earth; for the purest natural waters, evaporated to dryness,
leave always a visible residue, containing small quantities of
earthy or saline matters which have been dissolved from the
rocks and soil. Moreover, all good water — that which is
fit for the use of man — has a considerable quantity of car-
bonic acid and atmospheric air dissolved in it, (332,) and
without which it would be flat and unpalatable.
A jar of spring water placed under a bell on the
air-pump (fig. 304) will appear to boil as the
exhaustion proceeds from escape of the dissolved
air. It is upon this air that the fish and other water-
breathing animals depend for life ; and conse-
quently, when a vessel containing fish is placed <
on the air-pump and the air exhausted, the fish are
seen soon to give signs of discomfort, (fig. 305,)
and will die if the operation is continued.
Many mineral springs, besides the saline
matters they hold in solution, are highly
charged with sulphuretted hydrogen, car-
bonic acid, and other gases derived from
chemical changes going on in the beds
from which they flow.
Pure water can be procured only by
distillation, and it is a substance of such
indispensable importance to the chemist,!
that every well-furnished laboratory is pro-
vided with means for its abundant prepa-
ration. A copper still, well tinned, and connected with a
pure block-tin worm or condenser, answers very well to pro-
duce the common supply. • But very accurate operations
require it to be again distilled in clean vessels of hard glass.
417. The solvent powers of water far exceed those of
any other known fluid. Nearly all saline bodies are, to a
greater or less extent, dissolved by water, and heat generally
aids this result. In the case of common salt, however,
and a few other bodies, cold water dissolves as much as hot.
What depends on the presence of air in the water ? What other
gases are found in it ? How is pure water obtained ? 416. What fo-
reign substances aro found in water ? How is the air in water shown ?
Why important to animal life ? 417. What are the solvent powers of water ?
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248
NON-METALLIC ELEMENTS.
The solvent powers of pure water are generally greater
than those of common water.
Gases are nearly all absorbed or dissolved in cold water,
and some of them to a very great extent, while others, as
hydrogen and common air, very slightly. Hot water dis-
solves many bodies which are quite insoluble in cold,
especially when aided by small portions of alkaline matter.
The waters of the hot springs in Iceland and Arkansas de-
posit much silicious matter before held in solution ; and Dr.
Turner found that common glass was dissolved in the cham-
ber of a steam-boiler at 300°, and stalactites of silica were
formed from the wire basket in which the glass was sus-
pended.
418. Water always absorbs the same volume of a given
gas, whatever may be its density : thus, of carbonic acid,
of ordinary tension, it dissolves its own volume ; it would do
no more if the gas were reduced to half its first density ; and
it dissolves the same volume when the pressure is at 30
atmospheres. Hence water which has absorbed gases under
pressure, parts with them in effervescence when that pressure
is removed. Again, if a mixture of gases is present at a
given tension, water absorbs of each the same volume as it
would take up if only that one was present. Such, it will
be remembered, is the fact with regard to the gases of the
atmosphere, (332.) Gases dissolved in water are all ex-
pelled by boiling. If,
therefore, we would
know what- volume
of a given gas was
dissolved in water,
the fact is accurately
determined by boiling
a measured quantity
in a flask quite full,
as in figure 806, and
conveying the escap-
ing gas by a bent tube
(also previously filled
with water) to a gra-
duated jar on the
Fig. 306.
What of the action of hot water ? 418. What volume of gases does
water absorb ? How does pressure affect this ? How of mixed gases ? How
is the volume of gases contained in water determined? Describe fig. 306.
Digitized
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COMPOUNDS OF HYDROGEN. 249
mercurial cistern. We then measure the volume of gas ex*
pelled directly.
419. The powers of water as a chemical agent are very
various and important. From its neutral, mild, and salu-
tary character, we are accustomed to regard it only as a
negative substance, possessed of little energy, while it is in
fact one of the most important chemical agents in our pos-
session. Besides its solvent powers, we know that it com-
bines with many substances, forming a large class of hy-
drates: hydrate of lime and potash are examples. It is
also, as we have seen, (320,) essential to the acid properties
of common sulphuric, phosphoric, and nitric acids, acting
here the part of a much more energetic base than in the hy-
drates. It forms an essential part in the composition of
many neutral salts, and can be replaced in composition by
other neutral saline bodies ; while as water of crystallization
it discharges still another important and distinct function,
the crystalline forms of many salts being quite dependent
on its presence in atomic proportions. Of organic struc-
tures, both animal and vegetable, it forms by far the most
considerable constituent. Its vapor at high temperatures
displaces some of the most powerful acids, as Tilghmann has
shown, in his patent process for procuring the alkaline bases
by decomposing their sulphates, chlorids, and even, to some
extent, silicates, by vapor of water at a high temperature.
Sulphate of lime, for example, so treated, has all its sul-
phuric acid driven off as S03, and caustic lime is left behind.
The geological importance of these facts can hardly be over-
estimated.
420. Peroxyd or Binoxyd of Hydrogen. — This curious
compound was discovered in 1818, by M. Thenard. It is
obtained in decomposing the peroxyd of barium by as much
very cold solution of hydrofluoric acid (fluosilicic or phos-
phoric acid may be used as well) as will exactly saturate
the base, the whole being precipitated as fluorid of barium.
The reaction may be expressed thus :
Peroxyd of barium. Fluohydric add. Fluorid of barium. Peroxyd of hydrogen.
BaOa + HF = BaF + HOa.
The peroxyd of hydrogen remains dissolved in the water,
which is freed «from the insoluble fluorid of barium by filtra-
419. What are the chemical powers of water ? What is crystallization-
water? What are Tilghmann's experiments? 420. What is the per-
oxyd of hydrogen ? How procured ? Give the reaction.
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E
1S50 NON-METALLIC ELEMENTS.
lion, and then evaporated in the vacuum of an air-pump by
the aid of the absorbing power of sulphuric aeid.
421. Properties. — The properties of this body are very
remarkable. When as free from water as possible, it is a
syrupy liquid, colorless, almost inodorous, transparent, and
possessed of a very nauseous, astringent, and disgusting taste.
ts specific gravity is 1*453, and no degree of cold has ever
reduced it to the solid form. Heat decomposes it with effer-
vescence and the escape of oxygen gas. It can be preserved
only at a temperature below 50°. The contact of carbon and
many metallic oxyds decomposes it, often explosively, and
with evolution of light. No change is suffered by many
bodies which decompose it; but several oxyds, as those of
iron, tin, manganese, and others, pass to a higher state of
oxydation. Oxyd of silver, and generally those oxyds
which lose their oxygen at a high temperature, are reduced
to a metallic state by this decomposition. When diluted,
and especially when acidulated, the peroxyd of hydrogen is
more stable. It is dissolved by water in all proportions,
bleaches litmus paper, and whitens the skin. None of its
compounds are known, nor does it seem to have any ten-
dency to combine with other bodies.
Compounds of Hydrogen with the II. and III. Classes.
422. The eminently electropositive character of hydrogen
causes it to form well-characterized and analogous com-
pounds with all the members of the oxygen group. These
binary compounds have frequently been called the hydracids}
in distinction from those acid bodies already considered,
which, in parity of language, have been called the oocacids.
It is, however, more in accordance with facts and the
principles of a philosophic classification, to look upon these
bodies as having in reality the same essential characters as
the chlorids, bromids, iodids, &c, of other electro-positive
bases. The principles of our nomenclature require these
compounds to be called after their electro-negative elements,
t. e, chlorohydric acid, bromohydric acid. Their general
formula is HE. The compounds of hydrogen to be con-
sidered under this head are —
421. "What are its properties ? 422. What are the hydracids ? What
view is taken of their constitution ? What compounds are enumerated
under this head ? What is their general formula ?
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0OMPOUND8 OP HYDROGEN. 251
Solphydric aoid HS
Selenhydrio acid. HSe
Tellurhydrio acid HTe
CMorobydric acid. HOI
. Bromohydrio acid. HBr
lodohydric acid HI
' Fluohydric acid. HF
423. Hydrogen and chlorine, mingled in the gaseous
state, combine with explosion by the touch of a match,
forming chlorohydric acid. The rays of the sun effect the
same result instantaneously, while in diffuse light combina-
tion follows in a gradual manner and quietly. In the dark,
no union occurs, showing that light in this case plays the
part of heat, and impresses, as we shall see, a peculiar con-
dition on chlorine. If two vessels of equal
Capacity (fig. 307) are filled, the one, A, with
dry hydrogen, the other, B, with dry chlo-
rine, by displacement, and are then united,
as seen in the figure, on exposing them with
precaution to the sun's direct rays, an im-
mediate explosion follows. Dr. Draper has
shown that chlorine gas which had been ex-
posed alone and dry to the sun's light ac-
quired the power of forming this explosive _,. 307
union with hydrogen, even in the dark, and lg*
retained it for some time; while, on the other hand, chlorine
prepared in the dark manifests no avidity for hydrogen un-
less exposed to the light. This fact was before mentioned
(288) when speaking of the active and passive conditions
of chlorine. In its passive state, (as prepared in the dark,)
it actually replaces hydrogen in the constitution of many
organic bodies, or, in other words, assumes an electro-posi-
tive condition. The effect of the sun's light is to confer a
new state upon it, probably by a new arrangement of its
molecules, by which its character is completely changed.
It then apparently becomes highly electro-negative.
The decomposition of water by chlorine (288) evinces its
strong affinity for hydrogen. Chlorine thus becomes one
of the most powerful oxydizing agents known, since the
nascent oxygen given off during the decomposition of water
attacks with energy any third body which may be present
that is capable of combining with it.
424, Chhrohydric Acid, HC1. — If the experiment (fig.
423. How do chlorine and hydrogen act when mingled? Describt
fig. 307. What has Draper shown ? What is the passive state of chlo-
rine ? What relation has it in this state to organic bodies ? On what
does the decomposition of water by chlorine depend ?
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252 NON-METALLIC ELEMENTS.
807) is placed in diffuse light, the green color of the gas is
seen gradually to diminish and finally to disappear alto-
gether; and, on opening the junction beneath mercury, no ab-
sorption occurs, and the vessels are found to be filled with
chlorohydric acid gas. It appears therefore that this acid if
formed by the union of equal volumes of the constituent gases
without condensation. Its density is consequently equal to
half the sum of the united densities of chlorine and hydro-
gen, i. e. 2-44 -f -069 = 2-509 -s-2 = 1-254, theoretical den-
sity of chlorohydric acid gas. Experiment gives 1-2474.
425. Chlorohydric acid is a colorless, acid, irrespirable
gas. It forms copious clouds of acid vapor with the moist-
ure of the air, very suffocating, and irritating the eyes. It
extinguishes a lighted candle, and is not decomposed by
electricity. It is very soluble in water, which at 32° takes
up about 500 times its volume and acquires a density of
1-21. At a higher temperature it absorbs less. This gas is
therefore collected over mercury. A bit of ice passed up
to a jar of it on the mercury cistern, is fused immediately
by its avidity for water, a dilute solution of chlorohydric
acid results, and the mercury rises to fill the jar. With a
pressure of over 26 atmospheres it becomes a colorless liquid,
which has never been frozen.
426. Preparation. — For experimental purposes in the
laboratory it is sufficient to warm the strong commercial
liquid acid, which parts with a large portion of gas at a gentle
heat. This may be dried
by passing it through a
chlorid of calcium tube.
The apparatus thus ai-
ranged is shown in figure
308. The concentrated
acid is placed in c and its
moisture is removed by
,-the chlorid of calcium
apparatus a. The weight
Fig. 308. of tne gas enaDies U8 to
collect it by displacement of air in dry vessels b. For
this purpose it is not usually requisite to dry it.
In the arts it is always obtained from the decomposition
424. What is the constitution of chlorohydric acid? What is its theo-
retical composition and density ? Its experimental ? 425. What are its
properties ? How soluble in water ? How collected ? 420. How is it
prepared for experiment in the laboratory ? Describe fig. 308.
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COMPOUNDS OF HYDROGEN,
25ft
of common salt, (chlorid of sodium, NaCl,) by sulphurie
acid. The reaction is sufficiently simple : NaCl -f SOt.
HO = (NaO.S08) + HC1. The apparatus employed in
this process is shown in
fig. 309. Common salt
is placed in the flask a,
provided with a safety
tube / and an eduction
tube h. The sulphuric
acid fox decomposing the
salt is introduced at
pleasure through/. The
action is aided by a gen-
tle heat from the fur-
nace below. Thechloro-
hydric acid is rapidly
evolved and passes into
c, where it is washed by
a little warm water and
thence by e to the last
bottle d, where it is ab-
sorbed by the ice-cold
water which it contains.
In the middle bottle is
a tube gf of large size
and open at both ends, FiS« 3a9*
its lower extremity dips into the wash-water. This
contrivance prevents the accident which is otherwise
likely to happen should a partial vacuum occur in a,
from a cessation of the action ; when the pressure
of the air on the fluid in d would carry it back into
c, and finally into a. The safety tube (fig. 310) at-
tached to the flask a also serves to prevent this acci-
dent as well as to introduce the* acid. When a liquid
is poured in at the funnel-top, it must rise as
high as the turn, before it can pass down into the
flask, and a portion of the fluid is therefore always
left behind in the bend, which serves as a valve
against the entrance of air, and also effectually pre-
vents an explosion of the flask in case the tube of
delivery should become stopped. This simple con- lg*
How is it procured in the arts ? Give the reaction. Describe the appa-
totus, fig. 309. What is a safety tube ? Describe fig. 310.
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254
NON-METALLIC ELEMENTS.
trivance we have often employed but have not before ex*
plained its action. This same apparatus may be employed in
making solutions of all the absorbable gases, and is so simple
as to be within the means of the humblest laboratory ; the
essential parts being only wide-mouthed bottles, glass tubes,
a gas bottle or flask, and corks.
427. Pure chlorohydric acid is procured by distilling the
commercial acid. The distilling apparatus employed for
this purpose is seen in fig. 311. The heat is applied by a
sand-bath beneath the retort. The gas given off is absorbed
by a little water placed in the last bottle, which is connected
by a bent tube with the two-necked receiver. If the corn-
Fig. 311.
mercial acid is diluted by water until it has the specific gra-
vity I'll, it no longer evolves acid fumes when heated, and
the fluid distilled has the same density as that in the retort,
retaining 16 equivalents of water.
428. Properties. — Liquid chlorohydric acid is a colorless,
highly acid, fuming liquid, having when saturated a specific
gravity of 1-247 : it then contains 42 parts in a hundred of
real acid. Its purity is tested by its leaving no residue on
evaporating a drop or two on clean platinum, and by its
giving no milkiness when a solution of chlorid of barium is
added to it, (due to sulphuric acid.) Neutralized by
ammonia, it ought not to become black when hydrosut
427. How obtained pure? Describe fig. 311. At what density does it
distill unchanged? 428. What are the properties of the liquid acid?
What ar* tests of its purity ?
Digitized
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COMPOUNDS OF HYDROGEN. 265
phuret of ammonium is added, (due to iron.) This acid is
an electrolyte, and is also decomposed by ordinary elec-
tricity. A mixture of muriatic acid gas with oxygen, passed
through a red-hot tube, produces water and chlorine. The
commercial acid is always impure, and colored yellow by
free chlorine, iron, and organic matters.
Tate. — A solution of nitrate of silver detects the pre-
sence of a soluble chlorid, or of chlorohydric a/jid,
by forming with it a whito curdy precipitate of
chlorid of silver, which is soluble in ammonia,
but insoluble in acids or water. A rod a, if dip-
ped in ammonia and held over a glass containing
chlorohydric acid, gives off a dense white cloud
of chlorid of ammonium. Fi«- 312-
429. The uses of chlorohydio acid are very numerous.
Its decomposition by oxyd of manganese affords the easiest
mode of procuring chlorine, (282.) It dissolves a great
number of metals and oxyds, forming chlorids, from which
these metals may be obtained in their lowest state of
oxydation. In chemical analysis and the daily operations
. of the laboratory it is of indispensable use.
Chlorohydric acid is made in the arts in immense quanti-
ties, especially in England, where the carbonate of soda is
largely made from common salt (chlorid of sodium) by
the action of sulphuric acid. Mingled with half its own
volume of strong nitric acid, it makes the deeply colored,
fuming, and corrosive aqua-regia. This mixed acid evolves
much free chlorine, which in its nascent state has power to
dissolve gold, platinum, &c, forming chlorids of those
metals, and not nitromuriates as was formerly supposed.
As soon as all the chlorine is evolved, this peculiar power
of the aqua-regia is lost.
430. Bromohydric Acid, HBr, Bromid of Hydrogen. —
Hydrogen and bromine do not act upon each other in the gase-
ous state, even by the aid of the sun's light; but a red heat
or the electric spark causes union — only among those parti-
cles, however, which are in immediate contact with the heat,
the action not being general. Bromohydric acid may be
prepared by the reaction of moist phosphorus on bromine in
a glass tube (fig. 313.) The gas given off must be collected
What tests are named ? 429. What are its uses ? What is aqua-regia t
430. What is bromohydric acid ? How prepared ?
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256 NON-METALLIC ELEMENTS.
over mercury. It is composed, like chlorohydric acid, of
equal volumes of its elements not condensed. Its specific
gravity is 2*731, and it is condensed by cold and pressure
into a liquid. In its sensible properties it bears a close re-
semblance to chlorohydric acid. With the nitrates of silver,
lead, and mercury, it gives white precipitates similar to the
chlorids. It has a strong avidity for water, and dissolves
largely in it, giving out much heat during the absorption.
The saturated aqueous solution has the same reactions as the
dry acid, and fumes with a white cloud in contact with air.
It dissolves a large quantity of free bromine, acquiring
thereby a red tint.
431. Iodohydric Acid. — This body may be formed by
the direct union of its elements at a red-heat, but is
more easily prepared by acting on iodine and water with
phosphorus, by which means the gas is formed in large
quantities. The action of phosphorus and iodine is violent
and dangerous, but may be regulated and made safe by
putting a little powdered class between each layer of phos-
phorus and iodine, (fig. 313.) Phos-
phoric acid is formed and remains in,
solution, while the iodohydric acid
gas is given out, and may be col-
lected over mercury, or dissolved
in water. The dry gas has a great
avidity for water. Its specific
gravity is 4*443, being formed, like
> the last two compounds, of one vo-
Fig. 313. lume of each element uneondensed.
Cold and pressure reduce it to a
clear liquid, which, at— 60° Fahr.,freezes into a colorless solid,
having fissures running through it like ice. It forms a very
acid fluid by solution in water, which has, when saturated, a
specific gravity of 17, and emits white fumes. The aqueous
solution is also prepared by transmitting a current of hydro-
sulphuric acid through water in which free iodine is sus-
pended. The gas is decomposed, sulphur set free, and
hydriodic 2*cid produced, which is purified from free hydro-
sulphuric acid by boiling, and from sulphur by filtration.
432. Properties. — The aqueous iodohydric acid is easily
431. How is iodohydric acid prepared ? What are its properties ? How
L» it« aqueous solution prepared ?
Digitized by VjOOQ IC
COMPOUNDS OP HYDROGEN. 257
decomposed by exposure to the air, iodine being set free.
It forms characteristic, highly colored precipitates with
most of the metals, particularly with lead, silver, and
mercury. Bromine decomposes it, and chlorine decomposes
both hydrobromic and hydriodic acids, thus showing the
relative affinities of these bodies for hydrogen. This acid
is a valuable reagent; its presence in solution is easily
detected by a cold solution of starch, which, with a few
drops of strong nitric or sulphuric acid, instantly gives the
fine characteristic blue of the iodid of starch.
483. Fluohydric acid is obtained from the decomposition
of fluor-spar by strong sulphuric acid. The operation must
be performed in a* retort of pure lead, silver, or platinum,
and requires a gentle heat. Fig. 314 shows
Hhe form of retort used for this purpose, the
junction of the head and body is made tight
by a lute of gypsum and water, fflrr^
ISj^ as any lute containing silica ™%ft
\^m will be attacked by the fluohy-
^^ dric acid. The sulphate of
Fig. 314. i*me reguitmg from the action
forms a solid insoluble mass in the body of
the retort : hence the necessity of so large an
opening. The fluohydric acid resulting is
condensed in a large tube of lead, bent as in Fig. 315.
fig. 315, so as to enter a refrigerant apparatus : at one end it
is luted to the beak of the retort, at the other is narrowed
to a small aperture. The reaction is expressed as follows :
Bi? SuLacid. ^ul. lime. *ȣ*
CaF + S08.H0 = S08.CaO + HF
The fluor-spar employed should be quite free from silica
and sulphur.
434. Properties. — Concentrated fluohydric acid is a gas
which at 32° is condensed into a colorless fluid, with a den-
sity of 1-069. Its avidity for water is extreme, and when
brought in contact with it, the acid hisses like red-hot iron.
Its aqueous solution, as well as the vapor of the acid, attack
glass and all compounds containing silica very powerfully. It
432. What are its characters? 433. How is fluohydric acid pre*
pared ? Describe the apparatus, fig. 314. What is the reaction ? 434.
What are its properties ?
IT
Digitized
byGoogk
258
NON-METALLIC ELEMENTS.
(s often used in the laboratory for marking test-bottled or gra-
duated measures, or biting in designs traced in wax on the
surface of v glass plates. It is a powerful acid, with a very
sour taste, neutralizes alkalies, and permanently reddens blue
litmus. On some of the metals its action is very powerful;
it unites explosively with potassium, evolving heat and light.
It attacks and dissolves, with the evolution of hydrogen, cer-
tain bodies which no other acid can affect, such as silicon, zir-
conium, and columbium. Silicic, titanic, oolumbic, and mo-
lybdic acids are also dissolved by it.
Fluohydric acid, in its most concentrated form, is a most
dangerous substance. It attacks all forms of animal matter
with wonderful energy. The smallest drop of the concen-
trated acid produces ulceration and death, when applied to
the tongue of a dog. Its vapor floating in the air is very
corrosive, and should be carefully avoided. If it falls, even
in small spray, on the skin, it produces an ulcer, which it is
very difficult to cure. For this reason it is quite inexpe-
dient for unexperienced persons to attempt its preparation.
By using a weaker sulphuric acid, however, or by having
water in the condenser, no risk is incurred. As before re-
marked, it attacks silica more powerfully than any other
body. This fact puts us in possession of an admirable mode
of analyzing silicious minerals, when we do not wish to fuse
them with an alkali.
435. Sulphydric Acid ', Sulphuretted Hydrogen. — When
the protosulphuret
of iron or the sul-
phuret of antimony
is treated with a dilute
acid, effervescence
occurs, and a gas is
given out having a
most disgusting, fetid
odor, which at once
reminds us of the
nauseous smell of bad
eggs. This process is
performed in the evo-
lution-bottle A, (fig.
What its uses? What of its safety ? How does it act on the organs?
What is its great affinity ? 435. What is hydro-sulphuric acid ? What if
its common name ?
Fig. 316.
Digitized
byGoogk
COMPOUNDS OP HYDROGEN.
259
816) in which a portion of sulphuret of iron is acted on by
dilate sulphuric acid turned in at the funnel-tube 6. The es-
caping gas is led by a to the inverted bottle. This operation
should be performed in a well-drawing flue or in the open
air. The reaction is FeS+S08+HO=FeO.S08-f HS.
If sulphuret of antimony is used, heat is needed; and we
must employ the apparatus fig. 317, and chlorohydric in-
0
Fig. 317. #
stead of sulphuric acid. This mode evolves no free hydro-
gen, which is present in small quantities when protosul-
phuret of iron is used. This is sulphuretted hydrogen gas,
one of the most useful reagents to the chemist, especially in
relation to the metallic bodies.
436. Properties. — Sulphydric acid is a colorless gas, of a
disgusting odor, like that of putrid eggs. Its density is
1-191, or a little heavier than air. It is liquefied at 50°
by a pressure of 15 or 16 atmospheres, and at — 122°
Fahrenheit it freezes into a white confused crystalline solid,
not transparent, and which is much heavier than the fluid,
sinking in it readily. Heat partially decomposes it. It
burns with a blue flame, depositing sulphur on the interior
of the bottle. Sulphurous acid and water are its products
of combustion. Mingled with 1£ volumes of oxygen the
combustion is complete, no sulphur is deposited, and there
How prepared ? Qive the reaction. Why is sulphuret of antimony
sometimes preferred ? 436. What are its properties ? Is it combustible 7
How is it decomposed ? How much oxygen burns it ? What are the pro-
dustf of combustion ?
Digitized
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260 NON-METALLIC ELEMENTS.
is a shrill explosion. Strong nitric acid also inflamos and
burns it. Chlorine, bromine, and jodine also decompose it.
Mingled with a considerable volume of air in contact with
organic matter, it slowly forms sulphuric acid. It is a true
but feeble acid.
Water, if cold, and recently boiled, dissolves 2} or 3 timet
its volume of sulphydric acid. Woulf 's apparatus (fig. 321)
is best adapted for this purpose. The solution has the
characteristic smell and taste of the gas and all its pro-
perties. If boiled it loses all its gas, and if kept a short
time it becomes troubled from precipitation of sulphur : this
is due to oxygen dissolved in the water. The solution of
sulphydric acid should therefore be kept in well-stopped bot-
tles, quite full. This solution is much used in the labora-
tory. Added to solutions of metallic salts
it throws down characteristic precipitates,
offering to the chemist an easy mode of
distinguishing substances or of separating
them from one another. The gas passed
directly into solutions of metals as in fig.
318, answers the same purpose. Such an
Fig. 318. apparatus is conveniently kept for use,
and should be always at hand.
437. It occurs in nature in many mineral springs, giv-
ing the water highly valuable medicinal characters. Many
such springs in this country are much resorted to, as at Sha-
ron and Avon, N. Y., and the sulphur springs of Virginia.
At Lake Solfatara, near Home, this gas is given off copi-
ously with carbonic acid. The disgust at first felt at drink-
ing these nauseous waters is soon overcome, and those patients
who take them in large quantity soon observe the gas to
penetrate their whole system and exude in their perspiration.
Silver coin, and other silver articles in the pockets of such
persons, are soon completely blackened by the coating of
sulphuret of silver formed on their surface.
Although salutary when taken into the stomach, it is,
even when present in the air in only a small quantity, a
deadly poison to the more delicate animals. Numerous
deaths are also recorded of those who have attempted to work
in vaults and sewers where it abounds.
How soluble is it? Will the solution remain unchanged? Why not?
487. What is its natural history ? How does it affect life ?
Digitized
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COMPOUNDS OF HYDROGEN.
261
438. When sulphurous
acid and sulphuretted hy-
drogen gas are brought
together in a common
receiving vessel, mutual
decomposition ensues,
and the sulphur of both
is thrown down, which
attaches itself to the sides
of the vessel in a thick
yellow pellicle. The sul-
phurous acid is evolved
in a, (fig. 319,) (310,) Fl* 319'
and sulphydric acic in b, and both are carried to the bottom
of the middle bottle at a 6.
Sulphydric acid is formed from 1 volume of hydrogen = 0-0692
And * volume of sulphuric vapor~£ = i'1090
Giving for the theoretical density of the gas 1*1782
While experiment gives 1*1912
There is a bisulphydrio acid, HSa, but no further men-
tion will be made of it.
439. Selenhydrio and tellurhydric acids are exactly analo-
gous to the last-named compound, and their general interest
is so small that we pass them without further notice.
Compounds of Hydrogen with Class III.
440. The compounds which hydrogen forms with the nitro-
gen group are strongly contrasted in chemical and physical
characters with the remarkable natural family which has
just engaged our attention. The latter are all acid, and gene-
rally in an eminent degree. The compounds of hydrogen
with the nitrogen group are, on the contrary, either neutral
or strongly basic, forming a series of salts or peculiar com-
pounds with the hydracids before named.
The compounds named under this head are —
Ammonia NH,
Phosphuretted hydrogen PHS
We might add in the same connection the hydrogen com-
pounds of arsenic and antimony, AsH8 and SbH3, sub-
438. What is the experiment in fig. 319 ? What is the composition of
this gas? What its theoretical and experimental :&nsity? 439. What
compounds are used in this section ? Give the formulae. What other
similar compounds are named ?
Digitized
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262 NON-METALLIC ELEMENTS.
stances quite similar to PH3 in many of their attributes,
but convenience refers these to the metallic bodies.
441. Origin of Ammonia, — Hydrogen and nitrogen do
not unite in mixture, nor by the aid of heat. A series of
electrical sparks, as in the case of nitrogen and oxygen,
(333,) passed through a mixture of hydrogen and nitrogen,
will produce a limited quantity of ammonia. But it is only
when these gases come together at the moment of their
evolution from previous combination, (nascent state, 269,)
and while, so to speak, they still have the impression of change
upon them, that they unite with freedom. Ammonia is there-
fore a constant product in the decomposition of those organic
substances which contain nitrogen. It is in fact from the
destructive distillation of horns, hoofs, and other highly ni-
trogenized forms of animal matter, that the ammonia of
commerce is in great measure derived.
This nascent union also occurs without the aid of the
products of life. A fragment of metallic iron in moist air
soon contracts a film of oxyd of iron, which, like other porous
bodies, absorbs the atmospheric gases, while the electrical
influence of the oxyd of iron with water and metallic iron,
forming in fact a voltaic circuit, effects a slow decomposition
of water, whose hydrogen unites in its nascent state with
atmospheric nitrogen to form ammonia. Thus we reach an
explanation of the well-known fact, that oxyd of iron often
contains a notable proportion of ammonia.
442. Again : Hydrogen is evolved, as all know, by the
action of dilute sulphuric acid on zinc. Nitric acid effects
the same end, if of a certain concentration. But if nitric
acid be added drop by drop to dilute sulphuric acid, while
hydrogen is being evolved by its action on zinc, the effer-
vescence from escaping hydrogen is checked, and, if the ad-
dition of nitric acid is cautiously made, a point is reached
when the evolution of hydrogen ceases entirely. The zinc
is still dissolving, but the hydrogen is immediately seized
as fast as it is evolved, by the nitrogen from the decomposed
nitric acid, ammonia is formed, and the fluid is found to Con-
tain a notable quantity of nitrate and sulphate of ammonia.
441. What is the origin of ammonia ? How do the two gases unite ?
flow does this happen from the dung of animal matters ? How without
their aid? 442. How is ammonia formed by the solution of sine?
Describe the process.
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COMPOUNDS OF HYDROGEN.
263
443. Ammonia was known to the ancients, and bears proof
of its antiquity in its very name. They obtained sal-ammo-
niac by burning the dried dung of camels in the desert, whence
the name, ammonia, from ammos9 sand, in allusion to the
desert, which was also called Ammon, one of the names of
Jupiter. The sal-ammoniac, sulphate of ammonia, and am-
monia-alum, are found among the products of voicanos.
Free ammonia is exhaled from the foliage and found in the
juices of certain plants, in the perspiration of animals, in
iron rust, and absorbent earths. Rain water also contains a
small quantity of ammoniacal salts, washed out of the atmo-
sphere; and the guano so much valued as a manure, is rich
in various ammoniacal compounds.
444. Preparation, — Ammonia is prepared by decompos-
ing sal-ammoniac, by dry lime and heat. For this purpose
equal parts of dry powdered sal-ammoniac and freshly slaked
dry lime are well mingled and heated in a glass, or, if the
Suantity is considerable, in an iron vessel. The lime takes
tie chlorohydric acid, forming chlorid of calcium, and am-
monia is given out as a gas. Fig. 320 shows the arrange-
ment for the purpose.
The ammonia is col-
lected over mercury.
In the laboratory it is
more convenient to
employ in the flask e
strong solution of am-
monia, which yields
a large volume of gas
at a gentle heat. If
it is required to dry
the gas, it cannot be
done by chlorid of
calcium, which ab-
sorbs it largely in the
cold, but dry caustic lime or potassa must be used.
445. Properties. — The dry gas is colorless, having the
very pungent smell so well known as that of "hartshorn"
(because it was procured formerly from the horns of the hart.)
Fig. 320.
443. What of the antiquity of ammonia? What natural sources are
named for it? 444. How is it prepared? Describe the process, ilg. 320.
445. What are its properties?
Digitized
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264
NON-METALLIC ELEMENTS.
It is, when undiluted, quite irrespirable, and attacks tha
eyes, month, and nose powerfully. It is strongly alkaline,
and is often called the volatile alkali. It restores the blue
of reddened litmus, turns green the blue of cabbage and
dahlia, and neutralizes the most powerful acids. Its density
is about half that of air, or 0*597. It does not support
combustion, but the flame of a candle as it expires in. the
gas is slightly enlarged, and surrounded with a yellowish
fringe. A small jet of ammoniacal gas may also be burned
in an atmosphere of oxygen. With its own volume of oxygen
it explodes by the electric spark, and produces water and
free nitrogen. Passed through a tube filled with iron wire,
and heated to redness, dry ammonia is entirely decomposed;
yielding for every 200 measures of ammonia, 300 measures
of hydrogen, and 100 of nitrogen. The metal in the tube
acts to decompose the ammonia solely by its presence^ (271.)
At a temperature of 50° it is liquefied with a pressure of
6i atmospheres, and with the ordinary pressure it is liquid
at — 40°, producing a white, translucent, crystalline solid,
heavier than the liquid.
446. Ammonia is instantly absorbed by water. A frag-
ment of ice slipped under the lip of an air-jar filled with dry
ammonia over the mercury cistern is melted at once, and
the mercury rapidly rises to supply the place of the absorbed
gas. This forms a weak solution of ammonia, as may be
shown by its action with reddened litmus. Cold water
dissolves 500 times its volume of ammonia, all of which is
Fig. 321.
How does it act with other bodies? How is it classed? What its
density? How as respects combustion ? How is it decomposed? What
Is the product ? 446. How absorbable is it?
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COMPOUNDS OF HYDROGEN.
265
expelled by heat. . This solution is called aqua ammonia.
It is prepared in a Woulf ' s apparatus b, c, d, (fig. 321,) and
is evolved from dry lime and sal-ammoniac in a. The tubes
i dip to the bottom of the water in each bottle, and slight
pressure may be made by causing the last % to dip into mer-
cury. The fluid is seen to mouut in o, o, o, indicating tho
pressure, which of course is greatest in 6.
447. Solution of ammonia, if saturated in the cold, is
lighter than water, being sp. gr. 0*870, containing 32}
parts in 100 of real ammonia. Its odor is overpowering,
causing suffusion of the eyes and a strong alkaline taste.
It boils at 130°, and freezes only at — 40°. It saturates
acids, and forms definite salts. Ammonia is always recog-
nized by its odor and its restoring the blue of reddened
litmus, carrying other vegetable blues to green, and browning
yellow turmeric. Its salts are decomposed by dry lime or
caustic potassa, evolving the characteristic ammoniacal odor.
A rod moistened in chlorohydric acid brought
near a vessel evolving ammonia causes an imme-
diate cloud of chlorid of ammonium, (fig. 322.)
It must be preserved in well-stopped bottles in
a cool place, as the heat of summer or of a warm
room causes gas enough to be evolved to blow
out the stopper of the bottle. Fi8- 322»
448. Hydrogen and Phosphorus. — Phosphurettcd Hydro-
gen.— This gaseous body is conveniently prepared by em-
ploying quicklime recently slacked, water, and a few sticks
of phosphorus, in a small retort, (fig. 323,) the ball of which
Fig. 323.
is nearly filled with the mixture. A gentle heat generates
How is aqua ammonia formed ? Describe Woulf 's apparatus. 447.
What are the properties of the solution ? How are its salts decomposed ?
448. How is pbosphuretted hydrogen obtained ?
Digitized
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266 HON-METALMG ELEMENTS.
the gas, which breaks from the surface of
the water (beneath which the beak of the
retort dips very slightly) in bubbles, that
inflame spontaneously as they reach the air,
rising in beautiful wreaths of smoke, which
float in concentric, expanding rings. Phos-
phuret of calcium thrown into a glass of
water (fig. 324) is instantly decomposed, and
evolves the spontaneously inflammable gas.
Fig. 324. Chlorohydric acid evolves from this com-
pound the variety of this gas which is not spontaneously
inflammable.
449. Properties. — This gas has a digusting, heavy odor,
like putrid fish, which is far more annoying than that of
sulphuretted hydrogen. It is transparent and colorless, has a
bitter taste, and, if dry, may be kept unchanged either in. the
light or dark. It loses its spontaneous inflammability by
standing a time over water, a body being deposited which
is probably phosphorus, in its red modification. It is
deadly when breathed. It acts very violently with oxygen
gas. If bubbles of it are allowed to enter ajar of oxygen,
each bubble burns with a most brilliant light and a sharp
explosion. The mixture of even a very small quantity with
oxygen would be quite hazardous, destroying the vessels.
Its proporty of spontaneous inflammability is undoubtedly
owing to a portion of free vapor of phosphorus. In its
chemical relations phosphuretted hydrogen is nearly neutral,
but is in some respects a base, as it forms crystalline salts
with bromohydric and iodehydric acids, which are decom-
posed again by water.
There are three phosphurets of hydrogen, PflH, PHfl, and
PH3. The second of these is a liquid, the third is the sub-
stance described above.
Compounds of Hydrogen with the Carbon Group.
450. Carbon and Hydrogen form a vast number of
compounds in the organic kingdom, many of which will
come under our consideration in the organic chemistry.
449. What are its properties? What is its most remarkable pro-
perty ? What its constitution ? 450. What compounds of hydrogen and
earbon are named ?
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COMPOUNDS OF HYDROGEN.
267
There are two gases, marsh gas and olefiant gas, or the
light and heavy carburetted hydrogens, which are found in
the inorganic kingdom, although they are derived from the
destruction of organic bodies. These two compounds we
will now consider. They are —
Light carburetted hydrogen gas CH,
Olefiant, or heavy carburetted hydrogen gas... C.H,
C«H«
451. Light Carburetted Hydrogen Gas; Marsh Gas;
Fire Damp. — This gas occurs abundantly in nature, being
formed nearly pure by the decomposition of vegetable mat-
ter under water, (marsh gas.) The bubbles which rise when
the leaves and mud of a stagnant pool or lake are stirred,
are light carburetted hydrogen, with some nitrogen and car-
bonic acid. It may be collected in such situations by means
of an inverted funnel and bottle, as
in figure 325. In coal mines it is
copiously evolved in company with
heavy carburetted hydrogen and
carbonic acid, (fire damp.) In the £
salt region of Kanawha, it flows =:
so abundantly from the artesian :
wells with the salt water, as to fur-
nish heat enough by its combustion
for evaporating the salt water. The
village of Fredonia, in New York, Fi«- 325\
has for many years been illuminated with this gas, derived
from the saliferous deposits.
452. Preparation. — Marsh gas is prepared by treating
equal parts of acetate of soda and solid hydrate of potash
with one and a half parts of quicklime. The materials are
ground separately, well mingled, and strongly heated in a
retort of hard glass protected by a thin sand-bath of sheet-
iron. The acetic acid C4H404 of the acetate is decomposed
by the potash, which removes from it 2 equivalents of car-
bonic acid, and marsh gas is evolved, thus :
Acetic acid C4H4O4 = Carbonic acid, 2 equivalents C» 04
Marsh gas C»H4
C4H4O4
C%H404
Give their composition. 451. What is marsh gas ? How may it bo
collected? What other natural sources are named ? 452. How is it pro-
pared ? Give the reaction.
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268
NON-METALLIC ELEMENTS.
The lime preserves the glass of the retort from the action
of the potash. •
453. Properties. — Marsh gas is colorless, inodorous,
slightly absorbed by water, and is respirable when mingled
with common air. Its weight is about half that of air, or
'559, and 100 cubic inches weigh 17*41 grains. It burns
with a yellow flame, giving as the products of combustion
water and carbonic acid. Mingled with common air, it
forms an explosive mixture, which collects in large quantities
in the upper part of the galleries of coal-mines, giving origin
to fearful explosions and the destruction of many lives of
miners. Twice its volume of oxygen burns it completely.
It has never been liquefied. In a tube of porcelain, at full
redness, it is decomposed, carbon is deposited, and hydrogen
evolved. With moist chlorine in the sunlight, it forms
carbonic and chlorohydric acids, but is not affected by it in
the dark. It is composed in 100 parts, of hydrogen 25,
vapor of carbon 75 \ or by volume, of
2 volumes of hydrogen = 0*696X2= 0*1392
and \ volume of carbon vapor = *829 -~ 2 = 0*4145
Theoretical density of marsh gas 0*5537
454. Olcfiant Gas, or heavy Curburetted Hydrogen Gas.
— This gas was discovered in 1796, by an association of
Dutch chemists, who gave it the name of defiant, because it
forms a peculiar oil-like body with chlorine. It is prepared
by mixing strong alcohol with five or six times its weight
of oil of vitriol in a capacious retort, and applying heat to
the mixture. The action is complicated, and cannot be well
explained at this time. The gaseous products are defiant
gas, carbonic acid, and sulphurous acid. The alcohol is
Fig. 326.
453. What are its properties? What danger arises from it in coal*
mines? How is it composed by volume ? 454. How is it prepared?
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COMPOUNDS OF HYDROGEN.
charred, and at the end of the operation froths up very much.
The gas can be purified by passing it first through a wash-
bottle containing a solution of potash, and then through oil
of vitriol ; the potash removes the acid vapors, and the oil
of vitriol retains the ether, (fig. 326.)
455. Properties. — Olefiant gas is a neutral, colorless,
tasteless gas, nearly inodorous, and having a density of
0-9784; 100 cubic inches of it weighing 30 57 grains. It
burns with a most brilliant white light and evolves much
free carbon. With three volumes of oxygen gas it burns
completely, with a tremendous detonation, which is too
severe even for very strong glass vessels. Bub bles of the mix-
ture may be exploded by a burning paper, as they rise from
beneath the surface of water. Water and carbonic acid are
the sole products of this combustion. It is partially decom-
posed by passing through tubes heated to redness, and much
carbon is deposited. This effect happens in the iron retorts
of city gas-works, in which crusts of pure carbon, sometimes
of great thickness, accumulate from the decomposition of
the gas. 100 parts of olefiant gas contain 200 hydrogen
and 100 vapor of carbon. Thus,
2 volumes of hydrogen weigh 0*1392 14*29
1 volume of carbon vapor....... 0*8290 85*71
0*9672 100*00
Its formula is thence C4H4, and the experimental density
(0*9784) is a near approach to the theoretical.
456. The chlorine compound will be described in the
organic kingdom. It burns with chlorine, forming chloro-
hydric acid, and depositing its carbon in a dense cloud.
Illuminating gas is formed of a union of marsh gas and of
olefiant with some free hydrogen. The power of illumination
is derived from the olefiant gas. Ammonia, its sulphuret,
carbonic acid, tar, and resinous pyrogenic compounds require
to be removed from coal gas before it is fit for use j and this
is accomplished by passing it through water, cooling it in con-
densers, and transmitting it through dry lime purifiers, and
through dilute solution of sulphate of iron to remove HS
and C09.
The other compounds of hydrogen with boron, &c, are
too little known to require description now.
455. What its properties ? How much oxygen burns it ? What are
the products ? How decomposed ? What is its composition ? 456. Whence
its name ? What is illuminating gas ?
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270 COMBUSTION.
Combustion, and the Structure of Flame.
457. Combustion. — This familiar phenomenon is the dis-
engagement of light and heat which accompanies some cases
of chemical union. Nearly all our operations being per-
formed in the atmosphere, the term combustion has come to
be restricted, in a popular sense, to the union of bodies with
oxygen, with development of light and heat. Thus, carbon,
sulphur, phosphorus, &c, are familiar examples of elementary
combustibles, while oil, tar, coal, wood, &c, are compound
ones. The products of the combustion of organic bodies
are all gases or vapors, and are no longer combustible;
while the products of the combustion of iron, phosphorus,
potassium &c, are oxyds, bases, or acids, and generally are
incapable of further change from similar action. Thus, iron
burns brilliantly in oxygen gas, (277,) forming a com-
pound, capable of no further change in oxygen. Iron also
burns in vapor of sulphur, (fig. 232,) but the protosulphuret
of iron so formed is still capable of burning in oxygen.
For such reasons as these, bodies were for a long time di-
vided by chemists into two classes, of combustibles and
supporters of combustion. This mode of arrangement is
now for the most part abandoned. It was radically defective
as a philosophical classification of elements, since it seized
on a single phenomenon accompanying chemical union, and
disregarded all those natural analogies which group the ele-
ments into distinct classes.
458. In all cases of combustion the action is reciprocal.
Hydrogen burns in common air ; but if a stream of oxygen
is thrown into a jar of hydrogen, through a small aperture
at the top, when the latter is burning, the flame is carried
down into the body of the jar, and the oxygen will continue
to burn in the hydrogen, as it issues from the jet. In this
case the oxygen may be said to be the combustible, and the
hydrogen the supporter. The simple statement in both
cases is, that oxygen and hydrogen combine, and combus-
tion— that is, the disengagement of light and heat — is the
consequence. (Daniell.) The diamond burns in oxygen gas,
but the latter is as much altered by the union as the former;
457. What is combustion ? IIow is the term restricted ? What division
pf elements was founded on this phenomenon ? 458. What of *he r#-
flinrocal nature of combustion ? What of light and heat evolved ?
Digitized by VjOOQ IC
COMBUSTION. 271
and wo cannot therefore say whether the oxygen or the
carbon is the most burnt. Heat and light attend this union :
but the carbon of the human body is as truly burnt in the
lungs by the atmospheric oxygen, as is the fuel on our fires.
The product of this combustion, the carbonic acid, thrown
out by the lungs at every exhalation, is the same thing as
the carbonic acid which is discharged at the mouth of a
furnace. In the case of the animal body, the combustion is
so slow that no light is evolved, and only that degree of heat
(98° to 100°) which is essential to vitality. The term
combustion must have, then, a chemical sense vastly more
comprehensive than its popular meaning. The rust which
slowly corrodes and destroys our strongest fixtures of iron,
and the gradual process of decay which reduces all structures
of wood to a black mould, are to the chemist as truly cases
of combustion as those more rapid combinations with oxy-
gen which are accompanied by the splendid evolution of
light and heat.
The heat produced by combustion has received no satis-
factory explanation. We know that any change of state in
a body is accompanied by an alteration of temperature.
When two liquids become solid, we can better understand
why heat should be produced, (124.) But why the union
of carbon and oxygen, or of oxygen with hydrogen, to
form a gas, should evolve such intense heat as to fuse the
most refractory bodies, is as yet unexplained.
459. Bodies become visible in the dark at about 1000°
of heat This fact has been lately confirmed by the re-
searches of Draper, on the shining by heat of a strip of
platinum in the dark, when heated by a current of voltaic
electricity. It is true of all bodies capable of being heated,
whether solids, or fluids, as melted metals. It is impossible
by any means to render a gaseous body visibly red. A
coil of platinum wire suspended in the current of air escap-
ing from an argand-lamp chimney is at once heated to red-
ness, while, as every one knows, the hot air itself is entirely
invisible. Combustible gases heated to a certain point in
the air, take fire and burn, as when we apply to our gas-
burner the flame of a match. The color of red-hot bodies de-
pends on the temperature. Yellow light begins to be evolved
What chemical extension is given to the term ? Whence the heat
evolvod in combustion ? 459. At what temperature do bodies become
Tisibleinthedark?
Digitized
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272 NON-METALLIC ELEMENTS.
at about 1325°, and at 2130° all the colors of the spec
tram were- observed by Draper in the light viewed by a
prism as it came from incandescent platinum. A full white
heat, seen by day-light* is supposed to be at least 3000°.
The increase of brilliancy in the light from hot bodies is at
a much higher ratio than the temperature. Thus, the same
observer found the brilliancy of light at 2590° more than
thirty-six times as great as it was at 1900°.
Of Flame.
460. The structure and nature of flame deserve particu-
lar notice. If we look attentively at the flame of a
candle, (fig. 327,) we see that it is formed of several
distinct parts, wrapped, so to speak, conieally about
each other. 1st. There is the interior cone a a', form-
ed entirely of combustible gases, and giving no light.
2d. The cone efgy which is very brilliant, and where
| the gaseous contents of the first portion become
I mingled with atmospheric oxygen ; the hydrogen is
burned, and the carbon, precipitated in minute parti-
cles, reflects light powerfully. And 3d. We see the
I thin outer envelope c d o, where the combustion is
completed, but where there is much less brilliancy of
1 illumination than in efg. In the flame of a gas jet A,
Fig. 327. (fig. 328,) the same parts are recognized, similarly let-
kc tered, simplified by the absence of the candle-wick,
whose place is occupied by the ascending stream of gas.
A section of the candle-flame midway between a a!
would give us three distinct rings, each marked by its
own chemical condition. In the centre is the olefiant
gas of the decomposed fat H, (fig. 329.) The hydro-
gen of this burns first, forming water, and the carbon is
raised by the heat of the burning hydrogen to white-
ness, and fills the space c; while, exte-
rior it, the thin film o is formed from
the union of the carbon with oxygen to
form carbonic acid. Flame may therefore
^ be considered as a hollow cone of ignited
uigT328. combustible gas, covering as with a shell FiS- 329-
What was Draper's experiment ? What is the temperature of yellow
light ? What the brilliancy as compared with temperature ? What is
noticed in the structure of flame? Describe fig. 327. What are the
parts of thj flame ? Define flame.
Digitized
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FLAME.
273
an interior unignited mass of inflammable gas. This is easily
demonstrated by introducing a small tube of glass 6, fig. 330,
into the cone H, by which a portion of the inflammable
gas is led out and may be burnt at the
open end of the tube. In like man-
ner, by bringing a sheet of platinum
foil over the flame of a large spirit-
lamp, it will be heated to redness in a
ring on the outer circle, while the
centre remains black, showing that the
interior is comparatively cold. Phos-
phorus fully ignited in a metallic
spoon is at once extinguished by im-
mersion in the interior of a volumin-
ous flame, like that from alcohol, burn-
ing in a small capsule. The air is shut Fig. 330.
out by the screen of flame : the phosphorus, finding no oxy-
gen, goes out, but may be seen fused in the spoon: bringing
it again to the air, it is rekindled, and so on.
461. A high temperature, it will be easily seen, is an
indispensable condition for a perfect and brilliant combus-
tion, as the light reflected from the ignited carbon is vastly
greater at $000° than at 2500°, (459.) A plentiful supply
of oxygen is of course the antecedent of a perfect combus-
tion. The candle or lamp becomes smoky whenever these
conditions are imperfectly fulfilled — as when the
wick of a candle becomes too long and reduces the
temperature of the flame below the point of bril-
liant combustion, supplying at the same time a
superabundance of material. The candle must
then be snuffed; or it may be provided with a
flat plaited wick, as in fig. 331, which bends out-
ward as it burns, and coming in contact with the
air, consumes as fast as it protrudes. In all flames
like that of the candle, when the air has contact
only on one side, combustion is very imperfect. A
more rapid and abundant supply of oxygen is the
object in the construction of the argand and solar
lamps and all similar contrivances. F>g- 331.
462. This is accomplished in the argand burner by
How is it demonstrated by fig. 330 ? What other experiments arc given P
461. What are the conditions of perfect combustion? Why is a candle
an imperfect illumination ? What is the principle of the argand burneri ?
18
M
Digitized
byGoogk
274
NON-METALLIO ELEMENTS.
employing a circular wick abed (fig.
332) arranged between the metallic tabes
through the centre of which g h a draft of
air rises, as shown by the central arrows,
The draft is made more powerful by
using a glass chimney, contracted at D 0
so as to deflect the ascending outer cur-
rent of air strongly against the flame.
^ Thus, at the same instant, fresh supplies
^\c of oxygen are brought in contact with
the inner and outer surfaces of flame,
which still retains the same relation of
parts as before. The heat of combus-
tion is enormously increased by these
means; and with the same amount of
fuel, a much more brilliant light is pro-
Fig. 332. duced. In the common double-current
spirit-lamp, employed in the laboratory for high heats, the
construction is similar, a metallic
chimney replacing the glass. A section
of this lamp is seen in fig. 333. Dr.
C. T. Jackson has described a modi-
fication of the double-current spirit- rHKHv
lamp, in which a blast of air from a H~ D ,
bellows is introduced within the inner
tube. The arrangement is such »hat
the blast
issues in
a narrow ring, con-
centric with the wick
and in close contact Fi** 333*
with it. Properly managed", this lamp
forms the most powerful lamp-furnace in
use. The invention in fact ap- r^\
plies the principle of the mouth
blowpipe to the argand lamp.
In places where gas is used, k
the gas-lamp, (fig. 334,) fod \
Fig. 334. by a flexible pipe and supplied
with a metallic or mica chimney, leaves nothing
to be desired for a powerful and economical Fis- 335#
Describe fig. 332. Why is the heat increased? What is Jackson*'
lamp ? What the gas-lamps ?
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FLAME.
275
beat. A small glass spirit-lamp, with a close cover, (fig.
335,) to prevent evaporation, is an indispensable convenience
in even the humblest laboratory.
463. The Mouth Blowpipe (fig. 336) converts the flame of
ft common lamp or candle into a powerful furnace. By the
blast from the jet of the blowpipe, the operator turns the
Fig. 336.
flame in a horizontal direction upon the object of experi-
ment, at the same time that he supplies to the interior cone of
combustible matter a further quantity of oxygen. The flame
suffers a remarkable change of appearance as soon as the blast
strikes it, and the inner blue point b has very different chemi-
cal effects from the exterior or yellow point c, (fig. 337.)
Immediately before the
exterior flame is a stream
of intensely heated air,
which is capable of pow-
erfully oxydizing a body
held in it, and this point
is therefore called the
oxydizing flame. The FiS* 337*
inner or blue point b a is called the reducing flame, and in
it all metallic oxyds capable of reduction are easily brought
to the metallic state or to a lower degree of oxydation. Be-
tween the outer and inner flames is a point of most intense
heat, where refractory bodies are easily melted. Charcoal
is generally employed to support bodies before the blow-
pipe flame, when we would heat them in contact with car-
bon. Forceps of platinum are used to hold the substance
when it is to be heated alone.
If the substance is to be submitted to the action of borax,
463. What is the principle of the mouth bhw pipe ? What parti
ore noted in the flame before the jet,fig. 337 ? What is the reducing and
what the oxydizing flame ?
■Digitized
byGoogk
276 NON-METALLIC ELEMENTS.
or of carbonate of soda,
or any similar reagent, a
small platinum wire, bent
into a loop at one end,
is used to hold the fused
globule, as seen in fig.
! 338. Then, by varying
Fig. 338. its position in the flame
as above described, we may submit it successively to the
reducing agency of carbon vapor, and oxyd of carbon at bf
to the intense heat of burning carbon at c, or to the power-
ful oxydizing influence of the current of hot air immediately
in front of the point c. The art of blowing an unintermit-
ting stream is soon acquired, by breathing at the same time
through the mouth and nostrils ; and an experienced opera-
tor will blow a long time without fatigue. No instrument
is more useful to the chemist and mineralogist than the
mouth blowpipe. By its means we may in a few moments
submit a body to all the changes of heat, or the action of
reagents, which can be accomplished with a powerful furnace.
Safety Lamp.
464. The temperature of flame may be so reduced by
bringing cold metallic bodies near it as to be extin-
guished. Davy also observed that a mixture of explosive
gases, could not be fired through a long narrow orifice like
a small tube. On these simple facts rests the power of the
" safety lamp" of Sir Humphry Davy to protect the life of
the miner. If a narrow coil of copper wire, (fig. 339,) be
a^ brought over a candle or lamp so as to
Ql encircle it, the flame will be extin-
Fig. 339. guished ; but if the wire be previously
heated to redness, the flame continues to burn. The same
effect will be produced by a small metallic tube. A wire held
in the flame is seen to be surrounded with a ring of non-lu-
minous matter. If many wires, in the form of a gauze, are
brought near the flame of a candle, it will be cut off and
extinguished above ; only a current of heated air and smoko
will be seen ascending, (fig. 340,) while the flame continues
to burn beneath, and heats the wire gauze red-hot in a ring,
marking the limits of the flame. The flame may be relighted
464. What is the effect of a cold body on flame ? What was Davy's
observation ?
Digitized by VjOOQ IC
FLAME.
277
above the gauze, and will then burn as usual, as seen in
fig. 341. Sir Humphry Davy found that a wire gauze
would in all cases arrest
progress of flame,
that a mixture of
the
and
explosive gases could not
be fired through it. A
wire gauze is only a series
of very short square
tubes, and their power
to arrest flame comes
Fig. 340.
from the fact that they cool the gases below their point of
ignition. Happily, the heat required to ignite the carbon
gases is much higher than that which causes the union of
oxygen and hydrogen.
465. The fire, damp or explosive atmosphere of coal-
mines, is a mixture of light and heavy carburetted hydro-
gen, with many times their volume of common air. These
gases, being lighter than the air, are found especially in the
upper part of the galleries of mines, and when the naked
flame of the miner's lamp meets such an atmosphere, a terrible
explosion often follows. These explosions in coal-mines b<w\
destroyed thousands of those whose duties requir- (f\
ed them to submit to the exposure. To avoid these
lamentable accidents, Davy invented the safety
lamp. This is only a common lamp surrounded
by a cage of wire gauze, completely enclosing the
flame, (fig. 342.) When this lamp is placed in an
explosive atmosphere, the gas enters the cage,
enlarges the flame on the wick, and burns quietly,
the gauze effectually preventing the passage of
the flame outward. We thus enter the camp of
the enemy, disarm him, and make him labor for
us. The miner is not only protected by this in-
strument, but is rendered conscious of the danger
by the enlargement of the flame. As long as the
lamp can burn, it is safe to stay, as an irrespira-
ble atmosphere would extinguish the flame. The
powerful blast of wind which sometimes sweeps Fig. 342.
Explain figs. 340 and 341. What is the application ? What peculiari-
ty is noticed of the carbohydrogen gases ? 465. What is the fire damp ?
Where does it chiefly collect? How was Davy's lamp constructed?
What is its action ?
Digitized
byGoogk
278 METALLIC ELEMENTS.
through the mines may render the lamp unsafe, by forcing
the flame against the gauze, until it is heated so hot as to
inflame the external atmosphere. This accident is prevented
by the addition of a glass to cover the sides, the air being
admitted from below through flat gauze discs.
II. METALLIC ELEMENTS.
General Properties of Metals.
466. The number of the metals is forty-eight, of which
about half are entirely unknown, except in the laboratory,
and as the rarest minerals in our cabinets. Of the other
half, only fourteen or fifteen are familiarly known, or pos-
sess in a remarkable degree those qualities of ductility, lustre,
and malleability, which are inseparable from our common
notions of the metallic character.
A metal is an opaque body, of a peculiar brilliancy, de-
scribed as the metallic lustre. It conducts heat and elec-
tricity, and in electrolysis it goes to the negative pole of the
voltaic battery, and is therefore an electro-positive body.
These are the chief characters peculiar to the class.
Metallic Veins.
467. In nature, the metals exist commonly in union with
sulphur, oxygen, and arsenic. A few, as gold, copper, pla-
tinum, and mercury, are found native, or uncombined, or
are occasionally alloyed with each other, as native gold nearly
always contains a portion of silver. When the metals are
combined with sulphur, or other mineralizing agents, by
which their proper metallic characters are masked or con-
cealed, they are called ores. The native metals, gold, cop-
per, platinum, &c, are not properly denominated ores, being
obtained in a metallic state from the sands. The discovery
and extraction of the ores of the metals constitutes the art
of mining. The separation of the metals from their ores, by
heat or other means, is a separate branch of chemical art,
known as metallurgy. Mining demands a minute knowledge
of thej.mineralogical character of the ores of metals and of
466. What is the number of metals ? How many are commonly known ?
What is a metal ? 467. How do the metals exist in nature? What are
-♦res? What is mining? What is metallurgy? What does mining re«
/(uire ?
Digitized
byGoogk
METALLIC VEINS.
279
the earthy minerals with which these are associated; as well
as the mode of occurrence of mineral veins and ore beds, and
the mechanical methods adopted for the raising of the ores
from the earth, their separation from foreign substances, and
their preparation for market.
468. The ores of metals are seldom scattered through the
rocks in a diffused manner, but are usually collected in veins
or lodes, accompanied by quartz, carbonate of lime, and
various other minerals, called the vein-stone, or gangue. The
metal-bearing veins occur more frequently in regions where
primitive rocks abound, as in granite and its associates.
Often, however, they extend from these rocks to those which
rest above them, and are stratified ; showing that the veins
fill fissures in the earth, occasioned by the cooling of its
heated mass, and into which the minerals now filling them
came by injection or infiltration. These fissures usually occur
together, in a degree of order, the veins being more or less
parallel, as seen in
c,c,c,&c.,(fig.343,)
which is an ideal sec-
tion of a metallic
deposit, (the veins
are here seen to
reach from the gra-
nite c to the stratifi-
ed rocks a, a.) Cross
veins, or courses,
often intersect in a
different direction,
as d} e, &c. , and these
have usually a mi- Flg' 343'
neral character entirely distinct, and showing a different age
and origin. At the intersection of veins there is usually
an enlargement of the lode, and often a more abundant
deposit of the metallic ore. It is very rare, if ever, that the
metallic ore fills the vein entirely. It usually forms small
threads running through the vein-stone, now expanding, and
again contracting, as seen in the vertical section of a vein in
fig. 344, where a, b, c show the rocky gangue surrounding
468. How are ores found ? What is a vein-stone or gangue? Wnere
do veins most frequently occur ? Describe fig. 343. Where are veins
enlarged ? How is the ore usually distributed in mineral veins ?
Digitized
byGoogk
•280
METALLIC ELEMENTS.
the metallic ore d, ey /, g. Often the
ore dies out entirely, as at o, c, and is
again renewed farther on. A few
minerals only are found in beds re-
gularly stratified between layers of
other rocks. Some of the ores of
iron are so found, as well as coal and
rock-salt. But the mode of origin
of these last is quite distinct from
that of the ores of the metals. Fig.
345 shows the mode of occurrence
Fig. 344.
Fig. 345.
of rock-salt in masses, filling cavities formed probably by
the solution of minerals previously existing there.
Physical Properties of Metals.
469. The physical properties of the metals include their den-
sity, lustre, color, opacity, malleability,ductility, laminability,
tenacity, crystallization, fusibility, and conducting power.
In density, metals present every variety, from potassium
(•865) and sodium, (-972,) floating on water, to gold (19-26)
and platina, (21*5,) the heaviest bodies known. In lustre they
range from the splendor of gold and of burnished silver, to
the dulness of manganese and of chromium. This property
often depends on the mechanical condition of the metal ;
thus, gold and platinum, as thrown down from solution in fine
powder, are dull yellowish-brown, and black powders, whiqh
show the lustre and color appropriate to the metals only
under the burnisher. The color of most of the metals is
dull white or gray. Silver is nearly pure white ; gold, yel-
Describe fig. 344. What substances are found in beds ? What is showr.
in fig. 345 ? 469. What are the physical properties of metals ? What of
density? What of lustre ? How do mechanical conditions affect lustre ?
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PHYSICAL PROPERTIES OP METAL8. 281
low; and copper and titanium are red. Copper is the basis
of all colored alloys ; being fused with tin and zinc to form
bell and gun metal and yellow brass. To determine the
color of a polished metal accurately, the light must be
reflected many times from its surface, as may be done by
placing two polished surfaces of the same metal opposite
each other, and examining with a prism the light reflected
at an angle of 90° from them. In this way it is found that
the proper color of copper is orange-red ; of gold, after ten
reflections, a beautiful red; of silver, a reddish-white ; of zinc,
a delicate indigo-blue; of bronze, an intense red; of steel, a
feeble violet, &c. In looking into a deep vase of polished
metal, or into a highly polished bronze cannon, or the bore
of a new steel rifle, these tints of color by reflection are seen.
Opacity is not absolute in metals, as is proved in the case of
gold-leaf on glass, through which a beautiful violet-green
light is seen. This light is found by optical experiments to
be truly transmitted light, and not a color caused by the mi-
nute fissures of the gold-leaf. It is worthy of remark that
this greenish color is complementary to the red, which is
the reflected color of the gold.
470. Malleability, or the capability of being beaten by
blows into thin leaves, is found in the highest perfection in
gold, and in a good degree in many other metals. Some
metals are perfectly malleable when cold, as silver, gold,
lead, and tin ; others are malleable when hot, as iron, plati-
num, &c, and are not without this property, though in a
much less degree, even when cold. Some, like zinc, are lami-
nable at a moderate heat, but brittle above and below
it; others, like antimony, are brittle at all temperatures
short of fusion. Gold leaf has been beaten so thin as to
require 250,000 leaves to equal one inch in thickness, or 1,365
such leaves would about equal in thickness one leaf of this
book. Ductility and laminability are properties closely
allied to malleability. Iron, for instance, unless heated,
can not be beaten like gold, but it may be drawn into
fine wire, (ductility,) and plated by rollers into thin sheets,
(laminability).
What of color ? Enumerate colored metals and alloys ? How are
metallic colors accurately determined ? What are thus found to bo the
colors of gold, of copper, of silver, zinc, and bronze ? Is opacity absolute ?
Why not ? What is proved of the green color of gold ? To what is it
complementary ? 470. What of malleability, ductility Ac. ?
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282
METALLIC ELEMENTS.
Metals are rolled in a machine composed of two equal
^ssT'v cylinders of iron or steel, seen in section
i||p!||m in fig. 346. These move in the direction
SI, : ;^J shown by the arrows. During this process,
^ ji^l^, the metal becomes more hard and elastic,
|p|5v owing 10 a rearrangement of its particles.
^:|p|fj Heated to a redness and slowly cooled, it is
lilr again softened, and is then said to be annealed.
Copper is annealed by plunging the red-hot
Fig. 346. metal into water, while the same treatment
renders steel intensely hard.
471. The tenacity of metals is compared by using wires
of the same size of different metals, and ascertaining how
much weight they will sustain. Iron is the most tenacious,
and lead the least. The tenacity of wires TJ<y of an inch
in diameter is equal,
For Iron, to 444 pound*.
" Copper. 300 «
" Platinnm 275 "
" Silver. 171 «
« Gold 137 "
For Zinc, to .....100 pounds.
" Nickel. 07 "
" Tin 32 "
" Lead 24 "
Wires are drawn through smooth conical holes in
a steel plate, (fig. 347,) each succeeding hole
being a little less than its predecessor. In
this way, wires of extreme fineness may be
I drawn from several of the ductile metals. Dr.
I Wollaston succeeded, by a. peculiar method, in
! making a gold wire so small that 530 feet of it
weighed only one grain ; it was only 5^ ^ of
an inch in diameter; and a platinum wire
was made by the same philosopher, of not more
wwvvw of an inch. Metals passed repeatedly through
a wireplate, also become stiff and brittle, as in the rolling
mill.
472. Many metals crystallize beautifully, from fusion, when
slowly cooled, as described for sulphur, (306 ;) bismuth offers
the most remarkable example of this : others solidify without
crystallization, or the traces of crystalline structure are seen
only feebly marked by lines on the surface. Copper, gold,
Fig. 347.
than sTsfon
How are metals rolled? What is annealing? 471. How is tenacity
shown? Gire examples. How is air formed ? 472. What of crystal-
lization?
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CHEMICAL RELATIONS OF METALS. 283
•mlver, platina, and some other metals are found crystallised
* in nature. We can also imitate nature in this respect by the
Voltaic battery, which enables us to procure many metals in
perfect crystals. Iron, brass, and other metals often take on
ft crystalline structure by vibration materially influencing
their tenacity. The fusion points of several metals were
given in § 121.
Many metals are volatile, of which mercury, arsenic,
tellurium, cadmium, zinc, potassium, and sodium are exam-
ples, being volatile below a red-heat. Even gold, silver,
and platinum are raised in vapor by the heat of the voltaic
focus, (198.)
Some metals assume a semi-fluid or pasty condition before
melting, such as platinum and iron, both of which can be
welded or made to unite without solder, when in this soft
state ; lead, potassium, and sodium can be welded in the cold,
as also can mercury, when it is frozen. The conduct-
ing power of some of the principal metals was given in § 88,
and their capacity for heat in § 120.
473. The metals unite with each other to form alloys,
many of which are familiarly known, as $ copper and i zinc
' to form brass. Tin and copper form very various alloys,
according to the proportions employed : 90 copper and 10
tin form speculum metal, which is as brittle as glass and
almost white. The alloys of mercury with other metals
are called amalgams. The fusibility of alloys is often
greater than that of the constituent metals. . Newton's
fusible metal, an alloy of 5 parts lead, 3 of tin, and 8 of
bismuth, is an example of this fact. Lead fuses at 617°,
bismuth at 509°, and tin at 442°, while Newton's alloy fuses
at 203°.
Chemical Relations of the Metals.
474. The metals, as already stated, are positive electrics.
Their affinity for oxygen is universal, but various in degree.
Sodium, potassium, magnesium, and generally the metallic
bases of the alkalies and earths, have such an avidity for
oxygen, that they pass at once to the condition of oxyds on
contact with air. Iron, zinc, copper, &c., are very slowly
How produced by art? What metals are volatile? What is welding?
473. What are alloys? What are amalgams? What of Newton i aietal?
(74. What are the chemical relations of the metals?
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284 METALLIC ELEMENT8.
oxydized, and are soon covered by a coat of oxyd, which
protects the metal from further action. Gold, platinum,
and silver, on the contrary, resist the action of oxygen per-
fectly, and are called, from their unalterable nature, noble
metals.
The metallic oxyds may be divided into three classes :—
1. Basic oxyds, which include the protoxyds generally,
as potash, soda, lime, and protoxyd of iron. Basic oxyds
unite readily with acids to form crystallizable salts. Their
formula is RO.
2. Acid oxyds, which themselves form salts with powerful
bases, and rarely, if ever, combine with other acids. Chromic
acid CrO„ manganic acid MnO„ and other metallic acids
are examples. Their usual formula is ROa or R08.
3. Neutral or indifferent oxyds, which, like alumina Aifi^
may form salts with either powerful acids, or energetic bases.
Their formula is RB08.
475. Besides these there are oxyds which unite neither
with acids nor bases without change, and others which seem
themselves to be true salts. Of the first the common peroxyd
of manganese is an example, MnOfl. Heated with sulphuric
acid it is decomposed, oxygen is evolved, (276,) and sulphate
of protoxyd of manganese is formed, MnO.S08. Suboxyd
of lead PbsO in contact with acids is also transformed into
metallic lead and protoxyd of lead.
Of the saline oxyds we have examples in the oxyds of
manganese, iron, and chromium, whose general formula is
R804. In these compounds two oxyds of the same metal
form, as it were, respectively, acid and base, and we may
write their formulae RO.RaOa. Magnetic iron is an instance.
Certain metals form a great number of compounds with
oxygen, as iron, manganese, and chromium, whose oxyds
may be represented by the general formulae —
R 0 the protoxyd, forming a powerful base.
R*Ot (sesquioxyd,) a feeble base, or neutral, but acting not as an acid.
R Oa the binoxyd, neither base nor acid, but decomposed by acids.
R,04 a saline compound, whose true constitution is RO.R,0».
R 0, a metallic acid ; and also
R*Ot a hyper-acid.
What their affinity for oxygen ? How are the oxyds divided ? What
are basic ? What acid ? What neutral ? Give their general formulas.
What other two classes are named ? Give an example of the first. 475.
Give examples of saline oxyds. 6?lve the general formulae for the oxydf
of iron, manganese, and chromium.
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SALTS. 285
Other metals, as arsenic and antimony, have no prot-
oxyds and form only strong acids with oxygon, by which
feature they strongly resemble some of the metalloids.
476. The chlorids, bromids, iodids, sulphurets, &c. of tho
metals bear a very striking analogy in composition to the
oxyds of the same metals. So true is this, that knowing
what oxyds a given metal forms, we can almost certainly
tell what the composition of its sulphurets, chlorids, &c. will
be. Thus the oxyds of iron being FeO and FeOa08, we find
that the sulphurets of the same metal are FeS and FeflS8,
and the chlorids FeCl and FeyCl3. It might be inferred
from this statement that where these metallic bodies unite
with acids to form salts, there would be the same conformity
among them that is found among their bases, and such we
find to be the fact.
Salts.
477. A salt, as usually understood, is a compound formed
by the union of two binary compounds, which stand to each
other as electro-positive and electro-negative, or as base and
acid. The bases result always from the union of a metal
with a metalloid ; the acids usually are derived from the
union of two metalloids. For example, sulphate of soda
contains for base, soda (NaO,) formed from the metal sodium
and the metalloid oxygen, while the sulphuric acid results
from the union of the two metalloids, oxygen and sulphur.
The salts of metallic acids, as just explained, (475,) constitute
an exception, as the metal is present alike in acid and base.
478. Salts are formed only between members of the same
class, that is oxygen acids unite with oxygen bases, chlorine
acids with chlorine bases, sulphids with sulphids, &c., as sul-
phuric acid with oxyd of iron to form sulphate of protoxyd
of iron.
On the other hand, compounds belonging to different series,
either do not unite at all, or they mutually decompose each
other. Thus, sulphuric acid cannot unite with sulphuret of
potassium, a sulphur base, but mutual decomposition occurs,
sulphydrio acid escapes, and sulphid of potassium is formed.
What metals have no protoxyds? To what are these affined? 476.
What analogy have the chlorids, bromids, Ac. of the metals ? 477 What
is a salt ? How are bases formed ? How the acids ? Give an example.
What are exceptions ? 478. Between what are salts formed ? How do
impounds of different classes act together? Give examples.
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286 METALLIC ELEMENTS.
Or if chlorohydric acid and oxyd of potassium are brought
together, chlorid of potassium and water result; thus,
KO+HCl = HO+KCl.
479. Neutral salts are formed, when there are as many
equivalents of acid engaged, as there are of oxygen in the
base itself. Thus, potash KO has one equivalent of oxygen
and demands, to form neutral sulphate of potash (KO.S08)
one equivalent of sulphuric acid. But one equivalent of SO,
contains three times as much oxygen as there is in the base,
and this is true of all the neutral sulphates. The nitrate
of potash contains dve atoms of oxygen in the acid to one in
the base, and so on.
The same is true also of those acids whicn contain no
oxygen, as the chlorohydric, provided the metallic oxyd dis-
solves in chlorohydric acid without the evolution of chlorine.
For example, peroxyd of iron dissolved in chlorohydric acid
produces water and a perchlorid of iron : 3HC1 and Fe^O,
giving rise to 3 HO and FeaCl8.
480. The binary compounds of chlorine, iodine, &c., with
many of the metals, particularly those of the alkaline class,
have in an eminent degree the properties of salts. Among
them we recognize particularly, the chlorid of sodium, or
common salt, which is, so to speak, the parent of all salts.
If the definition of a salt, just given, (477,) be rigidly
enforced, these bodies cannot be called salts, since, accord-
ing to that view, a salt is a compound of two binary com-
pounds, forming a quaternary compound, (245.) To avoid
this difficulty, two classes of salts have been instituted, the
first of which includes all those binary compounds which,
like common salt, have a metallic base in direct union with
a salt-radical ; and the second includes those salts which,
like sulphate of soda, are supposed to be constituted of the
oxyd of the metal and of an oxygen acid. The first have
'been called the haloid* salts, and the second the ozy-
salts.
479. How are neutral salts formed? What of sulphate of potash ? What
is the oxygen ratio in the sulphates ? How in case of chlorohydric acid ?
480. What is said of binary compounds of chlorine, <fec, with metals?
What of common salt ? What two classes of salts are named ? What is
meant by salt-radical ? What by haloid salts ?
* From halt, sea-salty and eidoi, in the likeness o£
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SALTS. 28?
The term salt-radical includes all the members of tha
oxygen group except oxygen itself, and also those com-
pound bodies which, like cyanogen, act the part of ele*
ments.
481. In stating the constitution of sulphuric acid, (320,)
it will be remembered that the expression S04+H was stated,
in the view of some chemists, to be equivalent to the com-
mon formula S08+HO. It is claimed that all the hydrated
acids are in reality compounds of hydrogen with a similar
radical, and accordingly nitric acid will be NOfl+H, or cor-
responding to chlorohydric acid C1H. One principal objec-
tion to this view is, that these hypothetical radicals have in
general never been isolated. It is, however, true that those
acids which are capable of existing dry and in a separate
state, as sulphuric, (S08,) phosphoric, (P05,) nitric, (N05?)
and carbonic, (COa,) are not acids as long as they remain
dry ; and although they form compounds with dry ammonia,
that these compounds are not salts. Sir Humphry Davy
long ago suggested that hydrogen was the real acidifying
principle in all acids.
482. If the salt-radical theory is finally adopted, all
acids must be considered as hydrogen acids, and all salts as
haloid salts. For example, let us take two common saline
bodies and present them according to these two views.
Old view. New view.
Sulphate of zino .. ZnO 4- SOs Zn 4-S04
Nitrate of soda Na04- N05 Na + NOe
According to the new view, when an acid dissolves a
metal, there is no necessity for supposing water to be decom-
posed. The metal takes the place of the hydrogen, and
the latter is given off in a gaseous form ; or if the oxyd of
the metal is used, the oxygen and hydrogen unite to form
water, and no effervescence ensues.
The apparent simplicity of this view renders it attractive,
and it has been most warmly supported by Profs. Graham
and Liebig, while in this country it has found an able op-
ponent in Dr. Hare.
481. What is said of the formula of SOt? What view of acids is suggested ?
What objection is urged ? What is true of dry S03 Ac. Who formerly
proposed this view ? 482. What will be the constitution of salts in the
new view ? How does a metal then enter into a salt ? Who support
and who opposes this view ?
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288 METALLIC ELEMENTS
The nomenclature of the salts has already been explained,
(251 :) we shall consider the more interesting salt* under
each metal. \
The order in which the metallic bodies are discussed in
the following pages, is not very different from that usually
adopted in elementary works.
CLASS I. METALS OF THE ALKALIES.
POTASSIUM.
Equivalent, 39*2. Symbol, K (Kalium.*) Density, *865.
483. History. — Potassium was discovered by Sir Humphry
Davy in 1807 ; at the same time with its congeners, sodium,
barium, strontium, and calcium. Before that time, the
alkalies and alkaline earths were looked upon as simple
elementary bodies, and were so treated in all chemical
works. Davy found, on passing the electric current from a
powerful voltaic battery through a cake of moistened potash,
(oxyd of potassium,) both electrodes being of platinum, that
violent action followed; oxygen wasevolved with effervescence
at the positive pole, and bright metallic globules, like mer-
cury, appeared at the negative pole, accompanied by hydro-
gen gas. Some of these globules flashed and burned with a
violet light as they reached the air, while others' remained,
and were soon covered with a white film that formed on
their surfaces. These globules were the metal potassium,
whose discovery constitutes one of the most interesting
chapters in chemical history.
Potassium in combination, chiefly as silicate of potash, is
widely diffused over the globe. It forms a part of all fer-
tile soils. The chief source from which it is procured is
the ashes of hard-wooded forest-trees, which take it up from
soils on which they grow. It is also present in sea-water,
as chlorid of potassium, and is consequently found in the
ashes of sea-plants. .
484. Preparation. — The expensive and troublesome
method of procuring this metal by galvanism, has been
What is the nomenclature of the salts ? 483. What is the symbol and
equivalent of potassium ? When, and by whom, and how was it discovered ?
How is this metal distributed in nature ? 484. How is potassium prepared ?
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POTASSIUM.
289
i«_ placed by a much more convenient and productive fur-
nace operation, founded on the decomposition of potasft at
a white heat by charcoal. For this purpose carbonate of pot-
ash is mingled with charcoal. This mixture is best prepared
by ignited cream of tartar in a covered crucible ; a black
mass is then obtained commonly known as black flux, con-
sisting of carbonate of potassa in intimate mixture with
charcoal derived from the burning of the organic acid. Thig
mass is finely powdered, and ^ of charcoal in small frag-
ments is added. The mixture is then placed in an iron
bottle V (fig. 348) laid horizontally in the furnace M G C.
The bottle should be about f full, and well protected with a
refractory lute of 5 parts fine sand and one part fire-clay,
laid on moist, and well dried in the sun. The cover of the
furnace M admits the fuel, the draft 0 is regulated by a
damper, and a temporary front r n closes the side-opening.
A short iron tube a o connects the retort with a copper con-
densing chamber ABC containing naphtha, and supported
on T P S. The heat is gradually raised to the most intense
whiteness. Decomposition of the carbonate of potash
ensues, the free carbon takes the oxygen of the carbonate,
carbonic oxyd (CO) is evolved, and the potassium distils
Describe fig. 348.
collect?
What is the reaction ? Where does the potassium
10
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290 METALLIC ELEMENTS.
over in metallic globules, which condense in the receiver A.
This copper vessel is constructed of two parts B C, as seen in
fig. 349. The upper B enters C, in which the naphtha is
placed. A vertical partition c d divides B
m into two chambers, and two openings a b
opposite each other correspond to the iron
tube a 0, (fig. 348 :) the partition is also
pierced in the same line. The outer opening
b is closed by a cork, and a glass tube g is
adapted to the opening/, (fig. 348,) by which
the oxyd of carbon escapes. This condenser
is kept cold by a constant stream of cold water
directed on its surface, and the collar m n
lg* " prevents this from entering the lower vase c.
The tube a o is very likely to become stopped in the process
by carbon, and, to avoid this accident, the iron rod, (fig. 350,)
^^ moistened in naphtha, is
introduced at b from time
lg' * to time to clear it. The
potassium collects in irregular masses in C, contaminated with
carbon and other impurities, from which it is freed by a
second distillation in an iron retort with a little naphtha, by
which means it is obtained quite pure.
Naphtha is employed in this process because it contains
no oxygen, and does not suffer any change from the action
of the potassium, which is always preserved beneath its sur-
face and out of contact of air.
485. Properties. — Potassium, when unoxydized, is a white
metal with a bluish shade and eminently brilliant. The dull
masses found in commerce show these metallic characters on
the fresh-cut surface ; but the proper color and brilliancy dis-
appear in the air, which instantly tarnishes it. Exposed to
the air it is gradually converted into a white, brittle mass,
(potash.) Fused under naphtha, its metallic lustre and color
are beautifully seen; and a small quantity may thus be forced
between two test tubes, fitting closely the one within the other,
so as to exhibit an extended white or bluish-white metallic
surface, that may be preserved indefinitely under naphtha..
At 32° it is brittle and crystalline, at 60° soft and yielding
to the fingers, between which it may be moulded and welded.
Describe fig. 349. What precautions are required ? Why is naphtha
used ? 485. What are its properties ? How is its metallic lustre seon ?
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COMPOUNDS OP POTASSIUM. 291
Heated in air it takes fire and burns with a violet-colored
flame. At 151° it melts, and below redness it may be dis-
tilled unchanged in vessels free from oxygen.
Its density is only -865, being the lightest metal known.
Consequently it floats on water, which it instantly decom-
poses; appropriating its oxygen to form oxyd of potassium,
while the liberated hydrogen burns, with a portion of the
volatilized metal, with a beautiful violet-colored flame. If this
experiment is conducted on a vase of water
reddened by a vegetable color, (fig. 351,) the
alkali produced changes this color to blue or
green. The heat produced in this experiment
is sufficient to fuse the potassium, which as-
sumes immediately a spherical form and bril-
liant lustre, and is rapidly driven over the
surface of the water by the steam and vapors Fis- 351.
produced about it, forming altogethel Jne of the most pleas-
ing and instructive of chemical experiments. If the quan-
tity of potassium exceeds a few grains, the heat produced
by its action with the water causes an explosion, projecting
the burning metal in all directions. An irritating cloud fills
the air, which is a portion of the alkali (potash) volatilized
by the heat.
486. The uses of potassium are confined to the laboratory,
where, from its energetic affinity for oxygen, it is a powerful
means of research. By its means we are able to decompose
the oxyds of aluminum, glucinum, yttrium, thorium, mag-
nesium, and zirconium, and to obtain the metallic bases of
these compounds. By it also, as before stated, (379,) we
obtain boron and silicon from boracic and silicic acids.
Compounds of Potassium.
Potassium unites with all the members of the first three
classes, forming compounds, several of which are of great
importance in the arts and in pharmacy : of these we can
describe only a few of the most important.
487. There are two oxyds of potassium, the protoxyd KO
and the peroxyd K03. When potassium is heated in a cur-
rent of dry oxygen it takes fire, burns, and leaves a yellowish
residue, which is the peroxyd of potassium. This substance
What is its density ? How does it act on water ? What causes the
motion? 486* What are its uses ? 487. Name the oxyds of potassium.
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292 METALLIC ELEMENTS.
dissolves in water, with the escape of two equivalents of oxy-
gen, and forms hydrate of potash-solution, KO. HO. Heated
with twice its own weight of potassium in an atmosphere of
dry nitrogen, it forms dry oxyd of potassium, thus KOs+
2K = 3KO. This important compound demands our at-
tention.
488. The oxyd of potassium KO is a powerful base, and
forms a large class of salts. With water it forms two distinct
hydrates, KO.HO and K0.5HO, true salts, of which caustic
potash KO.HO, the monohydrate, is the one chiefly interest-
ing. This substance is procured usually by decomposing
pure carbonate of potash, dissolved in 10 parts of water, in
a clean iron vessel, with half its weight of good quicklime,
previously slaked and mingled with so much water as to
form a thin paste, called milk of lime. This is added in small
portions to the potash solution, while the latter is boiling, a
short interval allowed between each addition ; all the lime
being added, the whole is boiled for a few minutes, and then
is removed from the fire and covered up. The lime displace*
the carbonic acid, forming carbonate of lime and caustic
potash. Care is needed to keep the solution dilute, to pre*
vent the caustic potash formed from decomposing the result-
ing carbonate of lime. The success of the operation is
determined by testing a small portion of the clear fluid with
chlorohydric acid, which should occasion no, or only a feeble,
effervescence.
The clear dilute solution is drawn off by a siphon, boiled
away rapidly, (to prevent absorption of COa from the air,),
to an oily consistency in a clean iron or silver vessel, and
finally carried to low redness. The carbonate of potash, if
any remains, then floats as a scum, being less fusible than
the caustic, and may be skimmed off. The fused caustic,
turned out on a plate of copper or iron, hardens into a white
crystalline cake, which is at once broken up and put in close-
bottles. To insure its purity from sulphates and chlorids,
(often present in the original carbonate,) it is dissolved in
absolute alcohol, which leaves the other salts undissolved.
The alcoholic solution is decanted, distilled in a retort, and
evaporated in a silver capsule, fused and cast as before. No*
degree of heat will expel the equivalent of water which
How are they obtained ? 488. What of KO ? What is KO.HO ? How
procured? What the reaction ? How freed from sulphates, lc?
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COMPOUNDS OP POTASSIUM. 293
this hydrate retains. Pure caustic potassa is also obtained
by decomposing sulphate of potash solution by exactly as
much oxyd of barium as is required to saturate it. The re-
action is KO.S08+BaO.HO = BaO.S08+KO.HO.
489. The hydrate of potash is a white solid, with a crys-
talline fracture. It has a great avidity for moisture and is
soluble in half its weight of water. Exposed, it forms a so*
lotion in the moisture of the atmosphere. It is a most
powerful base, decomposing by fusion the silicates of nearly
all metallic oxyds. Cast in cylinders, it forms the caustic
potassa of surgeons, for which use the mixture of caustic
and carbonate of lime with potassa is commonly employed in
pharmacy, under the name of potassa cum cake; and the
crude potash of commerce, cast in cylinders of a brown color,
are sold under the name of lapis infernalis.
The solution of caustic. potash is intensely alkaline, satu-
rates the most powerful acids, restores the colors of redden-
ed vegetable blues, and turns many of them green. It has
an acrid and most disgusting taste, peculiar to alkalies, and,
when strong, attacks all organic matters, dissolving and dis-
organizing them, feeling for this reason soapy to the fingers
on first contact with the solution. With the fats it forms
soaps, true salts, produced between the fatty acids and the
alkaline base. It dissolves silica in its soluble form, (382,)
and even attacks, when concentrated, the glass vessels in
which it is kept. It absorbs carbonic acid completely, and
is employed for that purpose in organic analysis. The
moderately concentrated solution, (sp. gravity 1*2,) as
procured in the process, (488,) is sufficient for laboratory
use. Potash is a fatal corrosive poison.
490. The tests for the presence of potash or its salts are
ehlorid of platinum, an alcoholic solution of which produces
a yellow crystalline double salt of potassium and platinum
in concentrated solutions : perchloric, tartaric, and bydro-
Suosilicic acids also form sparingly soluble salts with potas-
sium and its salts.
491. The chhrid of potassium KC1, is a soluble com-
pound, crystallizing in cubes. It is formed when potassium
is heated in chlorine, and when potash or its carbonate is
489. What are its properties / What are potassa cum calce, and lapis
infernalis? What of potash solution ? What does it absorb ? 490. What
are to tests ? 491. What is chlorid of potassium ?
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294 METALLIC ELEMENTS.
dissolved in chlorohydric acid. It has a saline bitter taste>
is deliquescent, and does not possess the antiseptic properties
of its congener, the chlorid of sodium.
The bromid of potassium KBr is also a soluble cubical
salt, possessing the medical properties of bromine. It is pro-
duced in the mother liquor of the salines, (294,) and has
been sold fraudulently for the iodid of potassium, which it
much resembles, but does not replace in medical use. Chlo-
rine and the stronger acids decompose it with evolution of
bromine.
The iodid of 'potassium KI, often called the hydrio-
date of potashy is a compound of great importance in medi-
cal practice and in photography. It occurs in cubical crys-
tals, which are soluble in J parts of water and in 6 parts of
alcohol of .85. It is obtained when iodine is dissolved in
potash solution to saturation, and also at the same time iodate
of potash, (KO.I05.) The iodid is separated by repeated
crystallization, or if the whole saline mass is ignited, oxygen
is expelled and only iodid of potassium is left. Its solution
dissolves iodine largely and acquires thereby a dark color.
Starch paste, as before stated, is the appropriate test for it.
The Jiuorid of potassium KP, is also a soluble cubical salt,
exactly analogous to the foregoing compounds.
The cyanid of potassium is described in the organic
chemistry.
492. The sulphur ets of potassium are numerous, five of
which are described, viz. KS, KSfl, KSa, KS4, KS5. The
protosulphuret KS is found in an impure state, when an
intimate mixture of 2 parts of sulphate of potash and 1
part of lamp-black are fused together in a crucible. Owing
to the minute division of its particles with the excess of car-
bon, it forms a very inflammable mass, which takes fire on
exposure to air. This has been called a pyrophorus, or
bearer of fire. The protosulphuret of potassium is also
formed by saturating a solution of potassa with sulphydrio
acid, which, evaporated, leaves a white crystalline mass.
From this salt all the other sulphurets of potassium may
be formed.
How different from chlorid of sodium ? What of bromid ? What fraud
has it served ? What sources has it ? What is iodid of potassium ? How
obtained? What importance has it? 492. What sulphurets of potas-
sium are named? How is the protosulphuret formed? What is the
yyropherus ?
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SALTS OF POTASH. 295
The pentasulphuret KS5 is produced most readily by heat-
ing a strong solution of potassa with an excess of sulphur.
A large part of the sulphur is dissolved, forming a deep
yellow liquid which contains pentasulphuret of potassium,
and hyposulphite of potassa. The pentasulphuret of potas-
sium in the solid state has the old name of liver of sulphur^
and its solution is used in diseases of the skin and as a de-
pilatory.
493. When potassium is heated in dry ammonia, an olive-
green compound is formed, (K.NHfl,) which when heated
evolves ammonia and leaves a dark gray powder resembling
graphite, which is a compound of nitrogen and potassium,
having the formula KflN. The other compounds of potas-
sium, with phosphorus, carbon, boron, &c., are comparatively
unimportant.
Salts of Potash.
494. The salts of potash are numerous and important.
We shall, however, mention now only the carbonates, sul-
phates, nitrate, and chlorate. As it will be altogether im-
possible to give even the names of all the salts of the metals,
we must content ourselves with a selection of the most im-
portant and interesting.
495. Carbonates of Potash. — There are three carbonates
of potash, the neutral carbonate KO.COfl, the sesquicarbonate
K0.JC03, and the bicarbonate K0.2COa.
The neutral carbonate KO.COfl is procured from the ashes
of plants, and in an impure form is made on a great scale in
America, under the names of pot void pearl ashes, which are
the alkali as obtained from the lixiviation and combustion
of the ashes of forest-trees.
The crude carbonate of potash of commerce is contami-
nated by silica, sulphate of potash, and chlorids of potassium
and sodium. The latter impurity is frequently added in the
process of manufacture, either through ignorance or from
fraudulent motives. The best potash is made by using hot
water to lixiviate the ashes, in small leach-tubs. The brown
mass left by evaporating the lixivium to dryness in iron
How is pentasulphuret of potassium formed? What uses has it?
493. What is the action of dry ammonia with K ? 494. What salts of
Ktash are formed ? 495. What carbonates ? How is the neutral car-
nate obtained ? What are pot and pearl ashes ? What impurities hag
the crude article? How does "pearlash" differ from "potaahl"
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296 METALLIC ELEMENTS.
kettles is the potash of commerce. This is moderately cal-
cined to hum off the coloring matter, when a spongy mate
of a fine light blue color is left, which is the pearlash.
Several samples of American potash examined by Dr. L.
C. Beck, yielded 73-6, 74-6, 75 and 769 per cent of car-
bonate and hydrate of potash; from 6 to 15 per cent, of
chlorids of potassium and sodium ; with from 1 to 15 per
cent, of insoluble matter, consisting of silica and the oxyde
of iron and manganese, with lime, alumina, &c., being the
ingredients derived from the inorganic parts of the plant.
496. The pure carbonate is obtained by calcining the
cream of tartar, (acid tartrate of potash,) and dissolving out
the carbonate from the coaly mass by water. The filtered
solution is evaporated to dryness in a silver capsule, and the
salt obtained pure.
The carbonate of potash has a strong alkaline taste, turns
blue cabbage or dahlia-paper green, and is somewhat caustic;
it dissolves in about twice its weight of water, forming a so-
lution, which is much used in the laboratory. It crystallizes
with difficulty, and takes up two equivalents (20 per cent.)
of water in so doing. It is quite insoluble in alcohol. It is
a very deliquescent salt, and must be kept in well-stopped
bottles. Its solution acts as a poison if taken in a concen-
trated form. It usually retains a trace of silica, which is
soluble in the concentrated solution.
Bicarbonate of Potash K0.2COs is formed by passing a
stream of carbonic acid gas through a cold solution of car-
bonate of potash. It crystallizes in large and beautiful
crystals, referable to the right rhombic system. These
crystals contain 9 per cent, of water and have the 'formula
K0.2COfl-|-HO. Four parts of water dissolve it; the solu-
tion has an alkaline taste and reaction, but is not caustic ;
by heat it is converted to the simple carbonate, and it loses
a portion of carbonic acid by solution in hot water.
497. Alkalimetry. — The value of commercial samples of
the carbonates of potassa and soda is determined by the
process of alkalimetry, which consists in ascertaining how
much dilute sulphuric acid of a standard strength is required
to neutralize, exactly, a known weight of the sample exa-
What is the composition of commercial potash ? 496. How is pure car-
bonate obtained? What are its characters? How is the bicarbonate
•btained ? What its form and character ? 497. "VYhat is alkalimetry ?
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SALTS OF POTASH.
mined. The strength of the acid is such that 100
k by measure will exactly saturate 10 parts by weight o!
pure alkaline carbonate. It is foreign to our present pur-
pose to give the full details of this process.
498. Sulphate of Potash, KO.SO?.— This salt is prepared
by neutralizing a concentrated solution of potash by strong
sulphuric acid, added drop by drop. It is also a result of
many processes in the arts. It fuses at a red heat without
change. It is an anhydrous, crystallized salt, which decre-
pitates with heat, and has a density of 2-4. This salt requires
100 parts of water to dissolve 8-36 parts at 32°, and 0-096
parts more of the salt dissolve for every degree above that.
It is one of the hardest of the saline bodies. It is wholly
insoluble in alcohol.
Bisidphate of Potash K0.S08-fH0.S08 is a result of the
nitric acid process (334) when a double equivalent of suk
phurio acid is used. It is properly a double sulphate of
potassa and water. It is formed also when sulphate of
potassa is added to its own weight of S08. It fuses at 392°
without change and without loss of water. A higher heat
expels one equivalent of sulphuric acid. It is decomposed
by absolute alcohol, leaving KO.S08. It is dimorphous,
one of its forms being identical with crystallized sulphur.
The solution is strongly acid, and acts on bases nearly as
powerfully as if potash were not present. When this salt is
exposed to air, beautiful silky crystals, resembling asbestus,
effloresce upon its surface. These are sesquisulphate of
potash 2KO.S08+HO.S03.
499. Nitrate of Potassa; Saltpetre; Nitre; KO.NOs.
This important salt is a natural product in the hot and dry
regions of India and South America, being formed by the
gradual decomposition of animal matters in the soil. It is
also formed artificially by heaping together beds of old
mortar and earth with dung and other animal matters, and
occasionally wetting the mass with fermenting urine. In
the Mammoth Cave in Kentucky, and other caverns, the
soil on the floors becomes strongly impregnated with nitrate
of lime, which is decomposed by wood ashes, and yields
Give the principle of the process. 498. What is sulphate of KO ?
Give its properties, Ac. Give the formula for bisulphate of potash.
What is its proper name ? Give its properties. What is sesquisulphate
of KO? Hoir produced? 499. What is KO.NO,? How formed and
found ? How formed artificially ? What the origin of the NOs?
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298 METALLIC ELEMENTS.
nitrate of potassa. In all these cases, the nitre is obtained
by lixiviating the nitrous earth with water, evaporating and
crystallizing the solution, redissolving and crystallizing a
second time, until the salt is obtained pure. Nitre also
crystallizes from the juices of some plants.
It appears that the nitre of caverns must come from the
union of the elements of the atmosphere, under the influence
of carbonate and nitrate of ammonia, always found to some
extent in the air. Rain water usually contains a trace of
nitrate of ammonia, produced, as is supposed, by the union
of the elements of the air by natural electricity, (§ 331 and
fig. 252.)
500. Properties. — Nitre crystallizes in long, six-sided
prisms, with dihedral summits, derived from the right
rhombic prism. Its density is 1*94. It is anhydrous, and
fusible at about 660° : at a higher temperature it is decom-
posed, yielding oxygen and nitrite of potassa. It is unaltered
in the air and insoluble in alcohol, but dissolves in about 3
parts of water at 60°. In hot water it is much more soluble,
100 parts of water at 206-6° dissolving 236 parts of the salt.
Its solution has a cooling taste, and is slightly bitter. It
is an antiseptic, and is used in the brine for preserving
meats, to give a fine red color to the flesh.
Nitrate of potassa (as well as nitrate of soda) has been
much esteemed as a manure. It is employed also to pro-
cure oxygen, (275,) and the best nitric acid is made from
it, (334.)
501. The great quantity of oxygen contained in nitre,
and the ease with which it parts with it, render it a power-
ful means of oxydation. Fused on a coal it deflagrates bril-
liantly. It is the chief constituent of gunpowder, imparting
oxygen to the carbon and sulphur in that mixture, to form
with explosive energy those gases which are generated by
the combustion of the materials. It is also much used in
all pyrotechnic mixtures, as well as to deflagrate and scorify
metals. The surface of silver-ware is often scorified by nitre,
which burns out the alloyed copper, and leaves a surface of
pure silver. Good gunpowder is composed very nearly of
1 equivalent of nitre, 3 of carbon, and 1 of sulphur. Thus
How is it procured from the nitrate of lime ? 500. What are the pro
perties of nitre ? 501. What renders nitre a valuable reagent? What ii
an antiseptic ? Of what is nitre the chief constituent ?
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SALTS OF POTASH. 299
the powder used in war has the following composition in
different countries : —
Sulphur 11-9 12-5 11-5 10 9 9-9
Charcoal. 13-5 12-5 13-5 15... 16 14-4
Nitre 74-6 75- 75- 75 75 75-7
Much of the explosive energy of gunpowder depends on
its granulation ; a fine dust, of the same composition with
powerful powder, burns with a rapid deflagration, but with-
out explosion. The constitution of gunpowder is varied
according to the use for which it is intended. Thus, 20
sulphur, 18 charcoal, and 62 nitre, are used for blasting-
powder in mines, and its combustion may be rendered still
slower by mixing it with several times its bulk of sawdust.
The effect then is more powerful in moving large masses of
rocks.
The gases formed in the combustion of gunpowder are
carbonic acid and nitrogen, while sulphuret of potassium
remains as a solid residue. The combustion of a squib, or
moist gunpowder, gives a much more complicated result;
nitric oxyd, sulphuretted hydrogen, carbonic acid, carbonic
oxyd, nitrogen, and other products being formed.
502. Chlorate of Potash, K0.C105.— This salt is the salt
already named (275) as the best source of pure oxygen gas.
It is formed by passing chlorine gas through a strong solution
of carbonate of potash, chlorate of potash and chlorid of po-
tassium being formed, the chlorate being easily crystallized
out by its less solubility. The carbonic acid escapes. The
reaction is between 6KO.COa -f 6C1 = 5KC1 + KO.C104
+ 6C(V
503. Properties. — Chlorate of potash crystallizes in flat,
pearly tables, referable to the oblique rhombic prism. Water
at 32° dissolves only 3-3 parts in 100; at 60° only 6 parts,
while boiling water dissolves nearly 60 parts ; it is therefore
much more soluble in hot than in cold water. It is insolu-
ble in alcohol. Its taste is cooling and disagreeable, resem-
bling nitre. It fuses at 750° ; above that heat, oxygen is
given off, and chlorid of potassium left behind. It is a most
What is tho constitution of gunpowder in different countries ? On what
does its explosive energy depend ? What are the products of its combus-
tion ? If wet, what are they? How is blasting-powder made more effi-
cient? 502. What is chlorate of potassa, and how formed? 503. What
are its properties ?
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800 METALLIC ELEMENTS.
energetic oxydizing agent. It forms explosive lpixtures witJl
nearly all combustible bodies.
504. With sulphur and charcoal it forms a compound that
explodes by friction, or by a drop of sulphuric acid, and was.
formerly much used in the preparation of friction matches.
With sulphur alone, it detonates powerfully when wrapped
in a paper and struck by a hammer. With phosphorus its
reaction is extremely violent ; a deafening explosion follows
the slightest compression of the ingredients, and burning
phosphorus is projected in all directions. Its large con-
sumption in the preparation of matches has rendered it a
cheap salt.
Ail attempts to form a gunpowder of chlorate of potash
have failed, the action of the mixture being so violent as to
rend asunder the arms employed. A mixture of sugar and
chlorate of potash is instantly inflamed by a drop of sulphu-
ric acid, and burns with the violet color which belongs to all
the salts of potassium.
The characters of the salts of potash are the same with
reagents as those of potassa before given, (490.) The salts
of the alkalies are distinguished from all other metallic salts
by yielding no precipitate to an alkaline carbonate. All the
potash salts form with sulphate of alumina a crystalline
double sulphate of potassa and alumina — common alum —
crystallizing in octahedrons.
SODIUM.
Equivalent, 23. Symbol, Na. Density, -972.
505. Sodium was discovered by Davy soon after the dis-
covery of potassium, and in the same way. It is now pre-
pared by a process quite similar to that already described
(484) for potassium ; the carbonate of soda being used in
place of the carbonate of potassa.
This metal forms more than 40 parts in 100 of common
salt, and is also frequent in various combinations in the
mineral kingdom. The ashes of sea-plants afford crude
What its solubility? What is its reaction with combustibles? 604.
Why not fit for gunpowder? What color does it burn with? What are
the characters of potash salts? What compound do they form with
Alumina? 505. Give the history and distribution of sodium. How
procured ?
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SODIUM. 301
carbonate of soda, in place of the carbonate of potash pro-
cured from land-plants.
506. Sodium is a white metal, with a silvery brilliancy,
and much resembles potassium in its general properties. Its
color is much whiter than that of potassium, and its dis-
position to tarnish less. Its density is *972, and it melts at
194°. At common temperatures it is harder than potas-
sium, but is easily moulded in the fingers. It does not in-
flame on cold water, unless in masses of considerable size,
but moves about rapidly, fused into a brilliant sphere, until
it is all consumed. It may be alloyed with potassium by
simple pressure, and is then inflamed on water, or alone on
hot water, burning with a bright yellow light, characteristic
of sodium, and strongly contrasted with the violet color of
the potassium flame. The same color is seen when a piece
of soda-glass, or any mineral containing soda, is held in the
flame of the blowpipe ; the flame is instantly tinged yellow.
Exposed to the air, sodium soon falls to a white powder of
oxyd of sodium.
. The compounds of sodium are so similar to those of potas-
sium that we can pass them with a brief notice.
The oxyds of sodium and their hydrates are the same in
composition as those of potassa.
507. The hydrate of soda, or caustic soda, NaO.HO,
is procured by decomposing the carbonate by quicklime, in
the same manner as has already been described for caustic
potash, (488.) It is a powerful alkaline base, very soluble in
water, and deliquescent in moist air. It forms a white
crystalline cake, resembling potassa. It is a corrosive and
energetic poison. All its salts are soluble, which renders it
somewhat difficult to detect its presence in solution.
508. CMor id of Sodium, or Common Salt, NaCl. — This
familiar and abundant substance is too well known to need
much description. It is formed when sodium burns in
chlorine gas, as well as when soda, or its carbonate, is neu-
tralized by chlorohydric acid. In Poland, Austria, Spain,
Sicily, and Switzerland, extensive beds of pure rock-salt are
found, which are regularly mined. Common salt forms
about 27 of every 1000 parts of sea-water, and in warm
506. What its properties? What is the color of its flame? What of
its compounds ? 507. What is NaO.HO ? How procured ? Give its pro-
perties. What of its salts? 508. What is NaCl? How artificially
formed ? How found in nature ?
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802 METALLIC ELEMENTS.
climates, especially in the West Indies, sea-water is evapo-
rated in large quantities by the sun's beat, to obtain salt.
Numerous saline springs are found in New York, Ohio,
Kentucky, and other places in this country, which afford
vast quantities of salt by evaporation. The brine springs in
Onondaga county, New York, are among the most valuable,
and have been worked since 1789. Their water contains one-
seventh part of dry salt. The water of the Great Salt Lake,
in Deseret, contains 200 parts of salt in 1000, or over Hh
of its weight. This salt is nearly pure. The Dead Sea has
a still greater concentration, (§ 544.)
Common salt crystallizes in cubes, which are anhydrous,
and crackle, or decrepitate, when heated, owing to water
mechanically entangled in them. Salt forms singular
hopper-shaped crystals, (fig. 352.) These are produced on
the surface of the evaporating brine, and
grow by increase of the outer edges, as
gravity sinks them constantly, a trifle
below the surface of the fluid, each ad-
ditional row of particles being built upon
Fig. 352. the upper and outer edge of the last. It
requires 2*7 parts of water for its solution, and it is equally
soluble in hot and cold water. In pure alcohol it is scarcely
at all soluble. Its density is 2*557. It fuses at redness,
and sublimes in vapor at a higher temperature. It is em-
ployed for this reason to glaze earthenware, since its vapor
is decomposed by the oxyd of iron of the clay, chlorid of
iron being driven off, while soda unites with the silica of
the clay to form the glaze.
The bromid, iodid, and sulphurets of sodium resemble the
corresponding compounds of potassium, and the two former
likewise crystallize in cubes.
509. Neutral Sulphate of Soda, Glauber's Saltf NaO.
SO8+(10HO). — This familiar salt is found abundantly in
commerce in large crystals, which contain more than half
their weight of crystallization water, viz :
1 eq. anhydrous sulphate of soda 71 44*10
10 " water 90 55-90
1 " crystallized sulphate of soda 161 100*00
How much in sea water ? in salines ? in the Great Salt Lake ? "What
of its crystallization ? How are the hoppers formed ? How soluble ?
Its density ? Why used to glaze pottery ? 509. Give the formula fof
Glauber's salt What is its composition ?
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COMPOUNDS OF SODIUM*
303
It fuses at a moderate temperature in its own water *nd
leaves, on heating, anhydrous sulphate of soda. Expo»"l
to air, the crystals of Glauber's salt efflo-
resce, and fall to powder, from loss of 822
water.
BBIMI
"■III
s»S :::
HIS H?
sai: ssss
■■■■
jy»
If its solution is heated above
93°, anhydrous sulphate of soda is
thrown down. The solubility of sul-
phate of soda presents very remarkable
anomalies. Below 32° it is slightly
soluble. At 32°, 12 parts dissolve in 100
parts of water : the quantity dissolved
increases very rapidly with the tempe-
rature up to 93°, which presents the
maximum of solubility of the salt, being
322 parts in 100 of water. Above that
point the solubility diminishes rapidly
with each increment of temperature,
until at 218° it has diminished to 210 12
parts in 100 of water. The line ABC 320 as0
on the diagram (fig. 353) illustrates Fig. 353.
the relations of solubility and temperature in this salt at a
glance. The vertical divisions O to O' register the range of
temperature from 32° to 218°; the horizontal ones O (Vindi-
cate the degree of solubility, which reaches 322 parts at 93°.
The curve of solubility then descends from B to C, when
210 parts are dissolved at 218°. The cause of this sud-
den diminution of solubility, is the decomposition of the
hydrous salt in solution at that heat, and the precipi-
tation of a portion of anhydrous sulphate of soda. A solu-
tion of Glauber's salts saturated at boiling heat in a vessel
capable of being corked while boiling, and suffered to cool,
will often crystallize completely on withdrawing the cork,
a change from the fluid to the solid state occasioned by the
concussion of the air. The same thing happens if a small
crystal is dropped into a saturated solution of the salt,
(41.)
Sulphate of soda is a familiar aperient. In the arts, its
chief use is in the preparation of carbonate of soda, as will
be presently described. It is a result, on a large scale, of
How does it fuse ? How if exposed ? How does it dissolve in water
it different temperatures ? What is its curve of solubility ? Describe
the diagram 353. How is its solution in vacuo crystallized ? What is ill
use in .the arts ?
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AOi METALLIC ELEMENTS.
the preparation of cblorobydric acid, (426.) The other
sulphates of soda require no mention at present. The solu-
tion of sulphate of soda (12 parts) in strong chlorohydrio
acid (10 parts) produces cold enough to freeze a considerable!
quantity of water in summer.
510. Carbonate of Soda, NaO. COs. — Soda replaces in the
ashes of sea-plants the potash found in those of land-
plants. Hence, formerly, the carbonate of soda of com-
merce was procured, almost exclusively, from the ashes
of sea-weeds. This salt is now obtained entirely from
common salt by the process of Leblanc, which will be briefly
described. This process depends on the fact that when
sulphate of soda, carbonate of lime, and carbon are heated
together, carbonate of soda, oxysulphate of lime, and oxyd
of carbon are the products. The reaction is between 2 eq.
of sulphate of soda, 3 of carbonate of lime, and 9 of carbon;
thus, 2(NaO.SOs) + 3 (CaO.COs) + 9C = 2 (NaO.COJ +
(2CaS.CaO)+10CO. The oxysulphuret of calcium is
wholly insoluble in water, which takes out from the pulve-
rized mass only carbonate of soda. This operation is pre-
pared in a reverberatory furnace constructed like the section
seen in fig. 354. The parts A and B receive the mingled
Fig. 354.
materials, (1000 parts of anhydrous sulphate of soda, 1040 of
chalk, and 530 of charcoal powder.) The fire on the grate
F plays upon the charge on the sole of A, and completes
the chemical reaction which was begun in B, where the
charge is first placed : a bridge-wall separates the two. The
workman judges, by the appearance and consistency of a
What freezing mixture does it form ? 510. Give the formula for car-
bonate of soda. How was it procured formerly ? Describe Leblano's pro-
cess? What is the reaction? Describe fig. 354. What gas is formed f
How is the progress of the operation determined?
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SODIIfM. 305
portion withdrawn from time to time, of the progress of the
operation. The oxyd of carbon forms a blue flame over the
surface, which disappears when the reaction is over. The
heat following the arrow, next plays upon solution of car-
bonate of soda in the boiler C, the lixivium of a previous
charge, and evaporates it to dryness, while at the same
time the more dilute solution of carbonate is heated in D,
to be drawn from time to time into C. The steam and pro-
ducts of combustion escape by the chimney 0. .
Carbonate of soda crystallizes in great crystals of an ob-
lique form and containing 10 atoms of water, viz. NaO.
CO3+10HO, equal to 63 parts water in 100 of the salt.
It fuses in its own water of crystallization. The anhydrous
carbonate, as it comes from the furnace, is called soda-ash.
Bicarbonate of soda is procured by exposing soda-ash to
carbonic acid from fermenting grain, as in distilleries, or by
passing this acid into solution of carbonate. It is, so to
speak, a carbonate of soda plus a carbonate of water, or
Na0.C03+H0.C0a. It is not a very solute salt : 100
parts of water take up 8 of bicarbonate. Boiling water
expels one of the equivalents of carbonic acid. This is
the salt used in preparing effervescent draughts.
The sesquicarbonate of soda, Trona, 2NaO.30O3+4HO is
found native in certain lakes in Africa and South America.
It crystallizes in right rhomboidal prisms, unchanged in air,
and little soluble in water. /
511. Nitrate of Soda, Soda Saltpetre, NaO.N05.— This
salt is found in India and South America, where extensive
plains are covered by it, as at Tarapaca in Chili, and Iquique
in Peru. It resembles nitrate of potassa, but cannot be used
to replace that salt in gunpowder, on account of its strong
disposition to attract water from the air. It is much em-
ployed, however, in procuring nitric acid, and also as a fer-
tilizer in agriculture. It is a white salt, crystallizing in
rhombs, specific gravity 2-09, very soluable, with .a cooling
taste, and deflagrates on burning coals with a strong yellow
light. By carbonate of potassa in solution it is immediately
transformed into nitrate of potassa and carbonate of soda.
How is the solution evaporated ? How does the salt crystallize ? How
much water has it? How is the bicarbonate formed? How soluble ?
What is the sesquicarbonate. 511. What is the history of nitrate of soda ?
What does it resemble ? What its use ? How does it act with com-
bustibles ?
20
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METALLIC ELEMENTS.
512 The phosphates of soda correspond to the three eon*
ditions of phosphoric acid (355) before noticed : they are—
1. PkosphateofSoda (tnbasw) H0.2NaO.POs+24HO.—
The common phosphate of soda of pharmacy is prepared by
precipitating the acid phosphate of lime (347) with a slight
excess of carbonate of soda. It crystallizes in oblique
rhombic prisms, which are efflorescent. The crystals dissolve
in four parts of cold water, and undergo the aqueous fusion
when heated. The salt has a pleasant saline taste, and is
purgative; its solution is alkaline to test-paper. When
evaporated above 90° it crystallizes in another form, with
14 instead of 24 atoms of water.
2. Subphosphate of soda 3NaO.POs+24HO is obtained
by adding solution of caustic soda to the preceding salt.
The crystals are slender six-sided prisms, soluble in 5 parts
of cold water. It is decomposed by acids, even the carbonic,
but suffers no change by heat, except the loss of its water of
crystallization. Its solution is strongly alkaline. The study
of these salts by Prof. Graham has greatly enlarged our
views of chemical philosophy.
3. Bipkosphate* of Soda, or Superphosphate, 2HO.NaO.
POs+HO. — This salt may be obtained by adding phos-
phoric acid to the ordinary phosphate, until it ceases to pre-
cipitate chlorid of barium, and exposing the concentrated
solution to cold. The crystals are prismatic, very soluble,
and have an acid reaction. When strongly heated, the salt
becomes changed into monobasic phosphate of soda.
513. Microcosmic salt, or phosphate of soda and am-
monia, (HO.NH4O.NaO.POs+8HO,) is much used in blow-
pipe operations as a flux. It is formed by dissolving with a
gentle heat, 1 part of chlorid of ammonium and 6 or 7 parts
of phosphate of soda, in 2 of water. Chlorid of sodium is
formed, and the microcosmic salt crystallizes out in rhombic
prisms, which lose 8HO by heat. Its fanciful name was
derived from its supposed virtues in promoting fertility in
the impotent.
514. Bibasic Phosphate of Soda, Pyrophosphate of Soda,
2NaO.POs+10HO. — Prepared by strongly heating com-
512. What phosphates are named ? What is the formula of the tribasic?
Give its properties. What is the subphosphate ? What the superphos-
phate ? What of Graham's researches ? What is the biphosphate of
■oda ? 513. What is microcosmic salt ? How formed ? 514. What if
bibasic phosphate ? Give its formula.
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MTHIUM. 307
Bton phosphate of soda, dissolving the residue in water, and
recr ystallizing. The crystals are very hrilliant, permanent
in the air, and less soluble than the original phosphate :
their solution is alkaline. A bibasic phosphate, containing
an equivalent of basic water, has been obtained ; it does not,
however, crystallize.
515. Monobasic Phosphate of Soda, Metaphosphate of
Soda, NaO.POs. — Obtained by heating either the acid tri-
basic phosphate, or microcosmic salt. It is a transparent,
glassy substance, fusible at a dull red-heat, deliquescent,
and very soluble in water. It refuses to crystallize, and
dries up in a gum-like mass.
The tribasic phosphates give a bright yellow precipitate
with a solution of nitrate of silver, and with molybdate of
ammonia : the bibasic and monobasic phosphates afford white
precipitates with the same substances. The salts of the two
latter classes, fused with excess of carbonate of soda, yield
the tribasio modification of the acid.
516. Borax ; Biborate of Soda ; Tincal; Na0.2B03-f
10HO. — Borax crystallizes in right rhomboidal prisms,
which are soluble in 15 or 16 parts of water : the solution
has an alkaline reaction and sweetish alkaline taste. It
loses its water by heat, and being very fusible, is much used
as a flux in metallurgic processes and as a blowpipe reagent.
It is entirely procured from natural sources of boracic acid
already mentioned, and from the waters of several lakes in
Thibet, in which it is dissolved.
LITHIUM.
Equivalent, 6*5. Symbol, L.
517. This very rare metal is a constituent of several
minerals, as spodumene, petalite, lithia-mica : hence its name,
from lithos, a stone. The electrolysis of the hydrate afforded
Davy a white oxydizable metal analogous to sodium. Its
small atomic weight is remarkable.
The oxyd LO is an alkali, but much less soluble than
515. What is the monobasic phosphate ? What are the tests for
tribasic phosphates ? Of the bibasic ? How are the bibasic, Ac, con-
verted to the tribasic form ? 516. What is borax ? What its source
and uses ? 517. What is lithium ? What of LO ? What use for its salts ?
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308 METALLIC ELEMENTS.
potash and soda. Its sulphate is a beautiful salt, and gives
a rosy flame to alcohol. The lithia compounds all give this
tint to the outer flame of the blowpipe. Some of its salts
&ave been used internally with advantage in cases of urio
*cid calculus.
AMMONIUM.
Equivalent, 18. Symbol, NH4, (hypothetical.)
518. Ammonium, NH4. — The compound metallic radical
ol ammonia has never been isolated, although we have reason
to believe in its existence. When a solution of ammonia, or of
sal-ammoniac, is electrolyzed, nitrogen escapes at the -f- side
and hydrogen at the — side, fig. 355 ;
but if the latter pole is made by using
a portion of mercury in the bend of the
tube b, no hydrogen is evolved, but
the mercury swells up, loses itp fluidity,
becomes like soft butter, and gradually
attains many times its original bulk,
having the lustre and general character of an amalgam. A
more simple mode of forming this amalgam, consists in
making a little potassium or sodium combine by heat with
about 100 times its weight of metallic mercury. This alloy,
when placed in a strong solution of sal-ammoniac, begins at
once to increase in volume by the formation of the ammo-
niacal amalgam, until it has attained very many times its
original bulk, and has a pasty, butter-like consistence.
When the alloy of potassium is placed in hydrochloric acid,
the alkaline metal decomposes the acid, forming chlorid
of potassium and evolving hydrogen. If we subsitute for
the acid (chlorid of hydrogen) a solution of chlorid of zino
ZnCl, a like decomposition ensues; but the zinc, instead of
being set free like the hydrogen, combines with mercury to
form an amalgam. The present reaction is precisely similar;
chlorid of ammonium NH4C1 being substituted for the
518. What is ammonium? Give its history. How obtained more
simply than by electrolysis? What is the appearance of the amal-
gam ? What illustration is given from the alloy in HC1 and in ZnCl J
What is the reaction in the present case ?
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COMPOUNDS OF AMMONIA. 309
chlorid of zinc: the ammonium which is liberated com-
bines with the mercury and forms the light pasty amalgam.
It crystallizes in cubes at 32°, whereas pure mercury is fluid
even at a temperature of — 39° F. It is evident that it has
combined with something which has given it new properties.
This is supposed to be the metallic radical ammonium. The
spongy mass, as soon as the electric action ceases, rapidly
suffers decomposition. Ammonia and hydrogen are set free
in the proportion of 1 to 2, and the mercury regains its
original state, unaltered. Berzelius and other able chemists
explain this reaction, on the ground that the ammonia, by
gaining an additional equivalent of hydrogen, assumes the
peculiar character of a metal, and unites with mercury,
forming an amalgam. This hypothetical metal can replace
potassium and sodium perfectly in combination, and is there-
fore isomorphous with them. All the salts of ammonia are,
on this view, derived from this radical, and its union with
the second class gives us a series of bodies analogous to the
chlorids, bromids, &c, of the other electro-positive bases.
Compounds of Ammonium.
519. Chlorid of Ammonium ; Sal-Ammoniac, NH4C1.—
This salt occurs in nature, sometimes quite pure, as at De-
ception Island, and in volcanic districts generally. It was
originally prepared, in Egypt, (443,) by sublimation from
the soot of the burnt camel's dung. This is ^. ^
done in large flasks of glass, (fig. 356,) the sal- ^Cv%$$^>j
ammoniac collects in the upper part, and the qcP***^^
cake is removed by breaking the bottle. It
is always contaminated by organic matters.
It is also obtained largely from the ammo-
niacal waters of the gas-works. It is purified
by evaporating the crude solutions to dryness,
after treating them with a slight excess of
chlorohydric acid to neutralize tho free am-
monia, and subliming the dry mass in iron Fig. 356.
vessels.
What is the product of its decomposition ? What is the explanation
of Berzelius? How are the ammoniacal salts viewed? 519. What if
•al- ammoniac ? How prepared ?
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810
METALLIC ELEMENTS.
It has a sharp saline taste, corrodes metals powerfully, it
soluble in three parts of cold water, and crystallizes from its
solution in octahedrons. The sublimed salt has a fibrous
texture, and is very tough and difficult to pulverize.
The formation of this compound is easily shown by using
the apparatus already figured, (438,) with hydrochloric
acid in one flask and strong ammonia water in other; the
commingling of the dry gases, driven over by heat to the
central bottle, fills it with a white cloud of sal-ammoniac,
HCl+NHg =3 NH4C1. The preparation and properties of
ammonia have already been explained, (444.)
520. Sulphydret of Ammonium, (Hydrosulphuret of Am-
monia,) NHJ3+HS. — This very useful reagent is formed
by passing a long-continued, slow current of sulphuretted
hydrogen from the gas-bottle a, (fig. 357,) through the
bottles d, e, /, g, filled with strong water of ammonia. This
arrangement is a
simple form of
Woulfe's appara-
tus, (fig. 257.) A
single bottle of
ammonia (as d) is
sufficient for all
common pur-
poses. It should
be kept cold. The
ammonia absorbs
p. 357 an enormous quan-
tity of the gas, and
the resulting sulphuret, which has the strong odor of the
gas, is colorless at first, but gradually assumes a yellow
color. It forms numerous salts with electro-negative sul-
phurets, being itself a powerful sulphur base. It is an
invaluable reagent as a precipitant of the metals, and is also
used in medicine.
There are several simple sulphurets of ammonium, but they
are of no particular interest.
521. Sulphate of Ammonia, or Sulphate of Oxyd of
What its properties ? How formed artificially ? 520. What is sulphydret
of ammonium i Describe fig. 357. What is the chemical character of tkU
body ? What its uses ?
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COMPOUNDS OF AMMONIA. 311
Ammonium, NH40.S08+H0. — This salt, which is a pow-
erful fertilizer, is procured in the large way by neutralizing
the ammoniacal liquor of the gas-works by sulphuric acid :
or it may be easily obtained pure by neutralizing dilute sul-
phuric acid with carbonate of ammonia.
522. There are several carbonates of ammonia. The
common sal-volatile of the shops, with a pungent smell and
alkaline reaction, is nearly a sesquicarbonate 2NH40.3COr
Exposed to the air, this salt becomes a white inodorous
powder, which is the bicarbonate. The sesquicarbonate is
a very valuable salt to the chemist. It forms the basis of
the smelling-bottles so much in use. The dry white powder
formed by the contact of dry carbonic acid and ammonia
in an apparatus like figure 319, is a neutral anhydrous
carbonate NH3.C09, very pungent and volatile, dissolving
readily in water.
523. Nitrate of Ammonia, or Nitrate of Oxyd of Am
monium, NH40.N05+H0. — This salt has already been
noticed (338) under the description of nitrous oxyd. Its
crystals resemble nitre, deliquesce in moist air, and dissolve
in 2 parts of cold water, the solution sinking the thermo-
meter to zero, (124.) It deflagrates on burning coals like
nitre, and hence received the old name of nitrum flammens.
524. All the ammoniacal salts are volatilized by a high
temperature, and yield the ammoniacal odor by trituration
with caustic potassa or lime, or by boiling with solutions of
potash. They are all soluble, and give a sparingly soluble,
yellow, crystalline precipitate with chlorid of platinum.
521. What is sulphate of ammonia ? 522. What carbonates are named ?
What one is formed from the union of the gases ? 523. What is nitrate
of ammonia? Give its formula. How decomposed by heat? What if
its frigorifio poiMr? What name had it? 524. What are tests for am-
moniacal salts'
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812 METALLIC ELEMENTS.
CLASS II. METALS OF THE ALKALINE EARTHS.
525. This class includes barium, strontium, calcium, and
magnesium, the bases of the alkaline earths, baryta, strontia,
lime, and magnesia : these are all soluble to some extent in
water, with an alkaline reaction, but differ very much in the
solubility and other properties of their various salts.
BAKIUM.
Equivalent 68*5. Symbol, Ba.
526. Barium is a silver-white malleable metal, easily
oxydized, and melts at a red heat. It was procured by
Davy by a process similar to that which yielded potassium,
&c. It is better obtained by passing vapor of potassium over
baryta (oxyd of barium) heated to redness in an iron tube.
Mercury dissolves out the reduced metal, and the amalgam
is then distilled. It is named, from the striking weight of
its salts, from barus, heavy.
527. Baryta, or Protoxyd of Barium, BaO. — Baryta is
best obtained by decomposing the nitrate at a red heat. It
is a dry, gray powder, which combines with water to form a
hydrate, slaking with the evolution of great heat and even
light. Its density is 5 -45. The hydrate dissolves in two
parts of hot water, or twenty of cold, and crystallizes in flat
tables. The aqueous solution is a valuable test for carbonic
acid.
Sulphate of baryta, or heavy spar, is found abundantly, as
an associate of other minerals, in veins ; and from it, or the
native carbonate of baryta, all the artificial compounds of
barium are formed.
528. The peroxyd of barium BaOa is formed by pass-
ing pure oxygen gas over the oxyd heated to dull redness in
a porcelain tube. It is chiefly interesting as being the means
of procuring the peroxyd of hydrogen, (420.)
525. What are the metals of the alkaline earths ? 526. What is the equi-
valent of barium ? Give its properties. Whence its name ? 527. What
is baryta ? How does it act with water? What its density ? 528. How
is peroxyd of barium formed, and for what used ?
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STRONTIUM. 318
Chlorid of Barium, BaCl-f-2HO. — This salt occurs in
white tabular crystals, containing two equivalents of water,
which are expelled by heat. It dissolves in a little more
than twice its weight of cold water, and the solution is a
valuable reagent for detecting the presence of sulphuric acid.
529. The nitrate of baryta BaO.N05+HO is also a soluble
white salt, which crystallizes in anhydrous octahedrons, and
dissolves in eight parts of cold or three parts of hot water.
Both it and the chlorid are prepared by dissolving the native
or artificial carbonate in the proper acid.
Sulphate of baryta, heavy spar, BaO.SO,, is a mineral
found abundantly in many places in this country, as at
Cheshire, Connecticut. It crystallizes in tabular modifica-
tions of the rhombic prism, often very beautiful. It is also
found massive at Pillar Point, New York. Its specific gra-
vity (4*3 to 4*7) gives it the name of heavy spar. It is quite
insoluble in water or acids, and not easily decomposed. When
strongly heated with charcoal powder, however, it suffers
decomposition, BaO.S08 -f- 4C = BaS -f- 4CO ; carbonic
oxyd is given off, and the soluble sulphuret of barium may
be dissolved out from the coaly mass.
Sulphate of baryta is extensively ground up for a pigment,
being mixed with white-lead as an adulteration.
530. Carbonate of Baryta, BaO.COa, or the witherite of
mineralogists, is a mineral of some interest, and useful as
the chief source of the various compounds of baryta. All
the soluble baryta salts are poisonous, and their presence
may always be detected by sulphuric acid, or a soluble sul-
phate, with which they form the insoluble sulphate of baryta.
The compounds of barium give a peculiar yellow color to
the flame of the blowpipe, different from the yellow flame
of soda.
STRONTIUM.
Equivalent, 44. Symbol, Sr.
531. Strontium is obtained from its oxyd in the same
manner as barium, and, like it, is a white metal, oxydized
Give the characters of the chlorid of barium. For what is it a test?
529. How is the nitrate of baryta characterized? How is heavy spat
found in nature ? Give its formula and properties. 530. What is car-
bonate of baryta ? What character have the soluble salts of baryta ? How
is their presence detected ? 531. How is strontium obtained, and how
characterized ?
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814 METALLIC ELEMENTS.
easily in the air, and decomposing water at common tempera-
tures. There are two oxyds, the protoxyd and the peroxyd
of strontium, similar in properties to the like oxyds of barium.
The sulphate of strontia (celestine) is a rather abundant
mineral, and the carbonate (strontianite) is much esteemed
by mineralogists. They are very similar in properties to
the sulphate and carbonate of baryta.
532. The cMorid of strontium SrCl -f- 9HO is a deli-
quescent salt, soluble in two parts of cold water. It loses
its water of crystallization by heat. Both it and the nitrate
of strontia SrO.N05 are much employed by pyrotechnists
in forming the red fire of theatres and fireworks. All th3
compounds of strontium give a peculiar red tint to the flame
of the blowpipe, while the barytic salts do not. The salts
of strontia are not poisonous.
CALCIUM.
Equivalent, 20. Symbol, Ca.
533. Calcium is a yellowish-white metal, obtained like
barium, and has so strong a disposition to combine with
oxygen that it is difficult to observe its properties.
534. Protoxyd of Calcium, Lime, CaO. — This most valu-
able substance, so well known as quicklime, is procured in
a state of great purity by heating the stalactites from caverns,
or the purest statuary marble, for some hours to full redness
in an open crucible. The carbonic acid and organic coloring
matter are driven off, and oxyd of calcium (lime) nearly pure
remains. Pure lime is a white, very infusible, and rather
hard body, having a density of 3*18. It
has a great affinity for carbonic acid, taking
it from the air and falling to powder, (air-
slaking.) It also combines with water to
form a hydrate, evolving great heat, (slak-
ing.) When this operation is performed
under a glass bell, (fig. 358,) the vapor of
water at first condensed on the walls of
__ the jar soon forms a transparent atmosphere
Fig. 358. of steam, which, when the bell is raised,
What familiar salts of this mtal are found native ? 532. Describe the
ehlorid of strontium. What is it used for ? 533. What is calcium, and
how is it obtained ? Give its equivalent ? 534. What is lime ? IIow
procured ? What its density ? What is air-slaking ? What slaking bj
water f
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CALCIUM. 315
breaks on the air in a dense cloud of vapor. The heat is
greatest when the water is about half the weight of lime
employed. Is sufficiently high often to inflame gunpow-
der. The hydrate CaO.HO is a dry, bulky powder, soluble
in 1000 parts of water, to form lime-water. With water
it forms a milk of lime; a corrosive paste used to re-
move hair from hides. Lime-water is a valuable reagent
and antacid ; it has a disagreeable alkaline taste ; blued
reddened litmus, and absorbs carbonic acid from the air, by
which it becomes milky from precipitation of carbonate of
lime soluble in excess of carbonic acid.
535. Common lime is prepared by heating limestone (car-
bonate of lime) in large stone furnaces, filled from the top
with the limestone and fuel ; the fire is kept up constantly,
by renewed charges of the materials at top, while the pre-
pared caustic lime is drawn out at the bottom. The carbonic
acid is much more rapidly expelled when the vapor of water
and other products of combustion come in contact with the
heated limestone. Indeed, it is hardly possible by heat alone
in close vessels to expel the C03, since carbonate of lime is
fusible under those circumstances without decomposition.
Mortar acts as a cement by the slow formation of carbon-
ate of lime, which binds together the grains of sand that
# make up the greater part of the mixture. The smaller the
portion of lime used, and the sharper the silicious sand
employed, the more firm will be the cement at last ; but it
is then so much more difficult to work, that an excess of
Kme is usually employed. The presence of oxyd of iron
and manganese, of alumina, magnesia, silica, and other like
substances in a limestone, gives the lime prepared from it
the property of hardening under water, when it is called
hydravKc lime.
Lime is much used in improved agriculture, as a manure.
It acts to decompose vegetable matters, to neutralize acids,
dissolve silica, and retain carbonic acid. It is always present
naturally in every fertile soil, and is a constant ingredient in
the ashes of most plants.
536. Chlorid of Calcium, CaCl. — The solution of lime,
What heat is given out in this operation ? Where greatest ? How
soluble is the hydrate ? 535. How is common lime prepared ? Why is
vapor of water useful in the process ? How does mortar act as a cement?
What is hydraulic lime ? 536. What is the chlorid of calcium ?
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816 METALLIC ELEMENTS.
or of its carbonate, in hydrochloric acid to saturation, gives
us this chlorid. It is when fused a white crystalline solid,
with a great avidity for moisture, and for this reason it is
used in the desiccation of gases, &c. It is soluble in alcohol,
with which it forms a definite crystallizable compound. It
forms a powerful freezing mixture with ice, (124.)
The sulphurate and phosphurets of calcium have little in-
terest. The phosphuret being decomposed by water, is an
available source of the spontaneously inflammable phosphu-
retted hydrogen, (fig. 326.)
537. Sulphate of Lime — Gypsum — Selenite, CaO.SOr
—This salt, in the form of hydrate CaO.S08+2HO, is
abundant in nature, and is much used in agriculture as a
manure, being ground to powder; and, after expelling the
water by heat, as a material for stucco and plaster casts-
It is then commonly known as " plaster of Paris." The varie-
gated and fine white varieties are called alabaster. When
crystallized in transparent flexible plates, it is called selenite.
I These crystals are sometimes compound in
( such a manner as to present an arrow-head
form, like fig. 359. Such crystals are called
hemitropes. Anhydrous gypsum CaO.S03 also
is found native, and is known by the minera-
logical name of anhydrite.
Gypsum is frequently associated with rock-
salt It is soluble in about 500 parts of water,
and is present in most natural waters. By
a heat of 250° to 270° it loses its water of
composition: when the anhydrous powder is
moistened, the lost water is regained, and it
becomes solid ) but if heated, even to 330°, it
Fig. 359. no jonger regains its water of composition. It
fuses at a red heat to a crystalline anhydrous mass. This
power of resolidification, when mixed with water, gives
gypsum its value in copying works of art, and in forming
Btucco ornaments. By using solution of common alum in
place of water, gypsum becomes very hard, and is thus
treated for producing pavements.
For what is it used ? What is the phosphuret of calcium used for?
537. Give the common names of sulphate of lime. For what is it used f
Give its properties. What is fig. 359 ? How is gypsum hardened ? Om
what docs its use in stucco depend ? What is anhydrite ?
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CALCIUM. 817
538. Fluorid of Calcium, Fluor-spar, CaF. — This is a
rather abundant mineral, being found beautifully crystallized,
of various colors, in the cube and its modifications. It is the
principal source from which we obtain the fluohydric acid
(433) by decomposition with sulphuric acid. It often phos-
phoresces very beautifully with heat, emitting a green,
yellow, or purple light, at a temperature below redness.
539. Phosphates of Lime. — There are several phosphates
of lime corresponding to the several phosphoric acids, (355.)
The earth of bones is a tribasic phosphate of lime, and the
mineral known as apatite is also a phosphate of lime. The
phosphates of lime are insoluble in water, but dissolve in
dilute acids. All cereal grains, and many other vegetables,
contain phosphate of lime in their ashes, and this salt is
therefore an indispensable ingredient of all fertile soils, and
the form in which phosphorus is introduced into the animal
structure.
540. Carbonate of Lime — Marble — Calcareous Spar,
CaO.CCX,. — This is one of the most abundant minerals of
the earth, forming in limestone vast mountains and wide-
spread geological deposites. It oc-
curs most superbly crystallized in
rhombohedral forms, which consti-
tute brilliant ornaments in mineralo-
gical collections. The transparent
double refracting Iceland spar, (fig.
860,) and the dimorphous form,
arragonite, are examples of this salt. Fig. 360.
It is soluble in dilute acids, with escape of carbonio acid, and
is also decomposed by heat, leaving quicklime.
Water aided by carbonic acid, and perhaps by the organic
acids of the soil also, dissolves carbonate of lime, and again
deposits it in stalactites and stalagmites, on exposure to the
air. These phenomena are beautifully seen in Mammoth
Cave, Schoharie Cave, and many similar situations. The
stalactites depend from the roof, growing by the deposit of
freshly precipitated portions of carbonate of lime on their
538. What is fluor-spar ? How is it found ? For what used ? What
beautiful property has it ? 539. What phosphates of lime are known ?
In what do we find phosphate of lime ? How does phosphorus enter the
system ? 540. What is the formula of carbonate of lime ? What other
names has it ? What is formed from it ? What optical property has it?
How does water dissolve it ? What are stalactites and stalagmites ?
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818 METALLIC ELEMENTS.
surfaces, which are kept moist by the trickling of water con*
taining the salt in solution. The water which falls to the
floor from the point of each stalactite slowly builds up a coni-
cal mass called a stalagmite, and when these meet they form
a column. All these stages are well shown in fig. 361,
Fig. 361.
from Regnault. Before these fairy-like creations of nature's
architecture are darkened by torches, their beauty is en-
chanting.
541. Hypochlorite of Limey CaO.CIO, Bleaching-Pow-
der. — This valuable compound is formed^, when chlorine gas
is gradually admitted to hydrate of lime slightly moist and
kept cool. The chlorine is absorbed largely, and the bleach
ing-powder of the arts is formed. Bleaching- powders con-
tain a mixture of hypochlorite of lime, chlorid of calcium,
and hydrate of lime. It is a soft white powder, easily soluble
in about 10 parts of water, giving a highly alkaline solution,
which bleaches feebly. It is employed by dipping the
goods in the weak solution, and then in very dilute acid
water. The chlorine is thus evolved and does its work.
Several repetitions are needed to complete the process, and
the acid is washed out with care. This compound emits a
strong smell, which is similar to chlorine, but is due ta
Describe their formation as in fig. 361. What is bleaching-powder ?
How formed ? How employed ?
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MAGNESIUM. 319
hypochlorous acid ; it is very useful for disinfecting offen-
sive apartments, and its energy is increased by the addition
of a little acid water. The disinfecting liquid of Labarraque
is a compound of chlorine with soda, similar in composition
to solution of bleaching-powder.
The best bleaching-powders contain 39 parts of available
chlorine, and 2 parts, in combination, as chlorid of calcium.
If one equivalent of each ingredient were present they
would be in the proportion of 48 -57 chlorine and 51*43 parts
hydrate of lime. Ordinary bleaching-powders contain only
about 30 per cent, of chlorine. The mode of determining
the amount of chlorine present is called chlorimetry, and
is based on the quantity of sulphate of indigo which is
decolorized by a standard solution of chlorine. The salts
of lime are not precipitated by ammonia, but form an entirely
insoluble oxalate, with oxalic acid or oxalate of ammonia.
MAGNESIUM.
Equivalent, 12*2. Symbol, Mg.
642. Magnesium is obtained by decomposing the chlorid
of that metal heated to redness in a glass tube, by passing
over it the vapor of potassium or sodium. Chlorid of po-
tassium or sodium is formed, and the metallic magnesium
is separated by dissolving out the soluble chlorid.
It is a white metal, malleable and brilliant. It fuses
with a red heat, and if heated to redness in the air, burns
with a brilliant light, producing oxyd of magnesium. It
does not tarnish in dry air, and does not decompose water
even at 212°, but dissolves in acids with escape of hydrogen.
543. Oxyd of Magnesium, Calcined Magnesia, MgO.
This substance is left when the carbonate of magnesia is
heated to redness. It is a white, very light, earthy powder,
insoluble in water, but readily soluble in weak acids. It
occurs in nature crystallized in regular octahedrons, form-
ing the mineral periclase. It is much used in medicine as
a mild and efficient aperient. The hydrate of magnesia
What is Labarraque's liquor ? What is the composition of bleaching,
powder ? What is chlorimetry ? What precipitates the salts of lime ?
542. Give the equivalent and preparation of magnesium. What are its
properties ? 543. What is the oxyd of magnesium ? How is it used 1
How found in nature ?
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820 METALLIC ELEMENTS.
MgO.HO is formed wnen magnesia is precipitated from its
solutions by an alkali. Heat expels the equivalent of water,
leaving calcined magnesia. The hydrate is found beau-
tifully crystallized in thin pearly plates at Hoboken, New
Jersey.
644. Chlorid of Magnesium, MgCl. — This chlorid is best
prepared by neutralizing equal portions of chlorohydric acid,
on 3 with magnesia and the other with ammonia, mixing the
two portions and evaporating to dryness. The dry mass 5s
heated in a covered crucible as long as sal-ammoniac is given
off, when pure chlorid of magnesium is left. It is a very deli-
quescent salt, and supplies the means of procuring metallic
magnesium. When magnesia is dissolved in hydrochloric
acid, a hydrated chlorid of magnesium results. By heat the
water is expelled, carrying with it chlorohydric acid, and
leaving pure magnesia behind. The bittern of salt springs
is chlorid of magnesium ; it exists in sea-water, and is the
largest ingredient in the waters of the Dead Sea. The iodid
and bromid of magnesium are also soluble salts, but the
fluorid is insoluble.
545. Sulphate of Magnesia, Epsom Salts, MgO.S08-|-
7HO. — This well-known salt is easily formed by dissolving
magnesia, or its carbonate, in sulphuric acid. It is also
found native at Corydon, Illinois. In the waters of Epsom
Spa, in England, and in numerous mineral waters, it is a
large constituent. It is made on a large scale by dissolving
serpentine rock in strong sulphuric acid. It is very soluble,
and, like all the soluble salts of magnesia, has a peculiar
bitter taste.
546. The carbonate of magnesia, magnesite, MgO.COa,
is found native in magnesian rocks, and is formed artificially
by decomposing any of the soluble salts of magnesia by an
alkaline carbonate, giving the magnesia alba of pharmacy.
It is insoluble in water; but a solution of carbonic acid
dissolves it, and forms the celebrated Murray* s solution of
magnesia. It is decomposed by contact of air, carbonic acid
escapes, and carbonate of magnesia is thrown down. The
double carbonate of magnesia and lime is found as an ex-
What is calcined magnesia? 544. How is the chlorid of magnesium
prepared? Describe it. When magnesia is dissolved in chlorohydric
acid, what happens ? 545. What is the composition of sulphate of mag-
nesia? How is it made in the large way? In what waters is it found?
146. What is carbonate of magnesia ? What is Murray's solution ?
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ALUMINUM. 321
tensive rock formation, called dolomite, and when crystal
iized, pearl spar.
Phosphate of soda with ammonia throws down a crys
talline insoluble salt from magnesian solutions, which is
the double phosphate of magnesia and ammonia. This is
the most ready mode of testing for the presence of magnesia.
547. Magnesia occurs abundantly in nature as a con-
stituent of many minerals, as well as in the form of hydrate
and carbonate. The silicates of magnesia form a very im*
portant class of minerals, of which talc, soap-stone, pyroxene,
hornblende, serpentine, &c., are examples. Magnesia is also
found in the ashes of most plants, in union with phosphoric
acid.
CLASS III.— METALS OF THE EARTHS.
ALUMINUM. Al. = 1 3 -69.
548. Aluminum is best obtained, like magnesium, by the
action of sodium or potassium on its chlorid. It. is a gray
powder, not easily melted, has a metallic lustre, and burns,
when heated in the air, with a bright light, forming alumina.
549. Alumina; Sesquioxyd of Aluminum ; Corundum^
Ala08. — Pure alumina is found crystallized in those precious
gems, the oriental ruby and sapphire, which are next in
hardness and value to the diamond. Emery (cornudum) is
also nearly pure alumina. Alumina is an abundant ingre-
dient in many other minerals, and forms a large part of many
slaty rocks, from whose decomposition clays are produced.
Pure alumina is a fine white powder, not rough and gritty
like silica. Its density is 4*154. It is infusible except
under the oxyhydrogen blowpipe. After ignition it is al-
most or entirely insoluble.
Hydrate of alumina AlflOa+3HO exists in the minerals
diaspore and gibbsite. Alumina is precipitated as a hydrate
from solution, by either potash, soda, or ammonia, and their
carbonates; an excess of the first two will redissolve the
precipitate. The hydrate is very bulky, and shrinks very
What test have we for magnesia ? 547. How does magnesia occur in
feature ? Mention some of its silicates. 548. How is aluminum obtained?
What are its properties and density ? 549. What is the formula of alu-
mina ? In what is it found pure ? How aro the hydrous and anhydroua
alumina distinguished ? What precipitates and what redisaolyea it ?
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822 METALLIC ELEMENTS.
much on drying. Hydrosulphuret of ammonium throws
down alumina. The anhydrous alumina is almost insoluble
in acids, while the hydrate is readily dissolved, forming sails
of a peculiar astringent taste, familiarly known in common
alum.
The ehlorid of aluminum has no particular interest except
as a means of procuring the metal.
Aluminate of potassa KO. AlsOs is formed when a solution
of alumina in potassa is gently evaporated : it appears in
crystalline grains. IJaryta and magnesia afford similar
examples. Spinel, a mineral species, is an aluminate of
magnesia MgO.Als03. These are instances of the double
function which alumina possesses of acting the part both of
acid and base, (474, 3.)
550. Sulphate of Alumina, Ala08.3S08+18HO.— This
salt is prepared by saturating dilute sulphuric acid with
alumina : it has a sweetish astringent taste, is soluble in 2
parts of water, and crystallizes in thin plates.
Hums. — Sulphate of alumina forms, with potash, soda,
and ammonia, double salts of much interest, called alums.
They are all soluble salts, with a sweetish astringent taste,
and crystallize in the regular system, or first class, (44,)
usually as modified octahedrons, which have uniformly 24
equivalents of water of crystallization. Common potash-
alum has the formula AlaOa.3S08+KO.SOg+24HO, (256;)
it dissolves in 18 parts of cold water, and the solution has
an acid reaction. The water of crystallization of the alums
is expelled by heat : the salt first suffers watery
fusion, and then swells up into a light porous
mass, many times the volume of the salt em-
ployed, and protruding beyond the vessel
employed, as in fig. 362. This is called burnt-
alum. All the basic sesquioxyds isomorphous
with alumina may replace it in the constitu-
tion of an alum.
Alum and acetate of alumina are largely
1 employed in the arts of dyeing and tanning.
Fig. 362. Alumina combines with coloring matters, and
seems to form a bond of union between the fibre of the cloth
What salts does it form? What is aluminate of potassa? What if
spinel ? Give the formula of alum. 550. What is burnt alum ? What
is the use of alums ?
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ALUMINUM. 823
and the color. In this it is said to act the part of a mor-
dant. When alum is added to the solution of a coloring
^matter, and the alumina is then precipitated with an alkali,
all the coloring matter is thrown down with it, and forma
what is called lake. The common lake used in water-color-
ing is derived from madder treated in this way. Carmine
is a lake made from cochineal.
551. Silicates of Alumina. — This is the most extensive
and important class of the aluminous salts, and comprises a
great number of interesting minerals. Feldspar, A1303#
SSiOg-f-KO.SiOg, which is one of the chief components of
granite and granitic rocks, is of this class, and has the com
position of an anhydrous alum, the sulphuric acid being
replaced by the silicic. Albite is a salt having soda in place
of the potash in feldspar, while spodumene and petalite are
similar compounds, with a portion of the soda replaced by
Uthia. Kyanite and andalusite are simple basic silicates
of alumina. Many other similarly constituted compounds
are found among minerals, some of which are hydrous and
others anhydrous, and varied by frequent substitution of
peroxyd of iron, manganese, or other isomorphous bases,
for the alumina.
Plants do not take up alumina, and it is not yet proved
that their ashes ever contain it. Its value in the soil seems
to be in retaining moisture, ammonia, and carbonic acid, and
in giving firmness to the other incoherent components of the
soil. The decomposition of these silicates gives origin to
olay, whose peculiar qualities derived from the alumina fit
it for the purpose of the potter.
This is the place to say a few words upon the two import-
ant arts of glass-blowing and pottery.
Manufacture of Glass.
552. Silicates of Soda. — Both soda and potash unite by
fusion with silicic acid to form silicates of variable compo-
sition. If 3 parts of the alkali are used to 1 of the silica,
tho glass is soluble in water, but whatever may bo the pro-
What is a mordant ? What a lake ? 551. What is the most important
class of alumina compounds ? What is the formula of feldspar ? What
silicates are named? What is the function of alumina in soils? What
aqe clays ? 552. How do the alkalies unite with silica. What is the cha*
racier of the compounds so obtained ?
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824 METALLIC ELEMENTS.
portions used, tbe resulting silicate is always an uti crystal-
line, homogeneous, transparent mass. The "soluble glass"
formed by fusing together 8 parts of carbonate of soda (or
10 of carbonate of potash) with 15 parts of pure sand and
1 of charcoal, is insoluble in cold, but dissolves in 4 or 5
parts of hot water, forming a sort of Tarnish, which may be
applied to wood or manufactured stuffs, which are to a good
degree protected from it by the action of fire.
553. Glass is a variable compound of the silicates of!
potash, soda, lime, and alumina, with oxyds of lead and
iron, fused together by a very high and long-continued heat,
in proportions suited to the object for which the glass is to
be used. The relation between the oxygen in the base and
that in the silica determines the degree of fusibility of the
glass : thus, the greater the proportion of silica the less the
fusibility of glass. The principal varieties of glass are
these, viz :
Window glass, a silicate of soda and lime, which re-
quires an intense heat for its fusion, and forms a very
hard and brilliant glass. Plate glass, such as is used for
mirrors, crown glass employed for glazing, and the beauti-
ful Bohemian glass, are all silicates of potash and lime.
Crystal glass is formed by fusing together 120 parts of
fine sand, 40 of purified potash, 36 of litharge or minium,
(oxyd of lead,) and 12 of nitre. This forms a very fusible
glass easily worked, and so soft as to be cut and polished
with comparative ease. The oxyd of lead greatly increases
its brilliancy.
Green bottle-glass is usually a silicate of lime and alumina!
with oxyds of iron and manganese, and potash or soda. It
is formed of the cheapest refuse of the soap-boiler's waste,
and lime which has been used to make caustic potash or
soda.
554. The processes of the glass-house are all exceedingly
interesting and instructive — the tools few and simple — the
results dependent on the adroit manipulations of the work-
man. The materials are fused in clay pots, of which seve-
ral are heated in one circular reverberatory furnace, their
What is soluble glass ? 553. What is glass ? What determines th#
fusibility of glass ? What sorts are named ? What is the composition
of window and plate ? What of crystal ? What of green bottle-glass?
654. How are the materials fused ?
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ALUMINUM.
325
mouths outward. Fig. 363 shows a section
of one of them. After two days and nights,
tiie metal, or fused glass, is brought to a
homogeneous condition and the consistence of
honey. The chief instrument of the glass-
blower is his punta rod, which is simply an
iron tube a b, fig 364, open at both ends and
covered by a wooden collar c d to protect the Fi 363
hands from the heat. This rod is thrust into
the pot of molten glass while it is turned in the hand, a
portion of the fluid j g d *
glass adheres to it, the •■■ ^S5a™i^Hi*™=^^^=^
rod is withdrawn, and Fi* 364'
if enough has not adhered to meet the wants of the work-
man, he takes up a second portion. This he first fashions
into a cylindrical form upon a
slab of iron, rolling the rod over
and over in his hand, (fig. 365.)
Suppose it is required to make
a glass tube, such as is so much
used in the laboratory. He ap- Fig' m
plies his mouth to the end of the punta-rod and blows.
The cylinder of glass is inflated, find assumes M^%
a pear shape, as in fig. 366. An assistant now ' ^vJP.
applies his tube, containing also a small FiS«366-
portion of hot glass, to the opposite extremity of the first
mass, (fig. 367,) and drawing against the other, the ellipti-
Fig. 367. Fig. 368.
oal mass is elongated and assumes the form seen in fig. 368.
The two workmen now walk rapidly away from each other in
opposite directions, drawing their tubes in the same line,
giving the ductile glass the form of a tube, as seen in fig.
369. A few inches from each punta-tube the glass beconfes
Fig. 3G0.
of a uniform size, the small cavity originally blown in the
What are the instruments used? How is a glass tube formed?
Irate the process from figs. 363-369. What is pressed glass ?
Ulus.
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826 METALLIC ELEMENTS.
mass (fig. 366) is elongated to a smooth cylindrical bore, ainl
however small the glass tube may be drawn out, this bort
always remains circular and entire through its whole length,
To fashion a bottle, the operation is commenced in the same
manner, but the adroitness of the workman enables him to
elongate it by centrifugal force, wheeling the molten mass
over his head while he inflates it; a«d the bottom is drawn in
by revolving the rod rapidly on a crotch while he applies the
surface of an iron instrument to the revolving flexible glass
to fashion it at his will. Most of the cheap glass vessels now
manufactured are formed by blowing the glass in a metallic
mould opening in two parts. This is called pressed glass.
In the laboratory a flat lamp, like fig. 370, fed with tallow,
is employed to fashion tabes
into the various forms re-
quired for the construction
of the apparatus. The flame
is driven by a bellows under
the table worked by the foot
F 370 With a little practice, the
lff* ' operator soon acquires suf-
ficient skill to make from plain tubes such forms of glass
apparatus as are figured|in this work.
All glass must be carefully annealed after it is made, by
slow cooling, or it will break in pieces with the least scratch
or jar. Slow cooling of heated glass for many hours, ox
even days, is required for heavy articles. Prince Rupert's
y00" drops (fig. 371) are little tears of glass dropped
yf into water when fused. The outer surface becom-
il ing solid while the inner parts are still flexible,
I m there comes to be an enormous strain on the ex*
^Nr terior, due to the contraction at the centre. If the
Fig. 371. Y\tt\Q end of this tear is broken, the whole sud-
denly and with an explosion flies into dust. Unannealed
glass is to a certain degree under the same conditions of
unequal tension. Hence the necessity of annealing or slow
cooling to give time for the* particles to rearrange them-
selves without strain. Glass is colored red by the oxyds of
copper and gold, blue by oxyds of cobalt, white by tin,
How is glass worked in the laboratory ? What is annealing? How is
this illustrated by Prince Rupert's drops? Explain the illustration. How
Is glass colored ?
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ALUMINUM. 827
arsenic and antimony, yellow by uranium, purple and violet
by manganese, and green by chromium, iron, nickel, &c.
By the skilful use of these oxyds, with a heavy and highly
refracting glass, the various gems are very beautifully imi-
tated. Such imitations are called pastes.
Pottery.
555. One of the oldest of human inventions is the
fashioning of vessels of use and ornament out of clay. The
bricks of Babylon and Nineveh, covered with arrow-head
inscriptions, are among the most ancient memorials of
history.
The decomposition of feldspar and other aluminous mine-
rals and rocks gives origin to the clays which are so import-
ant in the art of pottery. Decomposed feldspar forms
porcelain clay, commonly called kaolin. The undecom-
posed mineral is often ground up to mix with the materials
for porcelain. The difference between porcelain and earthen-
ware consists in the partial fusion of the materials of tho
former by the heat of the furnace, which gives it the semi-
transparency and great beauty for which it is so highly
prized. Common earthenware is often glazed with oxyd
of lead, an unsafe mode for culinary vessels : common salt
(508) is also used, being raised in vapor by the heat of the
kiln. The soda unites with silica, while the chlorine escapes
as chlorid of iron. The glaze in porcelain is formed of a
more fusible mixture of the same materials, put over the
articles as a wash, after they have been once through the
furnace, (in which state they are called biscuit ware;) they
are then baked again at a' heat which fuses the glaze, but
which does not soften the body of the ware. All porcelain is
twice fired and sometimes thrice. If painted, the design is
laid upon the surface in colors formed from metallic oxyds,
which develop their appropriate tints only after fusion with
the ingredients of the glaze. Metallic gold is put on in the
form of an oxyd, and the steel lustre is produced by metal-
lic platinum. This beautiful art is carried to a wonderful
How made refractive ? 555. What is one of the most ancient arts?
Whence is potter's clay derived ? What is kaolin ? What is the
difference between porcelain and earthenware ? How is pottery glazed ?
How porcelain ? How painted ?
Digitized
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828 METALLIC ELEMENTS.
perfection in the royal establishments of France and Prus-
sia, where the first talent is employed in modelling and paint-
ing. Any further detail of these interesting branches of
applied chemistry would be out of place here, and the stu-
dent is referred to larger works for a fuller description.
556. There are six other metals belonging to this class,
which are so rare and comparatively unimportant that we
pass them with the most cursory enumeration : Glucinum
is the base of a sesquioxyd GflOs, (glucina,) which is the
characteristic earth of the emerald, beryl, and chrysoberyl,
It is very like alumina, and is named in allusion to the
sweet taste of its salts. Yttrium is the metal of the earth
yttria YO, found in the minerals yttrocerite, &c. Zir-
conium is found as a sesquioxyd of zirconia Zra03 in zircon.
Thoria was found by Berzelius in the rarest of all minerals;
the thorite, of Sweden. Thorium has the highest specific
gravity (9) of any earth. Cerium and lantanium are in-
variably associated, and with them another rare metal, didy-
mium. The minerals cerite, aUanite, and monazite contain
them.
CLASS IV. HEAVY METALS, WHOSE OXYDS FORM
POWERFUL BASES.
MANGANESE.
Equivalent, 27*6. Symbol, Mn. Density, 8.
557. Manganese is never found as a metal in nature, but
may be produced from its black oxyd by a high heat with
charcoal. Metallic manganese is a gray, brittle metal, not
magnetic, and resembles some varieties of cast-iron. It dis-
solves rapidly in sulphuric acid with escape of hydrogen.
Manganese, in the form of the black oxyd, is an important
and pretty common metal. Its great use is for producing
chlorine (282) and in the manufacture of glass, where it
acts by its oxygen to decolorize the compound.
558. We enumerate five compounds of manganese, vis.
protoxyd MnO ; sesquioxyd (or braunite) Mn90H ; peroxyd,
or deutoxyd, (pyrolusite,) MnOfl; manganic acid MnOt;
hypcrmaDganic acid MnaOr
656. Enumerate the other earthy metals named in this section. 557.
What are the equivalent and properties of manganese ? What form of it it
most common ? For what is it used ? 558. How many and what oxyd!
if manganese are named?
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MANGANESE. 829
The protoxyd is a green-colored powder, formed from
heating the carbonate of manganese in an atmosphere of
hydrogen. It is a powerful base, attracts oxygen from the
air, and is the base of the beautiful rose-colored salts of
manganese.
The sesquioxyd or braunite occurs crystallized in octahe-
drons and forms belonging to the dimetric system.
The hydrated sesquioxyd Mna08+H0 (manganite) is a
finely crystallized mineral, in long black prisms, found in
superb specimens at Ilfeld, in the Hartz. In powder the
sesquioxyd is brown ; it is decomposed by chlorohydric acid
with the evolution of chlorine, but sulphuric acid combines
with it to form a sesquisulphate, which yields a purple
double salt with sulphate of potash, (manganese alum,) iso-
morphous with the corresponding salt of alumina.
559. The peroocyd Mn03 is the most common and most
valuable ore of manganese. From it we* obtain oxygen, and,
by the decomposition of chlorohydric acid, chlorine. It is
found abundantly at Bennington, Vermont, and other places
in this country. When crystallized it is called pyrolusite.
Beautiful specimens of this mineral have been observed at
Salisbury and Kent, Connecticut, among the iron ores.
560. Manganic acid is known only in combination, espe-
cially as manganate of potash. This is best formed by mix-
ing equal parts of finely powdered black oxyd of manganese
and chlorate of potash with rather more than one part of
hydrate of potash dissolved in a very little water. This
mixture, when evaporated, is heated to a point short of red-
ness, and a dark green mass is formed which contains man-
ganate of potash. In this case the manganese obtains oxygen
from the chlorate of potash, and the manganic acid thus
formed combines with potash, giving a salt in green crystals.
This salt, dissolved in water, gives a brilliant emerald-green
solution, which almost immediately changes color, being in
quick succession green, blue, purple, and finally crimson-
red, and has thence been called chameleon mineral. This
last color is due to the presence of permanganic acid, which,
however, cannot be separated from its combinations, but
Which is the base of the rose-colored salts ? What is the sesquioxyd ?
Give the formula of the hydrated sesquioxyd? What is said of the sul-
phate of the sesquioxyd? 559. Which is the most common ore of man-
ganese ? Where and how is it found ? 560. Describe manganic acid and
the salt it forms with potash. What is the changeable compound called?
Digitized by VjOOQ IC
S30 METALLIC ELEMENTS.
forms a salt with potash in beautiful purple crystals. The
compounds of permanganic acid are more stable than the
manganates. The salts of these acids are respectively iso-
morphous with sulphates and perchlorates SO, and ClsOr
561. The chloruU of manganese MnCl and Mn?Cl8 cor-
respond to the protoxyd and sesquioxyd. The adorid is
formed abundantly in acting on black oxyd of manganese
(282) with hydrochloric acid. The mixed solution of chlo-
rids of iron and manganese is evaporated to dryness, and
then heated to dull redness. The chlorid of manganese is
then dissolved out from the dry mass, leaving the insoluble
protoxyd of iron behind. It has a beautiful pink tint, and
deposits tabular rose-colored crystals on evaporation. It is
soluble in alcohol, and fusible by heat.
562. The salts of manganese are numerous, and in a
chemical view quite important. Sulphate of manganese
MnO.SOg-f-THO is a very beautiful rose-colored salt, iso-
morphous with sulphate of magnesia. It is used to give
a fine brown dye to cloth, being decomposed by a solution
of bleaching-powder, which forms the brown peroxyd in the
fibre of the stuffs. It is also used in medicine.
Potassa and soda throw down the oxyd of manganese as s
white powder, which immediately turns brown from the forma-
tion of a higher oxyd. The carbonates of the alkalies throw
down carbonate of manganese from their soluble salts. Any
compound of manganese fused upon a slip of platina with
carbonate of soda, gives a powerfully characteristic green salt,
the permanganate of soda.
IRON.
Equivalent, 28. Symbol, Fe. Density, 7*8.
563. Iron is found malleable, and alloyed with nickel, in
large masses of meteoric origin. One of these, discovered in
Texas, weighs 1635 pounds, and is now in Yale College
cabinet. It is not certain that malleable iron of terrestrial
origin has yet been discovered in nature. Iron is the most
abundant and most useful metal known to man. Its ores
What is said of the salts of manganic and permanganic acid? 561.
Describe the chlorids of manganese ? 562. What is said in general of
the salts of manganese? What tests are named for manganese and it*
lalts? 563. What is the equivalent of iron? How is malleable iron
found? What is said of its abundance and value?
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IRON.
331
arc found everywhere, and often in immediate connection
with the coal and limestone necessary to reduce them to the
metallic state. There is no soil, and scarcely any mineral,
which does not contain some proportion of the oxyd of iron.
We know iron as malleable iron, steel, and cast iron.
564. To obtain pure iron is not easy, and the best iron of
commerce is always contaminated with carbon and silicon.
Small quantities of iron are prepared absolutely pure, in the
laboratory, by reducing the pure oxyd of iron in a bulb of hard
Fig. 372.
glass a b (fig. 372) by a current of dry hydrogen. The bulb
A is heated by the flame of a spirit-lamp. This apparatus
serves for numerous reductions of metallic oxyds, as, for
example, the oxyds of cobalt, nickel, zinc, <fec. The bulbed
tube a b is drawn down at c (fig. 373) to a narrow neck,
so that while the tube is yet a
full of hydrogen it may be seal-
ed by the blowpipe both at c & &~
and b: otherwise the pulverulent Fig- 373.
metallic iron, from its strong affinity for oxygen, will take
fire on contact of air, and be carried back again to its original
condition of oxyd. If this operation is conducted in a por-
celain tube at a high heat, the iron formed assumes a metallic
lustre, and does not oxydize ; and if protochlorid of iron is
used in place of the oxyd, the metal rises in vapor, lining
the tube with a brilliant crystalline crust.
665. When quite pure, it is nearly white, quite soft, 'per
fcctly malleable, and the nltst tenacious of all metals, (471.)
Its density is 7 8, which may be a little increased by ham-
564. How is pure iron obtained ? Describe fig. 372. What happens
if the iron so obtained is exposed to air ? How is it obtained more dense]
664. What are its properties ?
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832 METALLIC ELEMENTS
mering. It crystallizes in forms of the first class, a» ig
beautifully shown in the crystalline structure of the meteoric
iron, and sometimes in the crust produced
in the reduction of the protochlorid. It
fuses with extreme difficulty, first becom-
ing soft or pasty, in which state it is
welded. When intensely heated in air
or oxygen gas it combines with oxygen,
burning with brilliant light and numerous
scintillations, and is converted into oxyd
of iron, (fig. 374.) Iron also attracts
Fig. 374. oxygen from the air at common tempera-
tures, forming rust. This does not happen in dry air, but
the presence of moisture, and particularly of a little acid
vapor, very much promotes its formation. Iron decomposes
water very rapidly at a red-heat, hydrogen being evolved.
Its magnetic relations have already been fully explained.
Cobalt and nickel are the ouly other magnetic metals.
566. The oxyds of iron aro three, viz : 1. Protoxyd,
FeO; 2. Sesquioxyd, commonly called peroxyd, Fe808;
3. Ferric acid, Fe08. The magnetic oxyd Fe304 is regarded
as a compound of protoxyd and sesquioxyd FeO.Fe^Oj, in
which the sesquioxyd plays the part of a base, (475.)
1. The protoxyd of iron FeO is a powerful base which
is unknown in nature except in combination. It saturates
acids completely and is isomorphous with a large class of
bodies, of which zinc and magnesia are examples, (263.)
This oxyd is thrown down from its solutions by potash, as
a whitish bulky hydrate, that soon gains another portion
of oxygen from the air, becoming brown, and finally red.
Its salts, when soluble, have a styptic taste like ink, and a
greenish color, of which the most familiar example is green
vitriol y or sulphate of protoxyd of iron.
2. The peroxyd of iron Fea08 is found native in the
beautiful specular iron of Elba, and also in the red and
brown hematites. Limonile 2(Fea08)+3HO is a hydrous
sesquioxyd. It is slightly acted on by the magnet, and
after ignition is almost insolublefin strong acids. It is iso-
morphous with alumina, and is generally associated with it
in soils and many minerals. It is often of a brilliant red,
What is welding ? 566. What oxyds are named ? Give their formulas.
Describe the protoxyd and its salts. How is the peroxyd known ?
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ikon. 833
and, as ochre of various tints, is much used as a pigment
Ammonia, potassa, or soda precipitates it from its solutions
as a bulky red hydrate, which, in its moist condition, is
esteemed an antidote to poisoning by arsenic. Colcothar,
or rouge, is this oxyd prepared by calcining the sulphate : it
is much used in polishing metals.
Magnetic oxyd of iron Fe804 is familiarly known in the
common magnetic iron ore and native lode-stone. It crys-
tallizes in octahedrons. It forms no salts, and, as has al-
ready been remarked, is regarded as a salt of FeO+FeaOt.
The finery cinders or scales thrown off under the smith's
hammer are this oxyd.
3. Ferric Acid, Fe08. — This compound, discovered by M.
Fremy, corresponds to manganic acid. Ferrate of potash is
formed when one part of peroxyd of iron and four parts of
nitre are heated to full redness in a covered crucible for an
hour. The ferrate of potash is dissolved out of the porous
mass by ice-cold water. The solution has a deep amethyst-
ine color, and is easily decomposed by heat. A soluble
salt of baryta precipitates ferric acid as a beautiful red fer-
rate of baryta, which is permanent.
567. The chlorids of iron FeCl and FeaCl8 correspond to
the protoxyd and sesquioxyd of the same base. The per-
chlorid is often used in medicine, and may be formed by
saturating hydrochloric acid with freshly prepared peroxyd
of iron. The protiodid of iron is also a valuable medicine.
The sulphurets of iron are found in nature, and are known
under the mineralogical names of pyrites and marcasite
FeSs, and magnetic pyrites Fe.Ss. The protosulphuret FeS
is easily formed artificially, t>y fusing sulphur with iron
filings: they ignite with a vivid combustion, and proto-
sulphuret of iron is formed, which is much used in pre-
paring sulphuretted hydrogen. Yellow iron pyrites and
white iron pyrites (marcasite) are dimorphous forms of the
bisulphuret FeSa : the first is one of the most common of
crystallized minerals.
568: Of the salts of iron, green vitriol, or copperas, a pro-
What is colcothar ? Giro the formula of the black oxyd. How is it found
in nature ? What is ferric acid ? 567. What chlorids of iron are named t
What oxyds do they correspond to ? What are the sulphurets of iron ?
For what is the protosulphuret used ? What is the name of the ordinary
•ulphuret? What two forms of it are found in nature?
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834 METALLIC ELEMENTS.
tosulphate FeO.S08+7HO, is the most important. It i*
made in immense quantities, as at Stafford, Vt , from the
fermentation of iron pyrites, which furnishes both the acid
and the base. This salt crystallizes beautifully, and is
much used as the basis of all black dyes and of ink, and in
the manufacture of prussian blue. Persulphate of iron is a
sulphate of the peroxyd FeaO,+3SO,. Carbonate of iron
occurs in nature as spathic iron ore, which is isomorphous
with carbonate of lime. A variety of steel is made directly
from this ore without cementation, (570.) It is formed
artificially by precipitating a solution of protosulphate by
an alkaline carbonate. It is used in medicine.
Water containing carbonic acid dissolves protozyd of iron
and acquires the well-known flavor of chalybeate waters :
exposure to air permits the escape of the carbonic acid,
when the iron falls as red peroxyd.
Phosphate of iron FeO.P05+8HO is formed as a green-
ish-white gelatinous precipitate when solution of tribasio
phosphate of soda is added to solution of protosulphate of
iron. It is an article of the materia medica. Yivianite
is a mineral having the same formula, found both massive
and crystallized, of a beautiful indigo-blue color.
The cyanogen compounds of iron will be described in the
organic chemistry.
The presence of a salt of iron is easily detected by the
fine blue ('prussian blue) formed on adding prussiate of
potash to the solution : an infusion of galls gives a black
color (ink) to solutions of iron salts.
569. The chief ores of iron are, 1. The specular iron or
peroxyd, including red and brown hematite; 2. Limonite, or
hydrous peroxyd, from which the best iron is made — (bog
iron also comes under this head ;) 3. Clay iron-stone, which
is an impure carbonate of iron, or carbonate of iron with
carbonate of lime and magnesia — this is the nodular ore and
band ore of the coal formations ; 4. Black or magnetic oxyd
of iron, which is the ore of the iron mountains of Missouri
and of Sweden.
The reduction of the ores of iron to the metallic state it
asually performed in large furnaces called high or blast fur-
568. Which of the salts of iron is of great importance ? How and
where is it made in this country ? What is the carbonate and for what
used ? What of the phosphate ? What tests are named for iron ? 569. What
ores of iron are onumerated ? How is the reduction of iron effected ?
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IRON.
335
naces. These are built of stone,
in a conical form, 30 to 50 feet
high, and lined internally with
the most refractory fire-bricks.
The furnace is divided into the
throat, the fire-room b, the
boshes e, (that portion sloping
inward,) the crucible ty and
the hearth A. The blast of
air — supplied from very large
blowing cylinders — is intro-
duced by two or three tuyere^
pipes a a, near the bottom. In
the most improved furnaces, the
air-blast is heated by causing a^_
it to pass through a series of j ,
pipes in the upper portion of the Jil
furnace, so as to have a temper- Fig. 375.
ature of 500° or more when it enters the furnace. When
the furnace is brought into action, it is first heated with
.coal only, for about 24 hours, to raise it to the proper tem-
perature ; and then is charged alternately with proper pro-
portions of coal, roasted ore, and lime for flux, until it is
quite full. When once brought into action, the blast is
kept up for months or even years, until the furnace requires
repairing. The ore is reduced on the boshes, and in the
upper part of the crucible, where the oxyd of carbon is found
almost pure in presence of an excess of white-hot carbon and
ore previously dried and in part reduced in the higher parts
of the furnace. The melted metal collects on the hearth,
where it rests, covered by the molten flux, which is a glass,
formed by the fusion of the lime used, with the earthy parts
of the ore. From time to time, the iron is drawn off by an
opening level with the hearth, previously stopped with clay,
and run into rude open moulds in sand. This is cast iron,
and is of various qualities, according to the various charac-
ter of the ore and the working of the furnace. If malle-
able bar iron is wanted, the cast iron is again melted, in
what is called the puddling furnace, where it is stirred
Describe the high furnace. What is the hot blast? What is the ope-
ration of the furnace ? What is cast iron ? How is malleable iron mads
from cast iron ?
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S36 METALLIC ELEMENTS.
about by an iron rod, in contact with oxyd of iron, and a
current of heated carbonic oxyd from burning wood or coal.
It gradually becomes stiff and pasty from the burning out
of the carbon, and from some molecular change not well
understood. This pasty condition increases until the iron
is finally raised in a rude ball and placed under the blows
of a huge tilt-hammer, when the scoria is pressed out and
the particles made to cohere. It grows tenacious by a repe-
tition of this process, being cut up and piled or faggoted and
reheated several times, until it is finally rolled in the roll-
ing-mill into tough and fibrous metal.
570. Steel is formed from refined iron by heating it for
days in succession in contact with charcoal in close vessels,
(called cementation.) It gains from ono to two per cent
of carbon, becomes fusible, and can be tempered according
to the use for which it is designed.
The Catalan forge is a furnace formed like a smith's forge
on a large scale, and in which the circumstances of the high
and puddling furnace are combined, so that malleable iron
is produced from the ore — the cast iron being brought to
the ductile state in the same fire where it is reduced from
the ore — charcoal is the fuel of the Catalan forge. The
best iron is always produced when charcoal is the fuel, being
free from sulphur and phosphorus, the two worst enemiei
of good iron.
CHROMIUM.
Equivalent, 26*4. Symbol, Cr. Density, 6.
571. Chromium in combination with iron is rather an
abundant substance, particularly in this country, being found
as chromic iron at Barehills, near Baltimore ; Lancaster Co.,
Pa., and in several other places. The beautiful red chro-
mate of lead is also a natural product in Siberia. The
metal, from its great affinity for oxygen, is very difficult to
procure. It is a hard, almost infusible substance, resem-
bling cast iron, nearly insoluble in acids, and does not
decompose water. It may be oxydized by fusion with nitre,
but does not change in the air.
570. What is steel? What is the Catalan forge? What fuel makes
the best iron? 571. What are the symbol and properties of chromium?
How distributed in nature ?
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CHROMIUM. 337
" 572. The oxyds of chromium are exactly the same as
those of manganese. Chromium bears the strongest analogy
in its chemical character to manganese and iron. The pa-
rallelism of constitution in the oxyds of these three metals
is shown in the following tabular arrangement : —
Acids.
Protoxyd. Sesquioxyd. Black oxyd. Peroxyd. , * ■■■■^
Manganese forms.. MnO ... Mn»0, ... Mn,0« ... MnOa MnO, Mn«0«
Iron forms. FeO ... Fe,0, ... Fe,04 ... FeO,
Chromium forms...CrO ... Cr,0, ... Cr,0« ... CrO» CrO, Cr»Of
The protoxyd of chromium is a strong base, acting in
combination like the protoxyd of iron, with which it is iso-
morphous.
573. Sesquioxyd of chromium Cra03 may be obtained
in little rhombohedral crystals by passing the vapor of chlo-
rochromic acid through a heated tube, 2CrOaCl = CraOs-f-
2C1-J-0. The crystals are deposited on the walls of tho
tube in a brilliant deep-green crust. They are as hard as
ruby. Their density is 5*21.
The hydrated sesquioxyd of chromium Cra03+HO is
easily prepared by treating a boiling and rather dilute solu-
tion of bichromate of potash with an excess of chlorohydric
acid, and then wi£h successive portions of alcohol or sugar
until it assumes a fine emerald tint. Ammonia throws down
a bulky, pale-green precipitate, soluble in acids and shrink-
ing very much in drying — this is the hydrate. On ignition
it undergoes vivid incandescence and becomes deep green.
The sesquioxyd of chromium is a feeble base like those of
iron and alumina, and may replace them in combination, as
in the formation of chrome alum with sulphate of potash.
Sesquioxyd of chromium forms an alum also with the sul-
phates of soda and ammonia. All the salts of this oxyd
are either emerald green or bluish purple. It imparts a
rich tint of greeu to glass and porcelain, and is the cause
of the color of the emerald. Chrome iron is composed of
this oxyd and protoxyd of iron FeO.CraOa, isomorphous with
magnetic iron FeO.Fefl03, and with spinel MgO.Ala08. The
chrome iron of Pennsylvania contains a little nickel.
574. Chromic acid Cr08 is readily formed by treating
572. What strong analogies has it ? Give the parallel oxyds of Mn, Fe,
and Cr. 573. How is sesquioxyd of Cr obtained ? How is its hydrate ?
What are its properties ? What salts does it form ? What is chrome iron ?
574. How is chromic acid formed ?
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838 METALLIC ELEMENTS.
a cold and concentrated solution of bichromate of potash
with one and a half parts of sulphuric acid. The mixture,
when cold, deposits brilliant ruby-red prisms of chromic
acid. The sulphate of potash in solution above, may be
turned off, and the chromic acid dried on a porous brick,
being carefully covered with a glass to prevent access of
organic matters, which at once decompose it. If a little of
this acid be thrown into alcohol or ether, the violence of the
action is such as to set fire to the mixture. Chromic acid
forms numerous salts, which are highly colored.
The protochlorid of chromium CrCl is obtained as a
white and very soluble substance by the action of dry hy-
drogen gas on the sesquichlorid. The tesquichloritl CraCl9
is prepared by passing chlorine gas over an ignited mixture
of the sesquioxyd and charcoal. It forms a crystalline
sublimate of a peach-blossom color, which is insoluble in
water. The sesquioxyd dissolves in chlorohydric acid,
but the hydrated chlorid thus obtained is decomposed by
heat.
Ghlorochromic acid Cr03Cl is a deep-red volatile liquid,
much resembling bromine in its appearance. It is formed
when 10 parts of common salt and 17 of bichromate of
potash are intimately mixed, and heated in a retort with
30 parts of concentrated sulphuric acid. The chlorochromic
acid distils over, filling the receiver with a superb ruby-red
vapor. Its density is 1*71, and it boils at 248°. Water
decomposes it, forming chromic and hydrochloric acids. It
may be preserved in tubes hermetically sealed.
675. The chromate and the bichromate of potash arc both
familiar compounds of chromic acid. The first, K0.Cr03, i&
formed on a very large scale, by decomposing the native
chromic iron with nitrate of potash, by aid of heat, Chro-
mate of potash is dissolved out from the ignited mas a, and
crystallizes in anhydrous yellow crystals. It ia is amorphous
with sulphate of potash, dissolves in two parts of cold water,
and is the source of all the preparations of chromium.
Bichromate of potash K0.2Cr08 is formed by adding
sulphuric acid to a solution of the yellow ehr ornate, when
half the potash is removed, and the bichromate crystallises
Give its properties. Describe the chlorids of chromium. Describe chlo*
rochromic acid. 575. How is chromate of potash formed ? How is bi-
chromate of potash formed ?
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NICKEL. 339
by slow evaporation in brilliant red* crystals of a rhombic
form, which are soluble in ten parts of cold water.
576. ChromateofLead— Chrome YeUow— (PbO.Cr08)is
*he well-known pigment prepared by precipitating the nitrate
or acetate of lead by a solution of chromate or bichromate
of potash. Chrome Green is the oxyd of chrome, prepared
in a particular way.
NICKEL.
Equivalent, 29*6. Symbol, Ni.
577. Nickel is rather a rare metal. It is prepared from
the speiss or crude nickel of commerce. It is white and
malleable, having a density of 8 to 8*8, and fuses above
3000°. Reduced from its oxyd by hydrogen (fig. 373) at a
low temperature, it takes fire in the air. The compact metal
is not easily oxydized. It is the only metal beside iron and
cobalt which is magnetic. This property it loses when heated
to 700°. Meteoric iron almost invariably contains nickel,
Sometimes as much as 10 per cent. Its chief ores are cop-
jper-nickel and speiss-cobalt.
Arseniuret of nickel and cobalt is found at Chatham,
Conn., and oxyd of cobalt and manganese in Mine-la-Motte,
Mo. The emerald nic7cely a beautiful green hydrous car-
bonate described by the author, is found in Lancaster Co.,
Pa. Its formula is 3(NiO)C02+6HO.
578. There are two oxyds of nickel. The protoxyd NiO
is prepared by precipitating a solution of nickel by caustic
potash : this is soluble in ammonia. It gives a grass-green
hydrated oxyd, which, by heat, loses its water and becomes
gray. The oxyd of nickel is isomorphous with magnesia,
and has been obtained crystallized in regular octahedrons.
The salts of this oxyd have a fine green color, which they
impart to their solutions.
The peroxyd of nickel NiOa is a dull black powder, of
no particular interest.
579. The sulphate of nickel NiO.S03+7HO is a finely
crystallized salt, occurring in green prisms, which lose their
576. What is chrome yellow? What chrome green? 577. In what
state does nickel occur in nature ? Describe its properties. What of its
magnetic property ? 578. What are oxyds ? In what form does the prot-
oxyd crystallize ? 579. Describe the sulphate and oxalate of nickel.
Digitized
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840 METALLIC ELEMENTS.
water of crystallization by heat. It forms beautiful, well
crystallized double salts, with the sulphates of potash and
ammonia. Oxalic acid precipitates an insoluble oxalate of
nickel from the solution of the sulphate, and the metallic
nickel is easily obtained from the oxalate by heat.
Nickel is chiefly employed in making German silver, a
white malleable alloy, composed of copper 100, zinc 60, and
nickel 40 parts.
COBALT.
Equivalent, 29-5. Symbol, Co.
580. Cobalt is a metal almost always associated with
nickel, and closely resembling it in many of its reactions.
When pure it is a brittle, reddish-white metal, with a density
of 8*53, and melts only at very high temperatures. It is
nearly as magnetic as iron. It dissolves with difficulty in
strong sulphuric acid, and is not oxydized in air. It form*
two oxyds every way analogous to those of nickel. Its prot-
oxyd is a grayish-pink powder, very soluble in chlorohydric
acid. It forms pink salts. This oxyd occurs native.
The chlorid of cobalt CoCl is formed by dissolving the
oxyd in hydrochloric acid. The solution is pink, and when
very dilute may be used as a blue sympathetic ink, which
may be made green by mixing a little chlorid of nickel.
Writing made with this on paper is colorless when cold, but
becomes of a fine blue or green when gently warmed, and
loses its color again on cooling.
The salts of cobalt and nickel are isomorphous with those
of magnesia. They are not thrown down by sulphuretted
hydrogen, but give blue or green precipitates with potash,
soda, and their carbonates. The same precipitates with
ammonia are soluble in excess of that reagent. Oxyd of
cobalt imparts a splendid blue to glass, and the pulverized
glass of this color is called smalt and powder blue. Zaffre
is an impure oxyd of cobalt, used to give the blue color to
common earthenware.
What is the composition of German silver ? 580. What are the charac-
ters of cobalt? What interesting experiment is mentioned with the
chlorid ? With what oxyd are the oxyd of cobalt and its salts isomor-
phous ? What use is made of the oxyd of cobalt ?
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ZINC.
341
ZING.
Equivalent, 32-.5. Symbol, Zn. Density, 6-86 to 7*20.
581. Zinc is an important and rather common metal. It
is not fonnd native, but a peculiar red oxyd of zinc abounds
at Sterling, New Jersey, and calamine or carbonate of zino
is found abundantly in many places. The ores of zinc are
reduced by heat and charcoal, in large crucibles closed at
top, but haying a clay tube a b
descending from near the top, as in
fig. 376, through the crucible and its
support B, to a vessel of water C.
The cover is luted on and the heat
raised. The metal, being volatile,
rises in vapor, which descending
through the tube, is condensed in
the water below. This is called
distillation per descensum.
582. Zinc is a bluish-white metal,
easily oxydized in the air, and crys-
tallizes in broad foliated laminae,
well seen in the fracture of an ingot g* 376#
of the commercial metal. It is called spelter in the arts,
and is largely used to alloy copper in forming brass, to form
sheet zinc, and also for the protection of iron in what is called
galvanized iron. Zinc is not a malleable metal at ordinary
temperatures, but at a temperature of between 250° and 300°
it becomes quite malleable, and is then rolled into sheet
zinc. At about 390° it is again quite brittle, and may be
granulated by blows of the hammer : at 773° it melts, and
if air has access to it, it takes fire, and burns rapidly with a
brilliant whitish-green flame, giving off flakes of white oxyd
of zinc, anciently called lana philosophica and pompholix.
It is completely volatile at a red heat. We constantly em-
ploy zinc in the laboratory to procure hydrogen, and granu-
late it by turning it slowly into cold water from some height.
It dissolves in solutions of soda and of potassa, with evolu-
tion of hydrogen and formation of zincate of the alkali
employed.
583. The oxyd of zinc ZnO is formed when zinc burns
5S1. Hew is sine reduced from ite ores? How distilled? 582. Whai
arc it* properties ? At what temperature is it malleable ?
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342 METALLIC ELEMENTS.
in air. Only one oxyd is known. It is, when pure, a white
powder, yellowish while hot. It contains zinc 80*26, oxygen
19*74. It is insoluble in water, but forms a hydrate with it.
The anhydrous oxyd mingled with drying- oils forms a valu-
able paint, now coming into use in place of white-lead. It
has the advantage of not changing by sulphuretted hydro-
gen and of not being deleterious to the health of the work-
men. It is now largely manufactured from the red zinc of
New Jersey, and from the franklinite of the same region,
which contains a large quantity of zinc.
Calamine is a native carbonate of zinc ZnO.COfl, and
is its most valuable ore. Electric calamine is a silicate
8(ZnO)SiOs+l}HO.
Chlorid of zinc ZnCl is a valuable escarotic, and has
been much used in dilute solution to preserve anatomical
subjects for dissection.
Sulphuret of zinc, Blende, ZnS, is one of the most common of
the ores of zinc. It occurs in beautiful brilliant crystals, modi-
fications of the first system, called by the miners black-jack.
Sulphate of Zinc, or White Vitriol, ZnO.S08+7HO.-—
This salt has the same form as the sulphate of magnesia, and
looks extremely like it. It dissolves in 2} parts of cold
water, at 60°, but at 212° is indefinitely soluble, as it then
fuses in its own crystallization water. It forms double
salts with the sulphates of ammonia and potash. It is a
powerful and very rapid emetic.
Sulphuret of ammonia throws down a characteristic white
precipitate of sulphuretted zinc from its neutral solutions
CADMIUM.
Equivalent, 56. Symbol, Cd. Density, 8*7.
584. Cadmium is generally found associated with zinc.
It is quite malleable, white, and harder than tin. It fuses
at 442°, and volatilizes completely at a temperature a little
above this. It is not easily oxydized, and is but slightly
soluble in chlorohydric or sulphuric acid*. Nitric acid dis-
solves it with ease, forming a salt from which sulphuretted
hydrogen throws down a very characteristic orange-yellow
sulphuret. This compound is also found native and crys-
tallized, (greenockite.*)
583. Describe the oxyd ZnO. What large use is being made of it?
What is calamine ? Blende ? Sulphate of zinc ? What of its solubility ?
584. What are the properties of cadmium ?
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LEAD. 843
Its oxyd CdO is a bronze powder, formed by igniting tho
nitrate or carbonate, and rises in a brown vapor when cad-
mium is placed in the focus of the oxyhydrogen blowpipe.
LEAD.
Equivalent, 103*5. Symbol, Pb. Density, 11-45.
585. This useful and familiar metal occurs in boundless
profusion in this country. Its chief ore is galena, or sul-
phuret of lead, from which the metal is easily obtained by
smelting with a limited amount of fuel at a low heat. The
carbonate, phosphate, chromate, and arseniate are also na-
tural salts of lead, much prized by the mineralogist.
Lead is a bluish-gray metal, very soft and ductile, but not
very tenacious, (471 ;) it oxydizes in the air quite rapidly,
forming a coat of oxyd, or carbonate, which usually protects
it from further corrosion. Its destiny is 11-45, and it fuses
at about 630°; when melted it combines rapidly with oxygen
from the air, forming either protoxyd, or red oxyd, accord-
ing to the degree of heat employed. It is somewhat volatile
above a red heat.
Lead is acted upon by distilled water and by rain water.
Water, by reason of its affinity for the oxyd of lead, acts
like an acid upon metallic lead. A bright slip of pure lead
is tarnished almost immediately in pure water, and after a
short time becomes covered with a pellicle of carbonate of
lead ; while the water yields a dark cloud to sulphuretted
hydrogen, showing the presence of oxyd of lead dissolved in
it. It is, therefore, unsafe to use water-pipes of lead, unless
it has been proved by experiment that the particular water
in question does not act on this metal. The carbonate, which
is the salt generally produced under these circumstances, is
an energetic poison. The presence of a very small quantity
of foreign matter in water, and especially of the sulphate of
lime, usually arrests this action, and renders the use of lead-
pipes in a majority of cases not hazardous.
Lead does not easily dissolve in strong acids, except in
nitric, with which it forms a soluble salt : strong sulphuric
acid dissolves it only when heated, forming nearly insoluble
sulphate of lead.
685. What is the chief ore of lead ? What are the properties of lead?
Its density and fusion point? Is it volatile ? What acts on lead ? What
salt of lead is most poisonous ? What arrests the action of water on V«* •
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344
METALLIC ELEMENT8.
Th ire are three oxyds of lead, viz. suboxyd PbaO, prok
oxyd PbO, and peroxyd, or plumbic oxyd PbOa.
586. Protoxyd of Lead, Litharge, Massicot, PbO. — This
oxyd is a yellow powder, formed by slowly oxydizing lead
with heat. It is slightly soluble in water, and the solution
is alkaline : in solution of sugar it is largely soluble. It
fuses easily, and dissolves silica with great rapidity; hence its
use in glazing pottery (555) and in the manufacture of glass,
(553.) It forms a large class of definite salts, which have
often a sweet tafcte, as is seen in the acetate, or sugar of lead.
The peroxyd Pb09 is prepared by acting on the red-lead
. with dilute cold nitric acid : it is a puce-colored body, which
plays the part of an acid, forming salts with bases. The
oxyd of lead forms insoluble salts with the fatty acids, of
which the well-known diachylon plaster is an example.
There are several intermediate oxyds of lead, called miniums
which are of variable composition, according to the tempera-
ture at which they are prepared. Red-lead is a familiar ex-
ample of these. Its formula is Pb304 or 2PbO.Pb09. It
has a fine orange-red color when well prepared, and is some-
times found crystallized in the fissures of the furnaces. It
is prepared by exposing lead to a constant temperature of
about 700°. Acted on by hydrochloric acid, it evolves
chlorine, and, with sulphuric acid, oxygen is given off. It
is preferred to litharge for glass-making.
The chlorid and iodid of lead possess no particular inte-
rest ) the latter crystallizes in beautiful yellow scales from
its solution in hot water. The chlorid, iodid,
and sulphate are all very insoluble compounds.
Sulphuretted hydrogen throws down a black
sulphuret from all soluble salts of lead, being
the best test of its presence.
587. Zinc precipitates it from its solutions by
voltaic action, in beautiful crystalline plates of
metallic lead, which assume a branching form,
often an inch or two in length, and hence called
the lead-tree, or arbor satumi, from the alche-
Fig. 377. mistic name of this metal. The acetate is usually
employed : an ounce of the salt is dissolved in two quarts of
What oxyds of lead are there ? 586. What names has PbO ? Give
its properties. What is PbOa? What is diachylon plaster? What are
the miniums ? What use is made of minium ? What test lb named for
lead salts ? 587. How is metallic lead precipitated from its solution ?
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copper. 345
distilled water, and a piece of clean zinc suspended in it by
a thread : the precipitation is gradual, and occupies one or
two days. . The arrangement is seen in the fig. 377.
588. Carbonate of Lead, White-lead) Ceruse, PbO.C03.
— This salt is found beautifully crystallized in nature, but
is prepared artificially in very large quantities, for the pur-
poses of a paint. This pigment is obtained by casting lead
in very thin sheets, which are then rolled up into a loose
scroll Z (fig. 378) and placed in a pot over a small quantity
of vinegar u, supported on the ledge b b, so
as not to project above the pot, nor touch the ~
vinegar. The vinegar is obtained from the
fermentation of potatos. Many thousands of
these pots are arranged in successive layers
over each other, with covers n! m between, and
the interstices filled with spent tan, or ferment-
ing stable-dung, which gives a gentle heat to
the acid. After a time the lead is completely g* '
converted into an opake white crust of carbonate. The theory
of this process will be explained when we describe the ace-
tates of lead, (Organic Chemistry.) White-lead is now largely
adulterated by sulphate of baryta, but the fraud may be
easily detected by dissolving the carbonate in an acid, when
the sulphate of baryta will be left behind. Carbonate of
lead is highly poisonous.
589. Uranium, (equivalent 60.) — This rare metal is found
only in a few very rare minerals, of which the best known are
pitch blende, an impure oxyd of uranium, and uranite, one
of the most beautiful of mineral species, which is a phos-
phate of uranium. The metal is of a silver color, a little
malleable, and has so great an affinity for oxygen as to burn
in the air. It forms two oxyds, UO and U90r The salta
of uranium possess considerable chemical interest.
COPPER.
Equivalent, 31*7. Symbol, Cu. Density, 8-87.
590. Capper has been in familiar use since the times of
Tubal Cain, and is one of the most important metals to the
588. How ia the carbonate prepared, and for what is it used ? 589. In
what minerals is uranium found ? What oxyd does it form ? 590. Whai
it the history of copper ?
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846 METALLIC ELEMENTS.
wants of society. It is often found in the metallic slate*
The metallic copper of Lake Superior is found in irregular
veins, filling fissures, from which it is cut by chisels, and by
drills in huge blocks of great purity. Small masses of
silver are also often found adherent to the copper. One
mass from this region, now at Washington, weighs over 3000
pounds, and such masses are frequent. The most usual
ores of copper are the red oxyd of copper, copper pyrites,
and copper glance, a pure sulphuret, or sulphuret of copper
and iron.
The blue and green malachites, or carbonates of copper,
phosphate and arseniate of copper, and many other salts of
this metal, are also found in the mineral kingdom. Copper
is very malleable, and is the only red metal except titanium.
It fuses at 1996°, and has a density of 8*78, which may
be increased to 8 -96 by hammering. It does not change in
dry air, but in moist air becomes covered with a green coat
of carbonate, known as verdigris, (corruption of the French
vert de gris.) It is stiffened by hammering or rolling, and
softened again by heating and quenching in water. It may
be drawn into very fine wire of good tenacity, which is an
excellent conductor of heat and electricity, and is much
used in electro-magnetism and for the telegraphic conductors.
Nitric acid is the proper solvent of copper, sulphuric and
hydrochloric acids scarcely acting upon it.
591. There are four oxyds of copper, suboxyd CusO,
protoxyd CuO, binoxyd CuO^, and an acid oxyd whose
composition is unknown. *
The protoxyd, or black oxyd of copper, CuO, is the
base of all the blue and green salts of copper. It is
formed by decomposing the nitrate with heat. It is black
and very dense, quite soluble in acids, and forms many
important salts which are isomorphous with those of mag-
nesia. It yields all its oxygen to organic matters at a red
heat, and for this purpose is much used in their analysis.
The suboxyd, or red oxyd of copper, CuaO, is found
native in beautiful octahedral crystals, and is also formed
when copper is oxydized by heat. This oxyd communicates
How found at Lake Superior? What copper ores are named? Give
its equivalent and characters. What is the solvent of copper? 591.
What oxyds of copper are known ? What relative to the black oxyd
of copper ? Describe the suboxyd.
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COPPER.
347
to glass a magnificent ruby-red color. The chlorids and
iodids of copper are of no great importance.
592. Sulphate of copper, blue vitriol, CuO.S08+5HO,
is an important salt, crystallizing in large, beautiful blue
rhombs, which are soluble in four parts of cold and two
parts of hot water. It loses its water by a gentle heat and
falls to a white powder. It is much used in dyeing and for
exciting galvanic batteries. With ammonia it forms a dark-
blue crystallizable compound.
593. Nitrate of copper CuO.N05+3HO is formed by
dissolving copper in nitric acid to saturation, and is a deep-
blue, crystallizable, deliquescent salt, very corrosive, and
easily decomposed : a paper moistened with a strong solu-
tion of this salt cannot be rapidly dried without taking fire,
from the decomposition of nitric acid. The residues of
operations for obtaining deutoxyd of nitrogen (341) afford
an abundant supply of this salt in the laboratory.
Ammonia detects the smallest traces of this metal in
solution, by the deep violet-blue of the ammoniacal salt of
copper which is formed. Iron precipitates it from its acid
solution as a brilliant red coating. Copper is a metal most
readily obtained in a metallic form from its solutions by
voltaic decomposition. The sulphate is usually employed for
this purpose in the electro-
type, the arrangement be
ing made like fig. 379, the
operation of which has
been already explained in
section 234. The alloys
of copper are much prized
for their various useful
applications in the arts.
Brass is zinc &, copper i .
Dutch metal, of which thin
leaves are made, contains
10 to 14 of zinc.
Fig. 379.
592. Describe the sulphate of copper. 593. What is the nitrate ? How
does it affect organic matter ? How is copper detected? Why is cop-
per used in electrotyping ? What of its alloys ?
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848 METALLIC ELEMENTS.
CLASS V. METALS WHOSE OXYDS ARE WEAK BASES
OR ACIDS.
594. The five first metals in this class are so rare that
we may pass them with a very brief mention. They are
vanadium, tungsten, columbium, titanium, and
Molybdenum.
Vanadium appears to be closely allied to chromium.
The vanadic acid V08 fornjs salts with lead and copper,
found native as vanadinite, and volborthite CuO. V08.
Tungsten, so named from its great weight, (12*11,) exists
as tung3tic acid W08 in wolfram and schedetine CaO.W08
or tungstate of lime. . Native tungstic acid has been observed
in Monroe, Conn. : it is a yellow powder, soluble in ammo-
nia, but insoluble in acids.
Columbium, or tantalum, is the metal of a mineral called
columbite, (in allusion to its American origin, by Hatohett,
its discoverer,) or tantalite, a salt of iron in which this metal
is the acid. It forms two oxyds, TaOfl and Ta08, both acids.
It is with the columbite of Haddam that the, two new
metals, pdopium and niobium, are found, as described by
Rose.
Titanium is a copper-red metal, crystallizing in cubes.
It forms with oxygen titanic acid TiOfl, a substance found
pure in three distinct minerals, viz. rutile, anatase, and
Brookite, an interesting case of trimorphism. This acid is
soluble in strong chlorohydric acid, but precipitates, on di-
lution and boiling, a white, insoluble powder, much resem-
bling silica. It is used to give a yellowish tint to porcelain
in preparing artificial teeth.
Molybdenum is a white, slightly malleable, infusible metal,
density 8*6. The sulphuret is a common mineral distributed
in primitive rocks: it resembles graphite. It forms with
oxygen oxyd of molybdenum MoO, binoxyd MoOfl, and mo-
lybdic acid MoOs, which is its most important compound*
Molybdic acid forms soluble salts with the alkalies, of which
the molybdate of ammonia is the most valuable, being the
594. What is vanadium ? What is tungsten ? In what minerals found ?
What is columbium ? In what mineral found ? What new metals hare
been found with it? What is titanium? What is titanic acid? What
natural forms has it ? How is molybdenum found in nature ? What im-
portant salt does it form ?
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tin. 349
most delicate test known for phosphoric acid. Molybdate of
Jead is a beautiful native salt of this acid. Heat converts
the sulphuret into the impure acid, and it is also oxydized
directly by monohydrated nitric acid.
tix. f
Equivalent, 59. Symbol, Sn, (Stnanum.) Density, 7*29. •
595. Tin is one of those metals which have been known
from the most remote antiquity. The mines of Cornwall
have been worked for the oxyd of tin since the times of the
Phoenicians and Greeks. It has been found in this country
only at Jackson, N. H., in small quantities. Tin is a white
metal with a brilliant lustre, not easily tarnished, and resist-
ing the action of acids to a remarkable degree. It is soft,
very ductile, laminable, malleable, but of feeble tenacity.
Tin foil is made of one-thousandth of an inch in thickness,
or even much thinner. A bar of tin when bent gives a pe-
culiar crackling sound, familiarly called the cry of tin, due
to the disturbance of its crystalline structure. It is one
of the best conductors of heat and electricity.
596. Tin has a density of 7*29, and fuses at 442°. Its
alloys are very valuable ; gun-metal (copper 90, tin 10) is
one of the strongest alloys known, of a reddish-yellow ; bell-
metal (copper 78, tin 22) is a very sonorous and brittle
alloy, of a pale yellow ; and speculum-metal (copper 70 to
75, and tin 25 to 30) is a hard, brilliant, almost white, and ex-
cessively brittle alloy. Pewter is a mixture of tin and anti-
mony or lead. Tin-plate is only sheet-iron coated with tin.
Chlorohydric acid dissolves tin with escape of hydrogen,
forming SnCl.
Strong nitric acid does not dissolve tin, but the addition
of a little water to the acid causes a violent action, and the
tin is speedily converted to stannic acid SnOa.
597. There are two oxyds of tin : 1. The protoxyd SnO;
and 2. The peroxyd SnOa. There are numerous intermediate
oxyds formed of these two. 1. This is obtained by preci-
pitating a solution of protochlorid of tin with an alkaline
595. What history is given of tin ? What are its equivalent and general
properties? 596. Give its density and fusibility? What is said of its
alloys with copper ? What is tin-plate and pewter ? How does nitric
acid affect it ? 597. What ozyds of tin are there ? What is the nrot-
oxyd.
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850 METALLIC ELEMENTS.
carbonate, which yields a bulky hydrate ot the protoxyd.
It is a very unstable compound, passing into the peroxyd at
a very moderate heat. 2. The peroxyd is found native in
the beautiful crystallized tin stone. It may be obtained in
a soluble and an insoluble condition. When the perchlorid
1 is precipitated by an alkali, the bulky white precipitate of
hydrated peroxyd which appears is easily soluble in acids;
but if tin is acted on by an excess of moderately strong
nitric acid, a white insoluble powder is formed, which is
not acted on by the strongest acids. Heat converts both
into a lemon-yellow powder, which dissolves in alkalies, but
not in acids, and which is known as stannic acid : it reddens
test-paper, and forms salts. The putty used to polish stone
and glass is the peroxyd of tin
598. Protochlorid of tin SnCl which is prepared by
dissolving tin in hot chlorohydric acid, is a powerful de-
oxydizing agent, and reduces the salts of silver, mercury,
platinum, &c, to the metallic state. The anhydrous proto-
chlorid is formed by heating protochlorid of mercury with
powdered tin.
599. Perchlorid of tin SnCla is a dense fuming liquid,
long known as the fuming liquor of Labavius. It is formed
by distilling a mixture of 1 part of powdered tin and 5 of
corrosive sublimate. The tin mordant used by the dyers is
formed by dissolving tin in chlorohydric acid, with a little
nitric acid, at a low temperature, or by passing chlorine gas
through the protochlorid.
The sulphurets of tin correspond to the chlorids. The
bisulphuret (aurum musivum) is used as a bronze color for
imitating gold in ornamental painting and printing, and also
to excite electricity in the electrical machine, (166.)
The aichemistic name for this metal was Jove, and the
medicinal preparations of tin are still called jovial prepa-
rations.
BISMUTH.
Equivalent, 208. Symbol, Bi. Density, 9*8.
600. Bismuth is found native, and also in combination with
Describe the peroxyd. What two modifications of it are named ? How
does heat affect them ? What is " putty V 598. How is protochlorid of
tin employed as a reagent? 599. What is perchlorid of tin, and how
prepared ? What is the tin mordant ? What sulphurets of tin are there t
What was its aichemistic name ?
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BISMUTH. &51
other substances. Native bismuth is found in the United
States, at Monroe, Conn. It is a brittle, highly crystalline
metal, of a reddish-white color, with a density of 9*8, and
fuses at 507°. It is obtained in large and beautiful obtuse
rhombic crystals, by fusing several pounds of bismuth in an
earthen pot, purifying by successive portions of nitre, and
leaving it to cool until a crust is formed on its surface,
which is pierced by a hot coal and the still fluid interior
turned out. The vessel will be lined with a multitude of
brilliant crystals.
It dissolves in nitric acid, but, like other metals of this
class, does not decompose water under any circumstances.
601. Two oxyds of bismuth are known. The protoxyd
BiOs is formed by gently igniting the subnitrate. It is a
yellowish powder, easily soluble in acids, and is the base of
all the salts of bismuth. It is, however, a very feeble base,
since even water decomposes its salts. The peroxyd Bi05
is not of much interest.
602. The nitrate of bismuth Bi08.N05+ 3HO is the most
interesting of its salts. It may be obtained from a strong
solution in large transparent crystals, which are decomposed
by water. The solution of the nitrate of bismuth turned
into a large quantity of water is immediately decomposed,
with the production of a copious white precipitate of subni-
trate of bismuth. This is owing to the superior basic power
of the water, which takes a part of the nitric acid. The
white precipitate is a basic nitrate Bi08.N05-j-3BiOsHO.
This white oxyd has been much used as a cosmetic. It
blackens by sulphuretted hydrogen.
603. The alloy of bismuth, known as Newton's fusible
metal, is formed of 8 parts bismuth, 5 parts lead, and 3 parts
tin, and melts at about 208°, (473.) It is much used in
taking casts of medals. An alloy of 1 lead, 1 tin, and 2
bismuth, fuses at 200°-75. The expansion of bismuth in
* cooling renders it a valuable constituent of alloys where
sharpness of impression in casting is important.
600. What is the color and fusibility of bismuth ? Describe its crys-
tals, and the mode of obtaining them. 601. How many oxyds has this
metal? 602. What is the most interesting property of the nitrate ? What
use is made of the subnirate ? 603. What its the composition of Newton'*
foible metal ? What more fusible alloy is named ?
Digitized
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4*52 METALLIC ELEMENTS.
ANTIMONY.
Equivalent, 129. Symbol, Sb, (Stibium.) Density, 67.
604. This metal is derived chiefly from its native suU
phuret, which is a rather abundant mineral. The metal is
obtained by fusing the sulphuret with iron-filings, or car*
bonate of potash, which combine with the sulphur and set
free the metal. It is a white, brilliant metal with a blue
tint, forming broad rhomboidal crystalline plates in the com-
mercial article, but fine granular if purified from foreign
metals, which cause it to assume a coarse crystallization.
It is very brittle, and, like bismuth, may be reduced to a fine
powder. It fuses at about 842°, and lower if quite pure :
a high fusion point is a sign of its impurity. It is, in a cur-
rent of hydrogen, entirely volatile, but alone and covered
very slightly so. It dissolves in hot chlorohydric aoid, but
nitric acid converts it into the insoluble white antimonic
acid.
Its alloy with lead is type-metal, which, like the alloys
of bismuth, gives very sharp casts, by reason of the expan-
sion it undergoes at the moment of solidification, which
forces the metal into all the fine lines of the mould. It is
remarkable that both of the constituent metals shrink when
cast separately. Finely powdered antimony is inflamed in
chlorine gas, forming the perchlorid.
605. Two oxyds of antimony are known, viz :
1. Antimonic Oxyd, Sb03. — This oxyd may be obtained
by digesting the precipitate from chlorid of antimony by
water, with carbonate of potash or soda, or by burning anti-
mony in a red-hot crucible ; and also by subliming it from
the surface of fused antimony in a current of air. It is
a fawn-colored insoluble powder, anhydrous, and volatile
when highly heated in a close vessel. Boiled with cream
of tartar, (acid tartrate of potash,) it forms the well-known %
tartar emetic, which may be obtained in crystals from the
solution.
The glass of antimony is an impure fused oxyd, pre-
604. How is antimony obtained? What are its properties? What of
it* grain ? Its fusion ? Its alloys ? 605. How many compounds does
antimony form with oxygen ? What important salt does the oxyd form
wit) totash?
Digitized
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ANTIMONY. 353
pared for the purpose of making tartar emetic. Heated
in air, this oxyd gains another equivalent of oxygen, and
forms —
2. Antimonic acid Sb05 is formed, as already stated,
when antimony is digested in an excess of strong nitric acid,
or better in aqua-regia with nitric acid in excess. It
dissolves in alkalies, with which it forms definite salts, that
are again decomposed by acids, hydrate of antimonic acid
being thrown down. The hydrate loses its water below a
red heat, becoming a crystalline fawn-colored powder; and
by a higher heat one equivalent of oxygen is expelled, anti-
monious acid being formed.
606. There are chloride and sulphuret* of antimony cor-
responding to the oxyd and to antimonic acid.
The tercMorid, butter of antimony, SbCl8, is made by
distilling the residue of the solution of sulphuret of anti-
mony in strong hydrochloric acid, (fig. 317.) When a drop
of the distilled liquid forms a copious white precipitate on
falling into water, the receiver is changed, and the pure
chlorid is colleoted. It is a highly corrosive fuming fluid,
and by cooling forms a crystalline deliquescent solid. It is
used in medicine as a caustic. Water decomposes it, but it
dissolves in hydrochloric acid unchanged : water poured
into the solution throws down a bulky precipitate, which is
a mixture of oxyd and chlorid of antimony, and has long
been known by the name of powder of algaroth, SbCl8.
2Sb08.
The bromid of antimony is a crystalline volatile com-
pound.
607. The tersulphuret of antimony SbS8 constitutes the
common commercial sulphuret, and the beautiful crystal-
lized native mineral, antimony glance.
The pentasulphuret of antimony SbS5 is formed by boil-
ing the tersulphuret with potash and sulphur, and throwing
down the compound in question by an acid, as a golden yel-
low sulphuret, known by the name of sulphur auratum,
or golden sulphur of antimony. More generally, however,
the decomposition on adding an acid, as above, gives us
the oxysulphuret of antimony SbSs+Sb08, which is a
What is antimonic acid? 606. Describe the terchlorid? How de-
decomposed ? 607. What is said of the sulphurets ? What are the golden
sulphuret and kerme$ mineral t
23
Digitized
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S54 METALLIC ELEMENTS.
characteristic reddish-orange precipitate. This is the sab*
stance known as kermes mineral, and is an article of the
older medical practice. The solution of sulphuret of anti-
mony in caustic potash and sulphur is a case in which
sulphuret of potassium is a sulphur base, and sulphuret of
antimony a sulphur acid.
The formation of tartar emetic with tartaric acid, and
the production of the characteristic reddish-yellow sulphu-
ret of antimony with sulphydrio acid are the most signal
tests of antimony. The sulphydrate of ammonia produces
the same colored precipitate, but this is soluble in excess of
the precipitant, as the former also is in the solution of al-
kalies. The blowpipe also furnishes good evidence : when
a bit of metallic antimony is fused under the oxyhydrogen
blowpipe it volatilizes and burns, and if it be thrown on
the floor or an inclined board, it scatters in numerous burning
globules, whose path is marked by a white stain of oxyd
of antimony. We will, under arsenic, mention how anti-
mony is to be distinguished in cases of poisoning.
ARSENIC.
Equivalent, 75. Symbol, As. Density, 5-8.
608. Metallic arsenic is found native in thick crusts,
called testaceous arsenic, evidently deposited by sublimation.
It is, however, more usually obtained in the form of arseni-
ous acid As08, from roasting the ores of cobalt, nickel, and
iron, with which metals it is often combined. Mispickel, a
double sulphuret of iron and arsenic, is a great source for
this metal. The vapors of arsenious acid given out in the
roasting are condensed in a long horizontal chimney, or in
a dome constructed for the purpose ; the first product being
purified by a second sublimation. Arsenic is a brilliant
crystalline steel-gray metal, brittle, and easily pulverized.
In vessels free from air it may be sublimed unchanged at a
temperature of dull redness. Its vapor is colorless, very
dense, (10*37,) and has a remarkable odor, resembling garlie.
The garlic odor is well perceived on subliming a fragment of
What is the nature of this salt? What are the best tests of antimony?
How does it act under the blowpipe? 608. How is arsenic found, and
in what minerals ? What are its properties ? How is it sublimed un-
changed ? What is the density and odor of its vapor?
Digitized
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ARSENIC.
355
arsenic or of arsenious acid from a live coal. It sublimes
without fusion. It may, however, be fused in tight vessels
under pressure of its own vapor. Metallic arsenic soon
tarnishes in air and assumes a dull cast-iron look.
It is sold by druggists under the absurd names of
fly-powder} cobalt, and mercury — names intended
to deceive and likely to mislead, involving obvious
danger. Metallic arsenic is easily obtained in distinct
crystals by subliming the commercial metal, or
arsenious acid, mingled with charcoal and carbonate
of soda, or black flux, (484,) in a tube of hard glass,
or, if a larger quantity is required, in a small retort.
The mixture is put in a 5, (fig. 380,) and heated to
redness while the air is shut out. The metal rises
and is deposited in a black metallic mirror in the cool
part of the tube just above. Metallic arsenic is an
active poison. It burns in the air with a blue
flame, and it is also inflamed in chlorine gas. Fis- 380«
609. The oxyds of arsenic are, 1. Arsenious acid AsO„
and 2. Arsenic acid As05.
1. Arsenious Acid — White Arsenic — RatJs-bane9 As08;
—This well-known and fearful poison is formed, as just
stated, when metallic arsenic is sublimed in air, or when
any of the ores of arsenic are roasted. This oxyd is what is
usually meant when the term arsenic is used in commerce.
When newly sublimed, it is a hard transparent glass, brittle,
and with a density of 3*7. It slowly changes to a white
opake enamel, resembling porcelain. This change is gradual,
the vitreous portions being still found in the centre of the
opake masses. As sold in commerce, it is usually reduced
to a white powder, rarely* found without adulteration. It
sublimes at 380°, without change, and crystallizes in bril-
liant octahedrons, as may be well seen by slowly subliming
a small quantity in a glass tube. Its vapor is inodorous,
but if sublimed from charcoal it gives the peculiar garlic
odor of metallic arsenic, being reduced to that state. It is
soluble in about 10 parts of hot water, and is almost taste-
less, with a faint sweetish flavor, which renders it the more
How may it be fused ? How does air affect it? What names has it?
How obtained crystallized? 609. What oxyds does it form? Give formu-
las. What is arsenious acid? What are its common names ? What aro
its characters? What change does it suffer ? How does it crystallize ? How
soluble ? What of its taste ?
Digitized
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856 MBTALWO ELEMENTS.
dangerous poison, since no warning is given to the victim
who takes it, as in case of most other metallic poisons. The
vitreous acid is three times as soluble as the opake. The
solution in water is acid to test-paper, and deposits nearly
all its arsenic in crystals on cooling, retaining 1 pari
to 30 of water. Chlorohydric acid dissolves arsenic, and
if a solution of 4 parts AsOs in 6 of HCi and 2 of water
is slowly cooled from boiling, the AsOs is deposited in trans-
parent octahedrons, and if in the dark, the formation of each
crystal is accompanied by a spark, and sometimes the light
produced is such as to illuminate a dark room. The alka-
lies dissolve arsenic, but do not form crystallizable salts with
it. Arsenious acid contains As 75-75, O 24-25.
610. Arsenic Acid, As05. — This acid is formed by adding
nitric acid to the solution of white arsenic in hydrochloric
acid, as long as any red vapors of nitrous acid show them-
selves, and then carefully evaporating the solution to entire
dryness : a white porous subcrystalline mass remains, which
is slowly soluble in water. Its solution is a powerful acid,
quite similar in chemical characters to phosphoric acid. The
analogy is so great that there is a complete similarity in con-
stitution, and even in external appearance, between all the
salts of these two acids. For every tribasic phosphate we
have an arseniate, not only similar in constitution, but iso-
morphous, and so resembling it in all its external properties
as not to be distinguished by the eye. Thus the tribasic
phosphate of soda (512) and the tribasic arseniate of soda,
are —
Phosphate of soda H02NaO.PO,-r-24Aq.
Arseniate of soda H02NaO.AsO,-f-24Aq.
These, and many other facts, lead to the opinion that the
elements are themselves isomorphous; and in fact arsenic has
no claim to the metallic character but its lustre, being in
chemical properties and natural affinities associated with
phosphorus.
611. The chlorid of arsenic AsCl8 is a fuming volatile
liquid, decomposed by water, and very poisonous. The
bromid and iodid are both crystallizable solids, also decom-
posed by water.
What is said of its chlorohydric solution ? 610. How is AsOi formed?
What are its properties? What analogy has it with PO»? To what
opinion do these facts lead ? 611. What of chlorid of arsenic ?
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ARSENIC. 857
The sulphurets of arsenic are natural compounds, used an
pigments, and also in pyrotechny. The first, AsS2, is a red
transparent body, called realgar, and AsS2 is the golden-
yellow orpiment Both these substances are found native,
and are usually associated. They are brought from Koor-
distan in Persia, and from China. The Mohammedans use
the yellow orpiment as a depilatory in their ceremonial puri-
fications. Two higher sulphurets may be formed, which aie
As05 and AsO- : the former is the product thrown down
by sulphuretted hydrogen in a solution of arsenic. The
sulphurets are soluble in alkalies and in sulphydrate of am-
monia.
612. Arseniuretted Hydrogen, AsH8. — This is a gas pro-
duced by the action of dilute sulphuric acid on an alloy of
line and arsenic, or by the evolution of hydrogen in presence
of arsenic or arsenious acid.
Figure 381 shows the ordinary
gas evolution bottle A, in which
are the materials for producing
hydrogen. An arsenical solution
poured in at n m, immediately
changes the color of the flame
at 6; before colorless, it now
becomes of a peculiar blue, and
evolves a cloud of arsenious acid, Fig. 381.
or deposits metallic arsenic on a cold surface. Marsh's test
for arsenic depends on the generation of this gas. It is a
virulent poison of the most active description. This gas is
readily absorbed by a solution of sulphate of copper, and
precipitates an arseniuret of that metal. Its density is 2*69 :
it has a peculiar disgusting odor, and is decomposed by heat
alone with deposition of metallic arsenic. It is liquid at
— 22°F. : water dissolves it slightly, and chlorine completely
decomposes it with flame.
Detection of Arsenic in Poisoning.
613. The too frequent use of arsenic as a means of destroy-
ing human life renders it of the greatest moment to know
certain processes for its detection. Arsenic is almost always
What are the sulphurets ? 612. What is arseniuretted hydrogen ? Ea*
produced? What of its flame? What are its properties? 613. What
of arsenical poisoning ?
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J558 METALLIC ELEMENTS.
fatal when it has time to become absorbed by the circulation
in sufficient quantity. The most reliable antidotes which
have been proposed are the moist hydrates of sesquioxyd
of iron and of caustic magnesia. With both these arsenic
forms insoluble salts. The alkalies, being solvents of arsenic,
only increase the danger by favoring absorption.
We enumerate a few of the tests for arsenious and arsenic
acids:
1. Sulphydric acid produces in acid or neutral solutions
of As08 and As05 a rich orange-yellow precipitate, (orpi-
ment,) soluble in ammonia and alkalies, and in sulphydrate
of ammonia, but precipitated again by acids.
2. Nitrate of silver and ammonia-nitrate of silver pro-
duce in solutions of arsenious acid a lemon-yellow precipitate,
(arsenite of silver,) soluble in nitric acid. In solutions of
arsenic acid they produce a brick-red precipitate.
3. Ammonio-svlphate of copper gives a brilliant green
precipitate (Scheele's green) in alkaline or neutral solutions of
arsenious acid, which precipitate (arsenite of copper) is soluble
in excess of ammonia.
4. A slip of bright metallic copper, placed in a boiling
solution of arsenic or arsenious acid made acid by chloro-
hydric acid, is soon coated with a gray deposit of metallic
arsenic. This is called Reinsch's test, and is applicable even
in presence of organic matters which vitiate, partially or
wholly, the previous tests.
5. Reduction of the metal from the oxyds or sulphurets
is justly esteemed in judicial investigations as the most reli-
able of all* tests. This is accomplished by several modes.
^ The oxyds or sulphurets are mra-
4* gled with finely-powdered charcoal
and carbonate of soda or cyanid
of potassium and placed in a small
tube a d (fig. 382) of hard glow.
The part a b is heated red hot,
Fig. 382. when, if arsenic is present, it is
sublimed in a black metallic mirror at c. A small tube is
used, because in many cases very minute portions are opo-
What are antidotes, and why? How does sulphydric acid act as a test
of arsenic ? How nitrate of silver and ammonia ? How ammonia-sul-
phate of copper? What is Reinsch's test? What of the reduction pre-
ferred? Describe from fig. 382.
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ARSENIC.
859
Fig. 383.
rated on. In order to prove the character of this ring, the
tube is broken off at by (fig. 383,) and the
flame of a spirit-lamp applied cautiously
while the tube is gently inclined. A
current of air passing over the ring of
metal converts it to arsenious acid, which
lines the cooler parts of the tube with
small brilliant octahedrons of a size
visible by a magnifier. If further proof
were required, a current of sulphydric
acid will convert the white crust into yellow orpiment,
wholly soluble in ammonia, precipitated by chlorohydrio
acid, and insoluble in that menstruum.
6. Marsh's test, by means of arseniuretted hydrogen, gives
unequivocal testimony when arsenic is present Fig. 384
shows a convenient form of the apparatus used
for this purpose, which is more simply arranged
as in fig. 381. This apparatus has the conve-
nience of a cock to regulate the escape of the
gas. The zinc is in the lower bulb— the acid
water and suspected substance are introduced
by the upper bulb. The zinc and all the
materials employed must be scrupulously ex-
amined as to freedom from arsenic. For this
purpose the flame of hydrogen must not give the
least spot upon clean porcelain. On adding
the arsenical solution, however, the flame be-
comes livid, larger, gives off white vapors, and
deposits a tache or spot, in the form of brown- Fifr 88*#
black mirror, on the surface of porcelain, as in fig. 385.
Antimony gives a similar spot, which is liable to be con-
founded with that from arsenic. It is, however, more sooty-
black. Exposed to vapor of iodine in a small capsule, anti-
mony spots turn reddish orange, while arsenic spots appear
orange yellow, and soon vanish entirely. Exposed for a
moment to vapor of chlorine given off from bleaching-pow-
ders in a capsule, the spots being on the underside of the
cover of the same, the spots disappear. If a drop of nitrate
of silver be then let fall on the flat surface, if arsenic was
How is it oxydised in fig. 383 ? What further proof may be had ? What
is Marsh's test ? Describe fig. 384. What care is required ? What effect
Is seen on introducing an arsenic solution ? What gives a similar spot ?
How are the spots distinguished ? How by chlorine and nitrate of silver I
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260
METALLIC ELEMENTS.
present there will be a brick-red stain visible, amounting to
a precipitate if much of the metal existed — while antimony
does no such thing. These distinctions are conclusive.
The arrangement of Marsh's apparatus recommended by
the commission of the Paris Academy, in cases of judicial
investigation, is shown in fig. 385. The evolution bottle A
Fig. 385.
is provided with a bulb-tube a b, to retain moisture, which is
more effectually removed by the chlorid of calcium tube c d.
The gas is conducted through the horizontal tube / g, ter-
minating in a jet-point, where the tache of the flame can be
received upon a clean porcelain surface C. As heat decom-
poses the arseniuretted hydrogen, means are provided to
heat the tube while the gas is passing, the radiant heat
being cut off by a screen c. In this case the metallic arsenic
appears in a ring at /, while the flame loses its peculiar
character, and no tache is seen at g. The ring so obtained
may be subsequently tested as before indicated, as well also
as the tache. The cause of the tache will appear on a
moment's attention. Calling to mind what was said on the
structure of flame, (460,) it is obvious, by reference to fig.
386, showing a larger view
ofthejet£,rfig.385,)that
. the part a' c must contain
- the reduced arsenic in hot
hydrogen gas, surrounded
by the burning envelope
a c b. Now the porcelain
surface is held in the line
Fig. 386.
Describe fig. 385. What does the heat accomplish ? How is the tache
tbtained in fig. 385 ?
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MERCURY. 361
t x, and must receive the metallic mirror, if any arsenic is
present.
614. In most cases of arsenical poisoning it is required
to search for proof in the mass of organic matters ejected by
the patient, or in the tissues of the body itself; and either
case requires all organic matters to be destroyed before tests
can be applied. This may be done in a great majority of
cases by oxydizing and charring the whole mass to be treated,
cut small, in a porcelain capsule, with a mixture of strong
nitric acid and oil of vitriol. These are added in small
quantity, and gentle heat applied until the coaly mass is nearly
dry. Water is then added, and the whole thrown upon a filter
and washed : the filtrate contains all the arsenic and other
metals. Marsh's, Reinsch's, or any of the other tests just
enumerated may then be applied. Such is a very brief ac-
count of the most valuable modes of examination in cases of
poisoning by arsenic. Further details would be out of
place here.
CLASS IV. NOBLE METALS: WHOSE OXYDS ARE RE-
DUCED BY HEAT ALONE.
MERCURY.
Equivalent, 100. Symbol, Hg, (Hydrargyrum?) Density,
13-596.
615. This is the only metal which is fluid at ordinary
temperatures. It is found as native, or running mercury, in
Spain and Carniola, and also as cinnabar, or sulphuret of
mercury. In Upper California a very large deposite of cin-
nabar has lately been opened. It is also found both in Mexico
and Peru. The alchemists supposed it to be silver enchant-
ed, (quicksilver,) and made many efforts to obtain from it
the solid silver it was supposed to contain.
Pure mercury is a silver-white, fluid metal, unchanged by
air, and very brilliant. Cooled below — 3944°, as by car-
bonic acid, (150,) it solidifies, and is then as malleable as
lead. It crystallizes in cubes. It boils at 662°, and forms
a colorless vapor, of the density 6-976. Even at 32°, a
614. How is proof obtained in case of organic matters being present ?
What agent of oxydation is used ? How is the testing carried on ? What
are noble metals? 615. What of mercury? How found? Why called
quicksilver ? What are its propertief ?
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METALLIC ELEMENTS.
very rare vapor rises from it, as is evident from the effect
on daguerrian plates. If heated in the air at or above 600°,
it slowly passes to the condition of red oxyd of mercury,
which is its highest combination with oxygen. By this ex-
periment Lavoisier proved the composition of air, and per-
formed the first recorded chemical analysis.
616. The uses of mercury are numerous and important in
the arts, and also in medicine. It forms alloys (amalgams)
with many other metals ; with tin it constitutes the brilliant
coating of glass mirrors, (called silvering,) and it is of indis-
pensable importance in procuring gold and silver from their
ores, and in gilding by the old process. Its use in filling
thermometers and barometers has already been noticed. It
expands by each degree of Fahr. 2^TTJ of its bulk, in heat-
ing from 32° to 212°, and at nearly the same ratio for the
whole scale of 662°.
617. The purity of mercury is roughly judged of by its
forming no film on glass, and by its breaking into small
globules, which should preserve their spherical form, when
they run from an inclined surface. If they form a queue, or
drag a tail, as the workmen express it, it is owing to the
presence of lead or some other similar impurity.
It may be purified from all non-volatile ingredients by
Fig. 387.
distillation in an iron bottle A, (fig. 387,) formed of one of
the iron flasks in which quicksilver is imported. This is
What of its volatility? 616. What are its uses? What fits it spe-
cially for thermometers ? What is its rate of expansion ? 617. Btow if
Its purity judged of ? How is it purified ? Describe fig. 387.
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MERCURY. 888
completely enclosed in the furnace, and the tnbe b c con-
nects with a bag of leather or caoutchouc, reaching to a basin
of water, and kept cool by a stream of water from the cock
r. The tension of its vapor is very small, so that it quickly
returns to the fluid state, thus producing a great commotion
in the process of boiling. The distilled mercury is only
partly purified, and the process must be completed by the
action of dilute nitric acid at a gentle heat, which unites to
form nitrate of mercury with a part of the mercury. This
salt reacts with the other portion of the mercury to form
nitrates of all other metals which may be present. After a
day or two, with frequent agitation, the action is complete,
the water is evaporated at a gentle heat, and the crust of
nitrate of mercury removed. The remaining mercury, now
quite pure, is washed with much water and dried.
Mercury may be so finely divided by agitation and other
mechanical means, as to lose its metallic appearance entirely,
as in blue pill, mercurialized chalk, (creta cum hydrargyro,)
and mercurial ointment, which do not, as has sometimes
been stated, contain the suboxyd of mercury, but only
mercury in a state of very minute meohanical division.
Nitric acid dissolves mercury very rapidly even in the
cold : hydrochloric acid scarcely acts on it, and sulphurio
only by the aid of heat, when it forms an insoluble sul-
phate of mercury, evolving sulphurous acid. The equiva-
lent of mercury is often stated at 200, on the supposition
that the gray oxyd is the protoxyd ; but this seems to be
more properly considered as a suboxyd, and the real pro-
toxyd as the red oxyd. On this view the equivalent is
stated at 100.
618. The gray, or suboxyd of mercury, HgaO, is formed
by digesting calomel in caustic potash, or by adding the
same reagent to a solution of the nitrate of the suboxyd of
mercury. It is an insoluble, dark gray powder, which is
easily decomposed into metallic mercury and the red oxyd,
Hg90 = HgO+Hg.
The red oxyd, or 'protoxyd, red "precipitate, HgO, is
prepared in the large way by heating the nitrate very cau-
tiously until it is quite decomposed, and a brilliant red
How is the purification completed ? How does mechanical action af-
fect it? Give examples. What dissolves it? How does SO, affect it?
What of its equivalent ? 618. How is suboxyd formed ? How decom-
posed ? How is the red oxyd formed ? What is precipitate per $e t
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864 METALLIC ELEMENTS.
crystalline powder produced. It may also be formed by
heating metallic mercury for a long time in a glass vessel
nearly closed, and in this form is the preparation to which
the old name of red precipitate per se was applied. Heat
decomposes this oxyd, into oxygen and metallic mercury.
It is, like the oxyd of lead, slightly soluble in water, and
gives to it an alkaline reaction. It is a poison, and is used
externally as an irritant and escharotic.
619. The cMorids of mercury correspond to the oxyds,
and are both very important compounds.
1. Subchhrid of Mercury, (Calomel,) Hg3CL— This well-
known medicine is formed by precipitating a solution of sub-
nitrate of mercury with common salt. A white, insoluble, taste-
less powder falls, which is the calomel. Even strong acids,
when cold, do not affect it ; but it is instantly decomposed
by alkalies, and the suboxyd produced. Heat sublimes it
unchanged. Its complete insolubility at once distinguishes
this safe and mild substance from the highly poisonous
corrosive sublimate. It should be in very tine powder for
medical use, as then the presence of corrosive sublimate is
easily detected in it by imparting its taste to water. Its
freedom from adulteration may be determined by heating it
on the surface of a clean spatula, when it should volatilize
unchanged without leaving any residue. It is obtained by
slow sublimation, in beautiful transparent crystals — square
prisms with octahedral summits. Its density is 6*5, and in
vapor 8*2. Vapor of calomel is composed of
1 volume of mercury vapor. 6*976
£ volume of chlorine. 1*220
1 volume of calomel vapor.. Hg*Cl 8*196
Calomel is decomposed by nitric acid, forming corrosive
sublimate and nitrate of protoxyd of mercury. Ammonia
turns it to a gray powder, which is an amid and chlorid of
mercury Hg^Cl.HgNH,.
2. Corrosive Sublimate, or Chlorid of Mercury, HgCl.
— This salt is most economically prepared by the decompo-
sition of sulphate of mercury, by common salt, whose
How does heat affect it ? How is it used ? 619. What of the chlo-
rids? What is the name of the subchlorid ? How formed ? What are its
properties ? What of its state and purity ? Its density ? What is the
constitution of its vapor? What decomposes it ? What is corrosive
t ublimate ?
Digitized
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MERCURY. 365
simple interchange gives corrosive sublimate and sulphate
of soda, HgO.S03+NaGl = HgCl+NaO.S08. The chlo*
rid is also formed by dissolving the red precipitate in hot
chlorohydric acid. Corrosive sublimate is a very heavy
crystalline body, soluble in about 16 parts of cold water,
and in two or three parts of hot, giving a solution which
possesses the most distressing and nauseous metallic taste,
and is a deadly poison. It is soluble in alcohol and ether.
It melts at 509° and sublimes at about 563°. Its vapor
has a density of 9*42, and contains
1 volume of vapor of mercury '.. 6*967
1 volume of chlorine 2*440
1 volume HgCl 9*407
Albumen completely precipitates it, and the whites of
eggs or milk are therefore antidotes for this poison. For the
same reason it is, doubtless, that timber and animal sub-
stances are preserved from decay, as in the hyanizing pro-
cess, by steeping in solution of corrosive sublimate. The
albuminous portions of wood suffer decay sooner than the
vegetable fibre, and these are rendered completely inde-
structible in the process of. Mr. Kyan, which is now in use
in our national shipyards.
Ammonia produces in solution of corrosive sublimate (and
also in those of other salts of protoxyd of mercury) a
white bulky precipitate of uncertain composition, and long
known as white precipitate. It is regarded as a double amid
and chlorid of mercury HgflCl.NHg.
620. There are two iodids of mercury, HgaI and Hgl.
— The second is a brilliant scarlet-red precipitate, formed
by adding solution of iodid of potassium or hydriodic acid
to a solution of corrosive sublimate. The iodid is at first
yellow, but soon passes by molecular change into the splen-
did scarlet crystalline powder before noticed. It cannot be
used as a pigment on account of its instability.
Two stdphurets of mercury exist HggS and HgS, the first
of which is a black powder, formed when sulphuretted hy-
drogen is passed through a solution of subnitrate of mercury.
The sulphuret HgS, or cinnabar, is formed when the nitrate
How procured ? Give the formula. Give its properties. What is the
density of its vapor? What is an antidote for it ? What is kyanizing?
What is white precipitate ? 620. What iodids of mercury are there t
Whatsulphurets?
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866 METALLIC ELEMENTS.
of mercury (nitrate of the red oxyd) is treated with sulphu-
retted hydrogen. It is a black precipitate, but turns red
when sublimed, and forms the familiar pigment, vermillion.
This is the common ore of the quicksilver mines.
Salts of Mercury.
621. The salts of protoxyd of mercury HgO are colorless,
but the basic salts are yellow.
The Nitrates of Mercury. — The action of nitric acid on
mercury varies with the temperature and the strength of the
acid. In the cold, dilute nitrio acid dissolves mercury,
forming a neutral nitrate of the suboxyd ; but if the mercury
is in excess, a salt is deposited in large and transparent white
crystals, which is a nitrate with excess of base. If hot and
strong, the nitrate of the red oxyd is formed, which is a very
soluble salt, not crystallizable. A basic salt of this oxyd
may also be formed, which is decomposed by water.
Sulphate of mercury HgO. SO, results as an insoluble
white subcrystalline powder, by the action of the strong acid
on metallic mercury, sulphurous acid being evolved. Boil-
ing water decomposes this salt, removing a part of its acid,
by which a yellow basic sulphate is formed, known as tur-
peth mineral. Its composition is 3HeO.SOa. The sulphate
of the gray oxyd HgaO.SO, is formed as a crystalline white
powder, by treating a solution of subnitrate of mercury with
sulphuric acid. It is slightly soluble in water. Fulminat-
ing mercury and other cyanids are described in the organic
chemistry.
All the compounds of mercury are volatile at a red heat;
and those which are soluble whiten a slip of clean copper,
by depositing metallic mercury on its surface.
SILVER.
Equivalent, 108. Symbol, Ag. (Argentum.) Density, 10#5.
622. The mines of Mexico and of the Southern Andes
furnish most of the silver of commerce, although many mines
of this metal are found in Spain, Saxony, and the Harts
Mountains. Galena, or the native sulphuret of lead, is also
What is vermilion? 621. How are the nitrates of mercury obtained?
What is the nature of the nitrate of the red oxyd ? How is the sulphate
formed ? What are the characteristics of mercurial compounds ? 622.
From what sources is silver obtained ?
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SILVER. 867
a constant source of silver, as it is never quite free from this
precious metal. Silver is often found native. It is more
usually in combination with sulphur and antimony.
The brilliant lustre and white color of this valuable metal
are familiar to all. It is perfectly ductile and malleable, and
in hardness stands between gold and copper. For the pur-
poses of economy and in coinage it is essential to alloy it
with about T^ part of copper, to render it sufficiently stiff
and hard. It is one of the best conductors of heat and
electricity, and its surface reflects light and heat more per-
fectly than any other metal. It is used for this reason in
reflectors ; and hot fluids longer retain their heat in vessels
of silver than in any other. It remains untarnished in air free
from sulphur gases ; from these it gains a brown-black sur-
face of sulphuret of silver. It does not combine with oxygen
when heated in it ; but fused silver absorbs even twenty times
its volume of oxygen, parting with it again on cooling. It
is slightly volatile even in the furnace, but in the carbon
crucible of the galvanic focus (fig. 169) it volatilizes com-
pletely. It crystallizes in cubes often very beautifully
modified. It fuses at 1873° ; and, owing to its absorption
of oxygen and disposition to contract in the mould, it is a
difficult metal to cast. Nitric acid dissolves silver in the
cold with great rapidity, and if it contains any gold, this is
left undissolved as a brown powder. Solution of coin alloy
appears green, from the copper it contains. Hydrochloric
acid scarcely acts on silver, and sulphuric acid only when
hot, forming the sparingly soluble sulphate.
Silver is obtained pure from its solution in nitrio acid by
precipitation with metallic copper, as a finely-divided crys-
talline powder ; also by decomposing its chlorid by fusion
with two parts of dry carbonate of potash.
623. Silver is parted from alloys of copper and from argen-
tiferous lead by the process of cupellation. This depends on
the oxydation of the base metal in a
current of heated air, and the absorption
of these oxyds by the cupel. This is
made of bone-ashes, and compacted in a
mould into the form of fig. 388 ; seen in Fig. 388.
What are the properties of silver ? What does fused silver absorb ?
How volatile ? What of coin ? What dissolves it ? What separates mo-
tallic silver from its solution ? 623. What is cupellation ? Describe the
cupel.
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868
METALLIC ELEMENTS.
section in fix. 889. The bone-ash does not fuse at the most
intense heat of the cupellation furnace. The
s t*r cupels are of various sizes, according to the weight
wzzzzf of the assay. In metallurgic art they are employed
Fig. 389. in the final purification of silver-lead, of immense
size, constructed on a hearth of bricks. Those here figured
are small, and are heated in a muffle, or low oven-shaped ves-
sel, (fig. 390,) set in the cupellation furnace,
i as shown in section A, (fig. 392.) Several
cupels are accommodated on its hearth,
Fig. 390. while the air entering its mouth D, partly
closed by E, draws over the surface of the fused assay, and
out at the lateral slits A in the muffle, thus oxydizing the
Fig. 391. Fig. 392.
lead. Fig. 391 is a general view of the cupellation furnace,
which is formed of three parts, united where the bands are
shown. The sectional drawing (fig. 392) indicates more
clearly the relations of the parts. Small charcoal is fed to
the fire Gr at F, and the ignited coal finds its way to B, where
it rests on the hearth K. To aid this descent, an iron rod
What is the muffle ? Describe the process and figs. 391 and 392.
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SILVER. 369
is introduced from time to time at o 0, (fig. 391.) The
opening I H regulates the draft, which is suspended by open-
ing F G. The muffle is thus heated very intensely, and the
condition of the assay is observed from time to time by re-
moving E. M is the draft-pipe, and N a sheet-iron shelf to
receive the hot cupels. Pure metallic lead is usually added
to the alloy to be cupelled, to several times its weight. The
oxyd of lead is absorbed as fast as it is formed, carrying
with it oxyd of copper and other impurities into the porous
bone-ash. Finally, at the close of the process, the globule
of silver flashes into a perfectly polished sphere or button
of a white color. This is one of the most ancient and valu-
able of metallurgical operations, and is equally applicable
to gold and its alloys as to silver. By this process all the
currency of the world is regulated, — in connection with the
process of solution in nitric acid, and precipitation by a stand-
ard solution of salt, which is known as Gay-Lussac's wet
assay in distinction from cupellation, which is called the dry
method.
624. Much of the lead of commerce contains too little silver
to allow an economical use of the process of cupellation . The
silver is then separated by Pattinson's process, as it is called,
founded on the fact that the alloy of silver and lead is more
fusiUe than pure lead; and the latter, on cooling, separates
in small crystals, which can be skimmed out of the richer lead
by an iron cullender. This process enables the metallurgist
to remove with profit even so small a proportion as six ounces
of silver from a ton of lead. The small portion of rich lead
is then cupelled.
625. Three oxyds of silver are known by chemists : the
snboxyd Ag90 j the protoxyd AgO; and the peroxyd AgOfl.
We will now notice only the protoxyd. This is formed
when the solution of silver in nitric acid is saturated with
caustic potash, or when the chlorid of silver, recently pre-
cipitated, is digested in a solution of caustic potash of den-
sity 1/3. It is a dark-brown or black powder, if prepared
by the first mode, or quite black and dense by the second
process. It is a base, forming well-defined salts. Ammonia
How does the button appear at the consummation of the process?
What is the wet and what the dry assay ? 624. What is Pattinson's pro-
•oss? 625. What oxyds of silver are there? How is AgO formed?
What are its properties ?
24
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370 METALLIC ELEMENTS.
dissolves it readily, and it is also somewhat soluble in water,
to which it gives an alkaline reaction. The solution of oxyd
of silver in cyanid of potassium forms the silver-plating so*
lution in this branch of electro-plating. The oxyd is easily
reduced by heat alone, and by the contact of organic matter.
626. Chlorid 0/ silver AgOl is formed -when any soluble
salt of silver is treated with a soluble chlorid or with chlo-
rohydric acid. This substance fuses at a moderate red
heat into a transparent pale-yellow fluid, which is horny and
tough when solid, and hence called horn silver, a form in
which this metal is sometimes found in mines. It is very ^
sensitive to light, turning dark and finally black, especially
in contact with organic matter in sunlight. It is easily
reduced to the metallic state by the nascent hydrogen gene-
rated when zinc is acted on by dilute sulphuric acid in con-
tact with the chlorid. Pure silver and chlorid of zinc result ;
or it may be reduced by fusion with twice its weight of car-
bonate of soda or potash, (622.)
The iodid and bromid of silver are, like the chlorid, inso-
luble in water, and very sensitive to light. The daguerreo-
type and calotype are both dependent on the sensitiveness
of these compounds to light, for the accuracy and beauty
of their results.
The sulphurets of silver are found native, and the tarnish
which blackens silver articles on long exposure, is formed
by sulphuretted hydrogen in the air.
627. The nitrate 0/ silver AgO.N05 is a salt which crys-
tallizes in beautiful flattened tables of an hexagonal form,
soluble in half their weight of hot water. By heat it fuses,
and, when cast in cylindrical moulds, forms the slender
sticks called lunar caustic, so much used by the surgeon.
Its solution has a disgusting metallic taste, even when very
dilute. It is a most delicate test of the presence of chlorine
or of any of its compounds. It blackens rapidly in contact
with organic matter when exposed to the light, and forms
an indelible ink, which is much used in marking linen.
Solution of cyanid of potassium will remove the stain pro-
duced by nitrate of silver. Metallic copper at once throws
down metallic silver from the nitrate, and solution of nitrate
626. Describe the chlorid. How can it be reduced? What are the
relations of the silver compounds to light? What is the action of sul-
phuretted hydrogen on silver ? 627. Describe the nitrate. What is lunar
caustic ? What are its reactions ?
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GOLD. 37i
of copper is formed. Mercury precipitates metallic silver
from * dilute solution, in beautiful tree-like forms, called
cvrbor Diance. Ammonia, by acting on precipitated oxyd
of silver, forms a fulminating compound. It is extremely
hazardous to deal with, as it explodes even when wet.
The fulminating silver produced by the reaction of alco-
hol, nitric acid, and silver, will be described in the Organic
Chemistry.
GOLD.
Equivalent, 98'7. Symbol, Au. Density, 19-26.
628. This valuable metal is found only in the metallic or
native state, being very widely diffused in small quantities
in the older rocks. From these, by the action of various
causes, it finds its way into the sand of rivers, and is dis-
tributed in small quantities, in many widespread deposits
of coarse gravel or shingle, as in Alta California, Australia,
on the eastern flanks of the Ural mountains, and over a wide
belt of country in Virginia, the Carolinas, Georgia, and Ala-
bama. These diluvial deposits furnish nearly all the gold
of commerce, by the process of washing and amalgamation
with mercury. Large masses of gold sometimes occur, as
one of twenty-eight pounds in North Carolina. In Si-
beria a mass was found, now in the Imperial Cabinet of St.
Petersburg, weighing nearly eighty English pounds. Several
of still greater • size, mingled with quartz, have been found
in California. Generally, however, it occurs only in minute
rounded and flattened grains or scales. It is also found in
veins of quartz, in compact limestone, and distributed in
iron pyrites. Native gold is usually alloyed with from 5
to 15 per cent, of silver. Since the discovery of gold in
California, in March 1847, it is estimated that at least fifty
millions of dollars have been annually obtained there, chiefly
from the auriferous sands of those regions.
629. Gold is distinguished by its splendid yellow color,
its brilliancy, and freedom from oxidation, by its extreme
malleability and ductility, by its high specific gravity, (19-26
to 19*5,) and by its indifference to nearly all reagents. It
What is the arbor Diance t 628. How does gold occur in nature ? How
ii il obtained? What of California? 629. Describe this metal ?
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872 METALLIC ELEMENTS.
fuses at 2016° F., and is dissolved only by aqua regia,
(420,) chlorine, nascent cyanogen, and by selenic acid. The
first is the solvent commonly known, and yields perchlorid
of gold.
630. Gold forms two very unstable oiyds, AuaO and
AutO,, which are decomposed even by light. Two corre-
sponding chlorids exist. The perchlorid is a very deliques-
cent salt, forming a red crystalline mass, soluble in ether,
alcohol, and water. Metallic gold is deposited in elegant
crystalline crusts from the ethereal solution of the cblorid.
Ammonia throws down from solutions of gold an olive-
brown powder, fulminating gold, which, when dry, explodes
with heat, or by percussion.
631. The solution of protosulphate of iron throws down
gold from its solutions in a very fine brown powder, which,
wben diffused in water, is green, as seen by transmitted light.
The protochlorid of tin forms a characteristic purple preci-
pitate in gold solution, called the purple of Cassius, whicb
is used in porcelain-painting, and is probably a compound
of the oxyds of tin and gold. Gilding of ornamental work
is usually performed by gold-leaf; but other metals are
gilded, either by applying it as an amalgam with mercury,
the mercury being afterward expelled by heat, or preferably
by the new process of galvanic gilding from a solution of the
double cyanid of gold and potassium. Gold wash, as it is
called, is applied by a mixture of carbonate of soda or potash
in excess, with oxyd of gold, in which small articles cleansed
in nitric acid are boiled, and thus become perfectly covered
with a very thin film of gold.
632. Palladium, Pd. — This very rare metal is usually as-
sociated with gold, being found in a native alloy of gold and
silver from Brazil. It is a white metal, more brilliant than
platinum, very infusible, malleable, and ductile. It is, how-
ever, fused by the compound blowpipe. It gains a blue
tarnish, like steel, by heating in the air, which it loses by a
white heat. In hardness it is equal to fine steel, and it does
not lose its elasticity and stiffness by a red heat. Its density
varies from 10*5 to 11-8. It suffers no change by exposure
What is its usual solvent ? 630. How many oxyds of gold are there f
Describe the perchlorid. 631. What tests distinguish gold? How if
gilding effected ? 632. What of palladium ? What peculiar properties
Us it?
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PLATINUM. 373
in tbe air. It gives a peculiar and beautiful color to tbe
surface of brass wben applied in tbe electro-metallurgical
process. Its equivalent is 53-3. Its qualities would
render it a very valuable metal if it could be obtained in a
sufficient quantity. Nitric acid dissolves it slowly, but aqua
regia more rapidly. It forms two oxyds and two correspond-
ing cblorids.
PLATINUM.
Equivalent, 98*7. Symbol, PL Density, 19*70 to 21-23.
633. Platinum Is ai very remarkable metal, and, if abun-
dant, would be extensively useful in domestic economy. It
' is found native in tbe gold-workings in Soutb America, and
in Siberia on the eastern slope of the Urals. No ore of
platinum is known except its alloy with gold, and those
with iridium, osmium, and rhodium.
Platinum is a white metal, between tin and steel in color,
but harder than gold or silver, and, unless quite pure, is,
when unannealed, nearly as hard as palladium. A very
little rhodium or iridium renders it more gray in color and
much harder. If pure it is very malleable, especially when
hot, and can then be imperfectly welded. Its ductility and
tenacity are remarkable ; but its most valuable property is
its infusibility, which is so great that the thinnest platinum
foil may be safely exposed to the most intense heat of a
wind furnace. It is soluble only by aqua regia. It alloys
readily with lead, iron, and other base metals, so that great
care is needed in using platinum vessels, not to heat them in
contact with any metal or metallic oxyd with which they
combine. Caustic potash, and phosphoric acid, in contact with
carbon, will also act upon platinum at a red heat. This
is a most useful metal to the chemist, and vessels of plati-
num are quite indispensable in the operations of analysis.
Large retorts or boilers are made of it for the use of manu-
facturers of sulphuric acid, holding sometimes sixty or
more gallons. In Russia it has been employed in coinage,
for which by its great density and hardness it is well suited.
When recently fused by the compound blowpipe or the gal-
633. What is the history of platinum ? Describe its characters and
uses ? What of its density ?
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874
METALLIC ELEMENT8.
vanic focus, its density is about 19 -9, which is increased to
21*5 by pressure and heat.
634. Platinum is obtained pure by digesting crude plati-
num in aqua regia, and adding to the deep-
brown liquid a solution of chlorid of ammo-
nium : this throws down an orange-colored
precipitate, which is a double chlorid of plati-
num and ammonium. This precipitate is
reduced by heat to the metallic state, — a
porous dull-brown mass, commonly known as
platinum sponge. All the platinum of com-
merce is treated in this way. The sponge is
condensed in steel moulds, like fig. 393, by heat
and pressure, and when compact enough to bear
the blows of the hammer, is heated and forged
until it is perfectly tough and homogeneous.
The follower K is driven down by the hammer
upon the platinum sponge confined in the steel
seat c b.
I Spongy platinum is a very remarkable sub-
'* stance, having, as already noticed, (409,) power
Fig. 393. tQ cause the combination of hydrogen and
oxygen, and to effect other chemical changes without being
itself altered.
Platinum black is a still more curious form of this metal.
It is formed by electrolyzing a weak solution of chlorid of
platinum, when the black powder appears on the negative
electrode. The silver plates in Smee's battery (192) are
prepared in this way. It is also prepared by adding an
excess of carbonate of soda, with sugar, to a solution of
chlorid of platinum, and gradually heating the mixture to
near 212°, stirring it meanwhile. The black powder which
falls is afterward collected and dried. This powder has
the property of causing union among gaseous bodies — as,
for example, the elements of water — to a greater degree
than the spongy platinum.
635. Platinum forms two oxyds, and two chlorids, vis.
PIO; P10a and P1C1; P1C1,. The oxyds are prepared from
the chlorids by precipitation with alkalies, and are very
634. How is it obtained from its ores ? How is it condensed ? What
Is platinum black, and what are its properties ? 635. How is tho bi-
ehlorid prepared ?
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osmium. 376
unstable. The protochlorid is prepared by heating the
bichlorid to 460°, when chlorine is evolved and P1C1 is
left as a greenish-gray insoluble powder.
The bichlorid of platinum is the usual soluble form of
platinum, and is always formed when platinum is digested
in aqua regia. It is prepared pure by dissolving spongy
platinum in this menstruum, and cautiously expelling the
acid by evaporation, at the temperature of a water-bath. It
gives a rich orange colored solution both in alcohol and water;
and forms insoluble salts of much interest, with many metallic
chlorids. Those with the alkaline metals are the most im-
portant. The double chlorid of platinum and potassium is
a very sparingly soluble salt, (PlClaKCl,) which falls as a
yellow, highly-crystalline precipitate, when chlorid of plati-
num is added to a solution of chlorid of potassium. The
double chlorid of sodium and platinum (PlClgNaCl+GHO)
is, on the other hand, very soluble, and forms large beautiful
yellowish-red crystals in a dense solution. Potash and
soda are most easily separated, by the different solubility of
their double platino-chlorids. The double chlorid of am-
monium and platinum (PlClaNH4Cl) is the orange precipi-
tate before named, and is the best test to determine the
presence of platinum in a solution.
Associated with platinum are iridium, osmium, rhodium,
and ruthenium — metals whose rarity permits us to pass them
with a very brief mention.
636. Iridium (Eq. 99) is found alloyed with osmium,
forming the mineral iridosmine, IrOs„ in flat scales, mal-
leable with difficulty. It is the hardest alloy known,
being as hard as quartz. It is very infusible. It is true tin-
white, crystallizes in hexagonal forms, and its density is from
19*3 to 2112 being the densest body known. This mineral
is much used to point gold pens. It is unacted on by aqua
regia. It forms four oxyds.
Osmium (Eq. 99*6) has a density of 10, of a bluish-white
color, is neither fusible nor volatile, and forms, by its com-
bustion in air, the very volatile and poisonous osmic acid
0s4. It forms five oxyds, OsO, Os,08, Os,0, Os80, and Os40.
Fused with nitre, osmium forms osmiate of potassa.
Describe the double chlorids of platinum and the alkalies, their prepa-
tion and characteristics. What metals are associated with platinum f
636. What of iridium ? What use has iridosmine ? What is the density
of iridium? What of osmium? Its oxyds?
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876 METALLIC ELEMENT8.
Rhodium (Eq. 52*2) is so named from the rose color of its
salts. It is a reddish-white metal, density about 10*5, and
resembles iridium in hardness, fusibility, and malleability,
as well as in resisting the action of acids. It forms two
oxyds, RhO and Rha08.
Ruthenium (Eq. 52*2) is another metal obserred lately,
to the extent of 5 or 6 per cent., in the iridosmine. Its den*
sity is ahout 8*6. It is very like iridium in all its charac-
ters, and has until lately been confounded with it
What of rhodium? Its color and density? Its oxyds? What ©I
nthenu* m ? Where found ? What relations has it ?
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877
PART IV.— ORGANIC CHEMISTKT.
[Thi last edition of this work was written about five years since, and
having been desired to prepare this portion of the book for a new edition,
it was thought proper to re-write it almost entirely. The views of chemical
theory here adopted, have been in part advanced in the pages of the "Ame-
rican Journal of Science" during the last four years. I have there at-
tempted to point out what I conceive to be true in the respective systems
of Giessen and Montpellier; and have laid down certain principles, which,
in the present work, have been applied to the elucidation of a variety
of questions. I have refrained from here developing at full length my
own theoretical views, as being from their novelty unsuited to the cha-
racter of an elementary treatise.
It has been my plan to select from the great amount of matter which
the chemistry of the carbon series now embraces, those subjects whose his-
tory is well known and best fitted to illustrate the theory of the science,
and at the same time to include the matters most interesting, in a practical
view, to the medical and general student Both these classes will, how-
ever, find it necessary to resort to more extended works for the history
of many series of compounds, which have been omitted or very briefly
noticed in these pages; while, on the other hand, it is hoped that the more
advanced student will not find tho work unworthy of a perusal.
I have not thought it necessary in an elementary treatise to cite
authorities; but I may remark that I have availed myself of the works
of Liebig, Gerhardt, and Gregory, and of the various chemical memoirs
which have appeared in the different scientific periodicals for the last few
yean. The most recent discoveries in organic chemistry are here em-
bodied.
T. STERRY HUNT.
Mohtkbal, Canada East, July, 1852.]
INTRODUCTION.
Nature of Organic Bodies.
637. Definition. — The name of Organic Chemistry is used
to designate that branch of the science which investigates the
phenomena and results of organic life, examines the che-
mical relations of animals and plants, and the properties and
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878 OEQANIC CHEMISTRY.
transformations of the peculiar bodies which they afford.
The constituents of organic bodies are comparatively few in
number. Carbon with oxygen, hydrogen, and nitrogen,
form all the combinations peculiar to organic substances.
In addition to these, however, sulphur, phosphorus, and
iron sometimes occur in small quantities in organio products;
and the results of their decompositions and transforma-
tions under the influence of different reagents, give rise to
an immense number of compounds, in which, with the four
organic elements already mentioned, are often united sul-
phur, phosphorus, arsenic, antimony, chlorine, bromine,
iodine, and the metals.
638. It was formerly supposed that the production of the
so-called organic substances was exclusively the prerogative
of life. But later discoveries have shown that it is possible
so to combine the organic elements as to form many of the
products which were formerly obtained only through the
medium of plants and animals. Hence the distinction be-
tween organic and inorganic chemistry is no longer so well
defined as before. But as in organic bodies carbon is always
present, and is the only constant element, we may define or-
ganic chemistry as the chemistry of the compounds of carbon.
We may distinguish in mineral chemistry many such classes
of compounds; as the nitrogen series, in which nitrogen is a
constant and characteristic element; the silicon series, in-
cluding all the silicious compounds: so in studying the
chemistry of organic bodies, we find that they may all be re-
duced to one, tlie carbon series.
639. Among the organic matters which make up the
structure of living beings, we must distinguish two classes :
first, organized substances, which show either to the naked
eye, or under the microscope, a peculiar structure, entirely
different from that of crystallization, and never exhibited
except in those matters which have been formed under the
influence of the vital force : such are the woody and muscular
fibres, the cellular and vascular tissues, the globules of
blood and of starch (which see). These are not always
homogeneous chemical compounds, and art, even could it
imitate their chemical constitution, will never succeed in
giving them their organized forms. The power which effects
this must ever remain one of the secrets of life.
The second class of organic substances includes those
which are either produced by the destruction of organized
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LAWS OF CHEMICAL TRANSFORMATIONS. 879
bodies, or are the secretions or excretions of organized
beings. They are subject to the same laws of form as in-
organic bodies, and are liquid, solid, or gaseous, crystallized
or amorphous. It is this second class of organic substances
which we are able to form artificially, and which are pro-
perly in the domain of the chemist ; among these are in-
cluded the various alcohols, oils, acids, resins, sugars, gums,
alkaloids, and coloring matters.
640. The immediate effect of chemical agencies upon or-
ganized bodies is to produce disorganization, and to convert
them into substances which belong to the second class.
Hence the study of organized structures belongs to the phy-
siologist, and it is only where he leaves them that the
chemist begins. The effect of strong heat upon organic
bodies is peculiar. They are completely decomposed into
a variety of products, among which are water, carbonic acid
gas, carburets of hydrogen, and, if nitrogen be present, am-
monia. The carbon, which is generally present in larger
quantity than is required to form- these compounds, remains
in the form of charcoal; hence organic bodies are always
more or less combustible, and, unless volatile,. generally char
or blacken by heat.
641. In addition to the bodies of the carbon series, both
animals and vegetables contain salts of potash, soda, lime,
magnesia, and iron, with sulphuric, phosphoric, and silicic
acids, chlorine and fluorine. Animals also secrete phosphate
and carbonate of lime to form their bones, as in vertebrates,
' and their external coverings, as in the mollusca. These salts
have been already described under their proper heads, in
the Inorganic Chemistry, and their relations to life will be
considered in the section on the nutrition of animals and
nlants.
Laws of Chemical Transformations.
642. The various changes met with in the study of or-
ganic substances, resulting in the destruction of existing
combinations, and the formation of new ones, may conve-
niently be reduced to two classes ; first, equivalent substitu-
tions, and second, direct union. It will oe shown that, in
the first case, decomposition and recomposition are reciprocal
and simultaneous, so that the one implies the other, and we
investigate at once the laws of both. In the second case,
this relation apparently does not exist ; but there is a direct
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880 ORGANIC CHEMISTRY.
decomposition which is the converse of direct union, and
consists in the partition or dissection of a compound into
two or more compounds having a lower equivalent.
Equivalent Substitution.
648. The law of substitution is, that one or more atoms
of an element in a compound may be replaced by any other
element, or group of elements, which are equivalent in their
chemical relations; and the chemical constitution of the
compound remain unchanged. Thus acetic acid C4H404
may lose three atoms of hydrogen and take in their place
three equivalents of chlorine, which last are substituted for
the hydrogen, without changing the acid constitution of the
body j the new compound, chlorqcetic acid, C/HC13)04
closely resembles acetic acid in its properties. Here 35*5
parts of chlorine are equivalent to 1 of hydrogen, and Cl3 is
equivalent to H3, and may be substituted for it without
altering the type of the compound. Bromine and iodine,
and perhaps fluorine, may replace hydrogen in a similar
manner.
644. In the foregoing reaction C4H404 and Clfl are con-
cerned, and C^HCl^O, and 3(C1H) are the results. We
shall show farther on, from a consideration of their combining
volumes, that as the equivalent volume of chlorohydric acid
is (HC1), that of hydrogen is (HH), and that of chlorine
(C1C1). In the reaction between acetic acid and chlorine,
there are then but three equivalents or volumes of chlo-
rine, 3(C1C1), and each successive volume exchanges one*
of its atoms for one of hydrogen: thus, (C4H404)-f-(ClCl)
=(C4H3C104)+(CIH)— and so on with a second and third
volume of chlorine. In many instances we can trace the
successive steps by which atom after atom of hydrogen is
replaced by chlorine, a corresponding equivalent of hydro-
chloric acid being simultaneously formed. The law of equi-
valent substitution is then reducible to that which has
been called double elective affinity, and always supposes the
reaction of two complex bodies, which give rise to two new
ones.
645. As hydrogen is replaceable by CI, Br, and I, so
oxygen is caf>able of being replaced by sulphur, selenium,
and tellurium. This can seldom be effected directly, as in
the case of chlorine and hydrogen, but it is obtained by in-
direct decompositions. Alcohol, which is Gfifi^ gives suU
Digitized by VjOOQ iC
EQUIVALENT SUBSTITUTION. 381
pkur alcohol, C4H8S3, and the selenium compound will bo
C4H6Se3. Mineral chemistry affords similar instances;
sulphate of soda is 2SOg-f-2NaO, or S3Na308, while the hypo-
sulphite of soda is SjjNa3(03S6), and another salt is S^a,
(04S4). These different sulphates crystallize with the same
amount of water, have the same form, and the same solu-
bility.
Nitrogen, phosphorus, arsenic, and antimony, which form
a natural group, may also replace each other, equivalent for
equivalent ; thus, glycocoll, which is C4H5N04, has a corre-
sponding arsenical conipouud, alkargene, C4H5As04.
646. When any acid, like chlorohydric or acetic acid, acta
upon a metal such as zinc, hydrogen is evolved, and a chlo-
rid or acetate of zinc is formed, in which Zn has replaced
the hydrogen, HCl+Zn=H+ZnCl, and C4H404-f-Zn=
C4H8Zn04-f-H. If chlorine (C1C1) acts upon zinc, we ob-
tain the same chlorid as with chlorohydric acid, (ClCl)-f-Znf
=2(ZnCl), and when chlorine combines with hydrogen, it is
(ClCl)+(HH)=2(HCi). Now as the action of HC1 upon zinc
evolves hydrogen (HH), all these analogies lead us to conclude
that the equivalent of zinc is Zn3=(ZnZn), and hence that
in the case of acetic or chlorohydric acids, an equivalent of
zinc reacts with two equivalents of the acid. Acetic acid
C4H404+ZnZn=C4(H3Zn)04+(ZnH), but ZnH with an-
other equivalent of C4H404 yields a second equivalent of
acetate and one of hydrogen (HH). The hydrates of metals
like ZnH are seldom stable, and as they decompose water
,and acids very readily, are difficult to be isolated. The re-
placement of the hydrogen in acids by a metal is then ana-
logous to that of its substitution by chlorine.
647. When an acid is brought in contact with a metallic
oxyd, double decomposition ensues in the same manner,
but with the formation of an oxyd of hydrogen ; acetic acid
C4H404+ZnO=C4H8Zn04-f HO. But with the equiva-
lents here proposed, the composition of oxyd of zinc must
be written Zn302, and that of water H303, so that as in
the reaction with metallic zinc, two equivalents of the
acetic acid react with Zn303. If we represent the actions
as consecutive, the first result will be (ZnH)03, or the
hydrated oxyd of zinc, corresponding to ZuH, which with
another equivalent of acid exchanges its Zn for H, forming
water, (Ha03).
648. All the metals proper are capable of replacing in this
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882 ORGANIC CHEMISTRY.
manner a portion of the hydrogen of acids to form salts.
A great number, like acetic acid, have only one atom of
hydrogen which can be replaced by a metal, bnt in others
two and three atoms may be in a similar manner replaced.
These are called bibasic and tribasic acids; while such as
acetic acid are said to be monobasic. Tartaric acid is bibasic;
its composition is represented C8H9018, or C8H4(H8)018j
the two equivalents of hydrogen may be replaced by two
equivalents of some metal as CsH4Zn90ia; by two dif-
ferent metals as in CsH4(KNa)018, or but one equivalent
may be replaced as in C8H4(HK)018. The latter still
retains acid properties, and is called an acid salt The salts
of tribasic acids may contain either one, two, or three equiva-
lents of hydrogen replaced by a metal; the first two of
these salts will be acid, and the last neutral.
The monobasic acids are almost always volatile, while
the bibasic and tribasic acids are never volatile without
decomposition.
649. The sesquioxyds, which have been represented in
treating of mineral chemistry as composed of two equivalents
of a metal combined with three of oxygen, offer a peculiar
case in the formation of salts. If we take, for example, the
peroxyd of iron, Fes08, we find that it saturates, not twe
equivalents of acetic acid, but three, and that while in the
acetate of the protoxyd of iron FeO replaces H, in the acetate
of the peroxyd two- thirds of an equivalent of iron sustain the
same relation ; if then we would represent the acetate of the
peroxyd, we must write it C4H8Fe|04. In other words
FeflOa has reacted as if it were 3(FeJO). But if we ex-
amine these two salts still farther, we find that in their che-
mical reactions they differ from each other as widely as the
salts of two distinct metals, and that we have in the salts of
the peroxyd, iron with two-thirds its ordinary equivalent, and
with peculiar and distinct properties. We may designate
the iron in the proto-salts hs/errosum, with an atomic weight
of 28 and the symbol Fe, and the iron in the persalts as
ferricum, with an atomic weight of 18*6, and write its
symbol, fe. The sesquioxyd of iron, Fea08, is then 3(feO)
and the corresponding acetate of ferricum 04H8feO4.
This same view is to be extended to the proto and ses
qui-salts of chromium and manganese, and to the salts of
alumina, which is a sesquioxyd ; also to the salts of mercury
and of tin, in which the equivalents of the two forms are to
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EQUIVALENT SUBSTITUTION. 383
each other as 1 : 2. We have ckromosum and chromicum,
aluminicum, stannosum and stannicum, mercurosum and
mercuricum; the second form of the metal is distinguished
hy writing its symbol with a smaty letter as Cr, cr, al, Sn,
«*; Hg, hg, &c.
650. We have seen that acetic aojd may exchange three
equivalents of hydrogen for chlorine, and but one equiva-
lent for a metal, so that in chloracetate of silver, C4C1, Ag04,
all the hydrogen is replaced. There are many acids in
which we cannot effect the substitution by chlorine, nor can
the fourth atom of hydrogen in acetic aoid be thus replaced;
it can be removed only by substituting a metal. Thus the
hydrogen which is replaceable by chlorine is distinct from
that which is equivalent to a metal. It will be shown far-
ther on, however, that there are some bodies in which this
distinction appears to be lost, and in which all the hydrogen
may be replaced either by chlorine or a metal.
651. In treating of the action of chlorine upon acetic
acid, we have considered the process only with reference to
the acid ; but the substitution is reciprocal, and there is
mutual decomposition. To make the question more simple,
we will select a case where but one atom of hydrogen is
replaced. The essence of bitter almonds, benzoilol, has the
composition C^HgOj, ; by the action of chlorine, hydrochlo-
ric acid is formed, and one atom of hydrogen is replaced by
chlorine, C14H60fl+(ClCl)=C14H5C10fl+H CI. Now if we
consider only the oil, it will be said that an equivalent
substitution has taken place of CI for H ; but it is equally
correct to say, that the benzoilol minus H has replaced CI in
the equivalent of chlorine (C1C1) ; in other words, that the
essence has ceded H to form hydrochloric with CI, and that
the residue has replaced the eliminated atom of chlorine.
When the constitution of the bodies becomes more com-
plex, the action is still the same ; benzoilol reacts with nitric
acid, which is NH08, and yields water and a new substance
containing the elements of the essence and the acid, minus an
equivalent of water; C14H6Ofl+NHO0=C14H5NOfl+HaO9.
An examination of this reaction leads to the conclusion
that the acid has furnished H and the essence HOa to
form the equivalent of water ; so that the residues C14Hfc
and N06 unite to form the new product; and it may be
said that C14H5 replaces H in the nitric acid, precisely as
C14H40a replaces CI in the equivalent of chlorine.
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8tf4 ORGANIC CHEMISTRY.
652. The monobasic nitric acid has fixed the element*
of a neutral body in place of its atom of hydrogen, and
the nitrobenzoilol is hence neutral. But if benzoic acid,
which is monobasic, be substituted for the essence, it pre-
serves even in combination its saline character; and hence the
compound has the monobasic character which pertains to the
benzoic acid. And even if this nitrobenzoic compound re-
places the hydrogen of a second atom of nitric acid, the mono-
basic character is still preserved in the resulting compound.
A bibasic acid, like the sulphuric, will form with one equiva-
lent of a neutral substance a monobasic acid; and with two,
a body which shall itself be neutral ; because in these cases,
one and two atoms of hydrogen have been removed from the
acid. But if an equivalent of a monobasic acid reacts with
sulphuric acid, it still retains its saline power in combina-
tion, and the result is bibasic : in like manner, with another
bibasic acid, sulphuric acid yields a compound which is triba-
sic. In all these reactions, as io the formation of nitroben-
zoilol, corresponding equivalents of H909 are eliminated, and
the derived bodies are often designated as coupled acids.
653. Some writers have distinguished these cases from the
simpler instances of equivalent substitution, and have desig-
nated them as substitutions by residues. But this distinction
originates in a too much restricted idea of the meaning of
an equivalent. In an early period of the science, the
equivalent of a metal was fixed from the proportion of hydro-
gen it replaces, or in other words from the composition of
its salts; but we have since learned that although 28 parts
of manganese are generally equivalent to 1 of hydrogen and
35-5 of chlorine, there are cases where, as in permanganic
acid, which corresponds to perchloric acid, 56 parts of
manganese are equivalent to 35*5 of chlorine; and in the
sesqui-salts of the metal, 18 6 of manganese become equiva-
lent to H; so 31-7 parts of copper are at one time equiva-
lent to one of hydrogen, and 63*4 parts at another time.
Hence the numbers assigned as the equivalents of the
elements are changeable as these elements change theif
functions, and, as in the case of benzoilol, groups of carbon
and hydrogen, or carbon, hydrogen, and oxygen, may become
equivalent to a single atom of chlorine of hydrogen or a
metal, and may replace it in combination.
These groups which replace the metals on the one hand,
and chlorine and bromine on the other, have been described
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EQUIVALENT SUBSTITUTION. 885 .
by some authors by the name of compound radicals, and
have served as the basis of a system of organie chemistry
and of nomenclature. But as we conceive that the system
is liable to great objections, and tends to perpetuate false
notions of the science, the language of the compound radi-
cal theory will not be employed in these pages.
654. The law of direct union is much more simple. A
salt may assimilate the elements of water, or of a metallic
oxyd, or ammonia may combine with an acid, as with hydro-
chloric acid, to form sal-ammoniac; NH8-r-H01=NH4Cl.
A carbon compound, like olefiant gas, C^H^ may also
unite directly with Cl3, to form C4H4C18. In these and
similar instances there is only one product, a character by
which such reactions are distinguished from those of the
first class. On the other hand, a body may eliminate the
elements of water or of hydrogen, or some similar sub-
stance, and thus resolve itself into two ; for instance, alcohol
C4Hfl0fl, under the influence of certain reagents, may lose
H8, and in some of its combinations is resolved by heat
into C4H4, and Hfl09. Many ammoniacal salts which are
formed by direct union of the acid and ammonia, separate
under the influence of heat into water, and new compounds
called amids, which, when placed in contact with water,
under proper conditions, combine with that substance, and
regenerate the original salts.
655. The compounds formed by direct union may then
divide in a manner different from that of their composition,
and thus produce two new compounds unlike the parent
ones, precisely as in the reactions of the first class. We
hence arrive at the conclusion, that the phenomena of the
second class represent only an intermediate step in the pro-
cess of equivalent substitution ; and that if we could arrest
the latter process, we should always find it to consist of two
parts, composition and decomposition, resulting in a mutual
substitution. As an illustration, may be cited the com-
pound formed by the direct combination of chlorine with
olefiant gas, which is C4H4Cla, but under certain circum-
stances is decomposed into HC1 and C4HSC1 ; the latter is a
substitution product from olefiant gas, and we are here enabled
to see the intermediate step in its formation.
The two classes into which we have for convenience di-
vided the phenomena of chemical transformations, are then
reducible to one simple formula; a+6 and c-\-d may unite
25
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,386 ORGANIC CHEMISTRY.
to form a-\-b-\-c-\-dy and may afterward be rearranged so as
to form a-\-c and o-f-e?, as in the first, or a-\~b and c-f-d, as in
the second case.
On Combinations by Volumes.
656. The law of combination by volumes has already
been given in the first portion of this work (257) ; but we
refer to it again to explain the density of vapours, and the
equivalents of organic substances.
The proportions in which oxygen and hydrogen unite to
form water are one volume of the former to two volumes
of the latter, and these three are condensed into two volumes
of the vapor of water at 212° F. As these proportions have
been assumed to correspond to one equivalent of each, the
composition of water is written HO, having an equivalent
number of 1+8=9, and corresponding to two volumes of
vapor.
The specific gravity of hydrogen has been found by experi-
ment to be 69-2, air being 1000, while oxygen is 1105*6.
Then
2 volumes of hydrogen 2 X 60*2.. 138*4
1 M of oxygen 1105-6
yield 2 volumes of vapor water. 1244*0
1 " of do. do 6220
Experiment gives for the density of water vapor 620*1.
657- Density of Carbon Vapor. — In calculating the atomic
volume of bodies of the carbon series, it becomes necessary
to fix upon the density of carbon vapor; but as carbon is
not known in a gaseous form, we must deduce its density
from that of some one of its compounds.
When carbon is burned in oxygen gas, this is converted
into carbonic acid gas without change of volume. If we
subtract from the weight of the new compound that of the
oxygen, we shall then have the weight corresponding to the
caibon vapor. Experiment has given for the density of
Carbonio acid gas (air = 1000) 1529*0
Deduct that of oxygen 1105*6
Gives for the density of carbon vapor 423*4
If we suppose the gas to consist of two volumes of carbon
vapor and two of oxygen condensed one-half, the equivalent
volume of carbon will be the same as that of hydrogen, and
its weight represented by the above number. But if it
may, with as good reason, be regarded as formed by the con
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DIVISIBILITY OP FORMULAS. 387
densation of two volumes of oxygen and one of carbon vapor
into two volumes, the density of carbon vapor will be twice
the number calculated, or 846 8.
The experimental density of carbonic acid is, however,
not very exact, and the density of carbon vapor may be
more accurately calculated from the well-determined density
of oxygen. Carbonic acid consists of oxygen 72*73 and
carbon 27*27 parts, and the observed density of oxygen is
1105*6; we have then this proportion:
72-73 : 27-27 : : 1105-6 :x.
in which x = 829, which we shall adopt as the most correct
number for the density of carbon vapor.
658. Hence, if we know the composition and equivalent
of any body, we can calculate its density ; or, having the
density and composition given, can fix its equivalent. For
example, the density of defiant gas, as found by experiment,
is 9674. It consists of equal equivalents of carbon and hy-
drogen, and one volume of it contains
2 volumes of hydrogen = 1 eq. 2x69-2 138-4
1 " of carbon vapor = 1 eq .829-0
Yield 1 volume of olefiant gas 967*4
If now the equivalent of olefiant gas be like that of water
represented by two volumes, the formula will be CaH3; but
most writers have assumed four volumes as representing the
equivalent of organic compounds; while water is written HO,
and corresponds to but two volumes of vapor. Thus the
the formula of olefiant gas is generally written C4H4 = four
volumes of vapor ; to be compared with this, water must be
HflOfl. Some of the French chemists, choosing to preserve
the old equivalents of organic bodies, have doubled in this
manner that of water; while others have preferred to divide
the formulas of organic substances, and reduce all to the
standard of two volumes, oxygen being one; or, in other
words, to take the volume of the atom of hydrogen as unity.
We shall in these pages regard Ha, which is equivalent to
four volumes, (0 being one volume,) as unity, and write the
formula of water HaOa, with an equivalent of 18.
On the Law of the Divisibility of Formulas.
659. The researches of Gerhardt and Laurent have esta-
blished a very important law which prevails in the grouping of
elements in compounds, not only in those of the carbon series.
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388 ORGANIC CHEMISTRY.
bat also in mineral chemistry. It is, that in all compounds
of carbon, hydrogen, and oxygen, represented by an equiva-
lent of four volumes of vapor, the number of atoms of carbon
and oxygen is always divisible by two, and that of the atoms
of hydrogen by the same number. If the oxygen is wholly
or in part replaced by sulphur or selenium, the substitution
is always atom for atom, so that the same divisibility is
maintained; and if the hydrogen is replaced in whole or in
part by chlorine, iodine, or bromine, by nitrogen, phospho-
rus, arsenic, or antimony, or by any of the metals, the sum
of the number of the atoms will always be a multiple of two*
On Isomerism.
660. We have seen, in treating of substitution, that a num-
ber of the atoms of any element in a compound may be re*
placed by another element, and the constitution of the body
remain unchanged. From this, and from other facts, we con*
elude that the properties of compounds depend rather upon the
peculiar arrangement, than upon the species of their consti-
tuent atoms; and, moreover, that a different arrangement of
the same elements may form compounds very different in
their properties. Such bodies are frequently met with among
the carbon series, and are denominated isomeric compounds,
(from isos, equal, and meros, measure.) We have an instance
in the essence of spiraea ulmaria, and benzoic acid, both of
which are represented by the formula C^HgC^, but are very
distinct in their characters. The relation of such as have
not only the same proportional, but the same actual com*
position, may be distinguished by the term metamerism,
(from metaf by, and meros, measure.)
Another form of isomerism is that in which the relative
proportions of the elements being the same, the equivalent
of the one is a multiple of the other. Thus, defiant gas
C4H4, butyrene CSH8, naphtene C16Hl6, and cetene C^B.^
have the same proportions of carbon and hydrogen, though
each has a density and equivalent double that of the pre-
ceding; such bodies are said to be polymeric, (from polus,
many, and meros.)
The phenomena which in mineral chemistry have been
characterized under the names of dimorphism and aUotiro*
pism are instances of isomerism which is often polymeric, and
are met with even among bodies which are considered as
elementary.
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CHEMICAL HOMOLOGUES. 389
On Chemical Bbmologues.
661. The carbo-hydrogens just mentioned, whose com-
position is represented by a multiple of C4H4, are possessed
of similar chemical affinities, and form with other substances
similar compounds. Two of them, the first and last, are arti-
ficially formed from compounds which have the formula
C4H60aand C^H^O,,, and differ from their respective hydro-
oarbons only by the elements of water.
These compounds are two terms of a series of bodies which
are known as alcoJwls, from common alcohol, which was the
first known of the series. The first one has the formula
CaH40a=CaHa-fHa0a, and the next C4H6Oa, each one dif-
fering from the last by CaHa; so that representing by n any
number divisible by two, the general formula of the series
will be CmHn+HaOa, or C^H^C^. Bodies thus related
are designated komohgues; and the study of this relation-
ship, which was first pointed out by Gerhardt, is of the high-
est importance to the science.
The bodies of an homologous series generally undergo simi-
lar changes by like reagents, and the products resulting are
also homologous. Thus, wine alcohol , by oxydizing agencies,
loses Hj, and forms the body C4H40a; by further oxydation
it yields acetic acid C4H404; and every alcohol in like man-
ner yields an acid homologous with the acetic acid : the ge-
neral formula of the series being CllHn04. The intermediate
body C^B^Oj, has not, however, in all cases been obtained.
The alcohols also yield a series of homologous alkaloids,
whose common formula is (C^H^HgN or C.H^gN.
662. In many homologous series the number of equiva-
lents of hydrogen is not equal to that of the carbon, and
the formula must be written differently. Thus, benzoic acid
C14H604 and cuminic acid CaoHia04 are homologous, and
diner from each other by (CaHa)3, and we may express
them by the general formula C„H1l_804, the number of equi-
valents of hydrogen being less by eight than that of carbon :
by this it will be seen that the lowest term of the series will
be that in which n — 8 =2, or C10Ha04; for if n — 8 =zero,
the compound will contain no hydrogen, and hence want the
^characteristic properties of an acid which belong to the series,
*If, however, the hydrogen be present in excess, the case will
be different. In the formula of the alcohols, if n = zero, the
representative of the type, is H^O^ or water, which is the
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890 ORGANIC CHEMISTRY.
prototype of the alcohol series ; and in the alkaloids of th<s
same group, when n=zerof we have NHS, or ammonia, which
is equally their prototype.
It will be seen from what we have said of isomeric bodies
that there may be two or more series of homologous bodies,
which shall be metameric of one another, and hence simi-
larity of chemical characteristics is necessary to constitute a
homology. In an homologous series of chemically allied
compounds, then, while the oxygen and nitrogen always
remain the same, the proportions of hydrogen and carbon
vary by a simple and constant ratio.
Temperature of Ebullition.
663. A simple relation between the boiling points of
different members of an homologous series has been pointed
out, which may often serve an important end in deciding the
equivalent of a compound. The boiling point of the volatile
acids of the formula CJEI.C^ is found to increase about
86° F. for each addition of CaHa.
ANALYSIS OE ORGANIC SUBSTANCES.
664. The ultimate analysis of organic substances is of
great importance : for as we are unable to form them by a
direct combination of their elements, a correct understanding
of their composition, and of the nature of the changes which
they undergo, must depend entirely on the results of their
analysis. The equivalent of many substances is so large,
that a change of one-hundredth part in the proportions, gives
to the compound entirely distinct properties. Great refine-
ment is consequently necessary in analysis, to enable us to
detect the minute differences in composition ; and such have
been the care and skill with which the subject has been
studied, that we have now arrived at very great accuracy
in operations of this kind.
665. In theory, the process of organic analysis is ex-
ceedingly simple. If any organic substance, as sugar, for
example, is heated with a body capable of yielding oxygen,
such as the oxyd of copper, of lead, or any other easily re-
ducible metal, it is completely decomposed ; the carbon and
hydrogen take oxygen from the metallic oxyd, and are wholly
converted into carbonic acid and water. From the weight
of these, it is easy to calculate the amount of carbon and
hydrogen in tne body, and if it contains no other element
Digitized by VjOOQ IC
ANALYSIS Or ORGANIC SUBSTANCES. 391
except oxygen, this is known by the loss. But notwith-
standing the theoretical simplicity of the process, its accurate
execution is exceedingly difficult, and very many precautions
are necessary to insure accuracy. It is not the object of this
work to explain all the precautions necessary to the successful
performance of analytical operations, but merely to give an
outline of the method pursued, and a general idea of the means
employed. For more particular information, the student is
referred to an excellent memoir on this subject, by Liebig.
666. The operation is performed in a combustion tube of
hard glass, from 12 to 18 inches in length, and from T40 to T59
of an inch in diameter. One end is drawn out to a point,
turned aside and sealed. Oxyd of copper, prepared from
the nitrate, is generally employed for the combustion.
Just before using it, it is heated to redness, in order to expel
the moisture which it readily attracts from the atmosphere ;
the combustion tube is then about two-thirds filled with the
hot oxyd. The substance to be analyzed having been care-
V
'Oxyd. Mixture. Oxyd.
Fig. 394.
fully dried, five or six grains of it are weighed out in a tube
with a narrow mouth, in order to prevent the absorption of
moisture. It is then rapidly mixed in a warm and dry por-
celain mortar, with the greater portion of the oxyd from the
tube, to which it is again transferred, and the tube is then
nearly filled up with pure oxyd. The relative portions of
the oxyd and mixture are shown in fig. 394.
667. However carefully the mixture has been made, a
little moisture will have been absorbed from the air, which
must be removed by the following arrangement : — To the
end of the combustion tube is fitted, by means of a cork, a
long tube filled with chlorid of calcium, and to this is at-
tached a small air-pump, fig. 395. The combustion tube is
covered with hot sand, and the air slowly exhausted. After
a short time, the stopcock is opened, and the air allowed to
enter, thoroughly dried by its passage over the chlorid of
calcium. It is again exhausted, and this process repeated
four or five times, by which the mixture is completely dried.
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&92
ORGANIC CHEMISTRY.
Fig. 395.
668. The tube is now ready for the combustion, and is
placed in the
furnace, figure
396. This is
constructed of
sheet iron, and
*»g.3fle. fitted with a
series of supporters at short distances from each other, to
prevent the tube from bending when softened by heat. The
furnace is placed on a flat stone, or tile, with the front
slightly inclined downward. The quantity of water form-
ed in the process is estimated by a light tube, fig. 397,
which is filled with frag-
SfTPfhwiiifffi^==a meDts of chlorid of calcium,
Fig. 397. aQd> *£ter having been very
carefully weighed, is attach-
ed by a well-dried and closely fitting cork, to the end of
the combustion tube. To determine the carbonic acid, a
small five-bulbed tube of peculiar form is used, called Liebig's
potash bulb tube, fig. 398. It is charged for
this purpose with a solution of caustic potash of
a specific gravity about 1*25, with which the
three lower bulbs are nearly filled. Its weight
is determined with great exactness, and it is
then attached to the chlorid of calcium tube,
by a little tube of gum elastic, which is held
fast by a silken cord. The whole arrange-
ment is shown in fig. 399. The tightness of
Fig. 398. the junction is ascertained by drawing a few
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ANALYSIS OF OEQAKJO SUBSTANCES. 393
Fig. 399.
bubbles of air through the end of the potash tube, so that the
liquid will be raised a few inches above the level on the
other side ; if this level remains the same for some minutes,
the whole apparatus is tight.
669. Heat is now applied by means of ignited charcoal
placed around the anterior portion of the tube, and when
this is red-hot, the fire is gradually extended along the tube,
by means of a movable screen, represented in the figure.
This must be done so slowly as to keep a moderate and uni-
form flow of gas through the potash solution. When the
whole tube is ignited, and gas no longer escapes, the closed
end of the combustion tube is broken off, and a little air
drawn through the apparatus to remove all the remaining
products of combustion. The tubes are then detached, and
from the increase of weight in the chlorid of calcium tube,
the amount of water, and thence that of hydrogen, is deduced.
The carbon is determined from the increase in weight of the
potash bulb tube, by a simple calculation.
670. Volatile liquids are analyzed by enclosing them
in a narrow-necked bulb of thin glass. The weight of the
empty tube is first ascertained ; the liquid is introduced,
the neck sealed, the weight being again ascertained, and
the difference gives the weight of the
substance. The neck of the bulb is
then broken by a file mark at a, ('fig.
400,) dropped into the closed end of
the combustion tube, and covered with
oxyd of copper, which should nearly fill
the tube. When this is heated to red-
ness, a gentle heat applied to the por- (<
tion of the combustion tube containing ii
the volatile fluid, sends it in vapor over
the ignited oxyd, completely burning it. Flg# 400#
The products of its combustion are estimated as before.
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894 ORGANIC CHXMI8TRT.
671. Fatty bodies, and others which contain much carbon
and a small quantity of hydrogen, arc more perfectly burned
by employing chromate of lead instead of copper. This sub-
stance does not readily attract moisture from the atmosphere,
like oxyd of copper, and is consequently better when the hy-
drogen is to be determined accurately. The chromate of lead
is prepared for use by heating it until it begins to fuse, and
when cool reducing it to powder.
672. When nitrogen is a constituent of organic bodies,
it is determined by placing in one end of the combustion
tube about three inches of carbonate of copper, secured in
its place by a plug of asbestus ; and then the nitrogenous
body is introduced, mixed with oxyd of copper. The re-
maining space in the combustion tube is filled with turnings
of metallic copper. The air is then withdrawn by an air-
pump, and a gentle heat applied to the carbonate of copper,
which evolves carbonic acid, and drives out all remaining
traces of common air. The tube is now heated as usual,
and the gases evolved are collected in a graduated air-jar,
over mercury. When the combustion is finished, heat is
again applied to the carbonate of copper, and another portion
of carbonic acid expelled, which drives out all the nitrogen
from the tube. The use of the copper turnings is to decom-
pose any traces of nitric oxyd which may be formed in the
process. The carbonic acid is removed from the air-jar by
a strong solution of potash, and pure nitrogen remains,
which is measured with the usual precautions, and from its
volume the weight is easily determined.
673. Another and a preferable mode of determining nitro-
gen, is that of Will and Varrentrapp, which is founded on the
Fact that when a body containing nitrogen is heated with an
excess of caustic potash, or soda, all the nitrogen is evolved
in the form of ammonia, and may be thus estimated, by con-
ducting it into hydrochloric acid, and forming, with chlorid
of platinum, the double chlorid of platinum and ammonium.
674. Chlorine is determined in the analysis of organic
compounds, by passing the vapor over quicklime heated to
redness in a combustion tube ; chlorid of calcium is formed,
which is afterward dissolved in water, and the chlorine
precipitated by nitrate of silver. From the weight of the
chlorid of silver, the amount of chlorine is calculated.
675. Sulphur is a rare constitutent of organic compounds.
Its presence is detected by fusion with nitre and carbonate
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DENSITY OF VAPORS,
395
ef soda, or by digestion with nitric acid. Sulphuric acid is
thus formed, and is precipitated as sulphate of baryta, from
the weight of which that of the sulphur is determined. In
the analysis with oxyd of copper, a small tube of peroxyd
of lead is introduced between the chlorid of calcium tube
wd the potash apparatus, to absorb the sulphurous acid
which is evolved.
Density of Vapors.
676. The determination of the destiny of vapors is of
great importance ; in the case of some volatile organic com-
pounds which form no combinations with other substances, it
is the only means of ascertaining their constitution and equi-
valent. The process is very simple, and the method employed
in the case of gases has been already described, (49.) When
the substance is a liquid or solid, it is introduced into a narrow-
necked glass globe, of the form represented in fig. 401, the
weight of which is carefully ascertained. The
globe is held by means of a handle firmly
attached by a wire, beneath the surface of an
oil or water-bath, and then heated to some
degrees above the boiling-point of the sub-
stance. When this is all volatilized and the
globe is filled with the vapor, the open and
projecting end of the globe's neck is sealed
by the flame of a spirit-lamp : at the same
time the temperature of the bath is noted.
When the globe is cooled it is again weighed,
and the end of the neck broken off beneath
the surface of mercury, which rushes up and
fills the empty vessel. The mercury is then
carefully measured. The capacity of the
vessel and its weight being thus ascertained, we can find
the weight of a volume of vapor at the observed tempera-
ture, and by an easy calculation can determine what would
be its volume at the ordinary temperature, (88:) its weight
compared with that of the same volume of air gives the
specific gravity required.
677. It is proposed, before commencing the study of those
bodies of the carbon series which we have included under
the head of Organic Chemistry, to consider briefly the prin-
cipal products of the ultimate decomposition of this class
of substances. These are water, ammonia, and carbonic
Fig. 401.
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896 ORGANIC CHEMISTRY.
acid gas. The latter only strictly comes within our limits,
and all of them have been described in the first part of this
work ; but we shall bring them np again to illustrate certain
laws of substitution, which will help to explain the history
of tho more complex organic compounds.
We shall then treat of starch and sugar, and some other
bodies of high equivalents, whose history is comparatively
simple, and proceed to the products of their decomposition
by fermentation and other means, among which are different
alcohols and acids.
Water.
678. In the first part of this volume, water has been de-
scribed as having the formula HO, and as composed of two
volumes of hydrogen and one of oxygen, condensed into two
volumes of vapor of water ; we have already given the rea-
sons which lead us to adopt four volumes as its equivalent,
and to write its formula Hs09.
We shall now speak of the products of substitution de-
rived from water. If the oxygen be replaced by sulphur
we have sulphuretted hydrogen: the selenium and tellu-
rium compounds have a similar composition. One or both
atoms of the hydrogen may be replaced by a metal. Hy-
drate of potash KO.HO is water in which one equivalent
of H is replaced by potassium : it is (KH)09, and anhy*
drous potash will be KflOa. The hydrated oxyds result from
the replacement of one equivalent of hydrogen by a metal,
while in the anhydrous oxyds both are thus replaced.
Water thus resembles a bibasic acid, and the hydrated
oxyds may be compared to acid salts, while the anhydrous
oxyds are like neutral salts.
679. The so-called suboxyds are illustrations of the
change of equivalent upon which we have insisted. The
red oxyd of copper is CusO, or rather 0u4Os, but copper
here unites in twice its ordinary equivalent weight, and in
this form, which we may designate as cuprosum, with the
symbol cu, is strictly equivalent to H and to Cu, so that tho
red oxyd is cuaOfl. The peroxyds, like those of hydrogen
or barium, may be either oxyds which have combined with
an additional amount of oxygen, and thus increased their
equivalent weight, being H204 and BasO*, or tbey may be
regarded as sustaining to the ordinary oxyds the same re-
lation that the black oxyd of copper does to the red oxyd,
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AMMONIA. 897
being compounds in which barium and hydrogen nnite in
one-half their ordinary equivalent : thus, (Ba$)aOfl, &c. The
same views apply to the persulphuret of hydrogen and
Other persulphurets. From the volumes of the correspond-
ing bodies of the carbon series, the first view is probably the
true one.
680. We have shown that in the group H3, chlorine may
replace H to form chlorohydric acid, and we may here refer
to an example in which an atom of the hydrogen is replaced
by a metal. It is a product of the action of hypo-phosphorous
acid upon a salt of copper, and is a yellow powder contain-
ing CugH, which corresponds to euH. Chlorohydric acid
dissolves it with the evolution of hydrogen and the forma-
tion of a chlorid of cuprosum, cuH+HCl=cuCl+HH,
the hydrogen of both being evolved.
It has already been remarked that there are examples of
bodies in which all of the hydrogen may be replaced either
by chlorine or by a metal, and water is such a body; hydrated
hypochlorous acid CIO, HO is (C1H)0S, or water in which
CI replaces H : the second equivalent of hydrogen may be
replaced by a metal to form a hypochlorite, as in CIO.KO,
which is (C1K)03. But this second equivalent may also be
replaced by chlorine, and we have the so-called anhydrous
hypochlorous acid, which is ClsOfl, or water in which chlo-
rine has been substituted for the whole of the hydrogen.
Ammonia^
681. Ammonia is composed of six volumes of hydrogen
and two of nitrogen (0 being represented by one volume,)
condensed to one-half, or to four volumes : its formula is
then NHa. Its properties have already been described, and
we have only to notice some of its derivatives. Like water,
the whole of its hydrogen may be replaced either by chlo-
rine or by a metal. The direct action of chlorine decom-
poses it; the hydrogen forms hydrochloric acid, and the
nitrogen is set free in the form of gas ; but with a solution
of a salt of ammonia, like the muriate or sal-ammonia, the
action is different; the chlorine is slowly absorbed and a
heavy yellow oil separates, which is a most dangerous com-
pound, exploding with great violence by a gentle heat, by
the contact- of phosphorus, fat oils, and many other sub-
stances. It is composed of NC18, and by the explosion is
resolved into these elements. The name of chlorid ofnitro.
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898 ORGANIC CHEMISTRY.
gen has been given to it, but it is ammonia in which the
hydrogen has been replaced by chlorine, and may be called
trichloric ammonia. The action of iodine upon ammonia is
more moderate than that of chlorine : if it is triturated with
a solution of ammonia or mixed in an alcoholic solution, a
black powder is obtained which explodes when dry by the
slightest friction, but less violently than the chlorid. Its
composition is NIaH, and it is therefore biniodic ammonia.
The chlorine compound is indifferent to acids, but the
iodic species still exhibits feebly basic properties: it is
dissolved by dilute acids and precipitated again by a solu-
tion of potash.
682. When potassium is heated in ammoniacal gas, one
equivalent of hydrogen is displaced, and an olive-green com-
pound is obtained, which is N(HaK), and is decomposed by
water into hydrate of potash and ammonia N(HaK)+HaOa
■=(HK)Ofl-f-NH8. When ammonia is passed over heated
oxyd of copper, water is formed, and a compound which con-
tains CugN. It corresponds to the red oxyd of copper, or oxyd
of cuprosum cu90g, and is Ncus, or ammonia in which all the
hydrogen has been replaced by cuprosum. It is formed at
a temperature of 480° F., and is decomposed into its ele-
ments with evolution of light at 540° F.
683. The salts of ammonia next, claim our notice. Their
characters and preparation, and the theory of ammonium
have already been described, (518.) The mode of their
formation is different from that of ordinary salts of metals :
these, we have shown, whether the metals or their oxyds
are employed, are produced by an equivalent substitution
with the elimination of hydrogen or water, while ammonia
and the acids unite directly to form salts, without the pro-
duction of any second body. Thus ammonia and chlo-
rohydric acid NH8-fHCl yield sal-ammoniac NH4G1;
and sulphuric acid, which is bibasic and must be written
2S03.HaOa=SflHa08, fixes directly 2NH3 to form sulphate
of ammonia. But these salts, notwithstanding their differ-
ent mode of formation, are closely analogous to the salts
of potassium and even isomorphous with them ; and while
chlorid of potassium is KC1, the NH4 in sal-ammoniac is
perfectly similar in its relations to K ; and hence sal-ammo-
niac is often regarded, not as the hydrochlorate. of ammonia
NII8.IIC1, but as the chlorid of a quasi-metal} ammonium,
which unites with 01 like potassium, and, like this metal,
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AMMONIA. 390
may even form an amalgam with mercury ; for (NH4)Hg
evidently corresponds to KHg, and ZnHg. Ammonium, NH4,
is then a group which, although it cannot be isolated, may
replace hydrogen, and is equivalent to it. The neutral
sulphate of ammonia is Sa(NH4)3Os, as sulphate of potash is
Sa(Ka)08, and the acid sulphate Sa(H.NH4)08, corresponding
to Sa(HK)08. The group NH4 may be represented by the
symbol Am.
684. The compound corresponding to a metallic oxyd in
which NH4 replaces H, like (KH)Oa, probably exists in the
aqueous solution of ammonia : it will be (NH4. H)Oa or
(AmH)Oa; but the ammonia is readily evolved by heat, the
compound being like some salts of ammonia, very unstable.
We shall see hereafter that there are homologues of ammo-
nia which form more fixed combinations. A compound of
(NHJgOa, or An^O^ corresponding to an anhydrous oxyd,
is also possible ; like oxyd of zinc, (ZnaOa,) it would evolve
an equivalent of water in combining with an acid.
685. In the same way that ammonia combines directly
with acids it may unite with metallic salts ; for example,
with chlorid of copper CuCl+NH8=(NH8Cu)Cl, and
with sulphate of silver SaAga08+2NHs=Sa(NH8Ag)a08:
in these compounds one equivalent of hydrogen in the
ammonia is replaced by copper and silver, and the groups
may be designated cuprammonium and argentammontum.
The white precipitate of mercury obtained by adding am-
monia to a solution of chlorid of mercury is a body of this
class, and is represented by (NHaHga)Cl : when this is
boiled in a solution of sal-ammoniac, another compound is
obtained, which is (NHsHg)Cl. Here one and two equiva-
lents of hydrogen are replaced by mercury.
With the chlorid of platinum a similar chlorid is obtain-
ed, which is known as the green salt of Magnus, and is
(NH8Pt)Cl. But the group NH4 may replace an equivalent
of H in the last, and we have a salt described by Gros and
Keiset, which is N(AmHaPt)Cl or (NaH8Pt)Cl. Still another
one has an equivalent of hydrogen replaced by CI, and is
(NaH6ClPt)Cl. All of these correspond to chlorid of ammo-
nium, and it will be observed that the sum of their atoms
is always divisible by two. They combine with the oxygen
acids like ammonia, and their sulphates, when decomposed b^
baryta, give the hydrated oxyds corresponding to (KH)Otf
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400 ORGANIC CHEMISTRY.
and, like it, caustic and alkaline. Cobalt and some other
metals yields analogous compounds.
686. The decomposition of ammoniacal salts to form water
and am ids has already been alluded to, (654.) An ammo-
niacal salt eliminates one equivalent of water for each equi-
valent of ammonia which it contains, and the salt, if neutral,
yields a neutral amid ; but if the salt is acid, that is, if a
Dibasic acid has combined with one equivalent of ammonia,
and has still an atom of hydrogen replaceable by a metal,
this is preserved in the amid, which is then a monobasic acid.
These compounds are often directly formed by the action of
heat upon the several salts, and sometimes by distilling
them with anhydrous phosphoric acid, which combines with
the water. Amids may sometimes lose the elements of
another equivalent of water, and form a class of bodies
known as anhydrid amids, or nitryh. Acetate of ammonia
C4H404+NH8=C4H7N04— H90a=C4H5N0fl, or acetamid,
from which if HaOa be again abstracted; there remains
acetonitryl C4H8N.
687. Nitrous oxyd, which is NO, or rather NaOa, is formed
from nitrate of ammonia NHOe.NH3, by the abstraction of
2HaOa, and is a true nitryl. Like all the other bodies of this
class, it can reassume the elements of water and regenerate
the acid and ammonia ; when passed over heated hydrate of
potash, a nitrate is formed, ammonia escaping.
Phosphoric acid forms not less than three anhydrid amids,
corresponding to different salts of the different modifications
of the acid. They are all white insoluble powders, which,
under the influence of strong acids or alkalies, yield phos-
phoric acid and ammonia. The one corresponding to nitrous
oxyd is (PN)Oa=P05.NH40-2HaOa.
The points of interest with regard to the amids of the
organic acids will be considered in their proper places.
Carbonic Acid.
688. This compound has already been described, but we
again refer to it to speak of its equivalent, which, to corre-
spond to those adopted for organic substances, must be writ-
ten Ca04 in its anhydrous state. The gas fixes HaOa when
it takes the acid form ; and carbonic acid, such as it exists
in solution, is consequently CaHa06, in which one or both
equivalents of hydrogen may be replaced by a metal, form-
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SUGAR, STARCH, ETC. 401
ing neutral and acid carbonates, or bicarbonates, as they are
often called. .
Carbonic acid is very readily separated from its aqueous
solution, or decomposed into carbonic acid gas and water, in
which it differs from more fixed bibasic acids, which some*
times require a high temperature to effect such a division.
689. Carbonic oxydy which we write Cfl02, is interesting
from its action with chlorine in the formation of phosgene
gas. It directly fixes 2C1 to form CaClaOa, which evidently
corresponds to an hydrogen compound C9HaO. This group,
Df which phosgene is the chlorinized species, is the prototype
of an important class of organic compounds, the aldehydes
C.H.O,
r
SUGAR, STARCH, AND ALLIED SUBSTANCES.
690. Under this head is included a class of substances of
vegetable origin, which agree in containing carbon with oxy-
gen and hydrogen in the proportions which form water.
When soluble, they are insipid, or have a sweet taste, and
are generally nutritious. They are not volatile, and are
readily decomposed by heat and many other agents.
691. Sugars. — These bodies are soluble in water, have *
sweet taste, and most of them by the process of fermentation
yield alcohol and carbonic acid.
Cane Sugar , C^H^O^. — This occurs in the juices of
many plants, as the sugar-cane, maple, beet-root, and Indian
corn. It is obtained by evaporating the juice to a syrup,
when the sugar crystallizes in grains of a brownish color,
and is rendered pure and white by redissolving it, and filter-
ing the solution through animal charcoal, (337.) By the
slow evaporation of a concentrated solution, it is obtained
in fine transparent crystals, which are derived from an oblique
rhombic prism ; in this state it constitutes rock-candy. It
fuses at 356°, and forms, on cooling, a vitreous mass well
known as barley sugar : this gradually becomes opaque and
ehanges into a mass of small crystals of ordinary sugar.
Sugar is soluble in about one-third its weight of water, form-
ing a thick syrup. It is insoluble in pure alcohol.
692. Grape Sugar; Glucose, C^H^O^ + 2H9Ofl.— This
sugar is found in the grape and many other fruits, and in
honey. It is formed when cane sugar or starch is boiled with
dilute sulphuric acid, and is a product in many other trans-
26
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402 OEGANIC CHIMISTKT.
formations. The urine in the disease called diabetes meUitou
contains a large quantity of grape sugar, which is formed
from the starch and similar substances taken as food.
Grape sugar is generally obtained as a white granular
mass, which requires one and a half parts of cold water to
dissolve it : it is less sweet to the taste than cane sugar, and
about two and a half times as much are required to give an
equal sweetness to the same volume of water. When heated
to 212°, the two equivalents of water are expelled. With
sulphuric acid, grape sugar forms a coupled acid, the sul-
Ehosaoohario. It forms with chlorid of sodium, a crystal-
ne compound, which is C^H^O^.NaCl.HgOj,. The water
is lost by heat If a solution of grape sugar is mixed with
a solution of potash, and then with a little sulphate of copper,
the liquid becomes dark, and soon deposits suboxyd of copper
in the form of a red powder ; cane sugar yields no precipi-
tate until the solution is boiled. This test enables us to detect
the jffitro part of grape sugar in a liquid. Honey is a mix-
ture of crystallizable grape sugar, with an uncrystallizable
syrup identical with it in composition.
693. Sugar of Milk; Lactose, CS4H9?O90+2HilOJl.— This
is found only in the whey of milk, and is obtained by evapo-
rating it, and purifying the product- by crystallization.
Lactose forms semi-transparent prisms, soluble in six parts
of cold water, and two and a half of boiling water ; it is
much less sweet than cane or grape sugar. By a heat of
212° its water is expelled ; when boiled with dilute sulphuric
acid, it combines with the elements of two equivalents of
water, and is converted into grape sugar.
Mannite, C^H^O^. — This substance is not properly a
sugar, as it does not contain oxygen and hydrogen in the
proportions to form water, and is not susceptible of fermenta-
tion. It exists in the juice of celery and many sea- weeds,
and constitutes the principal part of the manna of the shops,
which is the concreted juice of a species of ash-tree. When
this is dissolved in hot alcohol, mannite is deposited on
cooling in delicate silky crystals, which are sweet, and very
soluble in water and alcohol.
Mannite dissolves in a mixture of fuming nitric and sul-
phuric acids, and water precipitates from the mixture a
white matter, insoluble in water, which may be crystallized
by dissolving in hot alcohol. It is formed by the fixation of
the elements of nitric acid and the elimination of those of
Digitized
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VINOUS FERMENTATION. 408
water, and is represented by ClflH8N6038. We may repre-
sent N04 as replacing hydrogen, and designate it by X
The new compound, which is called nitro-mannite, will be
then C^H^NO JeOM = O^Xfi^ This mode of notation
is convenient, but, agreeably to the views laid down in the
introduction, we must suppose successive substitutions, in
the first of which C^H^O^ — HOa replaces H in nitric acid
NH08, yielding N^C^H^O^O,, and H?Oa; this product
then reacts with a new equivalent of nitric acid, and so on.
From the large portion of oxygen which it contains, nitro-
mannite is very combustible, and it explodes spontaneously
when struck with a hammer.
Products of the Decomposition of the Siigars.
694. The Vinous Fermentation. — When the juice of grapes
or other fruits containing sugar is exposed to the air, a pecu-
liar decomposition ensues, in which the sugar is resolved
into carbonic acid gas and alcohol. A solution of pure
sugar is not changed by exposure to the air ; but if there is
added to it a little yeast, or the juice of any fruit in the state
of fermentation, decomposition takes place, and carbonic acid
and alcohol are formed. Many substances besides yeast will
effect this change, as blood, albumen, or flour paste in a state
of decomposition. It appears that the influence of a fer-
ment depends on the condition rather than on the kind of
matter. Any nitrogenized substance capable of undergoing
putrefaction produces the same effect, and we are to attribute
this change in the juice of fruits, to a small portion of albu-
minous matter present. The mode in which these substances
act is not understood, but it is supposed that when in a state
of decomposition, they are able to induce a similar state in
other substances with which they are in contact; the equi-
librium of the atoms in the compound is thus disturbed, and
the elements arrange themselves in new forms.
It is interesting to know that the fermentation
of sugar takes place only in immediate contact
with the ferment. This is readily shown, as in
figure 402, by placing a solution of sugar in the
bottle A, and some beer yeast in the tube
abf the lower end of which is covered with
porous paper. The sugar solution passes
through the paper into the tube, where an
active fermentation is set up with an abundant Fig. 402.
Digitized
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404 ORGANIC CHEMISTRY.
evolution of carbonic acid. Meanwhile no change occurs in
the solution in the bottle, which may be preserved unaltered
for any length of time.
695. The act of fermentation is always accompanied by
the appearance of a peculiar microscopic vegetation, which.
is formed when solutions containing albuminous matters
are abandoned to putrefaction. The solution becomes tur-
bid, and a gray deposit is gradually formed in it, consisting
of ovoidal bodies variously grouped, whose development has
been carefully studied under the microscope. Figures 403
to 407 show the various stages of this fungus growth. The
P%%^
Fig. 403. Fig. 404. Fig. 405. Fig. 406. Fig. 407.
original globule (1) A, fig. 403, in about six hours produces
another, (2,) fig. 404, B, like itself; the two again each
germinate a third, as seen at 3, C and D, fig. 405 ; and in
like manner the germination proceeds, as in E, (4,) fig. 406,
until, in about three days, thirty globules are formed about
the original cell. The development then ceases. The se-
veral globules are coherent, but appear to be distinct and
complete in themselves.
696. The conversion of grape sugar into alcohol and car-
bonic acid is very simple : one equivalent of dry grape sugar
CjJB^O^ divides so as to form four equivalents of alcohol
and four of carbonic acid gas.
4 equivalents of alcohol 4XC4H,0a =» C^H^O,
4 " of carbonic acid gas 4 X C904 — C, O^
1 " of grape sugar = C^H^O^
Grape sugar is the only kind which is capable of this fer-
mentation ; and, although the others readily yield alcohol
and carbonic acid, it is found that the first effect of the fer-
ment is to transform them into grape sugar, by the assimila-
tion of the elements of water.
697. Weak alcoholic liquors often become acid when
exposed to the air, from oxydation of the alcohol and the
formation of acetic acid ; but this acid is sometimes directly
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LACTIC ACID. \C 4<0§ l
formed from the decomposition of the sugar, independent of
the action of the air, and is the cause of the souring of such
wines as contain considerable sugar, but are very weak in
alcohol. If a solution of sugar is mixed with cheese curd
and exposed for some weeks to a temperature of about 68° F.,
the air being excluded, it becomes acid, and a portion of the
sugar is converted into acetic acid C4H404. An equivalent
of grape sugar contains the elements of six equivalents
of this acid. The presence of cheese curd under condi-
tions modified by temperature and the presence of earthy
bases, causes other fermentations and different results. At
a temperature of from 95° to 104° F. the products are
lactic acid C^H^O^, and a viscous substance analogous
in composition to sugar. Such a decomposition takes place
in the juices of beets and carrots at a high temperature, and
has been called the viscous fermentation. Mannite some-
times appears as a secondary product. If carbonate of lime
is added to saturate the lactic acid as soon as formed, the
decomposition proceeds at a lower temperature, and the
lactate of lime is almost the only product. An equivalent
of crape sugar C^H^O^ breaks up into two equivalents of
lactic acid C^H^O^.
698. The action of the curd of milk in a more advanced
state of decomposition gives rise to the vinous fermentation :
milk at the ordinary temperature becomes sour from the
conversion of its sugar into lactic acid, but when kept at
about 100° the grape sugar at first formed is converted into
alcohol and carbonic acid gas. In this way the Tartars pre-
pare a spirit from mare's milk; an elevated temperature
promotes the decomposition of the curd and enables it to
effect this transformation.
699. Lactic Acid, C^H^O^. — This acid may be obtained
from sour milk, but is more easily prepared by the fermenta-
tion of sugar with caseine. Fourteen parts of cane sugar are
dissolved in sixty of water ; to the solution is then added
four parts of the curd from milk, and five parts of chalk to
neutralize the acid as it is formed. This mixture is kept
at a temperature of 80° to 95° F. for eight or ten days, or
until it becomes a crystalline paste of lactate of lime. This
Is pressed in a cloth, dissolved in hot water, and filtered ;
the solution is then concentrated by evaporation. On cool-
ing, it deposits the salt in crystals, which may be purified
by recrystallization. The lactate of lime may be uccom-
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406 ORGANIC CHEMISTRY.
posed by the careful addition of oxalic acid, which precipi-
tates the lime, and the solution of lactic acid thus obtained
is concentrated by evaporation, and purified by solution in
ether. It is a syrupy liquid, of specific gravity 1*215, and
is strongly acid to the taste.
700. When lactic acid is heated to 482°, a white crystal-
line substance sublimes, which is called lactide: it is derived
from the acid by the abstraction of the elements of two equi-
valents of water, and has the formula C^HgOg. It is soluble
in alcohol, but scarcely soluble in water : by long continued
boiling with it, however, it is converted into lactic acid.
This acid is bibasic, and its salts are generally soluble and
crystallizable. The lactate of lime C^H^Ca^O^ crystallizes
in fine prisms, with six equivalents of water. The lactate
of zinc is obtained by decomposing a hot concentrated solu-
tion of lactate of lime by chlorid of zinc : the salt crystallizes
in cooling in beautiful colorless prisms. The lactate of iron
C^H^FegO^ is sparingly soluble in cold water, and may be
prepared by a similar process : it is employed in medicine.
A double lactate of lime and potash, and acid lactates of lime
and baryta have been obtained ; the latter is C^H^BaX)^.
If the crystalline paste of caseine and lactate of lime is kept
for some time at a temperature of about 95°, the salt gradually
redissolves, hydrogen and carbonic acid gases escape, and
when, after a few weeks, this new fermentation has sub-
sided, there remains only a solution of the lime salt of a
new acid, butyric acid, C8Hs04. In this butyric fermentation,
the lactic acid is decomposed into carbonic acid, hydrogen
•and the new acid, ClflHM0ls = 2Ca04 + 2Ha+C8H804.
701. Under certain circumstances not well understood,
there appears as an accessory product to the vinous ferment-
ation, an oily liquid, which is homologous with alcohol and
has been named amylol. It is represented by C^H^O,,, and
is supposed to be formed from sugar by a process which
may be called the amylic fermentation, in which, as in the
butyric, hydrogen and carbonic acid will be disengaged.
The action of dilute nitric acid with cane or grape sugar
yields saccharic acid C^H^O^, which is bibasic : strong
nitric acid converts sugar into oxalic acid, and chromic acid
into formic acid. All of these derivatives will be described in
their proper places.
702. When sugar is added to a concentrated solution of
three times its weight of hydrate of potash, and heated, the
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STARCH. 407
mixture becomes brown, and hydrogen gas is evolved. When
the action ceases and the mass is cooled, dissolved in water*
and distilled with dilute sulphuric acid, it yields formic and
acetic acids, with a new acid, the metaeetonic, which is
obtained as a volatile liquid, with a pungent acid odor. It
is monobasic, and has the formula 08H604.
A mixture of sugar and quicklime, when distilled, affordf
acetone and an oily liquid called metacetone which yields
metaeetonic acid when distilled with a mixture of bichromate
of potash and sulphuric acid. Mannite, starch, and gum
afford the same results with hydrate of potash and lime.
703. Gum, C^HjjoOao.— This substance is best known in
gum arable : the gums which exude from the cherry and
plum, the mucilage of flaxseed, and of many other plants,
are identical with it. Gum is soluble in water, and forms a
viscid solution, from which alcohol precipitates it unchanged.
When boiled with dilute sulphuric acid, it is converted
into grape sugar. With nitric acid, gum and lactose yield
the mucic acid, which distinguishes them from all the other
bodies of this class. The mucic acid is a white crystalline
powder, which is sparingly soluble in water : it is bibasic,
and is represented by the formula C^H^O^. It is conse-
quently metameric with the saccharic acid, although quite
different in its properties.
704. The pectic acid, which is extracted from many
fruits, appears to be nothing but a modified form of gum,
and yields grape sugar with dilute acids. It combines with
lime and some other bases to form compounds, which have
been described as pectates. Both gum and sugar have also
the property of exchanging one or two equivalents of hy-
drogen for lead, barium, or calcium, to form similar com-
binations.
705. Starch, C^H^O^. — This substance exists in a great
variety of vegetables. It is found iu all the cereal grains,
in the roots and tubers of many plants, as the potato, and
in the bark and pith of various trees. It is obtained by
bruising wheat and washing it in cold water, which holds the
starch in suspension, and deposits it on standing. Potatoes
furnish a large portion of starch by a similar process. The
substances known as arrow-root, salep, sago, and tapioca,
are varieties of starch, obtained from different plants, and
sometimes altered by the heat employed in drying.
When examined by the naked eye it is a white shining
Digitized
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408 ORGANIC CHEMISTRY.
powder, but under the micro-
scope is seen to consist of irregu
lar grains, which have a rounded
outline, and are composed of
concentric layers, covered with
I _ an external membrane. The
"cy? diameter of the grains of potato
starch is about 3 fa of an inch.
g^ |^^ ^S^jfflEfr Starch is insoluble in cold
^•rfe • 5$ <^%Rln water, but if the mixture is
Tf f§ ^J^P' heated, the globules swell, burst
Fi 408 their envelopes, and form a
transparent jelly, which is cha-
racterized by producing a deep blue color with a solution
of iodine.
When the solution of starch is mixed with a little acid, or
an infusion of malt, and gently heated, it becomes very fluid,
and is changed into dextrine.* This has the same com-
position as starch, but is very soluble in cold water, and is
not colored blue by iodine. If starch is heated to 300° or
400°, it is rendered soluble in water, and possesses all the
properties of dextrine. In this state it is used in the arts as
a substitute for gum, under the names of British gum and
leiocome. When dextrine is boiled for some time with
dilute sulphuric acid, it is converted into grape sugar. It
has been mentioned that grape sugar is formed in this way
from starch ; but its formation is always preceded by that
of dextrine. One part of starch may be dissolved in foul
parts of water, with about one-twentieth of sulphuric acid,
and the mixture boiled for thirty-six or forty hours. The
liquid is then mixed with chalk to separate the acid, and by
evaporation and cooling affords pure grape sugar. Oxalic
acid may be substituted for the sulphuric, with the same
result. Starch sugar is extensively manufactured in Europe,
and is often used to adulterate cane sugar. In this process
the starch combines with the elements of two equivalents of
water, Ca4H20020+2HaOa=CS4H940,M: the acid is obtained
at the end of the process quite unaltered, and one part of
acid will saccharify one hundred of starch by long continued
boiling. Starch or dextrine unites with sulphuric acid to
* So named, because when a beam of polarized light is passed through
the solution, it causes the plane of polarization to deviate to the right
hand.
Digitized
byGoogk
WOODY FIBRE.
409
form a coupled acid; and it is probable that this is first
formed and then destroyed by boiling : at the moment of
decomposition, the liberated dextrine takes up the elements
of water necessary for the formation of sugar. A small
portion of the coupled acid is always found in the solution.
706. The action of an infusion of malt upon sugar is
peculiar: this substance is prepared from barley, by
moistening the grain with water, and exposing it to a gentle
heat till germination takes place, when it is dried in an oven
at such a temperature as to destroy its vitality. The grain
now contains a portion of starch sugar, and a small portion
of a substance called diastase,* to which its peculiar proper-
ties are due. It is precipitated by alcohol from a concen-
trated infusion of malt, as a white flaky substance, which
contains nitrogen, and is very prone to decomposition. When
a little diastase is added to a mixture of starch and water,
at a temperature of from 130° to 140°, the starch is soon
converted into dextrine, and in a few hours into grape sugar.
The action of an infusion of malt is due solely to the presence
of a minute portion of this substance, one part of which will
convert two thousand parts of starch into sugar. This effect
appears to be due to a peculiar state of the diastase, which is
a portion of the azotized matter of the grain in a modified
form, and is analogous to the ferments, already alluded to.
707. Woody Fibre; Cellulose, C^
is the solid insoluble part of vege-
tables, and remains when water,
alcohol, ether, dilute acids, and al-
kalies have extracted from wood
all its soluble portions. It is
nearly pure in cotton, paper or old
linen. The tissue of vegetables
is formed principally of cellu-
lose. The cellular tissue is seen
almost pure, constituting the cell
walls of young plants. These cells
arc sometimes spherical, or rounded
in form. In other cases the
woody tissue forms oblong cells,
communicating by their extre-ni-
Am,. — This substance
Fig. 409.
♦From the Greek diistemi, to separate, because it separates the
insoluble envelopes of the starch globules.
Digitized
byGoogk
410
ORGANIC CHEMISTRY.
ties, as seen in figure 409, which is a section of aspara*
gas, and also in figure 410, which shows a fibre of flai
much magnified. The cellulose in this form receives
whe name of vascular tissue. In the course of time the walls
of the cells become lined with an incrusting matter, which
grows thicker with the age of the plant, finally leaving
only minute
pores or con-
' duits for the
circulation of
Wg.«o. the sap. This
incrusting matter which forms a part of ordinary wood, is
named lignin. It is chemically different from cellulose,
but has been little studied. Figure 411 shows the structure
of wood as seen in the transverse section of a piece of oak,
under the microscope. The black spaces are the ducts,
for the circulation of the
sap, of which a a a are re-
markable examples. The
white lines mark the outline
and comparative thickness
of the original cells, such as
are seen in the vertical sec-
tion of asparagus, fig. 409.
These have been filled with
lignin, which is more dense
and hard near the centre of
the tree than at the exterior.
The albuminous matters,
Fig. 411. which are the principal
cause of the decay of wood, are also more abundant in the
outer than in the inner cells. The coloring and resinous
matters are deposited with the incrusting material.
Cellulose is identical in composition with starch and dex-
trine, and by the action of strong sulphuric acid is dissolved
and converted into that substance. This experiment is easily
made with unsized paper or cotton : to two parts of this,
one part of the acid is very slowly added, taking care to
prevent an elevation of temperature, which would char the
mixture. In a few hours the whole is converted into a soft
mass, which is soluble in water, and is principally dextrine.
If the mixture is now diluted with water and boiled for three
or four hours, the dextrine is completely converted into
Digitized
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GUN-COTTON. 411
grape sugar, which is obtained by neutralizing the acid with
chalk, and evaporation. By this process paper or rags will
yield more than their weight of crystallizable sugar.
708 The mutual convertibility of these different sub-
stances is interesting in relation to many of the phenomena
of vegetable life. The starch in the germinating seed is
changed by the action of diastase into sugar, in which so-
luble form it seems better fitted for the nourishment of the
embryo plant. In the growth of this, we have an example
of the formation of cellulose from sugar, in which this
substance assumes a structural form under the action of the
vital force. This is a transformation from the unorganized
to the organized, which mere chemical affinity can never
effect.
709. Many unripe fruits, as the apple, contain a large
quantity of starch, but no sugar. After the fruit is fully
grown, the starch gradually disappears, and in its place we
find grape sugar. This change constitutes the ripening of
frnits, and, as is well known, will take place after they
are gathered. In this process we have clearly a conversion
of the starch into sugar, by the agency of the vegetable
acids present in the fruit — a change which is the reverse of
the previous one, and is probably independent of life.
710. Xyloidine, Pyroxyline. — The action of strong nitric
acid upon starch yields a compound very similar to nitro-
mannite, which is insoluble in water and very combustible :
if we represent N04 by X, the formula of this body, to
which the name of xyloidine has been given, will be
CMRs^Kflao=Qa§ELt^fijm. With sugar a similar sub-
stance may be formed.
The action of strong nitric acid, or a mixture of nitric
and sulphuric acids, upon woody fibre, such as paper, cotton,
or sawdust, gives rise to an interesting substance, which has
been named pyroxyline, or gun-cotton, as that form of cellu-
lose yields the purest product. The following is an outline
of the process : — one hundred grains of clean cotton are im-
mersed for five minutes in a mixture of an ounce and a half
of nitric acid of specific gravity 145 to 1-5, with the same
measure of strong sulphuric acid ; it is then removed, care-
fully washed in cold water from every trace of acid, and
dried at a temperature which should not exceed 120°. As
thus prepared, it preserves the form of the cotton unaltered,
but has less strength than the original fibre. Jt inflames
Digitized
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412 OEGANIC CHEMISTRY.
by a very gentle heat : sometimes, under circumstances sot
well understood, it has been observed to take fire at 212° F.
Its combustion is instantaneous, accompanied by an immense
volume of flame, and it leaves not the slightest residue.
When ignited in a confined space it explodes with great
violence: one-tenth of a grain is sufficient to shatter the
strongest glass tube. Its power in propelling balls is about
eight times greater than that of gunpowder; its tremendous
energy depends upon the fact that it is completely resolved,
by its combustion, into aqueous vapor and permanent gases,
which are carbonic ozyd, carbonic acid, and nitrogen. As
these are much less noxious than the gases resulting from
the combustion of gunpowder, the gun-cotton will be found
of great use in mining. Its composition is analogous to
that of nitro-mannite. There appear to be two species, one
of which is soluble in a mixture of alcohol and ether, and
the other insoluble; both are generally present in gun-
cotton. They are substitution products from cellulose, and,
representing N04 by X, the insoluble form is C^H^X^O,^
and the soluble C^H^X^ = C^HJtf.O^. It will be
seen that they are formed from the action of nitric acid with
the elimination of HaO, for each equivalent of the add.
Thus, C^H^+GNHOe = O^HJK.O^+eH.O,.
The ethereal solution dries rapidly and leaves a tenacious
transparent film of pyroxyliue : it is used in surgery for
covering wounds and abraded surfaces from the air, and is
known by the name cf collodion.
Transformation of Woody Fibre.
711. By the action of atmospheric air and moisture, wood
undergoes a slow decay, dependent on the absorption of oxy-
gen, to which Liebig has applied the term eremacausis.*
The carbon is converted into carbonic acid, while the oxygen
and hydrogen of the lignine unite to form water. The re-
sidue is still found to contain oxygen and hydrogen in the
original proportions, but the relative amount of carbon is
continually increasing. For each equivalent of carbonic
acid two of water are evolved. The final result of this pro-
cess is a brown or black residue, which constitutes vegetable
* From erema, slow, and kausis, combustion, a term by which that
chemist denotes those changes which take place in organic bodies from
the gradual action of oxygen.
Digitized
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DESTRUCTIVE DISTILLATION OP WOOD. 413
mould. Different products of this decomposition have been
described under the names of humus, geine, ulmine, hutnic
and ulmic acids.
Nearly all of these bodies contain ammonia, for which
they have a strong affinity : this is in part absorbed from
the air, but the experiments of Mulder seem to show that
they have the power of forming ammonia from the nitrogen
of the atmosphere. Pure humic acid moistened and placed
in a close vessel filled with air, is found after some months
to contain a considerable quantity of ammonia. The hydro-
gen, evolved by a slow decomposition of the water, is brought
into contact with nitrogen under such conditions that they
combine and produce the alkali.
712. The decomposition of wood, when buried in the
ground and excluded from the action of the air, is very dif-
ferent The oxygen which it contains gradually combines
with the carbon to form carbonic acid, and substances are
obtained in which the proportion of carbon and hydrogen
is greater than in the original fibre. Peat, lignite, and bitu-
minous coal are products of this decomposition. The car-
bon and hydrogen in coal combine in various ways, and
often generate vast quantities of gaseous carburets of hydro-
gen, (450.) Anthracite has resulted from the action of heat
on bituminous coal, which has expelled all the volatile in-
gredients, and left a residue of nearly pure carbon.
Destructive Distillation of Wood.
713. The principal products of the decomposition of wood
by heat are carbonic acid gas, water, and gaseous carburets
of hydrogen . With the water are mixed several other bod ies,
among which are acetic acid and pyroxylic spirit, presently
to be described, and a quantity of oily, tar-like substance,
containing several interesting bodies, which we shall mention.
These products are obtained on a large scale by distilling
wood in iron cylinders ; the quantity of acetic acid is so
considerable that the process has become important in the
arts.
Kreasote. — This substance occurs dissolved in the crude
acetic acid from wood, and is separated and purified by
a complicated process. It is a colorless oily fluid, which
boils at 397°, and has a specific gravity of 1037. It has a
peculiar and very persistent odor, resembling that of smoke,
and % powerful burning taste. It is soluble in about 100
Digitized
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414 ORGANIC CHEMISTRY.
parts of water, and the solution possesses powerful antiseptic
qualities. Meat which has been soaked in it is incapable
of putrefaction,* and acquires a delicate flavor of smoke.
The power of wood-smoke to preserve flesh is due to the
presence of kreasote. It is a corrosive poison when taken
in any quantity, but a dilute solution is used medicinally,
both internally and externally, as a styptic and antiseptic.
The composition of kreasote is C14H808. It combines with
the alkalies to form crystalline compounds.
714. Wood4ar contains several carburets of hydrogen, one
of which, called eupion, is an oily, fragrant liquid, of the
specific gravity '655, being the lightest liquid known. Its
formula is, probably, C6H6.
Paraffin. — This is a white crystalline substance, obtained
from the less volatile portions of wood-tar. It crystallizes
in delicate needles, which fuse at 110° ; it is soluble in alco-
hol and ether. Its formula is C^H^. Paraffin is obtained
in large quantities by the dry distillation of beeswax.
715. Coal-tar consists principally of a mixture of various
hydrocarbons; some of these are liquid and very volatile,
constituting what is called gas naphtha. Among the less
volatile products are two solid carburets of hydrogen, naph>
thalen, and paranaphthalen, or anthracen. The first of these
is formed by the decomposition of many organic matters
by heat. Its formula is C^Hg : it is volatile, and forms
beautiful pearly crystals of a fragrant odor. The action of
chlorine, bromine, and nitric acid on naphthalen, gives rise
to a great number of compounds. They are formed by suc-
cessive substitutions of the hydrogen by one or more of these
substances, and many metameric modifications of these bodies
exist. Thus, the bichlorinized naphthalen C^Bed,, occurs
in seven modifications, which are perfectly distinct in their
characters. We are led to suppose that these compounds
owe their different properties to a different arrangement of
their constituent atoms, and it is easy to see that, in this
way, the number of possible combinations will be immense.
More than twenty substances have been described, in which
chlorine is in part substituted for the hydrogen of the naph-
thalen. The final product of the action of chlorine is C^Clg,
being a chlorid of carbon, which preserves the type of naph-
thalen. In addition to these, coal-tar contains a consider.
* Hence the name, from the Greek kreaa, flesh, and aoto, I preserve.
Digitized by VjOOQ IC
ALCOHOLS. 415
able proportion of a body named phenol, and several organic
alkaloids. The watery products of the distillation of coal
hold a large quantity of ammonia in solution, often combined
with hydrosulphuric and hydrocyanic acids.
716. Petroleum. — In many parts of the world an oily
matter exudes from the rocks, or floats on the surface of
springs. The principal sources of this substance are Amiano
in Italy, Ava, and Persia, but it is found in many places in
our own country. The well-known Seneca oil is an instance
of this kind. Petroleum is a variable mixture of several
bodies. By distillation, it yields a colorless liquid, called
naphtha, which is very light, volatile, and combustible. Its
formula is, probably, CiaH10. Naphtha occurs nearly pure
in Italy and Persia, and is used for illumination.
Petroleum contains a variety of other bodies, among which
are paraffin, and several resinous matters, formed, perhaps,
by the oxydation of naphtha. These substances are pro-
bably derived from coal or other matters of vegetable origin.
ALCOHOLS.
717. This series of compounds has already been alluded to
in explaining the principle of homology. The alcohols may
be represented by CnH„4_a0a, n being a number divisible
by two: all of them by oxydizing agents lose Ha and
combine with Ofl to form monobasic acids, whose general
formula is CnHn04. Of these acids we have now nearly a
complete series up to the stearic acid, in which n=38.
But a few of the corresponding alcohols are known ; the
principal are methol CaH40a, wine alcohol C4H8Oa, ami/lie
alcohol oxamyhl C10HiaOa, and cetic alcohol or cetol CgaH^Oj,.
We shall first describe the alcohol of wine, to which we
may conveniently give the name of vinol : it is the best
known and most important of the series, and will serve to
illustrate the history of the others.
Vinol — Common Alcohol, C4H60a.
This substance has long been known under the name
of alcohol, or spirits of wine. We have already explained
the manner in which it is obtained as a result of the fer-
mentation of sugar. The vinous fermentation in the juice of
the grape and -other fruits, in an infusion of malt, or in the
Digitized
byGoogk
416
ORGANIC CHEMISTRY.
syrup of the sugar-cane, always results in the conversion of
the sugar which it contains, into alcohol and carbonic acid
gas. When the fermentation is arrested before all of the
sugar is decomposed, the wine is sweet; if the liquor is
bottled before the action is finished, the excess of carbonic
acid remains in solution, and gives an effervescent and spark-
ling property, as in bottled beer and champagne.
When these fermented liquors are distilled, the alcohol,
boiling at a lower temperature than water, passes over
first. By repeated distillation in this way, a liquid is
Obtained which contains 85 parts of alcohol in 100. To
obtain it free from water, it is digested with quicklime, or
better with fused chlorid of calcium, which combines with
the water. The mixture is then distilled in a water-bath,
and pure alcohol passes over. A convenient apparatus for
condensing the vapor of alcohol, ethers, and other volatile
substances, is shown in figure 412. - /
Fig. 412.
The retort r is connected with a glass condensing tube t,
about which a metallic tube m is secured by corks at the ends,
leaving a water-tight space between the two. A funnel tube
/ conducts cold water from the tank w to the lower end of
the condenser. This escapes at the upper orifice o, thus
maintaining a constant current of cold water, by means of
which the vapors of even very volatile liquids are easily
condensed.
718. Pure or absolute alcohol is a colorless fluid, with a
specific gravity of about -800, and boils at 173° F. Its den-
Digitized
byGoogk
ACTION OP ACIDS UPON ALCOHOL. 417
sity vanes very much with its temperature, (102 ;) thus at
82° it is 0-815; at 50°, -8065; at 59°, -8021; at 68°, -7978;
and at 77°, -7933. It has a pungent and agreeable taste
and a fragrant odor. It is very combustible, and burns
with a pale blue flame without smoke, which renders it very
useful as a source of heat in chemical processes. The action
of alcohol on the system is well known as that of a power-
ful and dangerous stimulant. It is largely used in the
operations of the arts, the preparation of medicines, and the
processes of chemistry. Its solvent powers are very great :
the volatile oils and resins are dissolved by it, as well as
many acids and salts, the caustic alkalies, and a large num-
ber of other substances. .
The density of alcohol vapor is 1589#4, and its equivalent
is represented by four volumes, oxygen being one volume ;
thus —
4 volumes of carbon vapor. 4X 829. as 3316*0
12 " " hydrogen 12 X °>2 = 830-4
2 " "oxygen 2XH05-6 ss 2211-2
6357-6
Equal 4 volumes aloohol vapor, of which 1 volume weighs.... 1598*4
719. Pure alcohol dissolves several salts, as the chlorid
of calcium and the nitrates of lime and magnesia, and forms
with them crystalline compounds, in which the alcohol takes
the place of the water of crystallization, by virtue of the
homologous relation which it sustains to water. When potas-
sium is added to alcohol free from water, hydrogen is evolved
and a crystalline compound formed, in which the metal
replaces hydrogen. It is C4H5K03, and by the action
of water is decomposed into alcohol and hydrate of potash,
C4H5K09+Hfl0fl== C4H60fl-f(KH)0a. By an indirect pro-
cess, a compound is obtained in which the oxygen of alcohol
is replaced by sulphur, and which is C4H6Sa. It is a colorless
very volatile liquid, having a strong odor resembling that of
onions. Like the oxygen species, it may exchange H for a
metal ; with oxyd of mercury it forms water and a crystal-
line compound C^^jHgSj : from the violence of the action
it has received the fanciful name of mercaptan, (from mer-
curium captans!)
Action of Acids upon Alcohol.
720. It has been shown that when n in the general
formula of the alcohols becomes equal to zero, we have
27
Digitized
byGoogk
418 ORGANIC CHEMISTRY.
water 11,0,, which may be regarded as their homologue and
prototype. We have farther pointed out the fact that a
group of elements is often found to be equivalent to an atom
of hydrogen, and capable of replacing it in combination:
such is NH4 in the ammonia salts; and in the compounds of
vinic alcohol, the group C4H5 will be found to sustain simi-
lar relations. In water, which is (HH)Oa, one atom of
hydrogen may be replaced by this group, and we have then
(C4BL.H)0t, which is alcohol. In the potassium compound
just described, the second atom of hydrogen is replaced by
ft metal, and we shall presently describe a compound in
which both atoms of the hydrogen are replaced by the
organic group: it is (C.H5.C4Hs)0s=C8H100a. This
same group may also replace the hydrogen in acids; a
monobasic acid reacts with one equivalent of alcohol and
eliminates an equivalent of water, forming a compound in
which C4H5 replaces H in the acid, and renders it neutral.
Such compounds are called ethers of the various acids.
With bibasic and tribasic acids, two and three equivalents
of alcohol combine to form neutral ethers, and eliminate two
and three equivalents of water. But when a bibasic acid re-
acts with but one equivalent of alcohol, only one atom of its
hydrogen is replaced, and the second atom remains as be-
fore, capable of being exchanged for a metal. Such com-
pounds are acid ethers or vinic acids.
721. Although the ethers are thus analogous to salts in
their constitution, they are less readily decomposed than the
corresponding metallic salts ; they frequently require the aid
of heat to effect the breaking up of the combination, and are
generally more stable as their equivalent is more elevated.
The neutral ether containing sulphuric acid, for example,
does not precipitate salts of baryta, and the corresponding
vinic acid forms a soluble saTt with that base. In these,
and many other instances, the properties of the acids seem
masked in their ethers, but similar cases are met with in
the salts of inorganic bodies.
722. The action of chlorohydric acid, and other acids
containing no oxygen, upon alcohol, requires a little explana-
tion. We have seen that when HC1 acts upon a metal, the
compound eliminated is of the type Ha ; but when the hy-
dracid acts upon a hydrated oxyd, as (KH)Ofl, the same
chlorid is formed, and Ha03 is evolved ; so it is with al-
cohol, which with hydrochloric acid yields water and a body
Digitized
byGoogk
ETHERS. 419
C4HS01. As C4H5 is equivalent to H, the new ether repre-
sents chlorohydric acid, and is evidently the chlorinized
species of a hydrocarbon C4H6, which should yield with
(Cl9) the same product, as a result of direct substitution. As
water HflOs is the prototype of the alcohols, so (Hfl) is the
prototype and homologue of the carbohydrogens like C4Ha,
whose formula is CwHw+9=CnHn-|-Hjl; and chlorohydric
acid HC1 is the type of the chlorohydric ethers.
As the ethers of alcohol contain C4H6, replacing H in
the acids, and consequently differ from the latter by (CflH3)fl,
it follows that the ethers are always homologous with their
parent acids.
In describing these compounds, we shall often designate
the group C4H5 by the symbol Et, and write alcohol (EtH)Oa.
Ethers.
723. Chlorohydric Ether, C4H5C1 = EtCL— When alcohol
is saturated with chlorohydric acid gas, and heated, it is con-
verted into water and this ether, (EtH)Oa+HCl = EtCl +
Hs09. By distillation it is obtained as a pungent aromatic
liquid, slightly soluble in water, and boijing at 52° F. : at
a temperature of — 4° it crystallizes in cubes: its specific
gravity is -873.
By distilling alcohol with hydrobromic acid, or a mixture
of phosphorus and bromine, which evolves the acid, hydro-
bromic ether EtBr, is obtained as a volatile liquid heavier
than water; and by substituting iodine for bromine, hydr iodic
ether EtI is found. It is a colorless liquid, with a specific
gravity of 1*920, and a boiling point of 160° F. These
ethers are all decomposed by an alcoholic solution of hydrate
of potash into alcohol and a potassium salt, EtCl+(KH)Os
= (EtH)Os-f-KCl. By the action of potassium upon chlo-
rohydric ether, a compound is obtained in which K replaces
CI. It is C4H5K or EtK : this is decomposed by water into
hydrate of potash and a volatile oily substance C4H6, to
which the name of acetene has been given. It is the hydro-
carbon corresponding to Ha, and may be written EtII,
Another product has been formed, which is C8H10, in which
the second atom of hydrogen is replaced by C4H5 : it is EtEt,
and has a density corresponding to four volumes of vapor.
The binary grouping which prevails throughout all com-
pounds is such as to forbid the isolation of the elements
CJItf which are always grouped with a metal, chlorine, or
Digitized
byGoogk
420 ORGANIC CHEMISTRY.
even another equivalent of themselves, so that the la** of
divisibility is never violated.
724. Nitric Ether N(Et)06=N(C4Hs)06.— The action of
alcohol and nitric acid is violent and irregular, the alcohol
being oxydized at the expense of the oxygen of the acid, and
several compounds formed ; but the addition of a little urea
or nitrate of ammonia to the mixture of the acid and alcohol
prevents this, and the ether is then formed and distilled over
by the aid of heat ; water being the only other product. Nitric
acid N05H0 = NHOfl-f (EtH)Oa= NEtOe+H9Oa. It is a
colorless liquid of a sweet taste, is heavier than water, in which
it is insoluble, and boils at 185° F. Its vapor explodes by heat.
725. Nitrous Ether, or Hyponitrie Ether, N(Et)04=
C4H5N04. — When nitric acid acts upon starch, copious red
vapors are evolved, which are anhydrous hyponitrie acid NOs :
they are rapidly absorbed by dilute alcohol, with the produc-
tion of sufficient heat to cause the new ether to distil over, when
it is condensed by means of ice. Hyponitrie acid NOsHO=
NH04+(EtH)0a=N(Et)04+Hfl0a. The hyponitrie ether
is a pale yellow liquid, having a fragrant odor of apples : it boils
at 62°, and has a specific gravity of -947. It is one of the pro-
ducts of the action of nitric acid with alcohol, when urea is
not added; and a solution of the impure product in alcohol,
obtained by distilling alcohol with nitre and sulphuric acid,
constitutes the sweet spirits of nitre of the old chemists, which
is still used in medicine. If a mixture of nitric acid and alco-
hol is distilled with the addition of turnings of metallic cop-
per, pure nitrous ether may be obtained. Nitrous ether
undergoes a remarkable decomposition by the action of
sulphuretted hydrogen : the gas is rapidly absorbed, with the
separation of sulphur, and alcohol, water, and ammonia are
formed ; C4H5N04+3HaSa = Sfl+HaOa+C4H60+NH3.
Perchloric ether is obtained by an indirect process as an
oily liquid, heavier than water, having a sweet, pungent taste,
like oil of cinnamon. It explodes by slight friction, heat,
or percussion, with fearful violence. Perchloric acid being
C107HO == C1H08, the ether is C1(C4H5)08. Like the nitric
and hyponitrie ethers, it is decomposed by an alcoholic solu-
tion of hydrate of potash into alcohol and a perchlorate.
Sulphovinic Acid.
726. When sulphuric acid, mixed with its weight of
alcohoi, is heated to boiling, combination ensues with the
Digitized
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SULPHOVINIC ACID. 421
elimination of water, and sulphovinic acid is formed; sul-
phuric acid S?Hfl08+(EtH)0a=Sa(EtH)08+Hs0a. By
diluting the mixture with water and saturating it with car-
bonate of lime, the free sulphuric acid is converted into
insoluble sulphate of lime, and the soluble sulphovinate ia
obtained by evaporating at a gentle heat and cooling, ia
colorless prisms. As the carbohydrogen elements have re-
placed one equivalent of hydrogen in the sulphuric acid, the
new acid is monobasic, and the lime salt is Sa(EtCa)08
-j-HaOa : this water of crystallization is lost in a dry atmo- *
aphere. By substituting carbonate of baryta for lime, the
baryta salt Sa(EtBa)08 is obtained in fine crystals; from
this salt, by double decomposition, the sulphovinates of
other bases may be obtained. Dilute sulphuric acid preci-
pitates all the baryta from the baryta salt, and sulpho-
vinic acid, Sa(EtH)08 is obtained in solution : when concen-
trated in vacuo it forms a syrupy liquid, which is decomposed
by heat into alcohol and sulphuric acid, by taking up the
elements of water. The lime and baryta salts undergo, in
part, a similar decomposition by boiling, and after several
years, even at the ordinary temperature, are changed into
sulphates and alcohol.
With hydrate of potash a similar change takes place by
heat, and alcohol and a sulphate are formed. Sulphovinate
of potash Sa(KEt)08+rKH)0a==SaKa08+(EtH)0a; or .
neutral sulphate of potasn and alcohol. If the hydro-sul-
phuret of potash KS.HS = (KH)Sa is employed, sulphur-
alcohol (EtH)Sa is formed by a similar reaction ; and with any
salt, like the acetate of potash C4H8K04, a compound is ob-
tained, in which Et replaces K : it is C4H8(Et)04, or acetio
ether. In this way the perchloric and many other ethers
are formed by double decomposition.
727. When carefully dried sulphovinate of potash is dis-
tilled with a mixture of potassio alcohol (EtK)Oa> sulphate
of potash is formed, and a volatile liquid distils over, ia
which the second atom of H ia replaced by the elements
C4H5. Sa(EtK)08+(EtK)0a=SaKa08+(EtEt)0a. This
compound is also obtained when, within certain limits of tem-
perature, sulphovinic acid acts upon alcohol; S8(EtH)08
+(EtH)0a=SaHa08+(EtEt)0a being the products. The
result of this complete substitution may be conveniently
designated as hydrovinic ether, precisely as alcohol is hydro-
vinic acid. It has long been known in the history of tho
Digitized by VjOOQ IC
422 ORGANIC CHEMISTRY.
Bcience under the simple same of ether, which has since been
extended to a great number of allied products, and has
become a generic term. It is a colorless, limpid, volatile
liquid, and as its vapor is very combustible, should never
be brought near a flame. It has a specific gravity of -725,
and boils under the ordinary pressure of the atmosphere at
96° F. : by its rapid spontaneous evaporation it produces
great cold. It is sparingly soluble in water, and the ether
of the shops, which often contains alcohol, may be purified
by agitation with its volume of water, which dissolves the
alcohol, while the ether floats upon the surface. Although
in the liquid state it is lighter than alcohol, its vapor is
much heavier. The density of ether vapor is 2556-3 ; four
volumes then equal 10227*2, and contain two equivalents, or
eight volumes of alcohol, minus one equivalent, or four vo-
lumes of water :
2 equivalents of alcohol vapor, 2 X 6357-6 — 12715'2
1 equivalent of water H,09 — 2488-0
1 equivalent, or fonr volumes of ether vapor =\ 10227*2
1 volume of ether vapor 2556*3
Its equivalent is therefore 2C4H0Oa=C8HlaO4— ^0,=
C8H100„ or EtaOa.
728. Ether is used in the arts and in many chemical pro-
cesses as a solvent; and in medicine, internally as a stimu-
lant, and externally as a refrigerant, from the cold produced
by its evaporation. An important application was some years
since pointed out by Dr. Charles T. Jackson, of Boston, and
introduced into practice by Mr. Morton, a dentist of that
city : it depends upon the fact that the vapor of ether, when
mixed with atmospheric air and inhaled, produces a kind of
intoxication, followed by a state of stupor, in which it was
found by these gentlemen that the subject is so far insensi-
ble to external impressions, as to undergo the most difficult
surgical operations without pain. This important discovery
has been very extensively applied both in this country and
in Europe •* and the vapor of several other liquids has been
found to produce similar effects.
729. In the manufacture of ether on a large scale, the
reaction of sulphoviDic acid and alcohol is employed. When
* The French government, in token of the high importance of the dis-
covery, has bestowed upon Dr. Jackson the Cross of the Legion of Honor.
Digitized
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ETHERS.
423
the mixture of alcohol and sulphuric, acid containing sul-
phovinic acid and water, is diluted, so as to boil much
below 300° F., it is, as we have already shown, decomposed
again into sulphuric acid and alcohol ; but at about 300° F.,
the sulphovinic acid reacts upon a second equivalent of
alcohol instead of an equivalent of water, and yields sul-
phuric acid and ether. By an ingenious method, the alter-
nate formation and decomposition of sulphovinic acid may
be made to furnish an unlimited supply of the new pro-
duct. The arrangement is represented in the fig. 413.
A mixture of five parts of alcohol of 90 per cent, and
Fig. 413.
eight parts of ordinary sulphuric acid is placed in the
flask e, through the cork of which passes a thermometer t,
and two tubes, one of which d9 conveys the vapors away to
a condenser B, while the other a, which dips below the
surface of the liquid, is arranged to supply pure alcohol
from a reservoir E. The mixture is now raised to its boil-
ing point, which is about 300° F., and carefully maintained
at that temperature, so as to be in constant ebullition. Al-
cohol is slowly admitted through the cock f9 in sufficient
quantity to preserve the original level of the liquid in the
flask. In this way, as the sulphovinic acid meets with the
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424 ORGANIC OHBMISTB1
alcohol, it is decomposed into ether and sulphuric aciJ, but
this reacting upon another portion of alcohol, forms water,
which is volatilized, and a new portion of sulphovinio acid,
to be decomposed in its turn. The ether and water distil
over and are condensed together; and the same portion of
sulphuric acid will serve to convert an indefinite quantity
of alcohol into water and ether; a trace only of the sul-
phuric acid passes over. The ether is decanted from the
water, and purified by distilling from a small quantity of
hydrate of potash.
730. As it has long been obtained by the distillation of
sulphuric acid with alcohol, it was formerly called sulphu-
ric ether, a name which is still sometimes retained. The true
sulphuric ether, which corresponds to the other neutral ethers,
is obtained by the action of anhydrous sulphuric acid
upon hydric ether. It is a neutral, dense, oily fluid, and
differs from sulphovinic acid in having the second equiva-
lent of H replaced by Et, its formula being S9(Ets)08. Bv
heat it is decomposed, in the presence of water, into sul-
phovinic acid and alcohol.
731. Compounds have been obtained which correspond
to ether in which Oa is replaced by sulphur, selenium, and
tellurium. The sulphur compound is C8H10S9 or Et^ and
is obtained by the action of hydrochloric ether upon sul-
phuret of potassium 2EtCl+K8Sf = 2KCl-fEt9S8 : with
bisulphuret of potassium, a compound is obtained which is
E^S^ and corresponds to persulphuret of hydrogen H9S4.
These are volatile liquids, insoluble in water, and having
a strong odor like garlic.
732. Phosphoric acid yields several compounds contain-
ing the elements of alcohol. The tribasic acid is P05.3HO
= PH808, and the neutral phosphoric ether is P(Et8)08.
The other two compounds are P(Et9H)08 and P^EtHJOg,
and are respectively monobasic and bi basic vinic acids.
Carl: Dvinate of potash is obtained when carbonic acid gas
is passed into a solution of hydrate of potash in pure alcohol.
The acid being C9H30fl, the new salt is C2(EtK)0B. The
acid has not been isolated. The true carbonic ether is
Ca(Eta)06=C10H100B. By substituting bisulphuret of car-
bon for carbonic acid gas in the above process, carbovinates
are obtained in which the oxygen is in part replaced by
sulphur. The acid is obtained in a separate form, and is
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OLEFIANT GAS.
425
0,(EtH)(OaS4) ; from the yellow color of Home of its salts,
it has been called xanthic acid.
733. Silicic Ethers. — The action of chlorid of silicon
upon alcohol yields two silicic ethers. They are odorous,
pungent, and volatile liquids, which are rapidly decomposed
by alkalies, like the other ethers, and slowly by water alone ;
when exposed to moist air, in imperfectly closed vessels, they
evolve alcohol and are gradually decomposed, leaving hy«
drated silicic acid in beautiful transparent masses, resem-
bling rock crystal. The formula of one is represented by
C19H15Si08 which corresponds to a tribasic silicic acid
Si08.3HO = SiH806, and is Si(Et8)06. The other is
C8H10Si4014, which represents a bibasic acid 4Si08-|-H8Of
=Si4H8014; the ether being Si4Et8014.
Chlorid of boron with alcohol yields two similar ethers :
they burn with the fine green flame characteristic of boracic
acid. Boracic ether is formed when alcohol is distilled from
boracic acid, and is the cause of the green flame of an alco-
holic solution of the acid.
734. Olefiant Gas, C4H4. — When alcohol is mixed with
so much sulphuric acid that the mixture does not boil
below 320° F., the sulphovinic acid which is formed,
undergoes a decomposition different from those already de-
scribed ; it breaks up directly into sulphuric acid and ole
fiantgas, Sa(C4H5H)08 = S3(Ha)08+C4H4.
A more elegant way of preparing it is by an arrange-
ment similar to that used for pro-
ducing ether. Sulphuric acid is
diluted with nearly one-half its
weight of water, so that its boil-
ing point is between 320° and
330°, and being heated in the flask
a (fig. 414) to ebullition, the vapor
of boiling alcohol is introduced
from the flask d by the tube b,
which dips a little way in the acid.
In this process, we may suppose
that sulphovinic acid is formed
with the escape of an equivalent
of water in vapor, and is then im-
mediately decomposed into sul-
phuric acid and olefiant gas; an
equivalent of alcohol yields C4H4-f-Hfl0a.
Fig. 414.
The gas is thai
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byGoogk
428 ORGANIC CHEMISTRY.
obtained quite pure, and the process may be continued for
any length of time. This compound is a product of the
destructive distillation of many organic substances, and is
abundant in the gases for illumination prepared by the
decomposition of coal and the fat oils.
735. When mingled with its own volume of chlorine
combination ensues, and the product condenses as a heavy oily
liquid of a sweet pungent taste. It was discovered by an
association of Dutch chemists, who, from this reaction,
gave to the carbohydrogen the name of oleficmt gas. It is
C4H4C1S, and corresponds to a carbohydrogen C4He, identical
in composition with ace ten. By the action of chlorine a series
of compounds is formed by successive substitutions ; we have
C4H8C18, C4H8C14, CflHCl5 and C4C16. A similar series of com-
pounds is obtained from chlorohydric ether, which, though re-
presented by the same formulas, are unlike in their properties :
the two series afford an interesting case of metamerism.
The final product of the action of chlorine upon both
series of compounds is the chlorid of carbon C4C16. This
is a white crystalline solid, with an aromatic odor, like cam-
phor; it melts at 320°, and, at a temperature a little above
this, may be distilled unaltered. It is scarcely combustible,
and is unchanged by acids or alkalies. When its vapor is pas-
sed through a porcelain tube heated to redness, it is resolved
into chlorine gas and a new compound C4C14, which is
a volatile liquid, of the specific gravity of 1*65. If the
vapor of this compound is passed repeatedly through a tube
at a bright red heat, it is decomposed into chlorine and
C4Clr This body forms soft, silky crystals, which are vola-
tile and combustible.
The name of etlierilen has been applied to the type C4He,
metameric with aceten, and etheren to olefiant gas. The
derivatives will be monochloric, bichhric etheren, &c.
BvcMoric ether Hen, by the action of an alcoholic solution
of hydrate of potash, yields chlorid of potassium and mono-
chloric etheren C4H8C1 : the same way, trichloric etherilen
gives CaHgCl,,; and sexchloric aceten C4C16, with hydrosuk
phuret of potassium, yields C4C14.
Products of the Oxydation of Alcohol.
736. Aldehyd or Acetol, C4H40a. — The action of oxyd-
ising substances removes Hfl from alcohol and yields
Digitized
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PRODUCTS OP OXTDATION OP ALCOHOL.
427
aldehyd.* It is formed, together with nitrous ether, when
nitric acid acts upon alcohol. One equivalent of nitric
acid NHOfl+04H603=H3Of+NH04+C4H4Oa; besides
aldehyd, water and nitrous acid are the products, the latter
of which forms an ether with another portion of alcohol.
Aldehyd is best obtained by the aid of chromic acid act-
ing upon alcohol. For this purpose an apparatus may be
constructed like fig. 415, entirely of glass, which will be
Fig. 415.
found very useful for the distillation of numerous volatile
products in organic chemistry. Equal weights of pow-
dered bichromate of potash and strong alcohol are introduced
into the flask a, and 1} parts of sulphuric acid are gradu-
ally added by the safety tube s. Much heat is produced
by the mixture, and the distillation commences at once, but
is continued by a gentle lamp-heat under the sand-bath of
o. . The condensing tube t is of glass, and iced water from
the reservoir n enters and escapes by the two glass tubes
iy Vj the former of which has a funnel mouth.
The impure product is mixed with ether and satu*
* Whence its name, from alcohol dehydrogcnatu*
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428 ORGANIC CHEMISTRY.
rated with ammonia, when a compound of aldehyd and
ammonia separates in fine crystals. This, decomposed by
dilute sulphuric acid, affords pure aldehyd, as a colorless
liquid having a suffocating ethereal odor. It boils at 70° F.,
and has a specific gravity of *790 : it mixes readily with
water, and, when heated with a solution of potash, becomes
brown and deposits a resinous substance.
The abstraction of Ha seems to have been made from the
group C4H5, and CgIL appears in acetoi to play the same
part as C4H5 in alcohol. Thus, with potassium a com-
pound is formed which is (C4HVK)CL, and the crystalline
compound with ammonia is C4H .0s+NH8= (C4H8.NH4)0j,
in which NH4 replaces H. When a solution of aldehyd is
added to one of ammoniacal nitrate of silver, the metal
is reduced and lines the vessel with a brilliant film of sil-
ver. A similar process has been successfully applied to the
manufacture of mirrors.
737. Aldehyd cannot be preserved unchanged, even in
sealed tubes, but is slowly changed into two polymeric com-
pounds. One of these, elaldehyd, is a dense oily fluid,
which has none of the properties of aldehyd. The density
of its vapor is three times that of aldehyd ; and its formula
is 3C4H409 = C^H^Og. The other body, metaldehyd, forma
hard white prisms ; it is formed by the union of four equiva-
lents of aldehyd, and is C16Ht609. Aldehyd is also ob-
tained as a product of the decomposition of lactic acid or
lactate of copper by heat, and is formed in large quantity
when a lactate is distilled with binoxyd of manganese and
sulphuric acid. When the isomerism of lactic acid with
glucose is considered, it is easy to understand that while the
latter is decomposed by fermentation into carbonic acid and
alcohol, lactic acid by oxydation may yield carbonic acid
and aldehyd. We shall see, farther on, that it is possible
to reproduce lactic acid from aldehyd.
738. Chloral. — By the prolonged action of chlorine upon
alcohol a liquid is obtaiued, to which the name of chloral
has been given. It is aldehyd in which chlorine replaces
H3, and is represented by C4(IIC13)02.
Sulphur aldehyd C4H4S3 has also been obtained, and
both the trichloric and sulphuretted species yield polyme-
ric modifications similar to those of normal aldehyd. The
action of sulphuretted hydrogen upon an aqueous solution
of aldehydate of ammonia produces large transparent crys-
Digitized
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PRODUCTS OP OXYDATION OP ALCOHOL. 429
tals of an organic base, named thialdine. It is slightly
soluble in water, but dissolves readily in alcohol and ether :
the crystals are very fusible and volatile, and may be dis-
tilled with the vapor of boiling water. The formula of
thialdine a ClflH13NS4 : it corresponds to an amid of the
trimeric modification of sulphuretted aldehyd C^H^Sg.
This base has no alkaline reaction, but forms beautifully
crystalline salts. A corresponding compound, in which
selenium replaces sulphur, has been formed, but is very
unstable.
A mixture of bisulphuret of carbon with an alcoholic
solution of aldehydate of ammonia deposits sparingly
soluble crystals of a new base, called carbo-thicddine, which
is represented by C^H^N^S^ It contains the elements of
two equivalents of aldehyd, and its formation is thus re-
presented : 2C4H7NOa+C9S4=2Hfl09+C10H10NflS4.
739. Acetic Acidy C4H404. — When aldehyd is exposed
to the air it absorbs 0, and is converted into acetic acid
C4H40f+0a=C4H404. If a mixture of hydrate of potash
and lime be moistened with alcohol and exposed to heat,
hydrogen gas is evolved, and an acetate formed, C4H6Oa-t-
KH0ft=C4H8K04+H4.
740. Pure alcohol undergoes no change when exposed to
the air alone ; but if its vapor mixed with air is brought into
contact with platinum-black, it slowly unites with oxygen
to form aldehyd, which readily absorbs another portion of
oxygen and produces acetic acid. The oxydating power of
finely-divided platinum has been before alluded to ; it ab-
sorbs or condenses great quantities of gases and vapors in
its pores, where they appear to be brought together in such
a state that they readily react upon each other.
741. The formation of acetic acid may be beautifully
shown by placing a little platinum-black in a watch-glass, by
the side of a small vessel of alcohol, covering the whole
with a bell-glass, and setting it in the sunlight. In a short
time the vapor of acetic acid will condense on the sides of
the glass, and run down in drops; and if we occasionally
admit fresh air by raising the bell-jar, the whole of the
alcohol will be acidified in a few hours.
In the ordinary process for vinegar, alcoholic liquors, as
wine and cider, are exposed to the air in open vessels.
Although a mixture of pure alcohol and water does not
absorb oxygen from the air, a small portion of any ferment,
Digitized
byGoogk
480 ORGANIC CHEMISTRY.
as vinegar, already formed, or the fungus plant
called mother of vinegar, enables it to com-
bine with oxygen. In this process the essen-
tial thing is a free supply of air and a propei
1 temperature. In the manufacture of vine-
gar on the large scale, this is secured by
causing the liquor (b, fig. 416) to trickle from
threads of cotton arawn through holes, over
shavings of beech-wood previously soaked in
Fig. 416. vinegar, and contained in a large cask with
holes in its sides, (c c c c,) so as to admit a free circulation
of air. In this way a vast surface is exposed, and the ab-
sorption of oxygen is very rapid, causing an elevation of
20° or 30° in the temperature. The liquid is passed through
this apparatus four or five times in the course of twenty-four
hours, in which time the change of the alcohol into vinegar is
generally complete. The product is collected in the vessel a.
742. Acetic acid is also obtained by distilling wood in
close vessels, (712,) a process employed on a large scale for
the preparation of the acid. The products are, besides car-
bonic acid and carburetted hydrogen, a large quantity of
acetic acid mixed with oily and tarry matters, from which
it is separated mechanically. The acid thus prepared is
known as pyroliyneow acid, and is largely used in the arts
of dyeing and calico-printing ; but being contaminated by
empyreumatic oils, is not fit for the purposes of domestic
economy. By combining it with bases, salts are obtained,
which, when decomposed, afford a pure acid.
743. By distilling dried acetate of soda with strong sul-
phuric acid, a very concentrated acid is obtained, which,
when exposed to cold, deposits crystals of pure acetic acid
C4H404. The pure acid is solid below 60° F. \ when liquid,
it has a specific gravity of 1063, and boils at 248°. It is
perfectly soluble in water, alcohol, and ether ; it has a pun-
gent fragrant odor and a very acid taste, and, when applied
to the skin, is highly corrosive. The acid is monobasic ; all
its salts are soluble in water.
Acetates.
744. Acetate of potash C4H3(K)04 is easily prepared by
neutralizing acetic acid with carbonate of potash. It is a
very soluble deliquescent salt, and is employed in medicine.
Digitized
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ACETATES. 431
Acetate of soda C4H8(Na)04 forms large crystals with six
equivalents of water. It is prepared in large quantities from
pyroligneous acid; the salt is heated to destroy the oily
matters, and then affords by its decomposition a pure acid.
Acetate of ammonia C4H404+NH8 = C4Hs(NH4)04 is
used in medicine by the name of the spirit of Mindereus.
It is prepared by saturating acetic acid with ammonia, and
is exceedingly soluble and volatile. The acetate of zinc is a
beautiful white salt, and is employed as a tonic and astrin-
gent. The acetate of alumina C4Hs(al)04 is much used in
dyeing; it is obtained by decomposing a solution of alum by
one of acetate of lead ; sulphate of lead precipitates, and
acetate of alumina with acetate of potash remains in solu-
tion. The protacetate and peracctate of iron are prepared in
a similar manner, and are largely employed in calico-print-
ing and dyeing. They are represented by C4(H,Fe)04, and
C4H3fe04. (See § 649.)
745. Acetate of Lead, C4H8(Pb)04.— This salt is well
known under the name of sugar of lead. It is prepared by
dissolving oxyd of lead (litharge) in acetic acid, and crystal-
lizes with three equivalents of water, which are expelled by
gentle heat. It is a white salt, with a very sweet and astrin-
gent taste, and is often employed as a medicine ; but is poi-
sonous, and should be used internally with caution.
The acetate of lead has a great tendency to combine with
oxyd of lead, with which it forms several definite compounds.
These are generally designated as basic salts, but should be
carefully distinguished from the salts containing more than
one equivalent of base, which are formed by bibasic and
tribasic acids. In these last, the metal replaces the hydro-
gen of the acid, but in the basic acetates the neutral salt com-
bines directly with the oxyd. To distinguish them, the term
surbasic is applied, and the compound of the acetate with
an equivalent of oxyd of lead is called the surbasic acetate
of lead. Three of these compounds are known, in which
the acetate is combined with one-fourth, one, and two and a
half equivalents of oxyd. The second is the only one of
importance.
746. Surbasic Acetate of Lead, C4HsPb04+Pba0a —
This salt, commonly called the tribasic acetate, is obtained
by digesting a solution of six parts of the acetate with seven
of litharge ; the oxyd is dissolved, and the liquid affords, by
evaporation, a salt crystallizing in long needles. It is also
Digitized
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482 ORGANIC CHEMISTRY.
slowly formed when metallic lead is digested in an open
vessel with a solution of the acetate, oxygen being absorbed
from the air. The salt is very soluble in water, and its
solution has an alkaline reaction ; it is known in pharmacy
as Goulard! % extract, or solution of lead. When exposed
to the air, it absorbs carbonic acid, and the equivalent
of oxyd of lead is precipitated as a carbonate. This reaction
enables us to explain the formation of white-lead.
747. A process frequently employed is to mix litharge
and about XJ^ of sugar of lead into a thin paste with water?
the mixture is gently heated, and a current of carbonic acid
is passed through it. The acetate of lead dissolves a portion
of the oxyd to form the tribasic salt ; this is immediately
decomposed by the carbonic acid, which precipitates car-
bonate of lead, and leaves the acetate free to dissolve a new
portion of oxyd. In this way the smallest quantity of the
acetate is able to convert a large portion of the oxyd into
carbonate, and at the end of the process to remain unaltered.
748. In the ordinary process, the plates of lead are ex-
posed to the action of acetic acid, moisture, air, and the car-
bonic acid from fermenting tan, (588.) The lead immedi-
ately becomes covered with a film of oxyd by the action of
the air. This is dissolved by the vapor of the acetic acid,
and forms a solution of neutral acetate, which moistens the
plates and gradually acts upon them, forming, by the aid of
the atmospheric oxygen, the basic acetate, which is decomposed
by tbc carbonic acid, in the same manner as in the last process,
and the neutral acetate is again set free to act upon the me-
tallic lead ; the process goes on until all the lead is carbon-
ated. In this way a small quantity of acetic acid will,
under favorable circumstances, convert a hundred times its
weight of lead into carbonate in a few weeks.
749. Acetate of Copper, C4H8(Cu)04.— This salt is very
soluble, and forms beautiful green crystals of the monoclinic
system, containing one equivalent of water. The acetate of
copper forms several surbasic salts which are insoluble in
water. The fine green pigment called verdigris is a mix-
ture of two or more of these : all of these copper salts are
very poisonous. The acetate of silver C4H3( Ag)04 crystal-
lizes in white scales, and is the least soluble of the acetates.
750. Ofiloracetic Acid, C4C13(H)04.— We have already
mentioned this product of the action of chlorine upon
erystallizable acetic acid; one equivalent of the aoid and
Digitized
byGoogk
ACETATES. 4&>
three of chlorine yield three of chlorobydric acid and
one of the new compound, C4H404+3C18=C4C13(H)04
-f-3HCl. The chloracetic acid is very soluble, but may be
obtained in fine rhombohedral crystals ; its salts resemble
the ordinary acetates. When an amalgam of potassium
is added to a solution of chloracetate of potash, chlorid of
potassium, hydrate of potash, and the normal acetate of
potash are formed. In this reaction water intervenes, and
we may suppose that the alkaline metal, decomposing water,
forms 3(KH)09 and 3KH, which last, reacting with the
chloracetate, would form chlorid of potassium, leaving Hs in
place of the chlorine.
Acetic Ether y C4H8(Et)04==C9H804.— This ether is form-
ed by the direct action of acetic acid upon alcohol, but is best
obtained by diotilling a mixture of five parts of acetate of
soda, eight of sulphuric acid, and three of alcohol. It is a
very fragrant and volatile liquid, soluble in seven parts of
water. The odor of wine- vinegar is due to the presence of a
little acetic ether. It contains, like the ethers of other mo-
nobasic acids, the elements of the acid and the alcohol minus
an equivalent of water H908. The ethers like this, formed by
the acids of the type CnHw04 with their respective alcohols,
are polymeric of the corresponding aldeydes ; acetic ether
equals 2xC4H409..
Acetic ether is dissolved by a concentrated solution of am-
monia, and the solution affords by evaporation a white crys-
talline substance, very volatile and fusible, to which the name
of acetamid has been given ; it is the amid of acetic acid,
and contains the elements of acetate of ammonia less an
equivalent of water : C4H3(NH4)04 = C4H?N04 = H909 +
C4H5N0tf which is the formula for acetamid. In its form-
ation from the ether, alcohol is set free; acetic ether
C8H604 + NH8 = C4Hfl09 + C4H5N09. The ethers of
almost all acids yield amids by a similar reaction. When
heated gently with potassium, acetamid evolves a gas and
yields cyanid of potassium C9KN.
If acetamid is distilled with anhydrous phosphoric acid,
the elements H909 are abstracted from it, and a volatile
liquid is obtained, which is C4H5N0g— H909==C4H8N. It
has received the name of acetonitryl. By the action of
strong acids and alkalies both of these compounds regenerate
ammonia and acetic acid.
751. When an acetate is heated with an excess of hydrato
28
Digitized
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484 ORGANIC CHlBdSTRT.
of potash, it breaks up into carbonate of potash and a carbo-
hydrogen CgH4. Acetate of potash C4HgK04+(KH)0fl =
CsKgO6-f-0vfi4. It has already been described under the
name of marsh gas, from its occurrence in marshes, as a
product of the decomposition of vegetable matter. To indi-
cate its relations in the organic series, the name of formen
has been given to it. The chloracetates undergo a similar
decomposition, and yield trichloric formen C^Cytt, in which
Gls replaces Hr The chloracetate of ammonia is decom-
posed by boiling with an excess of ammonia, into carbonate
and this chlorinized species.
752. When an acetate is decomposed by heat, or when
the vapor of acetic acid is passed through a red-hot tube, the
acid undergoes a peculiar decomposition; two equivalents
of it unite with the elimination of one equivalent of carbonic
acid, C.H.06.2 XC4H404=C8H808— CaHs06=C8nfl09
To this liquid the name of action has been given ; by oxyd-
izing agents, like chromic acid, it yields acetic acid. We
have already mentioned aceton as a product of the distilla-
tion of sugar with lime : it is accompanied with an analogous
compound, to which the name of meiaceton has been given,
and which corresponds to a new acid homologous with acetic
acid, to which the name of metacetonic or propionic acid has
been given. It is C6H604 == C4H404+C8Hfl, and is very
much like acetic acid in its properties. When a paste of
wheat flour is fermented with fragments of white leather
and a quantity of chalk, propionate of lime is formed in
large quantity. The fermentation is probably analogous to
that which yields butyric acid. The decomposition of the
salts of propionic acid by heat furnishes directly propion or
metaceton, in the same way as butyric acid furnishes the
homologue butyron. By the action of nitric acid upon
butyron, a coupled acid is obtained, which is nitropropionio
acid C6(H5N04)04=C.H5N08.
Methol, CJE^O,.
753. Wood-spirit, Pyroxylin Spirit, Methylic Alcohol.*—
This substance has already been mentioned as a product of
* Pyroxylic spirit, from pur, fire, and xulon, wood. Methylio alcohol,
from methu, wine, and hule, wood; signifying the wine or alcohol of wood.
In names like kakodyl, and the terms ethyle, amyle, in the language
of the compound radical theory, the same syllable is derived from huU,
in its more extended sense of matter or prinoiple.
bigitized by G00gle
METHOL. 435
the destructive distillation of wood. The acetic acid of the
crude product being saturated with lime, impure methol is
obtained by distillation, and is afterward purified by re-
peated rectifications. It is a colorless liquid, of a peculiar
and somewhat unpleasant odor, and a hot, pungent taste.
It has a specific gravity of -798, and boils at 152° ; it ia
very combustible, and burns with a pale blue flame. Like
alcohol, it mixes in all proportions with water. It is occa-
sionally used in the arts for dissolving resins and making
varnishes, and the pure wood-spirit has lately acquired
some celebrity in the treatment of phthisis, under the name
of wood-naphtha. Like vinic alcohol, methol forms crystal-
line compounds with several salts and with baryta. It
furnishes derivatives in which H is replaced by K, and
Oa by Sa. The nitric ether of methol is obtained by the
direct action of the acid upon the alcohol, and resembles
the vinic compound. The chlorohydric ether CflHsCl is a
colorless gas.
The hydrobromic and hydriodic methylic ethers, ob-
tained by processes similar to those described for the corre-
sponding vinol compounds, are liquids at the ordinary tem-
perature. In the bodies of this series, which is homologous
with that of vinic alcohol, CjjHg plays the same part that
we have assigned to C4H5. This group may be designated
by Me, and wood-spirit will be (MeH)03, while the chlorid
is MeCl and the nitrate N(Me)08. These ethers are decom-
posed by a solution of hydrate of potash, with the formation
of potash salts and methol.
754. The sulphomethyiic acid is prepared in the same
manner as the sulphovinic; and like it, is an acid ether.
It is S3(MeH)0s. It is more stable than the sulphovinic
acid, and may be obtained in crystals. The neutral sulphuric
ether is prepared by distilling wood-spirit and sulphuric
acid, and is Sa(Me3)Os ; by boiling water it is converted
into sulphomethyiic acid and methol; S3(Me3)08-f-H30a=
S3(MeH)08-f-(MeH) 03. With ammonia it undergoes a
partial decomposition, and yields sulphamethane and wood-
spirit; S9rMefl)08+NH8=CaH403+Sa(C3H5N)08. The
nature of the action will be understood by referring to what
has been said of ace tarn id ; it is the amid of sulphomethyiic
acid, and by hydrate of potash is decomposed into a sulphate,
methol, and ammonia.
When sulphomethyiic acid is decomposed by heat, methyiia
Digitized
byGoogk
436 ORGANIC CHEMISTRY.
ether is obtained as a colorless gas. The principles involved
in its formation are the same as those which have already
been explained in speaking of the ether of spirits of wine.
Its formula is C4H8Oa = Mefi^ and it is consequently
metameric with vinic alcohol.
755. The chlorohydric ether of alcohol has been shown
to correspond to a carbohydrogen aceten, C4H6 = (CaHf)3Ha;
in the same manner the methol compounds are derivatives
of a homologous hydrocarbon (CaHa) Ha = CJB.# which is
formen or marsh gas, already described as a result of the
decomposition of the acetates. By the action of chlorine
the atoms of hydrogen may be successively replaced, and
the final result is C8C14, a chiorid of carbon. The trichlorie
species CaHCl8 is of some interest, and is commonly known
by the name of chloroform. Its formation by the decompo-
sition of chloracetate of ammonia has already been mentioned,
but it occurs as a product of the action of chlorine or hypo-
chlorites upon many organic substances. When alcohol or
wood-spirit is distilled with a solution of two or three parts
of chiorid of lime in twenty of water, chloroform is the prin-
cipal product ; it is a dense oily liquid, having a specific
gravity of 1480, boils at 141° F., and is nearly insoluble
in water. It has a pleasant aromatic odor and a very sweet
pungent taste. An alcoholic solution of it, prepared by dis-
tilling chiorid of lime with an excess of alcohol, has long
been known in medicine by the incorrect name of chloric
ether. Its vapor, when mixed with atmospheric air and in-
haled like ether, produces insensibility; as it is more agree-
able to the senses and more potent in its operation, chloro-
form has, to a considerable extent, replaced ether as an
anaesthetic agent in surgical practice.
The action of potash upon an alcoholic solution of iodine
produces a yellow crystalline substance, which is iodoform,
the iodine compound corresponding to chloroform, and is
09HI8. These compounds with an alcoholic solution of
hydrate of potash are decomposed into formate, with chiorid
or iodid of potassium, and water; CaHCl8+4(HK)Oa == Cf
(HK)04+3KCl+2HaOa. The hydrocarbon CaHa, corre-
sponding to olefiant gas, is not known in this series, but the
final action of chlorine upon chloroform produces CaCl4, which
is a dense liquid; at a red heat it loses Cla and is converted
into a crystalline chiorid CaCla which is the perchloric spe-
cies of the unknown GJI^ or perhaps polymeric of it.
Digitized
byGoogk
METHOL, 4P7
Oxydation of Methol.
756. When the vappr of methol mixed with air, is exposed
to the action of platinum black, oxygen is absorbed, and
water is formed with a new acid, which is homologous with
acetic acid, CaH40a -f 04 = H30fl + CaHa04. The inter-
mediate product QJIfix corresponding to aldehyd, has"
never been obtained. The action of heated hydrate of potash
upon wood-spirit evolves hydrogen, and forms a salt of the
new acid, to which the name of foivnic acid is given. It is
eecreted by a species of ant, (Formica rufa,) from whence
it derives its name, and by the stinging nettle, (Urtica
urens ;) it is also the result of the action of oxydizing agents,
upon many organic substances, as sugar and alcohol, and
may be advantageously prepared by the following process : —
800 grains of bichromate of potash and 300 of sugar are
dissolved in seven ounces of water. The mixture is placed
in a retort, and one measured ounce of sulphuric acid very
gradually added ; it is then distilled (tig. 415) with a gentle
heat, until three ounces of liquid are obtained. This is
dilute formic acid, and may be used to form salts, which,
when decomposed, afford a strong acid.
The pure acid is obtained by passing sulphuretted hydrogen
gas over dry formate of lead ; sulphuret of lead and formic
acid are produced. The action is aided by a gentle heat,
and the acid distils over. It is a colorless liquid, of specific
gravity 1*168, which boils at 212°, and at 32° crystallizes,
like acetic acid, in shining plates. It fumes in the air, and
has a very pungent odor, resembling that of ants; it is
powerfully acid and corrosive, instantly blistering the skin.
When this acid or its salts are heated with strong sulphuric
acid, it is decomposed with the evolution of pure carbonic
oxyd gas : C3Ha04 = Ca0a-f-H303. The formates resemble
the acetates. The formate of silver Ca(HAg)04 is decom-
posed when its solution is boiled ; the silver is precipitated,
while carbonic acid and carbonic oxyd gases escape,
2Ca(HAg)04 = Ag3+H30a+Ca04+C30a-
757. Formic acid yields with alcohol an ether which is
Ca(HEt)04 = C6H604. The acetic ether of methol has
the same composition C4(H8Me)04 = C6H604. These two
ethers are similar in their general physical characters, but
by the action of hydrate of potash, one yields a formate and
alcohol, and the other an acetate and methol. The formic
Digitized
byGoogk
438 ORGANIC CHEMISTRY.
ether of methol is C,(HMe)04 = C4H404 : it is metamerie
with acetic acid. All of these ethers by the action of chlorine
exchange their hydrogen in whole or in part for that ele-
ment. The final result of the substitution in formo-methylic
ether is C4C1404. We have already shown that such ethers
are polymeric of the corresponding aldehyds. The chlorin-
ized ether by heat is resolved into two equivalents of phos-
gene gas C4C1404 = 2CaClaOa ; phosgene gas is, in fact, the
chlorinized derivative of methylic aldehyd, which will be
CaHaOa.
Amylol, C10Hm09.
758. Amylic Alcohol. — We have already alluded to this
compound as a product of fermentation under certain circum-
stances. In the rectification of the crude spirit obtained by
the fermentation of potatoes, it separates as an oil, which
comes over with the last portions of the spirit, and is inso-
luble in water : the distillers give to it the name of /ousel
oily or potato oil : it is sometimes observed in the spirit
from other sources, and seems to be a product of the trans-
formation of starch or sugar, under conditions not well
understood. When pure, it is a colorless liquid, which is
insoluble in water, has a specific gravity of -818°, and boils
at 269° F. It has a burning taste, and a pungent odor
which excites coughing and often nausea.
In its chemical relations it is precisely similar to alcohol,
and methol, with which it is homologous ; its formula is
C10H13Ofl=(CioHii-H)()a; it forms ethers in which C^H^,
corresponding to CaH8, to C4HS, and to H, replaces hydrogen;
we shall represent this group by the symbol Ayl.
The chlorohydric amy lie ether is formed by the action
of the acid upon amylol, and is C10HljLCl = AylCl. The
bromine and iodine compounds are similar, as also the
nitrous and nitric ethers, the latter being N(C10H11)08, or
nitric acid in which Ayl replaces hydrogen ; as in all similar
reactions, H30a is eliminated in its formation, and it rege-
nerates a nitrate and amylol by the action of an alcoholic
solution of hydrate of potash. * With sulphuric acid, sulpha*
mylic acid, corresponding to the sulphovinic, is formed, which
is monobasic j by its decomposition, amylic ether C^H^O,
is obtained, which corresponds to the hydric ether of alcoho1,
and is Ayl303, or water in which the group C^H^ has re-
placed both equivalents of hydrogen. By tha action of an
Digitized
byGoogk
AMYLOL. 439
excess of sulphuric acid, the carbohydrogen CltH10, corre-
sponding to defiant gas, is obtained : the alcohol breaks up
into C10H10 and HaOa.
759. Oxydation of Amylol. — By the action of platinum
black, amylol combines with oxygen and is converted into
an acid homologous with the acetic and formic acids : when
heated with hydrate of potash, hydrogen is evolved, and a
salt of the same acid is formed, C10HlflOa+(KH)Oa =
G10(H9K)04+Ha. By distilling the potash salt with sul-
phuric acid, the new acid C10H1004 is obtained. It is iden-
tical with that previously known to exist in the root of the
Valeriana officinalis, and hence called valeric or valerianic
acid. It is also found in several other plants, and decay-
ing cheese sometimes owes its peculiar flavor to a proportion
of valeric acid. It is a colorless oily liquid, which is solu-
ble in a large quantity of water, is strongly acid and caustic,
and has the characteristic odor of valerian root; it boils
at 347°, and has a specific gravity of -937. Its salts are all
soluble in water and monobasic ; they have a slight odor
like the acid. The valerate of zinc crystallizes in white
scales, and is employed in medicine as a substitute for vale-
rian, the medicinal properties of which it possesses in a high
degree. The action of chlorine upon the acid affords a pro-
duct similar to chloracetic acid.
The valeric acid yields with amylic alcohol an ether which
has, when pure, an agreeable flavor, like apples. The acetic
ether of amylol has a no less striking resemblance in its
odor to jargonelle pears ; the flavors are not however deve-
loped until the ethers have been diluted with alcohol. These
ethers are obtained by distilling mixtures of amylol and
acetic or valeric acid with sulphuric acid, and are used to
give the peculiar flavors of the fruits in perfumery and con-
fectionery.
760. In ascending the series of alcohols, in proportion as
the amount of carbon and hydrogen is greater, the bodies
become more insoluble in water, and assimilated to the
oils and fats and to the different species of wax, to which they
have intimate relations. These bodies are generally ethers
of acids, which are for the most part homologous with acetic
and valeric acids; or glycerids, a class of compounds analo-
gous to ethers in their composition. From them several
new alcohols are obtained, and a still greater number of
Digitized
byGoogk
440 ORGANIC CHEMISTRY.
acids pertaining to the alcohol series. We shall first notice
those which belong to the class of compound ethers.
Spermaceti. — This substance occurs mixed with oil, fill-
ing large cavities in the head of the sperm whale, (Physeter
macrocephalus.) The oil is removed by pressure, and finally
by washing in a dilute solution of potash, and the sperma-
ceti is obtained as a white solid, which fuses at 120°, and
crystallizes on cooling in beautiful broad pearly plates. It
is soluble in alcohol and ether, but insoluble in water, and
is used in pharmacy and in the fabrication of candles.
Spermaceti has the composition of a compound ether, and,
when gently heated with hydrate of potash, is decomposed
into the potash salt of a new acid C10(H15K)O4, and the
alcohol of that acid CiaH18Oa. The acid has been called
ethalic acid, and the alcohol ethal or ethol ; spermaceti cor-
responds to the acetic acid of vinic alcohol, and contains the '
elements of the acid, and the alcohol minus H303. Both
of these are white crystalline volatile substances, analogous
in physical properties to spermaoeti. Ethalic acid melts at
131°; it yields with other alcohols, ethers which are fusi-
ble and crystalline. Ethal forms with sulphuric acid the
mlphethalic acid, corresponding to the sulphovinic, and when
heated with hydrate of potash to 400°, evolves hydrogen,
and is converted into ethalate of potash.
761. Wax. — This substance has been supposed to be a
vegetable production, and to be collected by bees from the
plants upon which they feed ; but experiments have shown
that they yield wax even when fed upon pure sugar or
honey, and that it is a secretion of the insects themselves*
A species of wax brought from China is very analogous to
spermaceti in its composition, and when decomposed by
hydrate of potash, yields the salt of a new acid, called the
cerotic avid, and the corresponding alcohol cerotol. The
acid has the formula C54H5404 and the alcohol is C^H^O^
These compounds are less soluble and fusible* than the
ethalic series ; the wax fuses at 182° F., and the alcohol
at 174°. The alcohol yields with sulphuric acid a coupled
monobasic acid, and with chlorine a product which corre-
sponds to a chlorinized aidehyd. Heated with hydrate of
potash, cerotol evolves hydrogen and is converted into cero-
tate of potash. It cannot be distilled without partial change,
being converted into water and carbohydrogens polymeric
with defiant gas.
Digitized
byGoogk
GLTCERIDS. 441
Common beeswax is separated by boiling alcohol into a
soluble portion, and a residue comparatively insoluble. The
soluble part consists principally of cerotic acid in a free
state. The insoluble part is decomposed by potash into
ethalic acid, and a new alcohol, mellisol, which is repre-
sented by C^IIogO, : it is crystallizable, and melts at 185°.
When fused with potash it yields melliric acid C^H^O^
GLYCERIDS.
762. Under this title may be included a number of neutral
fats and oils, which, by the action of bases, are converted
into salts of fatty acids, with the separation of a substance
to which the name of glycerin has been given, in allusion
to its sweet taste, (from gluku*, sweet.) Glycerin is pre-
pared by heating a mixture of olive-oil, oxyd of lead, and
water. The oil is decomposed, and the acids form insoluble
salts with the lead, while the glycerin is dissolved in the
water; the solution is treated with sulphuretted hydrogen
to precipitate a little dissolved oxyd of lead, and evaporated
in a water-bath. It is formed in large quantities as a pro-
duct of the saponification of fats by boiling with hydrate
of lime and water. The liquid which separates from the
insoluble lime salts is a watery solution of glycerin con-
taining a little lime; this may be separated by carbonic
acid, and the glycerin is then obtained by evaporation.
The formula of glycerin is C6H806. It is a colorless,
syrupy liquid, with a specific gravity of 1*280, of a very
sweet taste, and is readily soluble in water and alcohol;
it is not volatile, but when strongly heated is decomposed,
evolving acetic acid and other products, the most important
of which is acrolein.
763. Acrolein is also produced when the glycerids are
decomposed by heat, and is best obtained by distilling gly-
cerin with anhydrous phosphoric acid. The glycerin loses
the elements of two equivalents of water : C8Hg06— 2Ha03=*
CeH40fl, which is the formula of acrolein. It is a colorless,
very volatile liquid, with a peculiar acrid, penetrating odor,
which is perceived when the fat oils are strongly heated ;
it is lighter than water, and sparingly soluble in that liquid.
With potash it reacts like aldehyd, and it reduces oxyd of
Digitized
byGoogk
442 ORGANIC CHEMISTRY.
silver with the formation of a new acid, the acrylic, which
is CeH404. It resembles the acetic acid in its properties,
and under the influence of alkalies is converted with oxy-
dation into a mixture of formic and acetic acids; CflH404-(-
2(HK)0,+0,=C4(H,K)04+C,(HK)04+HaOs.
764. The constitution of the glycerids is such, that in de-
composition they combine with the elements of 3H8Os, and
produce two equivalents of a fatty acid and one of glycerin.
All of them undergo this change when heated with a solution
of hydrate of potash or soda, or with oxyds, like oxyd of lead
and lime. The salts thus formed are soaps; and different
kinds of soaps are produced, according to the nature of the
fatty acid and the alkali. Those of potash are very soluble
and remain mixed with the water, glycerin, and excess of
alkali employed in their preparation ; they form soft soaps,
while those of soda are less soluble and more easily sepa-
rated from the liquid, and constitute hard soaps. Those of
lime, lead, and other bases are insoluble in water, and the
lead-plaster or diachylon of surgeons is a lead soap. When
a solution of a soap with an alkaline base is mixed with a
salt of any other base, double decomposition ensues, and an
insoluble earthy or metallic salt is precipitated ; it is the
presence of salts of lime or magnesia in natural waters;
which gives them the power of decomposing soaps, and con-
stitutes what is called hardness in water. Strong acids in
the same way decompose soaps, and separate the fatty acid
in an oily form. Strong sulphuric acid decomposes the
glycerids like an alkali, and liberates the fatty acids, form-
ing with the glycerin an acid analogous to the sulphovinic,
to which the name of sulphoglyceric acid is given.
Butter consists of several glycerids which are difficult of
separation. When saponified, and the soap decomposed by
distillation with sulphuric acid, it yields four volatile acids,
homologous with the acetic. They are called the butyric,
caproic, caprylic, and capric acids. Of these the first is
best known : the others are separated from it, and from one
another, by the different solubility of their baryta salts.
Butyric acid is more easily obtained by the fermentation
of sugar under certain conditions, which have already been
explained, (700.)
The butyrate of lime is decomposed by a solution of car-
bonate of soda, and the soda salt being concentrated by eva-
Digitized
byGoogk
GLYCERID8. 443
poration is mixed with an excess of sulphuric acid, when the
butyric acid rises to the surface as an oily layer, which is
separated and purified by distillation. It is a colorless liquid,
which boils at 327° F., and is lighter than water. It mixes
with pure water and alcohol in all proportions. The odor of
butyric acid is strong and disagreeable, resembling that of vi-
negar and rancid butter ; it is powerfully acid and caustic.
The salts of butyric acid are all soluble in water; the buty-
rate of lime C8(H7Ca)04 is less soluble in hot water than in
cold, and separates almost entirely by boiling, in transpa-
rent prisms, which redissolve as the liquid cools.
765. By mixing together alcohol, butyric acid, and strong
sulphuric acid, the heat evolved is sufficient to cause the
formation of butyric ether, which is precipitated on adding
water to the mixture, being insoluble in it. It is a colorless
liquid, soluble in alcohol, to which it gives the flavor of pine
apples; the solution is used by confectioners to flavor syrups,
and by distillers in the fabrication of spirits.
766. When a mixture of glycerin and butyric acid is
heated with sulphuric acid, an oily liquid is obtained, which
is supposed to be the butyric glycerid, to which butter owes
its peculiar flavor. It is the only glycerid which has been
formed artificially ; by alkalies it yields glycerin and a buty-
rate like the natural glycerids ; its composition, agreeably to
the rule which we have stated, will be 2C8H804-f-C6H8Oe
-8H,Of = 0«HttOr
The distillation of butyrate of lime affords butyron corre-
sponding to aceton, and a volatile liquid, butyral C8H808 ;
it absorbs oxygen from the air, yielding butyric acid, and is
the aldehyd of the butyric series.
The oil of the porpoise (Ddphinv* phocd) contains a gly-
cerid, to which the name of phocenin has been given : it is
the glycerid of valeric acid, which has been described by the
name of phocenic acid. The action of nitric acid upon castor-
oil yields a volatile oily acid with a fragrant odor, to which
the name of enanthylic acid has been given; it is C14H1404;
and the distilled water of the rose-geranium (Pelargonium
roseuni) contains another, pelargonic acid, 018H1804.
The peculiar flavor or bouquet of wine is due to a small
portion of a peculiar ether, which is obtained when great
quantities of wine are distilled, and possesses, in a high
degree, the vinous flavor. By hydrate of potash it is de-
composed into alcohol and a volatile acid, which has the
Digitized
byGoogk
444 ORGANIC CHEMISTRY.
composition of pelargonic acid, and is probably identical
with it.
The foregoing acids are all odorous, more or less soluble
in water, and may be distilled over with its vapor ; their
boiling points, however, become gradually higher, and their
lime and baryta salt less and less soluble. Beyond caprio
acid CanHfl004, they are solid at the ordinary temperature,
no longer volatile with the vapor of water, and yield with
lime and baryta insoluble salts, and with the alkalies proper
soaps. Among these the ethalic, cerotic, and melissic have
already been mentioned. We shall notice a few of the more
important ones remaining.
767. The palm-oil which is expressed from the nuts of
the Elais guinensis is composed of a fluid fat, olein, and a
solid crystalline substance to which the name of palmatin
has been given ; it is the glycerid of ethalic acid, which is
sometimes named palmitic acid. The fat of animals is
composed in like manner of a liquid fat and a solid crystal*
line material. By careful pressure in the cold, this separa-
tion may be in part effected, and if the fats have been kept
for a long time in fusion, the solid portions crystallize out
more or less perfectly on cooling. It is by taking advantage
of this property that lard-oil is made. The solid portion
may be purified by crystallization from ether. That ob-
tained from beef and mutton consists principally of two
substances, to which the names of margarin and stearin
have been given. The former is readily soluble in ether,
and fuses at 116° F. ; stearin, on the contrary, is very
little soluble in cold ether, and melts at 130°. By saponi-
fication they yield margaric and stearic acids, one fusing at
140°, and the other at 168°. Although thus distinguished,
these bodies have the same composition : they are both mo-
nobasic and have the formula C^H^O^ The margaric haa
been distinguished by the name cf para-stearic acid. The
action of heat and of acids under certain conditions converts
stearic acid into this isomeric modification. While marga-
rin and stearin are mingled in beef and mutton fats, the
oils, like olive-oil, consist of margarin and olein. Human
fat yields by saponification a large amount of palmitic acid,
with some margaric, and a new acid, which is probably
768. The olein of lard, of olive-oil, and of almond-oil,
yields by saponification an acid which is called oleic acid,
Digitized
byGoogk
OLYOERIDS. 445
and, like olein itself, is a colorless liquid, insoluble in water.
It has a slightly acrid taste, and its alcoholic solution has an
acid reaction. Its composition is represented by C88HM04.
Oleic acid does not therefore belong to the series of homo-
logous acids already described, but is one of a new series,
of which acrylic acid C6H404 is also a member; in this
series the number of equivalents of oxygen is four, and that
of the equivalents of carbon is always two more than the
number of the hydrogen.
769. When the- vapor of nitrous acid is passed through
oleic acid, this is rapidly transformed into a crystalline sub-
stance, which is daidic acid, and is an isomeric modifica-
tion of the oleic acid. The action of the nitrous vapor upon
olein produces a corresponding modification of the glycerid.
Elaidic acid, like oleic, is monobasic, and forms beautiful
crystals, which melt at 112°. When these acids are fused
with hydrate of potash they undergo a remarkable trans-
formation ; their homologue, acrylic acid, gives acetic and
formic acids, while the oleic and elaidic yield acetic and
ethalic acids with the evolution of hydrogen : C^H^O^
2(101)0,= Oil(HaiK)04+04(HiK)04+Hr
The acid from the saponification of a variety of whale-oil
has been found to have the formula CagHggO^ and another
from the vegetable oil of the Moringia aptera C80HM04,
while the olein from human fat has yielded anthropic acid
CMH8304. All of these are monobasic and are homologues
of acrylic acid and oleic acid. Their decomposition by
hydrate of potash will probably yield corresponding acids
of the acetic series. Thus, C89H8604, to which the name of
dasglic acid ha? been given, should yield stearic and acetic
acids.
770* Castor-oil from the seeds of Ricimts communis is
distinguished from other fixed oils by its ready solubility
in alcohol. The solid fatty acids which it yields, appear to
be margario.and palmitic; the olein affords by its sapo-
nification an oily acid, which, while containing carbon and
hydrogen in the same proportion as in the last series, has
six equivalents of oxygen. Different experimenters have
apparently obtained from different specimens of oil two
homologous acids, to which they have ascribed the formula)
C88H*0« and CgeH^Og. To both of these the name of
ricinolcic acid has been given. With nitrous vapor, castor-
oil yields a crystalline glycerid like olive -oil.
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446 ORGANIC CHEMISTRY.
771. We have then three homologous series among the
fatty acids ; the first and most complete is that homologous
with acetic and etbalic acids ; the second is that of oleic
acid ; the third that of ricinoleio acid.
The first has the general formula C.H.O^ the second
C.H^O,, and the third CnHn_8Oe.
The series of the first, as far as known, is here given :—
1. Ferrate... GAO,
2. Acetic... C4HA
3. PropUmU? ,.......*„ C^^Og
4. Butyric 0,11,0,
5. Valerie,. C„H„04
S. Cuiroic CJtn„04
7. Etmnthjlic (Q&J)*
8. & ; rylis<_.,.„ CltHli04
9. PtlirgrjBio..... G-Hlt04
10. Capri* C^II^O,
11. M.irgnritfe,. <W>4
12. Lnurie C*H„04
13. Cc ink c»IIi;04
14. Mvriatk C^II^O,
15. B( :,-,■ C.JIJX
16. Ethalie C^H^
17. Stearic C^H^
18. Bassic CaiH1,04
If. Balenio CwHai04
20.
21.
22. Behonic C^H^
23.
24.
25.
26.
27. Cerotic CLH^O*
28.
29.
30. Melisaic C#0H^04
772. We have already described the alcohols of the 1st,
2d, 5th, 16th, 27th, and 30th acids, and we have to add
that of the 16th. In this group there is a regular transition
*rom formic acid, through the propionic, butyric, and other
paringly soluble oily acids, to the insoluble ethalic and
stearic. In the first ten, which are liquid at ordinary tem-
peratures, and distil without any change, there is a progres-
sive increase of about 36° F. in the boiling point of each
acid. Thus, the formic boils at 212°, the acetic at 212°+
36° =248°, and the propionic at 248°+36° =284°. The
fusing point of the solid acids rises in a similar manner, but
with less apparent regularity.
The fact that the acids are less fusible than their glycerids
has led to their use in the manufacture of candles, which
are sold under the name of stearine, adamantine, or Belmoni
qmm. The tallow is commonly saponified by heating it in
vats by steam, with a mixture of lime and water ; an insolu-
ble lime salt is formed, and the glycerin remains dissolved in
the water. This salt is decomposed by diluted sulphuric
or chlorohydric acid, with the aid of heat, and the mixed
acids, which rise to the surface, are, when cold, submitted
to pressure, by which the oleic acid is removed, and the
stearic and margaric acids are obtained nearly pure. The
crystalline tendency of the fused acid is corrected by adding
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GLYOEEIDS. 447
a little pulverized gypsum to the mass for the fabrication of
candles.
The decomposition of the glycerids by sulphuric acid,
already described, is sometimes employed for this purpose.
The higher acids of the series may be distilled without change
in vacuo or in a current of steam, but undergo a partial de-
composition when distilled in the ordinary manner. These
acids may be distinguished from stearin, from wax, and
spermaceti, for which they are often substituted, and with
which the latter are frequently adulterated, by their ready
solubility in alcohol, and in a heated solution of carbonate
of soda.
778. The action of nitric upon oleic acid yields the volatile
acids of the above series, from the acetic to the capric inclu-
sive; the other fatty acids yield similar results, and the
stearic acid is the first product of the action of nitric upon
oleic acid. The residue of the action of nitric acid contains
four soluble crystallizable bibasic acids — the succinic, CgH0O8,
adipzc, ClaH1008, pimelic, C14Hia08, and suberic, C18HU08 ;
they correspond to homologues of oleic acid, which have fixed
04, and are represented by CnH^O,. The succinic acid was
originally obtained by distilling amber, a fossil resin which
occurs in recent geological formations. Succinic acid is
soluble in water and alcohol ; when heated it fuses, and is
decomposed into water and a neutral crystalline substance
called succinid C8H40fl, which, when boiled with water, is
gradually reconverted into succinic acid. The other acids
are of but little importance ) the suberic is a product of the
action of nitric acid upon cork. When olein or oleic acid
is distilled, sebacic acid is obtained ; it is crystallizable, vola-
tile, and soluble in water, and has the formula C^H^Og,
being homologous with those just mentioned. When fused
with hydrate of potash, these acids are decomposed, and
yield members of the acetic series. Thus, the pimelic forms
valerate of potash, and, instead of the acetic acid and hydro-
gen which the homologues of oleic acid would yield, carbonic
acid and water are obtained.
774. Castor-oil and ricinoleic acid, like olein, yield sebacio
acid by distillation. When ricinoleic acid is distilled with
an excess of a strong solution of hydrate of potash, sebacate
of potash is formed, and hydrogen is evolved, with a peculiar
oily liquid, having the formula C16H18Oa. The reaction may
be thus represented: C86HMOfl + 2(KH)Oa =0^(11^)0,
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448 ORGANIC CHEMISTRY.
-l-C^HjgOj+H,. The new volatile product is the alcohol
corresponding to caprylic acid, and may be named capryhl.
ft is insoluble in water, has an agreeable aromatic odor, a
specific gravity of -823, and boils at 356° F. With sul*
phurio acid it forms a vinic acid, and with acetic and chloro-
hydric acids, ethers similar to those of ordinary alcohol ; by
oxydation it yields caprylic acid CieH1804.
775. The different animal fats generally yield, by saponi-
fication, small portions of one or more of the volatile acids
already described, and many of them are met with in the
distilled water of various plants. Many glycerids appear to
undergo a slow, spontaneous decomposition when moist;
glycerin is liberated and may be removed by water, while
the acids are found in a free state. The alcoholic ethers of
all these fatty acids may be obtained by passing chlorohydric
acid gas through their alcoholic solutions, or by heating the
same solutions with sulphuric acid : they are, like the gly-
cerids, neutral, fusible, fatty bodies, and have the same
constitution as their homologue, acetic ether. When a gly-
cerid is dissolved in alcohol and treated with chlorohydric
acid, the ether is formed in the same way, and may be pre-
cipitated by adding water, which will be found to retain
glycerin in solution. The action of ammonia alike upon
the ethers and glycerids enables us to obtain the amids of
the fatty acids with the separation of alcohol or glycerin.
They have the same constitution as aoetamid, and are all
decomposed by hydrate of potash, with the formation of a
salt of the acid and ammonia. Those of the higher acids
are solid insoluble fatty bodies.
Alkaloids op the Alcohol Series.
776. The relations between hydrogen represented as H9,
water, and ammonia have already been considered, and we
have shown that the alcohols may be viewed as compounds in
which the groups CaH3, C4H5, C^H^, &c. replace H in water.
These same groups may replace the successive equivalents
of hydrogen in ammonia and oxyd of ammonium, giving rise
to an interesting class of bodies which are perfectly analo-
gous to ammonia in their chemical relations, and are called
organic alkalies or alkaloids. Besides these obtained from
the alcohols, there are many other alkaloids, products of dif-
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ALKALOIDS OF THE ALCOHOL SERIES. 449
ferent transformations of organic bodies; others exist ready
formed in plants. We shall in this place consider only
the first class.
777. When chlorohydric, or better bromohydric ether, is
digested with a concentrated solution of ammonia, it slowly
dissolves. This operation is accelerated by heat, and is best
effected by exposing the ether and ammonia hermetically
sealed in glass tubes, to the heat of boiling water. The solu-
tion is soon effected, and the mixture, on cooling, is found
to contain a salt of the new ether-ammonia : hydrobromic
ether, EtBr-j-NH3=NH8Et.Br, bromid of ethammonium,
or NHaEt.HBr. When decomposed by lime or potash in
the same way as sal-ammoniac, the new alkaloid NHflEt,
which is named ethamine, is obtained as a very volatile
liquid, with a specific gravity of -696. It has a powerful
odor resembling that of ammonia, and its solution is very
caustic, acting like a strong alkali with acids and metallic
salts. It is soluble in all proportions in water and alcohol.
778. If a hydracid ether of methol be substituted for the
vinic ether, a corresponding methylic ammonia, or metha-
minef may be obtained, which is NHa(CaHa) or NHaMe.
It is a colorless gas, which at a low temperature may
be condensed into a liquid, and is very soluble in water,
which dissolves in the cold 1154 times its own volume of
the gas. The solution is powerfully acrid and caustic, and
in its odor and chemical properties closely resembles am-
monia; the gas is combustible. The salts of these new
bases are like those of ammonia, but are more soluble.
When placed in contact with a new equivalent of the
ether, these alkalies react with it precisely like ammonia
itself, and salts of new alkaloids are obtained, in which two
and three atoms of hydrogen are successively replaced by
the carbohydrogen elements. In this way NHEta and
>NBt^=NCttH15 are obtained; and by using successive dif-
ferent ethers, mixed alkaloids may be formed, such as
NHEtMe and NMeaEt. The amy lie and cetylic ethers yield
perfectly analogous compounds. Amylamine is NHaAyl =
WHa(C10H11). It is a very mobile liquid, having a specific
gravity of -750, and boiling at 203° ; it has at the same time
the odor of ammonia and of the amy lie compounds, and is very
caustic and alkaline. We may even have N(Me.Et. Ayl), in
which the elements of three different alcohols are united.
These higher alkaloids are liquids, which have still the cha-
29
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450 ORGANIQ CHEMISTRY.
meters of ammonia, but are less volatile and caustic than those
of lower equivalents.
779. When triethamine NEt8 is brought in contact with
another equivalent of hydriodic ether, it no longer decom-
poses it, but unites directly with it to form a salt. This
ether EtI, as we have already shown, corresponds to HI,
and the ammonia unites with it as it would with the acid:
in the latter case a simple ammonia would form iodid of
ammonium NH4I, and the trivinio ammonia N(Et3H)I ; but
with the ether it forms NEt,.EtI=NEt4I, or the iodid of
vinic ammonium NEt4. The new iodid forms fine crystals,
which have all the reactions of an ordinary iodid with me-
tallic salts. With recently precipitated oxyd of silver, double
decomposition ensues, giving rise to iodid of silver and oxyd
of vinic ammonium: 2NEt4I+Ag90,==2AgI+(NEt4)gO]|;
but as anhydrous lime with water produces a hydrate
(CaH)Oa, so the new oxyd forms with it two equivalents
of a hydrate (NEt4.H)0g, which corresponds to (KH)Og.
It is obtained by evaporation as a very soluble, deliquescent
substance, alkaline and corrosive like hydrate of potash,
which it closely resembles in its chemical reactions. As we
have supposed ammonia to unite with water and form a
hydroxyd of ammonium, so in this compound the trivinio
ammonia is united with vinic water or alcohol. The aqueous
compound of ammonia is readily decomposed by heat; and
in like manner, if the new oxyd is exposed to the heat
of boiling water, it is decomposed into trivinio ammonia,
and alcohol, which latter breaks up into olefiant gas and
water j C4H4+H,0r
780. The methylic compound is quite similar to the last
When the hydriodic ether of methol is digested with ammo-
nia, the hydriodate of methamine is for the most part trans-
formed into the iodid of ammonium, and the iodid of methio
ammonium; 4N(H8Me)I=3NH4I + N(Me4)I. The new
iodid forms sparingly soluble crystals, which yield a hy-
droxyd very alkaline and caustic.
The amy lie and complex ammonium salts are analogous in
their characters. Ethamine and methamine have been obtained
by several other processes, and are found in the products of
animal decomposition.
781. By the action of an alloy of potassium and antimony
upon the hydriodic ethers, compounds are obtained represent*
ing ammonias, in whioh antimony replaces nitrogen, (645.)
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ALKALOIDS OF THE ALCOHOL SERIES. 451
They are SbMe3=SbC0Hg and SbEt3=SbC13H15. By
oxydizing agents they lose Ha, and the resulting compounds
constitute alkaloids which form a class of salts.
Stibethic ammonia unites with hydriodic ether to form
SbEt4.I, analogous to the nitrogen compound, and this, with
oxyd of silver, yields a hydroxyd which is a strongly alka-
line base. In like manner, SbMe4l and Sb(MeaEt)I may be
obtained ; all corresponding to the iodids or ammonium and
potassium. The action of chlorine or nitric acid upon sti-
bethic ammonia removes Ha and gives rise to salts of a new
alkaloid SbC^H^, which is called stibethine.
782. When a mixture of acetate of potash and arsenious
acid is distilled at a low red heat, there is obtained, among
other products, a volatile liquid, somewhat soluble in water,
to which the name of alkarsine has been given. It is an
organic base, related to those just described, in which arsenic
replaces nitrogen. It contains C8HiaAsa0a, and corresponds
to the oxyd of an arsenic ethamine, from which Ha has been
eliminated, as in stibethine ; As(EtHa) = AsC4H7 — Ha = As
C4H5, which combines with chlorohydric acid like ammonia:
the anhydrous oxyd (AsCaHs)3.Ha0a=(AsCaHfl)a0a is al-
karsine, or oxyd of arsinum. With chlorohydric acid it yields
a liquid chlorid (AsCaHfl)Cl, to which the name of cMorarsine,
or chlorohydrate o/arsine, has been given. It is a true salt,
like chlorid of ammonium, and by double decomposition yields
different salts, which are also formed by the action of acids
upon alkarsine. The chlorid is decomposed by metallic zinc;
chlorid of zinc is formed, and the organic elements are set
free ; but two equivalents of arsinum unite to form a com-
pound, which is CgH^ASj^ (AsCaH6)a. It is a compound
quasi-metal, and corresponds to Zna aud Ha. It combines
directly with chlorine to form anew the chlorid ; like alkar-
sine, it is a volatile liquid, which, when exposed to the air,
fumes and takes fire even at the ordinary temperature. All
of these compounds have a disgusting odor, and are fear-
fully poisonous. The oxyd, alkarsine, is like an alkali, acrid
and corrosive. M. Bunsen, to whom we are indebted for a
knowledge of these bodies,, gave to the compound quasi-
metal the name of Icalcodyl, (from kakos, evil, and hulc,
principle.)
783. When kakodyl is covered with water, it slowly ab-
sorbs oxygen from the air and yields alkarsine : if to the
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452 ORGANIC CHEMISTRY.
alkarsine/oxyd of mercury is added underwater, the metallic
oxyd is reduced, and a new compound remains in solution,
formed by the oxydation of the alkaloid arsine, which com-
bines with the oxygen and forms AsC4H504, which is the
formula of the new body, alkargen. The solution yields
by evaporation large rhombic prisms of the new substance,
which is inodorous, has but little taste, and is not at all
poisonous. Deoxydizing agents, like sulphurous acid, converts
it into alkarsine. Alkargen combines with acids to form
crystalline compounds like arsine; but by its combination
with oxygen the alkaloid seems to have become more feebly
basic than before ; as in ammonia, one atom of hydrogen in
alkargen or its salts is replaceable by a metal, so that we
may have a compound like AsC4(H4Cu)04.HCl, or chloro-
hydrate of cupric alkargen. By the action of sulphuretted
hydrogen, the oxygen in this alkaloid is replaced by sulphur,
and crystals obtained which are AsC4H5S4.
784. Succeeding the alcohols and their derivations may
be considered a class of volatile liquids, many of them essential
oils, which have analogies with alcohols or aldehyds, although
not homologous with the preceding series. We shall men-
tion briefly some of the more important. Their history is
now nearly as complete as the alcohols, and scarcely less in-
teresting, but the limits of this work will not permit us to
speak of them at length.
Bitter-Almond Oil, C14Hfl0a.
785. BenzoHolf Essential Oil of Bitter Almonds. — This
oil does not exist ready formed in the almonds, but is pro-
duced by the reaction of certain principles contained in the
kernel, when aided by the presence of water. It is obtained
by bruising bitter almonds into a paste with water, and dis-
tilling the mixture, when the oil passes over, with hydro-
cyanic acid and other impurities. It is purified by redistil-
ling it from a mixture of protochlorid of iron and lime, and
is a colorless oily liquid, of a pungent burning taste, and
very fragrant odor, like that of bruised bitter almonds. It
boils at 356°, but its vapor distils over with that of water
at 212° : its specific gravity is 1-073. It is often used in
flavoring articles of food, but the crude oil which is sold for
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BENZOILOL. 453
this purpose is exceedingly poisonous ; the pure oil is com-
paratively harmless.
By the action of hydrosulphuret of ammonia upon bit-
ter-almond oil9 its oxygen is replaced by sulphur, and an
insoluble powder is obtained of the formula C14H6Sa. Its
decomposition by heat gives rise to a variety of new and
curjous products.
786. Chlorinized Benzoilol, C14H5C10a. — This is obtained
by the action of dry chlorine gas upon the oil of bitter
almonds. It is a colorless liquid, which is decomposed by
alkalies, yielding a'chlorid and a benzoate. By distilling
this with bromid or iodid of potassium, similar compounds
are obtained, in which bromine or iodine replaces an equiva-
lent of hydrogen.
The action of dry ammonia upon the chlorinized ben*
soilol yields chlorohydric acid, and a new substance, benza-
mid, C14H5C10a+NH8 = C14H7N03+HCl. It is soluble
in water, and crystallizes in beautiful prisms.
787. Bydrobenzamid. — When bitter-almond oil is placed
in a concentrated solution of ammonia, it is gradually con-
verted into a white crystalline mass of this substance. It
is formed from three equivalents of benzoilol and two of
ammonia by the abstraction of the elements of three
equivalents of water; 3(C14HflOa)+2NH8 = C^HJCT. +
3HaOa. In this reaction the ammonia loses the whole of
its hydrogen, which unites with the oxygen of the oil, and
the residue (Na) is substituted for 06. By the action of
chlorohydric acid it takes up the elements of water, and
regenerates the oil and ammonia ; the latter combines
with the acid to form sal-ammoniac. When boiled in
a solution of potash, it is converted into a metamerio
modification, which is no longer decomposed by acids, but
unites directly with them and neutralizes them. This
substance, which is an alkaloid, is also formed when ammo-
nia is passed through an alcoholic solution of the oil of
bitter almonds ; it is called benzoline or amarine.
When the crude oil of bitter almonds is mixed with an
alcoholic solution of potash, it is gradually converted into a
white crystalline substancej which is called benzoine. It is
polymeric of the oil, and is formed by the union of two
equivalents of it; its formula is consequently Ca8Hia04.
When the vapor of benzoine is passed through a red-hot
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454 ORGANIC CHEMISTRY.
tube, it is reconverted into bitter-almond oil. By the action of
chlorine upon fused benzoine, Hf is removed in the form of
2HC1, and a crystalline compound remains, which is called
benzile, and is C8gH1004.
788. When bitter-almond oil is exposed to the air, it
rapidly absorbs oxygen, and is converted into a white crys-
talline substance, which is benzoic acid; this is formed by
the combination of two atoms of oxygen ; the oil is the
aldehyd of the acid. The same effect is produced when
the oil is heated with hydrate of potash ; hydrogen gas is
evolved, and benzoate of potash formed. A more abun-
dant source of benzoic acid is found in benzoin, a fragrant
resinous substance which is obtained from the Lauras ben-
zoin. This contains a large quantity of the acid, which
may be procured by exposure to a gentle heat, when the acid
is volatilized, and condenses as a white sublimate. It is
also obtained by boiling the benzoin with lime, which forms
benzoate of lime ; chlorohydric acid added to the previously
concentrated solution, precipitates the pure acid in crystal-
line plates. Benzoic acid forms light silky crystals of a
pearly whiteness, and has a pleasant aromatic taste, very
slightly acid. When pure it is inodorous, but generally
has a little volatile oil adhering to it, which gives it a fra-
grant odor, like vanilla. It is volatile at a gentle heat, evolving
a suffocating vapor, which condenses unchanged. It is very
slightly soluble in cold, but more easily in hot water.
The formula of benzoic acid is C14H604 : it is monoba-
sic, and forms a large class of salts, which are of but little
importance. The benzoic vinic ether is obtained by pass-
ing chlorohydric acid gas through an alcoholic solution of
benzoic acid, and is C14(H5Et)04 = C18H1004. It is a fra-
grant volatile liquid, which in its chemical reactions resem-
bles the other ethers ; with ammonia, it affords benzamid
and alcohol. Benzamid is the amid of benzoic acid, and
with H20a yields benzoic acid and ammonia. It is vola-
tile, but at a high temperature loses a second equivalent of
H2Oa and becomes C14H5N. This is a liquid to which the
name of benzonitryl is given ; with 2Hfl03 it regenerates
benzoic acid and ammonia.
With strong nitric acid, benzoic acid yields a crystalline
compound, with the elimination of H3Oa ; it is the nitro-
benzoic acid which has already been alluded to, (652,) and
from its mode of formation is monobasic. When heated
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PHENOL. 455
with a mixture of nitric and sulphuric acids, a second
equivalent of nitric acid is fixed, and binitrobenzoic acid is
formed.
The atom of hydrogen in each case is eliminated from
the nitric acid, and its saline capacity destroyed, but the
benzoic elements still retain the original atom of H,
replaceable by a metal, and thus each of the new acids is
monobasic. The decompositions of the ethers and amids
of these acids yield a variety of curious compounds.
789. Benzen. — The vapor of benzoic acid passed through
a red-hot gun-barrel, is decomposed into carbonic acid and a
new substance named benzen, benzol, or phene, which is
C^Hg. G^Kfi^^Gfi^+G^B.^ Benzen is more easily
obtained by distilling benzoic acid with slaked lime, which
combines with the carbonic acid. It is a colorless, fragrant
liquid, which boils at 187°, and has a specific gravity of
•830 ; at .32° F. it forms a white crystalline mass. Ben-
zen is formed when the fat oils are decomposed at a red
heat, and is obtained in the manufacture of oil-gas for illu-
mination. With fuming sulphuric acid, benzen yields a
monobasic acid, the sulphobenzenic, and a neutral crystalline
body, sulphobenzid. They are analogous to sulphovinic acid
and sulphuric ether.
The phenic alcohol or phenol C19H6Oa is obtained by the
decomposition of salicylic acid, which contains two atoms
more of oxygen than benzoic acid. The name of carbolic
acid is also given to it, and it occurs as a natural product
in the secretion of the beaver, called castoreum, which owes
its peculiar odot and probably its medicinal properties to a
small portion of phenol ; it is also contained in the oil of
coal-tar. Phenol forms colorless crystals, which are liqui-
fied by moisture, although but slightly soluble in water.
Its aqueous solution has an acrid taste, and an odor like
wood-smoke or creasote, which it also resembles in being
poisonous, and a powerful antiseptic. Kreasote is probably
an homologue of phenol.
790. The derivatives of phene and phenol may be repre-
sented as compounds in which C13H5 replaces H, precisely
as the group C4H5 in those of vinic alcohol. With sulphu-
ric acid, phenol yields phenosulphuric acid S^C^Hg.HJOg*
That formed by benzen is Sa(CiaHs.H)Oe, and is pheno-
sulphurous acid: sulphurous acid, 2(SOaHO) = SaHaO0.
With nitric acid, phenol yields three successive products, in
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456 ORGANIC CHEMISTRY.
which one, two, and three equivalents of N04 may oe ra*
presented as replacing hydrogen. The view of the con-
stitution of such bodies, given under nitrobenzoic acid, is,
However, to be preferred. Phenol has, like ateohol, an
atom of hydrogen, replaceable by a metal, and all these
derived compounds have acid characters and are mono-
basic. The trinitric phenol is interesting as the final re-
sult of the action of nitric acid upon many organic sub-
stances, and has been described under the names of picric,
nitropicric, carbazotic, and nitrophenisic acids. It is
ClfH8(N04)809=C19H8N8014, and forms yellowish-white
crystalline scales, which dissolve in a large quantity of
water, yielding a deep-yellow solution, with an intensely
bitter taste. Its salts are yellow, and explode when heated
That of potash Cla(HaK)N8014 is a crystalline salt, very
sparingly soluble in water.
791. The action of nitric acid upon benzen yields a dense
oily liquid, which has a very sweet taste, and an odor like the
essence of bitter almonds, for which it is substituted in per-
fumery. It contains CiaH5N04, and, by the further action
of a mixture of nitric and sulphuric acid, fixes a second
equivalent of the nitrous elements, and yields 0JJ3.Jf908.
Nitrobenzen is to nitrophenol what nitrous ether is to nitric
ether, and is the nitrous ether of phenol, or N(C13H5)04 =
ClaH5N04, and the second product may be regarded as
N(ClaH5.N04)04, still corresponding to N(H)04.
792. Phenol combines with ammonia and forms ClsH609,
NH8. When this compound is heated in a sealed tube, it
is converted into water, and a new alkaloid: ClaH8Oa-f-
NH8 = HaOa-|-C19H7N. This is an ammonia in which
ClaH5 replaces H, and is N(CiaH5.Ha). The same group
may replace an atom of hydrogen in the alcohol-ammonias,
and mixed ammonias containing the different alcoholic and
phenio carbohydrogens, are thus obtained. Td this new
alkaloid the name of aniline is given : it is a colorless, oily
liquid, with a pleasant vinous odor, a burning taste, and is
poisonous : it boils at 328°, and has a specific gravity of
1-028. Aniline is slightly soluble in water ; it decomposes
metallic solutions, and with acids acts the part of a strong
alkali, forming crystalline salts. These salts by heat yield
compounds analogous to the amids, which are called anilids.
They are amids in which ClaHs replaces H. The presenco
of aniline is readily detected by a solution of hypochlorite
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ANILINE. 457
of lime or bleaching-powder, which produces a beautiful
violet-blue with a solution of the alkaloid. It occurs as a
product of the destructive distillation of many organic
matters, and is associated with phenol in coal-tar;
When an alcoholic solution of nitrobenzen is mixed
with sulphuric acid and a fragment of zinc, the hydrogen
evolved by the decomposition of the acid reacts with the
nitrobenzen to form aniline and water, Cj^I^NO^SHj, ==
ClsII7N-|-2H9Ofl. Sulphuretted hydrogen produces a similar
effect, sulphur being separated. When binitrio benzen is
thus treated, an alkaloid is obtained, which is nitric aniline,
in which one equivalent of the nitric elements enters
into the alkaloid -} it is Cl2HflfN04)N.
By indirect processes, alkaloids are obtained which corre-
spond to aniline, in which H and Hs are replaced by chlorine
and bromine. Their basic powers are less strong than the
normal aniline, and the trichloric species CiaH4ClgN is no
longer an alkaloid. When by double decomposition we
endeavor to obtain a hyponitrite of aniline, the salt is at
once decomposed into phenol, nitrogen gas, and water,
C^N+NHO^C^H^+H^+N,.
793. When benzoate of lime is submitted to distillation,
the principal product is a body corresponding to the aceton
of acetic acid ; two equivalents of benzoate 2C14(H5Ca)04=
Cjfi*SiO9-{-Ca6H.10Oa. The new compound is fusible, volatile,
and crystallizes in large prisms, which are soluble in alco-
hol and ether ; fused with hydrate of potash, it is decom-
posed into benzoate and benzen, Cfl6H10Oa-(-(KH)Os=
C14(H5K)04-(-ClflH8. From this relation to benzoates and
benzen or phene, it has received the name of benzophenon :
with chemical agents it affords several new and curious
compounds.
Benzoiloi is one of a group of aldehyds which are repre-
sented by the general formula CBHll_80a, and yield volatile
monobasic acids with 04, decomposable into Ca04 and car-
bohydrogens C^H^g, which form alkaloids CnH„_5N. The
essence of the seeds of cumin ( Cuminum cyminuni) consists
of such an aldehyd, cuminol C^H^Og, and a carbohydrogen
homologous with benzen, cymen C^H^. The distillation
of cuminic acid with baryta affords another homologue, cu-
men C^H^. This with strong nitric acid yields nitro-
cumen, but, by long boiling with dilute acid, it is converted
into benzoic acid In the same way cymen gives rise to a
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458 ORGANIC CHEMISTRY.
new acid, called lolxdlc acid, which is C16H?04, and homo*
logons with benzoic and cuminio acids ; with baryta it yields
toluen CMH8, which is also obtained by the distillation of
tolu balsam. Alkaloids homologous with aniline have been
formed from all these hydrocarbons. The action of nitric
acid upon benzen has failed to yield an acid lower in the
series than the benzoic.
Phenol belongs to another group of what may be termed
alcohols, which are represented by the general formula
C^H^^Og. There is still another class of aldehyds, repre-
sented by CnH(l_s04, which are consequently metameric with
the acids of the benzoic group, and which form acid with Og.
Such is talicylol, the essential oil of Spirea tUmaria, (queen
of the meadow.)
Salicylol, C14Ha04.
794. This is obtained by distilling the flowers of spirea
with water ; the oil does not pre-exist in the plant, but is
formed during the process, like benzoilol, by the reaction of
?rinciples in the plant which have not yet been examined,
t may also be formed from salicim, a vegetable principle ex-
tracted from several species of Salix, to which both substances
owe their name. Salicylol is a colorless liquid, heavier than
water, in which it is somewhat soluble, and has the fragrant
odor which is perceived when the flowers of spirea are bruised.
Its composition C14Hfl04 is identical with that of benzoic
acid. One atom of hydrogen in it may be replaced by
chlorine or bromine, and an atom of hydrogen is also re-
placeable by a metal yielding compounds like C14H6K04.
It forms a crystalline compound with ammonia, which soon
changes into an amid like hydrobenzamid.
Heated with hydrate of potash, hydrogen is evolved and
a salt of salicylic acid is formed. The acid is C14He04. It
crystallizes in delicate white prisms, and is volatile and
sparingly soluble in water. Salicylic acid is monobasic,
and has considerable resemblance to the benzoic ; it forms
a coupled acid with nitric acid.
795. The ethers of salicylic acid are easily formed : that
of methol is interesting, because it constitutes the principal
part of the fragrant essential oil of winter-green, Gaultheria
(trocumbens, obtained by distilling that plant with water.
The ether is readily decomposed by an alcoholic solution
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of hydrate of potash, and yields wood-spirit and salicylate
of potash. If to the hot solution of the salt an excess of
chlorohydric acid is added, the salicylic acid crystallizes on
cooling. Ammonia converts the ether into a crystalline
mass of salicylamidy which has the composition of salicylate
of ammonia minus Hs09.
When the salicylic acid is rapidly distilled, it is decomposed
into carbonic acid and phenol C14H604 = Gfi^G^fi^
If strong nitric acid is added to the oil of winter-green or
salicylic acid, and the mixture boiled so long as red vapors
appear, a large quantity of trinitric phenol, nitropicric acid,
is obtained on cooling.
The essences of anise, fennel, and some other plants, con-
sist principally of an oil, to which the name of a/nethd has
been given. It is C^H^CX, : by oxydizing agents, such as
nitric acid, it is converted into oxalic acid, and a new acid
resembling the salicylic and homologous with it, which is
called anisic acid C16H8Oe. Its decomposition yields car-
bonic acid and anisol O^HgOg, a homologue of phenol.
Other Essential Oils.
796. The essences just described are types of a large
number of essential oils, which, although not all homologous
with the classes named, sustain the relation of aldehyds or
alcohols to corresponding acids. Such is the oil of cinna-
mon, which is CjgHgOj,, and yields by oxydation cinnamic
acid C18H804. This acid is associated with the benzoic,
which it resembles, in its properties, in the balsam of tolu :
by nitric acid it is oxydized and yields benzoic acid. When
distilled with baryta it is decomposed into carbonic acid and
a carbohydrogen, cinnamen ClflH8.
Both cinnamol and cinnamen appear to exist in the bal-
sams, such as styrax, benzoin, tolu, and the balsam of Peru.
These consist of resinous matters, apparently formed by the
oxydation of essential oils, and mixed with cinnamic or
benzoic acids, or with both.
797. The oxygenized essences already described are, as in
the case of cuminal, often associated with other oils, which,
like cymen, contain no oxygen, and these carbohydrogen oils
sometimes constitute the only product of the distillation.
The most important of this class has the formula O^H^
and is best known under the form of oil of twpentine. It
is obtained by distillation from the crude turpentine which
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460 ORGANIC CHEMISTRY.
exudes from many species of Pinus, and is a mixture of the
volatile oil and a resin. Its taste and odor are well known ;
it has a specific gravity of *865, and boils at 312°. It is
insoluble in water, but soluble in alcohol. Oil of turpentine
is of great use in the arts, for the preparation of varnishes
and paints, and is used for illumination, under the names of
camphene and pine-oil. The liquids sold for the same pur-
pose, under the names of burning-fluid and spirit-gas, are
solutions of camphene in highly rectified alcohol, and, from
their great volatility and inflammability, are very liable to
explosion and dangerous accidents.
798. The oils of juniper, pepper, caraway, parsley, citron,
lemon, orange, and bergamot are carbohydrogens, identical in
composition, density, and boiling point with oil of turpentine,
and may be included under the general name of camphen.
They absorb chlorohydric acid gas, and yield a crystalline
compound, which is C^H^. HC1 == C^H^Cl, and has all the
characters of a substitution product from C^H^. The liquid
portion of the oil which has been treated with the gas has
the same composition as the solid. This is crystalline
and volatile, and has an odor like ordinary camphor. The
essence of citron, unlike the others, fixes 2HC1, and yields
a compound C^H^Cl^ These chlorinized bodies are decom-
posed when distilled with lime, and yield modifications of
camphen, distinguishable principally by their odors and
their different action upon polarized light.
799. When moist oil of turpentine is exposed to cold, it
often deposits a crystalline compound : a similar substance
is slowly separated from a mixture of the oil with alcohol
and nitric acid. It crystallizes in beautiful prisms, and is
volatile, very soluble in alcohol, and sparingly soluble in
water. The composition of this new body is represented
by C^H^O^ and it is therefore formed by the fixation of
2HaOa; it crystallizes with an additional equivalent of
water, which is expelled by heat: the name of terebol is
given to it. When dissolved by boiling, in water acidulated
with sulphuric or chlorohydric acid, it is completely decom-
posed into water and a volatile liquid, terpinol, which is
obtained by distillation and has an odor of hyacinths : it is
C^HjiA. Chlorohydric acid gas expels water from fused
terebol, and yields CaoH18Cla, a crystalline body identical in
composition with that obtained from lemon camphen.
The odors of these different varieties of the same carbo
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ESSENTIAL OILS. 461
hydrogen depend upon differences in constitution not yet
understood; they are apparently independent of the pre-
sence of any oxygenized compound, as the different essences
may be distilled from hydrate of potash or potassium, with
no other effect than that of refining their odors. The oil of
roses is a carbohydrogen of different composition, probably
800. Many of the oxygenated volatile oils deposit, by
cold, crystalline compounds which are often isomeric with
the oils themselves, and are distinguished by the general
name of stearoptens, or camphors of their respective oils, from
their resemblance to common camphor. This substance is
obtained by distilling the wood of the Lauras camphara with
water, and is crystalline, very volatile, fragrant, and soluble
in alcohol, but insoluble in water. Its formula is C^H^O^;
heated with hydrate of potash under pressure, it combines
directly with it and forms a salt, campholate of potash
GW(H17K)CL With strong nitric acid it yields camphoric
acid CaoH^Og, which is bibasic.
801. The Drybalanops camphor a of Borneo yields a solid
fragrant essence, which is known as Borneo camphor, and is
much valued in the East : it also exists in the essential oil of
valerian. This camphor has the formula C^RJO^, and, whea
heated with nitric acid, loses Ha and yields laurel camphor.
When distilled with anhydrous phosphoric acid, it yields a
form of camphen which exists with the camphor in the
plant, and fixes H90s to form it. When laurel camphor is
thus distilled, a carbohydrogen C^H^ is obtained, which is
cymen.
802. The essential oil of black mustard-seed Sinapis nigra,
is obtained by distilling the bruised seeds with water. It
is heavier than water, pungent and acrid, and contains
sulphur. It is represented by the formula CgH^S,. With
ammonia it combines and forms a crystalline alkaloid, thiosi-
namine CsH8NaSa, which, when heated with oxyd of lead,
loses HflSfl and forms sulphuret of lead and water, together
with a new alkaloid C8H8Nfl, called sinamine, which is crys-
talline^ and is a strong base.
The essential oil of horse-radish, Cockkaria officinalis, is
identical with that of mustard. The oil of asafoetida con
tains carbon, hydrogen, and sulphur : it is probably C^H^S. ,
and seems allied to a sulphuretted ether or alcohol : with
chlorid of mercury it forms a crystalline compound which
Digitized
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462 ORGANIC CHIMI8TBY.
contains the elements of the oil with those of the mercurial
salt. When mixed with sulphocyanid of potassium, a
decomposition ensues which gives rise to the essential oil of
mustard. The oil of garlio belongs to the same series, which
is very interesting from its curious and as yet imperfectly
known relations.
The odorous secretion of the polecat, Mephitis putorius,
contains sulphur, and perhaps belongs to the same class.
803. Resins. — These substances are vegetable products,
and seem to have been generally formed by the oxydation
of essential oils ; they are insoluble in water, but soluble in
alcohol and ether, and many of them aie used in pharmacy
and in the arts. Among them are copal, mastic, elemi,
guiacum, and colophony or pine resin. In their crude state
they are often mixed with volatile oils, which may be sepa-
rated by distillation with water, as those of turpentine and
elemi, or with soluble acids, like the benzoic and cinnamic,
as in the balsams, and often with gums and other principles
soluble in water, constituting what are called in the materia
medica, yum resins, like asafoetida and gamboge. The
true resins are many of them acids, and form distinct salts
with bases. The resin of the pine may be obtained by care-
ful management from its alcoholic solution, in crystalline
crusts, very soluble in ether and sparingly soluble in alcohol.
Exposed to heat, it distils over and condenses in an isomeric
modification, distinguished in its crystallization and solu-
bility. Under certain circumstances, both varieties may
be converted into an amorphous form. They have been
denominated pimaric and sylvic acids, and are both mono-
basic, and represented by C^H^O^ Two equivalents of
oil of turpentine and 06, yield Hfl09 and an equivalent of
pimaric acid. The resins of copaiva, elemi, and anime be-
long to one or another of the modifications of this acid.
804. Caoutchouc, Gum-Elastic. — This curious substance is
found in the juices of many plants, but is principally obtained
from the Hevea guianesis, and latropha elastica. Its ordi-
nary properties are well known : it is insoluble in water and
alcohol, but dissolves in ether and many volatile hydrocar-
bons : when softened by these solvents, it is wrought into
a great variety of curious and useful articles. Small tubes
of gum-elastic are very useful in the laboratory, to join
glass tubes and form flexible joints. They are easily made
from sheet caoutchouc by cutting the folded edges of the
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VEGETAL ACIDS. 468
sheet with clean
scissors over a glass
tube, as seen in
figure 417. Caout-
chouc is very com-
bustible, and burns
with a bright smoky
flame. It contains Kg. -417.
carbon and hydrogen only, and probably in equal equivalents;
but it furnishes no reactions by which we may fix its formula or
even determine whether it is chemically homogeneous. When
exposed to heat it is decomposed, and yields several volatile
hydrocarbons homologous with olefiant gas : among them
are said to be C8H8, C10H10, and C^H^. These mixed
liquids are used as a solvent for caoutchouc ; the volatile
oils from coal-tar are also employed for the same purpose.
When caoutchouc is immersed in a bath of melted sulphur,
or when sulphur is added to its substance and the mate-
rial afterward exposed to a considerable heat, (280°,) the
caoutchouc undergoes a peculiar change. It becomes much
firmer and stronger, and less liable to be softened by heat or
rendered rigid by cold ; in this form it is known as vulcanized
gum-elastic, and is extensively used in the arts, in preference
to the unaltered caoutchouc. This is Goodyear' s patent.
805. Gutta Percha. — This substance exudes from the
Lonandra gutta, a tree common in the Malaccan peninsula,
and forms a tough and elastic mass at ordinary temperatures,
which becomes ductile and plastic when warmed by immer-
sion in hot water. Gutta percha (pronounced pertcha) is
a mixture of several resins, which are separable frpjpa each
other by means of their different solubility in alcohol and
ether. The greater portion of it consists of a resin which
softens at 104° F., and is but little soluble in cold ether
when pure. It contains a greater amount of oxygen than
pimaric acid. Gutta percha is readily dissolved by chloro-
form and sulphuret of carbon, which deposit it unchanged
by evaporation. It is capable of being moulded into a great
many articles of utility and ornament.
VEGETAL ACIDS.
806. Besides the acids which we have described as derived
from bodies of the alcohol group, or from the various essen-
tial oils, and which are generally monobasic, volatile, and,
Digitized
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4&4 ORGANIC CHEMISTRY.
when of high equivalents, sparingly soluble in water, there
remains to be described a class of acids of high equivalents,
which are bibasic or tribasic, very soluble in water, and
contain a large amount of oxygen, having analogies with the
lactic acid. Such are the oxalic, citric, tartaric, and malic
acids, and some others of less consequence.
807 Oxalic Acid, C4Ha08.— The salts of this acid exist
in many vegetables : the agreeably sour taste of the wood-
sorrel, Oxalis acetosdla, of the common sorrel, a species of
Rumexy and many other plants, is due to the acid oxalate of
potash which they contain, and from which the acid may be
extracted. It is also a product of the action of nitric acid
upon alcohol, upon sugar, starch, lignin, and many other
organic substances. To prepare it, one part of sugar is heated
with eight parts of nitric acid, specific gravity 1-25. A
violent action ensues, and much nitrous acid is evolved;
when this ceases, the solution is concentrated by evaporation,
and on cooling yields a large quantity of crystals of oxalic
acid, which are purified by washing in a little cold water
and recrystalliiation.
808. Oxalic acid forms colorless* crystals, which are
C4H808-f-2H808 ; by a gentle heat the water is expelled,
and the dry acid remains as a white powder, which, at a
higher temperature, is in part sublimed unchanged, and
partly decomposed into formic acid, water, carbonic acid
and carbonic oxyd gases. The acid is very soluble in water,
has a strongly acid taste, and is poisonous. When the acid
or one of its salts is heated with strong sulphuric acid, it
is decomposed without blackening, a character by which it
is distinguished from the succeeding acids, and evolves
equal volumes of carbonic acid and carbonic oxyd gase3 ;
C4H90.= C?04+C,0,+H„0s.
Oxalic acid is bibasic; the neutral oxalate of potash
is a very soluble salt, and is C4(K8)08 ; the acid oxalate
C4(KH)08 is less soluble, and has a pleasant acid taste. It
is known under the name of binoxalate, and as it was for-
merly obtained from the wood-sorrel, is often sold as salt
of sorrel, for the purpose of removing iron-stains from linen,
which it does by forming a soluble salt with the iron oxyd.
The acid oxalate crystallizes with another equivalent of
oxalic acid to form a salt which is called a quadroxalate,
and contains C4Ha08-|-C4(HK)08, or one-fourth the amount
tf potash that is in the neutral oxalate. The acid might
Digitized
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OXALIC ACID. 46t>
hence be regarded as quadribasic, and be 08H4O16, but its
other reactions lead to the conclusion that it is properly
bibasic. The second equivalent of acid may be regarded
as holding a place analogous to that of the crystal- water in
other salts. The oxalate of ammonia C4(NH4)a08 crystal-
lizes in fine prisms; when decomposed by heat it loses
2HaOa, and yields the amid of oxalic acid, ozamid, which
is C4H4Na04. It is a neutral insoluble body, and by the
action of acids is reconverted into oxalate. The acid oxa-
late of ammonia yields in like manner an acid amid, oxa-
mic acid, C4H,09+NH, = C4HsN08-Ha09 = C4HsN08.
It is monobasic, and forms a series of salts : when its solution
is boiled it is changed into acid oxalate of ammonia.
The oxalate of lime crystallizes with 2H303 ; it is a very
insoluble salt, and occupies an important part
in the vegetable economy, being secreted by
a large number of plants, in the cells of which
the microscope reveals a great number of
beautiful crystals of this substance; this
appearance is represented in figure 418, of a
vessel from the bark of Torreya taxifolia.
In many of the lichens, the oxalate of lime _
appears to replace the woody fibre, and to be m&- -us.
somewhat allied in its functions to the carbonates and phos-
phates of lime in the animal kingdom. The oxalates of the
metals are generally insoluble.
With two equivalents of the alcohols, oxalic acid forms
neutral ethers ; and with one, vinic acids. The oxalic ether
of wood-spirit is obtained in fine crystals ; it is C4(Mea)0s :
mixed ethers of £he different alcohols may be obtained, such
as C4(EtMe)08. When ammonia in excess is added to
oxalic ether, oxamid is obtained; but if the ammonia is
cautiously added, a beautiful crystalline substance is formed,
which is named oxamethane, and regenerates an oxalate,
alcohol and ammonia, by fixing 2HaOa. It corresponds to
sulpharyethane, and is at once the amid of oxalovinic acid,
and the ether of oxamic acid. Oxalic acid pertains to the
series already described under oleic acid, including succinic
and suberic acids, and represented by CnH^gOg > when fused
with hydrate of potash it yields a formate.
809. Tartaric Acid, CsH6Ola. — This acid exists in the
juices of many fruits, particularly that of the grape, as an acid
tartrate of potash. As this salt is almost insoluble in dilute
Sti
Digitized
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466 ORGANIC CHEMISTRY.
alcohol, it is deposited, during the fermentation of wine, in
crystalline crusts, known as crude tartar, or argol. It is
decomposed by chalk to form a tartrate of lime; this is
mixed with an equivalent of sulphuric acid, which forms a
sulphate, and liberates the tartaric acid. From a concen-
trated solution it crystallizes in fine rhombic prisms, very
soluble in water and alcohol, and having a pleasant acid
taste. Tartaric acid is bibasie. The acid tartrate of potash
C1(H5K)0ia is prepared by refining the crude tartar by
crystallization, and generally appears as a crystalline powder,
sparingly soluble in water, and feebly acid to the taste. It
is known in pharmacy as cream of tartar. The neutral
tartrate is mu h more soluble in water, and is commonly
called soluble tartar. It is Ca(H4Ks)0la. By saturating
cream of tartar with carbonate of soda, a double salt is ob-
tained which is C1(H4KNa)0ta : it forms very large transpa-
rent prismatic crystals, and is known as RocheUe salt.
810. When cream of tartar and oxyd of antimony are
boiled together in water, solution takes place, and, on. cool-
ins, transparent crystals of a double salt are deposited, which
is Known in medicine by the name of tartar emetic.
The part which the oxyd of antimony plays in this com-
pound is peculiar. We may represent two equivalents of
oxyd of antimony 2Sb08=Sb9Ofl as (SbO^O^, correspond-
ing to H30fl, and the group SbOa will then be equivalent to
H, and may replace it in combination. The salt in ques-
tion is such a compound, and the acid tartrate being
OfiJ[HKyOw tartar emetic dried at 212° is C8H4(SbOfl.K)
0o. The crystals at the ordinary temperature contain Ha08
as water of crystallization, but lose it by a gentle heat. If
the dried salt is heated to 428°, it breaks up into water
H808, and a salt which is C8Hfl(SbK)019 : in this compound
antimony in one-third its ordinary equivalent may be sup-
posed to replace hydrogen as in the analogous compounds of
the sesqui-oxyds : if we call this Sbt, stibicum, and repre-
sent it by sb, the dried salt then becomes C8H9(sb-K)0j.:
it is then, however, quadribasic. Oxyd of uranium U08
may in the same way replace H in a tartrate, and by heat
Ut, corresponding to sb, and represented by ur may be
obtained in combination, replacing H : in this way all the
hydrogen is removed and a compound obtained which is
C8(ur8sb8)0ir Arsenious acid AsOa and boracic acid BoQ,
Digitized
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VEGETAL ACIDS. 467
afford, with bitartrate of potash, compounds analogous to
these salts of oxyd of antimony.
Tartaric acid dissolves peroxyd of iron and forms a very
soluble salt : in this, as in the preceding compounds, the
metal is not precipitated by solutions of potash or ammonia.
The decomposition of tartaric acid by heat produces several
new acids, which have not yet been thoroughly studied.
811. The crude tartar obtained from the wine of the
Vosges some years since, was found to contain an isomeric
modification of tartaric acid, which is less soluble than the
ordinary acid, and crystallizes with an equivalent of water,
while the common form is anhydrous : the new acid precipi-
tates solution of the salts of lime, and in the chemical cha-
racters of several of its salts is distinguished from the ordi-
nary tartaric acid, with which however it is metameric : it
has received the name of racemic acid. The replacements
of the crystals of tartaric acid and of its salts are upon alter-
nate angles, constituting what is called a hemihedral modi-
fication, and the order of the replacements is from left to
right : a solution of tartaric acid or of any tartrate acts
upon polarized light, and causes the ray to rotate in the
same direction. Racemic acid and its salts are not hemi-
hedral, and do not affect iq any way the ray of polarized
light. When, however, a solution of the double racemate of
potash and ammonia is crystallized, two sets of crystals are
obtained in equal quantities : the one are hemihedric to the
right, and identical in all respects with the ordinary tartrate
of these bases : the others have left-handed hemihedrism, and
cause the beam of polarized light to deviate to the left ; and
these two salts contain two tartaric acids which are distinguish-
ed from each other only by their opposite hemihedral modi-
fications and their action upon polarized light. The right-
handed acid is ordinary tartaric acid, and the left-handed a
new and a distinct modification ; and these two are not by
any known means convertible into one another. The forma
of the two crystals are to each other as the image in a mirror
is to the object. When saturated solutions of the two acids
are mixod, they become warm, and deposit crystals of the
racemic acid, in which their mutual influence upon polarized
light is neutralized.
812. Malic Acid, C8H0Olo. — This acid exists in the juices
of many sour fruits, particularly in the apple and the ber-
ries of the mountain ash, Sorbus aucuparia : the stems of p
Digitized
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468 ORGANIC CHEMISTRY.
the garden rhubarb also contain a large quantity of it It
is very soluble in water and alcohol, and crystallizes with
difficulty ; its solution has a pleasant sour taste. The maiio
acid is bibasic, and the malates of the alkaline bases are
very soluble. The acid malate of ammonia C8(H5NH4)0lt
forms large transparent crystals. The neutral malate of
lead Ct(H4Pb8)010 is obtained as a white readily fusible
precipitate, which in an acid liquid slowly changes into
delicate crystals. Malic acid is not volatile, but is decom-
posed by heat into water and new acids, which are described
in the larger works.
813. When tartaric and malic acids are heated with anhy-
drous alcohol, vinic acids are obtained corresponding to the
sulphovinic. The neutral ethers are more difficult of prepa-
ration, as they are soluble in water and not volatile : by
passing hydrochloric acid gas, however, through the alco-
holic solutions of the acids, neutralizing the excess of acid
with carbonate of soda, and agitating the mixture with
hydric ether, the ethers of the acids are dissolved out, and
may be obtained by evaporating the solution at a gentle
heat. They are converted by ammonia into amids and
ethers of araidic acids : in this way tartramic acid and tar-
tramid may be obtained.
814. Malic ether yields malamid, which has the compo-
sition of and appears to be identical with asparagine, a
peculiar nitrogenized principle found in the juices of the
asparagus, mallows, and particularly in the young shoots of
vetches which have vegetated in the dark. It forms large
crystals, sparingly soluble in cold water, and contains
C8H8N906, corresponding to malate of ammonia from which
the elements of water have been abstracted, CsH4(NH4)8010
— 2HaOa=C8H8N908: by the action of alkalies or acids i*
loses ammonia and yields aspartic acid C8H7N08, which is
now found to be identical with malamic acid, and to be
formed from acid malate of ammonia as oxamic acid is from
the acid oxalate.
The ordinary action of acids or alkalies does not further
decompose this acid ; but when nitric oxyd is passed into a
solution of asparagine or aspartic acid in nitric acid, the
hyponitrous acid formed, decomposes the aspartic, yielding
malic acid, nitrogen, and water, by a decomposition similar
to that described under aniline : C8H7N08+NH04== C.H.O*
Digitized
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VEGETAL ACIDS. 469
Citric Acid, C^HgO^. — This acid exists in the juices of
many fruits, often associated with the tartaric and malic,
and is the acid of lemons. It is obtained by saturating
lemon-juice with chalk, by which an insoluble citrate of
lime is formed ; this is decomposed with an equivalent of
sulphuric acid, which forms sulphate of lime, and the citric
acid is obtained by evaporation and crystallization. It forms
large crystals belonging to the trimetric system ; it is very
soluble in water, and has a strong but agreeable acid taste.
The citric acid is tribasic, and forms with potash three salts,
in which one, two and three atoms of hydrogen are replaced
by potassium : the first two salts are acid, and the last, which
is Cu(H5K3)Ou, is neutral. In the same way it yields a
neutral ether with three equivalents of alcohol, and vinio
acids with one and two equivalents.
When exposed to heat, citric acid is decomposed into
HaOa and C13H6Oia ; this is a new acid, which is also found
combined with lime in the Aconitum napellus, and is hence
called aconitic acid; it is tribasic and very soluble in water :
when the action of heat is carried still further, the aconi-
tic acid is decomposed into Ca04 and C10H6O8; this last is
called citraconic acid, and is bi basic, soluble, and by heat
distils in part unchanged : a higher temperature decomposes
it into water, and a neutral liquid C10H4O6. This sub-
stance, which is called citraconid, slowly dissolves in water,
and combines with HaOa to form an acid isomeric with citra-
conic acid.
815. Tannic Acid, Tannin. — Many plants contain a
peculiar principle, characterized by an astringent taste, and
by precipitating animal gelatine from its solutions, forming
r with it an insoluble compound, upon the production of which
depends the prosess of tanning leather. The barks of oak
and hemlock, and gall-nuts, which are excrescences resulting
from the puncture of insects upon the branches of a species
of oak, contain a large portion of this principle, which is
named tannic acid, and are used in the preparation of
leather : they are also employed with persalts of iron in
dyeing black, and in the formation of writing-ink. The
vegetable extracts called kino and catechu, and many other
vegetable substances, contain a principle analogous to the
tannin of the oak. Tannic acid is obtained in a pure state
from gall-nuts, which yield about one-third of their weight,
by the following process : — They are reduced to a coarse pow-
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470 ORGANIC CHEMISTRY.
tier, and placed in the upper part of a vessel like that repre-
sented in the figure, the mouth of which is
previously stopped with a piece of linen, and a
quantity of hydric ether is then poured over them,
which slowly filters through, and collects in
the lower vessel, where it separates into two
layers. Ordinary ether contains about one-
twelfth of water, which dissolves the tannic acid
to the exclusion of all other substances, and
for m8 a solution that does not mix with the ether,
which dissolves a portion of coloring matter from
the gall-nut The dense aqueous solution is
separated, washed with a little ether, and finally
evaporated in shallow vessels by a gentle heat.
It forms a brilliant porous mass, which has gene-
rally a light yellow tint ; it is very soluble in
water and has a purely astringent taste. Sul-
phuric, nitric, chlorohydric and phosphoric acids
givo copious precipitates with its solution, which
g* are combinations of the two acids. The tannic
is a feeble acid, and is bibasic or poly basic. The alkaline tan-
nates are soluble ; those of the metals are generally insoluble,
and often colored. The pertannate of iron is the basis of
black dyes ; and of writing-ink : it is insoluble in water, but
when the solutions are dilute, the precipitate remains a long
time suspended, especially if a little gum is added, as in
the fabrication of ink. When a solution of tannic acid in
potash is heated, a salt of gallic acid is formed, with the
production of a brown matter. Similar results are obtained
when strong acids act upon tannin, and the powder of nut-
galls mixed with water undergoes a sort of fermentation,
which also yields gallic acid. When boiled for some time
with dilute sulphuric acid, tannin is converted into gallic
acid and grape sugar. The brown products obtained with
strong acids and alkalies, result from the decomposition of
the sugar which is produced. The probable formula of
tannic acid is C^H^Oggj tw0 equivalents of it with 6HsOf
yield one of glucose, C^H^O^ and two of gallic acid,
C,4H6010.
Gallic Acid, C14H6010. — This acid exists ready formed
in the seeds of the mango : it is most easily prepared by
the process of fermentation already described ; it is dissolved
out of the mixture by boiling water, and separates on cool-
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VEGETAL ALKALOIDS. 471
fng in small silky crystals, which require 100 parts of cold
water for their solution, add have an acid and astringent
taste. Gallic acid does not precipitate gelatine, and the
black color of the pergallate of iron is destroyed by boil-
ing. Gallic acid is bibasic : its salts have been but little
studied. When carefully heated, it is decomposed into Cf04
and a crystalline sublimate, which is pyrogaUic acid, and is
CMH806. It is very soluble in water and alcohol, and when
dissolved in a solution of hydrate of potash, absorbs oxygen
so rapidly from the air as to be employed in eudiometry.
Both gallic and pyrogallic acids reduce the salts of plati-
num, gold, and silver. An application of this is made for
the purpose of coloring the human hair, which is first wet
with a solution of gallic acid, and then, after drying, moist-
ened with an ammoniacal solution of a salt of silver. The
reduced metal imparts a fine black or brown color to the
hair, which is permanent.
For a large number of other vegetable acids, many of
which are yet but imperfectly known, the student is refer-
red to more extended treatises.
VEGETAL ALKALOIDS.
816. The artificial organic alkaloids which we have de-
scribed under different heads in the preceding pages, have
been considered as derivatives of ammonia in which one or
more atoms of hydrogen are replaced by the elements of
some carburet of hydrogen; such are aniline and metha-
mine. We have pointed out how these, like ammonia, may
fix the elements of water, and form compounds analogous
to hydrate of potash, such as the hydroxyd of vinic ammo-
nium (NEt4.H)0s ; but when these combine with an acid,
the oxygen is eliminated in the equivalent of water which is
formed, and it is but the group NEt4, which replaces hydro-
gen in the acid. There are, however, a large number of
organic bases occurring in different vegetable substances,
which, like aniline and ammonia, combine directly with acids
without the formation of water, and which contain oxygen.
All of these alkaloids contain one and sometimes two atoms
of nitrogen, and may be regarded as derivatives of ammonia
in which the group of elements replacing hydrogen contains
oxygen. They are commonly crystalline and not volatile
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472 ORGANIC CHEMISTRY.
without decomposition, and generally possess active medi-
cinal powers. Those of opium, cinchona, hellebore, and
man j others constitute the active principles of these drags.
When exposed to heat, especially in the presence of caus-
tic alkalies, they are decomposed, and generally evolve
volatile alkaloids without oxygen ; among these, methamine
and aniline are met with. Several other volatile alkaloids
obtained by the action of a solution of hydrate of potash
upon plants, are supposed to be the result of a similar
decomposition.
817. Many of the vegetal alkaloids are strong bases, and
completely neutralize acids ; others are comparatively feeble,
and their salts are even decomposed by a gentle heat.
They combine with chlorid of platinum to form double
salts, which are generally sparingly soluble, and analogous
to the chlorid of platinum and ammonium : some of them
unite with one, and others with two equivalents of the chlo-
rid, and in like manner they frequently form two chloro-
hydrates by fixing one and two equivalents of chlorohydric
acid, thus giving rise to neutral and acid salts. The
alkaloids combine with metallic salts in the same way as
ammonia, and yield compounds with nitric acid, and with
nitrate of silver. They generally form combinations with
chlorid of mercury, which have a similar composition with
the ammonia salts. We shall first describe some of the
more important of the oxygenized alkaloids, and then pro-
ceed to speak of those analogous to aniline.
818. Alkaloids of Cinchona, or Peruvian Bark, — The
barks of several species of cinchona owe their medicinal
properties to the presence of two alkaloids, which are named
quinine and cinchonine. They are extracted by digesting
the bark in a dilute acid, and adding to the infusion a solution
of carbonate of soda, which precipitates the alkaloids in an
impure state. The precipitate is washed * and dissolved in
boiling alcohol ; a little animal charcoal is added to remove
some coloring matter, and the filtered liquid, on cooling,
deposits crystals of cinchonine, while the more soluble
quinine is obtained by evaporation. Quinine is a white crys-
talline substance, sparingly soluble in water, but readily so
in alcohol and ether.
The formula of this alkaloid is C88H3aN304. It is readily
soluble in acids, forming crystallizable salts; which have a very
Digitized
byGoogk
VEGETAL ALKALOIDS. 473
bitter taste. These are two chlorohyd rates, one CggH^NgC^ .
HC1, which if we would compare it with chlorid of ammo*
nia, must be written (C^HggNjjOJCl = QuCl, and a second
acid salt QnCl.HCl, or CJEy^O^HCl ; the platinum
double salt corresponds to this acid chlorohydrate : there
exists, in like manner, two sulphates of quinine, which with
several other salts of this base are employed in medicine.
Cinchonine is represented by CsgH3aNfl03; it differs from
quinine only by 03, and resembles that base in its charac-
ters, but is less soluble in alcohol and ether. Its salts are
similar to those of quinine, and are often substituted for the
latter in medical practice.
819. In the preparation of these alkaloids, a portion of
quinine is often obtained as an uncrystallizable resinous
mass, which is, however, identical in chemical composition
and medicinal properties with the crystalline base. It is
called quinoidine. The cinchona known in commerce as pale
bark contains principally cinchonine ; the yellow bark qui*
nine, and the red bark, a mixture of both. Different varie-
ties of cinchona have furnished two or three other bases very
similar to these ; to which the names of aricinef chinova*
tine, and quinidine have been given.
These bases are accompanied with a peculiar acid, called
quinic or kinic acid ; it forms large crystals resembling tar-
taric acid, and is bi basic : its composition is represented by
C14Hlfl0a2. The results of its decomposition form a very
interesting series.
By the action of chlorine and bromine upon solutions of
chlorohydrate of cinchonine the hydrogen of the alkaloid
is in part replaced, and bichhric and bibromic cinchonine are
obtained ; the former is CggH^CLjNgO,,, and is isomorphous
with the normal alkaloid.
When cinchonine is distilled with hydrate of potash, a
carbonate is formed and hydrogen gas escapes, with a new
volatile base named chinoline or quinoline, which is an oily
liquid and resembles aniline in its properties. Its compo-
sition is represented by C18H7N: CS8HaaNaOfl+2(KH)Ofl =
2CwH;N-|-C3K306-foH3. Quinine and strychnine yield
chinoline by a similar process.
Alkaloids of Opium. — This substance is the inspissated
juice of the capsules of a species of poppy, Papaver somni-
ferum, and contains several organic bases. The most im-
portant of these, and the one to which it owes its power at
Digitized
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474 ORGANIC CHEMI8TBY.
an anodyne, is morphine* It id prepared by precipitating
a solution of op; 1m by carbonate of soda, as in the process
for quinine ; the impure morphine is digested in cold alcohol
to remove some other alkaloids present, and finally dissolved
in dilute acetic acid. The cautious addition of ammonia to
the acetate thus formed, precipitates the morphine, which
is dissolved in hot alcohol, and crystallizes on cooling. It
forms brilliant rectangular prisms, which are sparingly soluble
in water, readily so in hot alcohol, and insoluble in ether;
it has a persistent bitter taste. Its formula is 084H19NO6.
Morphine forms crystalline salts, some of which, as the
chlorohydrate, sulphate, and acetate, are employed in medi-
cine. The best opium contains six or eight per cent, of this
alkaloid.
820. Codeine is a base which occurs in small quantities
with morphine ; it is more soluble in water than that alka-
loid, and dissolves readily in ether : it seems allied to mor-
phine in its effects upon the animal system. The formula
for codeine is 0MHf tNO0. When heated with sulphuric acid,
codeine yields a compound which is derived from the sulphate
by the elimination of 2Ha09, and corresponds to an amid:
morphine and some other alkaloids yield similar compounds.
Bases have been obtained from it in whioh portions of the
hydrogen are replaced by chlorine, bromine, and the nitric
elements. When heated with potash it evolves volatile
bases, among which are ammonia and me tb amine.
Nareotine is another alkaloid, which occurs in consider-
able quantity in opium, and is separated from the morphine
by being very soluble in ether and insoluble in water. It
forms brilliant transparent crystals, and has the formula
C^HjjNO^. Nareotine is but a feeble base : by oxydizing
agents it is decomposed, and yields a peculiar acid called
the opianic C^H^O^, and a new alkaloid, cotarnine
C^HjgNOg. In addition to these there have been observed
several other bases in smaller quantities in opium : such
are narceine, papaverine, and thebaine ; they are but little
known. Opium contains also a peculiar tribasio acid, the
meconic C14H4014. It is not improbable that in certain
seasons and conditions of soil and climate, different alkaloids
may be formed in the same plant, and to an extent replace
each other ; that such is the case with different species of
a genus is shown by the history of cinchona and some other
plants.
Digitized
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VEGETAL ALKALOIDS. 475
821 . Strychnine. — This alkaloid is found in the Sirychnos
nux-vomica, and several other plants of the same genus. It
is prepared by digesting the nux-vomica with water acidu-
lated by sulphuric acid, and precipitating the solution by
caustic lime. The impure precipitate is boiled with alcohol
and animal charcoal, and the liquid on cooling deposits the
strychnine in crystals. It is almost insoluble in water, abso-
lute alcohol, and ether, but dissolves in dilute alcohol : its
salts are crystallizable, intensely bitter, and highly poisonous.
Strychnine and its compounds produce a spasmodic affection
of .the muscles of voluntary motion; they are used in minute
doses in cases of paralysis. The poison of the celebrated
upas is the product of the Strychnos tieute, and owes its
activity to strychnine. The formula for strychnine is
C49HMNfl04.
Brucine is another organic base, which is associated with
the last, in several species of Strychnos. It resembles strych-
nine but is more soluble in water and alcohol, and although
similar in its action upon the animal system, is less potent.
Its formula is C^H^NgOg. Both of these bases yield pro-
ducts in which the hydrogen is in part replaced by chlorine
and bromine.
822. Piperineis a crystalline alkaloid extracted from black
pepper, and is a feeble base : the formula C70Hs6Nfl010 is
assigned to it. When heated with a mixture of hydrate of
potash and quick-lime it disengages two volatile bases, one
of which appears to be picoline, an alkaloid which is meta-
meric with aniline, and is obtained as a product of the dis-
tillation of bones. The other, to which the name of piperi-
dine is given, has the formula C^H^N : it boils at 212° F.,
is soluble in water, caustic, and has a strong odor of am-
monia. Piperidine is homologous with arsine and stibethine,
having the general formula CnHM.1N; N being replaceable
by As or Sb. These are alcoholic ammonias which have
lost Ha, and may have one, two, or three atoms of the hydro-
gen in NH8 replaced by the alcoholic elements. Thus arsine
has but one, and stibethine three equivalents of the carbo-
hydrogen, while the new base has two, which may corre-
spond to the vinic and propionic, C4 and C8; or to the
butyric and methylic, C8 and Ca. Piperdine, with one
equivalent of hydriodic ether, exchanges H for C4HP to
form a new base ; but with a second yields an iodid, which
Digitized
byGoogk
476 ORGANIC CHEMISTRY
i8NC10H10Et2.I)and corresponds to the iodid of yinio am-
monium.
823. Theine; Caffeine, C16H10N404.— -This organic base ia
found in coffee, tea, the fruit of the Paulinia sorbalis, and
the Ilex paraguayensis, which affords the matte, or Paraguay
tea. It is most abundant in green tea, which contains from
two to five per cent. ; the best coffee does not yield one per
cent. To obtain it, a strong decoction of tea is mixed with
a solution of the surbasic acetate of lead, as long as a pre-
cipitate is formed ; to the clear solution a little ammonia is
added to precipitate the excess of lead, and the liquid by
evaporation furnishes theine in delicate silky crystals. It
is readily soluble in hot water and alcohol, and may be
volatilized without decomposition ; its taste is slightly bitter.
Theine is a feeble base, and its salts* are easily decomposed,
the chlorohydrate crystallizes beautifully. With nitrate of
silver it yields a salt in fine crystalline groups, which is
CaH10N404+NAg06.
It is worthy of notice, that the plants which furnish this
alkaloid are used by different nations to prepare a grateful
and gently stimulating beverage. As these substances
resemble each other only in containing theine, it is probable
that they owe their common properties to the presence of
this principle, and that, in some unknown manner, it pro-
motes digestion and the other vital functions. The Bra-
zilians prepare from the fruit of the Paulinia sorbalis an
extract called by them guarana, which is much esteemed
as a remedy in dysentery and nephritic complaints ; it con-
tains a considerable quantity of theine.
824. The seeds of the Theobroma cacao, from which cho-
colate is prepared, yield an alkaloid theobromine, which re-
sembles caffeine and is homologous with it : it is C^HgN^O^
and the common formula of the two is therefore CnHw_4.
N404. With chlorine and oxydizing agents these alkaloids
yield a series of interesting bodies, to which we shall again
advert.
825. Solanine,from the Solanum nigrum ,and several other
species, — hyoscy amine, from Hyoscyamus niger, — atropine,
from Atropa belladonna, and daturine, from I)atwa stramo-
nium, are alkaline principles which possess in great perfection
the poisonous properties of the plants from which they are
derived. They are obtained by somewhat complicated pro-
cesses, and are crystalline and volatile. Their salts are
Digitized
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VEGETAL ALKALOIDS. 477
employed in medicine. Veratrine is found in the Veratrum
album, or white hellebore; it forms a white crystalline
powder, which is insoluble in water, but soluble in alcohol.
It is a powerful acrid poison, but is used medicinally in
neuralgia with beneficial results. Aconitine is obtained
from the Aconitum napellus, and resembles veratrine in its
Eroperties. Sanguinarine is an alkaloid which exists in the
lood-root, Sanguinaria canadensis, and to which this plant
owes its active properties. Emetine, the emetic principle
of ipecacuanha, is also an organic alkaloid. There are many
other oxygenized bases which have been artificially formed.
Such are benzoline, which has been described as an isomeric
modification of hydrobenzamid, and many more, which the
limits of this treatise will not permit us to notice.
826. Of the volatile bases analogous to aniline and chino-
line, obtained from plants, but two have been much studied,
nicotine and conine. Nicotine is the alkaloid of tobacco,
and is obtained by distilling a concentrated infusion of the
plant with lime or hydrate of potash. The recent plant
contains a peculiar crystalline body, called nicoiianine, which
affords nicotine by the action of caustic potash ; but in the
prepared tobacco, nicotine exists ready formed, and can be
extracted by the action of ether to which a little ammonia
has been added. When tobacco is smoked in a German
pipe, the liquid which condenses in the well contains a large
quantity of this alkaloid. The strongest Virginia tobacco
affords, when dry, six or seven per cent, of the alkaloid, and
mild Havanna tobacco no more than two per cent.
The formula of nicotine is C^H^N^. It is an oily liquid
heavier than water, in which it is somewhat soluble. It
distils at a high temperature unchanged. The taste of
nicotine is very acrid, and its odor recalls that of tobacco ;
it is extremely poisonous. This base is strongly alkaline
and forms very soluble salts ; it fixes 2HC1 to form a deli-
quescent chlorohydrate.
827. Conine is obtained from the hemlock, Conium macu-
latum, by distilling any part of the plant with a dilute
solution of hydrate of potash. Like the last, it is an oily
liquid, which is slightly soluble in water, and possesses iu
a high degree the smell, taste, and poisonous properties of
the hemlock. It is strongly alkaline, and yields a series of
deliquescent salts ; the formula of conine is O^H^N.
There still remain to be described a number of other
Digitized
byGoogk
478 ORGANIC CHEMISTRY.
vegetable substances which are Dot included under any of
the previous classes. Among them are some neutral bodies,
like amygdaline, salicine, and populine, which are inte-
resting from the peculiar metamorphoses of which they are
susceptible ; and besides these, several substances used in
coloring, among the most important of which, in regard to
its chemical history, is indigo.
828. Amygdaline. — This substance exists in the propor-
tion of four or five per cent, in bitter almonds ; it is also
met with in the kernels of peaches and cherries, and in the
leaves and young shoots of many species of Sorbus, JPrunus,
and others of the Pomacece. It is obtained from bitter
almonds from which the fat oil has been removed by pressure
between heated plates, by boiling the residue in strong
alcohol. The alcohol is then distilled off in a water-bath,
and the syrupy residue, mixed with a little yeast, is set aside
to ferment : by this treatment a portion of sugar which the
almonds contain is destroyed. The clear liquid is again
evaporated to a syrup and mixed with ether, which precipi-
tates the amygdaline in a crystalline powder. It is readily
soluble in alcohol and water, and crystallizes from the latter
in large prisms, with three equivalents of water ; it has a
bitter taste. The formula of amygdaline is C^H^NO^:
when boiled with solution of baryta, it takes up the elements
of one equivalent of water, and is converted into ammonia
and amygdalic acid, which remains dissolved as amygdalate
of baryta. Amygdaline may be regarded as the amid of
this peculiar acid, which is C^H^Q^.
Bitter almonds contain, besides amygdaline and a fat oil,
a large portion of a nitrogenous substance, to which the
name of emuUine is given ; it constitutes the principal part
of sweet almonds, which contain no amygdaline. When
bitter almonds are bruised with water, or when an aqueous
solution of amygdaline is mixed with a small portion of
emulsine from sweet almonds, a peculiar decomposition
ensues. The solution acquires the odor of the essence of
bitter almonds, and the amygdaline is found to be converted
into prussic acid, benzoilol, and grape sugar. Amygdaline,
with two equivalents of water, contains the elements of these
three compounds; 040H?7NO3a+2HaOfl=C9NH+C14H6Oi,
-•(-C^H^O^. Amygdalic acid, when distilled with sulphuric
acid and peroxyd of manganese, yields also bitter-almond
essence, with carbonic and formic acids. The action of
Digitized
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SALICINB. 479
emulsine in producing this cnrious change may be compared
to that of diastase, to which emulsine has a certain resem-
blance. If its solution is heated to 212° F., it is precipi-
tated in an insoluble form, and has no longer any action on
amygdaline.
829. Salieine. — This principle exists in the bark of those
species of willow which have a bitter taste. The decoction
of the bark is mixed with the surbasic acetate of lead as long
as a precipitate is formed ; to the filtered liquid dilute sul-
phuric acid is added to precipitate the dissolved lead, care-
fully avoiding an excess. The solution is then decolorized
by animal charcoal, and, by evaporation and cooling, deposits
pure salieine. It is so abundant in the bark of some willows
as to separate in crystals when a concentrated decoction is
cooled. Salieine forms small white crystals, readily soluble
in alcohol and water ; it has a very bitter taste, and is em-
ployed in medicine as a febrifuge and tonic. Its formula is
When a solution of salieine is mixed with a small portion
of the emulsine of sweet almonds, and heated for some hours
to 105° F., it is completely decomposed into grape sugar,
and a new compound which separates in fine rhombohedral
crystals, and is named saligenine. It contains C14IL04, and
its formation from salieine is thus represented : CajHggOgg-r-
2H309= 0^^0^+20,^30,. Saligenine is readily soluble
in water, alcohol, and ether ; by the action of dilute acids
it loses HaOa, and is changed into a white substance insoluble
in water, called saliretine. When a solution of salieine is
heated with dilute chlorohydric or sulphuric acid, it is at
first decomposed into grape sugar and saligenine, but the
further action of the acid converts the latter into saliretine,
which separates in white flakes. When a solution of salige-
nine is mixed with chromic acid or oxyd of silver, these are
reduced, and the oxygen combining with the saligenine
forms salicylol and water; C14H804+AgflOa==014H604+
HaOa-|-Ag9. Salieine, when distilled with a solution of
bichromate of potash and dilute sulphuric acid, yields a
large amount of salicylol; identical with the essence of
spirea ulmaria.
830. Dilute nitric acid by heat decomposes salieine with
oxydation into grape sugar and salicylol, which, by oxyda-
tion, yields salicylic and nitrosalicylic acids ; the final pro-
duct, with a concentrated acid, is nitropicric acid. If sali«
Digitized
byGoogk
480 ORGANIC CHEMISTRY.
eine is dissolved in dilate cold nitric acid, a new compound
is obtained, which is formed from salicine by the fixation of
oxygen and the separation of water; CMH8602S+04 =
CjgH^Ogo+I^Og. This substance, which separates from the
solution in crystals, is called helicine, and, by the action of
emulsine or dilute acids, is decomposed into grape sugar and
•alicylol, CMHM080+H,0,=C„H34084+2CMHe04.
831. Populine. — This is a crystalline substance which is
obtained from the leaves and bark of the aspen-tree, Popultu
trenwla. It resembles salicine, but is less soluble, and has
a sweetish taste. With acids it yields benzoic acid, grape
sugar and saligenine, and when boiled with a solution of
baryta, is completely decomposed into salicine, and benzoic
acid, which combines with the baryta. Populine is repre-
sented by CboH^Ojj, and by fixing H80a is converted into
salicine and benzoic acid, C80H¥08a+2H908=C52Hsfl098+
2C14H604. To indicate this relation, the name of benzosalicine
has been proposed for the principle. When dissolved in
cold nitric acid, a new substance is obtained, which is termed
benzohelicine, and by boiling with magnesia is decomposed
into a benzoate and helicine. Neither of these compounds
is affected by emulsine, but the action of acids and alkalies
converts benzobelicine into grape sugar, and the metameric
bodies, benzoic acid and salicylol.
832. Phloridzine. — This substance is contained in the root-
bark of the apple, pear, cherry, and some other trees. When
a concentrated decoction of the bark is cooled, it is deposited
in a crystalline powder, which, when purified, forms delicate
silky crystals, sparingly soluble in cold water, but readily in
alcohol. It has a slightly bitter taste, and is supposed to
possess febrifuge properties. The probable formula of phlo-
ridzine is C^HggO^, but it crystallizes with 2HaOa. When
boiled with dilute acids, it is decomposed like salicine into
glucose and a crystalline insoluble substance called pMore-
tine C^H^Og. When exposed to the action of moist air
and ammoniacal vapors, phloridzine is converted into a
dark-blue mass, very soluble in water, from which acetic
acid precipitates a red powder that dissolves in ammonia
with a magnificent blue color. It is called pkhrizeine,
C«Has024+08+2NH8 = C48H89Nfl080+HaOa. The ammo-
niacal solution of phlorizeine is rendered colorless by proto-
salts of tin, sulphuretted hydrogen, and other deoxydizing
agents, but on exposure to the air reossumes its color by
Digitized
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COLORING MATTERS. 481
the absorption of oxygen. This substance acts tbe part of
a feeble monobasic acid, and gives splendid colored precipi-
tates with metallic salts. If a salt of alumina or hydrated
alumina is added to the ammoniacal solution, it combines
with all the coloring matter and forms a blue precipitate,
leaving the solution colorless.
The action of phlorizeine with alumina is analogous to that
of many dye-stuffs, which form with oxyd of tin or alumina
insoluble colored compounds. This property of alumina has
already been alluded to ; when a tissue of cotton is first im-
pregnated with a solution of the acetate of this base, then
dried and immersed in a hot solution of a coloring matter
like phlorizeine, this is precipitated, and the insoluble co-
lored compound is fixed in the tissue.
833. There are several other principles obtained from
plants or animals, which are characterized by this property
of forming insoluble colored compounds with metallic oxyds,
like oxyd of tin or alumina, and are hence employed in the
art of dyeing as coloring matters. We shall briefly notice
the more important of those which have already been in-
vestigated. In some instances, the plants contain principles
which generate the coloring matters by decompositions, such
as we have seen in the case of phloridzine. Such is the
origin of the colors of the lichens and of madder.
o34. Several species of lichen, as the RocceUa tinctoria of
South America and the Cape of Good Hope, the Lecanora
tartarea of Northern Europe, and some others, are used for
the fabrication of a blue or purple dye-stuff, known by the
different names of archil, litmus, cudbear, and tournsol.
When these lichens are digested in the cold with milk of
lime, the solution yields with acids a white precipitate,
which may be crystallized from alcohol and from its solu-
tion in boiling water. It is an acid, and forms crystal-
lizable salts. The names of lecanorine, lecanoric acid, and
orsellic acid have been applied to it by different investigators;
fcs composition is represented by 083H14014. When a solu-
tion of lecanoric acid is heated to ebullition with an excess
of lime or baryta, a new acid is formed by the fixation of
the elements of water; CMH14014+H„0fl = 2C18H808, which
is the formula of the new acid, to which the name of orsel-
linic or lecanorinic has been given. It is crystalline and
more soluble than the lecanoric acid ; when its alcoholic solu-
tion is treated with chlorohydric acid, or even when simply
81
Digitized
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482 ORGANIC CHEMISTRY.
boiled, the crystallizable ether of the acid, C^H^CJftJOg is
obtained, which has also been described under the names of
pseuderythrine and leccmoric ether.
When this ether is boiled for some time with baryta water,
it is decomposed with the evolution of alcohol, into carbonic
acid and a new substance, orcine ; the same body is obtained
by a similar process from the two acids, and by the dry dis-
tillation of lecanorine. The lecanorinic acid breaks up into
carbonic acid and orcine ; C^HgOg^CaO^+C^HgO^ which
is the formula of orcine. It forms large colorless prismatic
crystals of a sweet taste, which are very soluble in water,
and volatile without decomposition. When orcine is moist-
ened with ammonia and exposed to the air, it absorbs oxygen,
and is converted into a splendid purple coloring substance,
which resembles the analogous product from phloridzine,
and is named orceine. Its probable formula is (L4HgN06 :
orsellic and orsellinic acids also yield orceine when their
ammoniacal solutions are exposed to the air.
835. The lichen, called Evernia prunastri, yields evemic
acidy which appears to be homologous with lecanoric acid,
and to be C34H16014 : when boiled with an alkali it is de-
composed into orcine, and a new acid homologous with
lecanorinic, which is called everninic acid ClgH10Os. The
Gyroplwra pustulate, known in Canada as tripe de rochc,
and many other species, contain analogous substances, all
of which are available for the manufacture of archil. For
this purpose the lichens are ground to a paste with water,
a solution of ammonia and sometimes urine is added, and
the whole frequently stirred, until, by the action of the air,
the whole of the orsellic acid is converted into orceine, when
the mixture assumes a magnificent purple color. Further
exposure to the air turns it blue, and forms what is known
in commerce as litmus. When the proper colors have been
developed, lime and plaster of Paris are added to the mass,
to give it bulk and consistency, and the whole is dried.
Archil is used with solution of tin, especially in the dyeing
of silks. Litmus colors the common test-paper for acids,
which, decomposing the blue compound with lime or am-
monia, set free the red orceine. Many salts which are
capable of decomposing this feeble combination, restore the
red color of litmus, and are thus said to possess an acid
reaction.
836. The roots of madder, Rulia tinctoria, contain in theii
Digitized
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COLORING MATTEBS. 48?
recent state, according to the latest investigations, a yellow
crystalline substance, called xanthine or ruberythric acidm
which, when boiled with acids or alkalies, is decomposed into
glucose and an orange-red volatile crystalline substance,
sparingly soluble in water, to which the name of alizarine it
given. The formula CaoH^Oj,, has been assigned to it. Se-
veral other compounds have been described as obtained from
madder, but alizarine appears to be the true coloring prin-
ciple. Madder is used in giving to cotton the much valued
Turkey-red dye, which is produced by the conjoined action
of a salt of tin, alumina, and alizarine : the combination of
the coloring principle with alumina forms the red pigment
called madder lake.
837. The red coloring matters of alkanet or anchusa, of
sandal-wood, and of carthamus are insoluble in water, but
soluble in alkalies, and appear to possess acid properties.
The latter, carthamine, is the coloring principle of the pink
saucers used in dyeing flowers and feathers. On the addi-
tion of acetic acid to its alkaline solution, it is precipitated
xu an insoluble form, and then fixes itself on the tissue
without the intermedium of a metallic oxyd. Hematoxy*
line is obtained from logwood ; it is very soluble and forms
yellow crystals : its solutions are rendered blue by alkalies
and red by acids, and give a violet color with alum, and a
black with salts of iron.
The coloring principle of the cochineal insect is a purple
body, very soluble in water and alcohol ; it forms beautiful
lakes and scarlet dyes with salts of tin and alumina, and has
been called carminic acid; the formula C^H^O^ is assigned
to it. The pigment known as carmine is a lake obtained
from cochineal with alumina.
838. The yellow coloring matters of plants are generally
non-azotized substances. Among the most important are quer-
citrine, the coloring principle of the Quercus tinctoria, and
luteoline} from the wood, Reseda luieola, both of which are
soluble and crystalline. The yellows of turmeric and gam-
hoge are of a resinous nature. Others employed in dyeing
are morine} from the Morns tinctoria, and annatto.
The leaves of plants contain a green resinous matter,
which is soluble in alcohol and ether, and seems to possess
acid properties ; it is called chlorophyll. The blue and red
colors of flowers are very perishable, and have not been accu-
rately examined. Those of the violet, iris, dahlia, and many
Digitized
byGoogk
484 OfeGANIO CHEMISTRY.
other flowers, are turned red by acids and green by alkalies.
A most delicate test-paper is prepared with an alcoholic in-
fusion of the petals of purple dahlias.
839. Indigo. — This important coloring substance is ob-
tained from a great number of plants, the principal of which
are the Indigo/era tinctoria and I. anil, with some species
of the genera Isatis, Nerium, and Polygonum. The juices
of these contain a peculiar colorless principle in solution,
which, when exposed to the air, absorbs oxygen, and is con-
verted into indigo. In the manufacture of this substance,
the plants are steeped in water, and made to undergo a kind
of fermentation ; the clear liquid is then exposed to the air,
and frequently agitated to facilitate the absorption of oxy-
gen ; by this process it gradually becomes blue, and deposits
the insoluble indigo.
840. Indigo is obtained in strongly cohering masses of a
deep blue, which assume, when rubbed, a coppery metallic
lustre. That of commerce is never pure, but is mixed with
various foreign matters. Indigo is insoluble in water, alco-
hol, oils, dilute alkalies, and chlorobydric acid : when cau-
tiously heated it is volatilized as a purple vapor, which
condenses in delicate crystals. The composition of indigo
is expressed by ClflH5N09.
In contact with water and de-oxydizing agents, indigo is
converted into a colorless substance, which is soluble in
alkaline liquids ; this is generally effected by a mixture of
lime and sulphate of iron : one part of indigo in fine powder,
four parts of quicklime, and three of protosulphate of iron
are digested with a large quantity of water. The protoxyd
of iron formed by the action of the lime, reduces the indigo,
which in this form is dissolved by the alkaline solution,
forming a yellow liquid. If this is exposed to the air, oxy-
gen is absorbed, and the indigo is separated in its original
color and insolubility. It is by impregnating cloth with
this solution, and precipitating the indigo in its texture by
the action of the air, that the fine indigo-blue colors are
produced.
841. Chlorohydric acid added to this yellow solution,
precipitates the dissolved substance as a gray crystalline
powder, which, when moist, rapidly becomes blue by absorb-
ing oxygen, and is converted into indigo.
It is called indigogen, and has the formula CjjH^N^CL :
exposed to the air it fixes Os, and is converted into HaOf
Digitized
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COLORING MATTERS. 485
and 2ClflH,NOfl. When indigo is boiled with an alcoholic
solution of caustic soda and grape sugar, it is converted into
indigogen, while formic acid is produced by the oxydation
of the sugar. This alcoholic solution, exposed to the air,
deposits pure indigo in crystals.
842. Concentrated sulphuric acid dissolves indigo by the
aid of a gentle heat, and forms two acids, (652,) which are
produced by the union of one and two equivalents of indigo
with one of sulphuric acid, the elements of water being
eliminated. They are named the sulphindigotic and sulpho-
purjmric acids, and, like their salts, are intensely blue. The
first named is the most important : when a solution of sulph-
indigotic acid is boiled with woollen cloth, it is completely
decolorized, the acid being taken up by the cloth ; in this
way the color called Saxon blue is obtained. It resists
completely the action of water, but is easily dissolved out by
a solution of the carbonate of ammonia, which distinguishes
it from the blue color obtained with solutions of indigogen.
843. If powdered indigo is heated with a solution of
chromic acid or dilute nitric acid, it dissolves and forms a
yellow solution ; this, on cooling, deposits beautiful orange-
red prisms of a new substance, called watine, which is formed
from indigo by the combination of Oa, and is C16H5N04 :
with potash it forms a salt of natinic acid, which, when sepa-
rated from the alkaline base, is decomposed by a gentle heat
into isatine and water. Isatine forms several amids with
ammonia. When it or indigo is distilled with caustic potash,
a large quantity of aniline is obtained : the intermediate
product is formed when indigo is dissolved in a solution of
potash; a yellow solution is obtained, which appears to
contain reduced indigo, and a salt of isatinic acid, but on
evaporating to dryness and fusing the mass, hydrogen is
evolved, and carbonic and anthmnilic acids are formed. An-
thranilic acid contains C14H7N04. It is soluble, crystalliza-
ble, and volatile, but, when mixed with sand and rapidly
distilled, is completely decomposed into carbonic acid gas
and aniline: C14H7N04 = 0,0^+0 JHyN.
The action of chlorine upon indigo destroys its blue color,
and transforms it into a species of isatine in which one and
two equivalents of hydrogen are replaced by chlorine.
These resemble normal isatine, and, when distilled with
potash, yield species of aniline in which the same substitu-
tion exists. Dilute nitric acid converts indigo by long boil-
Digitized
byGoogk
486 ORGANrC CHEMISTRY.
ing into ammonia, carbonic, and nitrosalicylic acids ; with
stronger nitric acid it forms nitropicric aoid.
THE CYANIC COMPOUNDS.
844. The bodies of tbis series are obtained as products
of a great number of reactions, and are very important in
tbeir relations to organic chemistry. A cyanid was first
recognised in a product of the action of potash upon dried
blood, which was employed for producing, with a salt of iron,
a fine blue pigment, known as Prussian or Berlin blue :
hence the name, from the Greek, kuanos, blue.
The ammoniacal salts of the acids CnHn04 yield, as we have
shown, nitryls by the loss of 2H2Oa, which regenerate the
ammoniacal salt by again assimilating the elements of water.
The general formula of these bodies is C^H^^N. The
nitryl of formic acid *• ^HN, and is formed when the vapor
of formate of ammonia is passed through a red-hot tube ;
Ca(H.NHJ04=CflH5N0 — 2H2Ofl = CflHN. This nitryl is
the parent of the cyanic series, and is commonly known as
prussic or hydrocyanic acid. The equivalent of hydrogen
which it contains may be replaced by a metal, and the salts
called cyanid* thus obtained. The cyanid of potassium is
formed when nitrogen gas is passed over a mixture of char-
coal and carbonate of potash, heated to the temperature at
which potassium is evolved. It is sometimes found as a pro-
duct in furnaces from the action of atmospheric nitrogen
upon the intensely heated mixture of carbon and alkali
resulting from combustion : the potassium in this case unites
directly with carbon and nitrogen. Cyanid of potassium is also
obtained when animal substances, like leather, horn, or dried
blood, or the charcoal obtained from them, which contains
several per cent, of nitrogen, are heated with carbonate of
potash ; its separation and purification will be described
farther on.
845. Hydrocyanic acid, is easily obtained by distilling
cyanid of potassium with dilute sulphuric acid, or by decom-
posing cyanid of mercury at a gentle heat by sulphuretted
Lydrogen 5 20aHgN+H3S8=2CaHN+HgaSa.
To procure the anhydrous acid, the best arrangement is
shown in fig. 420. Cyanid of mercury in coarse powder is
placed in the tube a o, and decomposed by a gentle cur-
tent of Bulphydric acid, evolved from sulphid of iron and
Digitized
byGoogk
CYANIC COMPOUNDS.
487
Fig. 420.
diluted sulphuric acidi The sulphydric acid is dried by
passing it over chlorid of calcium in the tube c d, and the
product of the action is collected in the bent tube contained in
the freezing mixture C. The operation may be conducted with-
out danger in the open air. Pure hydrocyanic acid is a color-
less limpid liquid, which boils at 80° F., and has a specific
gravity of -697 ; a drop of it let fall upon paper, produces so
much cold by its partial evaporation, as to freeze the remain-
der. Hydrocyanic acid is combustible, and burns with a
white flame; it is scarcely acid in its reaction with test-papers :
its taste is pungent and aromatic, and its odor very powerful,
both recall those of peach blossoms or bitter almonds ; the
distilled waters of these substances and of the cherry-laurel,
owe a part of their flavor to the presence of the acid, which
is one of the products of the decomposition of amygdaline
by eraulsine. When hydrocyanic acid is mixed with an
excess of strong chlorohydric acid, it is completely decom-
posed into sal-ammoniac and formic acid ; boiled with hydrate
of potash, it is decomposed in a similar manner, and yields
ammonia and formate of potash : CflHN-f-HaOa-f-(KH)Oa==
CaHK(X+NH8.
846. Hydrocyanic acid is a most fatal poison; a single
drop of the concentrated acid placed upon the tongue of a
large dog produces immediate death, and the diluted acid
even in very small doses causes giddiness and nausea. It
appears to act as a sedative to the arterial system, and the
suspension of animation following a large dose of it, does not
always result in death, if proper remedies are employed.
Ammonia and brandy are considered the most efficient anti-
dotes to its effects. The vapor of the acid is also poisonous
when inhaled; but workmen constantly exposed to it in a
diluted state appear to become accustomed to it, bo as to
Digitized
byGoogk
488 ORGANIC CHEMISTRY.
experience no deleterious effects. The dilute acid is em-
ployed in medicine ; when pure, it readily undergoes sponta-
neous decomposition, yielding ammonia and a brown inso-
luble matter; but if it is diluted, and a trace of sulphurii
acid is present, the acid may be preserved for a long time,
especially if secluded from the light
The cyanid of potassium CfKN is deliquescent and very
soluble in water and alcohol ; it forms cubic crystals, and
has the taste, smell, and medicinal properties of hydrocyanic
acid : it is strongly alkaline in its reactions. Cyanid of
ammonium CLAmN = Cf H4Nf is obtained by saturating hy-
drocyanic acid with ammonia, and is volatile and very poison-
ous. Hydrocyanic acid dissolves red oxyd of mercury, and
the solution yields colorless crystals of a cyanid CaHgN,
which are soluble in water and alcohol, and are poisonous.
Hydrocyanic acid and soluble cyanids throw down from
solutions of silver a white curdy precipitate insoluble in
acids, and resembling the chlorid ; it is cyanid of silver, and
is insoluble in ammonia. Salts of palladium decompose even
the cyanid of mercury, and form an insoluble precipitate of
cyanid of palladium. The other cyanids are obtained by
double decomposition : they are generally insoluble in water,
but soluble in cyanid of potassium, forming salts, which
will presently be described.
The action of chlorine upon hydrocyanic acid or cyanid
of mercury, yields a compound in which chlorine replaces
the hydrogen of the acid ; it is a gas of a very strong odor,
and at a low temperature crystallizes in colorless needles :
it dissolves in water without decomposition, for the solution
does not precipitate salts of silver. Its formula is C8C1N :
the bromic and iodic species are crystalline and very volatile.
These compounds are commonly called chlorid and iodid
of cyanogen ; the name of cyanogen being applied to the
group CgN, which plays the same part in the saline combina-
tions as CI does in the chlorids, and is often represented by
the symbol Cy, the hydrocyanic acid being CyH.
847. When the carefully dried cyanid of mercury is
heated nearly to redness, it is decomposed into metallic mer-
cury, and a colorless gas which is liquefied by a pressure of four
atmospheres. It has a pungent odor, resembling that of prussio
acid, and burns with a beautiful violet purple, yielding nitrogen
and carbonic acid gas; it is soluble in water and alcohol, and
must therefore be collected over mercury. This gas is called
Digitized
byGoogk
CYANIC COMPOUNDS. 489
tyanogcn : the formula of its equivalent of four volumes is
C4N9. It is therefore not the hypothetical compound repre-
sented by Cy, but sustains the same relation to it that the
equivalent of four volumes of chlorine, Clfi does to the atom
CI which enters into the composition of a cblorid. In its
formation, two equivalents of cyanid of mercury react upon
each other, CyHg+CyHg=Hg2+Cya = C4Na. When heat-
ed with potassium, combination ensues with combustion, and
oyanid of potassium is formed.
Cyanogen corresponds to the nitryl of oxalic acid ; oxalate
of ammonia, C4Ha08.2NH8=C4H8Nfl08--4H90a=C4Nr
Its aqueous solution decomposes by keeping, and a variety of
products are obtained, among which is oxalate of ammonia,
regenerated by a combination of cyanogen with the elements
of water. When one volume of cyanogen and two of sulphu-
retted hydrogen gas are mixed in the presence of water
or alcohol, direct combination ensues, and the compound
C4N8.H4S4 is obtained, which corresponds to sulphuretted
oxamid: it forms orange-red crystals, soluble in alcohol,
but sparingly soluble in water. When boiled with a dilute
solution of potash, it evolves ammonia, and is completely
converted into oxalate and hydrosulphate of potash,
C4H4N9S4+4(KH)0fl=2NH8+C4Kll08+2(KH)S8. By
boiling with chlorohydric acid, the crystals are converted
into oxalic acid, ammonia, and sulphuretted hydrogen.
848. Cyanates* — The cyanids combine with oxygen to
form a new class of salts, called cyanates. Fused cyanid
of potassium absorbs oxygen from the air, and reduces
oxyd of copper and other metals with ignition, at a tem-
perature below redness. By adding oxyd of lead, in small
quantities, so long as reduction takes place, the cyanid is
completely converted into cyanate, and the lead separates in
a metallic state. The fused mass may be crystallized by solu-
tion in boiling alcohol, and is deposited in pearly plates, very
soluble in water; CaKN+Pb3Oa = CaKNOa+Pba. Strong
acids liberate the cyanic acid, but decompose it immediately
into carbonic acid and ammonia. Cyanic acid may be con-
sidered as the acid nitryl of carbonic acid, derived from bi-
carbonate of ammonia by the loss of 2HaOa. C9Ha08.NH8=
2H8Oa+CaHNOfl. Its aqueous solution is readily decom-
posed, especially in the presence of strong acids and alkalies,
into a carbonate and ammonia, and the crystals of cyanate of
potash in a moist atmosphere attract water, and, evolving
Digitized
byGoogk
490 ORGANIC CHEMI8TRT.
ammonia, are converted into bicarbonate of potash. Cyanic
acid is obtained in a pure form by the distillation of cyan uric
acid : it is a colorless, volatile liquid, with an odor like acetic
acid, and is very caustic, blistering the skin. It may be pre-
served in a freezing mixture, but at the ordinary temperature
changes very rapidly into a white, solid, insoluble, isomerio
modification, called cyamelid, which by heat is reconverted
into cyanic acid.
849. Cyanic acid combines directly with two equivalents
of ammonia, and forms a soluble salt having the reactions
of a cyanate of ammonia; but if its solution is boiled, am-
monia is evolved, and a substance having the composition
of neutral cyanate of ammonia remains in solution ; it is an
alkaloid, and combines directly with acids. The same com-
pound is obtained as a product of the spontaneous decompo-
sition of an aqueous solution of cyanogen or cyanic acid ; the
ammonia formed from one portion of cyanic acid, uniting
with undecomposed acid, yields C9HN09.NH3 = C3H4N909.
This alkaloid exists in human urine, and has hence been
named urea. When fresh urine is evaporated by a gentle
heat to a small bulk, and mixed with an excess of nitric
acid, the nitrate of urea C2H4N909.NH06, which is spar-
ingly soluble in the dilute acid, separates in large brilliant
plates; these may be washed with iced water and decom-
posed with carbonate of potash : the urea is then separated
from the nitre by alcohol, in which the former alone is
soluble.
850. A better process for its formation is by cyanate of
potash : the salt known as the yellow prussiate of potash con-
tains the elements of cyanid of potassium and cyanid of iron.
It is dried at 212° F., and eight parts of it are mixed with
three of dry carbonate of potash, and the mixture fused at
a low red heat in an iron crucible : the iron separates in a
spongy metallic form, and a white crystalline mass is ob-
tained, which is cyanid of potassium, mixed with about one-
fourth of cyanate, and is known in the arts as Liebig's
cyanid of potassium. If to this mass, still in fusion, fifteen
parts of red-lead are gradually added, the whole is converted
into pure cyanate of potash. It is to be dissolved in cold
water, mixed with a solution of eight parts of sulphate of
ammonia, and evaporated to dryness. The cyanate of am-
monia, formed by double decomposition, is thus converted
into urea, which is separated from the accompanying sol*
Digitized
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CYANIO COMPOUNDS. 491
pbate by boiling tbe residue in alcobol. It crystallizes,
on cooling, in transparent, colorless prisms, readily soluble
in water and alcobol, and having a fresh, sharp taste, like
nitre. It is a weak base, but forms compounds with oxalic
and chlorohydric as well as with nitric acid ; concentrated
sulphuric acid and hydrate of potash, by the aid of heat,
convert it into carbonate and ammonia. When urea is
evaporated to dryness with a solution of nitrate of silver,
the elements arrange themselves so as to form nitrate of
ammonia and an insoluble crystalline cyanate of silver,
which explodes by heat. A solution of urea heated in a
sealed tube to 284° F. is converted into carbonate of am-
monia CflH4Ns04+2H3Oa=C3HflOfl.2NH3. The urea in
urine undergoes the same change by boiling or by putre-
faction. Nitrous acid at once decomposes it into water,
nitrogen, and carbonic acid gases, 2NH04+C2H4N909 ==
3Ha09+Cf04+N4.
851. Sulphocyanates. — Fused cyanid of potassium reduces
sulphurets in the same way as oxyds, and combines directly
with sulphur to form a cyanate CaKNS„ in which sulphur
replaces oxygen. If a mixture of dried prussiate of potash
is fused with sulphur and carbonate of potash in a covered
crucible, and the heat gradually raised to redness, until the
mass is in quiet fusion, there is obtained a mixture of sulpho-
eyanate of potash and sulphuret of iron. The salt is dis-
solved out by boiling water, and crystallizes on cooling.
The best proportions are 46 parts of the dried prussiate,
17 of dry carbonate of potash, and 32 of sulphur. Sulpho-
cyanate of potash forms colorless prismatic crystals, having
a taste like nitre ; they are deliquescent, and soluble both
in water and alcohol. The svlphocyanic acid C9HNS9 is
obtained in solution when the lead salt is decomposed by
dilute sulphuric acid, and is a colorless liquid acid, with an
odor like vinegar. These compounds are all more stable than
the oxycyanates. Sulphocyanate of ammonia C£(NH4)NS.
is obtained by a peculiar reaction ; a solution of cyanid of
ammonium separates the excess of sulphur from persulphuret
of ammonium, and if a mixture of the two salts in solution
is digested with finely divided sulphur, the sulphur is dis-
solved by the sulphuret and transferred to the cyanid, which
is wholly converted into sulphocyanate : by boiling the solu-
tion, the volatile sulphuret of ammonium may then be ex-
pelled, and the sulphocyanate obtained in crystals. Tho
Digitized
byGoogk
492 ORGANIC OHEMI8TRT.
soluble sulphocyanates are characterized by forming a deep
blood-red liquid with persalts of iron, which is due to the
formation of a persulphocyanate of that metal ; this reaction
affords a very delicate test both for salts of iron and sulpho-
cyanates.
852. When a solution of sulphocyanate of potash is heated
with nitric acid, or when chlorine is passed through its solu-
tion, a yellow substance separates, which contains the ele-
ments of cyanogen, sulphur, oxygen, and hydrogen, and has
been called cyanoxsulphtd ; its nature is not well understood.
Exposed to heat, it yields sulphur and sulphuret of carbon
among other products, and leaves a yellow residue named
mellon, which is probably C^B^N,,, and by a strong red heat
is decomposed into cyanogen, nitrogen, and hydrogen gases.
Mellon decomposes fused sulphocyanate of potassa, and yields
a salt called mclbnid of potassium C jHKgNg. When this
salt or mellon is boiled with a solution of hydrate of potash,
ammonia is evolved and a salt obtained, to which the name
of cyamellurate of potash is given; it i8C12HK,N8Og: the
corresponding acid is sparingly soluble in water.
Polycyanids.
853. The cyanids exhibit a great tendency to polymerism,
and form compounds in which two, three, and six molecules
of simple cyanid are condensed into one. The mellon series
is an instance of such a polymerism. When cyanogen is ob-
tained by the decomposition of cyanid of mercury, a portion
of a black carbon-like body is always formed, which is repre-
sented by C1SN6, and is named paracyanogen. It contains
the elements of three equivalents of cyanogen, and is entirely
converted into it when heated in a current of carbonic acid
gas; C19N?=3C4Na. Heated in hydrogen gas, it yields
hydrocyanic acid, ammonia, and carbon; ClaN6 + Hla =
8C9HN+3NHS+C6. The brown substance formed by the
spontaneous decomposition of an aqueous solution of cyano-
gen or of hydrocyanic acid, is similar in its nature.
854. When boracic acid or a borate is heated with a cya-
nid, a compound of boron and nitrogen is obtained : it is, how-
ever, best prepared by igniting calcined borax with twice its
weight of sal-ammoniac ; the mass washed with water and
dilute acids, leaves a white insoluble powder, which burns
at a high temperature with a green flame, and when heated
Digitized
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CYANIC COMPOUNDS. 498
with hydrate of potash or strong sulphuric acid, is decom-
posed into a borate and ammonia : the same decomposition
is produced when it is heated in aqueous vapor. It reduces
oxyds of lead, copper, or mercury, at a temperature below
redness, with the evolution of nitric oxyd gas. The pro-
portions of its elements are represented by B4Na, but,
from its fixed nature, it is probable that it has a higher
equivalent, corresponding perhaps to paracyanogen.
856. The action of chlorine upon an aqueous solution of
hydrocyanic acid, the latter being in excess, yields a volatile
liquid, which is C6HClaN8, and corresponds to a triple mole*
cule of cyanid in which two atoms of hydrogen are replaced.
By the further action of chlorine the third atom is removed,
and the perchloric tricyanid C6C18N8 is obtained : this is
also formed when dry chlorine acts upon paracyanogen, or
upon the cyanid of mercury, with the aid of sunlight, and,
unlike the monocyanid, is a crystalline solid, which is vola-
tile at above 300° F. When the bichloric tricyanid above
mentioned is digested with oxyd of mercury, cyanid of mer-
cury and water are formed, with a pungent volatile liquid,
boiling at 61° P., which is OJu\^v or & perchloric dieyanid,
containing the elements of two equivalents of the mono-
cyanid. It is not decomposed by water, but with hydrate
of potash yields ehlorid of potassium, and the products of
the decomposition of cyanic acid, ammonia, and a carbonate.
856. The solid tricyanid is decomposed by water into chlo-
rohydric acid, and cyanuric acid, which is polymeric of the
cyanic, and is C6H8N806. tfhe same acid is formed when a
solution of cyanate of potash is mixed with a small quantity
of acetic or nitric acid insufficient for its complete decompo-
sition ; cyanurate of potash is deposited. When the com-
pound of chlorohydric acid and urea is heated, sal-ammoniac
sublimes and cyanuric acid remains; 8CfH4NaOa.HCl==
3HCl.NH8-f-C6H8N806; and urea, when heated alone until
it ceases to evolve ammonia, is converted into a grayish
mass, which is an amid of cyanuric acid. This is dissolved in
concentrated sulphuric acid, the solution decolorized by a
little nitric acid, and mixed with its bulk of water; the
cyanuric acid separates, on cooling, in prismatic crystals,
feebly acid to the taste. It may be crystallized unchanged
from a boiling solution in nitric or chlorohydric acid, but
by long continued ebullition with them, is slowly decomposed
like cyanic acid, into carbonic acid and ammonia. Wheo
Digitized
byGoogk
4M ORGANIC CHEMISTRY.
exposed to a strong heat it is decomposed into cyanic acid,
which is thus obtained pure, C6H,Na06=3CaHNOr
857. Gjanuric acid is tri basic, and forms both neutral
and acid salts. The cyanuric ether of alcohol, obtained by
distilling a sulpbavinate with alkaline cyanurate of potash,
forms beautiful crystals sparingly soluble in water, which
are fusible, volatile, and have the formula Ca(C4H5)sNsOi.
When sulphocyanate of ammonia is decomposed by heat,
a residue is obtained consisting of mellon and an amid of
cyanuric acid, to which the name of melamine is given. It
is dissolved from the crude product by a dilute boiling solu-
tion of hydrate of potash, and separates, on cooling, in color-
less rhombic octahedrons. It is C6H6N6, and differs by
8HaO& from the neutral cyanurate of ammonia. Melamine
is a strong organic base, and forms crystalline salts. When
boiled with strong acids or alkalies, it is slowly decomposed
into ammonia and a cyanurate. The intermediate steps in
the decomposition are the amids, corresponding to cyanu-
rates with one and two equivalents of ammonia, and are
called ammdid and ammeline. The latter is GeH5N509 and
is a weak base. By heat melamine is decomposed into mel-
lon and ammonia; 2C6H8Ne=C1JHsN9+3NH3.
858. Fulminates. — The salts which from their explosive
character have received this name, correspond to the dicya-
nid 0401sNa already described, and contain the elements
of two atoms of cyanate. When nitrous vapour is passed
into a solution of nitrate of silver in alcohol, the fulmi-
nate of silver C4AgaNa04 is deposited. The same salt is
formed when a solution of silver in a large excess of nitric
acid, is added to alcohol ; the action is complex; besides the
fulminate, aldehyd, acetic and formic ethers are formed by
the oxydizing power of the acid, and by a polymerism of
the alcoholic molecule, an acid which is homologous with
lactic acid and is C8H8013. The action of nitric acid upon
alcohol yields aldehyd and nitrous ether, and the deoxyda-
tion of another portion of the acid giving rise to nitrous
acid, this may react with the ether and form fulminic acid
and water, NH04+C4H5N04=C4H9Njl04+2Ha0a. The sil-
ver salt is sparingly soluble in water, and forms delicate
white crystals, which explode with terrible violence by fric-
tion with any hard body, even under water. The products
of the decomposition are carbonic acid and nitrogen gases,
and a mixture of cyanid with metallic silver. The fulminate
Digitized
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CYANIC COMPOUNDS. 405
of mercury is less explosive than the silver salt, and is the
material used in the preparation of percussion caps. To pre-
pare it, one ounce of mercury is dissolved by a gentle heat
in eight and a-half ounces by measure of nitric acid, of spe-
cific gravity 1*4, and the solution is poured into ten mea-
sured ounces of alcohol, specific gravity '830 ; action soon
ensues, with the evolution of copious white fumes, and the
fulminate is deposited in white crystalline grains, which are
washed with cold water, and dried at a very gentle heat.
The salt is somewhat soluble in boiling water, and crys-
tallizes on cooling ; it explodes violently by a heat of 390°
F., by friction,' percussion, and by contact with strong acids.
Its formula is C4Hg9Na04. When fulminate of silver is
dissolved in nitric acid, one-half of the silver is removed
and an acid salt separates, which is C4HAgNa04 ; chlorid
of potassium precipitates only one-half the silver and
yields C4KAgNaH4. Metallic copper separates the whole,
and forms a copper salt. The double fulminate of copper
and ammonia is decomposed by sulphuretted hydrogen into
urea, sulphocyanic acid, water, and sulphuret of copper. It
may be said to separate into cyanate of ammonia, which
changes to urea, and cyanate of copper, which yields sulphuret
of copper and cyanic acid ; this, with an equivalent of H9Sf,
is converted into water and sulphocyanic acid.
859. The relations of the cyanids to the bodies of the
series of alcohols are full of interest. When a sulphovioate
is distilled with cyanid of potassium, hydrocyanic ether is
•obtained as a liquid sparingly soluble in water and boiling
at 176° F. It is C2(C4H5)N or C6HSN, and is homologous
with hydrocyanic acid. When heated with hydrate of pot-
ash, it is not decomposed like other ethers, but evolves
ammonia, and produces a salt of propionic acid C8H8Oi
homologous with formic acid. The hydrocyanic ether of
wood-spirit C4HSN yields in the same way acetic acid,
C4H3N+2H3Ofl=NH8+C4H404. These ethers are identical
with the nitryls obtained by distilling the ammoniacal salts
of these acids with anhydrous phosphoric acid ; the amy-
lie ether is the nitryl of caproic acid, CiaHia04. The vinic
cyanic ether, with potassium, evolves a gas which is C4H6,
and the residue yields to water cyanid of potassium. A sub-
stance remains which may be crystallized from boiling
water, and is an organic base to which the name of cyane-
thine has been given. Its formula is C^H^N, correspond-
Digitized
byGoogk
496 ORGANIC CHEMISTRY.
ing to three atoms of hydrocyanic ether, and it pertains to
the type of the tricyanids.
860. When the crystalline compound of aldehyd and
ammonia is dissolved in water with a mixture of hydrocyanic
and chlorohydric acids, and evaporated to dryness, sal-am-
moniac is obtained, and the chlorohydrate of a new base,
which is formed from the elements of aldehyd, hydrocya-
nic acid and water, C4H4Oa+CaHN+H1Os=e6H7N04.
The name of alanine is given to this new substance, which
is crystalline, soluble in water and dilute alcohol, and has a
sweet taste ; an atom of hydrogen in it may be replaced by
a metal, so that, like ammonia, it combines both with acids
and metallic salts. By the action of nitrous acid, alanine is
converted into lactic acid, nitrogen and water, 2C6H7N04-{-
2NH04= C19H19019+2H908+N4.
861. A cyanic ether is obtained by distilling a sulpho-
vinate with cyanateof potash; it is Cfl(Et)NOa=C6H5NOt,
and is a very volatile liquid, which combines with ammonia
and forms a body crystallising in beautiful prisms, and solu-
ble in water and alcohol. It is C8H8N309, and is vinie
urea j differing from ordinary urea by 2C9H9; when decom-
posed by hydrate of potash, it yields carbonic acid, and one
equivalent of ammonia, with one of ethamine, or vinie
ammonia, NEJa(C4H5). In the same way vinie cyanic ether,
which is homologous with cyanic acid, is decomposed, car-
bonic acid and ethamine being the only products. The cyanic
ethers of the other alcohols yield similar results.
862. When the vapor of cyanic acid from the distilla-
tion of cyanuric acid is passed into alcohol, crystals are
deposited which contain the elements of one equivalent of
alcohol and two of the acid, C4HeOfl+2C9HN09=C8H8N9Oa.
This compound is decomposed by distillation into aleohol and
cyanuric acid, but with a solution of baryta, alcohol is set free
and the baryta salt of a new acid is formed, which is called
allophanic acid, and contains the elements of two equiva-
lents of a cyanate with one of water, being C4H4Nt0f ; it
differs from fulminic acid by Ht09, and is monobasic. When
acids are added to its salts, or when a solution of its baryta
salt is boiled, it is decomposed into a carbonate and urea ;
allophanic acid contains the elements of urea and carbonic
acid, C4H4Na06=CaH4N903+Cs04-
The vapors of cyanic acid are absorbed by aldehyd
Digitized
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CYANIC COMPOUNDS. 497
and a sparingly soluble crystalline compound is formed,
to wbich the name of trigenic acid is given. The formula
C8H7N804, representing a monobasic acid, is assigned to it,
but its equivalent is probably more elevated.
863. When cyanogen gas is passed into an alcoholic
solution of aniline, sparingly soluble crystals of a new base
separate. It bas received the name of cyaniline, and is
formed by the combination of one equivalent of cyanogen
and two of aniline, C4Np+2C19H7N = OwHuN4. Its salts
readily separate into aniline, and products of the decompo-
sition of cyanogen. Aniline absorbs the gaseous chlorid of
cyanogen, and the ehlorohydrate of a new base is formed,
0JD]N+201MU^ sOlH.Oa.H^,. The new alkaloid is
called melcmiline\ it is crystalline, and its salts are more
stable than those of cyaniline. It combines directly with
cyanogen to form a base analogous to cyaniline, to which the
name of cyamelaniline is given; it is C80H18NS. These
bodies are derived from a compound of two equivalents of
aniline, CMH14Ng ; melaniline is formed from it by the sub-
stitution of CyST for H : and the fixing of C4Na = (G^i\ or
Cya, is analogous to the direct combination of Cl9 and C1H.
A reaction similar to the last, in which CaHN or CyH com-
bines directly, is found in the vegetal alkaloid harmaline
CggH^NjPa ; when this base is mixed with hydrocyanic acid
or its salts with a cyanid, it combines with C9HN to form
a new crystalline base, a/anharmaline, CasC14H30fl+CaHN
=(u90H.15^309. This combination is decomposed by heat
into prussic acid and harmaline, but forms with acids, salts
which are permanent. Many other alkaloids, besides ani-
line, form compounds with cyanogen and cyanids.
864. By the action of chlorine gas in sunlight upon a
hot saturated solution of cyanid of mercury, chlorohydric
acid, chlorid of mercury, and sal-ammoniac are formed,
together with carbonic acid, nitrogen, and the chloric
cyanid, whieh escape in the gaseous form, while a yellow
oily liquid separates, which is heavier than water, and has
a pungent odor and caustic taste. The formula Cj^Cl^
is assigned to it; it is soluble in alcohol and ether, but in-
soluble in water, which however decomposes it into nitro-
gen, and carbonic and chlorohydric acids. By keeping,
it is spontaneously decomposed, with the separation of per-
chloric acetene C4C18. This compound is probably derived
82
Digitized
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498 ORGANIC CHEMISTRY.
from a combination of six molecules of cyanid, of which
the normal species will be C19H6Ne, a group which is the
type of a large and important class of polybasic salts, much
more stable than the ordinary cyanids.* The six atoms of
hydrogen are all replaceable by a metal, but two or three
atoms of the metallic elements are combined in such a way
as not to be recognized by the ordinary reagents, and like
the three atoms of hydrogen or chlorine in the acetic acids,
form a constant part of the acid. The second atom of sil-
ver in the fulminates, and the condition of the metals in
some of the tartrates, present analogous instances.
865. Ferrocyanids. — These salts may be represented by
C19(FeaM4)Na ; M being hydrogen or any metal. The
two atoms of Fe are so combined as not to be precipitated
by alkalies or sulphurets. The ferrocyanid of potassium is
formed with the separation of hydrate of potash, when
metallic iron or its oxyd is digested with a solution of cyanid
of potassium, hydrogen being evolved in the former case:
FeaOa+2CaKN = 2C,FeN+KaOfl, which, with H^ gives
2(UK)09. The cyanid of iron unites with another portion
of cyanid of potassium, to form the new salt Cia(FeaK4)N.
This is the ordinary source of all the cyanic compounds.
It is prepared on a large scale from the impure cyanid,
formed by the calcination of animal matters with carbonate
of potash, or by passing heated atmospheric nitrogen over
fragments of intensely ignited charcoal, impregnated with
the carbonate. *In both processes cyanid of potassium is
obtained, mixed with excess of the carbonate of potash. It
is dissolved in water and digested with oxyd of iron, or a
solution of protosulphate of iron is added, until the precipitate
at first formed is no longer dissolved by the cyanid. The
* Perchloric acetone is decomposed at a red heat into CI* and C4CI4,
or perchloric etherene. When this substance is exposed to the com-
bined action of chlorine and water, with exposure to the sun's rays, the
compound C4C1, is regenerated ; at the same time, a portion of it forms
with the elements of water, chlorohydric and chloracetic acids; C Clg-f-
2Ht0,=3flCl4-C4ClaH04. We have seen that by the aid of an amal-
gam of potassium, the chlorine of a chloracetate may be removed, and
the normal acetic acid formed. It has lately been found that when the
vapor of acetic acid is decomposed at a red heat, there are obtained,
besides carbonic acid gas and acetene, small portions of benzene, phenol,
and napthaline. These carbon compounds, high in the organic series,
may now by these reactions, be formed, from charcoal, through the cyanid*
Digitized
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FERROCYANIDS. 499
filtered liquid is then evaporated, when the ferrocyabid of
potassium separates in large translucent lemon-yellow tabular
crystals, containing SHaOfl, which is expelled by a gentle
heat. It is very soluble in water, but insoluble in alcohol,
and is not poisonous. This salt is known in the arts as tho
yellow prussiate of potash, and is employed in dyeing, in
the manufacture of prussian blue, and the fabrication of the
various cyanids. The preparation of Liebig's cyanid of
potassium, of the cyanates and sulphocyanates, by means of
this salt, has been already described. When it is carefully
dried and fused in a close iron vessel, the cyanid of iron is
decomposed into nitrogen and a carburet, and pure cyanid
of potassium is obtained, which may be crystallized by dis-
solving it in boiling alcohol of specific gravity -900. When
two parts of the dried ferrocyanid are heated with one of
chlorid of mercury, pure cyanogen gas is evolved, and by
boiling two parts of the crystallized salt with three of per-
sulphate of mercury and fifteen of water for a few minutes,
cyanid of mercury crystallizes on cooling. Distilled with
dilute sulphuric acid, the ferrocyanid yields hydrocyanic acid,
which is best prepared by this process.* Heated with an
excess of concentrated sulphuric acid, the ferrocyanid under-
goes a peculiar decomposition; the hydrocyanic acid evolved
in the presence of a strong acid takes up the elements of
water and yields ammonia and formic acid; but this last, by
concentrated sulphuric acid, is decomposed into carbonic
* A dilute acid is readily prepared by distilling a mixture of two parts
of ferrocyanid of potassium, one of sulphuric acid, and two of water, and
collecting the product in a receiver containing two parts of water, until
the liquid amounts to four parts. For this purpose the apparatus shown
in figure 415 is well calculated. This acid, from the presence of a trace
of sulphuric acid, is not liable to decomposition ; it contains fifteen or
twenty per cent of pure acid. To determine the amount of real acid
present, a weighed quantity of the distilled acid is added to a solution
of nitrate of silver, which should be in excess; the precipitate of cyanid
of Bilver is collected on a filter, dried at 212°, and weighed. Its weight
divided by 5 gives the amount of real acid in the specimen. Let us
suppose that 70 grains of the acid yield 80 of cyanid of silver, equal to
16 of real acid, 70 : 16 : : 100 : x, which equals 22*85 ; it then contains
22*85 per cent, of real acid. But if it is required to reduce it to any
standard, as one of three per cent, which is the ordinary medicinal acid,
then as this will consist of 97 of water and 3 of real acid, 3 : 97 : : 16 : x,
and x = 5x7*3 grains of water, which must be added to 16 of anhydrous
acid to reduce it to the standard. But as 70 grains of this acid contain
already 54 of water, it is obvious that we have to add 517*3 — 54 =. 463*3
grains of water to 70 grains of acid to reduce it to the required standard.
Digitized
byGoogk
500 ORGANIC CHEMISTRY.
oxyd gas and water, and the result is a copious evolution
of this gas in a pure state ; the residue contains bisulphate
of potash, and a double sulphate of ammonia and iron.
866. When a saturated solution of the ferrooyanid is
mixed with strong chlorohydric acid and agitated with ether,
a white crystalline matter separates, being insoluble in the
ethereal mixture; it is washed with ether and dried in vacuo,
and is ferrocyanic acid, C18(FeaH4)N6. Its taste is acid and
astringent : it is very soluble in water, and is decomposed
by exposure to the air, into hydrocyanic acid and a cyanid
of iron. When the potash salt is mixed with solutions of
salts of lime, baryta, and zinc, insoluble or sparingly soluble
salts are obtained, which are C11(FetKCas)N6, &c. The
copper salt is analogous in composition; it is insoluble in
water, and has an intense red-brown color, which makes
ferrocyanid of potassium a delicate test for that metal. With
a protosalt of iron a similar compound is obtained, which
is greenish-white, and rapidly becomes blue by exposure to
the air. With a persalt of iron a characteristic deep blue
precipitate is obtained, which is the pigment prussian blue.
It is Cu(Fe8fe4)Nfl, the replaceable iron being in the form
offerricum. The iron salt should be added in excess, or the
precipitate will contain a portion of potassium, like the pre-
ceding compounds. Prussian blue forms a light porous
mass of a deep violet-blue color, with a copper-red reflection :
it is insoluble in water and dilute acids, but when recently
precipitated is very soluble in solutions of oxalic acid and
tartrate of ammonia, forming deep blue solutions which are
used as writing-inks. Boiled with a solution of hydrate of
potash, peroxyd of iron separates, and ferrocyanid of potas-
sium is formed.
867. Ferrkyanids. — When chlorine is passed into a dilute
solution of ferrocyanid of potassium, the gas is absorbed, and
the liquid loses the power of precipitating persalts of iron.
On evaporating the yellow solution, a new salt is obtained in
beautiful deep red transparent prisms, which is known as
red prussiate of potash or ferrieyanid of potassium. This
salt contains (^(FegKg^N,, one atom of K having been
separated to form chlorid of potassium with the chlorine;
but the iron being in the state of ferricum, the salt becomes
Gia(fesKt)Nc, and the acid is C^fejH^Ng, and is tri basic.
It is obtained by decomposing the lead salt with dilute sul-
phuric acid. The ferrieyanid of potassium does not affect
Digitized
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NITROPRUSSIDS. 501
the persalts of iron, but gives with protosalts, a blue pre-
cipitate which is C13(fe8Fe8)N6 ; it has a finer hue than Ihe
ferrocyanid, and is known as TurnbulVs blue. When a
solution of the red prussiate is mixed with one of potash, in
the presence of organic matters, ferrocyanid is formed, and
the organic substance is oxydized by the oxygen set free.
This process is employed in calico-printing for discharging
colors. 2CUfe8K3)Nfl = 2Cta(FeaK8)N6 + 2(KH)Oa =
2CM(FeaK4)N6+Ha04=Ha0a+0a. Peroxyd of hydrogen
appears thus to be the oxydizing agent in this reaction, which
is very energetic; oxalates are converted by it into carbonates,
and a solution of chromic oxyd in potash, into chromate of
potash. The same view may be extended to oxydation by
chlorine: 2Cl+2HaOa=2HCl+Ha04.
868. Nitroprussids. — When a current of nitric oxyd gas
(N09, or rather Na04,) is passed through a heated solution of
ferricyanic acid, a reaction ensues which may be thus repre*
sented : 2011(feiHi)Ne = 20u(Fe,H8)Ni+N,O4 = 20,HN
+2C10FeaHaN6Oa ; the products being hydrocyanic acid, and
a new substance to which the name of nitroprussic acid has
been given. When either the red or yellow prussiate of
potash is heated with nitric acid so much diluted that no
nitric oxyd is evolved, nitroprussic acid may be obtained.
For this purpose 844 grains of crystallized yellow prussiate
are pulverized, and mixed in a capacious vessel with six
fluid-ounces of dilute nitric acid, of specific gravity 1-12;
the heat of a water-bath is applied until action commences,
and is then removed; the salt dissolves, and the liquid as-
sumes a dark coffee color, with a copious evolution of gas,
consisting of hydrocyanic acid and cyanogen, with some
nitrogen, resulting from a secondary decomposition. When
the solution is complete, the heat of a water-bath is again
applied until the liquid gives a dark green or slate-colored
precipitate with a protosalt of iron. On cooling, nitrate of
potash crystallizes, and the liquid is neutralized with car-
bonate of soda, and boiled ; a copious precipitate is formed,
and the filtered liquid is of a clear deep-red color, and con-
tains only nitrates of potash and soda, with the nitroprussid
of sodium. The nitrates are in part separated by concen-
tration and cooling, and on evaporating the remaining liquid
at a gentle heat, the new salt separates in ruby-red prisms,
resembling in appearance the red prussiate : its formula is
Cl0(Fe2Na2)N6O2; the crystals contain, besides, 2H202,
Digitized
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602 OEGANIC CHEMISTRY.
The potash salt is obtained by substituting carbonate 01
potash for the soda, but is more soluble. The nitroprussids
do not precipitate the persalts of iron, but yield with proto-
salts a salmon-colored precipitate which is C10(FeaFea)N8O„
and with copper salts a pale green insoluble nitroprussid
of copper. This is decomposed by a solution of baryta, and
gives a soluble baryta salt, which may be decomposed by
sulphuric acid, and the nitroprussic acid obtained in dark
*ed crystals, very soluble in water.*
If a solution of a nitroprussid is mixed with one of an
alkaline sulphuret, a magnificent purple liquid is obtained ;
this reaction is so delicate as to detect the smallest trace of
a soluble sulphuret. The color soon fades by standing, and
the solution then contains ferrocyanid, sulphocyanid, and
a nitrite, while nitrogen, hydrocyanic acid, oxyd of iron, and
sulphur are set free. Nitroprussid of sodium forms a crys-
talline compound with hydrate of soda which is decomposed
by boiling; nitrogen gas and peroxyd of iron, with ferro-
cyanid, nitrite and oxalate are the products.
869. The action of cyanid of potassium upon salts of
chromium, manganese, and cobalt, gives rise to salts which
correspond to the ferricyanids, the metals being in the same
equivalent as in the sesquisalts. The compounds corre-
sponding to ferrocyanid have not been obtained : when pro-
tocyanid of cobalt is dissolved in cyanid of potassium,
sesquicyanid of cobalt, cyanid of cobalticum CacoN is formed,
and potassium is liberated, which, decomposing the water,
forms hydrate of potash, evolving hydrogen gas, 4CaCoN+
2CaKN=6C9coN+Kfl. The cobaltic cyanid with another
* The formula here given for the nitroprussids is that proposed by M.
Gerhardt, and corresponds best with the original analyses of the dis-
coverer, Dr. Playfair, and even with the subsequent results of Mr. Kyd,
whose proposed formula for the soda salt, Cy,Fe9NaaNO, is not admissible
unless it is doubled. There are many reasons for believing that carbon
replaces sulphur and oxygen, somewhat as nitrogen does hydrogen, and
then 04Nt and C4Na become equivalent to each other, while peroxyd
of hydrogen Ha04 and nitrous acid NH04 correspond to cyanic acid,
NII(CaOa), and hydrocyanic acid CaHNf to CJL,, and to water 09Hg.
The Ditroprussids are then ferrocyanids which have lost H^ becoming
bibasic, and under the influence of 04Nahave exchanged Cy=CaN for
its equivalent OaN. The formula will then be written {Gy^O^y^e^v^
ms (^loOaXFeaNaJNg. A similar view may be extended to a great number
ef compounds ; nitrobenzene, for example, is benzoilol in which N replaces
a and Oa replaces Ca; thus, (ClaOa)(H,N)Oa, corresponding to CuU80r
Digitized
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ACIDS OP THE URINE AND BILE. 503
portion of cyanid of potassium forms the cobalticyanid of
potassium C19(co8K3)NB.
Platinum has a great tendency to form a platinocyanid,
and when the metal in its spongy form is heated to redness
with ferrocyanid of potassium, the mass yields to water the
new salt, which crystallizes in long transparent rhomboidal
prisms, yellow by reflected and blue by transmitted light :
it is C^PtgK,)!^. By decomposing the mercurial salt with
sulphuretted hydrogen, platiiwcyanic acid C19(Pt8H8)N6 is
obtained ; it is very soluble, and crystallizes in golden-yel-
low prisms, with a copper-red reflection. The baryta salt
forms short lemon-yellow prisms, which are greenish by
reflected light.
870. The other complex cyanids have been but little studied :
one containing silver is obtained when the oxyd, chlorid, or
cyanid of silver is added to a solution of cyanid of potassium.
The argentocyanid of potassium is very soluble, and forms
colorless tabular crystals ; its composition is represented by
C^AgjKg)^. It is much less stable than the previous
compounds ; the silver is not precipitated by chlorids, but
strong acids throw down insoluble cyanid of silver, and set
free hydrocyanic acid. With a salt of lead, "a precipitate is
obtained in which lead replaces the potassium. The silver
«alt is used in electro-plating, and is generally prepared by
dissolving oxyd or chlorid of silver in a solution of cyanid of
potassium, hydrate of potash or chlorid of potassium being
formed at the same time. Oxyd of silver decomposes even
the ferrocyanid to form the new double salt. In the process
of electro-silvering, the silver being liberated at one pole,
the potassium and cyanic elements are set free at the other,
and this pole being terminated by a plate of silver, the metal
is dissolved as fast as it is deposited at the other pole, thus
preserving the strength of the solution.
Oxyd of gold is readily soluble in cyanid of potassium, and
yields a double salt which is used in a similar manner to the
last for the process of electro-gilding. A solution of cyanid
of potassium may be used to remove from thejskin or from
linen, the stains produced by salts of silver, gold or mercury.
Acids or the Urine and Bile.
871. These animal secretions contain several peculiar
tzotized acids, which are very interesting from their meta*
Digitized
byGoogk
$04 ORGANIC CHEMISTRY.
morphoses : those of urine are named the uric and hippui u,
acids.
The hippuric acid is found principally in the urine of herbi-
vorous animals ; that of stall-fed horses and cows contains
a considerable quantity. To obtain it, the fresh urine may
be mixed with chlorohydric acid in the proportion of four
ounces of the acid to a gallon, and allowed to stand for
some hours in a cool place. A crystalline matter which is
deposited is impure hippuric acid : it is separated, redis-
solved by boiling in water with excess of milk of lime, and
a little animal charcoal to decolorize it : the filtered hot
solution of hippurate of lime is then mixed with a slight
excess of chlorohydric acid, and hippuric acid separates on
cooling in beautiful white prisms. The fresh urine may
also be heated to ebullition with milk of lime, and after
separating the precipitate thus formed, boiled down to
one-tenth, and then precipitated by chlorohydric acid : in
this way a larger portion is obtained, (from forty to fifty
grains from a pound.) Hippuric acid is very soluble in
boiling water, but requires about 400 parts of cold water
for its solution. It is monobasic and is represented by
C^HgNOg ; when boiled with peroxyd of lead it is converted
by oxydation into benzamid, carbonic acid and water :
C„H9NOa+08 = C14H7N09+2Cjl04+HaO!ll. By the action
of nitrous acid, hippuric acid is decomposed like aspartic
acid, and yields water, nitrogen, and a new acid called ben-
zoylycollic acid : it is Ca6HlBOl6, two equivalents of hippu-
ric acid being concerned in the reaction. Benzoglycollic
acid is bibasic ; it is sparingly soluble in cold water, but
dissolves readily in boiling water, alcohol, and ether. It
fuses below 212° F., and at a higher temperature is decom-
posed, benzoic acid subliming. When boiled with dilute
sulphuric acid, it is decomposed into benzoic acid, and a
new bibasic acid called the glycoUic9 C8Ha013. This is homo-
logous with lactic acid, to which it bears a very close re-
semblance, and appears to be identical with the acid formed
in the preparation of the fulminates. Beuzoglycollic acid
yields two equivalents of benzoic, and one of glycollic acid :
C3eH18018+2H,0, = 2C.HA+C AO„.
872. When hippuric acid is boiled with a strong acid, it
is decomposed into benzoic acid and a sweet crystalline
substance, which was first obtained by the action of sulphuric
acid upon glue or gelatine; it has hence received the nam*
Digitized
byGoogk
URIC ACID. 605
* of sugar of gelatine, glycycoll, or glycocine, (from gluteus sweet,
and kolla glue.) It is best obtained by boiling bippurio
acid for balf an hour, in ten parts of a mixture of sulphuric
acid diluted with twice its volume of water. On cooling,
benzoic acid separates, and after removing the sulphuric
acid by saturating it with carbonate of lime, glycocine re*
mains in solution, and may be purified by crystallization from
dilute alcohol. Glycocine forms colorless prismatic crystals
which are soluble in four or five parts of water, but are in-
soluble in pure alcohol ; its taste is sweet, like grape sugar.
Its formula is C4HsN04, and its formation from hippurio
acid is thus represented; C18H0NO6+HaOa==C14H6O4-f-
C4H5N04. It is homologous with alanine, and is, like it, an
organic base, forming salts which crystallize beautifully.
An atom of hydrogen in it may be replaced by a metal, and
species like C4(H4Cu)N04 are obtained, whish saturate
acids, like the normal glycocine. Alkargen, C4HsAs04, the
product of the oxydation of alkarsine, is glycocine, in
which arsenic replaces nitrogen. By the action of nitrous
acid, glycocine is decomposed and yields glycollic acid:
2C4H8N04+2NH04=Na+2HaOa+CsHsOia.
Benzoglycollic acid may be viewed as a coupled acid, in
which two equivalents of the monobasic benzoic have re-
placed Ha in the bibasic glycollic acid, with the elimination
of 2H3Oa ; it is therefore itself bibasic. When a mixture of
benzoic and lactic acids is fused together, water is evolved
and the homologue of benzoglycollic acid, corresponding to
lactic acid, is obtained : it is O^H^O^, and is readily decom-
posed by strong acids into benzoic and lactic acids.
873. Uric or lithic acid exists in the urine of carnivo-
rous animals, and in that of man — in the last associated with
hippuric acid. The solid white urinary excretions of birds
and serpents are composed almost entirely of urate of am-
monia. The urine of the boa or other serpents is dissolved
by boiling in a solution of hydrate of potash, ammonia
being evolved. A current of carbonic acid gas is then
passed through the liquid, which throws down a sparingly
soluble acid urate of potash. This is washed with cold
water to remove impurities, and redissolved in a hot dilute
solution of potash : from the warm liquid chlorohydrio
acid separates a gelatinous precipitate, which soon changes
into a white crystalline powder of pure uric acid. The urio
cid may be separated from the dung of pigeons or other
Digitized by VjOOQ IC
50ft ORGANIC CHEMISTRY.
birds by a solution of borax in 100 parts of boiling water:
the acid is thrown down from this by chlorohydric acid, and
may be dissolved in potash, and purified by the process
already described.
Uric acid is soluble in 2000 parts of hot water, and has
feeble acid characters : it is represented by C^H^^Og, and
is bibasic; the urates, like the acid itself, are sparingly
soluble. The products of the decomposition of uric acid are
numerous and interesting. When boiled with water and
peroxyd of lead, carbonic acid gas is formed, and a substance
called allantoin, which exists in the amniotic liquid of the
cow, and in the urine of young calves. Its formula is
C8H8N4Oe ; allantoin forms brilliant colorless prisms, soluble
in 160 parts of cold water. The further action of peroxyd
of lead decomposes it into an oxalate and two equivalents
of urea, C3H6N406+2HaOa+Oa=C4H3Os+2C2H4NaO,^
Boiled with acids it fixes the elements of one equivalent of
water, and forms one equivalent of urea, and allanturic acid
C6H4N806; this is very soluble and deliquescent. When
boiled with baryta-water, allantoin is completely decomposed
into an oxalate and ammonia; C8H6N4Ofl+4(BaH)Oa-|-
H,09=2C4Ba,08+4NHs.
874. When uric acid is mixed with warm chlorohydric
acid and chlorate of potash is gradually added, the acid is
dissolved and oxydized at the expense of the oxygen of the
chloric acid. It is converted by this process into urea and
a new compound, alloxan C8H4Na010. This substance is also
formed when uric acid is added in small portions to nitric
acid of specific gravity 1-43; it dissolves with the evolution
of nitrous fumes, mixed with nitrogen and carbonic acid
from a partial decomposition of the urea, and on cooling,
alloxanis deposited; C10H4N406+2HflOfl+Oa=C3H4Na03+
CsH4Na010. Alloxan crystallizes in small colorless brilliant
rhomboidal crystals, with a vitreous lustre, which are an-
hydrous; or in large prisms which contain water, and are
efflorescent. It is very soluble in water, and its solution
gives to the skin, after some time, a purple stain and a
nauseous odor. In contact with bases, alloxan combines
with HaOa to form a feeble bibasic acid, called the alloxanic
acid. Boiled with a solution of baryta or with acetate of
lead, alloxan fixes the elements of water and yields urea and
a salt of mesoxalic acid, which is soluble, quadribasic, and
represented by Ca^O^. If a solution of alloxan is gently
Digitized
byGoogk
URIC ACID. 507
heated with peroxyd of lead, carbonic acid gas is disengaged,
and urea remains in the solution, mixed with insoluble oxa-
late and carbonate of lead. Alloxan, with water and oxygen,
yields urea, carbonic acid, and oxalic acid; C8H4Na010+
H»0«+Oa= CaH4Na0a+Ca04+C4Ha08. The carbonate of
lead in the residue results from a further oxydation of a
portion of the oxalate by the peroxyd.
875. When sulphuretted hydrogen is passed through a sola*
tion of alloxan, sulphur is deposited, together with a white
crystalline substance named alloxantine ; it is C^H^N^O^
and is formed by the combination of two equivalents of alloxan,
which fix at the same time Ha. When a solution of alloxan
is mixed with chlorohydric acid, and a fragment of zinc is
added, the hydrogen from the decomposition of the acid is
not evolved, but unites with the alloxan to form alloxantine,
which crystallizes upon the zinc. Alloxantine is also formed
when a solution of alloxan is boiled with dilute sulphuric or
chlorohydric acid, and is deposited on cooling ; an equivalent
of water is decomposed, and H3 unites with two equivalents
of alloxan to form alloxantine, while the Oa oxydizes another
equivalent of alloxan, as in the case of peroxyd of lead, and
forms oxalic and carbonic acids and urea, which last in
presence of the acid, is decomposed into ammonia and car-
bonic acid. The decomposition of water in this reaction is
analogous to that of sulphuretted hydrogen in the previous
process. This substance is sparingly soluble in water : it
appears to possess feeble acid properties, but is at once de-
composed in contact with bases. When alloxantine is
warmed with twice its volume of water, and a little nitric
acid is added, solution takes place, with the evolution of
nitric oxyd ; the filtered liquid mixed with a few drops of
the acid, to oxydize any excess of alloxantine in solution,
deposits on cooling pure alloxan; Cl8 H10N40fl0+ Oa= 2 C8H4
Na0104-H9Oa. The most advantageous way of preparing
alloxan is to dissolve uric acid in warm, somewhat dilute
chlorohydric acid, with the aid of one-fourth its weight of
chlorate of potash, to precipitate alloxantine by passing
sulphuretted hydrogen throfigh the diluted solution, and
convert it into alloxan by the above process.
876. A boiling aqueous solution of alloxantine is still
further decomposed by sulphuretted hydrogen ; sulphur
separates, and dialuric acid is formed ; this is C8H4Na08, and
is monobasic; its ammonia salt is colorless, but becomes
Digitized
byGoogk
508 ORGANIC CHEMISTRY.
blood-red on drying. Dialurio acid differs from alloxan by
0* and its potash salt is formed by a process of de-oxydation
when cyanid of potassium is added to a solution of alloxan.
By exposure to the air, this acid absorbs water and oxygen,
and is changed into a dimorphous form of alloxantine.
Alloxantine contains the elements of alloxan, dialuric acid,
and an equivalent of water ; when its solution is mixed with
one of sal-ammoniac, alloxan is formed, chlorohydric acid set
free, and an insoluble crystalline substance separates, to
which the name of uramile is given ; it is the amid of dia-
luric acid, being C8H5N8Oe. An equivalent of alloxantine,
C«H10N4O„+HCl.NH,=C,H4NsO10+C8HsN,O,+H91+
2H8Ofl. When a solution of alloxan is heated to boiling
with sulphite of ammonia, it deposits, on cooling, brilliant
plates of a new salt, the ihionurate of ammonia. Thionurio
acid is bibasic, and contains the elements of alloxan, am-
monia, and sulphurous acid ; it is CsH7N8Ss014. When its
solution is heated to boiling, it is completely decomposed'
into uramile and sulphuric acid, C8H5N808+SaHa08 ; but
if previously mixed with sulphuric acid and evaporated in
a water-bath, dialuric acid and sulphate of ammonia are
obtained.
877. The solutions of uric acid in nitric acid are colored
of a beautiful purple by ammonia; and alloxantine in an
ammoniacal atmosphere, or solutions of uramile in ammonia
or hydrate of potash, absorb oxygen from the air, and assume
the same purple color. If, to a nearly boiling solution of
alloxan, one of carbonate of ammonia is added in slight
excess, there is a violent effervescence from the escape of
carbonic acid gas, and the liquid assumes so deep a purple
hue as to be almost opaque. As it cools, delicate square
prisms are deposited, which are garnet-red by transmitted,
and golden-green by reflected light ; their powder, under a
burnisher, assumes a green metallic brilliancy. This
beautiful substance is named .murexid, in allusion to the
murex which furnished the purple dye of the ancients ; it
is slightly soluble in cold water, and colors it purple. Crys-
tals of it are also obtained when uramile and oxyd of silver
are boiled with water containing a little ammonia ; the silver
is reduced, and the filtered purple solution deposits murexid
on cooling. The probable formula of murexid is CgH^N^^
corresponding to the amid, or rather nitryl of alloxaoic acid.
Alloxanate of ammonia, CaHflNaOia.2NH3—4H808=^C8H4
Digitized
byGoogk
CHOLIO ACID. 509
N404. A solution of murexid in hot water gives a red
precipitate with nitrate of silver; its solution heated to
boiling with sulphuric acid, yields a precipitate of uramile
and alloxan, while alloxan tine and sulphate of ammonia re-
main in solution.
When uric acid or alloxan is boiled with an excess of
strong nitric acid, carbonic acid gas is evolved and para-
banic acid formed ; it is CaH9Nfl0a, and is bibasic and very
soluble. When its ammonia salt is heated to boiling, it
fixes Il^Oa, and is converted into oxalurate of ammonia.
The addition of chlorohydric acid to a solution of the new
salt separates the oxaluric acid as a sparingly soluble powder,
which is represented by CaH4Na0g. When its aqueous
solution is boiled, it is converted into oxalic acid and urea,
CiH4Nfl08+Ha0fl=C4Ha08+CflH4Na0fl.
878. The action of chlorine upon the alkaloid caffeine,
produces, among other products, a feebly acid crystalline
substance, sparingly soluble in water, to which the name
of amalic acid has been given. It closely resembles allox-
antine, and is homologous with it, being C^H^^O*, ; the
two differ by 4CflHa. When amalic acid is moistened
with water and exposed to the action of air and ammonia,
it is converted into a reddish-brown substance, which, by
solution in hot water, yields red crystals, scarcely distin-
guished from murexid by their characters. They are named
murexoine, and are probably the murexid of this series, of
which the other members have not yet been studied.
879. Cholic Acid. — The bile of animals is a solution of
the soda or potash salts of two azotized acids, one of which
contains sulphur. % When ox-bile is evaporated to dryness
and dissolved in alcohol, the careful addition of ether pre-
cipitates first the salt of the sulphur acid, and by a further
addition of ether, aided by cold, the soda salt of the dis-
solved cholic acid may be obtained in crystals. On adding
sulphuric acid to their aqueous solution, the acid separates
after some time in delicate white silky crystals, which have
a bitterish sweet taste, and are very sparingly soluble in
water. Cholic acid is monobasic, and is represented by
CjgH^NO^. When boiled with a solution of baryta, it is
decomposed like hippuric acid into glycocine and a new
acid, containing no nitrogen, which is called cholalic acid,
C^H^NO^+H^O^C^NO^C^H^O.o, which is the
formula of cholalic acid. It forms colorless octahedral
Digitized
byGoogk
510 ORGANIC CHEMISTRY.
crystals, which require 4000 parts of cold water for then
solution, but are very soluble in alcohol. When exposed
to heat, or when boiled with strong chlorohydric acid, it u
converted successively into chofoidie acid and an almost
insoluble resinous body, dyslysine, both of which are formed
by the loss of the elements of water ; dyslysine is C^H^Og.
When cholic acid is heated with a dilute acid, it loses H^O^
and yields ckoUmic acid, C5fH41N010, which, by boiling, is
decomposed into glycocine, and choloidic acid or dyslysine.
880. Acetate of lead precipitates the cholic acid from bile
which has been purified by solution in alcohol, but leaves
in solution the sulphuretted acid, to which the name of
choleic acid is given ; the bile of sheep, and of some fishes
is almost entirely composed of choleates, and that of the dog
is pure choleate of soda. Choleic acid resembles the cholic
acid, but both it and its salts are more soluble in water.
Its formula is C^H^NO^Sg ; when boiled with a solution
of baryta, it is decomposed like the cholic acid, and yields
cholalic acid, and in place of glycocine, a neutral body
named taurine, which is crystalline, soluble in water and
alcohol, and contains C4H7NOftSfi. The action of acids
yields taurine and cholalic acid, and the spontaneous putre-
faction of recent ox-bile, which is mixed with the mucus of
the gall-bladder, affords similar results; acetic and allied
acids, probably from the decomposition of glycocine, accom-
pany the taurine, which is itself decomposed at a later stage
of the process, sulphurous and sulphuric acids being formed.
881. The bile of pigs contains a peculiar acid to which
the name of hyocholic acid is given : it is C^H^NO^, and
is homologous, not with cholic, but with cholonic acid, dif-
fering from this by C,Ha: boiled with baryta water, it yields
glycocine and hyocholalic acid} homologous with cholalic
acid : by chlorohydric acid it is converted into glycocine and
a homologous species of dyslysine: C^H^NOaj^CJIjNC^
+CS0HMO,.
Bile contains, besides these salts, a portion of fat, a yel-
low coloring matter, and a neutral crystalline body resem-
bling spermaceti in appearance, to which the name of
cholesterine is given : it often forms concretions in the gull-
bladder, known as biliary calculi. The formula C^H^O, is
assigned to it.
Digitized
byGoogk
NITROGENOUS NUTRITIVE SUBSTANCES. 511
NUTRITIVE SUBSTANCES CONTAINING NITROGEN.
882. Under this head may be described a class of sub*
stances which are common to plants and animals, and sustain
a very important part in the economy of nutrition. The
seeds and juices of all plants, in addition to the starch,
sugar and lignine always present, contain peculiar substances
which, although unlike in form and solubility, have a general
similarity of composition with each other, and with the
muscular tissue of animals. The relations between these
bodies may be said to be analogous to those between starch,
gum, dextrine, and lignine. In both, the differences are to
be considered as in part depending upon organization, and
in part upon that molecular arrangement, which constitutes
a species of isomerism. As lignine and starch may be con-
verted into dextrine, and as both dextrine and gum, by
acids, yield glucose, so these different azotized substances
may be converted one into another. To these bodies the
general name of protein compounds has been given, from
proteuoy I take the pre-eminence, in allusion to their import-
ance in the vital economy.
883. The muscle or flesh of animals is called fibrin, and is
an organized form of protein ; fibrin also separates from the
blood during coagulation, and is, when pure, a white tasteless
mass, insoluble in water, and becomes horny and translu-
cent by drying. It dissolves in acetic and dilute chloro-
hydric acids, in warm solution of sal-ammoniac, nitre, and
several other salts, and is separated from them by heat in
an insoluble amorphous form.
The serum of the blood and the white of eggs contain
in solution a large quantity of a protein compound, which
is similar in its characters to dissolved fibrin, and coagulates
by a heat of 158° F. : it is called albumin, and is nearly
pure in the white of eggs. Albumin when coagulated by
beat is insoluble in water, and resembles fibrin in its chemi-
cal properties ; milk contains another soluble form of pro-
tein, which is not coagulated by heat, but is at once sepa-
rated in an insoluble condition by a dilute acid; it has
received the name of casein, and is nearly pure in the curd
of skimmed milk. Casein appears to be insoluble in water
when pure, and to be held in solution in milk by a small
portion of soda : the albumin of the blood is by the action of
a solution of potash converted into a form resembling casein
Digitized
byGoogk
612 ORGANIC CHEMISTRY.
884. When a paste of wheat flour is washed with water
until all the starch is removed, a tenacious gray substance
remains, which dries into a horny mass, and which, though
not possessed of the organized structure of muscular fibre, is
soluble in acetic acid, and is chemically identical with fibrin:
it is called glutin. The water from the washing of the
paste, from which the starch has separated by repose, and
the juices of many vegetables, yield by heat an insoluble
protein body, which is vegetable albumin. When beans or
peas are bruised with water, a large quantity of protein k
dissolved, and may be precipitated by the addition of an
acid. It is called legumin, or vegetable casein.
885. When any one of these substances is dissolved in a
moderately strong solution of hydrate of potash, and heated
for some time to 120° F., the addition of acetic acid in slight
excess, separates a white flocculent matter, which when washed
with water and dried, is a yellowish brittle mass, soluble in
acetic acid, but insoluble in water and alcohol. It is pro-
tein in a state of comparative purity, and has nearly the
same composition, from whatever source it is obtained. In
their natural state, the protein bodies contain variable and
often considerable quantities of mineral matter in a state of
combination or intimate mixture. The curd of milk yields,
when burnt, several per cent of ashes, consisting principally
of phosphate of lime. The different protein compounds
also contain small, but variable proportions of sulphur and
phosphorus in combination with the organic elements, pro-
bably replacing oxygen and nitrogen in a portion of the
protein; and the sulphur remains after solution in potash
and precipitation by acetic acid. If to a solution of any
protein body in potash, a little acetate of lead is added, and
the solution is heated to boiling, it becomes black from the
formation of sulphuret of lead ; but even by ebullition it is
difficult to decompose the whole of the sulphur compound.
The amount of sulphur generally varies from 1 to 1*5 per
cent., but the protein from cows' horns and hoofs contains,
according to Mulder, from 3*4 to 4-6 per cent, of that element.
The proportion of phosphorus in the different forms of protein
also varies from a trace, to -8 per cent., and in vegetable
casein it rises to 2*4 per cent : it is sometimes absent.
886. The facility with which the protein bodies are altered
by spontaneous decomposition, and by different reagents,
renders it very difficult to fix their exact composition. If
Digitized
byGoogk
PROTEIN. 51g
we suppose the sulphur to replace a portion of the oxviren
Che formula C^H^O, may be assigned as expressin/verv
closely the composition of protein. The greatest amount of
sulphur present in any variety of protein, scarcely amounts
to one equivalent : the normal protein appears to be inti-
mately mixed with a sulphuretted compound, which has
probably the same equivalent composition in other respects
as protein itself: an analogous case occurs in the two acids
of the bile, which can scarcely be separated from each other
by any known difference in properties. The phosphorus
which is sometimes present, may belong to a body in which
that element replaces nitrogen, wholly or in part. There
are other organic matters in the brain and the blood, which
contain phosphorus in a similar combination; but it is more
probable that in the protein bodies, it exists as phosphate of
887. The following numbers give the proportions of
carbon, hydrogen, nitrogen, and oxygen, required by the
above formula, and the results of an analysis of the protein
from albumin, and one of fibrin. The amount of oxygen
equivalent to the sulphur present, is given on one side, and
added to the quantity of oxygen, for the purpose of com-
panson : — #
AMtdjten by Mulder.
Calculated. Protein. Fibrin.
Carbon 53-93 53-7 52*7
Hydrogen 6*36 6*9 6*9
Nitrogen.. 15.73 14*4 15-4
Oxygen 23-98 23-6 ) 9 , 23-5 ) 0 . 0
Sulphur. 1-4=0-7 1 U 3 1-2=0-6 j 2iZ
Phosphorus »3
100-00 100-0 100-0
The results of different analyses of protein from other
sources, show still greater variations in composition, ono
reason of which is the want of definite chemical characters
by which we may be able to separate it from any admixture
of foreign bodies. The above formula, however, coincides
better than any other, with the analyses of the purest forms
of protein : protein is, according to it, an amid, or rather a
mtryl of cellulose; C84Hao030+3NHaa=6HaOfi+Ca4H1?N8
U8. It should therefore under proper conditions assimilate
water, and yield ammonia, and a body belonging to the
•eries of cellulose, dextrine, or glucose ; in fact, when protein
33
Digitized by VjOOQ IC
614 ORGANIC CHEMISTRY.
is dissolved in strong heated cblorohydric acid, it is com*
pletel y decomposed into ammonia, which forms sal-ammoniac,
and a brown insoluble matter identical with that produced
by the alow decay of woody fibre, and derived from cellulose
by the loss of the elements of water. A similar body is
produced from grape sugar by the action of chlorohydric acid.
The muscular tissue is insoluble protein in an organized
condition, and sustains a similar rank in the animal structure
to that of cellulose in the vegetal, while albumin and casein
are soluble unorganized forms of protein, and may be com-
pared to dextrin and gum.
888. The action of hydrate of potash aided by heat,
upon the different forms of protein, evolves a great deal of
ammonia mixed with hydrogen, and probably several vola-
tile bases, and the residue contains, among other substances,
salts of acetic, butyric, and valeric acids, and two crystal-
line azotized bodies, named leucine and tyrosine. The former
has the formula C18H18N04; it is homologous with glyco-
cine and alanine, and is an organic base resembling these in
its characters. Tyrosine is C^H^NOg. These two bodies
are also obtained as products of the action of sulphuric acid
upon protein. The protein bodies when mixed with water
and kept in a warm place, readily undergo spontaneous
decomposition, and evolve a disagreeable odor, becoming
putrid. Fibrin is at first converted into a soluble form
resembling albumin, hydrogen gas and ammonia are evolved,
and there remain in solution ammoniacal salts of butyric and
valeric acids, besides leucine and tyrosin, and a portion of
undecomposed protein.
889. When any form of protein is distilled with a mix-
ture of bichromate of potash and sulphuric acid, the latter
not being in excess, the protein is oxydized by the chromic
acid, and a great variety of volatile products are obtained;
among them are prussic acid, or formic nitryl, and the nitryl
of valeric acid, together with bitter-almond oil, benzoic acid,
and the formic, propionic, butyric, and valeric acids. When
peroxyd of manganese is substituted for the bichromate, with
an excess of sulphuric acid, the nitryls are not obtained, but
besides bitter-almond oil, and the acids already mentioned,
tho acetic and caproic acids, together with the acetic, pro-
pionic, butyric, and valeric aldehyds. In the latter process
the residue contains salts of ammonia, and the acids may
result from the decomposition of previously formed bodies
Digitized
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PROTEIN. 515
liko leucine : this, when distilled with a mixture of oxyd
of manganese and sulphuric acid, yields carbonic acid and
valero-nitryl, and the latter by an excess of acid is con-
verted into valeric acid aucl ammonia.
The destructive distillation of the protein bodies yields
a large amount of carbonate of ammonia, and a number of
volatile oily bases, some of which are homologous with
ammonia, besides water and inflammable gases, and leaves
a bulky charcoal very difficult of combustion, which con-
tains several per cent, of nitrogen, and is perhaps a mixture
of carbon with something analogous to paracyanogen.
890. When fibrin or casein is kept for some time in a cool,
dark, and moist place, it undergoes a decomposition which
results in its partial or entire conversion into a fusible fat,
resembling butter and easily saponified, which has not yet
been minutely examined. It is said to have a sweet taste,
and to be readily volatile; if such is the case, it is not
improbable that the product is an ether of some fatty acid or
acids. This change is observed in the preparation of some
kinds of cheese, and may be supposed to consist in the
fixing of the elements of water, the separation of the nitro-
gen in the form of ammonia, and a great portion of the
oxygen with some of the carbon, in the form of carbonic
acid gas. It is accompanied with the development of a
great number of mycodermic plants, or moulds, which
appear to be nourished by the evolved gases.
891. The protein bodies not only undergo spontaneous
decomposition themselves with great facility, but, under cer-
tain conditions, induce changes in a great variety of organio
substances. The action of casein in converting sugar into
acetic and lactic acids, and this latter into butyric and car-
bonic acids and hydrogen, and the conversion of sugar into
alcohol and carbonic acid have already been described.
Diastase which changes starch into sugar, and emulsine
which effects the decomposition of salicine and amygdaline,
are forms of protein or an allied substance.
If a minute portion of putrefying fibrin is added to a solu-
tion of leucine, this substance is decomposed and valerate of
ammonia remains dissolved : the spontaneous decomposition
of urea, hippuric acids, and the acids of the bile, in the pre-
sence of the putrescent animal matters of the secretions, are
similar instances. These phenomena may be included under
the general name of fermentations ; although the term should
Digitized
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616 ORGANIC CHEMISTRY.
be perhaps more restricted in its signification, and exclude
those processes in which diastase and emnlsine are the agents.
892. The alcoholic fermentation has been the one most
carefully studied; it is produced by decomposing casein or
fibrin, as well as by yeast. Yeast, when obtained from fer-
menting beer, has a chemical composition allied to protein,
and resembles it in its properties ; it is found under the
microscope to be completely organized, and to consist of two
minute species of fungus, which seem to be always produced
and propagated in a solution of sugar, when undergoing the
vinous fermentation : the presence of decomposing protein
in a sugar solution, appears to excite fermentation by afford-
ing the conditions necessary to the development and nutri-
tion of these fungi. These bodies are figured in § 695. One
of the species in yeast appears to be more especially connected
with the vinous fermentation, and, being much greater in size,
may be separated by filtration from the other, which is regard-
ed as the fungus of the lactic and butyric fermentations; this
last also appears in the conversion of casein into fat, and it pro-
duces the decomposition of urea into carbonic acid and ammo-
nia, a change which is rapidly effected in the presence of yeast.
The acetic fermentation is characterized by a distinct fungus.
The power of yeast or any form of protein to produce
these organic changes, is destroyed by boiling water, by
chlorid of mercury, arsenious acid, salts of iron, zinc, alka-
lies, mineral acids, or by oil of turpentine or kreasote.
Yeast may be dried at a gentle heat, and regain its activity
when moistened with water, but if when dried, it is finely
divided by trituration, so as to destroy the fungi, it is inert.
It may be said that whatever is fatal to the vitality of the
fungi, destroys at the same time the activity of the fer-
ment. The bodies just mentioned are known to act as
antiseptics, preventing putrescence, but it is not improbable
that all cases of putrefaction belong to the same class of
phenomena as these fermentations.
893. From the constant connection between the develop-
ment of certain fungi and different chemical changes, it is
supposed by many chemists that they are the agents in the
process df fermentation, which is one essentially vital, and
that the fungi decompose the organic bodies, perhaps by a
sort of absorption and subsequent excretion.
The action of boiling water and of antiseptics, destroys
the power of diastase and emulsine to act upon starch and
Digitized
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GELATIN. 617
amygdaline. I am not aware whether in these reactions, the
development of fungi has been noticed. The phenomena
most analogous to fermentations are such as those in which
a small portion of sulphuric acid converts a large amount
of alcohol into ether, or olefiant gas, and water, or where the
same acid converts dextrine into sugar, or to the spontaneous
decomposition of a solution of urea at an elevated tempera-
ture : in all these cases, the influence of vitality is evidently
excluded. Our knowledge of chemical dynamics appears
as yet inadequate to explain the part which fungi play in
many processes, or to draw the distinction between those
changes which appear to be effected through their agency,
and those which are purely chemical.
894. Gelatin. — This substance exists in many animal tis-
sues, as the skin, cellular membranes, tendons, and ligaments,
and forms the frame-work of the bones ; in this organized
form it is insoluble in cold water, but by boiling it dissolves,
and the soluti:& forms on cooling a firm jelly, which is very
characteristic of gelatin; this, when dried, constitutes
ordinary glue. The substance known as isinglass, is the
dried air-bladder of certain fishes, and is a nearly pure gela-
tinous tissue, which is soluble in boiling water. A so-
lution of gelatin is precipitated by salts of mercury, and
yields a copious insoluble precipitate with an infusion of
nutgalls, or a solution of tannic acid ; the insoluble tissues
absorb tannic acid from its solutions to form the same com-
pound, which constitutes leather. The process of tanning
consists essentially in immersing the prepared skin in an
infusion of oak or hemlock bark, by which it is saturated
with tannin, and becomes incapable of putrefaction, insoluble
in boiling water, firm, elastic, and, to an extent, water-proof.
895. Gelatin undergoes putrefaction like protein, and
is susceptible of exciting fermentation ; the products of its
decomposition by oxydation, and by the action of acids and
alkalies, are the same with those of protein. It however
yields, in addition to leucine, its homologue, glycocine
C4H5N04, which was first described by the name of sugar
of gelatin. When a solution of gelatin is boiled for many
hours with dilute sulphuric acid, a large quantity of sulphate
of ammonia is formed, and the liquid contains sugar, which
yields alcohol and carbonic acid by fermentation. This
reaction leads to the supposition that, like protein, it is
nearly allied to dextrin or glucose, and the formula
Digitized
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618
ORGANIC CHEMISTRY.
C^H^N^g, which accords closely with the results of various
analyses of soluble and insoluble gelatin, makes it corre-
spond to an amid formed from one equivalent of glucose and
four of ammonia by the loss of eight of water. 01B4HJH084+
4NH8=C?tHfl0N4O8+8HaOfl. The decomposition by sul-
phuric acid will then consist in the assimilation of water,
and the regeneration of glucose and ammonia.
The gelatinous substance obtained from cartilage differs
■omewhat in its composition and properties from ordinary
gelatin, and has been distinguished by the name of chondrin.
THE BLOOD.
896. This substance when recent is a homogeneous,
slightly viscid, red fluid, of a saltish taste and a peculiar odor.
When examined under a microscope it is found to consist of
a transparent and nearly colorless liquid, in which are floating
an immense number of small red bodies, ("blood corpuscles,)
varying in form and size in different animals, also a small
and variable proportion of colorless globules, less in size than
the red corpuscles, to which the name of lymph globules is
given ; their real nature is not well understood. Very soon
after the blood is taken from the body, it separates into a
red mass, called the cruor or clot, and a yellowish liquid, the
§erum. This change is due to the separation from the
liquid of a portion of fibrin, which involves, as in a net, the
blood corpuscles, and forms a soft mass distended with
serum. If the blood, as soon as drawn, is stirred with a
branched stick, the fibrin which separates, adheres in the
form of white silky filaments, and the coagulation of the
blood is prevented. The same
result is obtained if the recent
blood is mixed with three or
four volumes of a saturated
solution of sulphate of soda;
this holds the fibrin in solu-
tion, and the red corpuscles
^BSb mmiS separate unaltered; they may
^Pr f^j W&? ^e seParateQj D J a ^nen filter,
and washed from the serum
with a solution of sulphate of
soda, provided a current of air
is kept up through the mix-
Fig. 421.
tore. These bodies in the blood of most mammiferous ani*
Digitized by VjOOQ 1C
BLOOD. 519
amis are red circular discs, with a depressed centre and color
less exterior; those of birds, reptiles, and fishes are elliptical.
Figure 421 shows the blood discs of the common frog,
as they appear under the microscope. The corpuscles
in man are very small, being not more than from 33*33 to
j (fo?y of an inch in diameter; those of frogs are three or
four times greater in their longer diameter. Figure 422 is
a microscopic view of the red
globules in the blood of man; Q.i
they are very similar to those
of other mammals; the cen- *
tral portions are less brilliant *^
than the borders. The discs A j
are often seen resting upon J
each other flatwise, as they *k3f w SSy^jP^ fj*
are represented at a a a, and |}Sf aJc
more frequently edgewise, as %& "*<& rw@
*tbb. ^ CBBa
897. When placed in pure £9
water, the corpuscles swell,
burst, and dissolve into a deep Fig' 422#
red liquid, which is coagulated by heat, and contains a large
portion of protein, analogous to albumin. The coloring mat-
ter is separated from this by ammoniacal alcohol, in which it
ilone is soluble, and is obtained by evaporation as a dark red-
brown mass, which is insoluble in pure water, but dissolves
with the aid of alkalies, forming a blood-red solution. It
constitutes but four or five-hundredths of the dried blood-
globules, and is called hematosine. It contains a large
portion of iron ; chlorine separates the iron and renders the
matter colorless; an alkaline sulphuret or sulphuretted
hydrogen renders it greenish-black, probably from the sepa-
ration of a metallic sulphuret, and strong sulphuric acid is
said to remove the iron, forming a protosalt, and leaving the
red color unaltered. The condition of the iron is analogous
to that of this metal in some salts, as in the tartrates, in which
it is not precipitated by the ordinary reagents. The coloring
matter, according to Mulder, affords by analysis,
Carbon 66-49
Hydrogen 5*30
Nitrogen 10-50
Oxygen 1105
Iron •• 6*66
10000
Digitized
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620
OBGANIO CHEMISTRY.
898. The serum of the blood is alkaline, and ' j *cains a
large amount of dissolved albumen, which is coagulated by
heat; besides this, it holds in solution a considerable amount
of salts, which are chlorid of sodium, with sulphates, phos-
phates, and carbonates of potash and soda, phosphates of
limo and magnesia, and peroxyd of iron. The blood con-
tains besides about 1-6 parts in 1000 of fatty substances,
consisting in part of ordinary saponifiable fats, and in part
of a peculiar fatty acid containing phosphorus, besides
cholesterine, and a fat named seroline. The following table
is by Becquerel and Kodier, and represents the average
composition of healthy human blood of both sexes :
Man.
Woman.
Density of the defibrinated blood
1-0602
1-0280
1-0575
1-0275
Density of the serum
Water........ ......»ii.i.»i,xi. ....* „u
770-000
141-100
69-400
2-200
6-800
791-100
127-200
70-500
2-200
7-400
Red globules
Albumin
Fibrin
Extractive matters )
Salts )
Total amount of fatty matters
1-600
•020
•488
•088
1-004
1-620
•020
•464
•090
1-046
Seroline
Phosphuretted fatty matter
Cholesterine
Saponifiable fat
Chlorid of sodium
3-100
2-500
•334
•566
3-900
2-900
•354
•541
Other soluble salts
Insoluble phosphates
Oxyd of iron
The existence of alkaline carbonates in the blood, has
been denied by some chemists, who assert that its alkalinity
is due to the presence of tribasic phosphate of soda. Traces
of fluorid of calcium, oxyds of manganese, lead, and copper
have been detected in the blood of different animals, and
silica in that of fowls. Besides these, urea and hippurio
acid are found, and uric acid is said to have been detected ;
in certain cases of disease, the coloring matter of the bile,
and its fatty acids, with an increased quantity of cholesterine
appear in the blood. After the ingestion of vegetable food,
the blood also contains a portion of sugar.
Digitized
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BLOOD. 521
899. The color of Arterial blood is bright scarlet, and thai
of the venous blood is dark red. The blood of the veins
acquires the bright red tint in the lungs, and loses it again
in the capillary vessels. These variations in color depend
upon changes in the form and condition of the blood cor-
puscles, producing a difference in the reflection of light;
those in arterial blood being convex and transparent, while
those in the veins have become flattened and semi-opaque.
These changes depend upon the action of oxygen ; this gas
is much more readily and more copiously absorbed by the
blood than by water ; the arterial blood of a horse contains
in a state of solution from J to T\y its volume of gas, which
contains about four parts of oxygen to one of nitrogen; this
oxygen disappears in the capillary vessels, and is replaced
in the venous blood, by carbonic acid gas. When venous
blood is agitated in contact with atmospheric air or with
oxygen, it absorbs this gas, and acquires the bright red
color of arterial blood; on the contrary, the corpuscles
separated from arterial blood and washed with a solution
of sulphate of soda, assume the dark red color of venous
blood and become disintegrated, dissolving and passing
through the filter, unless supplied with oxygen. If, how-
ever, a current of atmospheric air is passed through the
mixture upon the filter, the corpuscles preserve their scarlet
tint, and remain entire.
900. The globules of the blood appear to be living organ-
isms, which are capable of resisting the dissolving action of
a solution of sulphate of soda, so long as life remains, but
almost immediately become asphyxiated when deprived of
air, and at once lose their bright color, and yield to the dis-
solving action of the saline solution. The solutions of some
salts, as sal-ammoniac and the chlorid of potassium, prevent
the aeration of the blood, even in oxygen gas.
The vitality of the blood, a doctrine as ancient as the
time of Moses, is thus sustained by these facts. The sponta-
neous coagulation of the blood, when removed from the
body, or in the veins after death, is caused by the separa-
tion in an insoluble organized form of a portion of dissolved
protein, and seems, like the organization of effused lymph,
to be dependent upon an inherent vitality of the fluid, exte-
rior to, and perhaps independent of the blood corpuscles.
The proportion of fibrin which thus separates is intimately
connected with the state of the vital powers, and affords an
Digitized
byGoogk
522 ORGANIC CHXMI8TRY.
index to the state of the system in health or disease. In
scrofula and other maladies connected with an asthenic con-
dition of the system, the blood coagulates but feebly, and
the amount of fibrin which separates is much less than
ordinary ; while in inflammatory diseases, where the action
of the system is unduly heightened, the blood coagulates
firmly and rapidly, and the proportion of fibrin formed is
much greater than in healthy blood : fibrin constitutes tho
•o-called huffy coat of the blood in inflammatory diseases.
The normal quantity of fibrin in healthy blood may be
stated at from 2-2 to 2*5 parts in 1000 ; while in cases of
phlegmasia it rises to 6 and 7, and in scrofula and the
latter stages of typhus is not above 1*2 or 2. In cases of
death by lightning, and by certain poisons, or from a blow
upon the stomach, or even from sudden mental emotions,
like violent anger, the blood is found to have lost the power
of coagulation. The brood corpuscles are found to diminish
with the proportion of fibrin, and in some cases of scrofula
amount to no more than 64 to 70 parts in 1000; they are at
the same time, small, pale, and irregular in shape. The pro-
portion of globules is also diminished after blood-letting or
hemorrhages, and while in acute diseases generally, it remains
unaltered, is increased in plethoric patients. The propor-
tion of albumin and fibrin taken together , generally remains
unchanged, except in what is called Bright' s disease, when
the amount of albumin is notably diminished, a change de-
pendent upon its excretion in the urine. The mean com-
position of the blood in the two sexes is seen, by the table
already given, to be somewhat different, (§ 898.)
901. The Fledh Fluid.— The recent muscular fibre from
which the blood has been drained, contains about 80 per cent,
of watery fluid, which may be removed by chopping the flesh
and washing it with cold water. The liquid thus obtained, un-
like the blood, has an acid reaotion ; when heated, a form of pro-
tein resembling albumin coagulates; if the acid liquid is then
neutralized by baryta-water, phosphate of baryta and phos-
phate of magnesia separate, and by evaporation, sparingly
soluble, colorless crystals of creatin CgH9N,04, are deposit-
ed. This substance is neutral, but when its solution is
evaporated with an acid, it loses HfiOfl and is converted
into a crystalline, strongly alkaline, organic base, creatinine
C.H7N809, which under certain circumstances unites with
HjO,, and regenerates creatin* When boiled with an excess
Digitized
byGoogk
THE FLESH-FLUID. 523
of caustic baryta, creatin is decomposed, ammonia is evolved,
and a carbonate formed, from the decomposition of urea;
the liquid affords crystals of sarcosine C6H-N04. Creatin
with water yields urea and sarcosine, C8H9N804+Hi09 =
CsH4NflOs+C6H7N04. Sarcosine is metameric with alanine,
which it very much resembles in its general characters,
and is like it an organic base, but is distinguished from
alanine and its homologues, by subliming unchanged at a heat
of 212° F. There are evidently two metameric series of
bases of the type CwHn4.1N04, which are represented by
alanine and sarcosine; glycocine and leucine appear to pertain
to the same series as alanine, while the sulphuretted base
thialdine, CiaH18NS4 would seem from its ready volatility
to belong to the series of sarcosine.
902. The flesh-fluid also affords a peculiar acid, called ino-
sinic acid, which is very soluble in water, and has the peculiar
flavor of broth. Its probable formula is C^H^N^^, repre-
senting a bibasic acid. The salts of inosinic acid crystallise
beautifully ; that of baryta is sparingly soluble ; and those of
potash and soda evolve, when decomposed by heat, a strong
and agreeable odor of roasted meat. Besides this, an acid,
which appears to be a modification of lactic acid, is obtained
from the flesh-fluid. Creatin has been found alike in the
flesh of birds, beasts, reptiles, and fishes. Fowls, which con-
tain the largest quantity, furnish about T^u of creatin, and
about half as much of the inosinate of baryta. Creatin and
creatinine are also found in the urine, and uric acid has
been detected in the muscle of an alligator.
The flesh-fluid contains a considerable amount of salts,
principally alkaline phosphates and chlorids ; the salts of
potassium here predominate, while those of sodium are more
abundant in the blood.
903. Saliva. — This fluid in its normal state is slightly
alkaline, and contains, besides animal matter, small por-
tions of salts, principally chlorids and phosphates of alka-
line bases ; in that of man a small portion of a soluble
sulphocyanate is found.
The pancreatic juice is also alkaline, and analogous to the
saliva in its composition ; both of these secretions contain in
solution an azotized organic substance, which may be preci-
pitated by alcohol, and like diastase possesses the power of
rapidly transforming a solution of starch into dextrine and
glucose. They are supposed in this manner to exercise an
Digitized by VjOOQlC
624 ORGANIC CHEMISTRY.
important part in preparing these substances for assimila*
tion. The serum of the blood has a similar action upon
starch.
904. The secretion of the stomach, called the gastric juice^
is acid in its reaction, and contains portions of alkaline chlo-
rids, free lactic acid, and an azotized substance similar to
that of the saliva. It has the power of dissolving, at the
temperature of the body, fibrin, coagulated albumin, and
other forms of protein, but has no solvent action upon starch ;
if however the gastric fluid is rendered feebly alkaline, it no
longer dissolves protein, but acts upon starch like the saliva
and pancreatic juice. In the same way these, when rendered
acid, acquire the power of dissolving protein. The tissue of
the pancreas from a dead animal, when out in pieces and
mixed with water, still exerts a solvent power upon starch,
and the lining membrane of the stomach, when digested
with water slightly acidulated with chlorohydric acid, forms
an artificial gastric juice. The animal matter of the gastric
juice, which is apparently identical with that of the saliva,
has been named pepsin, (from pepto, I digest,) and like
diastase is at once rendered inactive by a boiling heat, and
by various antiseptics. It is analogous to the protein bodies
in its composition, and like them has, under certain condi-
tions, the power of converting sugar into lactic acid, and
thus changing its reaction, so as to become capable of dis-
solving protein.
905. The bile has already been shown (879) to consist essen-
tially of the soda-salts of two azotized acids : besides these,
there are small portions of alkaline chlorids and phosphates,
and some mucus, the azotized secretion of the mucous
surfaces. The substance of the liver generally contains a
small portion of sugar. The bile is alkaline in its reactions,
and has the power of rendering fats and oils soluble,. acting
like a soap, and apparently fitting them for the process of
assimilation. The same power is possessed by the saliva and
pancreatic juice, which with the bile and gastric juice are
brought in contact with the food in different parts of the
alimentary canal, and by their combined action render the
amylaceous, fatty, and proteinaceous portions of the food
soluble, and ready to be elaborated in the form of chyle.
Such, in the present state of our knowledge, seems to be the
nature and result of the process of digestion.
Digitized
byGoogk
CHYLE. — URINE. 52S
$06. Chyle. — This fluid in the human body, as taken
up by the lacteals from the small intestines, is white and
opake, and contains dissolved protein in a form resembling
albumen, with small globules of fat, to which its milkiness
is due, and a portion of sugar, besides various salts and a
portion of iron in a soluble form ; when first taken up from
the intestines, it yields but very little fibrin, but the chyle
from the thoracic duct coagulates like blood, yielding a clot
which contains fibrin, and the clear liquid resembles the
serum of the blood, to which this liquid is already as it
were in a state of transformation, wanting only the red
corpuscles.
The solid excrements of animals contain portions of the
food, insoluble or unfit for assimilation ; those of the herbi-
vora are made up in part of ligneous matter, and those of
carnivora contain a portion of an azotized substance, and yield
ammonia by their decomposition ; phosphates and other salts
are present in considerable quantity, in the excrements, and
render these substances valuable as manures.
907. Urine. — This excrementitious substance is separated
from the blood by the kidneys, and removes from the body
various salts and azotized matters. The latter are urea
and hippuric and uric acids, which have already been
described. The urine of birds and reptiles, which is white
and solid, is principally urate of ammonia. That of herbi-
vorous mammals is alkaline, and contains in solution, besides
urea, a large amount of hippuric acid ; while in carnivora
this acid is wanting, and a large amount of urea is found,
with a little uric acid. This is nearly the composition of
the urine of man subsisting upon a mixed diet : the average
quantity of urea in healthy human urine is about 3 per
cent., and that of uric acid about T^cu ; it also contains a
little hippuric acid. When benzoic acid is taken into the
stomach, the urine a few hours afterward is found to con-
tain a large amount of hippuric acid, apparently formed in
some way from the benzoic acid. Creatin and creatinine
are also found in urine, and that of young salves contains
in addition to a considerable quantity of creatinine, a notable
amount of allantoin. The saline matters of the urine general-
ly amount to two or three per cent., and consist of chlorid of
jodium, with sulphates and phosphates of potash and soda,
And traces of ammoniacai salts, besides phosphates of lime and
Digitized
byGoogk
, 626 OBQAMIO CHEMISTRY.
magnesia. Urine also contains a peculiar organic coloring
matter, and a portion of mucus from the bladder, which in a
few hours excites a decomposition of the urea, the liquid
becoming alkaline from the carbonate of ammonia formed.
If this mucus be removed by nitration, the urine may be
preserved a long time without change. When putrescent
urine is evaporated, the ammoniacal salt forms with the
phosphate of soda, the doable phosphate of soda and ammo*
nia, which was formerly known as the essential salt of urine,
or microcosmic salt.* If the residue is evaporated to dryness
and distilled at a red heat, the acid of a portion of phos-
phate of ammonia is decomposed by the organic matter
present, and a small quantity of phosphorus is obtained;
it was by this process that this curious element was first
prepared.
The fresh urine of man and the carnivora has an acid re-
action, which is ascribed to the uric acid held in solution
by phosphate of soda : on adding a little chlorohydric
acid to the urine, the uric acid separates after a few hours
in small but distinct crystals.
908. In disease the composition of this fluid is sometimes
altered, and the elements of the chyle and blood find their
way into the urine : in some forms of dropsy and diseases
of the kidneys, it contains albumin, while the urea is
deficient, and is found in the blood and other fluids of the
body. In other cases, all the sugar contained in the food,
or formed in the digestive process from starch, is excreted
in the urine, under the form of glucose, and constitutes
the disease called diabetes mellitus : in this disease the urine
still contains urea in large quantity.
In some states of the system, the uric acid increasing in
quantity, or the solvent power of urine being diminished,
this acid is deposited in the form of gravel or calculus. Urio
acid or urate of ammonia constitutes the most common form
of calculus ; but phosphate of- lime, and the phosphate of
magnesia and ammonia, besides oxalate and more rarely
carbonate of lime, are also found as urinaiy concretions.
* So named by the older chemists as it was then supposed to be a
•alt peculiar to man, Man was called the microcosm, because in hit
three-fold nature is repeated in miniature the order of the universe, the
great konmo* or macrocosm.
Digitized
byGoogk
MILK. 527
909. Milk.— This secretion ^cgtST^^
of the female contains in a s^£$^jJs^$& % *
soluble form all the substances ^wl£85?? <& 5%^
necessary for the nutrition of A#*^%&| d & r^gSk
the young, — protein, fat, su- if^SS aM^* *ol?§&
gar, and various salts. When K^^^% ^ ?v*5
viewed under the microscope, ^^fe^S^ j>i * jF °^
milk is seen (fig. 423) to con- |3||S^Eft 3^ tJ^^SX, qa
tain numerous globules of fat v*£& g o^ ^?o °a|S7
suspended in a clear liquid ; Qr^Sr>^^ dT
these globules are butter, and tS&jS* o j% *"
give to milk its opacity. The ^** * o0 ^ ^
proportions of its ingredients F. 423
vary, but the following analy- **'
sis of oow's milk may be taken as an example : — 1000 parti
contain,
Water.. 8730
Butter. 30-0
Casein, and a little albumin 48*2
Milk-sugar, or lactose 43.9
Phosphate of lime, with a little fluorid of calcium 2-3
Chlorids of potassium and sodium 1*7
Phosphate of iron and magnesia, with a little soda com-
bined with casein *9
1000-0
Woman's milk contains proportionably more sugar and
less casein, and in these respects it resembles asses milk,
which also contains but little butter : the milk of carnivore
likewise contains a considerable proportion of sugar, even when
the animals have been fed for a long time exclusively on flesh.
It is in this case probably derived from the transformation
of gelatin or protein, in the manner already pointed out;
and the lactic acid in the flesh-fluid of carnivora must havo
a similar origin.
910. When milk is saturated with common salt and filtered,
a clear liquid is obtained, which holds in solution the casein,
sugar, and salts; while the butter rests upon the filter in the
form of globules, which are enclosed in an albuminous mem-
brane, and are insoluble in ether. If, however, the milk is
first boiled, the albuminous coating appears to be dissolved,
and the whole of the butter is dissolved by agitation with
ether, leaving the milk transparent. After a few hours' repose
the greater part of the globules rise to the surface in the form
of cream. In describing casein, (875,) the effect of acids in
Digitized
byGoogk
MS ORGANIC CHEMISTRY.
producing the coagulation of milk has been already noticed :
the whey contains all the sugar, and the soluble salts. Tlie
spontaneous coagulation of milk depends upon the forma-
tion of a little lactic acid from the sugar : in the prepara-
tion of cheese, an infusion of the lining membrane of
a calf s stomach, called rennet, is added, which causes an
almost immediate separation of the casein in an insoluble
form ; this reaction does not depend upon the formation of
lactic acid, but may take place in the presence of an excess
of alkali ; milk in its recent state has an alkaline reaction.
In cheese which has been long kept, there are found seve-
ral products of the decomposition of casein, among which
are salts of butyric and valeric acids, and probably leucine ;
besides butter from the milk, cheese often contains a
portion of fat, from the transformation of the casein already
described.
911. Egg$. — The white part of the eggs of fowls con-
sists of a solution of albumin, with small quantities of
soda and various salts : on boiling eggs, a portion of sul-
phur, from the albumin, combines witn soda to form a sul-
phuret of sodium, which is recoguized by the blackening of
a piece of bright silver. The yolk of eggs contains, besides
a protein compound, a large portion of oil which consists
principally of oleine and margarine, and a peculiar viscous
matter which contains ammonia, and yields, by the action of
acids, oleic and margaric acids, and a soluble acid which
appears to contain the elements of phosphoric acid and
glycerine. Besides these, lactic acid and the salts which are
found in the blood and flesh-fluid, are present.
912. The brain and nervous substance are similar in their
chemical nature, and the white and gray portions of the
brain differ chiefly in their structure ; they contain about
80 per cent, of water. The solid matter consists in part
of a protein body, and in part of a substance which, by
the action of acids, yields products similar to the viscous
matter of the yolk of eggs. Besides these there is present
% fatty orystalline acid, which contains nitrogen and about
one per cent, of phosphorus, and has been named cerebric
xcid. It is but little known, but is probably somewhat
analogous to the acids of the bile. It appears to be identi-
cal with the phosphuretted fat of the blood ; cholestexine
is also present in the substance of the brain besides an
Digitized
byGoogk
BONES. 529
oily fat acid , which appears to contain the elements of phos-
phoric and oleic acids. The solid matter of the brain con*
tains about four per cent, of phosphorus.
913. Bones, — The bones consist of a tissue of insoluble
gelatine enveloping a large amount of earthy salts. The
bones of young animals contain but a small portion of mine-
ral matter, which increases with their growth. A deficiency
of the solid ingredients occurs in rickets, and other diseases
connected with defective nutrition. The dried bones of
adults contain from 30 to 40 per cent, of organic matter,
which is almost entirely soluble in boiling water ; water also
removes small quantities of salts of soda. The remainder,
is principally tribasic phosphate of lime P05.3CaO, with
small portions of phosphate of magnesia, carbonate of lime,
and fluorid of calcium. The two analyses which follow are
of a human femur and the femur of an ox : —
Man. Ox.
Phosphate of lime 58*30 59*67
Phosphate of magnesia.....: 2*09 1-21
Carbonate of lime 7*07 6*39
Fluorid of calcium 2*73 2*05
Organio matter 30*58 31*11
100-77 100-43
When a bone is immersed in a dilute acid, as the chloro-
hydric, the earth^ salts are entirely removed, and the bone
becomes translucent and flexible. It then dissolves in boil-
ing water, leaving only a small portion of insoluble tissue,
consisting of the blood-vessels which penetrated its sub-
stance, and which are composed of protein. The horns of
the deer are analogous to bones in composition ; the tusks of
the elephant, which constitute ivory, and the teeth, are very
similar : the latter contain less organic matter than bones,
and in the enamel of the teeth, which contains a considera-
ble amount of fluorid of calcium, the animal matter is
absent.
914. The horns of cattle, which, unlike those of the deer,
are flexible and softened by heat, are, like the hoofs of ani-
mals, composed of a protein body containing a large amount
of sulphur. The skeletons of zoophytes and the shells of
mollusks contain a small quantity of animal matter, with
carbonate of lime and small portions of phosphates of lime
and magnesia and fluorid of calcium. Those of many
crustaceans consist principally of phosphate of lime with
a little magnesia and carbonate of lime.
Digitized
byGoogk
680 ORGANIC 0H1MI8TRY.
When the leather-like coating of the satpm and some othef
tunicate mollusks is digested with a solution of potash, the
nervous and muscular portions are dissolved, and the in-
soluble residue contains no nitrogen, and appears identical
in composition to the cellulose of plants.
NUTRITION OF PLANTS AND OF ANIMALS.
915. In the order of nature, the animal creation derives
its support from the vegetable, whose products are directly
or indirectly the food of the former. A large number of
animals subsist upon herbs or grains, and the flesh of these
vegetable feeders is the food of carnivorous animals. Plants
have the power of forming from carbonic acid, water, and
ammonia, those bodies of tne carbon series which are neces-
sary for the support of animals. The nutrition of plants
may then be properly considered first in order.
916. The organic substances essential to plants are cellu-
lose and protein, to which we may perhaps add starch;
these go to make up the simplest vegetable structure, and
neither of them are probably ever wanting. In addition to
these are sugar, gum, oils, resins, acids, alkaloids, and
many other substances, some one or more of which are gene-
rally present in different parts of plants. The history of
the related series of cellulose, starch, sugar, and gum, and
of the protein compounds, has been already given. These
bodies in their organized forms always contain small and
variable portions of salts of potash, soda, lime, and magnesia,
with chlorine, phosphoric, sulphurio, and silicic acids. The
juices of plants contain these same salts in solution, some-
times with the addition of those of ammonia, and various
vegetable acids, either free or in the form of salts. These
mineral ingredients appear essential to healthy development;
they perform, however, but a secondary part in the nutrition
of plants, whose food consists essentially of water, carbonic
acid, and ammonia, from which, as has been already said,
they form the various organic substances, by the combina-
tion of certain molecules and the elimination of certain
others, in a manner similar to that which we have so often
illustrated in the preceding pagos.
Digitized
byGdogk
NUTRITION OF PLANTS AND ANIMALS. 531
917. Cellulose and the allied substances contain pre-
siBely the elements of carbon and water, and may be formed
from the elements of carbonic acid gas and water, cr rather
from hydrated carbonic acid C9HfiOfl, by the separation of
oxygen; ^CJff^O^C^HaoO^+O^. Protein, which we
have shown may be regarded as the amid of cellulose, iff
formed with the concurrence of the elements of ammonia,
in a manner which will be at once understood. Sugar and
gum differ from cellulose only by the elements of water,
and the various vegetable acids and other matters contain-
ing oxygen, hydrogen, and carbon, may be formed in a
manner analogous to cellulose from carbonic acid and water,
by the separation of oxygen. It is probable that the saline
and alkaline matters in the juices exercise peculiar influences
upon these processes, and conduce to the formation of the
various products.
918. The oxygen set free in all these processes is evolved
in the form of gas. If a branch of a green healthy plant is
exposed, under an inverted bell-glass filled with water, to
the sun's rays, minute bubbles of gas appear upon the leaves,
and rise to the top of the vessel. They are pure oxygen,
which is constantly evolved by all healthy plants when
exposed to the influence of light. In darkness, the action
is suspended or imperfectly performed, and the carbonic acid
which is absorbed by the roots, is given off from the leaves
instead of oxygen ; the leaves of plants also exhale large
quantities of water. Although it is principally through
the roots that carbonic acid, water, afld ammonia are taken
up, the leaves have also the power of absorbing water and
gases for the support of the plant.
If a plant is made to grow in a mixture of oxygen and
carbonic acid gases, the latter is gradually absorbed and
replaced by pure oxygen. Flowers and fruits, during the
period of their growth, however, reverse this process, and
absorb oxygen from the atmosphere, while they evolve car-
bonic acid gas.
919. The atmospheric waters falling upon the earth, con-
tain in solution a portion of carbonic acid and a minute
quantity of carbonate of ammonia, two ingredients which
are always present in the atmosphere. The water dissolves
from the soil a minute portion of earthy and alkaline salts,
which are in part set free by the disintegration of the earthy
minerals under the influence of water and carbonic acid
Digitized
byGoogk
632 ORGANIC CHEMISTRY.
In this form the different elements are taken up by tho
rootlets of the plant, and while the carbonic acid and am-
monia are assimilated in the way that we have seen, tho
sulphates and phosphates furnish the portions of sulphur
and phosphorus contained in vegetable protein, while their
alkaline bases with the vegetable acids, form salts, which,
being decomposed by heat, are the source of the alkaline
carbonates, always found in the ashes of vegetables. The
bitartrate of potash in the juice of grapes is an example
of the occurrence of an organic potash salt.
920. Careful analyses of their ashes have shown that the
nature and proportions of saline matters differ greatly in
different plants, and that the long-continued cultivation of
any species of plant upon the same soil may so far exhaust
the soluble mineral matter as to render the soil unfruitful.
In such circumstances, its fertility may be restored by the
application of mineral manures, such as bone-dust, gypsum,
and wood-ashes. A soil which has become unfitted for the
growth of one plant may still contain the mineral substances
necessary for the support of another, and hence the utility
of an alternation of crops in agriculture. The ashes of
tobacco contain, for example, a large amount of potash salts,
and those of wheat and other cereal grains abound in phos-
phate of lime, and contain but little potash ; so that a soil
unfitted for tobacco may still produce good wheat, and vice
versa. Many plants which grow in the vicinity of the sea
contain a large amount of salts of soda ; such are those that
afford the impure alkali kelp or barilla. The amount of
mineral matter in many of the fucoids or sea-weeds is very
large, and the quantity of potash which they contain some-
times exceeds that of the soda ; a fact which shows the curious
power of plants to choose certain elements in preference to
others, for the proportion of potash salts in sea-water is very
small. The ashes of marine plants are also remarkable for
containing salts of iodine, an element which cannot be
detected in sea-water, but is contained in considerable quan-
tity in the plants growing therein, and is even present in
traces in many fresh-water plants.
921. Fertile soils generally contain a portion of organic
matter, derived from the decomposition of roots, leaves, and
other vegetable substances, and approaching to what has
been named humus or humic acid. This substance by its
slow decomposition constantly evolves carbonic acid, and is
Digitized by VjOOQ IC
NUTRITION OF PLANTS AND ANIMALS. 533
thus a source of carbon to the roots of plants. This organic
matter also contains in its substance the various salts neces-
sary for plants, and during its decay, sets them free in a
soluble form. It is still further efficient by the power which
it possesses, in common with charcoal, clay, and other porous
substances, of absorbing the ammonia contained in the air or
evolved from the decomposition of azotized matters, and
holding it in such a form that it is dissolved out by atmo-
spheric waters, and brought to the roots of plants. It would
also appear, from the experiments of Mulder, that humus
possesses the power of forming ammonia with the nitrogen
of the air.
. 922. Some chemists maintain that soluble forms of humus
are directly absorbed by the roots, and thus constitute their
food : there are however no proofs of such an absorption, and
many arguments against it. It is well established that, if
supplied with atmospheric waters and the proper mineral
ingredients, plants will flourish and mature their seeds in
a soil destitute of organic matter. Many plants are para-
sitic, and grow without any connection with the soil ; they
may be suspended in the air, and will continue to grow for
years, absorbing food through their leaves, and generating
cellulose, protein, and other organic bodies. The small
portion of mineral matter which these plants contain, may
be derived from the solution and absorption of the dust
floating in the air.
In the process of germination, the albumin of the moisten-
ed seed becomes soluble, and its starch is converted .into
sugar : these substances serve to nourish the embryo plants,
but when the roots and leaves are fully formed, the plant
begins a new mode of life. Its carbon is derived from
carbonic acid, and the decomposing organic matters of the
soil serve only as sources of carbonic acid, ammonia, and
salts. We have seen how some of the fungi excite the
decomposition of protein and sugar solutions, apparently
assimilating a portion of the evolved carbonic acid and ammo-
nia, and it is not improbable that the rootlets of the higher
orders of plants may act in a like manner upon the organic
matters in the soil, thus accelerating their decomposition.
923. Animal matters act beneficially as manures, by the
ammonia which they evolve with the carbonic acid, in the pro-
cess of decay. Bone-dust in addition, affords phosphates;
and urine, besides its ammonia, contains a great variety of
Digitized
byGoogk
534 ORGANIC CHEMISTRY.
*arthy and alkaline phosphates, and ohlorids. Dilate solu-
tions of sulphate, or other salts of ammonia, act as powerful
stimulants to vegetation, and the efficacy of guano, which is
the decomposing excrement of sea-birds, is due in great part
lo the ammonia which it yields. In its recent state it con*
tains besides inorganic salts a large portion of urate of
ammonia, from which, during decomposition, oxalate and
other salts of ammonia are formed. Wheat manured with
guano is said to contain a larger proportion of protein than
that grown upon the same soil without the manure. The
efficacy of gypsum depends in part upon its furnishing lime
and sulphates to plants, and in part apparently from its
power of condensing and retaining in the form of sulphate,
the ammonia from the air and other sources. The ammo-
nia contained as carbonato in atmospheric waters being
brought in contact with earthy salts in the soil, must always
be brought to the roots of the plants, in the form of sulphate
or chlorid, or as a soluble ammonia-magnesian salt.
924. The food of animals, whether they feed upon flesh,
or upon vegetable substances, consists of protein in its vari-
ous forms, starch, sugar, gum, and fat, to which, in the case
of carnivorous animals, gelatine is to be added. The vege-
table feeders convert the protein bodies of their food into
muscular fibre, which is afterward the food of the carnivora.
These protein compounds, which can alone form blood and
muscle, are to be distinguished from the non-azotized por-
tions of the food, and have been called the plastic elements
of nutrition, in distinction from the'latter, which are named
the plastic elements of respiration, being consumed in that
Erocess. Gelatine probably belongs to the latter class ; it
as never been found in the blood, and is supposed to be
converted into sugar and ammoniacal salts.
925. The power of producing from simpler bodies, the
complex organic products, does not belong to the animal
system. The process of digestion has already been briefly
described ; the saliva, bile, gastric and pancreatic juices exert
upon the food an essentially disorganizing, destroying action,
which reduces it to a soluble plastic form, fit for assimila-
tion, in which process the protein assumes an organic struc-
ture, and forms blood and muscular fibre, while gelatine is
probably formed from a portion of it, by a reaction not well
understood. The sugar contained in the food or formed
fronj the starch, appears to be in great part absorbed by
Digitized
byGoogk
NUTRITION OP PLANTS AND ANIMALS. 535
the coats of the stomach and small intestines, in the same
way as water and saline fluids, and thus finds its way into
tne veins, without passing through the chyle-duct. It is
directly oxydized in the circulation, and in a few hours
after its ingestion disappears entirely from the blood. Alco-
hol is absorbed in the same way, and oxydized in the circu-
lation, being converted into water and carbonic acid, ^.ce-
tio acid has been found in the blood as an intermediate
product of the oxydation of alcohol, and formic acid is said
to have been detected after the ingestion of sugar.
The fat, which, with the protein, passes through the chyle
into the blood, is deposited in the adipose tissues : besides
that contained in the food, it is probable that fat is formed
by some process from the other aliments; its spontaneous
production from protein has been already described, and we
have seen how fatty acids, like the butyric, valeric, and
capric, may be formed from sugar, and by the oxydation of
protein. To these considerations may be added some ex-
periments which seem to show that geese, in the process of
fattening, secrete a greater amount of fat than is contained
in the food which they consume.
926. It has been shown that the blood in the lungs dis-
solves a large portion of oxygen gas. The cells of that
organ are filled with air in the process of respiration, and
the minute branches of the pulmonic artery are spread over
the walls of the cells. The delicate arterial membrane being
permeable to gases, oxygen is absorbed and carbonic acid
gas given off through it. The use of the oxygen in the
oxydation of sugar and alcohol has already been shown;
the whole of the oxygen absorbed, is not given out in the
form of carbonic gas, but is in part exhaled as aqueous
vapor from the lungs, and from the skin.
There is, in addition to this oxydizing process, a constant
action going on in the tissues, which results in their disor-
ganization and conversion into simpler forms. This is
effected in the capillary vessels with the concurrence of the
dissolved oxygen of the arterial blood; protein is decomposed,
with the addition of oxygen, into a set of highly carbonized
bodies, the fatty acids of the bile ; and of highly azotized sub-
stances, urea and uric acid, which are carried by the veins
to the liver and kidneys, and are separated from the blood;
in the one case to be voided in the urine, and in the other
to be returned to the alimentary canal, ai*d there to perform
Digitized
byGoogk
536 ORGANIC OHSMI8TBT.
some part in the nutritive process. It is not improbable
that the acids of the bile may be converted into ordinary
fats, which are thus indirectly formed from the protein
tissues. Lactic acid on the one hand, and creatin and in*
osinic acid on the other, are also products of this metamor-
phosis, which has been called the destructive assimilation.
Its relation to the matter of the brain and nerves is not yet
well understood.
927. The oxydation of fat, by which it is converted ulti-
mately into carbonic acid and water, does not probably take
place in the circulation, as in the case of sugar, but is effected
through the capillary vessels, in the tissues where the fat
has previously been deposited. When the amount of sugar,
and farinaceous food is great, animals grow fat, for the glu-
cose preserves the fatty tissues from the influence of the
oxygen, whicji is consumed in the oxydation of the sugar
and the change of the protein tissues. If, however, the
supply of farinaceous food is diminished, the fat is removed
by oxydation faster than it is deposited, and finally dis-
appears.
928. The object of nutrition, in its wider sense, is to
supply the waste of the tissues, and satisfy the demands of
the respiratory process, thus preserving the balance of the
system. In those animals that feed upon flesh, the fat con-
tained in their food or formed from protein, supplies the
wants of the latter process; while in those animals which
live upon vegetables, or like man upon a mixed diet, the
sugar, alcohol, and farinaceous portions of the food supply
more or less completely the demands of the respiratory
process, and, if these be in excess, the fat contained in the
food often accumulates in the system.
The waste of the muscular, and probably also of the
nervous substances, appears to sustain an intimate relation to
the amount of muscular and nervous activity of the system,*
while the oxydation of the respiratory elements is related to
animal heat Respiration is essential to life, and even in
those animals which do not breathe air, the process is ef-
fected through oxygen dissolved in the water. We have
* The condition of sleep, in which the muscular and nervous energies
are to a great degree suspended, probably sustains an important relation
tc the nutritive process, particularly as related to the brain and nerves.
The different functions of plants in light and darkness suggest an analogy
in this connection, which is worthy of consideration.
Digitized
byGoogk
NUTRITION 0! PLANTS AND ANIMALS. 537
shown thai oxygen is necessary to preserve the life of the
Mood corpuscles out of the body ; and it is the deprivation
of air which causes the death of animals, by preventing the
aeration of the corpuscles, and destroying the vitality of the
blood. The introduction of large quantities of alcohol into
the system produces a similar asphyxia, by rapidly con-
suming the oxygen, and thus preventing the proper aeration
of the blood. The presence of phosphuretted fat, mentioned
in the analyses of the blood before given, is said to be confined
to the venous blood, which contains no soluble phosphates ;
in the arterial blood the fat is freed from phosphorus, which
is found in the form of phosphates in the serum.
929. The oxydation of carbon and hydrogen compounds,
converting them into carbonic acid and water, is supposed
to be the source of vital heat in animals; the amount of
carbon thus thrown off from the lungs of a full-grown man
is equal to about seven ounces in twenty-four hours. In
some instances of disease, however, where the respiratory
function has been suspended for many hours, the heat of
the body has remained undiminished. Plants have equally
to a certain extent, the power of maintaining a temperature
above that of the atmosphere : this is most evident in the
leaves and young shoots, where vegetation is most active;
but in plants the vital process is accompanied with a con-
stant evolution of oxygen, from an action the very reverse
of that which goes on in animals. Heat is a common result
of chemical changes, even where oxygen is not absorbed,
and there is no difficulty in understanding its production in
any of the processes of assimilation.
It is, however, probably true, that in healthy animals the
oxydation of carbon sustains a direct relation to the heat
evolved. Hence it is that in warm climates, where the loss
of animal heat is small, farinaceous matters, containing a
large amount of oxygen, and as it were, partly oxydized,
are the food of the people, and are found most congenial to
the taste ; while the inhabitants of arctic regions consume
large quantities of fat and oil, less oxygenized species of
food, which are found not only agreeable, but necessary to
support the demands of the respiratory process, and to resist
the intense cold.
930. The elements of the food of plants are taken from
the air, earth, and waters, and by the forces of the living
organism are formed into woody fibre, starch, sugar, and
Digitized
byGoogk
688 ORGANIC OHEMI8TRT.
protein, which serve for fuel and for the nourishment of
animals. By the processes of life, by combustion and
decay, these elements are again set free in the forms of
water, carbonic acid, and ammonia, and enter once more
into the current of organio life. In this way, the results
of the decomposition of organio matters are removed from
the atmosphere, whioh would otherwise be vitiated by them,
and the carbonic gas which is taken up by plants, is re-
placed by an equal volume of oxygen gas, so that the purity
of the air is preserved.
In the mutual dependence of the great processes of animal
and vegetable life and decay, there is seen a system in which
no one process is its oyrn end, but is implicated in every
other, and can be understood only in its relation to the
Universe, and to that Being who is at once the efficient and
final Cause of all creation.
Digitized
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APPENDIX,
CONTAINING TABLES OF WEIGHTS AND MEASURES, OF CORRESPOND-
ISO THERMOMETRICAL DEGREES, HYDROMETER TABLES, STRENGTH
OF ALCOHOL, AND ANALYSES OF WATERS.
WEIGHTS AND MEASURES.
AVOIRDUPOIS, OR IMPERIAL WEIGHT.
Equivalent! In
Troj grains.
1 drachm 27*34.
16= 1 ounce. 437-5
256= 16= 1 pound............. 7000-
8584= 224= 14= 1 stone 98000-
28672= 1792= 112= 8= 1 hundred weight... 784000-
478440=85840=2240=160=20=1 ton 15680000*
TROT WEIGHT.
1 grain.
24 " = 1 pennyweight.
480 " =20 " t
5760 « =240 " t
s 1 ounce.
b12 " =1 pound.
APOTHECARIES' WEIGHT.
1 grain, gr.
20 " = 1 scruple, 9
60 « = 8 " = 1 drachm, $.
480 " = 24 " = 8 " =1 ounoe, g.
6760 « =288 " =96" =12 « =1 pound, lb.
589
Digitized
byGoogk
540
APPENDIX.
APOTHIOAJtlH', OR WIH1 M1A8UBI.
Adopted «n the United State* and Dublin Pharmacopceiae.
CaMoiaehat.
1 minim, tiR -00876...
60= 1 fluid-drachm, f 3. -2256 ...
480a 8a 1 fluid-ounce, fg.,.. 1-8047 ...
7680a 128a 16al pint, 0 28-8760 ....
Troj gratM «f
pur« water.
at 000 r.
0-95
m 56-96
. 466.607
a 7289-724
61440wl024a.128a.8oil oong 281-000 ...... —68817-798
The imperial gallon contains of water, at 60° 70,000* grains.
The pint (Jth gallon) 8,760- «
The fluid-ounce f^th of pint) 487-6 "
The pint equals 84-66 cubio inches.
The American standard gallon contains of pure water, at 89-88°,
68-872 Troy grains.
The French Jfct%ramm«al6434* grains, or 2*679 lbs. Troy, of
2-206 lbs. avoirdupoids.
The gramme «x 15-4340 grains.
" decigramme a 1-6484 "
" centigramme a -1548 "
" miligramme a -0154 "
The metre of France a39-37 inches.
" decimetre a 8-937 "
" centimetre a -394 "
" millimetre a -0394 "
TABLB OF TH1 COmniSPOKDIVO DIQRI1S OH THX 80ALI8 OF
fahrbuhiit, eeaumub, akd onmoRADi, on gustos.
Fate.
Haaa.
Coat,
Fate.
Reaanu
Caai.
Fate.
Baaa.
Ont
212
80
100
149
62
65
60
8
10
203
76
95
140
48
60
41
4
6
194
72
90
131
44
65
82
0
0
186
68
85
122
40
50
23
4
6
176
64
80
113
36
45
14
8
10
167
60
75
104
82
40
5
12
15
168
66
70
95
28
85
4
16
20
86
24
80
13
20
25
77
20
25
22
24
80
68
16
20
81
28
85
69
12
15
40
32
40
Digitized
byGoogk
APPENDIX.
541
HYDROMETER TABLES.
COMPARISON OF THB DEGEEE8 Or BAUMB'S HYDROMBTER, WITH TH1
EBAL SPECIFIC GRAVITY.
1
. For Liquid* Heavier than Water.
Def-M*.
Specific
gravity.
Degree*.
Specific
gravity.
Degrees.
Specific
grotty.
Degree*.
Specific
gratify.
0
1-000
20
1-152
40
1-367
60
1-652
1
IV*
21
1-160
41
1-869
61
1-670
2
1018
22
1-169
42
1-881
62
1-689
8
1-020
23
1-178
43
1-395
63
1-708
4
1-027
24
1-188
44
1-407
64
1-727
6
1-034
25
1-197
45
1*420
65
1-747
6
1-041
26
1-206
46
1*434
66
1-767
7
1048
27
1*216
47
1-448
67
1-788
8
1-056
28
1-225
48
1-462
68
1-809
*9
1-068
29
1*285
49
1*476
69
1-881
10
1070
80
1-245
50
1-490
70
1-854
11
1-078
81
1-256
51
1-495
71
1-877
12
1-085
32
1-267
52
1-520
72
1-900
13
1-094
38
1-277
53
1-535
78
1-924
14
1-101
84
1-288
54
1-561
74
1-949
15
1-109
85
1-299
55
1-567
75
1-974
16
1-118
36
1-310
56
1*683
76
2000
17
1-126
87
1-321
57
1-600
18
1-184
88
1-833
58
1-617
19
1-148
39
1-845
59
1-634
2
BaunWs Hydrometer for Liquid* Lighter than Water.
Degree*.
Specific
gravity.
Degree*.
Specific
gravity.
Degrees.
Specific
gravity.
Degrees.
Specific
gravity.
10
1*000
28
•918
86
•849
49
•789
11
•998
24
•913
37
•844
50
•786
12
•986
25
•907
88
•839
61
•781
18
•980
26
•901
39
•834
62
•777
14
•973
27
•896
40
•830
53
•778
16
•967
28
•890
41
•825
64
•768
16
•960
29
•886
42
-820
65
•764
17
•964
80
•880
43
•816
66
•760
18
•948
81
•874
44
•811
67
•767
19
•942
82
•869
45
•807
68
•768
20
•936
83
•864
46
•802
59
•749
21
•980
34
•869
47
•798
60
•745 ,
22
•924
85
•864
48
•794
Digitized
byGoogk
641
APPENDIX
TABLES OP ANALYSES
Nos. 1 to 6, inclusive, show the ingredients in 1 American standard
and Nos. 9 and
1
(1)
(2)
(8)
W
Ingrtdienti.
Schuylkill
Biw.
Crofcm
Btor.
Chariot
River.
Spot
Fond.
Chlorid of Potassium...
2
Chlorid of Sodium
•1470
•167
•1647
•8969
8
Chlorid of Ammonium.
...
...
...
•••
4
Chlorid of Calcium
...
•872
•0420
•••
6
Chlorid of Magnesium.
•0094
...
...
...
6
Chlorid of Aluminum...
...
•166
•••
...
7
Bromid of Sodium
«••
•••
•••
•••
8
Bromid of Magnesium.
•••
...
•••
•••
9
10
Iodid of Sodium
—
...
...
•♦•
Sulphate of Potash.....
11
Sulphate of Soda
...
•163
•3*816
•2276
12
Sulphate of Lime
...
•235
•2624
...
13
Sulphate of Magnesia..
•0570
...
•••
...
14
Sulphate of Alumina...
...
•••
...
...
16
Nitrate of Magnesia.. ..
...
...
...
...
16
Phosphate of Lime
...
...
...
andiron.
17
Phosphate of Alumina.
...
•832
•0973
•1081
18
19
20
Alumina
•0800
•077
traces
traces
Silicic Acid
Carbonate of Soda
21
Carbonate of Baryta...
...
...
...
...
22
Carbonate of Strontia..
...
...
...
...
23
Carbonate of Lime
1-8720
2.131
•1610
•8722
24
Carbonate of Magnesia
•3510
•662
•0399
•1420
25
Carbon, of Manganese.
...
traces
...
...
26
Carbonate of Iron
...
...
...
...
27
Fluorid of Calcium
Salts of Soda with the )
...
...
...
...
28
Nitric and Organic !•
Acids J
Total
1-6436
1-866
•5291
—
4-2600
•8879
Author.
6-660
17-418
Author.
1-6680
•0464
Author. |
1-2468
88-79
Carbonic Acid Gas in "1
cubic inches J
Analysed by.. ...t. .......
Author. 1
Note. — No. 1 is the supply for the city of Philadelphia, No. 2
for New York, and No. 5 for Boston ; Nos. 4 and 6 are small lakes
in the vicinity of Boston, and No. 3 is a river in Massachusetts,
emptying near Boston.
Digitized
byGoogk
APPENDIX.
641
OP NATURAL WATERS.
gallon, for 58-372 grains.) Nos. 7, 8, and 9 are in one pound Troy,
10 in ltiOO parts.
(*)
(6)
(7)
(8)
(9)
(10) 1
Long
Mystio
Saratoga
8eltser
Sea Water
'Watered
1
Pond.
Fond.
C. Spring.
Spring.
Brit Chan.
Dead Sea.
.•0880
•1590
1-6266
•2685
•7660
traces
2
•0323
27-911
19-6663
12-9690
27-9690
78-650
3
...
...
•0326
...
traces
...
4
•0808
•1644
...
...
...
28-220
5
•0764
...
...
...
8-666
50-950
6
...
...
...
...
...
...
7
•••
...\
•1613
...
...
...
8
•••
...
...
•0290
7-960
9
...
...
•0046
...
traces
...
10
...
•••
•1379'
•2978
...
...
11
•••
...
...
...
...
...
12
•*•
1-2190
...
...
1-4060
traces
13
•1020
1-9768
...
...
2-2960
...
14
...
•4478
...
...
...
...
16
•••
•••
•1004
...
...
•••
16
•••
...
...
•0007
...
•••
17
...
•2810
...
•0020
...
...
18
•0800
...
•0069
...
...
...
19
•0300
•6569
•1112
•2265
...
...
20
...
...
•8261
4-6162
...
...
21
•*•
...
...
•0014
...
...
22
...
...
•0672
•0144
...
...
23
•2380
•9894
5-8531
1-4004
•0380
...
24
•0630
•1698
41155
1-6000
...
...
25
...
...
•0202
...
...
...
26
...
...
•0173
...
...
...
27
...
...
...
•0018
...
...
28
•5295
...
...
...
...
...
1-2220
32-7671
84-7462
21-2982
85-255
165-770
in 100
e. in.
10-719
10-818
114-
126-
Author.
Author.
Schweitzer.
Starve.
Schweitzer.
Author.
No. 7 is the well-known " Congress Spring." No. 8 is a cele-
brated German Spa.
No. 10 was collected by J. D. Sherwood, Esq., April, 1848,
near the mouth of the Jordan.
Digitized by VjOOQ IC
M4
APFMRDIX.
ABSTRACT
Of the Table of Lewis, shouting the proportion by weight of absoiuta
or real alcohol m epirilt of different densities.
111
m
111
•».gr.ftt 60°.
F*
89.gr. at 60°.
a*1
8p.gr. at 00°.
2*1
0-796
100
0-881
66
0-956
32
0-798
99
0-883
65
0-957
31
0-801
98
0-886
64
0-968
80
0-804
97
0*889
63
0-960
29
0-807
96
0-891
62
0-962
28
0-809
96
0-898
61
0-963
27
0-812
94
0-896
60
0-966
26
0-815
93
0-898
69
0-967
25
0-817
92
0-900
68
0-968
24
0*820
91
0-902
67
0*970
23
0-822
90
0-904
66
0-972
22
0-826
89
0-906
65
0-973
21
. 0-827
88
0-908
64
0974
20
0-880
87
0-910
63
0-976
19
0-882
86
0-912
52
0-977
18
0-886
86
0-916
61
0-978
17
0-888
84
0-917
60
0-979
16
0-840
83
0-920
49
0-981
15
0-848
82
0-922
48
0*982
14
0-846
81
0-924
47
0-984
13
0-848
80
0-926
46
0*986
12
0-861
79
0-928
45
0-987
11
0-868
78
0-930
44
0-988
10
0-866
77
0-933
43
0-989
9
0-867
76
0-986
42
0-990
8
0-860
75
0-937
41
0-991
7
0-868
74
0-939
40
0-992
6
0-866
73
0-941
89
0-867
72
0-948
88
0-870
71
0-945
87
0-872
70
0-947
86
0-874
69
0-949
85
0-876
68
0-951
84
0-879
67
0-958
33
Digitized
byGoogk
INDEX.
The reference* are to the number* of the section*.
Acetoi* 736.
Acetamid, 750.
Acetates, 744.
Acotonitryl, 750.
Aoetene, 723.
Aoetene, perchloric, 725.
Aceton, 752.
Acetic acid, quick process for, 741.
Acetic ether, 750.
Acetic amylic ether, 7-59.
Acetamid, 686.
Acid, acetic, 739 j benzoic, 788; aco-
nitic, 814; acrylic, 763; adipio,
773; allophanic, 862; allanturic,
873; alloxanic, 874; anthropic,
769 ; anisic, 795 ; antimonic, 605 ;
anthranilie,843; amygdalic, 828;
amalio, 878; arsenic, 610; arseni-
ous, 609; aspartic, 814; benzo-
glycoilic, 872; boracio, 387; bro-
mic, 296; bromohydric, 430;
butyric, 764; camphoric, 800;
capric, caproio, caprylie, 764;
carbazotio, 790; carbonic, 366,
688 ; carminio, 837; cerebric, 912 ;
cerotic, 761; chloracetic, 750;
chloric, 290 ; chlorochromio, 574 ;
chlorohydric, 424; chlorus, 292;
cholic, 879; cholalic, choloidic,
cholonic, 879 ; choletc, 880; chro-
mic, 574; cinnamic, 796; oitra-
conic, 814; citric, 814; columbio,
594; cuminic, 793; cyanurio,
856; dialurio, 876; elaidic, 769;
enanthylio, 766; ethalic, 760;
evernic, 835; ferric, 566; ferro-
cyanic, 866 ; fluoboric, 390 ; fluo-
hydric, 433; fluosilicic, 385; for-
mic, 756; fulminic, 858; gallic,
815; glycollic, 871; hippuric, 871;
humic, 921; hydriodic, 431;
hydrobromic, 430; hydrochloric,
424; hydrocyanic, 844; hydro-
fluoric, 433; hydroselenic, 439;
hydrosulphurio, 435; hyperiodic,
801; hyooholio and hyocholalic,
881 ; hypochlorous, 291 ; hypochlo*
ric, 292 ; hydrotellurio, 439 ; hypo-
nitric, 345 ; hypophosphorous, 352;
iodic, 301 ; inosinic, 902 ; iodohy-
dric,431; isatinic, 843; kinic, 819;
lactic, 699 ; lecanoric and lecano-
rinic, 834; lithic, 873; malic, 812;
manganic, 560; margario, 767;
meconic, 820; metaoetonic, 752;
mellisic, 761; malamic, 814;
mesoxalic, 874; molybdic, 594;
nitric, 334 ; nltromuriatic, 429 ;
nitrophenisic, 790 ; nitropicric,
790 ; nitroprussic, 868 ; nitrosali-
cylic, 830; nitrous, 344; oleic,
768; opianic, 820; orselinic, or-
sellic, 834; oxalic, 807; bxamio,
808; palmitic, 767; parabonio,
877; para-steario, 767; pectic,
704; pelargonic, 766; perman-
ganic, 560 ; phocenic, 766 ; pyro-
gallic, 815; phosphorus, 353;
phosphoric, 354; picric, 790;
pimelic, 773; pimaric, 803; pla-
tinocyanic, 869; propionic, 752;
prussio, 844; pyroligneous, 742;
quinic, 819; racemic, 811; mec-
onic, 820; ricinoleic, 770; rubery-
thric, 836 ; saccharic, 701 ; sali-
cylic, 79-1 nad SJJ0 ; aobftcic, 773 ;
splenic, S27 ; eclenhyttric, $S9 >
sek'niousj 337 ; silicic, b81 ; stan-
nic, 597; stearic, 767; suberic,
succinic, 773; sulphamylic, 758;
sulphomethylio, 754; sulphutha-
Uo, 760 ; eulphoriaio, 726 ; eul-
phindigotic, S4£; chlotauutic,
750; sulphocyanic, 851; sulpho-
benzenic, 789; sulphydric, 435;
sulphoglyeeric, 764; sulphurous,
310; sulphuric, 315; sulphopur-
puric, 842; sylvic, 803; tannic,
815; tartaric, 809; tartramic,813;
toluylic, 793; telluhydric, 439;
tellurous, 328; thionuric, 876;
titanic, 594; trigonic, 862;
646
Digitized
byGoogk
646
INDEX.
tungstie, 594 ; ulntie, 711 ,• vie,
871, 873; ralerio (valerianic), 759;
xanthio, 732.
Adds, t*tty, list of, 771 j vegetable,
806; vinie, 720; monobasic, bi-
basie and tribune, 648; con.
pled, 652; named, 249; of the
•line and of bile, 871; theory of,
481,646.
Aeonitine, 825.
Aerolin,762.
Affinity, chemical, 265; eireumstan-
oes which influence, 268.
Agriculture, chemittry of, 920.
Air-pomp, 22; syringe, 125.
Air, analysis ©^ 332.
Alabaster, 537.
Alanine, 860.
Albumin, animal, 883; vegetable,
884.
Alcohols, 717 ; products of its oxy-
dation, 736; amylie, 758; me-
thylic, 753; sulphur, 719.
Alcohols and aeids, relations of,
720.
Aldehyd, 736; sulphur aldehyd,
738.
Algaroth, powder of, 606.
Alizarine, 836.
Alkanet, 837.
Alkalimetry, 497.
Alkaloids, of the alcohol series, 776 ;
vegetal, 816; of ammonia, 817;
of cinchona, 818; of opium, 819.
Aloargen, 783 ; alcarsine, 782.
Allantoine, 873.
Alasarine, 836.
Alloxan and Alloxantine, 875.
Alloys, 473.
Almonds, essential oil of bitter, 785.
Alumina, 549 ; acetate of, 744; sili-
cates of, 551 ; sulphate of, 550.
Aluminum, 548.
Alums, 550.
Amalgams, 473; Amalgamation, 191.
Amarine, 787.
Ammeline and ammelid, 857.
Amids, anhydrid, 686.
Ammonia, 440, 681 ; origin of, 441 ;
acetate of, 744 ; bin-iodized, 681 ;
hydrosulphuret of, 520; oxalu-
rate of, 877; present in the at-
mosphere, 331; stibethic, 781;
trichlorinized, 681 ; salts of am-
monia, 519 ; water of, 446 ; thio-
nurate of, 876; salts of, 683.
Ammonium, 518; compounds of,
619 ; cyanid, 846 ; ohlorld of, 519 ;
sulnhuret of, 520.
Ampere's theory, 203.
Amygdaline, 828.
Amylie ether, 758.
Amylie alcohol, products of its oxyd*
ation, 759.
Amylol, 701, 758.
Amylamine, 778.
Analysis of organic bodies, 664.
Anhydrous sulphuric acid, 820.
Aniline, 792; nitric, 792.
Aneroid Barometer, 30.
Anilids, 792.
Anethol, 795.
Animal electricity, 220.
Animals, nutrition of, 916; food o£
924.
Anthracite, 712.
Anthraeen, 715.
Antimony, 604; oxyds of, 60S;
chloride of, 606; glass of, 605;
sulphurets of, 607; tartrate of,
and potash, 607.
Aphlogistic lamp, 410.
Aqua regia, 429; ammonia), 446;
fortis,334.
Arbor Diana), 627; Batumi, 587.
Argol, 809.
Archil, 834.
Aricine, 819.
Aragonite, 540.
Arrowroot 705.
Arsenic, 608 ; as a poison, detection
of, 613; chlorid of, 611; oxyds
of, 609 ; Marsh's test for, 6)3 ; re-
duction of, 608; metallic, 608;
arsenic acid, 610; Keinseh's test,
613; sulphurets of, 611.
Arseniuretted hydrogen, 612.
Arsine, 782.
Artesian wells, temperature of, 81.
Ashes of plants, 920.
Asparagine, 814.
Atmosphere, chemical history ei,
331; analysis of, 332 ; mechanical
properties of, 20 ; weight of, 25,
26, 27, 31; determination, den-
sity of, 39; limits of, 32.
Atomic weights, table of, 238; vo-
lumes, 260.
Atoms, 13; specific heat of, 261;
polarity of, 42.
Atropine, 825.
Attraction of gravitation, 10; che-
mical, 8 ; mechanical, 8 ; capilla-
ry, 16.
Digitized
byGoogk
index. 547
Aurum Musivuin, 599.
Azote, see Nitrogen f 329,
Balsams, 796,
Ba ri an ! , 526,
Barometer, 2?, 29; Aneroid, 3*.
Bar! ay-sugar! 601.
Baryta, 527; carbonate of, £30;
nitrate of, 629; sulphate of.
529.
Batteries, galvanic, 100; Grovea',
ISJ5; Bunsen's, 196 ; frog, 221 ;
Daniels', 193; Smee'e, 192.
Beeswax, 761.
BenEamide, 766 ; Benzoine, 78 7.
Benzene, or Benzole, 7B9.
Bensoline, 787, 825.
Benadle, 787 ; Beuionitryl, 788,
Beniopbcnon, 793.
BeusoKalidae, 831.
Ben 10 helicine, 831.
BsnzoiJol, 651, 736 j chlorinized,
786,
Bik, 905; adds of, 870.
Biliary calculi, 881,
Bibaric acids, 643.
Ekmuth, 600 ; oxyd of, 601 ; nitrate
of, 602 ; fusible alloy, 003.
Bituminoua coal, 711.
Bleaching powders, £41.
Blood, 890; color and globules of.
900, '
Blowpipe, compound, 411; mouth.
463.
Blue pill, eiT.
Boiling, phenomena of, 130 ; in va-
cuo, 133; boiling-point, 128; ele-
vated by pressure, 136-
Bones, 913.
Bouquet of wine, 766,
Boron, 380; compound witb oxygen,
387 ; with hydrogen, 3S3; chlorid
of, 389; fluorid of, 390.
Borax, 516,
Brain and nervous matter, 912,
Blight's disease, 909.
British gain, 705.
Bromine, history of, 294 ; properties
of, 295.
Bromic ether, 723.
Brucine, 621.
Butterandbntyrine,outjrotB 764;
butter of antimony, 60G,
Buffy coafrof blooO, 900.
Burning oil, 797.
Cadmium, 584.
Caffeine, 823.
Calcareous spar, 510.
Calcium, properties of, 633 ; ohlond
of, 630 j fluortd of, 638 ; oxyd of*
534.
Calorie, 79 ; Calorimetry, 117,
CulonK, urinary, 90S,
Calomel, 019.
Campbene, 797,
Camphor, 800; Borneo, 891.
Cano sugar, 891,
Candles, stearine, 773,
Calculi, biliary, 881.
Caoutchouc, 804;
Capacity for heat, 117,
Capillary attraction, 16,
Caprylo!,774.
Caustic potash, 489.
Carbonic acid, 683 and 366; lique-
faction and solidification of, 161 ;
how removed from wells, 370; of
atmosphere, 371; constitution of,
372; theoretical density of, 657.
Carbonic oxyd, 373 and 689,
Carthamus and carthomine, 837.
Caprylol, 774,
Carburettod hydrogen, heavy, 450.
_ " " light, 450,
Carbon, 357; bisnlphuret of, 376;
eompounda with hydrogen, 459 ;
nitrogen, 377; compounds with
oiygen, 366; oxyd of, 373; den*
pit j of vapor of, 657; aeries, che-
mistry of, 638.
Cartesian devil, 33,
Castor oil, 770,
Casein, 883; vegetable, 884; cflan-
ges to a peculiar fut, 890,
Cathode, 227.
Catalysis, 271*
Catalan forge, 570.
Catechu, 615.
Cajsius, purple of, 631*
Cellubsc, 707.
Cerium, 556.
Ceruse, 588,
Cerotal, 761.
Chameleon mineral, 560.
Charcoal, 362 ; absorbs gases, 315 j
and odors, 364
Change of state by heat, 12],
Chemical transformations, 642.
Chloral, 738.
Chlorimetry, 541,
CMoropbyle, 838.
Chemical affinity, 265 ; nt traction,
8 ; nomenclature, 243 : philoso-
phy, 235.
Cinchona bark, 818,
Digitized
byGoogk
J
648
INDEX.
Cinchonine, 818 ; bichloric and bi-
bromie, 819.
Chinovatine, 819.
Chlorine, preparation, 282 ; and pro-
parties, 284 ; allotoopism of, 288 ;
compounds with oxygen, 289;
passive condition, 423.
Chloroform, 756.
Chlorocarbonie oxyd, 875.
Chlorarsine, 782.
Chelesterine, 881.
Chromium, 671 ; oxyd of, compared,
672; ehloridof, 574; compounds
with salt* of, 675.
Citric acid, 814.
Citraoonid, 814.
Cinchona, alkaloidf of, 818.
Chyle, 908.
Classification of elements, 272.
Clearage of crystals, 61.
Coal, 861 ; gas from, 468 ; products
of its distillation, 715.
Coal tar, 716.
Cold, greatest natural, 152.
Cobalt, 580; ohlorid of, 580.
Cobaltocyanids, 869.
Codeine, 820.
Cohesion, 11 and 14; of fluids, 15;
of gases, 19.
Colors, complementary, 70.
Colomb's electrometer, 168.
Collodion, 710. .
Coloring matters described, 833;
red, 836; from lichens, 834; yel-
low, 838.
Columbium and Columbite, 594.
Compounds, how named, 243.
Combination, mode of, in organic
bodies, 642.
Combination, laws of, 239 ; by vo-
lume, 257 and 656; by direct
union, 654.
Combustion, a source of heat, 80 ;
nature of, 457 ; heat of, 458 ; and
structure of flame, 457 and 460.
Complementary colors, 70.
Congelation, 123.
Conine, 827.
Conduction of heat, 88.
" « in curves, 90.
Convection of heat, 94.
Copper, 590 ; aoetate of, 749 ; al-
loys of, 593; nitrate of, 593;
oxyds o£ 591 ; sulphate of, 592.
Cornudum, 549.
Copal, 803.
Corpuscles of blood in frogs tad
man, 896.
Cotarnine, 820.
Corrosive sublimate, 619.
Cream, 910.
Cream of tartar, 809.
Creatine and creatinine, 901.
Cryophorus, 148.
Crystallisation, dreumstanoes influ-
encing it, 41 ; nature ol* 40.
Crystalline forms, 43.
Crystals, measurement of, 52.
Culinary paradox, 134.
Cupellation, 623.
Cyanates, 848.
Cyanids, 844 ; complex, 866 ; double,
853; relations to alcohol series,
859.
Cyanid of potassium, 846.
Current, passage of in cells of a bat-
tery, 185 ; strength of, 186 ; se-
condary, 214.
Cuminal, 793; Cumene, 793.
Cudbear, 833.
Cyamelid, 848.
Cyanoxosulphid, 851.
Cyanogen, 877, 847.
Cyanic compounds, 844.
Cyanates, 848.
Cyanethene, 859.
Cyaniline, Cyamelaniline, and Cv-
anharmaline, 863.
Cyamellurate of potash, 852.
Cymen, 793, 801.
Darnell's battery, 193.
Davy's safety lamp, 464.
Decomposition of water, 224, 400.
Deflagration, 198.
De La Rive's ring, 205.
Density of vapours,142,656, and 676*
Desiccation, 321.
Daturine, 825.
Destructive distillation of wood, 713.
Dew, formation of, 144; point, 144.
Daniels' hygrometer, 146.
Dextrine, 705.
Diabetes mellitus, 692, 968.
Diabetio sugar, 908.
Diamond, history and forms of, 358.
Diachylon, plaster, 586, 764.
Diastase, 706.
Dicyanid, perchloric, 855.
Didymium, 556.
Diffusion of gases and vapours, 147
Digestive prooess, nature of, 904.
Dimorphism, 264.
Digitized
byGoogk
JUDEX.
549
Dipping needle, 100,
Distillation of alcohol, 717*
DyHlyaioo, 879-
Dobereider's observation, 409.
£u Fay's hypothesis, 172-
Dutch liquid, 454 and 735.
Earth's magneti hsu, 159.
Eel, electrical, 222.
Eggs, 911,
Elasticity of air, 21,
Electrical machines, 166.
Electrical excitement, 164; eel, 222;
polarity, IBS*
Electricity, 153 ; conductors of, lfl9j
of high steam, 17 8 ; statical, 163 ;
distribution of, 170; magneto, 21 7;
thermo, 21 8; animal, 220; theo-
ries of, 172.
Electricity of chemical action, 179 ;
effects of, 187; constant light
from, 200.
Electee -chemical decomposition,
223; conditions of, 22$; theory
of, 233; magnet ism, 201; mag-
netio telegraph, 211 ] metallurgy,
234; plating, 870.
Electro -magnetic motions, 210, 216*.
Electro-magnets, 207.
Electrolysis, 227 ; order of, 231.
Electrophoras, 177.
Electroscopes, 167*
Electro type, 234,
Elements, defined, 13 ; table of, 238;
laws of combination, 235, 230;
non-metallic, classified, 272.
Emetic, tartar, C07 and 810.
Emetine, 825,
liutii'.- in--, 828.
Endusmo^d and exosmose, 13.
Epsom salts, 545.
Equivalents, table of, 238.
Equivalent proportions, 239.
Equivalent substitution, 643.
Ethal, ethol, 760.
Ethammonium, 777-
Etb amine, 777.
Ether, amy lie, 758; acetic amylie,
759; butyric, 765 1 chloric, 755;
hydrohromio, 723; ehlorohydrie,
723; hydriodie, 723; hyponitric,
725; hydrovinie, 727; lumiuife-
rout, bh't leeanorie, 831; nitric,
nitrous, 724-5; oxalic, 80S: puis
chloric, 725; silicic, 733; sulphu-
ric, 730.
Ethers, 723.
lEtberilene and ethorine, 735.
Eucblorine, 291,
Etidiometry, 332; by hydrogsiu
405, 407.
Eupion, 714*
Evaporation, 140; influence of pres-
sure on, 141; cold produced by,
143,
Expansion by heat, 100 ; of solids,
101; of liquids, 100, 102; of gases,
105; of water, 103; beneficial re-
suite of, 104.
Faraday's researches in magnetism,
161 ; In liquefaction, 150; in elec-
tricity, 227,
Eats, and substances derived from
them, 775.
Feldspar, 551.
Fermentation by proteins bodie%
891 and 691; butyric, 700; vis-
cous, 697.
Ferripum and ferrosum, 649.
Ferrocyanuls, &&u*
Ferriayauids, 867.
Fibre, woody, 707.
Fibrin, animal and vegetable, 882,
883; change of, by potash, 889;
by moisture, Ac, 890.
Flame, structure of, 400; of the
mouth blowpipe, 463; effects of
wire gauze on, 464.
Flesh fluid, 901.
Fluidity, 121 ; beat of, 122.
Fluorine, 302.
Fluor-spar, 538,
Fluids, properties of, 15 ; oonduoticm
of heat in, $2.
Food of animals, D24.
Form en e, tri-ehlorinhod, 755.
Formulas, divisibility of, 659.
Fmoklinian hypothesis, 172,
Freezing mixtures, 124*
Friction, a source of beat} SO,
FrogJfl legs, 173, 180, 221.
Fulminates, 858.
Fungi in fermentation, 695 and 893
Fousel oil, 758,
Fusible metal, C03.
Galena, f>85.
Gall-nuts, 815.
Galvanism, 179; quantity and io
tensity in, 186.
Galvanic batteries, lttO-6.
GalvanOBCopes, 202.
Gases, laws of the cend action of
neat in, 93; diffusion and effusion,
147; passage of through mem*
branesjliO; liquefaction of, U0j
Digitized
byGoogk
660
INDEX.
management o£ 280; combine by
volume, 257.
Gasholders, 281.
Gastrie juice, 904.
Gay Lussao's silver assay, 623.
Geine, 711.
Gelatine, sugar of, 895.
Germination of seeds, 900.
German silver, 579.
Glass, 552; manufacture ot, 554.
Glauber's salt, 509.
Gludnum, 550.
Glucose, 692.
Gluten, 884.
Glycerides, 702.
Glycerine, 702.
Glyooooll and glycoeine, 872.
Gold, 028; oxyds and chloride of,
030; wash, 031.
Goniometer, common, 52; Wollas-
ton's, 53.
Goulard's extract, 740.
Grape sugar, 092.
Graphite, 300.
Grove's battery, 195.
Guano, 923.
Guarana, 823.
Gum, 703; elastic, 804; resins, 803;
Gun cotton, 710.
Gunpowder, composition of, 501.
Gutta peroha, 805.
Gypsum, 537.
Hardness, 14.
Hare's blowpipe, 411.
Harmaline, 803.
Hartshorn, 445.
Heat, 79; communication of, 83,
absorption of, 86 ; convection of,
94 ; conduction of, 88 ; expansion
by, 100 ; properties of, 82 ; radiant,
84, 97; solar, 80; sources of, 80;
specific, 117; transmission of, 90;
latent, 122.
Heavy spar, 529.
Helicine, 830.
Helix, 204; contracting, 200.
Hematosine, 897.
Hematite, red and brown, 589.
Hematoxyiine, 837.
Hemming's safety tube, 412.
Henry's coils, magnets, 208, 213.
Homologous bodies, 001.
Honey, 692.
Horns, 914.
Humus, 921.
Hydrobenzamide, 787.
Hydraulic line, 535.
Hydrogen, 391; properties, 895}
nature of, 405 ; acids, 422 ; action
with chlorine, 423 ; arseniuretted,
612; bromine, 430; carbon, 450;
chlorid, 423; fluorine, 433 ; iodine,
431 ; nitrogen, 440 ; oxygen, 399 ;
phosphorus, 448 ; binoxyd of, 420;
selenium, 439 ; sulphur, 435 ; per*
oxyd of, 420; specific gravity ot,
295.
Hydrometer, 87.
Hydrosulphuret of ammonium, 520.
Hygrometers, 145, 140.
Hypochlorite of lime, 541.
Hyoscyamine, 826.
(Imponderable agents, 11.
indigo, 839.
Indigogene, 840.
Induction of magnetism, 150 ; of a
secondary current, 214; of elec-
tricity on telegraphic wires, 212.
Ink, black, 815 ; sympathetic, 580.
Insulators of electricity, 109.
Intensity, quantity, 180.
Interference of waves, 58, 69.
Iodoform, 756.
Iodine, 297; compounds with oxy-
gen, 301.
Ions, 227.
Iridium, 036.
Iron, 663; ferrooyanid, 867; ores
of, 569; pure, 664; chloride, 567;
pyrites, 567; phosphate, 568;
acetates, 744; lactate of, 700;
oxyds of, 600; reduction of its
ores, 509 ; salts of, 508 ; specular,
500,* sulphurets of, 507.
Isatine, 843.
Isinglass, 894
Isomerism, 800.
Isomorphism, 202.
Eakodyle, 782; protoxyd of, 788.
Eermes mineral, 007.
Kino, 815.
Ereasote, 713.
Eyanite, 551.
Eyanising process, 019.
Lactates, lactide, 700.
Lactose, 093.
Lakes, 550, 836.
Lamp,Davy'8 safety,464;Argand,462.
Lantanium, 556.
Lard oil, 768.
Laughing gas, 338.
Law of divisibility of formulas, 659.
Law of chemical transformations,
642.
Digitized
byGoogk
INDEX.
551
Lead, 535; acetates of, 745, 746;
carbonaie of, 588 1 o*yds of, 536 ;
plaster or diachylon, 586; preei-
pitated by sinc,587; snip buret, 585.
Leather, 694,
Lecauorine, 83 4k
Legumcn, £84.
Leiocome, 705.
Leyden jar, 173; dissected, 175,
Leucine, HSS.
Light, 54; interference of, 59; po-
larisation of, 72; properties of,
61 ; sources and nature of, 55 ;
analysis ofT 68 ; chemical rays of,
75, 76,* vibrations of, 60.
Lignin, 707*
Lignite, 712.
Lime, 534; carbonate of, 540 ; hypo-
chlorid of, 541 j lactate of, 700;
phosphate of, 539 ; sulphate of,
537;
Liquefaction, 122; and solidification
of gase?, 150.
Liquids, properties of, 15, 92.
Litharge, 586.
Lithium and Hthia, 517.
Litmus, 835*
Lodestone, 154.
Logwood, 837,
Lunar caustic, 627,
Luteoline, 338.
Lymph globules, 896.
Madder, 830.
Magnesia, 5 13 • carbonate of, 510;
calcined, 543; sulphate of, 545.
Mngncsian minerals, 547.
Magnesium, 542; ehlorid of, 544;
oxyd of, 543.
Magnetism, 154; induction of, 156;
of the earth, 159.
Magnetics and diamagnetics, 161.
Magnets, 157.
Magnets, electro, 207.
Magneto-electricity, 217.
Magnus, green salt of, 685,
Malachite, green and blue, 590.
Mai amid, 814,
Malt, aetion of on sugar, 706*
Mutates, 812.
Malleability of metals, 470.
Manganese, 557; chlorida of, 561;
oxyds of, 558; salts of, 562,
Mannite, 693.
Manure?, 920.
Marble, 540,
Margarine, 767*
Mariotte's law, 24.
Marsh's test for arsenic, 613.
MaEeicot, 536.
Matter, general properties ot, 4- j
divisibility of, 12.
Matteucci's researches, 220.
Melting-points, 121.
MelHsoI, 761.
Mellon, 852.
Mdloni's researches, 97.
MaUm, S52.
Melamine, 857.
Melaoiline, 863,
Me reap tan, 719.
Mercury, 615; double amide ofp
619; chlorids of, 619; fulmiuat*
of, 858 ; iodida of, 620 ; nitrates
of, 621; oxyds of, 81 -S ; sulphate
of, 621 ; snlphureta of, 620,
Metacetcne, 752*
Metameric bodies, 660.
Metaldcbyde, 737.
Metallurgy, electro, 234
Metals, general properties of, 466 J
physical properties, 469; foii-
bUity, 121 ; oxyds of, 474 ; che-
mical relations of, 474; tenacity
of, 471,
Metallic veins, 467,
Methol, 753 ; oxydation of, 756,
Me thy Ho alcohol, 753,
Me thy lie ether, 754*
Methamioe, 778.
Microsootnie salt, 513.
Milk, 909; atigar tif, 693.
Mindercus, apirit of, 744.
Miniums, 5Sfl.
Molecules, 13 ; polarity of, 42,
Molybdenum, 591.
Monti b&Bic acids, 648.
Mordants, 550,
,Morine, 838.
Morphine, 819.
Mortar, 535.
Mouth blowpipe, 463.
Muraxid, 877 ; mnrexolne, 878,
Muriatic aeid, 423.
Murray** solution, 546.
Muscular tissue, 837,
Names of elements, 237-
Nascent state, 269.
Naphtha, 716 ; naphthaline, 715.
Nareetine and narccine, 820.
Nervous matter, 912,
Neutrality of salts, 479,
Newton's fusible metal, 603.
Nickel and its oxyds, 577, 578'
sulphate, 579.
Digitized
byGoogk
5tt
IND1X.
Nicotine nd nieotiantoe, 836.
Nitre, 499 ; tweet spirit! of, 726.
Nitro-prussids, 868.
Nitrogen, 329; compounds with
oxygen* 388 ; determined in or-
ganic compounds, 672; chlorid
of, 681.
Nitrons oxyd, 338.
Nitrie oxyd, 841.
Nitryls, 686.
Nomenclature and symbols, 243.
Nordbausen acid, 320.
Nutritive substaneet containing
nitrogen, 882.
Nutrition of plants and animals,
915 ; elements of, 930.
(Ersted's law, 201.
Ohm's law, 187.
■ apparatus for compressibility
of water, 16.
Oil of bitter almonds, 785; of
fousel, 758 ; of castor, 770 ; of
mustard, 802; of roses, 799; of
lard, 767, 797; of palm, 767; of
potato, 758 ; of cumin, 793 ; of
cinnamon, 796; of the Dutch
chemists, 735 ; ofspirea, 793; of
caraway, citron, bergamot, juni-
per, lemon, parsley, 798 ; of tur-
pentine, 797; of winter-green,
795; of vitriol, 319; of horse-
radish, 802.
Oils, volatile or essential, 796.
Olefiant gas, 734, 658; with oblo-
rine, 735.
Oleine, 767.
Opium, alkaloids of, 819.
Orcin and orceins, 834.
Ores, how distributed, 468.
Organic bases or alkaloids, 816.
Organic bodies characterized, 637-
639 ; general properties of, 638 ;
analysis of, 664 ; modes of com-
bination in, 643 and following.
Orpiment, 611.
Osmium, 636.
Oxygen, 274; properties and ex-
periments, 277; allotropio state,
279.
Oxyhydrogen blowpipe, 411.
Oxamethane, 808.
Ozone, 279.
Palm oil, palmatine, 767.
Palladium, 632.
Pancreatic fluid, 903.
Papaverine, 820.
Paracyanogen, 853.
Paranapbthalene, 719.
Paraffin©, 714.
Pascal's experiment, 27.
Pattinson's process for sflvsr, 614
Peat, 712.
Pendulums, 107.
Pern balsam, 796.
Peruvian bark, 818.
Pepsin, 904.
Petalite, 617.
Petroleum, 716.
Phene, 789.
Phenol, 716, 789; trinitric, 790.
Phloretine, pbloridxine, phlorixelns,
832.
Pboconine, 766.
Phosgene gas, 689.
Phosphorescence, 78.
Phosphoric acid, hydrates of, 355.
Phosphorus, 346; red or amor-
phous, 349 ; chlorids, bromids,
356; compounds with oxygen,
350.
Phosphnretted hydrogen, 448.
Piperin, picoline, and piperidine,
822.
Plants, their nutrition, 915.
Platinocyanids, 869.
Platinum, 633 ; chlorids and oxyds,
635 ; power to cause the union of
gases, 409; sponge and black,
634.
Plumbago, 360.
Polarization of light, 72.
Polarity, electrical, 155, 165; of
molecules, 42 ; magnetic, 155.
Polecat, secretion of, 802.
Populine, 831.
Polycyanids, 853.
Polymeric bodies, 660.
Potash, 488 ; acetate of, 744 ; alumi-
nato of, 549 ; carbonates of, 495,
496 ; chlorate, 502 ; chromate of,
575 ; argentocyanid of, 870; cy-
anate, 850; nitrate, 499; salts of,
494 ; sulphates of, 498 ; tartrate
of, 809; yellow prussiate, 865;
red prussiate, 867.
Potassium, 483; properties, 485; per-
oxyd of, 487; tests for, 490; sulphu-
rets, 492 ; chlorid, bromid, and io-
did, 491 ; cyanid, 844, 846 ; ferri-
cyanid of, 867 ; ferrocyanid, 865 J
mellonid of, 852 ; oxyds of, 487.
Potato oil, 758. *.
Pottery, art of, 555.
Pneumatic trough, 280.
Digitized
byGoogk
INDEX.
553
Presence of a third body, 271.
Prussian bine, 866.
Pruseio acid, 844.
Prussiate of potash, 865.
Prism, its action on light, 67.
Prismatic colors, 69.
Protein©, 882 ; relation to albumen,
fibrin, and casein, 883 ; analyses
and constitution of, 887; changes
of, 888, 890.
Pulse glass, 135.
Purple of Cassius, 631.
Pyrometer, 114.
Pyroxylio spirit, 753.
Pyroxyline, 710.
Pyrophorus, 492.
Quantity and intensity, 186.
Queroitrine, 838.
Quicksilver, 615.
Quinine, 818 ; Quinidine, 819.
Quinoline, 819.
Raoemio acid, relations to light, 811.
Radiation,terrestrial, 81; of heat, 84.
Radicals, salt, 480.
Ratsbane, 609 ; realgar, 611.
Red lead, 586.
Red precipitate, 618. [63, 64.
Reflection and refraction of light,
Refraction, index of, 65 ; double, 71.
Renne^ 910.
Repulsion, 8.
Residues of substitution, 653.
Resins, 803.
Reinsoh's arsenic test, 613.
Respiration, 926 ; olements of, 924.
Rhodium and its compounds, 636.
Rochelle salt, 809.
Ruthenium, 636.
Sago and salep, 705.
Safety lamp, 465.
Sal-ammoniac, 443.
Salicine, 794, 829.
Salicylol and its derivatives, 794,
829.
Salicylamid, 795.
Saligenine, saliretine, 829.
Saliva, 903.
Salts, theory of, 477; haloid, 480;
neutrality of, 479.
Salt, oommon, 508 ; of sorrel, 808.
Salt-radical, 481.
Saltpetre, 499.
Sarcosine, 901.
Sandal wood, 837.
Sanguinarine, 825.
Saxon blue, 842.
Secondary currents, 214.
Selenium, 825; oxyd of, 826.
Selenite, 537.
Serum and seroline, 898.
Sesqui-oxyds and salts, 649.
Silica, 381.
Silicio ethers, 733.
Silicon, 379; chlorid of, 384; flue-
rid of, 385.
Silver, 622 ; oxyds of, 625 ; chlorid
of, 626 ; nitrate of, 627; fulminate
of, 858.
Sinamine, 802.
Smee's battery, 192.
Soaps, 764.
Soda, 507 ; acetate of, 744 ; biborate
of, 516; carbonates of, 510 ; nitrate
of, 511; phosphates of, 512; sili-
cates of, 552 ; sulphate of, 509.
Sodium, 505 ; chlorid of, 508.
Soils, relation of to plants, 920.
Solanine, 825.
Solids, properties of, 14; expansion
of, 101.
Solidification of gases, 150.
Solubility of sal soda, 509.
Soluble tartar, 809.
Solution, 267.
Spathio iron, 568.
Specific gravity, 33; rule for, 34;
of gases, 39.
Specific heat of bodies, 117.
Spectrum, prismaUo, 68; fixed linee
in, 69.
Spermacoti, 760.
Spheroidal state of bodies, 131.
Sptrea ulmaria, oil of, 793.
Spodumene, 517.
Spirits of wine, 717; of nitre, 725.
Spinel, 549.
Starch, 705.
Stalactites, 540.
Stibethine, 781.
Steam, 126; latent heat of, 138;
elastic force of, 136 ; engine, 139.
Stearin, 767; candles, 772.
Stearoptens, 800.
Steel, 570.
Stibium, 411.
Strontium, 531 ; chlorid of, 532.
Strychnin, 821.
Styrax balsam, 796.
Substitution, equivalent, 643.
Substitution by residues, 653.
Sugar of lead, 745 ; of gelatin, 895.
Sugar of milk, 693.
Sugars, 691 ; products of the.*r de-
composition, 694.
Digitized
byGoogk
564
INDEX.
Sulphamethone, 754.
Sulphamethane, 808.
Sulphovinio add, 726.
Sulphocyanates, 851.
Sulphur, 804 ; compounds with oxy-
gen, 800 ; chlorid of, 324.
SuTphobensid, 789.
Bolphnr auratum, 807.
Sulphuric acid manufacture, 318.
Sulphuretted hydrogen, 435.
Surbasio and biturbaaio aoetate of
lead, 745, 748.
Sustaining batteries, 192.
Symbols, chemical, 253.
Tanning, 815.
Table of chemical equivalents, 238.
Tannin, 815.
Tartar emetic, 810; tartrates, 810;
crude tartar, 809.
Tartramid, 813.
Tapioca, 705.
Taurine, 880.
Telegraph, electro-magnetic, 211.
Tellurium, 328.
Temperature of flame, 461 ; of in-
candescence, 459.
Terebol, 799.
Terpinol, 799.
Tenacity of metals, 471.
Thebaine, 820.
Theine, 823 ; theobromine, 824.
Thilorier's apparatus, 151.
Theories of electro-chemical decom-
position, 233 ; of substitution, 643.
Thermo-electricity, 218.
Thermometers, 109 ; Bregnetfs, 115;
graduation, 111 ; thermo-eleotrio,
97 ; self-registering, 112.
Thialdin, 793.
Thorium, 556.
Thiosinamine, 802.
Tin, 595; alloys of, 596; oxyds of,
597; chlorids of, 598, 599.
Tissues, waste of the animal, 926 ;
oellular and vascular, 707.
Titanium, 594.
Tobacco, alkaloids of, 825.
Tolu, balsam, 793.
Toluen, 738.
Triethamine, 779.
Tricyanid, 855.
Toueh, sense of, 91.
Tournsol, 834.
Turmeric, 838.
Turnbull's blue, 867.
Transmission of radiant heat, 98.
Tungsten, 594.
Turpeth mineral. 62L
Turpentine, oil of, 796.
Tyrosin, 888.
Types, 643.
Ulmine, 711.
Undulations, 56.
Upas, poison of the, 821.
Uramile, 876.
Uranium, uranite, 589.
Urea, 849 ; vinic, 861 ; urine, 907 1
acids o£ 907.,
Ure's eudiometer, 405.
Urinary calouli, 908.
Vacuum, 23; Torricellian, 27.
Valerianates, 759.
Vanadium, 594,
Vapor of alcohol, density ot, 718.
Vaporisation, 126.
Vapors, maximum density of, 142 ;
density of determined, 676.
Vegetal acids, 806.
Vegetable mould, 711.
Vegetables, nutrition of, 915.
Vegetal alkaloids, 816.
Veratrine, 825.
Verdigris, 590.
Vermilion, 620.
Vibrations of light, 60; of heat,
89.
Vinegar, quick process for, 741.
Vinic acids, 720.
Vinol, 717.
Vistus fermentation, 694.
Viscous fermentation, 697.
Visible redness, 459.
Vitality, 8.
Vital heat, 929 ; force, 639.
Vitriol, blue, 592; green, 568; oil
of, 319; white, 583.
Volatile alkali, 445.
Volatile oils, 796.
Volta, his discoveries, 180.
Voltaic pile, 182 ; circle, 183, 184.
Voltameter, 226.
Volume of sulphydric acid, 438;
combination by, 257, 656.
Vulcanized gum-elastic, 804.
Waves, 57, 58.
Water, history of, 414, 678; as a
chemical agent, 419 ; compressi-
bility of, 15 ; capacity for heat,
127; crystalline forms of, 415;
air in, 416; solvent powers of,
417 ; decomposition of, 400 ; vol-
taic, 224; formation of, 397, 401 ;
unequal expansion of, 103; baU
loon, 38.
Digitized
byGoogk
INDXX.
655
Water-hammer, 134.
Wax, 761.
Weight and specific gravity, S3.
Wells, Artesian, 81.
White arsenic, 609; lead, 588.
White precipitate, 619.
Wollaston's goniometer, 53.
Wood, destructive distillation
713; tar, 714.
Wood naphtha, 713.
Wood spirit, 753.
of,
Woody fibre, 707: transformation
of, 711.
Xanthine, 836.
Xyloidine, 710.
Yeasty action of, 892.
Yellow prassiate of potash, 865.
Yttrium, 556.
Zaffire, 580.
Zino, 681; oxyd of, 583 ; chlorid and
sulphate of, 583; lactate of; 700
Zirconium, 556.
m ERIK
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THIS BOOK IS DUE ON THE LAST DATE
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AN INITIAL FINE OF 25 CENTS ^
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WILL INCREASE TO SO CENTS ON THE FOURTH
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MAR 9o t
■*© Ji
JJ8
AHK 18 1941
|
LD 21-95m V37
Digitized by LiOOQ IC
YB 17055
s"
84529
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byGoogk