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AGRICULTURAL

QUALITATIVE AOT) QUANTITATIVE

CHEMICAL ANALYSIS.

E. WOLFF, FRESENIUS, KROCKER, AND OTHERS.

EDITED BY

G. C. CALDWELL,

I>B0FES80B OF AGRIOXTLTtJRAL CHEMISTKY IN THE OORKELL VmrSBSltr.

NEW YORK:
ORANGE JUDD AND COMPANY,

245 BROADWAY.

Entered according to Act of Congress, in the year 1869, by
ORANGE JUDD & CO.,

In the Clerk's Office of the District Court of the United States for the Southern
District of New York.

PREFACE.

The purpose of this work is to supply a complete
manual of chemical analysis, for the use, especially, of
agricultural students.

The qualitative and quantitative processes that are de-
scribed refer only to such substances as are found in soils,
plants, animals, fertilizers, or other materials or products
of agriculture ; and, moreover, in order to reduce the size,
and consequently the cost of the book as much as possi-
ble, except in two or three instances, only those methods
of analysis are introduced which are most commonly
used by good chemists, and have been tried and found
reliable, with such improvements as have been made in
more recent practice.

The chapters on Special Analyses consist, in the main,
of a translation of the " Anleitung zur Chemischen ITn-
tersuchung landwirthschaftlich-wichtiger Stoffe^ von Dr.
Mnil Wolff, 2te Aifflage, 1867," a work of the first au-
thority in Germany ; two or three unimportant matters
have been omitted, the arrangement has been somewhat
altered, and some additions have been made to the original.

The other chapters, on reagents, manipulation, etc., ^re
3

IV PREFACE.

made up largely from the " Anleitung zur Quantitativen
Chemischen Analyse, von Dr. C. JR. Fresenius, 5te

Auflage, 1866."

Concerning late improvements in methods of analysis,
the Zeitschrift far Analytische Chemie, by the same au-
thority, has been frequently consulted.

The scheme of qualitative analysis has worked well in
my own hands, and with my own students, but, neverthe-
less, I would have preferred to give it a more careful
trial before publishing it.

Valuable assistance in testing this and other methods
of analysis has been received from Mr. T. B. Comstock,
while a student in my laboratory.

The use of the old system of atomic weights, and of
the old nomenclature, would doubtless have made the
book more simple to the majority of students at first, but,
nevertheless, it seemed more expedient to follow the com-
mon usage in the best recent works on chemistry. The
same may be said in regard to the use of the centigrade
thermometer and the metric s}stem of Aveights and
measures.

Although the work has been somewhat hastily prepared
to meet a pressing want in my own laboratory, I trust it
may yet be found to answer a good purpose in other lab-
oratories where agricultural chemistry is made a specialty.

G. C. C.

Cornell University^ College of )
Agriculture, August, 1869. f

TABLE OF CONTENTS.

CHAPTER L— Tlte Reagents.

List of the reagents neeclcd, with directions for preparing them, when
not more readily obtained otherwise, and for testing their purity. 7

CHAPTER II.— Analytical IVIanipnlation.

Determination of specific gravity, solution, evaporation, precipita-
tion, filtration (including Buiisen's new method), weijihiug of
residues and precipitates, measuring and dividing solutions, and
calculation of results 23

CHAPTER III.— Keactions and IVIeHiods ol* Qnantita-
tlve Estimation.

Potassium, sodium, ammonium, barium, calcium, magnesium, alumin-
ium, iron, manganese, zinc, lead, copper, and arsenic; silicic,
sulphuric, carjjonie, phosphoric, nitric, hydrochloric, hydrocyanic,
hydroferrocyanic, hydrosulphuric, hydriodic, hydrofluoric, oxalic,
acetic, tartaric, citric, malic, lactic, \iric, hippuric, and tannic
acids; cellulose, starch, gum, the sugars, albuminoids, urea, fat,
and alcohol J^

CHAPTER IV.— Special Mctltods ol* Analysis.

Course of qualitative analysis, estimation of water, of organic mat-
ter, of sulphur and chlorine in organic compounds, special
methods of separation of bases and acids, schemes of analysis. ..128

CHAPTER v.— Analysis of Soils and Rocks.

Mechanical and chemical analysis, and examination of physical prop-
erties, of soils, and examination of marl, limestone, and clay 16.5

VI TABLE OF CONTENTS.

CHAPTER VI.— Fertilizers.

Farm-yard manure, urine, solid excrements, bone-meal, bone black,
bone-ash, phosphorite, guano, superphosphate, gypsum, salt,
potash compounds, and Chili saltpetre 213

CHAPTER VII.— Aslies.
Ashes of plants, of animal substances, and of fuel 241

CHAPTER VIIL— Fodder and Food.

Fodder plants, beets, turnips, potatoes, seeds, meal, flour, milk,
butter, cheese, and vinegar 251

CHAPTER IX.— IVool and Bark.

Examination of wool and tanners' bark 269

CHAPTER X.— Beverages.

Water and wine .271

CHAPTER XI.— Xal»les.

Metric system of weights and measures, atomic weights of elements,
factors for calculating analyses, estimation of tannin in bark, etc.284

AGRICULTURAL

QUALITATIVE AND QUANTITATIVE

CHEMICAL ANALYSIS.

CHAPTER I.

REAGENTS.

The following list contains all the reagents used in the
various courses of analysis described in this book, arranged
in alphabetical order. . Most of them can be procured of
the druggists, or the dealers in apparatus and chemicals.

Directions are given here for the preparation of such
reagents only as cannot be thus obtained conveniently.
The chemical tests to which each reagent should be sub-
jected, in order that the analyst may be assured of its
purity, and the strength of the solutions to be made, are
also given, wlien it is necessary. Most of this information
is taken from the works of Fresenius.

The new system of nomenclature and the new formulas
being adopted in this work, the new name and formula
of each reagent are given first, and, for the benefit of
those who are less familiar with these, the old name and
formula are afterwards enclosed in parentheses, whenever
there is any essential difference between the new and the
old.

7

8 § 1. KEAGENTS.

1. «.— Acid, acetic— HC,H30,. (HO,C,H303. HO, a.)

— This should leave no residue on evaporation, and
should emit no empyreumatic odor when evaporated after
saturation with sodic carbonate ; neither hydrosulphuric
acid, argentic nitrate, nor baric chloride should produce
any change in it, nor amnionic sulj^hide, after neutraliza-
tion with ammonia.

h. Acid, Citric— H3CJI,0,. (3H0,C,,H,0,,.)— Recrys-
tallize it, unless clean and colorless.

c. Acid, hydrochloric — HCl. (Chlorhydricacid. Mu
riatic acid.) — This must be colorless, and it should leave
no residue when evaporated on platinum foil, nor should
it attack the foil ; it should give no blue color to starch-
paper, nor should it bleach starch that has been faintly
colored blue with iodine ; it should give no turbidity with
baric chloride, after having been considerably diluted, nor
should it be colored by hydrosulphuric acid or potassic
sulphocyanate.

For the dilute acid, add the concentrated acid to 4 parts
of water.

d. Acid, hydrosulphuric— H^S. (HS.)— Pour dilute
sulphuric acid through a funnel tube over fused ferrous
sulphide, in a common bottle, and conduct the gas that is
evolved, first through water in a small wash-bottle, and
then into distilled water. The solution should emit a
strong odor of sulphuretted hydrogen, and should be
freshly made.

e. Acid, nitric— HNO3. (HO,NO,.)— This should be
colorless, and should leave no residue when evaporated on
platinum foil ; after having been considerably diluted, it
should not be made turbid by argentic nitrate or baric
chloride. For the dilute acid, add the concentrated acid
to 4 parts of water.

/. Acid, nitro-hydrochloric Aqua regia.— Mix to-
gether 1 part of pure nitric acid, and 3 or 4 parts of pure
hydrochloric acid.

§ 1. EEx\.GEXTS. 9

g. Acid, oxalic,— H^C^O,. (2H0,C,0,.) This should
not present the least appearance of efflorescence ; it
should give a perfectly clear solution with water, and
sliould leave no residue when ignited in a platinum dish.
If the acid does not meet these requirements, it should be
purified by repeated recrystallization.

Stolba {Fresenius^ Zeitschrift 8, 63) recommends subli-
mation as a convenient method of purifying oxalic acid.

Dry the acid thoroughly by keeping it in a warm place
for a considerable time, with occasional stirring ; when a
small portion of it, gently heated in a test tube, gives off
but little water before subliming, it is sufficiently dry.
Put it, then, in a large beaker to the depth of 15-20 mm.,
cover the beaker with a hollow cone of paper, and im-
bed it in iron turnings in an iron dish, to the same depth
as that of the acid inside, and heat it cautiously, raising
the temperature very gradually. Scrape off the outside
of the cone of sublimed acid, separate the more solid yel-
lowish outer part from the white inner portion, and purify
each by itself by crystallization from solution as usual.

h. Acid, sulphuric— H,SO,. (H0,S03). — Common
sulphuric acid usually contains lead, wdiich is precipitated
as a fine w^hite powder, when the acid is diluted with con-
siderable water, or when mixed with 4 or 5 parts of
alcohol; it sometimes gives a red color with a solution of
ferrous sulphate, where the two liquids come in contact (§
62), and, when diluted, gives the reaction for chlorine with
aigentic nitrate (§ 63), and for arsenic by Marsh's test
(§ 57). The pure acid should give none of these reac-
tions, nor any blue color after dilution with 20 parts of
water, when a little starch paste and potassic iodide are
added to the cooled liquid ; it should be volatilized com-
pletely when heated.

The dilute acid is pre}xired by adding the concentrated
acid to 5 parts of water, slowly, and with constant stir-
ring, letting the mixture stand a long time if any plumbic
1* '

10 § 2- KEAGENTS.

sulphate is precipitated, and then decanting the clear su-
pernatant liquid for use.

i. Acid, silicic. — See Quartz.
h. Acid) taniliC) needs no testing.

2, Alcohol.— C^H^O. (C.H^O,.)— This is used both in
its pure state (absolute alcohol), and mixed with water
until its specific gravity is 0.83 or 0.84, corresponding
to about 90° I „ of pure alcohol, by volume.

It should be volatilized completely, and leave no odor
of fusel oil when rubbed between the hands ; it should
burn with a pale blue, barely visible flame, and should
not redden blue litmus-j)aper.

3. a. — Ammonic acetate. — NH.C^HgO^. (Acetate of
ammonia. NHp,C,H303. NIip,A.)— This should be
colorless, free from empyreumatic oclor, and inorganic
acids, and should be completely volatilized when heated.

h. Ammonic carbonate.— (NH J ^003. (Carbonate of
ammonia. NH40,C02.) — This should be completely
volatilized when heated, and, after supers aturation with
nitric acid and heating, should give no reaction with solu-
tions of silver, barium, or ammonic sulphide. Dissolve it
in 4 parts of water, and add 1 part of ammonia. Keep
some of the salt also in the dry form.

c. Ammonic chloride. — ^XH.Cl. (Chloride of ammo-
nium.)— ^This should be completely volatilized when heated
on platinum foil, and should give no reaction with am-
monic sulphide, baric chloride, or litmus. Dissolve in 8
parts of water. Keep some of the salt also in the form
of a dry powder.

d Ammonic fluoride.— NH,F. (Fluoride of ammonium.)
— This, when heated in a platinum dish, should leave no
residue; if impure, it may be purified by sublimation
between two platinum dishes. It should be kept in gutta
percha bottles.

§ 3. REAGKNTS. 11

e. Amnionic hydrate.— NH^HO. Ammoiia JSTJff^.—

This should be colorless, and leave no residue when evap-
orated in a watch-glass : after dilution with its volume of
water, it should give no very marked turbidity with lime-
water, and, after supersaturation with nitric acid in slight
excess, it should give no precipitate or color with argentic
nitrate, baric chloride, or ammonic sulphide.

/. Amnionic molybdate. — (NHJ^MoO^. (Molybdate

of ammonia. KH^OjMoOg.) — Dissolve 1 part of molyb-
dic acid in 8 parts of ammonia-water, pour the solution
into 20 parts by weight of nitric acid (Sp. Gr.=1.2), let
the mixture stand several days in a warm place, and
decant the clear liquid for use. When moderately heated
with excess of nitric acid, it should give no yellow pre-
cipitate.

g. Ammonic nitrate. — ISTH^lSrO,. (Nitrate of ammonia.
NH^O, NO^.) — This should give no reaction with baric
chloride or argentic nitrate, and should be completely
volatilized when heated.

A. Ammonic oxalate. — (NHJ^C^O,. (Oxalate of am-
monia. 2X11^0,0^0^.) — This should be completely vola-
tilized by heat, and should give no reaction with hydro-
sulphuric acid, or ammonic sulphide, or with baric chloride
in a solution acidified with hydrochloric acid. Dissolve
in 24 parts of water.

i. Ammonic sulphate. — (NII,)„SO^. (Sulphate of am-
monia. NH^OjSOg.) — This may be readily prepared by
neutralizing ammonic hydrate with dilute sulphuric acid.

Jc. Ammonic Sulphide. — (NH,),S. (Sulphide of am-
monium. NH^S.) — Conduct sulphuretted hydrogen (§ 1,
cl) into 3 parts of ammonic hydrate as long as the gas
is absorbed, and add 2 parts of fresh ammonic hydrate.
The reagent should evolve sulphuretted hydrogen freely
when mixed with strong acids, and should give at least
only a white precij)itate with them ; it should give no re-

13. § 4. IlEAGEXTS.

action at all with solutions of lime or magtiesia ; when
evaporated in a platinum dish, the residue should be vola-
tilized completely on ignition.

- Dissolve some flowers of sulphur in a small portion of
the reagent, and label this solution, ammonia sulphide
with excess of sulphur,

I Ammonic tartrate.— (N"HJ^ CJ-ip,. (Tartrate of
ammonia. 2XH^O,CgIl40j„.) — Neutralize tartaric acid
with ammonic hydrate, and then add more ammonic hy-
drate, so that it shall be in excess over the acid.

m. Ammonic-ferrons sulphate. — (NHJ^Fc (SOJ^.
(Sulphate of j^rotoxide of iron and ammonia. NH^O,
FeO, (SOg),.) — ^Divide a quantity of sulphuric acid into
two equal parts ; heat one of them with an excess of
small clean iron nails free fi'om rust, as long as the evolu-
tion of hydrogen continues. Neutralize the other portion
of the acid accurately with ammonic carbonate, and then
add a few drops of sulphuric acid, Filter the solution of
ferrous sulphate, obtained by the action of the acid on the
nails, into the amnionic sulphate, evaporate the mixture
a little if necessary, and let it crystallize. Let the crys-
tals drain in a funnel, dry them by exposure to the air 0:1
filter-paper, and keep them in a well stoppered bottle.
The solution of the salt in water acidified with sulpliuric
acid should give no red color with potassic sulj^hocyanate.

4. Argentic nitrate. — AgNO^. (Nitrate of silver.
AgO, NO^.) — After the solution of this reagent has been
completely precipitated with hydrochloric acid, the fil-
trate from the j)recipitate should leave no residue Avlien
evaporated, and the same filtrate should give no color
with ammonic sulphide. Dissolve in 20 parts of water.

All the silver refuse, consisting of precipitates contain-
ing silver, and solutions to which argentic nitrate has been
added, should be tlirown into a bottle containincr dilute
hvdrochloric acid. When a sufficient quantity of the

§ 5. IIEAGENTS. 13

precipitated chloride has accumulated, separate it from
the liquid by decantation of the latter, wash it well with
water, pour diUite sulphuric acid over it, and put some
pieces of zinc in contact witli it.

When the wliolo is changed to a gray metallic powder,
and the zinc is all dissolved, filter out and wash the pow-
der well, dry, and ignite it. Dissolve the silver thus ob-
tained in nitric acid, add water, filter if necessary, evap-
orate the filtrate to dryness on the water-bath, and dis-
solve the residue in 20 parts of water, and subject the
solution to the tests above described.

5. c^— Baric acetate. — Ba(C2H302)„. Acetate of
baryta. BaO,C JI3O3. BaO,A.)— This should be colorless
and should have no empyreumatic odor, and it should
give no reaction with amnionic sulphide or argentic ni-
trate ; after complete precipitation witli sulphuric acid,
the filtrate should leave no residue on evaporation. Dis-
solve in 10 parts of water.

h. Baric chloride. — BaCl^. (Chloride of barium. BaCl.)
— This should not afifcct litmus-paper, nor give any
reaction with amraonic sulphide ; after complete pre-
cipitation with sulphuric acid, the filtrate from the precipi-
tate should leave no residue when evaporated. Dissolve
in 10 parts of water.

c. Baric hydrate. — Ba(HO)„. (Hydrate of baryta.
Baryta water. BaO,HO.) — After precipitation of the
barium from the solution by sulphuric acid, the filtrate
should remain clear when mixed with alcohol, and should
leave no residue when evaporated. Dissolve in 20 parts
of water. In determinations of urea in urine, a mixture
of one volume of a cold saturated solution of baric nitrate
and two volumes of a cold saturated solution of baric
hydrate is used.

cl Baric nitrate.— BaCNO,),. (titrate of baryta. BaO,
NO^.) — This should be completely precipitated by sul-

14 § G. REAGENTS.

phuric acid so that the iiltrate from the precipitate leaves
no residue when evaporated, and it should give no reac-
tion with argentic nitrate.

€. Calcic chloride. — CaCl^. (Chloride of calcium. CaCl.)
— This should not affect litmus-paper, should give no
reaction with ammonic sulphide, nor any ammonia when
heated with sodic hydrate. Dissolve the crystals in 5
parts of water.

The crude, impure, fused chloride answers for desicca-
ting purposes.

/. Calcic fluoride.— CaF^. Fluor spar. — To cave
trouble, buy the powdered fluor sj^ar.

g. Calcic hydrate. — Ca(HO) 3. Lime-water. (CaO,
HO.) — Digest slaked lime with cold water with occasional
stirring, let the mixture stand quietly for a time, and de-
cant the clear liquid for use. It should give a dark color
to turmeric-paper, and a considerable precipitate with
ammonic oxalate.

For many purposes milk of lime is used in preference
to lime-water ; this reagent is simply lime-water, mixed
with an excess of undissolved calcic hydrate. It should
be made with lime from white marble, and should be kept
in well stoppered bottles, and shaken up Avhen used.

A. Calcic sulphate.— CaSO^. (Sulphate of lime. CaO,
SO3.) — ^Digest powdered, crystallized gypsum a long time
with cold water, witli frequent agitation, let the mixture
stand quietly at last, and decant the clear liquid for use.

6. Chlorine. — CI. — Nearly fill a flask with manganic
binoxide in pieces about as big as peas, and then add so
much common, concentrated hydrochloric acid, that about
half the oxide will be immersed in it. Conduct the gas,
by a glass tube passing through the cork with which the
mouth of the flask is closed, through a cylinder or wash-
bottle containing concentrated sulphuric acid. The evo-

^ 7. KEAGENTS. 15

lution of tlic chlorine begins at common temperatures, but
a little heat must be applied after a time.

7. Cobaltic nitrate. — Co (NO J. _,,— Dissolve the salt in
10 parts of water.

8. Cochineal solution* — Boil cochineal with water.
The solution will keep better if about half its volume of
alcohol is added to it.

9. «.— Cupric acetate.— Cu (CJIgOJCuO. (Acetate
of copper. Verdigris. 2CuC),CJl303.) — To prepare the
solution of this salt for w^ashing the precipitate of baric
sulphate, dissolve the commercial salt in water contain-
ing a little acetic acid, add 2 drops of sulphuric acid, if
this acid is not already present, then a few drops of baric
chloride until the liquid gives a faint reaction for barium,
boil a short time, and filter. The solution should be suffi-
ciently concentrated to deposit crystals on cooling. Use
the supernatant saturated solution.

^. Cupric sulphate. — CuSO^. (Sulphate of copper.
CuO,S03.) — This should be recrystallized once or twice.

10. f urcuma-paper. — Turmeric-paper. — Digest pul-
verized curcuma root with 6 parts of weak alcohol, color
slips of unsized paper with the yellow extract, and dry
them.

11. Ether.— C,H,„0. (C,RO.)— Tliis is sufficiently
pure as obtained of the druggist.

12. a.— Ferric chloride.— Fe^Clg (Perchlorideofiron.
Fe^Clg.) — Its solution should give a permanent precipi-
tate with a drop or two of ammonic hydrate ; it should
give no blue color witli potassic ferricyanide. Dissolve in
20 parts of water.

b. Ferric oxide. — Fe.O.^. (Sesquioxide of iron.) — This
is also known as colcothar.

c. Ferric nitrate.— Fe(N03) 3. (Nitrate of sesquiox-
ide of iron. Fe,0 3,31^0 ^.)— Dissolve iron in nitric acid,

16 § 13. IlEAGENTS.

evaporate the solution to expel excess of acid, and dis-
solve the residue in 10 parts of water.

d. Ferrous chloride. — FeCl^. (Protocliloride of iron.
FeCl.) — Dissolve j)ianoforte wire in concentrated hydro-
chloric acid ; the solution should be made as it is wanted.

6. Ferrous sulphide.— FeS. (Sulphide of iron,)— Get
the fused sulphide of the druggists.

13* Hydrogen. — H. — This is made by the action of di-
lute sulphuric acid on granulated zinc. To purify the gas
conduct it through a TJ tube, or a calcic-chloride cylinder,
containing freshly ignited charcoal, and in order to dry
it, through another cylinder containing calcic chloride.

14. Indigo solution. — This may be prepared by treat-
ing 1 part of finely powdered indigo with 5 parts of
fuming sulphuric acid 48 hours in the cold, and pouring
the mixture into 20 parts of cold water.

15. Iodine. — I. — This needs no testing.

16. a. — Iron Turnings. — These should be clean and
free from grease.

h. Iron wire. — Get the finest pianoforte wire, free from
inist.

17. a. — Lead-paper. — Soak slips of unsized paper in a
solution of plumbic acetate, dry, and keep in a well stop-
i^ered bottle.

h. Litmus-paper (blue). — Digest litmus with G parts of
water, filter, divide half of the filtrate into two equal
parts and carefully saturate the free alkali in one of these
parts with sulphuric acid, until the liquid has taken a red
color that docs not disappear after standing a few min-
utes ; add the other part to this, color strips of unsized
paper in the blue liquid, dry them, and keep in a dark
place. The strips should have a blue color.

c. Litmus-paper (red). — Add sulphuric acid to the
other half of the extract of the litmus until a permanent

§ 18. HE AGENTS. 17

red color is just obtained ; color 'slips of unsized paper in
this solution, dry them, and keep in a dark place. The
strips should have a distinct red color.

18. a. — Magnesia (calcined).— MgO. — This should be
freshly ignited before being used.

h. Magnesia mixture. — ^Mix together 1 part of mng-
nesic sulphate, MgSO^, 1 of amnionic .-chloride, 4 of am-
monic hydrate, and 8 of water; let the mixture stand
several days in a moderately warm j)lace, and decant the
clear solution for use.

19t Malt. — Get good brewer's malt.

20. Manganic binoxide. — MnO„. — The commercial, na-
tive, crystallized hmoxide of manganese is generally suf-
ficiently pure.

21. a.— Mercuric nitrate.— Hg (NO 3)^. (Nitrate of

mercury. HgO,N05.) — Dissolve mercury in its own
w^eight of nitric acid (Sp. Gr.=1.4), heat the mixture to-
wards the close of the operation, and, finally, add to it
twice its bulk of water.

h, Mercurous nitrate.— Hg2(N03)2. — (Subnitratc of
mercury. Hg^O, NO^.) — Pour 1 part of pure nitric acid
(Sp. Gr.=1.2) over 1 part of mercury, let stand 24 hours
in a cool place, separate the crystals from the undissolved
mercury and the mother-liquor, dissolve them in water
mixed with ^1^^ of nitric acid, by trituration in a mortar,
filter, and keep the solution in a bottle with metallic mer-
cury covering the bottom.

MicroCOSmic salt. — ^qqsocHg ammonic phospJiate.

Milk of lime. — See calcic hydrate.

22* Oxygen. — O. — Mix together in a mortar 100 grms.
of potassic chlorate and 0.1 grm. of ferric oxide, half fill
a retort with the mixture, and heat over a coal fire, at first
gently. As soon as the contents of the retort are partly
fused, mix them together by gentle iagitation. Collect

18 § 23. KE AGENTS.

the gas in the gasometer ; for use, conduct it from the
gasometer through a solution of caustic potash (Sp. Gr.=
1.27) in a Liebig's potassa-bulb, then through a U tube
containing pumice-stone soaked in sulphuric acid, and
finally through a tube containing calcic chloride.

Phosphorus salt. — See sodic ammonic phosphate.

23. Platinic chloride.— PtCl^. (Bichloride of plat-
inum. PtCl^.) — Its solution, evaporated to dryness on
the water-bath, should leave a residue entirely soluble in
alcohol.

Precipitates and solutions containing platinum should
be thrown into a bottle containing a solution of ammonic
chloride. When a sufficient quantity of the precipitate
has accumulated, separate it from the liquid by filtration,
wash, dry, and ignite it strongly. Exhaust the residue
thoroughly with hot nitric acid, wash the insoluble part
in water, dissolve in aqua regia with the aid of a gentle
heat, adding fresh portions of nitric acid until the plat-
inum is completely dissolved, evaporate the solution on
the water-bath, with the addition of hydrochloric acid,
and dissolve the semi-fluid residue in 10 parts of water.

24. a.— Plumbic acetate.— Pb (CJIgOJ^. (Acetate
of lead. PbO, C.JI3O3. PbOA.)— The basic acetate,
Ph {CJI^O^„ 2 PbO, is prepared by treating 120 grms.
of crystallized common acetate (sugar of lead) with 60
grms. of gently ignited, and then finely pulverized plumbic
oxide (litharge), and 400 c.c. of water ; let the mixture
stand some time in a Avarm place with frequent agitation,
and finally filter the liquid for use.

b. Plumbic binoxide. — PbO^.

e. Plumbic oxide. — PbO. IJtharge.

25. a. — Potassic acetate. — KC^HjO,. (Acetate of po-
tassa. KO,C^H303.) — This should be white and free from
cmpyreumatic odor. Dissolve in 5 parts of water.

§ 25. IIEAGEXTS. • 10

h. PotaSSic bisulphate.— KHSO^. (Bisulphate of po-
tasga. K0,H0,S03.)

0. Potassic chromate. — ^K^CrO^. (Chromate of po-
tassa. KOjCrOg.) — This should give no turbidity with
argentic nitrate, after acidification with nitric acid. Make
a cold saturated solution.

d. Potassic chlorate. — KCIO^. (Chlorate of potassa.
K0,C10,.)

e. Potassic dicliromate. — K^Cr^O,. (Bichromate of
potassa. KO,2Cr03.) — This should be recrystallized.
Dissolve it in 12 parts of water.

/. Potassic fcrricyanide.— K3Cy,re. K3Cfdy. (Fer-
ricyanide of potassium. K3Cy,Fe2.) — This should give
no blue color with ferric chloride.

g. Potassic ferrocyanide.— K^Cy^Fe. K.Cfy. (Fer-
rocyanide of potassium. K2Cy3Fe.) — Dissolve in 12 parts
of water.

h. Potassic hydrate.— KHO. (Potassa KO,HO.)—
This should not be changed by ammonic sulphydrate, and
should efiervesce but slightly if at all with hydrochloric acid;
the solution obtained with hydrochloric acid in excess,
when evaporated to dryness should give a residue that is
at least almost completely dissolved by water ; the same
solution should give, at the most, but a very slight reac-
tion for i^hosphoric acid with ammonic molybdate, and
should give but a slight flocculent precipitate with am-
monia in excess, after long standing in a warm place.
Pure potassa prepared from an alchoholic solution of the
hydrate should give none of these reactions. Dissolve in
10 parts of water.

i, Potassic iodide. — KT. (Iodide of potassium.) — This
is sufficiently pure as obtained from the druggists.

Jc. Potassic permanganate. — K^Mn^Og. (Perman-
ganate of potassa. KOjMn^O,.)

20 ' § 26. REAGENTS.

/. Potassic sodic carbonate. — KNaCOg. (Carbonate
of potassa and soda. KO, NaO, 2 CO^.) — Recrystallize
some potassic sodic tartrate, ignite the salt in a silver
dish until completely charred, exhaust the black residue
with water, filter, evaporate the filtrate to dryness in the
silver dish, and keep the salt in a well stoppered bottle ;
when it is fused with a little pure sodic nitrate, and the
residue is dissolved in water and nitric acid, and then am-
monia added, each in slight excess, no flocculent precipi-
tate should appear after long standing in a warm place.

m. Potassic sodic tartrate.— KNaC^H.O^. (Seign-
ette salt. Tartrate of potassa and soda. KO, NaO,
CgH^O,^.) — This should be recrystallized once or twice.
It should give a colorless solution with water.

71. Potassic SUlpllOCyanate.—KCyS. (Sulphocyanide
of potassium. KCy S„.) — Dissolve in 20 parts of water.

26. Quartz, powdered, — SiO„. — Drench red-hot quartz
with cold water, and reduce the friable mass to a very
fine powder.

27. a. — Soda lime. — Na^CaO^. — This should not effer-
vesce much with acid, and, Mhen mixed with pure sugar
and heated to redness, it should evolve no ammonia.

In order to have the reagent perfectly free from nitro-
gen, Lawes and Gilbert found it necessary to mix it
intimately with 1-2 "1^ of sugar or some other non-
nitrogenous substance, and ignite the mixture in a muffle,
then to moisten it, and heat it again gently.

h. Sodic acetate. — NaC^HgO^. (Acetate of soda.
NaO, CJI3O3.) — This should be colorless and have no
empyreumatic odor, and should give no reaction with
ammonic molybdate or baric chloride. Dissolve in 10
parts of Avater.

e. Sodic ammonic phosphate.— NaNHJIPO, Phos-
phorus salt. (Phosphate of soda and ammonia. NaO,

§ 28. IIEAGENTS. 21

KHp,HO, PO^.)— This should, give a colorless bead when
fused on platinum wire.

d. Sodic bisulphite.— HNaS03. (Bisulphite of soda.
NaOjHOjSO,.) — This should give a residue Avhen heated
with sulphuric acid, whose solution is not changed by
hydrosulphuric acid or amnionic molybdate. Dissolve in
10 parts of water.

e. Sodic carbonate. — lNra2C03. (Carbonate of soda.
KaOjCOjj.)- — This should be perfectly white, and the solu-
tion obtained after supersaturation with nitric acid should
give no precipitate nor color with baric chloride, argentic
nitrate, or potassic sulphocyanate, nor any reaction with
ammonic molybdate, nor any insoluble residue of silicic
acid w^hen evaporated to dryness. Dissolve the crystal-
lized salt in 3 parts of water, or the anhydrous salt in 5
parts. Keep some of the ignited salt in the dry form.

/. Sodic hyposulphite.— ^a.SJI^O^. (Hyposulphite
of soda. N"aO,HO,S,0,.)

g* Hydric di sodic phosphate. — Xa^HPO^. (Phosphate
of' soda. 2]SraO,IIO,PO^.)— This should not be made
turbid Avhen heated with ammonia, and the precipitate
produced by argentic nitrate, or baric chloride, should be
dissolved completely and without effervescence by dilute
nitric acid. Dissolve in 10 parts of water.

Ji, Sodic nitrate. — NaNO^. (Nitrate of soda. KaO",
KO^.) — This should give no reaction with argentic nitrate
or baric chloride, nor with sodic carbonate.

28. Starch-paper. — Boil starch with 25 parts of water,
saturate strips of paper with the liquid, and dry them.

Tannin. — See acid^ tannic.

29. Tin.— Sn.— Get the best tinfoil of the druggists,
or pure tin in small sticks.

Turmeric-paper. — See curcuma-paper.

30. Uranic acetate. — (U,0) C,H30,. (Acetate of

22 § 31' llEAGENTS.

uranium. (JJfi^fiJIfi^.) — Heat uranic nitrate until a
small part of the uranic oxide is reduced, digest the
yellowish-red residue with acetic acid, filter the liquid
and set the filtrate aside to crystallize ; the crystals are
composed of uranic acetate, while uranic nitrate remains
in solution.

The solution of the acetate should not be changed by
sulphuretted hydrogen after acidification with hydrochlo-
ric acid, and should give a precipitate with ammonic car-
bonate that is entirely soluble in an excess of the reagent.

31. Urea. — Recrystallize it from its solution in alcohol.

32. Water, distilled. — H^O.— This can be prepared by
the analyst himself, if necessary. Dealers in apparatus
can supply small stills of copper and worms of block-tin,
put together and ready for use. The water* must be
colorless and tasteless, and it should leave no residue
when evaporated in a platinum dish. Ammonic sulphide
should give no color to it, nor should basic plumbic ace-
tate make it turbid, nor should ammonic oxalate or
argentic nitrate make it turbid after long standing.

33. Zinc. — Zn. — This should give no reaction for arsenic
with Marsh's test, and, wlien dissolved in nitric acid with
the aid of heat, it should give no red color with potassic
sulphocyanate. Fresenius recommends that before using
zinc for reducing ferric to ferrous oxide in the estimation
of iron by the permanganate process, it should be tested
by the same process. Dissolve a piece of the zinc in di-
lute sulphuric acid in the small, long-necked flask, as de-
scribed in § 52, 5, and, after the flask is filled with water
and its contents are cold, add a drop of a very dilute so-
lution of potassic permanganate, and at the same time
add another drop to the same volume of pure water, and
stir both mixtures well. The depth of color communica-
ted to both liquids should be precisely the same.

§ 34. DETEEMINATION OF SPECIFIC GRAVITY. 23

CHAPTER II.

ANALYTICAL MANIPULATION.

Determination of Specific Gravity.

34. By the specific gravity of a solid or Jiquid is un-
derstood its weight as compared with the weight of an
equal volume of water.

a. The most obvious method of determining it is to
weigh equal volumes of the substance and of water. This
is easily accomplished in the case of liquids, with the aid
of the so-called specific-gravity bottle or piknometer, an
instrument made of thin glass and provided with an ac-
curately ground stopper ; the stopper is sometimes per-
forated. The weight of the empty bottle is ascertained,
then its weight when completely filled with water, or
filled to a mark on the neck, and finally when filled to
the same extent with the liquid under examination ; be-
fore weighing, in each case, all adhering particles of liquid
should be carefully wiped off with blotting paper ; both
weighings should be made at as nearly the same tempera-
ture as possible, or at about 15° C.,the usual temperature
of the working room. Divide the weight of the liquid
by that of the water^for the specific gravity of the former.

h The specific gravity of liquids is also determined
with great facility, though with less accuracy, by means
of the areometer or hydrometer; this is a glass tube
closed at both ends, considerably enlarged towards one
end, and loaded with mercury to make it take a vertical
position in the liquid, but not with enough to cause it to
sink under the surface. The use of the areometer depends
upon the principle, that the less the specific gravity of a
liquid is, the less its buoyant power. The specific gravi-

a4 § 35. ANALYTICAL MANIPULATION.

ties corresponding to the diiferent depths to which the in-
strument will sink in liquids of different densities, are
marked on a scale in the upper, slender part of the tube.
The temperature of the liquid whose specific gravity is to
be determined with the hydrometer should be as nearly
15° C. as possible.

(?. As there is a fixed relation between the degree of
concentration and the specific gravity of a solution of
any given substance, areometers are constructed, upon
whose scales the amount of the substance in 100 parts of
its solution is given, instead of the specific gravity of a
solution of that j^articular degree of concentration. Thus,
we have alcoholometers for mixtures of alcohol and water,
saccharometers for solutions of sugar, acetometers for so-
lutions of acetic acid, lactometers for milk.

35. a. — To determine the specific gravity of a solid^ we
may Aveigh it first in the air, and then while immersed in
w^ater, and suspended from the arm of the balance by a
fine thread or hair. The difference between these two
weights, divided into the Aveight of the body in the air,
will give its specific gravity.

h. Or, if the substance is in the form of a powder that
is insoluble in water, we may weigh it first by itself in
the specific-gravity bottle, then fill the bottle with water,
as in § 34, r/, and weigh again. The difierence between
the weights of Avater that the bottl^ Avill hold, with and
without the substance in it, Avhich is the Aveight of a a'oI-
ume of water equal to that of the solid substance, divided
into the weight of the substance itself, Avill give its spe-
cific gravity.

c. Or, taking advantage of the fact that a cubic centi-
inetre of water weighs very nearly one gramme at com-
mon temperatures, we may make a rough determination
of the specific gravity by filling a 500 c.c. graduated cyl-
inder exactly up to the 250 c.c. mark, then putting a

§ 36. SOLUTION. 25

weighed quantity of the substance (100 or 200 grms.) in
the cylinder, shaking the mixture well so as to disengage
bubbles of air, and observing the volume occupied by
both the substance and the water ; the increased volume,
which represents that of the substance added, expressed
in cubic centimetres, divided into the weiglit of the sub-
stance taken, expressed in grammes, will nearly equal the
specific gravity.

d. If the substance is soluble in water, some other liquid,
like alcohol or naptha, must be used. Determine the
specific gravity of the substance with reference to this
liquid, by the same rules as above, and then multiply the
result by the specific gravity of the liquid used, with ref-
erence to the common standard, water ; the product will
be the specific gravity of the substance with reference to
the same standard.

e. The specific gravity of a substance may be deter-
mined roughly, but very expeditiously, as, for example,
of potatoes, by putting several samples in a shallow dish
containing a saturated solution of common salt, and add-
ing water with constant stirring, until the buoyant power
of the liquid is diminished to such a degree that half the
samples swim at the surface, and half sink to the bottom;
it can then be assumed, with sufficient accuracy for some
purposes, that the average specific gravity of the article
under examination is the same as that of the solution,
and this can be determined with the aid of the hydrome-
ter (§ 34, h).

SOLUTION.

36. In order that a substance may bo analyzed accord-
ing to the methods described in the following pages, it
must be brought into solution if not already dissolved.
The solvents most commonly used are water, hydrochloric
acid, and nitric acid, for inorganic substances, and water,
2

26 § 36. ANALYTICAL MANIPULATION.

alcohol, and ether, for organic matters. As tlie manner of
making the solntion is described in each case, when spe-
cial directions are necessary, but little need be said on the
subject here. As a general rule, heat increases the sol-
vent power of the dissolving agents to a considerable ex-
tent, and hence it should always be applied, unless the
solution is very easily accomplished without, or unless di-
rections are given to the contrary. Time is often an im-
portant element in effecting solution, and hence long con-
tinued digestion at a moderately high temperature may
be useful, or even necessary. A great excess of strong
acid in a solution to be analyzed often causes much
trouble ; hence, as little acid as possible should be used,
and in case a large quantity has been added to the sub-
stance, it should, in most cases, be removed subsequently
by evaporation almost to dryness.

Unless a substance is readily and completely soluble, it
is essential that it should be as finely divided as j^ossible,
and, to this end, it should be ground to a fine powder in
a porcelain mortar, or, better still, an agate one.

In order to reduce a substance to a sufficiently fine
powder, it is sometimes necessary to levigate it, which
means simply to grind it in the agate mortar with the
addition of water enough to make a thin paste, until no
grittiness can be felt under the pestle, nor any grating
sound heard. Then rinse the contents of the mortar
into an evaporating dish, dry the substance thoroughly
over the water-bath, and mix the dry residue together
carefully by further gi-inding in the mortar.

In making a solution for qtiantitative purposes, when
the loss of even a minute part of the substance would
impair the accuracy of the results obtained, if the mixture
of substance and solvent is to be boiled, or if the sub-
stance is a carbonate, and is to be treated with an acid, it
is best to operate in a flask placed on its side, or with its
mouth loosely stoppered by a small funnel, or in a beaker

§ 37. EVAPORATION. 27

covered with one of the large watch-glasses now so much
used for this purpose. The flask with the funnel in its
mouth is better for the solution of carbonates, since fresh
quantities of acid can be conveniently added from time to
time. When the solution is finished, carefully rinse the
funnel or watch-glass into the flask or beaker.

Heat is most conveniently applied to a mixture of sub-
stance and solvent with the aid of the water-bath, or sand-
bath, in making solutions for quantitative purposes, and
often in qualitative analysis also. When it is necessary
to boil the mixture of substance and solvent for a consid-
erable time, and the solvent is more or less volatile, it
is best to connect the flask with the loii^er end of a Lieb-
ig's condenser ; the vapor of the liquid as it is condensed'
flows back into the flask, and it is unnecessary to renew
the solvent until it is quite saturated. See § 39, c.

EVAPORATION.

37 • A liquid may be evaporated either to get rid of a
superabundance of water, that makes the solution too di-
lute, or to expel an excess of acid, or for the purpose of
weighing what it has in solution. In the first and second
cases, the operation may be performed in porcelain dishes,
unless the solution is strongly alkaline.

a. In the third case, if the quantity of the liquid is
large, it may be evaporated to a small bulk in a porcelain
dish, and then carefully transferred to a platinum dish or
crucible. Or the original solution may be put into the
platinum dish in small quantities at a time ; if, however,
the solution contains free chlorine, or nitric and hydro-
cldoric acids together, it must be evaporated in a porcelain
dish until no more fumes of chlorine are evolved ; the
residue may then be transferred to the platinum vessel,
and the evaporation continued.

When a cpnsiderable quantity of a liquid is to be evap-

28 § 37. ANALYTICAL MANIPULATION.

orated, the operation may be performed at first directly
over the lamp ; but in quantitative work the evaporation
should be completed on the water-bath in all cases ; if the
original quantity of the solution is small, it is better to
conduct the whole evaporation on the water-batli.

If the evaporation is connected with quantitative Avork,
the dish should never be more than three-fourths filled,
and the solution should not be allowed to boil at any time
i» an open vessel; evaporation will, however, proceed
quite rapidly in a flask placed partly on its side, and in
this case gentle boiling may be allowed.

Unless the evaporation is performed in a room set apart
for the work, and entirely free from dust, solutions should
be kept covered with filter-paper during the operation ;
the pnper should be supported by glass rods, or a glass
triangle, laid over the dish in such a manner that it cannot
como in contact with the liquid ; if the solution is strong-
ly acid, the paper should have been well washed with
acid, as directed for washing fdters § 39, a ; otherwise,
drops of acid, that have condensed on the glass rods
and come in contact with the paper, may fall back into
the liquid and carry with them inorganic substances that
were dissolved out of tlic paper.

To prevent the salts in solution from being deposited
on the sides of the dish above the liquid, and even over
the edge, smear the rim of the dish, just below the edge
on the inside, with the thinnest possible coat of tallow.
Or, fit the dish in a little jacket of fire-clay, in such a
manner that the part of it above the liquid shall be kept
very hot. Or, turn the crucible on its side, and apply
the flame of the lamp just above the surface of the liquid.

h. When, as is often tlie case in agricultural analysis,
potassa or soda is to bo estimated in a solution containing
a large quantity of anunoniacal salts, and from which
these salts are to be removed by evaporation to dryness
and ignition, Fresenius recommends to evaporate the so-

§ 38. PRECIPITATION. 29

lution to dryness in a porcelain dish on the water-bath,
dry the residue thoroughly at a temperature a little above
100° C, transfer it to another dish with the aid of a
spatula, rinse the porcelain dish with a little water into
the crucible in which tlie residue is to be finally ignited,
evaporate these washings to dryness, then ignite the dry
residue, obtained above, in small portions at a time, and
finally rinse the dish that contained it into the crucible,
with the aid of a little finely powdered ammonic chloride,
and ignite again. The dish with the residue should be
kept in the desiccator while waiting for the ignition.

PRECIPITATION.

38t Precipitation is usually resorted to in order to sep-
.arate certain substances from others in the same solution,
or simply from the solution itself; it consists in adding
some reagent to the solution, which causes the substance
or substances in question to enter into an insoluble form.
The operation is usually performed in beakers, because,
from these, the i:>recipitate is more easily transferred to
the filter.

Care must be taken not to use too large an excess of
the precipitant, and yet there must be no doubt at all that
enough has been added ; if the precipitate does not settle
speedily, so that the efiect of the addition of a fcAV more
drops of the reagent can be observed, a small portion of
the mixture should be throw^n on the same filter that is
finally to receive the whole of the j^recipitate, and the
necessary test can be applied to the filtrate ; this small
portion that has been separated from the main part of the
liquid should then be mixed with it again, before more of
the precipitant is added.

The solution and the reagent should always be well
mixed by stirring, and, in most cases, the solution should
be so dilute that, when the precipitate settles, it will not

30 § 38. AXALYTICAL MANIPULATIOX.

occupy more than one-third or one-fourth the space taken
up by the liquid above it ; and, moreover, for convenience
in filtration, the beaker should not be more than two-
thirds or three-fourths filled by the mixture.

A few precipitates may be filtered out at once, in quan-
titative analysis, but in most cases digestion in a warm
2:)]ace for a longer or shorter time, is required. The beak-
er should be carefully covered during the digestion, so
that no particle of dust can get in, and the operation is
most conveniently performed on the sand-bath.

When about to transfer the contents of the beaker to
the filter, smear a very little tallow under the lip of the
former, wet a glass rod in the liquid, and hold tiiis wet
rod against the lip of the beaker in such a manner that
the liquid will run down the rod and against one side of
the filter.

Of course every particle of the precipitate must be
transferred to the filter if the two are to be weighed
together, with or without ignition. Most of the preci-
pitate can be rinsed out of the beaker by means of
the jet from the washing-bottle ; if any particles re-
main adhering to the glass, they may be loosened w^ith
a stiff feather ; or, when the precipitate is to be ignited
before being weighed, a quarter or a half of a filter, of
the same size and kind as that in the funnel, may
be moistened slightly and rubbed over the sides and bot-
tom of the beaker with the aid of the glass rod, or of
glass-pointed pincettes, and then transferred to the filter,
with most of the remainder of the precipitate adhering
to it ; a little subsequent rinsing with the Avash-bottle
will leave the beaker thoroughly cleansed ; or the precipi-
tate that adheres obstinately to the sides of the beaker
may be dissolved in very dilute acid, and re-precipitated
on neutralization of the acid with ammonia or soda, and
the addition of a little more of the precipitant. If the
second method of cleaning the beaker is followed, remem-

§ 39. FILTRATION. 31

ber to subtract the weight of I'l, or 1' 1^ filter-ash from
the weight of the ignited residue instead of 1 as usual.

• FILTRATION.

39. a. — Solid particles are separated from the liquids
Avith which they may be mixed by the process of filtra-
tion, referred to in the preceding paragraph, which con-
sists simply in passing the liquid through porous unsized
paper, that intercepts the solid.

. Paper, already cut in convenient sizes, can be had of
apparatus dealers. For quantitative purposes, filters of
Swedish paper should be used, or common white filters
that have been washed in dilute acid ; to wash filters,
pour over them, in layers of moderate thickness in a large
evaporating dish, a mixture of one part of hydrochloric
acid and nine parts of water ; digest for several hours at
a moderate temperature, wash with distilled water by de-
cantation until the washings no longer redden litmus,
transfer the bunches of paper to blotting paper, and leave
them undisturbed until the filters can be separated from
each other without being torn. These washed filters
are more suitable for filtration by Bunsen's process than
those of Swedish paper, as they are stronger and less lia-
ble to be torn.

To make the filter, fold the circular piece of paper twice
in directions at right angles to each other, and through
the centre ; open the quadrant thus formed in such a man-
ner as to make a conical cavity, put it in a glass funnel,
which should be at least 3-5 millimetres larger than the
filter, wet the latter with a httle water from the washing-
bottle, and press it closely agamst the glass throughout
with the finger.

The filter should never be filled Avith the liquid to
within less than 6 mm. of the top, and should not ordi-
narily be much more than half filled with the precipitate
when the liquid has drained off.

32 § 39. ANALYTICAL MANIPULATION.

Most liquids may be filtered much more rapidly when
hot, and many precipitates are much less liable to pass
through the filter, or to choke it up, -when formed in nearly
boiling hot solutions by hot reagents.

When possible, it is best to let the solid matter settle
to the bottom of the vessel containing the mixture of
liquid and precipitate, then to decant as much as possible
of the clear, supernatant liquid on the filter, pour fresh
distilled Avater over the contents of the beaker, stir well,
and perhaps heat almost to boiling, let the precipitate set-
tle, and decant the liquid again ; this may be repeated 'a
number of times before putting the solid substance on the
filter.

If the precipitate is to be dissolved without weighing
or ignition, it is generally best to wash it altogether by
decantation, and then to pour the solvent over the filter
through which the decanted liquid was passed, and collect
it in the beaker containing the main portion of the 'w'^shed
precipitate ; the precipitate may then be digested with
the reagent if necessary, and, afterwards^ the filter well
washed out with water, that is added to the solution just
made ; in this way we may avoid any considerable dilu-
tion of the solvent before it has had time to act on the
substance to be dissolved. If the solvent is one that, in
its concentrated state, would attack the paper, it may be
230ured at once over the precipitate in the beaker, while
another portion may be diluted somewhat, and passed re-
peatedly through the filter, to take up the small quantity
of the substance on that.

The thorough washing of precipitates and residues,
that is so essential in quantitative analysis, and is often
not unimportant in qualitative work, may sometimes be
greatly facilitated by this process of decantation, particu-
larly if the solid is one that settles readily ; but if Bun-
sen's process of filtration is followed, decantation may be
dispensed with.

§ 39. filtration; bunsen's process. 33

In washing precipitates on the filter, the washing-bottle
is an indispensable aid. This consists simply of a flask
of a capacity of 150-1000 c.c, according to the purpose
for which it is to be used, closed by a good cork that is
pierced Avith two holes ; through one of these holes passes
a glass tube, 8 or 10 cm. long, that extends just beyond
the coik on tlie inside, and, outside, is bent at an angle
of about 110° ; the tube that passes through the other
hole extends nearly to the bottom of the flask, and, out-
side, is bent at an angle of about 70°, and drawn out to a
small jet at the end; water in the flask is forced out at
this jet on blowing air in at the mouth of the shorter
tube.

Each portion of water with which a precipitate on the
Clter is washed should be allowed to pass through com-
pletely before another is added, and the prccii^itate should
be stirred up as much as possible by the jet from the
wash-bottle witli .each fresh addition.

Insoluble residues and precipitates must be washed,
particularly in quantitative operations, as long as the wash-
water carries oflT any notable quantity of matters in solu-
tion ; the washings are tested by evaporating a drop to
dryness on platinum foil, to see if any residue is left, or
by a chemical test, as, for example, when washing a pre-
cipitate of baric sulphate that was formed by adding
baric chloride to a solution of a sulphate; r.s long as any
of the soluble chloride remains in the pores of the filter,
or adheres to the precipitate, and is taken up by the
Vv'ater, the washings Avill give the usual reaction for
clilorine with argentic nitrate (§ 63).

When the contents of the filter are to be weighed or
ignited, dry the whole together in the drying-chamber or
air-bath, with the funnel well covered with filter paper.

K A metliod lately devised by Bunsen {Annalen dcr
Chemie, 148, 270. American Jonrnal of Science and
Art, 2d Series, 47, 321) for iiicreasing the rapidity of fil-

84 § 39. ANALYTICAL MANIPULATION.

tration, and of the washing of precipitates, promises to be
very useful.

He supports the filter by a hollow cone of thin plat-
inum foil in the throat of the funnel, and then rarefies
the air in the funnel-tube; the excess of pressure on the
liquid in the filter causes it to flow througli very rapidly,
while there is no danger of tearing the paper.

To make the platinum funnel, a cast of the glass funnel
must first be taken. Select a funnel with perfectly smooth
and straight sides, ai)d opening at an angle of 60°, fit in
it a piece of oiled Avriting paper in such a manner that it
shall touch the glass everywhere, like an ordinary well-
fitted filter, and fasten the paper in place with two or
three drops of sealing-wax around the rim. Half fill the fun-
nel then with gypsum paste, into which, before it hardens,
a plug of wood is inserted, to serve as a handle. When the
gypsum cone has hardened, remove it from the funnel, oil
the paper again, and plunge it, with the paper still adher-
ing, into a large porcelain crucible filled with another por-
tion of gypsum paste ; v>^hen tliis mould has hardened,
take the cone out and rub ofi* the paper Avith the fingers.
g Now, cut out a piece of thin plat-

inum foil Aveighing about 0.154 grm.,
of the precise shape and size repre-
sented in the adjoining figure, with a
slit running from h to a^ the centre
of the circle of Avhich the arc, c c c?,
forms a part ; ignite it in the flame of
the lamp to make it perfectly flex-
ible, lay the gypsum cone on it so that the apex
of the cone shall coincide with a^ bring up the edge, a h c7,
and press it well against the cone, and then do the same
with the edge, ab c ; after fitting the foil to the cone as
l^erfectly as possible Avith the fingers, put the Avhole in the
mould in the crucible, and revolve the cone back and
forth until the platinum has taken the exact shape of the

§ 39. filtration; bunsen's process. 35

plaster casts, and retains its form when removed from the
mould ; if found necessary, it may be ignited once more
and shaped in the mould with the cone. It may be sol-
dered at its upper edge by a grain of gold and borax, so
that it will be less liable to get out of shape, but this is
not necessary. If properly made, the light should not be
visible through tlie point of this platinum funnel when it
is held before the window.

With the platinum funnel in the throat of the glass
funnel, adjust the paper filter, which may be much small-
er than would be used in the ordinary way of filtering, in
the usual manner, with special care to secure perfect con-
tact between the filter and the funnel at all points. Con-
nect the tube of the funnel with a large, strong glass
flask, by means of a rubber cork pierced with two holes,
BO that the tube extends about G cm. beyond the cork ;
through the other hole pass a short glass tube so that it
extends just to the lower surface of the cork ; this tube
should be bent once at a right angle outside of the flask ;
it may be connected with a small brass stop-cock by
means of a short rubber tube with a small bore and very
thick walls ; all the rubber tubing used in the apparatus
should be of this kind.

Now, pour the liquid to be filtered on the filter, rarefy
the air in the flask, and keep the former full as long as
any of the liquid remains. The precipitate may be al-
lowed to come within 1 mm. of the edge of the filter.

In washing the precipitate, pour the water from a flask,
fill up to about a centimetre above the rim of the filter,
with care not to disturb the precipitate, and let each por-
tion of water drain off completely before adding a fresh
quantity ; thus the w^ashing may be thoroughly effected
in a Avonderfully short time ; if the vacuum in the flask
is nearly perfect, or the pressure on the filter is nearly an
atmosphere, three or' four washings suflice, even in the
case of precipitates that are the most diflicult to wash.

36 § 39. ANALYTICAL MANIPULATION.

Moreover, tlie precipitate is so completely deprived of its
water, that it may be easily removed from the filter, or
can be ignited at once without further drying.

To ignite the precipitate at once, Bunsen directs to wrap
the filter around it, put the whole in the crucible, set the
latter on its side as usual, apply the heat at the top of
the crucible first, and gradually carry it towards the bot-
tom as the filter is burned.

The rarefaction of the air may be produced in various
ways. The flask may be connected with the upper end
of a water-pipe 30 feet high in such a manner as to make'
a Sprengel's air-pump. Desaga, of Heidelberg, furnish-
es a complete apparatus for this purpose.

Or, an air-tight connection may be made between two
large glass bottles, or demijohns, by means of a long piece
of thick walled rubber tubing ; then put one bottle filled
, with water on a high shelf, while the other is put on the
floor, connect the filtering-flask witli a tube leading just
through the cork of the upper bottle, allow the water to
flow from the upper bottle to the lower one, while pro-
vision is made for the escape of the air from this lower
bottle ; the rarefaction of the air in the filtering-flask will
follow. When all the water has flowed from the upper
to the lower bottle, their relative positions may be re-
versed, the proper connection made between the flltering-
flask and the upper bottle, and the filtration continued.

Or, a small demijohn may be closed by a rubber cork
through which passes a glass tube, connected with a
small brass stop-cock; connect the demijohn with an air-
pump, exhaust the air, close the stop-cock, connect the
demijohn with the filtering-flask, and open the stop-cock
when all is ready for the filtration. In order to prevent
acid fumes or ammonia coming from the filtered liquid
from injuring the stop-cock, a wash-bottle, containing
sodic hydrate or sulphuric acid, may be interposed. (J
M. Crafts.)

§ 39. FILTRATION. 37

For fuller details in regard to this mode of filtration
we refer to the original articles.

c. When several portions of a solvent, such as water,
alcohol, or ether, are to be made to act on a substance,
each portion can be readily separated from the substance
by the following contrivance.

Close the flask with a rubber cork pierced with two
holes ; through one of these pass a short bent tube, like
the shorter tube of the common washing-bottle, and in
the other hole fit a tube which is widened out, funnel-like,
at one end, but not so much as to prevent its being put
into the flask easily ; near the other end, this tube is bent
at an acute angle, and the end is drawn out to a point
and left with a pretty large opening, after the fashion of
the other tube of the washing-bottle ; the long arm of
the tube should reach nearly to the bottom of the flask,
and have a piece of fine linen firmly bound over its mouth.

The substance and the solvent having been digested in
the flask, when the solvent is supposed to be saturated,
and it is desired to replace it by a fresh quantity, force
air into the flask by the shorter tube and the solution will
be expelled, and at least partially filtered on its way
through the muslin ; then, if the end of the longer tube
is inmiersed in a fresh quantity of the solvent, this may
be drawn into the flask by suction at the mouth of the
short tube.

If heat is used, the mouth of the short tube may be
connected with the Ic^wer end of a Liebig's condenser ;
then tlie vapors of the solvent are condensed, and the
liquid flows back into the flask, and the ebullition can be
maintained as long as is desired without the necessity of
adding fresh quantities of the solvent to replace what is
lost by evaporation ; when it does become necessary to
replace this portion of the solvent by a fresh one, the rub-
ber tube that connects the flask with the condenser may
be closed with a clamp, and, the application of heat being

38 § 40. ANALYTICAL MANIPULATION-.

continued, the liquid will be forced out through the mus-
lin filter ; on immersing the open end of the longer tube
in a fresh quantity of the solvent, and removing the lamp,
this liquid will flow in.

The solution may not bo perfectly clarified in passing
through the linen filter, in which case it will have to be
filtered again through paper.

To efiect more perfect filtration, a thick mat of gun-
cotton may be bound over the linen ; this layer of cotton
should not be anywhere less than 14 mm. thick.

WEIGHING OF RESIDUES AND PRECIPITATES.

40. When it is possible, residues or precipitates are ig-
nited before being weighed.

This ignition may be performed in two ways.

a. If the substance is not altered in its chemical com-
position by contact with burning organic matter, or at
the somewhat high temperature that is sometimes neces-
sary to efiect the complete incineration of the filter, roll
the well-dried filter together around the precipitate, put
the whole in the previously ignited and weighed crucible,
cover and heat, at first very gently ; when the filter is
completely charred and no more smoke is given off*, turn
the crucible on its side, lay the cover partly on the edge
of the crucible and partly on the triangle, and heat the
contents of the crucible until the ash is quite Avhite.

J). If the filter may not be burned in direct contact
with the preciiiitate, crush and work it gently between
the fingers over a sheet of glazed paper, to loosen the pre-
cipitate as much as possible, place the crucible on the
glazed paper, and empty the contents of the filter into it.
Put the crucible on the porcelain plate belonging to the
Bunsen's burner, open the filter on another piece of
glazed paper, fold its edges up so as to make a little tray,
with a soft feather carefully brush into this tray any

§ 40. WEIGHING OF RESIDUES AXD PRECIPITATES. 39

particles of the precipitate that may have fallen on tlie
first piece of paper, roll the filter up, enclose it in a short
spiral on one end of a platinum wire that was weighed
with the crucible, hold it over the crucible, and set fire to
it ; by applying tlie charred filter to the flame of the
lamp two or three times it may be almost completely in-
cinerated ; finally, either let the ash and the wire drop
into the crucible and ignite the whole four or five minutes,
or until the ash is white, or, in case the filter-ash must be
kept entirely separate from the precipitate, let the two
drop into the hollow lid of the crucible, and ignite the
precipitate and ash separately.

The glazed paper used above should be of a light color
if the j)recipitate is dark-colored, and vice versa, and the
whole operation should be performed in a place free from
currents of air.

c. If the quantity of the pi-ecipitate is very small, and
yet is of such a nature as to be partly reduced to a lower
degree of oxidation if ignited with the filter, the ignition
may be performed as in a ; when it is completed, put a
piece of diy amnionic nitrate in the crucible, cover well,
and ignite again, but very gently at first.

Ferric oxide or baric sulpliate may be ignited in this
way when nothing better can be done.

Sometimes, when a portion of the filter is very difficult
to incinerate completely, the combustion may be facilita-
ted by adding a little animonic nitrate as above.

After weighing, subtract the weight of the filter-ash,
which has been determined once for all for the particular
kind and lot of paper and size of filter used, by the incin-
eration of half a dozen or a dozen together, and dividnig
the total weight of the ash thus obtained by the number
of filters burned.

d. If the substance to be weighed cannot be ignited, a
filter should be previously thoroughly dried in the steam
or air-bath at the same temperature to which it is after-

40 § 41. ANALYTICAL MANIPULATION.

wards to be exposed with the precipitate, and weighed,
either between two watch-glasses with ground edges and
fitting well together, or in a stoppered glass tube ; after
careful drying with the precipitate, it is again weighed in
the same manner. It should then bo dried an hour
longer and weighed again, and this should be repeated
until a constant weight is obtained. Swedish filter-paper
or Avashed filters should always be used in this operation.

c. The substance that has been dried or ignited, and is
to be weighed, should always be allowed to cool under a
bell-glass over concentrated sulphuric acid, or in the des-'
iccator more commonly used for this purpose ; this desic-
cator consists simply of a short and wide glass cylinder,
with a ground edge upon which a ground glass plate will
fit closely, particularly if the edge is smeared with a lit.l3
tallow.

The pair of watch-glasses containing the dried filter,
or the crucible with the ignited precipitate, rests on a tri-
angle in the cylinder over fused calcic chloride, with
which the bottom is covered.

No object^ should be weighed until it is entirely cold.

/. Platinum vessels, after having been heated by gas,
should be rubbed with a little sand on the moistened fin-
ger. The sand should be fine, and all its grains should
be rounded. The crucible should also be cleaned from
time to time by fusing a little potassic bisulphate in it.
The crucible should be supported over the lamp on stout
platinum wire, which is stretched from side to side of a
larger iron-wire triangle, in such a manner as to make a
second triangle inside of, and about C mm. smaller than,
the iron triangle.

MEASURING AND DIVIDING SOLUTIONS.

41. For these purposes graduated pipettes and cylin-
ders, and 'I,, ' !„, and 1 litre flasks are used.

§ 41. MEASURING AND DIVIDING SOLUTIONS. 41

The analyst slioukl test tlie correctness of the gradua-
tion of his instruments before using them, by comparing
them with each other; the '1^ litre flask should require
just as much water to fill it twice up to the mark on the
neck as is required to fill the ' \^ litre flask once up to the
mark on its neck. In the same way the ' |, litre flask
should be compared with the 1 litre flask, and these with
the graduated cylinders, and the pipettes with each other
and the graduated cylinders.

When a certain quantity of any standard or titrated
solution is to be measured out with a pipette or flask, the
instrument should either be dry on the inside, or it should
be rinsed out with a little of the solution to be measured,
and the last drop of the solution that remains in the point
of the pipette should either always be allowed to remain
there, or it should always be blown out into the vessel
containing the measured solution ; the same course should
be followed in testing the graduation of the pipettes.

To read ofl" the lieight of a solution in a burette or
other graduated instrument, be sure, first, that it is in a
vertical position, so that the surface of the liquid in it
will be horizontal ; then place the cylinder between the
eye and a brightly illuminated white wall, and read the
height of the lower surface of the dark zone that is read-
ily seen under these circumstances just beneath the sur-
face, while the eye is in the same horizontal plane.

In filling a Mohr's burette, fill up to above the zero
mark with the solution, and quickly oj)en wide the clamp
for a moment so that the rubber tube and the glass tube
below the clamp will be completely filled ; then open the
clamp a little and allow the liquid to flow out, drop by
drop, until the dark zone, mentioned above, reaches the
zero mark.

The temperature of all measured liquids should be as
nearly 15° C. as possible.

When the quantity of a solution to be divided is not

42 § 4,2. ANALYTICAL MAI^-IPULATIOX.

too large, the division may be more accurately made by
weighing than by measuring. Get the weight first of the
whole amount of tlie liquid, in a small flask, pour out
about the quantity desired for a particular analysis, and
weigh the flask again with the remainder of the liquid ;
pour out another quantity and weigh again, and so on
until the division is completed.

For this purpose, a fl:\sk with a little spout, attached
just below Avhere the neck widens out into the body, will
be found very convenient.

CxVLCULATION OF RESULTS.

42t The results of an analysis are usually calculated so
as to give the per cent composition of the compound
analyzed.

If the substance determined is weighed or estimated in
the form in which it existed in the compound, and it was
determined in the undivided solution of the same, noth-
ing remains to be done but to estimate the percentage by
a simple rule-of-three calculation, in which the amount
taken for analysis is the first term, the amount of the sub-
stance found the second, and 100 the third.

If the substance was determined in a fractional part of
the solution, the same fractional part of the weight of the
compound taken for analysis must be made the first term
of the proportion ; or the amount of the substance found
may be estimated for the whole amount of the original
solution by multiplication by the proper number, and this
product is then made the second term of the proportion,
the first term being the weight of the whole amount taken
for analysis.

In gravimetrical analysis the substance is usually
weighed in the form of some insoluble compound that
did not exist at all in the compound analyzed, and the
amount of the substance in the weight that was found of
this insoluble compound must first ba calculated.

§ 42. calOulatiox of kesults. 43

This may be effected by a rule-of-three calculation also,
in whicii the molecular weight cf the insoluble sub-
stance is made the first term, the weight of the substance
sought in a molecule of the insoluble substance the second,
and the weight of the insoluble compound found the third.

For example, in a determination of sulphuric acid, SO3,
1.13 grm. of baric sulphate was found; then we have

BaSO, : SO3 = BaSO, : SO3

233 : 80 = 1.13 : 0.3879 grm.

The same result can be more expeditiously obtained,
however, with the aid of Table III, where for each special
case a part of this calculation has already been perform-
ed, namely, the division of the second term by the first ;
nothing is left to be done, therefore, but to multiply the
weight of the insoluble compound found, whose name U
given in the first column, by the decimal in the second
column against the name of the substance sought in the
third column. In the above-mentioned case we find, on
consulting the table, the proper decimal against tlie
names sulphuric acid and baric sulphate is 0.3433, which
multiplied into 1.13 grm. = 0.3879.

44 8 43. BASES AND ACIDS WITH IlEAGENTS.

CHAPTER III.

BEHAVIOR OF THE MORE COMMON BASES AND ACIDS WITH
REAGENTS, AND THEIR QUANTITATIVE ESTIMATION.

43. The substances for whose qualitative detection or
quantitative estimation directions are given in the follow-
ing pages, are as follows.

1. Inorganic^ basic elements. — Potassium, sodium, bari-
um, calcium, magnesium, aluminium, iron, manganese, zinc,
lead, and copper.

2. Volatile, basic radical. — Ammonium.

3. Acid elements and inorganic acids. — Arsenic, chlo-
rine, iodine, fluorine, sulphur, and sulphuric, phosphoric,
carbonic, silicic, and nitric acids.

4. Compound, acid radicals. — Cyanogen and ferrocy-
anogen.

5. Organic acids. — Oxalic, acetic, tartaric, citric, malic,
uric, hippuric, lactic, and tannic acids.

6. Indifferent organic substances. — Cellulose, starch,
sugar, gum, albuminoids, urea, fat, and alcohol.

POTASSIUM. K. C9.1

44( — Salts of potassium, with all the acids mentioned
in § 43, except tartaric, are easily soluble in water. The
tartrate is soluble in free alkali or mineral acid, or in
considerable water.

Reactions* — In tolerably concentrated, neutral or
slightly acid solutions of potassic salts, containing hydro-*
chloric acid or a soluble chloride, platinic chloride, PtCI^,
gives a yellow, granular, crystalline precipitate, K,,PtClp,
which is sparingly soluble in water, and nearly insoluble
in alcohol. Its solubility is slightly increased by the

§ 44. POTASSIUM. 45

presence of free hydrochloric acid. No precipitate will
be given by the reagent in a very dilute sohition of the
potassic salt, but if such a solution is evaporated nearly
to dryness with a little platinic chloride, and alcohol is
added to the residue, the yellow double salt remains un-
dissolved.

If a drop of a solution of a potassic salt is evaporated
to dryness in the platinum-wire loop, and the loop with
the residue on it is held at the end of the inner blowpipe
flame, or in the corresponding part of the flame of the
Bunsen gas-burner, a violet color is communicated to the
flame beyond the wire. Viewed through thick blue glass,
this color has a more reddish appearance, but the light is
not entirely absorbed ; the j^resence of sodium, barium,
calcium, and copper, may interfere with this reaction.

In a silicate, this reaction for potassium may be ob-
tained by fusing it, in a fine powder, with pure gypsum,
treating the fused mass with w^ater, filtering, and testing
the filtrate.

Quantitatiye estimation* — Potassium may be deter-
mined as potassic chloride, KCl, potassic sulphate, K^SO^,
or potassic platinic chloride, K^PtClg.

The first two salts are soluble in water, and therefore
cannot be obtained by precipitation ; other metals and
acids being removed from the solution by methods here-
inafter described, the pure salt is then left as a residue on
evaporation to dryness.

a. Determination as potaSSic chlorldC. — The solution
being freed from other metals and acids, evaporate it to
dryness over the water-bath, and ignite the residue in a
well covered platinum crucible, very gently for a consid-
erable time at first, to avoid the decrepitation and conse-
quent loss that might result from too rapid heating;
finally, heat the crucible to a dull red for a short time.
The residue contains 52.41° |, of potassium.

46 § 44. BASES AND ACIDS WITH REAGEJ^TS. .

h. Determination as potassic Sulphate. — The solution
being freed from other metals and from non-volatile acids,
as directed in each special case, evaporate it to dryness
and ignite the residue in a platinum crucible, as directed
for the ignition of potassic chloride, except tliat it may
be more strongly heated at the close of the operation.

If volatile acids, such as hydrochloric, nitric, or acetic,
are present in tlie solution containing the potassium to be
determined, sufficient sulphuric acid must be added before
evaporation to expel them; in order, however, to avoid
the disagreeable operation of expelling a large excess of
sulpliuric acid also, it is well to add but little at first ; the
evidence that enough has been used will be found in the
evolution of abundant white acid fumes towards the close
of the evaporation ; if these fumes do not appear, of
course a little more acid must be added, and the evapora-
tion continued.

After igniting the residue in the j)latinum crucible
gently for a little while, put in a small fragment of well
dried amnionic carbonate, and ignite again while the
crucible is loosely covered, very gently at first, and then
gradually raise the heat to a full red ; repeat this addition
of ammonic carbonate and the subsequent ignition as
lonsr as there is any chanixe in weii^ht.

The ignition with ammonic carbonate facilitates the ex-
pulsion of the second equivalent of sulphuric acid from
the potassic bisulphate, and it should be used in the man-
ner indicated whenever free sulphuric acid was present in
the solution that was evaporated. The residue of potassic
sulphate contains 44.89'' |„ of potassium, or 54.08° |^ of
potassa.

c. The determination of potassium as potassic platinic
chloride depends upon the insolubility of this conqjound
in alcohol.

The solution being freed from all except potq,ssic and
sodic chlorides, and, according to Stohraann, calcic and

§ 44. POTASSIUM. 47

magnesic chlorides also, and highly concentrated, add
platinic chloride in excess, until the liquid has a bright
yellow color, and evaporate the mixture nearly to dryness
over the water-bath, with care not to heat the water quite
to boiling.

Pour alcohol of 84" 1^,, mixed with '|g its volume of
ether, over the residue, let stand several hours in a well
covered vessel, with occasional stirring, transfer the in-
soluble double chloride to a dried and weighed filter,
wash it with alcohol and ether mixed as above directed,
dry at 100° C, and weigh.

If great accuracy is required, evaporate the filtrate
from this first portion of the chloride nearly to dryness,
at a temperature not above 75° C, after addition of some
water and more i^latinic chloride, and some sodic chlo-
ride if but little of this is supposed to be present, and
treat this almost dry residue with the mixture of alcohol
and ether as above ; if a second quantity of insoluble
chloride is thus obtained, collect it on a filter, wash, dry,
and weigh it, and add the amount so found to the first
quantity.

The salt contains 16"| „ of potassium.

If the quantity of the precipitate is quite small, less
than 0.03 grm. or thereabouts, it is better to collect it on
a small filter, incinerate the filter, add a little pure oxalic
acid to the cooled residue, cover the crucible, and ignite
again gently at first, and more strongly afterwards ; after
this ignition nothing but platinum and potassic chloride
remains ; dissolve out the salt by washing the residue
with water until the washings give no turbidity with ar-
gentic nitrate, and dry, ignite, and weigh the platinum.

d. In some cases, as in the analysis of wood-ashes,
potassium or potassa may be determined by a volumetric
process, which consists in ascertaining' the amount of a
solution of sulphuric acid of known sti-ength, that is re-

48 § 45. BASES AND ACIDS WITH llEAGENTS.

quired to combine with it and form a salt which is neutral
to test-papers (§ 45).

PREPARATION OF THE STANDARD ACID AND ALKALINE
SOLUTIONS.

45. a. — Sulphuric acid. — To about 1100 c.c. of water
add nearly 68 grms. of concentrated sulphuric acid, mix
the whole well together, let the mixture cuol to the tem-
perature of the working room, and then estimate sulphu-
ric acid with baric chloride (§ 59) in two or three portions
of 20 c.c. each, with the utmost care ; having in this w^ay
determined the strength of the solution, dilute it sq. tliat
one litre shall contain exactly one equivalent of the acid
expressed in grammes, or 40 grms. Supposing that the
mean of three satisfactory determinations, as above, gives
0.84 grm. of sulphuric acid in 20 c.c. : then we learn from
the proportions, 20 : 0.84 = 1000 : 42, and 40 : 42 =
1000 : 1050, that 50 c.c. of water must be added to one
litre of the acid that we have made, in order that it shall
be of tlie proper strength ; to effect this farther dilution,
measure out 1000 c.c. of tlie acid in the litre flask, pour
it without any loss into the bottle in which it is to be
kept, rinse the walls of the flask with exactly 50 c.c. of
distilled Avater, pour this water likewise into the same
bottle without loss, and mix the acid and rinsings together
well; finally pour about halt* the contents of the bottle
into the flask, rinse off the walls of the flask with the
liquid, and pour it back into the bottle.

The bottle containing this standard acid should be kept
well stoppered ; each time that a portion is to be taken
out, the contents of the bottle should be shaken up in
such a manner as to rinse down the water that may have
evaporated in the space above the liquid and condensed on
the glass. {Freseniiis. Quantitative Chemlsche Analyse.)

Since 40 is the equivalent of sulphuric anhydride, SO3,

§ 45. PREPARATION OF THE STANDARD SOLUTIONS. 49

and this standard or normal solution contains an equiva-
lent of the anhydride expressed in grammes, in a litre,
( = 1000 cubic centimetres) it contains, then, an equivalent,
expressed in milligrammes, in one cubic centimetre = 40
mgr. or 0.04 grm. The quantity of acid in one cubic centi-
metre will combine with exactly one equivalent of potassic
oxide or potassa, K^O, expressed in milligrammes, = 47.1
mgr. or 0.0471 grm., and form a salt whose solution is
neutral to test-papers ; in a like manner, the acid in one
cubic centimetre of the standard solution will combine
with or neutralize one equivalent of sodic oxide or soda,
Na^O, expressed in milligrammes = 31 mgr. or 0.031 grm.,
or with one equivalent of ammonic oxide, (ISTHJ^O, = 26
mgr. or 0.026 grm.

The neutrality of the solution may be determined by
its effect on paper that has been colored by litmus, or by
adding a small quantity of a solution of litmus, or of
cochineal or curcuma root. Litmus is colored blue by
free alkali, and red by free acid ; cochineal under the same
circumstances is colored purple and light reddish-yellow,
while curcuma or turmeric is colored brown by free alkali,
and yellow by acids.

If, then, to a solution containing any one of the alkalies
just mentioned, either in a free state or combined with
the weak carbonic acid, we add a little cochineal solution,
and then the standard acid from a burette or a graduated
pipette, with constant stirring, until the purple color sud-
denly disappears, and a reddish-yellow one takes its place,
that remains permanent throughout the whole liquid, we
may know that, for each cubic centimetre of acid added,
there were 0.0471 grm. of K,0, or 0.031 of Na^O, or 0.026
of (NHJP in the solution; the whole amount of the al-
kali in the quantity of its solution taken for analysis will
be given by the product of the number of cubic centime-
tres of acid required, into the corresponding equivalent
3

50 § 45. BASES AISTD ACIDS WITH REAGE:NTS.

of the alkali, expressed in milligrammes or fractions of a
gramme as above.

h. Standard oxalic acid. — Put G3 grms. of pure crys-
tallized oxalic acid in a litre flask, fill the flask up to
about two-thirds with water, and, after the acid is entirely
dissolved, add more water until it rises nearly to the mark
on the neck of the flask ; bring the water to a tempera-
ture of 15° C, and then, holding the flask by the rim, so
that it will take a vertical position, carefully add water
up to the mark on the neck. Mix the whole well together
by shaking, transfer the liquid to a well stoppered bottl'e,
and keep it in a dark place. As 63 is the equivalent of
crystallized oxalic acid, expressed in grammes, this nor-
mal solution contains, like the standard sulphuric acid,
one equivalent of the acid expressed in milligrammes,
=63 mgr. or 0.063 grm., in one cubic centimetre.

c. A standard soda solution is often wanted in connec-
tion with the use of the standard acid, and for other pur-
poses, and its preparation may be described here.

It is made of such a strength that one cubic centimetre
of it will be exactly neutralized by one cubic centimetre
of the standard acid, or will contain 0.031 grm. of sodic
oxide, Na^O.

To prepare it, put 5 c.c. of the standard acid in a small
flask with a very little cochineal solution, and then add a
diluted solution of sodic hydrate, of which a considerable
quantity has been previously made, from a 5 c.c. pipette
graduated into twentieths of a cubic centimetre, very
slowly and with constant shaking of the flask, until the
reddish-yellow color is just changed to purple ; suppose
that 2 c.c. have to be added ; then evidently 3 c.c. of wa-
ter must be added to 2 c.c. of the soda solution, in order
to make 5 c.c. of the latter that shall exactly neutralize
5 c.c. of the standard acid ; or ^^^""" = the amount of
water to be added to one litre of the sodic solution, to

§ 46. SODIUM. 51

make it of the normal strength. When the solution has
been prepared according to these directions, and the water
and alkali are well mixed, it should be tested, to be sure
that the equality between the acid and the alkaline solution
is perfect. Keep the solution in a bottle closed with a
cork, through which j^asses a calcic-chloride tube that is
stopped at its lower end with a plug of cotton and then
filled with soda-lime ; by this arrangement; the free ex-
pansion of the air in the upper part of the bottle with
changes of temperature is permitted, while no carbonic
acid can enter ; ifc is well to bend the slender part of the
calcic-chloride tube at a right angle just above the cork,
so that no soda-lime can possibly fall into the bottle, and
to fill the burette by means of a small siphon passing
through the cork to the bottom of the bottle, the longer
arm of which may be closed at the end by a clamp on a
rubber tube.

To 100 c.c. of this solution add 900 c.c. of water, mak-
ing both measurements with the utmost care, mix well,
and test this solution with the standard acid ; 1 c.c. of
the latter should require exactly 10 c.c. of the former to
neutralize it ; keep this solution in the same manner as de-
scribed for the other standard soda solution, and labeled,
^ Ijo standard soda solution.

SODIUM. Na. 23.

46. Salts of sodium, with all the acids named in § 43,
are soluble in water. The double chloride of sodium and
platinum is also soluble in both water and alcohol.

When this solution is very slowly evaporated to dry-
ness, slender, rosy, prismatic crystals are formed, while
the crystals of the corresponding potassium salt are octa-
hedral and granular.

Reactions. — ^When a drop of a solution of a salt of so-
dium is evaporated to dryness in the platinum-wire loop,

52 § 46. BASES A^^D ACIDS AVITH REAGENTS.

and the loop is then held at the end of the inner blow-
pipe flame, or in the corresponding part of the flame of a
Bunsen's gas-burner, a yellow color is commuuicated to
the flame beyond the wire.

These yellow rays are completely absorbed by blue
glass of suflicient thickness. This test for sodium is very
delicate, and is not masked by even a considerable pro-
portion of any other metal, except copper and calcium.
The presence of a very large proportion of potassium
may conceal the sodium reaction. In that case, green glass
will absorb the violet rays of the potassium flame, but
will not aflect the colored rays produced by the sodium.

Quantitative estimation. — a. Sodium, like potassium,
may be weighed as chloride or as sulphate, on evaporat-
ing the solution to dryness, from which all other acids
except hydrochloric or sulphuric have been removed by
the methods described in each special case.

The operations of evaporation and ignition may be
conducted precisely as directed for the treatment of the
corresponding potassium compounds (§ 44), except that
no provision need be made to guard against loss by the
decrepitation of the sodic sulphate.

Sodic sulphate, Na^SO^, contains 32.39" [^ of sodium or
43.66°|„ of soda, ISTa^O. Sodic chloride contains 39.32" |„
of sodium.

h. If potassium is present, the two metals being con-
verted into chlorides, ascertain the amount of the same
by evaporation to dryness and weighing the residue after
gentle ignition, as directed for the treatment of potassic
chloride (§ 44, a), and then determine the amount of po-
tassic chloride in this mixture, with the aid of platinic
chloride, as directed under potassium (§ 44, c). The dif-
ference between the sum of the two chlorides and the
amount of potassic chloride will give the sodic chloride.

In this separation, enough platinic chloride must be

§ 46. SODIUM. 53

added to convert Tjoth the potassium and the sodium into
the platinic compounds, and the evaporation with platinic
chloride should not be carried to complete dryness, so as
to avoid expelling the water of crystallization of the so-
dic salt. The filtrate from the potassic salt should have a
deep yellow color, and the salt, when examined with the
magnifier, should be seen to consist only of yellow octa-
hedral crystals or a yellow granular poAvder.

c. If sul23huric acid is present in the solution containing
sodium and potassium, the conversion of these metals into
chlorides may be effected by gentle ignition with j^owder-
ed ammonic chloride. Evaporate the solution of the sul-
phates to dryness, mix the residue with a little more than
its weight of jDure ammonic chloride, heat the mixture
gently as long as fumes are evolved, and weigh ; add more
ammonic chloride to the contents of the crucible, ignite,
and weigh again, and repeat this operation as long as
there is any change in weight.

d. In case the quantity of one metal in the mixture of
the chlorides is not very much larger than that of the
other, they may be estimated with accuracy by th*^, indi-
rect process. Determine the chlorine in the known
weight of the mixture by the volumetric process (§ 63, ^),
and then calculate the amount of potassium and sodium
in it by the following formulas, in which S = the weight
of tl^e mixture of the chlorides, and A — the amount of
chlorine contained therein.

Potassium = ^ i^n^'

e. If it is more convenient to weigh the metals as sul-
phates, the sulphuric acid may be determined in the usual

54 § 47. BASES AXD ACIDS WITH KEAGENTS.

manner (§ 59), and the respective amounts of sodic and
potassic sulphate estimated by the following formulas, in
which X = the amount of the sodic sulphate, Y that of
the potassic sulphate, A the weight of the mixed sul-
phates, and S that of the sulphuric acid contained therein.

S-(A X 0.45919)
■^ - 0.10419. ^ ^^ "^•

In determining potassium and sodium by either of these
indirect methods, it is absolutely essential that all other
metals be carefully removed.

AMMONIUM. NH4 18. AMMONIA. NH3.

47. All the salts of ammonium are either volatilized by
heat or decomposed Avith expulsion of the ammonia, and
their solubility is the same as that of the potassium salts,
except that the tartrate is more 'soluble.

Reactions. — Salts of ammonium behave like salts of
potassium, with platinic chloride, except that when am-
monic platinic chloride is ignited, nothing but metallic
platinum is left behind.

When salts of ammonium are gently heated with baric
or sodic hydrate, ammonia is expelled and gives a blue
color to a piece of moistened red litmus-paper held in the
tube above the liquid, or a brown color to a piece of tur-
meric'i^aper. To make this reaction as delicate as jDossi-
ble, put the substance to be tested in a small beaker, with
baric or calcic hydrate in a dry foim, moisten the mixture
with water, cover the beaker with a watch-glass on the
under side of Avhicli is a slip of the moistened test-paper,
and heat the whole gently. Sooner or later, the presence
of ammonium will be manifested by a change in the color
of the paper, if any is present in the substance.

The test is a delicate one, as thus performed, and none
of the metals interfere with it, if present.

§ 47. AMMONIUM. 55

A still more sensitive test is that known as Nessler's.
When a mixture of solution of mercuric iodide in potassic
iodide, and potassic hydrate, is added to a solution con-
taining ammonium, a light or reddish-brown precipitate
is obtained, NHg J. To make this test still more delicate,
as in the case of an exceedingly dilute solution of the am-
moniacal salt, add 25 c.c. of baric hydrate to a litre of
the water to be examined, distil off ^ 1^ of the mixture,
and test the distillate with the Nessler solution.

If the solution is not too dilute, a good reaction is ob-
tained on holding a drop of the Nessler solution, sus-
pended on the end of a glass rod, in the test-tube just
above a mixture of the substance tested and baric hy-
drate ; if ammonium is present, the drop is colored red-
dish-brown.

To' make a litre of the- solution for this test, and a solu-
tion that can also be used for quantitative purposes, dis-
solve 62.5 grms. of potassic iodide in 250 c.c. of water,
and add to this a concentrated solution of mercuric chlo-
ride, until the precipitated mercuric iodide ceases to be
dissolved on agitation ; then dissolve 150 grammes of
caustic potassa in its own weight of water, and add it
gradually to the iodized mercurial solution, and finally
the necessary amount of water to make one litre ; let the
mixture stand 8-10 days, decant the clear and nearly
colorless liquid, and keep it in well stoppered bottles in a
dark place.

Qaantitatiyc estimation. — a. Ammonium may be de-
termined in the form of the ammonic platinic chloride,
(NHJ^PtCl^, when all metals except sodium (and calcium
and magnesium, Stohmann^ are absent. The course to
be followed is precisely the same as that described for the
determination of potassium in the corresponding manner
(§ 44, c). The double chloride contains 7.64" |„ of ammonia
(NHJ, or 8.07° I, of ammonium.

56 § 47. BASES AND ACIDS WITH KEAGENTS.

h. Ammonia may also be determined by expulsion
from the mixture containing it by a strong base, and col-
lecting the product in a known quantity of standard acid.
[Schlossing^s process.) The solution to be examined,
which should not be more than 35 c.c. in bulk, nor con-
tain more than 0.3 grm. of ammonia, is put in a shallow
vessel, A, about 5 cm. in diameter, which, in its turn, is
put on a plate about 10 cm. in diameter, the bottom of
which is covered with mercury. Put 10 c.c. of the nor-
mal sulphuric acid in another, and rather smaller, shallow
vessel, B, that is supported over A by a glass triangle ;
then put about 10 c.c. of milk of lime or sodic hydrate in
A with the ammoniacal solution, by means of a pipette,
and finally invert a bell-jar or a weighted beaker over
the whole, and be sure that its rim is completely immers-
ed in the mercury.

After 48 hours, the ammonia will usually be entirely
expelled from the substance, and absorbed by the acid ;
in the analysis of animal and vegetable liquids, Schulze
found that three or four days were required, but that after
the expiration of that time the ammonia was completely
liberated. To test the matter, lift the edge of the bell-
jar or beaker, or take out the stopper of the tubulure, if
the bell-jar has such an appendage, and introduce a piece
of moistened red litmus-paper ; this should retain its red
color even if left for a considerable time in the jar.

If the operation is finished, titrate the acid in the vessel
B, with the standard solution of soda ; the difference be-
tween the number of cubic centimetres of acid put into
B in the beginning, and the number of cubic centimetres
of soda solution required to neutralize what acid remains
free, multiplied into 0.017 grm. will give the amount of
ammonia (NII3) in the substance analyzed— or, multiplied
into 0.026 grm. will give the amount of ammonic oxide

(Nn.),o.

If albuminoids are present in the substance examined.

§ 47. AMMONIUM. 57

it is better to use freshly ignited magnesia, instead of milk
of lime, to set free the ammonia, so as to avoid the forma-
tion of the compound out of a portion of the albuminous
matters ( Yogel).

c. When the substance does not contain, besides am-
monia, nitrogenous organic matter that would yield
more ammonia on being heated with an alkali, the de-
termination may be more expeditiously performed as fol-
lows.

Weigh the substance out in a small tube about 10 mm.
in diameter and 5 cm. long, put it in a small flask, A,
containing a moderately concentrated solution of sodic
hydrate which has been previously boiled for a consider-
able time to expel all traces of ammonia, and allowed to
cool again. Freshly ignited magnesia is sometimes used
in the place of the alkali. Put the flask in an inclined
position on the wire gauze over the lamp, and connect it
quickly with the tube of a small cooling apparatus ; con-
nect the other end of this tube by a good cork with a
tubulated receiver, J5, through the tubulure of which
passes another small tube that is bent twice and carried
to the bottom of a small flask, C. Put into the receiver,
j5, the larger portion of 50 c.c. of standard sulphuric acid
and the remainder in the flask C, and color the acid in
both vessels with a little cochineal; neither tube that
passes into JB should dip into the liquid contained in it.
Be sure, now, that the apparatus is tight throughout, boil
the contents of the flask A gently, and continue the
boiling for a little while after the drops of condensed
liquid as they fall into the receiver have ceased to change
the color of the acid as they come in contact with it.
Then remove the lamp, and allow the contents of the
flask (7 to flow back into B ; rinse C several times with
cold water, and allow these rinsins-s to flow into B also ;
finally disconnect the receiver B from the rest of the
apparatus, transfer its contents to a beaker without any
3*

58 § 47. BASES AND ACIDS WITH REAGENTS.

loss, titrate the acid remaining free with the standard so-
dic solution, and estimate the amomit of ammonia in the
substance analyzed, as directed in h. {Fresenius.)

d. If the standard acid in either of these processes,
h or c, should contain but a very small amount of am-
monia, instead of titrating with soda, the determination
may be completed more satisfactorily with the aid of the
Nessler solution, by preparing a solution containing an
accurately known quantity of ammonia, of such a strength,
that about equal volumes of it and of the solution con-
taining the unknown amount of ammonia, will give the
same shade of color with equal small quantities of this
reagent.

The color observations in this process are best made in
narrow glass cylinders of such a diameter that 100 c.c. of
the water to be tested form a stratum about 18 cm. deep,
and by placing these cylinders upon a sheet of white
paper near a window and looking at the surface of the
liquid obliquely.

The amount of ammonia present in the solution to be
examined should not be great enough to give a precipi-
tate with the reagent, but only a coloration ; the best re-
sults are obtained when there is not more than one milli-
gramme of NHg in 100 c.c. of the solution, but even if the
solution is ten times stronger than this, the results are
more accurate than those obtained by titration ; it is im-
portant that the temperature of the solution tested should
be nearly the same as that of the other solution contain-
ing a known quantity of ammonia, which is made the
standard of comparison, and that neither free potassa or
soda, nor calcic or magnesic carbonate should be present.

To estimate the ammonia in a solution by this method,
first make a standard solution of ammonic chloride con-
taining 0.3147 grm. in one litre, which is equal to 0.1
grm. of ammonia (NHg) in the litre ; add 1 c.c. of the

§ 48. BARIUM. § 49. CALCIUM. 59

standard iodized mercurial solution to 100 or 150 c.c. of
the distillate, obtained in h or c, or to any clear and color-
less solution containing ammonia ; put in another test-
tube, containing about 100 c.c. of water, as much of the
standard solution of ammonic chloride as is thought nec-
essary to give the same shade of color with the test-
liquid, make the volume of this mixture the same as
of the other, by addition of water, add 1 c.c. of the
iodized mercurial solution, let stand ten minutes, and then
compare shades of color ; if not alike, make another more
or less diluted portion of the standard ammonic solution,
according as the shade of color of the first was too dark
or too light, and repeat the test.. {W. A. Miller.)

BARIUM. Ba. 137.

48. Compounds o. barium with sulphuric, oxalic, car-
bonic, phosphoric, tartaric, and silicic acids, and with flu-
orine, are insoluble or sparingly soluble in water. The
sulphate and silicate are insoluble in acids.

Reactions* — Sulphuric acid and all soluble sulphates
produce, even in very dilute solutions of barium salts, a
finely pulverulent precipitate of baric sulphate, BaSO^,
insoluble in acids, except when hot and concentrated, and
even then but very sparingly soluble. This sulphate is
slightly decomposed when boiled with a solution of sodic
carbonate, but is not changed at all if a soluble sulphate
is mixed with the carbonate.

CALCIUM. Ca. 40.

49. Compounds of calcium with oxalic, carbonic, phos-
phoric, tartaric, and silicic acids, and with fluorine, are
insoluble or sparingly soluble in water. The tartrate dis-
solves in 352 parts of boiling water. The silicate and
fluoride are insoluble in acids. Both water and acids dis-
solve the sulphate in small quantity.

60 § 49. BASES AND ACIDS "WITH REAGENTS.

Reactions* — If dilute sulphuric acid or amnionic sul-
phate is added to a not too dilute solution of a calcic salt,
free from a large excess of strong acids, a white precipi-
tate of calcic sulphate, CaSO^, 2}Ifi, is formed immedi-
ately or after standing some time, which is soluble in an
excess of mineral acid, and slightly soluble in acetic acid
and water.

This sulphate being much less soluble in alcohox than
in water, the addition of a quantity of this reagent about
equal to the volume of the solution, will often cause the for-
mation of a precipitate, at least after standing some time,'
that would otherwise not appear.

This precipitate is readily decomposed when boiled
with a solution of sodic carbonate, calcic carbonate and
sodic sulphate being formed.

Ammonic oxalate gives, even in very dilute solutions
of calcic salts, if they contain no free mineral acid, a
white crystalline precipitate of calcic oxalate, CaC.^O^,
soluble in hydrochloric or nitric acid, and insoluble iu
acetic acid or a solution of ammonic chloride. If the so-
lution of the calcic salt is very dilute, a precipitate may
not appear until after the mixture has stood some time.

Quantitative Estimation. — Calcium is usually deter-
mined as carbonate, CaCOg, by precipitation with am-
nionic oxalate and conversion of the oxalate into carbon-
ate by ignition.

a. 1 . — If the salt is soluble in water or the acid is one
that, like carbonic acid, may be expelled by hydrochloric
acid, or can be removed by evaporation to dryness, like
silicic acid, or the solution gives no precipitate with am-
monia, add ammonic oxalate to the hot solution free from
any great excess of acid, and then ammonic hydrate imtil
the liquid, after being ivell stirred, gives off an ammoni-
acal odor, let the mixture stand in a waiTQ place 12 hours,
decant the clear liquid into a filter, wash the precifJitate

§ 49. CALCIUM. 61

several times by decantation, and finally rinse it into the
filter with hot water. Ignite the precipitate and filter
separately (§ 40, b)^ keeping the filter-ash on the crucible
cover. Keep the crucible at a fai?it red heat 5 or 10
minutes at the close of the ignition ; at no time should it
be heated to a higher temperature than this ; during this
short ignition lift the cover of the crucible a few times.

After -weighing, moisten the contents of the crucible
with a little water and apply a piece of turmeric-paper
to the moist mass ; if the paper is turned brown, rinse it
off with a very small quantity of water, put a small
lump of ammonic carbonate into the crucible, heat the
crucible over the water-bath until its contents are dry
again, ignite gently, and weigh again ; repeat this opera-
tion with fresh portions of ammonic carbonate, and igni-
tion, as long as there is any change in weight. The
change of color in the turmeric-paper showed that the
first ignition was carried too far, so as to expel some of
the carbonic acid, and leave calcic oxide. {M'esenius.)

The residue of calcic carbonate contains 40 "j^ of calci-
um or 56 ° Iq of calcic oxide or lime.

2. If a blast-lamp is at hand, or a gas blow^pipe, it is
best to ignite the precipitate of calcic oxalate 10 minutes
to an incipient white heat, after the usual ignition to a red
heat over the common lamp ; in this way all the calcic
carbonate will be converted into calcic oxide, which may
be weighed as such ; no testing of the ignited residue is
necessary, and moreover the filter may be burned with
the precipitate.

3. Instead of igniting the precipitate of ammonic oxa-
late, after it has been well washed in the usual manner,
dissolve it in dilute hydrochloric acid while yet moist,
add water in such a quantity that the ratio between the
oxalic acid and the water will be about 1 : 400 or 500,
a^ to this 6-8 c.c^ of concentrated sulphuric acid, and
then estimate the oxalic acid in this solution with the aid

62 50. BASES AXD ACIDS WITH IlEAGENTS.

of the standard permanganate solution, as directed in
§ 69, a. This method yields results that are hardly less
accurate, if any at all, than the other two already de-
scribed. For each equivalent of oxalic acid found, ex-
pressed in milligrammes^ reckon one equivalent of lime,
similarly expressed, or 0.028 grm.

If the amount of calcic oxalate in the filter is very
small, it may be converted into sulphate by ignition with
pure ammonic sulphate, and the lime weighed as sulphate,
containing 41.18 "1^ of lime.

h. If the acid in combination with the lime is one that,
like phosphoric acid, cannot be readily removed, add am-
monia until a permanent precipitate just begins to appear,
dissolve this by adding a few drops of hydrochloric acid,
add ammonic oxalate in excess, then sodic acetate, and
proceed as in a with the precipitated calcic oxalate.

MAGNESIUM. Mg. 24.

50t Compounds of magnesium with i)hosphoric, car-
bonic, oxalic, and silicic acids, and with fluorine, are in-
soluble or sparingly soluble in water. The silicate and
fluoride are insoluble in acids.

Reactions* — The carbonate is not precipitated from so-
lutions of magnesic salts containing much ammonic chlo-
ride, on addition of an alkaline carbonate.

Hydric disodic phosphate produces a white precipitate
of ammonio-magnesic phosphate, MgNH^PO^, in solutions
of magnesic salts containing ammonic salts. The precipi-
tate, at first flocculent, if at all abundant, becomes more
granular and crystalline after standing some time, or after
violent agitation of the liquid containing it. If the solu-
tion of the magnesic salt is very dilute, the precipitate
may not appear for some hours, and then it is crystalline
and adheres to the sides of the tube ; if, before the solu-
tion was set aside, it was stirred with a glass rod, and' the

50. MAGNESIUM. 63

walls of the tube rubbed here and there with the rod, the
precipitate is deposited along these lines, producing the
appearance of white streaks on the glass.

Even in concentrated solutions containing magnesium
and ammonic chloride and sodic phosphate, the whole of
the ammonio-magnesic phosphate is not deposited until
after long standing ; hence, if the first precipitate pro-
duced on adding the reagent is filtered out, and the clear
filtrate stirred and set aside, a fresh precipitation will take
place, and partly on the walls of the tube in the manner
described above.

Quantitative estimation. — Magnesium is usually deter-
mined as pyrophosj^hate, Mg^P^O^.

a. To the solution of the magnesic salt add a consider-
able quantity of ammonic chloride, and then ammonia in
slight excess ; if this ammonia causes the formation of a
precipitate, add enough more ammonic chloride to dis-
solve it ; then add hydric disodic phosphate, as long as a
precipitate is formed, stir the mixture well, with care not
to touch the sides of the beaker with the rod, cover the
beaker carefully, and let it stand with its contents 12
hours without applying heat ; decant the clear liquid
through the filter, rinse the contents of the beaker into
the filter with portions of the first filtrate, and wash the
contents of the filter with a diluted ammonia water
containing one part of ammonia water of 0.96 Sp. Gr.
and three of water, until the last five drops of the wash-
ings give no opalescence with very dilute nitric acid con-
taining argentic nitrate.

Ignite the precipitate and filter separately. Rose rec-
ommends to ignite the precipitate for a short time in a
porcelain crucible over the blast-lamp ; in this way it is
obtained quite white.

Add 0.002 grm. to the residue of magnesic phosphate
for every 110 c.c. of the filtrate from the precipitate (but

64 50. BASES AND ACIDS WITH REAGENTS.

not the washings), to compensate for the solubility of the
salt in the ammoniacal solution in which it was precipi-
tated. [Fresenius.)

The residue contains 36.04" 1^ of magnesic oxide or
magnesia, MgO.

If the solution containing the magnesium is strongly-
acid. Rose recommends that the sodic phosphate be added
first, and then a sufficient quantity of ammonia to super-
saturate the acid ; thus he prevents the formation of any
hydrated magnesic oxide that is liable to be precipitated
with the phosphate and make it impure.

h. Separation of Calcium and Magnesium. — This is
effected with ammonic oxalate in the presence of am-
monic chloride, and ammonia in slight excess. Add the
ammonic chloride and ammonia as directed above in . ',
and then ammonic oxalate ; this last reagent must be
added in slight excess, after it has ceased to give any
further precipitate of calcic oxalate, in order to convert
all the magnesium into oxalate. Let the •mixture stand
12 hours in a moderately warm place, decant the clear
liquid into the filter, wash the precipitate in the beaker
once with water, decant the washings, dissolve the pre-
cipitate in a little dilute hydrochloric acid, add ammonia
in slight excess, and ammonic oxalate ; let the mixture
stand until the precipitate has completely subsided, then
filter through the same filter as before, and wash. The
first filtrate has the larger portion of the magnesium in
it ; the second, the rest.

Acidify the second filtrate, and concentrate that and
the washings by evaporation, add the residue to the first
filtrate, and precipitate magnesium in this solution as
phosphate. Treat the precipitate of calcic oxalate on the
filter as directed in § 49.

If, in the filtrate from the calcic oxalate, there is a
great excess of ammonic salts, it will be safer to evapo-
rate the solution to dryness and expel them by ignition,

§ 51. ALUMINIUM. 65

dissolve the residue in water acidified with hydrochloric
acid, filter if necessary, and then to precipitate the mag-
nesium in the usual manner with hydric disodic phosphate.

c. If but little calcium is mixed with considerable mag-
nesium in the substance to be analyzed, evaporate the
solution to dryness, and ignite the residue gently to ex-
pel ammoniacal salts completely, dissolve this residue in a
very little water mixed with a few drops of hydrochloric
acid, add strong alcohol and a slight excess of pure con-
centrated sulphuric acid, and digest the mixture in the
cold several hours. Collect the precipitated calcic sul-
phate on the filter, wash it first with almost absolute al-
cohol and finally with alcohol of about 40 " |^, dry, ignite
and weigh.

Expel the alcohol from the filtrate and washings by
heat, and determine magnesium in the usual manner with
sodio phosphate.

ALUMINIUM. Al. 27.5.

51 • Compounds of aluminium with phosphoric and
silicic acids, and fluorine, are insohible in water. The
silicate is insoluble in acids.

Reactions. — Solutions containing aluminium give a pre-
cipitate, Al203,3H20, or AlJIgO^, with ammonic or sodic
hydrate ; the precipitate is dissolved in an excess of the
latter reagent, but not in the former.

When a compound of aluminium is fused on platinum
foil with four or five times its bulk of sodic and potassic
carbonate, the fused mass dissolved in a very little water,
and the solution filtered if necessary, nitric acid added to
the filtrate carefully until effervescence ceases, and then a
fcAV drops of ammonia until the solution emits a faint
odor of the reagent, a white flocculent precipitate appears,
at once, or after standing some time ; it will appear soon-
er, or be more readily perceiyed, on heating the liquid
gently for a time.

66 52. BASES AND ACIDS WITH IIEAGE2JTS.

QuantitatiYC estimation. — Aluminium is always weigh-
ed as sesquioxide, Al^Og.

To the not too dilute hot solution add a fourth or a
third of its volume of ammonic chloride, if not already-
present, and then ammonic hydrate until a faint odor of
ammonia is perceptible after vigorous stirring ; heat the
mixture almost to boiling nntil no more ammonia is given
off, let it stand a few hours in a moderately warm place,
decant the clear liquid through the filter, wash the pre-
cipitate two or three times Avith hot water, by decanta-
tion, transfer the whole to the filter, and wash it until the
washings leave no fixed residue on platinum foil ; if the
solution contained sulphuric acid in notable quantity, it
will be best to dissolve this first precipitate in dilute hy-
drochloric acid, and re-precipitate the aluminic hydrate
with ammonia, as above. Dry the precipitate very thor-
oughly, and ignite it gently at first, and carry the heat to
a full red, finally.

The residue is pure alumina.

IRON. Fe. 56.

52. Compounds of iron with carbonic, phosphoric,
oxalic, and silicic acids, and sulphur, are insoluble in water ;
the silicate is insoluble in acids.

Ferric salts give a yellowish-red color to solutions con-
taining them in notable quantity.

Reactions. — Solutions of ferrous and ferric salts give
precipitates, FeO, H,0, or FeH^, and 2Fe,03, 3H,0 or
Fe^HgOg, with ammonic or sodic hydrate ; the ferrous salts,
however, give no precipitate with ammonia in the presence
of ammonic salts. These precipitates are insoluble in ex-
cess of the precipitant. The precipitate produced in so-
lutions of pure ferrous salts is white j in solutions of
ferric salts, reddish-brown.

Solutions of ferrous salts give a blue precipitate with

§ 52. IRON. 67

potassic ferricyanide ; ferric salts give no precipitate with
this reagent.

Ferric salts give a deep red color with potassic sulpho-
cyanate ; this reaction is exceedingly delicate. Nitric
acid causes the color to disappear after a while, and am-
nionic hydrate destroys it immediately. Ferrous salts
give no color with this reagent.

Ferrous salts are converted into ferric compounds when
heated with nitric acid.

Quantitative estimation. — Iron may be determined by
a gravimetric or a volumetric process. In the former
case it is weighed as sesquioxide, Fe^Og.

a. Add ammonic hydrate in excess to the hot solution,
in which the iron has been completely oxidized by heating
with nitric acid, if any ferrous oxide was present, heat
the' mixture almost to boiling, and then let it stand imtil
tlie larger part of the liquid can be decanted into the fil-
ter ; wash the precipitate several times by decantation,
and afterwards on the filter, until a droj) of the washings
leaves no residue on evaporation on platinum foil, and
ignite the precipitate and filter separately. The residue
is pure ferric oxide, and contains 70"! ^ of iron.

If the substance analyzed contained silica, this precipi-
tate is liable to be contaminated with it, and should be
digested with concentrated hydrochloric acid, after hav-
ing been gently ignited ; if silica is present, it will remain
undissolved, and may be filtered out and weighed.

h. The volumetric process, with potassic permanganate,
is particularly convenient for the determination of iron
in the presence of aluminium. The iron is converted into
a ferrous salt, and then it is ascertained how much of a
solution of permanganate of known strength is required,
to oxidize the ferrous to a ferric salt.

To make the solution of permanganate, dissolve about
8 grms. of the crystallized potassic permanganate of the

68 § 52. BASES AND ACIDS WITH REAGENTS.

druggists in one litre of water ; as this solution is changed
by exposure to the air, its strength must be determined
from time to time, and the oftener, the more imperfectly
it is protected from such exposure.

To determine its strength, weigh out accurately about
1.4 grms. of ammonio-ferrous sulphate, dissolve the salt
in about 200 c.c. of distilled water, to which about 20 c.c.
of dilute sulphuric acid have been added. To protect the
salt more completely from oxidation while the solution is
taking place, heat it with a part of the water in a small
flask closed by a cork through which two short glass
tubes pass ; fasten the flask in an inclined position in a
retort-holder, and heat its contents while a slow current
of carbonic acid is conducted through the upper part of
it. When the solution is completed, let the liquid cool in
the current of carbonic acid, transfer it quickly to a beak-
er or a larger flask, rmse the flask out with the rest of
the water, set the vessel over white paper, and immedi-
ately begin to add the solution of permanganate from a
burette, with constant stirring of the liquid. At first,
the red drops disappear the instant that they come in
contact with the solution, and the latter gradually takes
a yellowish tint ; add the permanganate more and more
carefully as the drops begin to disappear less readily, and
stop when the last drop gives an unmistakable reddish
color to the whole liquid.

Ammonio-ferrous sulj)hate contains just one-seventh of
its weiglit of iron, and hence the amount of permanganic
solution used in this trial will convert a weight of
iron from ferrous to ferric oxide, equal to one-seventh of
the weight of tlie salt taken.

The concentration of the solution of permanganate
should be such, that from 20 to 30 c.c. is required for 1.4
grms. of ammonio-ferrous sulphate, or 0.2 grm. of metal-
lic iron.

Now, to determine iron by this process the ferric salt

§ 52. iRoif. 69

must be in the form of a sulphate or a chloride, and the
solution should contain about 0.5 grm. of iron and an
excess of free sulphuric or hydrochloric acid and as little
nitric acid as possible ; heat the solution in a small, long-
necked flask placed in an inclined position, drop in a few-
pieces of pure zinc, and conduct carbonic acid through
the flask in the same manner as described above, for dis-
solving the ferrous salt ; the ferric compound is reduced
to a ferrous salt by the zinc, with the evolution of hydro-
gen. When the solution is decolorized, and all the zinc
is dissolved, cool the liquid as quickly as possible by im-
mersing the flask in cold w^ater, while carbonic acid is
still passing through, transfer the solution to a beaker,
rinse the flask into the beaker with a considerable quanti-
ty of w^ater, and dilute the solution until it contains about
200 c.c. for every 0.2 grm. of iron supposed to be present ;
the solution must be more largely diluted if the salt was
a chloride, or w^as dissolved in hydrochloric acid, instead
of sulphuric.

To this solution add the solution of permanganate in
the same manner as directed above, for the treatment of
the ferrous salt.

The amount of iron m the quantity of solution taken
will be given by the proportion

C : F = C^ : X
7
in which C = the number of cubic centimetres of per-
manganic solution used in the trial with the known quan-
tity of ferrous salt, F = the weight of the ferrous salt
taken, C = the number of cubic centimetres of perman-
ganic solution used in the trial with the substance exam-
ined, and X = the amount of iron therein.

The solution of potassic permanganate is most con-
veniently kept in a bottle provided with an ordinary
w^ashing-bottle arrangement for filling the burette from
it • then the bottle need not be opened until empty, no

70 52. BASES AND ACIDS WITH EEAGENTS.

dust can get into it, particularly if the open end of the
shorter tube is closed with a plug of cotton, and its
strength will not change perceptibly in two or three
months.

c. The following volumetric method of estimating fer-
ric oxide has given satisfactory results ( Oudemans^ Fre-
seniiis's Zeitschrift, 6, 129), and is very easily executed.

Prepare a standard solution of sodic hyposulphite, by
dissolving 24.8 grms. of the pure crystallized salt in one
litre of water; this gives a ^1,^ normal solution, since 248 <
is the equivalent of the crystallized salt. Determine the
strength of a solution of ferric chloride containing no
traces of free chlorine, as carefully as possible, by precipi-
tation with ammonia (a).

To a quantity of this solution, accurately measured,
containing about 0.2 grm. of iron, add a littl6 hydrochlo-
ric acid, one or two drops of a concentrated solution of
cupric sulphate, and the same quantity of potassic sulpho-
cyanate ; heat this blood-red liquid to about 40° C, and
allow the standard solution of hyposulphite to flow from
a burette into it Avith constant stirring, until the red color
disappears, leaving a clear, colorless liquid ; towards the
end of the operation, when the color of the solution has
become quite pale, wait a few seconds between each ad-
dition of a few drops of the hyposulphite. Divide the
quantity of ferric oxide corresponding to the amount of
ferric chloride taken, by the number of cubic centimetres
of the solution of hyposulphite required in this trial, and
the quotient will give the amount of ferric oxide which
the sodic hyposulphite in one cubic centimetre of the
standard solution is able to reduce to protoxide.

Having in this way determined the value of the solu-
tion of hyposulphite with reference to ferric oxide, this
oxide may be determined in any solution containing it or
the corresponding chloride, in the manner described

§ 53. MANGANESE. 71

above ; the solution should contain no free chlorine or ni-
tric acid.

The standard solution of hyposulphite should be care-
fully protected from the light, and the determination of
its strength should be repeated from time to time by com-
parison with a portion of the solution of ferric chloride
of known strength, as above.

MANGANESE. Mn. 55.

53 • Compounds of manganese with phosphoric, car-
bonic, oxalic, and silicic acids, and sulphur, fluorine, and
cyanogen, are insoluble or sparingly soluble in water.
The silicate is insoluble in acids.

Reactions. — A solution containing manganese gives a
precipitate, MnO,H20, or MnH^O^, with sodic or ammonic
hydrate ; the presence of ammonic chloride prevents the
formation of the precipitate by ammonic hydrate ; in this
way manganese may be partially separated from iron for
qualitative purposes.

When a compound of manganese is fused with potassic
and sodic carbonate and sodic nitrate, the fused mass
takes a bluish-green color, which can be masked only by
the presence of a very considerable quantity of iron. In
case this large proportion of iron is present, it may be
precipitated by ammonia after adding considerable am-
monic chloride, filtering it out quickly, and evaporating
the filtrate ; then test a few drops of the concentrated
liquid by fusion, as above.

Quantitative estimation. — The manganese is usually
precipitated as carbonate ; when ignited, this carbonate is
converted into manganous manganic oxide, MugO^, which
is weighed. Heat the solution, free from any great excess
of mineral acid, nearly to boiling in a capacious flask, add
sodic carbonate very slowly until it is in excess, boil a few
minutes, and wash the precipitate by decantation and on

72 § 54. BASES AND ACIDS WITH REAGENTS.

the filter; ignite the filter and its contents separately.
The ignition should be carried to a full red heat. The
residue contains 72.05" j^ of manganese.

ZINC. Zn. 65.

54. Compounds of zinc with phosphoric, carbonic, ox-
alic, and silicic acids, and sulphur and cyanogen, are in-
soluble or sparingly soluble in water. The silicate is
insoluble in acids.

Reactions. — Solutions of zincic salts give a white pre-^
cipitate, ZnO, H^O or ZnH^O^, with sodic or ammonic
hydrate, soluble in excess of the precipitant, and re-pre-
cipitated from this solution on dilution with considerable
water and boiling.

Solutions of zincic salts give a white flocculent precipi-
tate, Zn^Fe^Cyg, with potassic ferrocyanide, that is diffi-
cultly soluble in acids.

LEAD. Pb. 207.

55. Compounds of lead with sulphuric, phosphoric, car-
bonic, oxalic, and tartaric acids, and sulphur and fluorine,
are insoluble, or sparingly soluble in water. The sulphate
and sulphide are insoluble in dilute acids.

Reactions. — Solutions of salts of lead give a white pre-
cipitate, 2PbO, H^O or Pb^H^Og, with sodic or ammonic
hydrate, insoluble in excess of the precij^itant.

If free from a very large excess of strong acid, they
give a white precipitate, PbSO^, with dilute sulphuric
acid, which appears at once, or after some time if the so-
lution is very dilute ; this precipitate is insoluble in dilute
acids, and is more insoluble in dilute sulphuric acid than
in pure water ; it i^ soluble in a solution of ammonic tar-
trate containing an excess of ammonia ; if this solution
is acidified with acetic acid and potassic dichromate add-

§ 56. COPPER. § 57. ARSENIC. 73

ed, a yellow precipitate of plumbic chromate, PbCrO^, is
formed.

Lead is precipitated from its solutions by metallic zinc
in the presence of free acid.

COPPER. Cu. 63.5.

56. Compounds of copper with phosphoric, oxalic, car-
bonic, tartaric, and silicic acids, and sulphur and cyanogen,
are insoluble, or sparingly soluble in water. The sulphide
and silicate are insoluble in dilute acids.

Cupric salts give a blue or a greenish-blue color to so-
lutions containing them.

Reactions* — Solutions containing copper give a green-
ish precipitate, CuO, H^O or CuH^O^, with sodic or am-
monic hydrate. This precipitate is dissolved by an excess
of ammonic hydrate, giving a deep blue solution ; the
reaction is very delicate.

Solutions of copper give a red precipitate with potassic
ferrocyanide, Cu^Fe^Cyg.

Copper is j^recipitated from its solutions by zinc in the
presence of free sulphuric or hydrochloric acid; free
nitric acid hinders the reduction, but does not prevent it.

ARSENIC. As. 75.

57. When a solution containing arsenic is treated with
dilute sulphuric acid and metallic zinc, in a small flask
closed with a cork through which passes a glass tube
drawn out to a small jet at the end, and the escaping gas
is lighted, after it has been evolved long enough to expel
the oxygen from the flashy a bluish flame is produced,
which deposits black, shiny spots on a cold porcelain sur-
face. The arsenic was evolved as arseniuretted hydrogen,
AsIIg. This reaction is very delicate, and is known as
Marsh's test.

4

74 § 58. BASES AND ACIDS WITH REAGENTS.

ACIDS.
SILICIC ACID. HaSiOg.

58. All silicates are insoluble in water and dilute acids,
except those of potassium and sodium.

Silicates may be decomposed, and the metals contained
in them brought into a soluble form, by means of concen-
trated hydrochloric or sulphuric acid, by hydrofluoric acid
or ammonic fluoride, or by fusion with an alkaline carbon-
ate, and subsequent treatment with dilute hydrochloric^
acid.

Reactions. — If a solution of a soluble silicate is evapo-
rated to dryness, after addition of hydrochloric acid, the
residue gently ignited and treated with dilute acid, the
silica remains undissolved in the form of a white, gritty
powder.

When a silicate in powder is fused in a bead of sodic
carbonate, on platinum wire, the carbonic acid is expelled
by the silicic, and its evolution causes the bead to froth.

If a very small fragment of an insoluble silicate is
fused in a bead of phosphorus-salt, on platinum wire,
the bases are dissolved out, and the silica remains floating
about in the bead, retaining the form of the original
fragment.

Quantitative estimation. — Silicic acid is always weighed
as such.

a. 1. — If the acid is to be determined in a solution or
a soluble silicate, add an excess of hydrochloric acid to
the solution, or the very finely powdered solid, antt
evaporate the mixture to dryness on the water-bath with
frequent stirring to break up tlie lumps.

If, as is sometimes the case, the solution analyzed con-
tains organic matter, or ferrous oxide, add a few drops of
nitric acid towards the close of the evaporation. If a solid
is being treated, the digestion should be continued, with

§ 58. SILICIC ACID 75

the addition of fresh quantities of acid if necessary, until no
gritty particles can be felt under the end of the stirring
rod. Heat the residue to a temperature somewhat above
100°, in an air-bath, made by suspending the dish on wires
inside of an iron dish, so that there shall be a space of
about 12 mm. between the two at all points; when the
whole is completely dry and no more acid fumes escape,
moisten the residue with concentrated hydrochloric acid,
let it stand half an hour, add water, and digest the mix-
ture awhile, wash the insoluble residue two or three times
by decantation, wash well on the filter, dry, and ignite.
The residue is generally pure silicic acid.

All the bases with which the silica was combined can
be determined in the filtrate from it.

2. Sometimes this residue is mixed wdth sand which it
may be desired to estimate.

In this case collect the mixture on a dried and weighed
filter, dry it at 100° C, and weigh it ; then separate it
from the filter as completely as possible without tearing
the latter, and boil it Avith several portions of a concen-
trated solution of sodic carbonate, or with sodic carbonate
to which about ^ |^ of sodic hydrate has been added, or
with sodic hydrate alone; dilute each portion of the
liquid if it contained much free alkali, let it cool, and
throw it on the same filter from which the mixture of
silica and sand was taken ; finally, transfer the insoluble
sand to the same filter, wash it well, dry, and ignite. If
the extraction of the silica was performed in a silver dish,
the amount taken into solution by the alkaline liquids
may be estimated also ; for this purpose, evaporate all the
filtrates and washings to dryness, after having added an
excess of hydrochloric acid, and determine the silica as
in a.

3. Sometimes, in agricultural analyses, this residue con-
tains, besides silica and sand, free carbon, or coal. In
this case, dry the whole at 100° and weigh it, separate it

76 § 58. BASES AND ACIDS ^VITII IlEAGE^TS.

from the filter as above, treat it with the alkaline solu-
tions also in the same manner, collect the residue that is
insoluble in the alkali on a dried and weighed filter, dry
and weigh it, and finally ignite and weigh again. The
first of the three weighings gives the total amount of
silica, sand, and coal, the second the sand and coal, and
the third the sand alone.

h. If the silicate is insoluble in water or acids, pulverize
it until an impalpable pow^der is obtained, mix a weighed
quantity of it, in a platinum crucible, with four parts of
finely powdered j^otassic sodic carbonate, as intimately as
possible by stirring with a glass rod ; wipe the glass rod
Avith a little more of the carbonate on a slip of glazed
paper, and transfer this from the paper to the crucible ;
the latter should not, with all its contents, be more than
two-thirds filled. Cover it well and heat at first moder-
ately over a blast-lamp, or, after imbedding it in calcined
magnesia in a Hessian crucible, in a furnace ; carry the
heat gradually to an intense red ; after about 20 minutes
the mass will have ceased to boil and bubble, and the
operation is finished. Put the crucible, when cold, into a
beaker with' considerable water, and add hydrochloric
acid gradually, as directed for the solution of carbonates,
§ 36 ; when the mass is entirely loosened from the cruci-
ble, take the latter out, rinse it carefully into the beaker,
transfer the contents of the beaker to a platinum or a
porcelain dish, evaporate to dryness, and eliminate silicic
acid, as in a.

c. Of course potassium and sodium cannot be deter-
mined in the filtrate from the silica in 6, since both metals
have been added to the substance in a large and undeter-
mined quantity.

For the determination of these elements the silicate
must be decomposed with the aid of hydrofluoric acid or
a fluoride.

§ 53. SILICIC ACID. ^

1. Decomposition with hydrofluoric acid.— Proviae a

leaden cup about 16 cm. in diameter and 16 cm. deep
with a close-fitting cover, with projections on the sides
about 8 cm. from the bottom, supporting a perforated
shelf, and with a shallow tray in the bottom about 12 cm.
in diameter and 3 cm. deep, all made of lead ; spread a
layer of finely powdered fluor spar about 12 mm. deep,
over the bottom of the tray in the cup, and mix it with
enough concentrated sulphuric acid to make a thin paste ;
put the shelf in its place and on the shelf a shallow plat-
inum dish, such as a crucible cover, containing 1-2 grms.
of the very finely j^ulverized and carefully weighed sub-
stance, spread over the surface of the dish in as thin a
layer as possible and moistened with sulphuric acid ;
put the cover on the cup, and set it in a warm place
wliere the temperature is about 60° or 70° C, and lift
the cover a few times in the course of the digestion ;
the evolution of the hydrofluoric acid should be main-
tained all the time. After 48 hours take the substance
out, expel most of the sulphuric acid by heat, boil the
residue with dilute hydrochloric acid, and, if anything
remains undissolved, treat this residue with hydrofluoric
acid in the same manner as above described. The
alkaline metals can be determined in this solution by
hydrochloric acid.

2. Decomposition by ammonic fluoride. — This method
is considered by many to be easier of execution and more
certain in its results than the other. Mix the very finely
pulverized silicate with 4-5 times its weight of ammonic
fluoride in a platinum dish, moisten the mixture thorough-
ly with concentrated sulphuric acid, and heat the whole
on the water-bath in a place where the fumes of hydro-
fluoric acid will bo carried oif speedily; after a time,
when the evolution of acid fumes has ceased, moisten the
residue again with sulphuric acid, and heat it, directly
over the lamp at last, until it is completely dry and all

78 § 59. BASES AND ACIDS WITH EEAGENTS.

the sulphuric acid is expelled ; digest the residue with
hydrochloric acid; it should be dissolved completely,
although, if calcium is 2)resent, considerable time may bo
required. If the solution is not complete, the insoluble
j^art should be treated again with amnionic fluoride.

SULPHURIC ACID. 112804.

59. The sulphates of lead, barium, and calcium, are in-
soluble, or difficultly soluble, in water and dilute acids ;
the last of the three is much the most soluble.

Reactions* — Sulphuric acid and solutions of sulphates
give a finely pulverulent 2)recipitate, BaSO^, with baric,
chloride, insoluble in water or dilute acids ; the reaction
is very delicate.

Quantitative estimation. — This acid is always de-
termined as baric sulphate, BaSO^. Heat the slightly
acid solution nearly to boiling, and add a hot solution
of baric chloride as long as a precipitate is formed ;
let the mixture stand until the j^recipitate settles, and
wash the latter by decantation, until the washings
give no reaction for barium with sulphuric acid ; then
pour 40 or 50 c.c. of the solution of cupric acetate
(§ 9) over the precipitate in the beaker, add some water
and so much acetic acid that, after digestion for 10
or 15 minutes at a temperature very near to boiling, no
basic cupric salt separates from the solution ; if any does
appear, dissolve it by adding mere acetic acid ; stir the
mixture constantly during the digestion. Filter, wash
the precipitate with hot water, and, if the filter is still
colored blue, moisten it with a little dilute hydrochloric
acid and wash with more water, until the washings give
no reaction for copper with potassic ferrocyanide. Ignite
the precipitate and filter separately. The residue con-
tains 34.31" |„ of sulphuric anhydride, SO3, or 13.73° |„ of
sulphur.

§ 60. CARBONIC ACID. 79

Unless the precipitated baric sulphate is washed, as
above directed, with a solution of cupric acetate, the re-
sult of the analysis may be very unreliable, particularly
if notable quantities of nitrates or alkaline salts were
present.

CAEBONIC ACID OR ANHYDRIDE. CO2. 44.

60« Carbonates of all except the alkaline metals are
insoluble, or sparingly soluble in water ; all carbonates,
without exception, are dissolved by dilute acids, with the
expulsion of carbonic anhydride, CO^.

Reaction. — When dilute nitric or hydrochloric acid is
added to a carbonate, whether a solid or in solution, the
anhydride is expelled with effervescence, and if a drop
of lime-water, suspended on the end of a glass rod, is
held in the tube just above tlie liquid, it is made turbid
by the formation of insoluble calcic carbonate.

Quantitative estimation. — Carbonic acid is usually
estimated by the loss of weight suffered by the carbonate
on treating it with a stronger acid, or by collecting and
weighing the expelled anhydride itself.

a. For the first method a convenient form of an ap-
paratus is represented in the adjoining figure.

The carbonate is weighed in the flask A and water is
added. B is nearly filled with
nitric acid ; C contains fused calcic
chloride to absorb the^ moisture
from the carbonic acid as it passes
out, and so retain it in the appara-
tus. The apparatus being put to-
gether, with water enough in the
flask A to cover the mouth of the
tube leading from B^ close the
mouth of the tube at e with the finger, and suck a
very small quantity of air out at d; on letting air in

Fiff. 3.

80 § 60. BASES AND ACIDS WITH KEAGENTS.

again at c?, the water will rise in the tube leading from
A to -S, and, if the apparatus is tight, will remain at a
stationary level above that of the water outside of the
tube. Now, weigh the whole apparatus, apply suction at
d to cause a little nitric acid to flow over into A from
time to time, and in this manner keep up a slow evolution
of carbonic acid ; when all the carbonate is decomposed,
and all the nitric acid transferred to the flask, apply a
little heat to the latter ; then, by suction at c?, draw air
through the apparatus as long as any acid taste is jDcr-
ceived in the gas, let the apparatus cool, and weigh it.
The air should be caused to pass through a calcic chloride
tube before it goes into the apparatus, in order to dry it
thoroughly.

The loss of weight sufiered by the whole apparatus
equals the carbonic anhydride, CO^.

This method, otherwise very convenient, is, according
to Prof. S. "W. Johnson, (American Journal of Science
and Arts, Second Series, 48, 111) liable to the objection,
that in freeing the apparatus completely from carbonic
acid, some vapor of water escapes the desiccating materi-
al. He therefore proposes to fill the apparatus with car-
bonic acid gas before weighing it, and then to weigh it
again as soon as the decomposition of the carbonate is
completed ; it is essential only, that the substance under
examination dissolve freely in cold acid, and that the
analysis and weighings be conducted in an apartment not
liable to changes of temperature.

His apparatus may be closely imitated by substituting
for the acid reservoir in the above figure, another one
consisting of a bulb of sufficient size blown on a tube of
which one end, that passes just through the cork in the
flask, has an internal diameter of 7 mm., is cut ofl' oblique-
ly, and bent so that, on inclining the whole apparatus
when put together, the acid can be made to flow from the
bulb into the flask ; the other end of this tube is turned

§ 60. CARCONIC ACID. 81

upwards. Short pieces of thick- walled rubber tubing that
Avill fit snugly on the outer termination of the calcic chlo-
ride tube and the acid reservoir, at d and 6, are slipped
over them, and these rubber tubes are then provided with
well-fitting stoppers of glass rod ; all thes3 joints must
be air-tight.

The carbonate is weighed as usual in the flask, A, bet-
ter in the form of small fragments than of a powder, tlie
acid reservoir is nearly filled with hydrochloric acid
(Sp. Gr. = 1.1), the, apparatus is j^ut together, and, after
the glass-rod stoppers are removed, it is. connected with a
generator of carbonic acid, and a rather rapid current of
vrashed gas is passed through for about 15 minutes, or
until the acid in the reservoir is saturated, and the air
displaced in the flask ; then stop the opening at c?, discon-
nect-the apparatus from the generator, and close the open-
ing at e, with care in this and all subsequent operations to
handle the apparatus so as not to change its temperature.

Weigh it immediately, loosen the stopper at J, and in-
cline the whole so that the acid will flow over, little by
little, and produce a slow decomposition of the carbonate.
Close d again when the decomposition is ended, let the
apparatus stand about 15 minutes, to be sure that it is
cool, pass well-dried carbonic acid gas in again for about
a minute, in the same manner as at first, and finally weigh
it after closing d and e.

h. For the second method the following form of ai>
paratus is liighly recommended by Fresenius.

In the apparatus represented by this figure e contains
soda lime or caustic potash in pieces, a is a flask of about
300 c.c. capacity, the arm / of the first U tube is filled
with fused calcic chloride, and the arm/ with pumice-stone
that has been soaked in a concentrated solution of cupric
sulphate, dried, and gently ignited so as to drive out the
water of crystallization of the salt ; g contains pieces of
glass, 6 to 10 drops of concentrated sulphuric acid in the
4*

82

60. BxVSES AXD ACIDS WITH EEAGENTS.

bottom and plugs of asbestos in the upper parts of both
arms ; A is ' 1^ filled with about 20 grms. of coarse grained
soda lime, and the remaining ^ |g at h' is filled with coarse-

ly pulverized calcic chloride ; the arm k of the last IT
tube contains calcic chloride, and the arm k' soda lime.

The carbonic acid evolved in a is deprived of its water
and hydrochloric acid in j^' ; g enables the operator to
observe the rapidity of the flow of the gas, while the acid
is absorbed and weighed in (j and AA'/ the contents of
kk' prevent carbonic acid and water from reaching the U
tube, hh' ^ from the atmosphere.

Weigh out the substance in a, add water, weigh g and
hli' together, connect the various j^arts of the apparatus
with each other, and the little funnel d with J, and put a
few drops of mercury in at d so as to close the tube at i.

Pour the usual quantity of dilute nitric or hydrochloric
acid in at f/, and, by suction at /, cause a little of the acid to
flow over into the flask ; regulate the flow of tlie gas by
slowly transferring fresh quantities of acid from h to c?,
and applying a gentle heat to the contents of the flask.

When the carbonate is completely decomposed, fill d
several times with hot water and transfer the same to a ;
then, substitute the calcic chloride tube e for the funnel d^

§ 61. piiosPHomc ACID. 83

bring the contents of the flas'c to a gentle boiling, and
continue the application of the heat until the bulb on /
becomes hot ; draw about 1800 c.c. of air through the
apparatus, by means of an aspirator connected with I,
then immediately separate a from /, and weigh ^ and hh'
again when they have become cold. The increase in
weight gives the carbonic anhydride.

The tube ^ can be used several times if it is carefully
closed when not in use. If the tube hh' is used a second
time, it will be safer to connect another with it on the
outside, filled in the same way ; if this second tube does
not gain in weight, the first one may be used a third time,
with the same j^recaution ; if it does gain notably, use it
alone in the third analysis, and re-fill A A'.

c. It often happens that carbonic acid and chlorine are
to be estimated in the same substance ; in this case, after
making the determination of the acid by either of the
above methods, using, of course, pure nitric acid to set it
free, filter the contents of the flask if not perfectly clear,
and precipitate the chlorine in the filtrate and washings
with argentic nitrate.

PHOSPHORIC ACID. H3PO4. 98.

61 • All phosphates except those of the alkaline metals
are insoluble in water, but all are soluble in acids.

Reactions. — When a solution of a phosphate is added
to one of magnesia containing an ammoniacal salt and
an excess of ammonia, a white flocculent precipitate,
MgNH^PO^, is produced, which, after standing for a
time in a warm place, becomes more granular and crys-
talline ; in very dilute solutions the precipitate does not
appear until after long standing, and is then crystalline,
and adheres to the sides of the tube in the same manner
as described under magnesium.

84 § 61. BASES AND ACIDS WITH KEAGENTS.

When a very small quantity of a solution of a phos-
phate is added to a considerable quantity of a solution of
amnionic molybdate, containing an excess of nitric acid,
a lemon-yellow, pulverulent precipitate is formed, at once
or after long standing ; a portion of the precipitate ad-
heres strongly to the sides of the tube. This precipitate
is soluble in a solution of a phosphate and in ammonia,
but is insoluble in dilute nitric acid in the presence of
excess of the molybdate. The reaction is exceedingly
delicate.

Quantitative estimation. — a. In cases where the acid
is free or combined with an alkaline metal only, the deter-
mination of it may be made as magnesic phosphate.
Mo- P O .

■^-^&2-^ 2^7*

Neutralize a quantity of the solution of the substance
containing not more than 0.2 grm. of the acid with am-
monia, if it is acid, and add magnesia mixture {§ 18, h)
as long as a precipitate is formed ; 12-15 c.c. of the re-
agent will be required for 0.2 grm. of ^fi,^ ; then add
diluted amnionic hydrate containing one part of ammonia-
water of 0.96 Sp. Gr. and "three of water, until the vol-
ume of the mixture is about 110 c.c, and proceed further
as directed for the treatment of the same precipitate un-
der magnesium (§50, a). It contains 63.96° |„ of phos-
phoric anhydride, PjOj..

If in any case the precipitate has a somewhat suspi-
cious flocculent appearance, and does not become crystal-
line after long digestion, it had better be dissolved in
dilute hydrochloric acid on the filter ; evaporate the solu-
tion to dryness on the water-bath, treat the residue with
dilute hydrochloric acid, and precipitate the phosphoric
acid again with magnesia mixture as before. Kevcrthe-
less it is best to avoid the necessity of this re-solution and
re-precipitation if possible, by careful attention to the di-
rections for removing silicic acid and other substances
from the solution at the proper time and in the proper

§ 61. PHOSPHORIC ACID. 85

place ; according to Kubel ( Versuchs Stationen, 10, 123)
there is a lo3s of magnesia when the i)recipitated plios-
phate is dissolved and re-precipitated.

b. In the presence of alkaline earths, alumina, ferric
oxide, and manganous oxide, phosphoric acid is best de-
termined indirectly, by precipitation as ammoulc phospho-
molyhdate. If silica is present, it must first be removed
by evaporation to dryness in the usual manner (§ 58, «, 1).

. To the solution, free from silicic acid, add the solution
of ammonic molybdate containing an excess of nitric
acid, whose preparation is described in § 3, /, and
which, if made as there directed, contains 5''|o of molyb-
dic acid, in sucli a quantity that the amount of molybdic
acid added shall be from 40 to 60 times as great as that
of the phosphoric acid supposed to be in the solution ;
since the molybdic acid must be so largely in excess, it is
well to take a quantity of the solution of phosphate that
contains not over 0.1 grm. of the acid, and the solution
sliould be tolerably concentrated. Digest the mixture
from 12 to 24 hours at a temperature of about 40° C. ; then
take out a small sample of the clear liquid with a pipette,
mix it in a test-tube with its volume of ammonic molyb-
date, and heat the mixture gently for an hour or more.
If more of the precipitate appears, rinse the test-tube into
the beaker again, add more ammonic molybdate, digest
12 hours longer, and repeat the test. Not until the mix-
ture remains perfectly clear in this test may the precipita-
tion be considered as finished.

Collect the precipitate on a small filter, rinse the beaker
out with portions of the filtrate, and wash the contents
of the filter with a mixture of 100 parts of the solution of
ammonic molybdate, 20 parts of nitric acid (Sp. Gr. = 1.2),
and 80 parts of water {i^es. Zeitschrift 6, 405), until, in
case lime was present, the filtrate gives no turbidity in
strong alcohol to which sulphuric acid has been added.
Dissolve the precipitate in the smallest quantity of am-

86 61. BASES AXD ACIDS WITH REAGENTS.

monia (Sp. Gr. = 0.96), wash out tlie filter wiih a mix-
ture of 3 parts of water and 1 of ammonin, and wash off
what remains adhering to the walls of the beaker, in
Avhich the phospho-molybdate Avas precipitated, with a
little of the same ammonia water, or else collect this so-
lution of the whole precipitate in that beaker ; add di-
lute hydrochloric acid to the strong ammoniacal solution,
until the yellow precipitate, that appears with each drop
of the acid added, begins to dissolve again with some dif-
ficulty, showing that the ammonia is nearly neutralized,
then add the magnesia mixture as long as a precipitate is
produced, and the proper amount of the diluted ammonia,
and proceed as in a.

LatschinoAV (Fres. Zeitschrift 7, 215) asserts that this
precipitate of ammonio-raagnesic phosphate must be fused
with potassic sodic carbonate, the fused mass extracted
Avith water, and this solution precipitated again with the
magnesia mixture in the usual manner, after addition of a
little citric acid.

c. In the absence of at least all but small quantities of
iron and aluminium, phosphoric acid may be determined
with sufiicient accuracy for industrial purposes by a volu-
metric method, that depends upon the following reactions.
First, when a solution of uranic salt is added to one of a
phosphate containing no other free acid than acetic, the
uranic oxide is immediately precipitated in combination
with phosphoric acid. Second, a solution containing the
least traces of uranic oxide gives a brown precipitate with
potassic ferrocyanide.

Preparation of the standard sohitlo7is.

1. Dissolve 12.6056 grms. of pure crystallized hydric
disodic phosphate, that does not show the least signs of
efilorescence, and lias been thoroughly dried in powder
by pressure between folds of bibulous paper, in about 300
c.c. of water, and, when the temperature of the solution
is 15° C, make the volume up to exactly 500 c.c. with dis-

61. PHOSPHORIC ACID. 87

tilled water. One cubic centimetre of such a solution con-
tains 0.005 grni. of phosphoric anhydride, P20^.

2. Dissolve 100 grms. of sodic acetate in 900 c.c. of
water, and add 100 c.c. of concentrated acetic acid.

3. Dissolve about 33 grms. of uranic acetate in about
1 litre of water, and j^roceed to titrate this solution witli
reference to the standard solution of phosphate so that 1
cubic centimetre of it shall exactly precipitate 0.005 grm.
of phosphoric anhydride, as follows.

Put 25 c.c. of the standard phosphatic solution in a
small flask, add 5 c.c. of the solution of sodic acetate,
heat to about 50° C, add 5 or 10 c.c. of the uranic solution
from a burette or graduated pipette, heat to boiling, and
let the mixture stand a few minutes ; the precipitate wi.l
settle quickly, and a drop of the clear supernatant liquid
can be taken out on the end of a small glass rod, and
tested with the solution of potassic ferrocyanide for ex-
cess of uranic oxide ; this test is best made by letting the
drop fall gently in the middle of a small shallow pool of
the solution of ferrocyanide, on a white porcelain plate,
when the slightest excess of the uranic oxide in the solu-
tion will be manifested by the formation of a brown zone
where the two liquids come in contact; the color soon
spreads throughout the entire liquid. If no color appears,
add 5 c.c. more of the uranic solution, boil again, let set-
tle, and test a drop of the supernatant liquid in another
little pool of the ferrocyanide, and so proceed until a
brown color is produced in the test drop. Suppose that
this brown color was obtained after adding 20 c.c. of the
uranic solution, but not after adding 15 ; repeat the trial
now with a fresh quantity of the standard phosphatic so-
lution, adding 16 c.c. of the uranic solution at once, be-
fore making the test, and repeating the test after each
addition of a cubic centimetre at a time. If, in this trial,
we find that a brown color is obtained with IT c.c. but
not with 16, we may make a third trial with another por-

88 62. BASES AXD ACIDS WITH *IlEAGE>sTS.

tion of the standard pliosphatic solution, and locate the
point of saturation more accurately between 16 and 17
cubic centimetres, beginning with 16.1 c.c. and so on.

If we find, finally, that 25 c.c. of the standard phos-
phatic solution requh-es 16.5 c.c. of the uranic solution for
the complete precipitation of the phosphoric acid, then,
evidently, to every 16.5 c.c. of the former, 8.5 c.c. of pure
water must be added, in order to make a standard uranic
solution, each cubic centimetre of which shall be exactly
equivalent to 0.005 grm. of phosphoric anhydride.

The respective quantities of uranic solution and wa>er
being carefully measured out and mixed, for making half
a litre or a litre of the standard solution, this solution
should be tested, in order to be sure of its value with
respect to phosphoric acid. Dilute 5 c.c. of the standarl
phosphatic solution, add 1-2 c.c. of sodic acetate, and
then add the uranic solution from a burette graduated into
^ Ijq cubic centimetres ; exactly 5 c.c, not a tenth more or
less, should be required before the reaction with the ferro-
cyanide is given.

The method of determining phosphoric acid volumet-
rically, with the aid of this standard uranic solution, is
the same as that just described for the determination of
the strength of this solution as originally prepared. The
amount of phosphoric anhydride in the quantity of the
solution taken is then given, by the product of 0.005
into the number of cubic centimetres of standard uranic
solution required to precipitate the acid.

NITRIC ACID. IINO3. 68.

62. All nitrates are soluble in water.

Reactions. — If a nitrate is heated with concentrated
sulphuric acid and copper turnings, red fumes of nitric
peroxide, NO3, become visible in the upper part of the

62. NITKIO ACID. 89

tube, particularly if it is held over white paper and looked
through lengthwise.

If a nitrate is mixed in a test-tube with strong sul-
phuric acid and the mixture is allowed to cool, and a con-
centrated solution of ammonio-ferrous sulphate is then
poured slowly down the sides of the tube so as to float
on the surface of the liquid in it, a colored ring is formed,
the tint of which may range from a rose color to a dark
brown, according as little or much nitric acid is present.

If a solution of a nitrate is poured into a test-tube con-
taining 2-3 grms. of a mixture of clean iron filings and
granulated zinc, or of sodium amalgam, and 5-6 c.c. of a
strong solution of potash or soda are added, and the mix-
ture is heated to boiling, ammonia is set free ; its presence
in the tube may be detected by moistened turmeric-paper,
or by holding in the tube 'a drop of Nessler's solution,
suspended on the end of a glass rod ; this solution will be
colored reddish-brown.

A delicate test for nitric acid in rain-water consists in
acidifying 100 c.c. of the water with 2 or 3 drops of con-
centrated sulplmric acid, adding 2 or 3 pieces of pure
zinc, and, immediately, a freshly prepared mixture of
jiotassic iodide with a little boiled starch paste ; the pres-
ence of nitric acid is indicated by a blue color. The re-
agents used should be tested by mixing them together
without the water.

If the water contained nitrous acid^ it will give a blue
color with potassic iodide and starch paste alone.

Quantitatiye estimation.— a. Of the numerous meth-
ods of determining nitric acid, that of Schlossing has
proved the most satisftictory in all cases. Friihling and
Grouven have simplified Schlossing's apparatus somewhat.
{Die landwirthschaftlichen Yersuchs-Stationen^ 9, 13.)

The dissolved nitrate is introduced into the flask A, of
about 400 c.c. capacity, whose mouth can be perfectly
closed by a rubber cork, through which passes a glass

90

62.

BASES AND ACIDS WITH REAGENTS.

tube, a ; the rubber

tube ho should be about 8 cm. long,

and have a clamp on it ; d is another narrow caoutchouc
tube, 15 cm. long. The neck of the jar B is ground on
the outside so that a rubber tube slipped over it will
more readily make a tight joint ; a small glass tube, g^
is connected with the jar by the stop-cock h and rubber
tubing ; another glass tube, /, bent at an obtuse angle, and
reaching above the level of the stop-cock ^, is fastened in
the tubulure m of the jar by a good cork. TJiis last-
mentioned tube being in place, open the stop-cock h^ pour

a little boiled
water into the jar
through the tube
/, and then pour
in mercury until
it rises to the
lower rim of the
rubber tube f on
the neck of the
jar ; close the
stop-cock, put the
jar in the mercury
troutrh so that
the mercury rises
above the tubulure, and remove the glass tube I and
the cork ; now, by means of a pipette, the lower end of
which is bent so that it can be inserted in the tubulure,
introduce 50 c.c. of well-boiled rriilk of hme, and then
cover the mercury in the trough with water to the depth
of about 3 cm.

The solution of the nitrate in A, which must be neutral
or alkaline, is boiled down to a small volume, while the
open end of d is immersed in water ; when the bubbles of
gas escaping from A are completely condensed in passing
through the water, showing that all the air has been ex-
pelled from the liquid in A, close the clamp on 5c, and

§ 62.- NITEIC ACID. 91

dip d m a glass containing a solution of ferrous chloride
in hydrocliloii.^ acid, remove the lamp from A, and open
the clamp just enough to allow this solution to flow into
the flask rather rapidly; when about 200 c.c. of the fer-
rous solution have passed in, replace this solution by dilute
hydrochloric acid, and allow three or four portions of this
to flow in also, and thus wash all the ferrous salt out of the
tube ; finally rinse the tube into the flask with a little dis-
tilled water. Now, close the clamp on be, and, without
allowing any air to enter the tube, insert d in the tubulure
of the jar B, replace the lamp under A, immediately open
the clamp> on be, while holding the rubber tube tightly
compressed between the fingers until a pressure is felt
from within ; then remove the fingers and allow the nitric
oxide gas that is generated in the flask to pass into the
receiver B. The reaction is generally tenninated in about
8 minutes ; so long as nitric oxide is escaping it bubbles
up through the milk of lime in B, but as soon as nothing
but water and hydrochloric acid pass over, both are
absorbed by the milk of lime, and the bubbling of the gas
through it ceases.

If the receiver B is filled with gas before all . the nitric
acid in A is decomposed, close the clamp on be, remove
the lamp immediately from under A, take the rubber tube
d out of the tubulure and let it lie in the water over the
mercury, while the receiver is emptied in the manner de-
scribed below ; then fill the receiver again with mercury
and milk of lime as directed above, insert d in the tubu-
lure again, apply heat to A while the tube bo is closed
■with the fingers only, and proceed as before, until the de-
composition of the nitric acid is finished.

When the evolution of gas finally ceases, close be, re-
move d from the tubulure, and proceed to empty the gas
from B. To this end, mount another flask, C, in the same
manner as A was arranged, put about 100 c.c. of distilled
water in it, attach a rubber tube about 12 cm. long to the

92 62. BASES AND ACIDS WITH REAGENTS.

glass tube that passes through the well-fitting rubber cork
in the mouth of the flask, and put a clamp, y, on the end
of the tube. Fasten this clamp open and boil the water
in C until the air is completely expelled from the flask,
and, while steam is still escaj^ing from the end of the rub-
ber tube, slip it over the glass tube </ on the receiver, and
at the same moment open the stop-cock h ; the aqueous
vapor, from the Avater that continues to boil in the flask,
condenses at first in the neck of the receiver and washes
the milk of lime out of the upper part of it and out of
the glass tube ; if any milk of lime is carried into C in'
the operation that follows, the analysis is worthless.

Now, remove the lamp from C, and a current starts in
the opposite direction, which carries the nitric oxide into
C ; the rapidity of the flow can be regulated by compress-
ing the rubber tube between the fingers ; as soon as the
milk of lime in the receiver has reached the rim of the
rubber tube/, close the stop-cock Ti, and conduct 20 or 30
c.c. of pure hydrogen into the receiver, oj^en the stop-cock
and allow this gas to flow into C ; repeat this two or three
times, thus carrying the last traces of nitric oxide from
B to C. Now, close h again and also the clamp y near
this end of the tube, connect the rubber tube Avith a
small gasometer containing oxygen, open the cOck of the
gasometer and the clamp y again, and oxygen will pass
into C and convert the nitric oxide into nitric acid ; when
all the oxygen has passed into the flask that will, close
the gasometer cock, disconnect the rubber tube from it,
and, after about 15 minutes, determine the nitric acid in
the liquid in C by means of the '1^^ standard solution of
soda ; each cubic centimetre of the sodic solution, con-
taining ^Ijp of an equivalent of sodic oxide (Na^O), will
combine with '1^^ of an equivalent of nitric anhydride
N^Oj^, expressed in milligrammes = 5.4 mgr. or 0.0054 grm.

h. Nitric acid may be very conveniently estimated in
nitrates, as, for example, when it is desired to test the

§ 62. NITKIC ACID. 93

purity of nitre or of Chili saltpetre, by its expulsion at a
high temperature by another acid, as silicic or chromic,
that is not volatile at such a temperature.

Fuse a quantity of the salt, free from carbonic acid,
ammonic salts, or organic matter, at the lowest possible
temperature, pour it on a warm porcelain plate, pulverize
the cake, and dry the powder thoroughly ,• then put 2-3
grms. of finely powdered quartz in a platinum crucible,
and ignite it strongly; add to this about 0.5 grra., care-
fully weighed, of the nitrate prepared as above directed,
mix the two substances carefully with a dry glass rod,
wipe oif the rod with a little more of the quartz powder,
and weigh the whole ; ignite the well-covered crucible
with its contents, for half an hour, at a barely visible red
heat, weigh, and count the loss as nitric anhydride. Sul-
phates or chlorides are not decomposed under these cir-
cumstances, but, if carbonates are present, they must be
removed by previous treatment of the salt with hydro-
chloric acid in slightest possible excess, and evaporation
to dryness on the water-bath.

c. A very convenient method for determining nitric
acid in nitrates is given by C. Noellner. (Fres. Zeitschrift
6, 375), It depends npon the solubility of ammonic nitrate
in absolute alcohol, and the insolubility of other salts of
the alkalies and alkaline earths.

Heat a quantity of the salt containing not more than
0.2 grm. of the nitre with a small quantity of a solution of
ammonic sulphate ; ammonic nitrate is formed, and this
remains in solution while all other salts are precipitated,
when absolute alcohol is added to the liquid ; let the mix-
ture stand a few minutes, filter it, wash the precipitate,
add an alcoholic solution of potassa to the filtrate, collect
the precipitated potassic nitrate on a dried and weighed
filter, wash it with alcohol, dry it at 100°, and weigh it.

94 63. BASES AND ACIDS WITH REAGENTS.

HYDROCHLORIC ACID. IICl. 36.5.

63. Chlorides of all the metals in the list in § 43 are
soluble in water. Plumbic chloride is sparingly soluble
in cold water but readily soluble in hot.

Reaction. — When argentic nitrate is added to a solu-
tion containing a chloride or hydrochloric acid, a white
precipitate is produced, AgCl, which, if at all abundant,
is collected together in curdy flakes on violently agitating
the mixture. This precipitate is blackened on exposure
to the light, is insoluble in dilute nitric acid, but is solu-
ble in ammonia ; from this solution it is re-precipitated
unchanged, on addition of nitric acid in excess. It can
be fused without decomposition. In contact Avith metal-
lic zinc in the presence of sulphuric acid, it is decomposed,
metallic silver being set free.

Quantitative estimation. — Hydrochloric acid or chlo-
rine is most easily and accurately determined by precipi-
tation as argentic chloride, and the estimation may be
made either by a gravimetric or a volumetric process.

a. Gravimetric Process. — Add the solution of argentic
nitrate, containing a slight excess of nitric acid, to the so-
lution of the chloride, heat the mixture and stir or shake
it vigorously to cause the precii^itate to settle more read-
ily, let it stand until the supernatant liquid is quite clear,
decant the liquid through a small filter, agitate the pre-
cipitate with hot water, transfer it to the filter with the
aid of a little water acidulated with nitric acid, wash it
at first with the same acidulated water and afterwards
with pure water, until the washings give no turbidity
with ammonic chloride.

Dry the filter and its contents, separate the latter from
the filter as completely as possible, burn the filter on the
crucible cover, add the ash to the precipitate in the cruci-
ble, heat the whole some time with a little nitric acid, add
a little hydrochloric, evaporate carefully to dryness on the

63. HYDEOCHLOEIC ACID. 95

water-bath, ignite the residue until it begins to fuse, and
weigh it.

When this precipitate of argentic chloride is produced
in the presence of much organic matter, it, together with
the ash of the filter, must be fused with 3 or 4 parts of
pure sodic carbonate, and the fused mass exhausted with
w^ater, the insoluble residue w^ell washed, and the solu-
tions and washings re-precipitated with argentic nitrate,
and the precipitate treated as directed above for washing
and ignition.

The precipitate contains 24.74" \^ of chlorine.

b. Volumetric Process. — To prepare the standard solu-
tion of argentic nitrate, dissolve 18.75-18.8 grms. of
the pure fused salt in 1100 c.c. of distilled water, filter
the solution if necessary, and mix all parts of it well
together.

Weigh out accurately four portions of pure sodic chloride
of 0.1-0.18 grms. each; the salt should have been pre-
viously gently ignited, pulverized while warm, and kept
in a well stoppered bottle until wanted for use.

Dissolve each portion of the salt in 20-30 c.c. of
water, and add 2 or 3 drops of a cold saturated solution
of potassic chromate. Now, allow the solution of argen-
tic nitrate to flow from a burette, graduated into ^1^^ c.c,
into one of these solutions, slowly and with constant stir-
ring ; each drop as it comes in contact w^ith the liquid
produces a red precipitate, which, at first, disappears when
mixed with the. rest of the solution, but finally the addi-
tion of a single drop causes the red color to remain per-
manent ; all the chlorine has united with the silver.

A solution of argentic nitrate is to be made, one litre
of which will exactly precipitate the chlorine in 'L of
an equivalent of sodic chloride expressed in grammes, or
5.85 grms. If the amount of sodic chloride in the solu-
tion tested in this first experiment was 0.11 grm., and

96 63. BASES AND ACIDS WITH REAGENTS.

18.7 c.c. of argentic nitrate were required, we learn by
the proportion,

0.11 : 18.7 = 5.85 : 994.5,

how much of the argentic solution that we liave made
would be required for the desired purpose; we must
therefore add 5.5 c.c. of distilled water to 994.5 c.c. of the
argentic solution, to make a litre of a solution that shall
be exactly equivalent to 5.85 grms. of sodic chloride, or
3.55 grms. of chlorine ; or, since it is more convenient to
measure out one litre of the solution, and add a small
quantity of water accurately measured with the pipette,
we may learn from the projoortion,

994.5 : 4.5 = 1000 : x,
how much water will be required for one litre.

Repeat the test made with one jDortion of the salt with
two of the remaining three portions, keeping the first at
hand as a standard of com23arison, substitute the mean of
the quantities of salt taken and of the three correspond-
ing results in the place of the first and second terms in
the first proportion given above, and make the standard
silver solution accordingly; then, in order to be sure that
the work has been correctly done, rinse the burette out
with a little of the solution last prepared, fill up to the
zero mark with this solution, and make a fourth trial with
the last weighed j)ortion of the sodic chloride. The num-
ber of cubic centimetres of the standard solution required,
multiplied by 0.00585, should give a product exactly equal
to the amount of salt taken.

One cubic centimetre of this solution corresponds to
0.00355 grm. of chlorine.

The solution in which chlorine is to be determined
with the aid of this standard solution must not be acid
in the slightest degree, but should be neutral, or at the
most very slightly alkaline. If strongly alkaline, it should
first be neutralized with nitric acid ; if acid, with sodic

§ 64. HYDROCYANIC ACID. 97

carbonate. Of course, neither of these reagents should
contain any chlorine. Greater accuracy is secured, more-
over, by using the same volume of a solution containing
about the same amount of chlorine as in determining the
standard of the argentic solution in the beginning — that
is, about 25 c.c. containing about 0.15 grm. of chlorine.

It is well, also, to have on hand an accurately titrated
solution of sodic chloride, containing exactly 5.85 grms.
of sodic chloride in the litre, and which, therefore, is ex-
actly equivalent, cubic centimetre for cubic centimetre, to
the argentic solution. Then, if it is feared in any case
that too much argentic nitrate has been added, a cubic
centimetre of this solution can be put in, when the red
coloration will disappear, and argentic nitrate can be add-
ed again more cautiously ; finally, when the desired result
is obtained, subtract one from the number of cubic centi-
metres of argentic solution used.

HYDROCYANIC ACID HCy.

64. Cyanides of manganese, zinc, and copper, are in-
soluble in water.

Reactions* — Cyanides give a white precipitate, AgCy,
with argentic nitrate, insoluble in dilute nitric acid, and
somewhat difficultly soluble in ammonia ; when heated,
it is decomposed, metallic silver being left behind.

If a cyanide is treated with dilute sulphuric acid in a
watch-glass, and another watch-glass, with a drop of
lammonic sulphide charged with excess of sulphur in its
'centre, is quickly inverted over the first glass, the hydro-
cyanic acid evolved from the cyanide is absorbed by the
ammonic sulphide, and on evaporating the drop in the
upper glass to dryness at a very gentle heat, ammonic
sulphocyanate is left, which, if moistened with a drop of
ferric chloride, gives a deep red color.
5

98 65. BASES AND ACIDS WITH REAGENTS.

HTDROFERROCYANIC ACID. HCfy.

65. Ferrocyanides of iron, zinc, manganese, lead, and
copper, are insoluble in water ; ferrocyanides of iron and
copper are insoluble in dilute acids.

Reactions* — Ferrocyanides give a deep blue precipitate
of Prussian blue, FegFe^Cy^g, with ferric chloride, which
is not soluble in dilute hydrochloric acid, but is decom-
posed by sodic hydrate, the blue color being changed to
red.

HYDROSULPHUmC ACID. H^S.

66. Sulphurets of arsenic, lead, copper, iron, manga-
nese, and zinc, are insoluble in water ; the first three are
insoluble in dilute acids.

Reactions. — Sulphurets give with argentic nitrate a
black precipitate, Ag^S, insoluble in dilute nitric acid and
in ammonia.

When sulphurets are treated with hydrochloric or sul-
phuric acid, sulphuretted hydrogen, H^S, is evolved with
efiervescence ; the gas may be recognized by its disagree-
able odor, and the property of blackening lead-paper.

HTDRIODIC ACID. HI.

67. Plumbic iodide is sparingly soluble in cold water,
but readily soluble in hot ; other iodides are soluble.

Reactions. — Iodides give a yellow precipitate, Agl,
with argentic nitrate, which is very sparingly soluble in
ammonia and in dilute nitric acid.

If enough potassic dichromate is added to a solution
of an iodide to give it a pale yellow color, and then a lit-
tle hydrochloric acid, iodine is set free, which, if it is
present in notable quantity, gives the solution a darker

§ 68. HYDIIOFLUOEIC ACID. § 69. OXALIC ACID. 99

color ; a drop of this solution on starch paper colors it
blue ; the latter reaction is very delicate.

HYDROFLUORIC ACID. HF.

68. Calcic and magnesic fluorides are difficulty soluble
in water and acids.

Reactions* — When a fluoride in powder is moistened
with concentrated sulphuric acid, in a leaden or platinum
cup, and gently heated, hydrofluoric acid is evolved ; if
the cup is covered with a piece of Bohemian glass that is
protected with a coating of wax, except along a few lines
where the wax has been removed with a sharp point, the
glass will be corroded on these lines, in a few hours at
the most. If but a small quantity of hydrofluoric acid is
present, the marks may not be seen until all the wax is
carefully cleaned off and the glass is breathed upon.

To be sure that these faint marks are produced by
traces of hydrofluoric acid in the substance, wipe the
glass off carefully with water, and see that they can be
developed again by the breath — and be sure, also, that the
sulphuric acid used does not contain traces of hydroflu-
oric acid, as it sometimes does.

If a silicate is present, this reaction may not take place ;
in this case mix the substance with strong sulphuric acid
in a watch-glass, heat until the mass is dry, and wash the
residue off with water. If fluorine was present, the glass
will be found to be corroded where it came in contact
with the substance.

OXALIC ACID. H2C2O4. 90.

69. Oxalates of barium, calcium, magnesium, iron,
manganese, zinc, lead, and copper, are sparingly soluble,
or insoluble, in water, but soluble in dilute acid.

Reactions. — Oxalates are decomposed, but not black-
ened when heated.

100 § 69. BASES AND ACIDS WITH EEAGENTS.

When an oxalate is heated with plumbic binoxide and
concentrated^ sulphuric acid, a brisk effervescence ensues,
carbonic acid being set free ; if a drop of lime-water, on
the end of a glass rod, is held in the tube above the
liquid, it is made turbid by precipitation of calcic car-
bonate.

A solution of an oxalate in which no free acid except
acetic is present, gives a fine white precipitate, CaC^O^,
with calcic sulphate, insoluble in acetic acid.

Quantitative estimation, — a. Oxalic acid may be ac-
curately determined by a volumetric process with potassic
permanganate.

First make a ^| j„ standard solution of oxalic acid, by
mixing together 10 c.c. of the standard acid already
made and 90 c.c. of distilled water. Put 50 c.c. of this
new standard solution, containing 0.315 grm. of the acid,
in a beaker, add about 100 c.c. of water and 6 to 8 c.c. of
concentrated sulphuric acid, and heat to about 60° C ;
put the beaker on a sheet of white paper and add the
standard solution of permanganate with constant stirring,
in the same manner as directed for the determination of
iron (§ 52). When the reaction is completed, make another
trial with the other 50 c.c. of the ^1^^ standard acid.

The standard of the permanganic solution with refer-
ence to oxalic acid being determined, to estimate the acid
in any substance, whether free or combined, the substance
must be freed from all other compounds that act in the
same manner on the permanganate, such as ferrous oxide,
or organic matter ; dissolve it in water or hydrochloric
or sulphuric acid, add 400 to 500 c.c. of water for every
gramme of oxalic acid supposed to be present, and 6 to 8
c.c. of concentrated sulphuric acid, and proceed to titrate
with the permanganic solution in the usual way. Let
m, = the amount of permanganate used to oxidize 0.315'
grm. of crystallized oxalic acid, or 0.18 grm. of oxalic an-
hydride, and m' the amount required to oxidize the acid

§ 70. ACETIC ACID. 101

in the quantity of substance taken. Then from the pro-
portion,

VYi : 0.18 = m^ : X,
we may learn how much oxalic anhydride, C^Og, was con-
tained in the substance analyzed.

h. Oxalic acid may be estimated in any substance con-
taining it and free from carbonic acid, by converting it
into carbonic acid with the aid of manganic oxide and
concentrated sulphuric acid, and determining this car-
bonic acid. Weigh the substance in the flask A, Fig. 1,
§ 60, add about the same weight of manganic oxide free
from carbonic acid, fill B with concentrated sulphuric
acid, weigh the whole apparatus, and proceed further as
in the estimation of carbonic acid with this form of ap-
paratus (§ 60, a). Each equivalent of oxalic anhydride,
C2O3, yields two equivalents of carbonic anhydride, CO^.

ACETIC ACID. HC2H3O2. 60.

70 • All acetates are soluble in water.

Reactions. — Acetates are blackened when quickly heat-
ed to a high temperature, carbon being set free.

If a neutral acetate is mixed with a solution of ferric
chloride, a deep red liquid is produced ; on boiling the
mixture a red precipitate is formed.

If an acetate is heated with concentrated sulphuric acid
and alcohol in about equal volumes, acetic ether is disen-
gaged, the pleasant aromatic odor of which is best distin-
guished from that of common ether, which may be
formed from sulphuric acid and alcohol alone, after the
liquid has become quite cold.

Quantitative estimation.— Free acetic acid may be es-
timated by a volumetric process, with the aid of the
standard sodic solution.

Since neutral sodic acetate has a slightly alkaline re-
action, it is best to ascertain first, the relation between

102 § '^1. BASES AND ACIDS WITH EE AGENTS.

this Standard solution and one of acetic acid of known
strength. For this purpose add a measured quantity of
the standard sulphuric acid to a solution of sodic acetate,
but not enough to decompose the whole of the acetate.
Each cubic centimetre of the sulphuric acid, containing
0.04 grm., will set free an equivalent quantity of acetic
anhydride, = 0,051 grm., or of the hydrated acid, 0.06 grm.

Knowing, then, how much acid has been set free, we can
titrate the mixture with the standard sodic solution, and
learn how much acetic acid each cubic centimetre of the
sodic solution will neutralize.

Merz recommends the use of a tincture of turmeric as
a coloring matter that is not affected by neutral sodic ace-
tate ; the addition of a single drop of the soda solution to
a solution of sodic acetate colored yellow by this tincture
produces a brown color, while a drop of acetic acid re-
stores the yellow color. ( Wagner's Jahresbericht, 13, 498.)

TARTARIC ACID. Il2C4H40«. 150.

71. Tartrates of barium, calcium, zinc, and copper, are
difficultly soluble in water.

Reactions. — When tartrates are heated, they are black-
ened, and an odor of burnt sugar is given off.

If a solution of free tartaric acid, that is not too dilute,
is mixed with a solution of potassic acetate, a crystalline
precipitate, KHC^II^Og, is formed at once, or after some
time, or after violent agitation, or addition of an equal
volume of alcohol. If the two solutions are very concen-
trated, and are stirred in a watch-glass, a deposition of
crystals marks the track of the rod over the glass.

Calcic chloride gives a white precipitate, CaC^H^Og, in
solutions of a neutral tartrate, the formation of which is
hastened by violent agitation ; the presence of ammonic
chloride only retards the appearance of the precipitate,

§ 72. CITRIC ACID. 103

but does not prevent it. The precipitate is soluble in
boiling soclic hydrate, but re-precipitation follows on
cooling.

With lime-water in large excess, so as to turn red lit-
mus-paper blue, tartaric acid gives the same white precipi-
tate.

With calcic sulphate, tartaric acid in tartrates gives no
precipitate, thus distinguishing it from oxalic acid.

With argentic nitrate, neutral tartrates give a precipi-
tate that is turned black when the mixture is boiled.

Quantitatiyc estimation. — An approximate determina-
tion of tartaric acid may be made by adding potassic
acetate to its moderately concentrated solution, and con-
siderable alcohol, collecting the precipitate on a weighed
filter, washing it with alcohol, and drying it at 100° C,
and weighing.

The residue of potassic tartrate, KHC^H^Og, contains
70.18' |„ of tartaric anhydride, C,H,0,.

CITRIC ACID. H3C6H5O7.

72. Citrates of barium, calcium, and aluminium, are
sparingly soluble in water.

Reactions. — When citric acid is heated, it fuses at first,
and then carbon is separated with the evolution of pun-
gent acid fumes. Citrates are blackened when heated.

Citrates give no precipitate with potassic salts.

With lime-water in excess, at ordinary temperatures,
they give a very slight precipitate, which, on boiling, be-
comes quite abundant, but is mostly dissolved when the
mixture is cooled.

Calcic chloride gives a precipitate Ca^{Cflfi^)^j m
solutions of neutral citrates, which, if obtained without
heat, is soluble in ammonic chloride ; it is re-precipitated
from this solution on boiling, and is not then soluble in
ammonic chloride ; it is insoluble iu potassic hydrate.

104 § 73. BASES AND ACIDS WITH REAGENTS.

MALIC ACID. H2C4H4O5. 134.

73. Malate of lead is difficultly soluble in water
Reactions; — When malic acid is heated, it froths, pun-
gent acid vapors being set free, and crystals of maleic and
fumaric acids are condensed in the colder parts of the
tube.

Malates give no precipitate with potassic salts, nor
with calcic hydrate or sulphate, even on boiling.

With calcic chloride no precipitate is formed unless the
solution is concentrated and the mixture is boiled ; if this
precipitate, CaC^H^O^,2H20, is dissolved in a very little
hydrochloric acid, ammonia added, and the mixture boiled,
the calcic malate is re-precipitated ; but if it is dissolved
in considerable acid, no precipitate is formed on adding
ammonia and boiling ; alcohol will precipitate the salt
from this solution.

Quantitatiye estimation. — An approximate determina-
tion of malic acid may be made by adding calcic hydrate
in excess to its highly concentrated solution, free from
citric, tartaric, or sulphuric acid, and then adding consid-
erable alcohol, collecting the precipitate on a dried and
weighed filter, washing with alcohol, drying at 100° C,
and weighing.

The residue contains 67.44°|q of malic anhydride,
C.H.O..

LACTIC ACID. nCsHsOg. 90.

74. All lactates are soluble in water ; only zincic lactate
is somewhat difficultly soluble in cold water.

Reactions. — Lactates are blackened when heated.

If a liquid containing free lactic acid is boiled with zin-
cic oxide or carbonate, the filtered solution will deposit a
crystalline crust on its surface, or acicular crystals, on
cooling.

§ 75. IJEIC ACID. 105

Quantitatire estimation.— This acid in the free state
may be determined by a volumetric process, the same as
for the determination of acetic acid. The solution, free
from acetic or other free acid except lactic acid, is titrated
with the standard sodic solution. Each cubic centimetre
of sodic solution required corresponds to 0.81 grm. of the
anhydrous acid, CgH^^O^.

To remove acetic acid as well as carbonic from the so-
lution, before estimating the lactic acid, evaporate a por-
tion of the liquid in the water-bath with the addition of
pure quartz sand and with constant stirring towards the
end of the operation ; continue to heat the dry residue
until no more acid odor is given off, then treat it with
water, filter, and wash the sand on the filter as long as the
washings are acid, and determine lactic acid in the filtrate
with the standard sodic solution as above.

URIC ACID. H3CgH2N403 + 4aq. 304.

75. This acid is but slightly soluble in water, and is
insoluble in alcohol. Alkaline urates are soluble in water ;
others are insoluble.

Reactions. — If uric acid or a* urate is heated with mod-
erately strong nitric acid, the mixture filtered if not clear,
the filtrate carefully evaporated to dryness, and the resi-
due moistened with ammonia, a beautiful purple color
(murexide) appears.

In urinary sediments, uric acid may often be recognized
under the microscope by the rhombic six-sided plates, or
right-angled four- sided prisms of a brown to a golden yel-
low color, which it forms.

Quantitative estimation. — ^Precipitate the uric acid
from the solution containing it by the addition of hydro-
chloric acid, if no albumen is present ; in case it is pres-
ent, use acetic or phosphoric acid instead of hydrochloric.
Let the mixture stand 36-48 hours, and collect the pre-

106 76. BASES AND ACIDS WITH REAGENTS.

cipitated acid on a dried and weighed filter, and add 0.045
mgr. to the amount of uric acid found, for every cubic
centimetre of wash-water passed through the filter.

If hippuric acid was present, it must be dissolved out
of this precipitate by treating it several times with alco-
hol of 83" |„.

HIPPURIC ACID. HCsH^NOs. 179.

76. This acid is slightly soluble in cold water, but
readily soluble in boiling water and in alcohol, and slight-
ly soluble in ether.

Ferric and plumbic hippurates are quite insoluble in
water ; all others are soluble.

Quantitative estimation. — Precipitate the concentrated
solution of the acid with hydrochloric acid, and let the
mixture stand in the cold 48 hours ; collect the precipitate
on a dried and weighed filter, wash it with small portions
of very cold water, until the washings are colorless and
give only a faint turbidity with argentic nitrate, dry at
100°, and weigh. For every 6 c.c. of wash-water tliat
passed through the filter add 0.01 grm. to the amount of
hippuric acid found.

If uric acid is present, the precipitate, after being
weighed, must be treated with alcohol, and the residue of
uric acid weighed again. The difference between the two
weights will be the hippuric acid.

For a better method of separating the two acids see
urine, § 113, A.

TANNIC ACID.

77. Tannic acid is soluble in water, alcohol, and ether ;
alkaline tannates are soluble in water, but others are difii-
cultly soluble.

Reactions. — Tannic acid gives a violet-black precipi-

77. TANNIC ACID. 107

tate with ferric salts. It also gives a white precipitate
when poured into a solution of gelatine ; as long as the
gelatine is in excess, this precipitate is soluble in the sn-
pernatant liquor when heated, while if the acid is in ex-
cess, it is much less soluble.

If a piece of fresh skin, deprived of its hair by caustic
lime, is left for several hours in contact with a solution
of tannic acid, the latter is completely absorbed, so that
the liquid will give no color with ferric salts.

Quantitatiyc estimation. — The tannic acid in a solution
may be determined with considerable accuracy by com-
paring the specific gravity of the solution before and
after it has been in contact with j^ow^dered skin.

The solution must be as clear as possible and not too
dilute ; such a one will answer, for example, as may be
obtained by exhausting 20 to 40 grms. of tanner's bark
with water, and diluting to 400 or 500 c.c.

Detei-mine the weight of the extract obtained from a
w^eighed quantity of the bark, and then determine the
specific gravity of the solution accurately with the pik-
nometer, or specific-gravity bottle (§ 34, a). Then weigh
out 100 c.c. of the solution in a flask, and weigh out also
a quantity of finely divided skin, equal to about four
times the amount of tannic acid that is supposed to be in
this quantity of the solution ; this amount can be ascer-
tained approximately from Table lY, taking as the per
cent of tannic acid that which is found against the
number representing the specific gravity of the original
solution, just determined.

Soften the skin by soaking it in -water, enclose it in a
linen bag and press out the water, add it to the weighed
solution in the flask, close the flask and shake the mix-
ture vigorously, filter through a linen cloth and determine
the specific gravity of the filtrate. To the difference be-
tween the specific gravity before and after treatment with
the skin, add one, seek for the number so obtained in the

108 78. BASES AND ACIDS WITH REAGENTS.

column headed specific gravity at 15° C, in Table lY,
and against that will be found the per cent of tannic acid
in the solution examined. A simple calculation will then
give the per cent of the acid in the bark.

To prepare the powder of skin required in this analy-
sis, wash a piece of skin, that has been prepared for
tanning by treatment with lime and other agents, with
water, stretch it on a board, dry it with the aid of a gentle
heat, and rasp it with a coarse file. Keep the powder in
a well stoppered bottle.

CELLULOSE. C12H20O10. 324.

78. Cellulose is insoluble in water, dilute acids or al-
kalies, alcohol, ether, or oils. It is soluble in an ammonic
solution of cupric oxide, and is precipitated from this so-
lution in the form of colorless flakes.

Strong sulphuric acid, composed of four j^arts of acid and
one of water, disintegrates it at ordinary temperatures
without coloring it, and, after a time, changes it into
dextrine. With iodine solution this disintegrated cellulose,
before its passage into dextrine, gives a violet-blue color.

Quantitative estimation. — Cellulose is estimated quan-
titatively by freemg it as completely as possible from all
other substances, and weighing the residue as pure cellu-
lose ; the best method yields results, however, that are
about l^lo too high.

A quantity of 3 to 4 grms. of the substance is exhaust-
ed with water, alcohol, and ether, successively, as long as
each of these solvents takes anything into solution, and
is then macerated 10 or 12 days in a glass-stoppered bot-
tle, at a temperature not above 15° C, with 12 grms, of
nitric acid (Sp. Gr. = 1.1), and 0.8 grm. of potassic chlo-
rate ; water is then added, the mixture is filtered, and
the filter is well washed, first with cold and afterwards
with hot water : the contents of the filter are then rinsed

79. STAKCH. 109

into a beaker and digested about an hour, at 60° C, with
ammoniacal water containing 50 parts of water to one of
common ammonia ; the mixture is filtered through a dried
and weighed filter, the contents of the filter washed with
the same ammoniacal water until the washings are color-
less, then with pure water, with alcohol, and finally with
ether, dried at 100° C, and weighed.

This cellulose often contains as much as from 0.5 to 0.7
" lo of albuminoids, and a very small per cent of inorganic
matters.

STARCH. C12H20O10. 324.

79i Starch, as long as it retains its natural form, is in-
soluble in water, alcohol, and ether. In contact with hot
water the starch grains swell up, and, if a larger quantity
of water is then added, a small portion of the starch re-
mains in solution.

Starch may be converted into a soluble modification by
boiling it with water under pressure, by heating it a short
time with dilute sulphuric acid, or by the action of dias-
tase at ordinary temperatures.

Dry starch is colored blue or black by a solution of
iodine in potassic iodide. The color is destroyed by alco-
hol, potassa, or hydrosulphuric acid, or by heat ; if not
heated too long, the blue color reappears as the solution
cools.

Quantitative estimation. — Starch is usually determined
by conversion into glucose, either by malt or sulphuric
acid, and the subsequent determination of the glucose
with Fehling's solution.

1. By malt. — To prepare the extract of malt, crush 6
grms. of fresh malt in a mortar, digest with lukewarm
water, filter, and wash the filter with water of 60° or 70°,
and divide the clear filtrate, after mixing it well with the
washings, into two exactly equal parts. Mix a quantity

110 79. BASES AXD ACIDS WITH REAGENTS.

of the substance to be examined containing about 2.5
grms. of starch with water, heat to 70° C, add one of the
portions of the extract of malt, put the other portion into
another flask, and digest both precisely alike 3 or 4 hours
on the water-bath, at a temperature of about 60° or 70°
C. Then bring both liquids to about 200 c.c. by addition
of water, add 20 c.c. of a solution of basic plumbic ace-
tate (§ 24, a) to each, shake vigorously, add water again
until the volume of each liquid is exactly 500 c.c, at a
temperature of nearly 15°, let the mixture stand until tlie
solid matters settle, and then determine the glucose in an
aliquot j^art of each liquid with the aid of the standard
Fehling's solution (§ 81). 10 c.c. of that solution corres-
pond to 0.045 grm. of starch. The two liqujds will con-
tain equal quantities of glucose, produced from the malt ;
therefore, the difference between the amounts of glucose
found in the two, or the corresponding difference between
the amounts of starch, will be the amount of starch in
the substance analyzed.

2. a. ^y sulphuric acid. — ^Dry the substance thoroughly,
and digest a quantity of it, supposed to contain about 2.5
grms. of starch, 2 hours on the water-bath, with 50 times
its weight of a dilute sulphuric acid, containing 1°!^, by
volume of concentrated acid, then filter, and wash the
residue on the filter carefully. This residue is composed
mostly of cellulose. Dilute the filtrate and washings to
200 c.c, add about IG c.c. of concentrated sulphuric acid,
and digest again 7 or 8 hours on the water-batli, at 95°,
or until a drop of the solution gives no blue color with a
solution of iodine. If the solution is highly colored, add
20 c.c. of plumbic acetate, shake vigorously, make the
volume of the liquid up to 500 c.c, let the mixture stand
if it is necessary to clarify the solution, and determine the
glucose in the clear supernatant liquid with the standard
Fehling's solution, 10 c.c. of which correspond to 0.045
grm. of starch (§ 81).

79. STARCH. Ill

The process of previous digestion with a more dilute
acid separates the starch more completely from the cellu-
lose, the former being converted into the soluble modifica-
tion, while the latter remains unchanged. {Krocker.)

h. Wolff's process.— 'Dx^Q^X, 2.5 to 4 grms. of the sub-
stance with 100 c.c. of water, and 12 to 16 drops of con-
centrated acid, 24 hours on the water-bath, then seal the
liquid up in glass tubes and heat 12 hours in an oil-bath to
120° C, then dilute, decolorize with plumbic acetate, and
so on as directed in a,

3. Dragendorff gives the following method for separat-
ing and determining starch and the other matters with
which it is usually associated.

Pulverize about 2.5 grms. of the substance that has been
dried at 100°, mix the powder with about 30 grms. of a
solution of about 6 parts of i3otassic hydrate in 95 parts of
absolute alcohol, and digest the mixture 24 hours at 100° C.
in a sealed tube, or in a flask that can be closed air-tight ;
filter the contents of the flask, while hot, through a dried
and weighed filter, wash the residue thoroughly, first with
hot absolute alcohol, then with cold alcohol of ordinary
strength, and finally with distilled water, mixed with a
little alcohol if gummy substances are present in notable
quantity, dry the filter, first at 50°, and then at 100°, and
weigh. The difference between this weight and that of
the substance taken gives the amount of albuminoids, fat,
sugar, and a part of the mineral salts.

The insoluble residue, with the filter torn in shreds, is
heated with water containing S"!,, of hydrochloric acid
until a drop of the liquid gives no blue color with solution
of iodine, the mixture is filtered ao:ain throuG:h a dried
and weighed filter, dried at 100°, and v/eighed. The sec-
ond loss of weight gives the amount of starch ; it was
converted into dextrine by the acid and dissolved out ;
a very small quantity of mineral matters might pass into
solution also, and, if great accuracy is required, the

112 § 80. BASES AND ACIDS WITH REAGENTS.

amount of these can be determined by evaporating the
solution of starch and inorganic salts to dryness, and in-
cinerating the residue at a low red heat (§ 91).

Or, the starch may be extracted with a concentrated
solution of malt instead of with acid, in wliich case no in-
organic salts will be taken into solution. Prepare the
solution of malt and perform the operation as directed
above.

If much mucus is present, a concentrated solution of
sodic chloride mixed with 6°\^ of hydrochloric acid should
be used instead of pure water and acid.

GUM.

80. The gums, which abound in the juices of plants,
are very soluble in water, forming thick, viscid solutions ;
they are insoluble in alcohol.

Quantitative estimation. — This depends upon their in-
solubility in alcohol. A quantity of from 500 to 1000 c.c.
of the aqueous extract of the substance in which the gum
is to be determined is evaporated almost to dryness on
the water-bath, and the moist residue is digested with al-
cohol of 80 to 85" |„ until it is no longer colored by mat-
ters taken into solution.

Sugar is dissolved, while gum, albuminoids, and some
inorganic salts, remain unaffected ; collect the insoluble
substance on a dried and weighed filter, dry at 100° C,
and weigh. Then incinerate this residue at a low red heat
(§ 91), and subtract from the total weight of the residue
insoluble in alcohol, the sum of the weights of the ash
just determined, and the albuminoids, which are deter-
mined by another process (§ 85). The remainder may be
considered as gum, mixed with some vegetable acids.

GLUCOSE. GRAPE SUGAR. CeHi^OeHaO. 180 + 18.

81 . This sugar is soluble in water, and somewhat solu-
ble in aqueous alcohol.

§ 81. GLUCOSE. 113

It is colored dark brown when heated with a strong so-
lution of sodic hydrate.

If triturated Avith cold concentrated sulphuric acid, it
is dissolved without being blackened.

If a concentrated solution of glucose is mixed with co-
baltic nitrate and a small quantity of fused caustic soda,
the solution remains clear on being boiled.

If baric hydrate is added to an alcoholic solution of
sugar, a white precipitate is formed.

If a little caustic soda is added to a solution of glucose,
and then, drop by drop, a dilute solution of cupric sul-
phate, a deep blue liquid is formed ; but after a few mo-
ments a yellowish or red precipitate of hydrated cuprous
oxide is separated. A solution containing 0.00001 of glu-
cose will give a notable red precipitate on the addition of
soda and a few drops of cupric sulphate ; 0.000001 of glu-
cose in the solution gives a red tint to it with the above
reagents.

Quantitatiye estimation. — This may be effected by
making use of the delicate reaction just described. One
equivalent of glucose will reduce ten equivalents of cupric
oxide to cuprous oxide ; if, then, we know the quantity
of cupric oxide that has been reduced, we can calculate
the corresponding amount of sugar. For this determina-
tion, a standard solution of cupric oxide containing an
excess of alkali is commonly used, or Fehling's solution,
as it is often called.

Dissolve 34.639 grms. of pure, crystallized cupric sul-
phate in about 200 c.c. of water ; make another solution
of 173 grms. of pure, crystallized potassic sodic tartrate
in 480 c.c. of a solution of sodic hydrate (Sp. Gr. = 1.14).
Add the first solution gradually to the second, and dilute
the mixture to 1000 c.c. Each 10 c.c. of this solution
corresponds to 0.05 grm. of glucose. Keep the solution
in small, well-stoppered bottles, in a dark place ; the bot-

114 § 81. BASES AND ACIDS WITH REAGENTS.

ties should be filled to the top, so that no carbonic acid
can be absorbed.

Before using the solution, boil about 10 c.c. of it with
about 40 c.c. of water, or of a dilute solution of sodic hy-
drate if there is any reason to believe that carbonic acid
has been absorbed ; there should not be the least change
in the liquid when subjected to this trial.

To perform the analysis, put 10 c.c. of the cuprlc solu-
tion in a porcelain dish, and add 40 c.c. of water, or of a
solution of sodic hydrate if it was found necessary to
add this in testing the solution ; heat the mixture until it
boils gently, and allow the sugar solution, which should
be colorless and not acid, and should not contain more
than ^1^ to ^|/|g of sugar, to drop in from a burette or a
pipette, graduated into ^\^^ c.c, so slowly that the boiling
will not be stopped. After the addition of the first few
drops, the fluid shows a greenish-brown tint ; as more sug-
ar solution is added, the precipitate becomes more copi-
ous, acquires a reddish tint, and subsides more speedily j
when it presents a deep red color, remove the lamp, allow
the precipitate to settle, and give the dish an inclined
position, so that the color of the supernatant liquid can
be more readily distinguished over the white porcelain
surface ; if no blue or bluish-green color is seen, probably
enough of the solution of sugar has been added. To be
sure, test a small portion of tbe clear liquid with a drop
of the solution from the burette ; if a yellowish-red
precipitate appears on heating, which, at first, may
look like a cloud in the liquid, pour the contents of the
tube back into the dish again, and continue to add the
sugar solution until the reaction is completed. Then
the solution in the dish should contain neither copper nor
sugar, nor a brown product resulting from the decompo-
sition of the latter ; filter ofl* a portion of it while still
hot ; the filtered liquid should have no brown tinge ; one
portion, heated with a drop of the standard cupric solu-

§ 82. LEYULOSE. § 83. SACCHAROSE. 115

tion, should produce no change in it ; another poition
should give no red coloration or precipitate with potassic
ferrocyanide. nor a black one with amnionic sulphide. If
these tests do not indicate a satisfactory termination of
the analysis, it should be repeated with a fresh quantity
of 10 c.c. of the cupric solution.

The amount of solution of sugar required to reduce the
cupric oxide in this quantity of the cupric solution con-
tained 0.05 grm. of glucose.

Generally, the first result obtained is only an approxi-
mation ; in the second trial, add at once nearly the whole
amount of sugar solution required, and then test the liquid
after each addition of two drops at a time. {Fresenius.)

LEVULOSE. FRUIT SUGAR. CeHi^Oe.

82* This sugar is Tery soluble in Avater and aqueous
alcohol. It behaves like glucose with an alkaline cupric
solution, and is determined quantitatively in the same
manner.

SACCHAROSE. CANE SUGAR. C12H22O11. 342.

83. This sugar is more soluble in water and aqueous
alcohol than glucose.

It is not turned brown by strong alkaline solutions.

If triturated with cold concentrated sulphuric acid, it
is turned black, and sulphurous acid is evolved.

If a concentrated solution of saccharose is mixed with
cobaltic nitrate and a small quantity of fused caustic
soda, and boiled, a violet-blue precipitate is formed. The
presence of a very small quantity of glucose prevents the
formation of this precipitate.

If sodic hydrate is added to a solution of saccharose,
and a few drops of cupric sulphate, a deep blue solution
is obtained that remains unchanged on standing in the
cold ; if the sodic hydrate is largely in excess, the solution
can be boiled a short time without change.

116 § 84. BASES AND ACIDS WITH EKAGENTS.

Saccharose is converted into glucose and levulose when
heated with very dilute sulphuric acid, by treatment with
yeast, or even by long boiling of its aqueous solution alone.

Quantitatiye estimation. — This may be effected by first
converting the saccharose into glucose and levulose, and
then determining the amount of these with the standard
cupric solution.

The solution, containing about 2.5 grms. of saccharose,
is diluted to about 250 c.c, 12 drops of concentrated sul-
phuric acid are added, and the mixture is heated 3 hours
on the water-bath, with renewal of the water as it is
evaporated (§ 36). If, after this operation, the solution
has a dark color, as may often be the case, add 20 c.c. of
the solution of j)lumbic acetate (§ 24, a), shake the mix-
ture well, dilute to exactly 500 c.c, let it stand awhile,
and use the clear supernatant liquid for the determination
of glucose (§ 81).

If it does not need clarifying with plumbic acetate, neu-
tralize the free acid with sodic carbonate, dilute to exactly
500 c.c, and determine glucose as above.

10 c.c. of the standard cupric solution correspond to
0.0475 grm. of saccharose.

In case a solution contains both glucose and saccharose,
and it is desired to determine the amount of each, esti-
mate the glucose at once by titration with the cupric so-
lution ; then convert the saccharose into glucose, as above,
and titrate the solution again ; the last determination
gives the sum of the glucose originally in the solution
and that which was derived from the saccharose.

LACTOSE. MILK SUGAR. CasHaiOja.

84. This sugar is soluble in water, but not in cold
alcohol.

It reduces an alkaline solution of cupric oxide like glu-
cose, but in a different proportion. It is converted into
glucose by dilute acids.

§ 85. ALBUMINOIDS OR PROTEIN COMPOUNDS. 117

Quantitative estimation. — Convert it into glucose by
digesting its solution about 2 hours with a little sulphuric
acid, and then determine the glucose with the standard
cupric solution.

10 c.c. of the solution correspond to 0.05 grm. of
lactose.

ALBUMINOIDS or PROTEIN COMPOUNDS.

85. Some of these substances are soluble in water,
others are insoluble. Most metallic salts precipitate them
from their solutions, or coagulate the solutions, as it is
termed.

All of them are dissolved by boiling concentrated hy-
drochloric acid, and the solution takes a violet color if
access of air is allowed.

All of them are colored yellow by concentrated nitric
acid, and by iodine.

They are colored red by a solution of mercuric nitrate
(Millon's test) ; this is the most delicate test for these
bodies ; albumen, dissolved in 100,000 parts of water,
may be detected by this reagent.

If a small quantity of an albuminous substance is treat-
ed with dilute potassic hydrate, one or two drops of a
dilute solution of cupric sulphate added, and more potassa
until the mixture is alkaline, and the whole is well mixed
together, a violet precipitate appears, which dissolves after
a little agitation ; in the presence of a carbo-hydrate, as
sugar or starch, the color is bluish, and the blue tint is
deeper, the more of the carbo-hydrate is mixed with the
albuminoid. {Journal far Frakt. Chemie, 102, 376.)

When heated, these substances give off the odor of
burnt horn or hair.

Distinctive reactions.— ^^S^^^e^ is precipitated when
its neutral solutions are heated to 70° C, or the solution is
coao-ulated ; if alkaline, the solution needs to be neutral-

118 § 85. BASES AND ACIDS WITH EE AGENTS.

ized by acetic acid before this reaction can be obtained ;
if the solution is very dilute, the presence of albumen
will be shown by a flocculent precipitate, or a mere tur-
bidity, on being boiled. A solution of albumen is coagu-
lated also by plumbic acetate or cupric sulphate, but not
by acetic acid.

Casein is not precipitated from its solutions by heat,
except that a film is formed on the surface of the boiling
liquid ; it is precipitated by acetic and other acids, and
the precipitate is soluble in an excess of acetic acid.

Fibrine is precipitated from its solutions spontane-
ously, when they are removed from the influence of vital
forces.

Quantitative estimation. — As it is almost impossible to
separate all of an albuminoid from its solution or from
matters mixed with it, pure and unaltered, or in the form
of any insoluble precipitate of a definite composition, the
amount of albuminous matters in a substance is usually
estimated froiji the amount of nitrogen in it.

Albuminoids contain, on an average, 16° 1^ of nitrogen;
therefore, the total weight of the albuminoid is VV — 6.25
times that of its nitrogen. Assuming, then, what is gen-
erally true, that all the nitrogen present in the dried
plant is part of an albuminoid, we multiply the weight
of nitrogen found in the substance by 6.25 for the weight
of the albuminoids.

Determination of Nitrogen. — The method most gener-
ally applied in this case, as well as in agricultural analyses
generally, is that of Yarentrapp and Will, as modified by
Pehgot, in which the nitrogen is converted into ammonia
by ignition with soda-lime, and the ammonia is absorbed
by a measured quantity of a standard acid ; the ignition
is performed in a thick-walled tube of hard Bohemian
glass, about 40 cm. long, and 12 mm. in diameter, drawn
out into a slender beak at one end that is bent upwards.

§ 85. DETERMINATION OF NITROGEN. 119

a. First clean and dry the tube thoroughly, and seal up
the point of the beak ; then put in the throat, where the
beak widens out into the tube, a loose plug of freshly ig-
nited asbestus ; rinse the tube out with a little soda-lime,
about half fill it with the same reagent, freshly io-nited
and still warm, empty this soda-lime into a warm, dry
mortar, and mix intimately with it, by gentle trituration,
without much pressure, a carefully weighed quantity of
from 0.2 to 0.5 grm. of the finely powdered and well- dried
substance ; the quantity to be taken depends upon the
richness of the substance in nitrogen ; fill about 3 cm. of
the tube with soda-lime, and transfer this mixture into it
from the mortar, by scooping it up carefully with the
open end of the tube, over a sheet of dark-colored glazed
paper ; carefully rinse the mortar and pestle into the tube
with several small portions of the soda-lime, and finally,
when the tube is filled to within about 4 cm. of the end,
close it with another plug of freshly ignited asbestus, and
rap it gently on the table several times, in order to se-
cure an open space in the upper part of it for the passage
of gases.

h. In some cases, as in the analysis of Peruvian guano
for example, the evolution of ammonia is liable to begin
as soon as the substance and soda-lime are brought to-
gether. If there is danger of this, fill about 10 cm. of
the tube with soda-lime, which should be but very slightly
warm, if at all, then put in the substance, fill 10 cm. more
with the reagent, and mix the two together as rapidly as
possible by means of a wire, bent in the form of a cork-
screw at the end ; if this is moved backwards and for-
wards, and twisted round a few times, through the sub-
stance and the soda-lime, a very perfect mixture can be
quickly made ; before taking the wire out, put in about
10 cm. more of soda-lime, and work the corkscrew back
and forth through this to clean it, and then fiinish filling
the tube as in a.

120

85.

BASES AND ACIDS WITH REAGENTS.

With the aid of the burette, put 20 c.c. of the standard
sulphuric acid in the bulbed tube C (fig. 5), and add
water until the bulbs are about 'I3 filled ; the quantity of
the liquid should not be so great, however, as to incur any
danger of loss when the gases evolved from the combus-
tion-tube pass rapidly through, or when, as sometimes
B A

Fig. 5.

happens, there is a sudden retrograde current towards the
combustion-tube at the close of the operation.

When the bulbed tube is properly filled, hold it so that
the liquid rises higher in one arm than in the other, con-
nect it with the combustion-tube by the soft, well-fitting
cork, that has been already fitted to the small horizontal
tube of the bulbed apparatus, and lay the combustion-
tube on a level table ; if the connection is not tight, the
acid will slowly assume the same level in both arms of
the bulbed tube.

The apparatus being tight throughout, and a small fur-
nace full of live charcoal coals being ready, the combus-
tion-tube is introduced into the iron combustion-furnace
(fig. 5), so that only about 5 cm. of the tube remains out-
side the furnace at B, and the whole is slightly inclined
towards that end, so that any water, condensing in the
small tube of the bulbed apparatus, will flow down into
the bulb beyond.

A movable screen benig placed over che tube in the
fm-nace, about 8 cm. from the end B, this end is surround-

§ 85. DETEEMIITATION OF NITEOGEN. 121

ed with fresh, live coals, large coals being used to brido-e
over the top, in order that there shall be no weight there
on the tube Avhen softened by heat, to bend it inwards
and close the passage above the soda-lime.

When this part of the tube is red-hot, move the screen
along about 8 cm., and apply more coals in the same man-
ner as around the first 8 cm. of the tube.

When that part of the tube is approached, where the
mixture of soda-lime and substance is contained, care
must be exercised in applying the coals, so as not to have
too rapid an evolution of the gas ; there is little danger
that any ammonia Avill pass through the acid unabsorbed,
but it will be safer not to have so rapid a flow of gases that
the bubbles in the bulbed apparatus cannot be counted ;
nevertheless, a continuous current should be maintained,
and, all the while, the front end of the tube must be kept
well heated by supplying fresh coals as often as is nec-
essary.

When the tube has been heated throughout, and quite
intensely around the mixture of substance and soda-lime,
and the passage of bubbles through the acid has ceased,
break oif the point of the beak at A, and draw a consid-
erable quantity of air through the whole apparatus by
applying suction at the mouth of the bulbed tube, in or-
der to carry all ammonia remaining in the combustion-
tube into the acid ; disconnect the bulbed tube from the
other, add a little cochineal, and then the standard sodic
solution until the acid is almost neutralized, empty the
contents of the bulbs into a beaker, rinse with a little
water, and finish the titration (§ 45).

For each cubic centimetre of the acid that was neutral-
ized by the ammonia set free, the substance analyzed con-
tained 0.014 grm. of nitrogen.

When very great accuracy is required, the ammonia
should be collected in hydrochloric acid, oily matters fil-
tered out, if any are seen in the acid after the combustion
6

122 § 88. BASES AND ACIDS WITH REAGENTS. .

is finislied, the bulbs rinsed out with alcohol, and the am-
monia determined with the aid of platinic chloride (§ 47, a).
If the substance is very rich in nitrogen, it must be
mixed with an equal quantity of j^ure sugar, in order to
avoid the danger of an impetuous retrograde current in
the bulbed tube, when the evolution of gas ceases and
the whole apparatus is filled with ammonia-gas.

UREA. CH4N0O. 60.

86i Urea is very soluble in water and alcohol, but dif-'
ficultly soluble in ether.

Reactions! — -When heated it gives off ammonia.

Nitric or oxalic acid causes the formation of a white
precipitate in concentrated solutions of urea.

Quantitative estimation* — The volumetric method of
Liebig, with mercuric nitrate, is easily and quickly exe-
cuted and yields accurate results.

To prepare the standard solution of mercuric nitrate,
heat an excess of mercury with concentrated nitric acid,
concentrate the solution, and, on cooling, crystals of mer-
curous nitrate will be deposited ; pour off the mother-
liquor, wash the crystals, first with dilute nitric acid, and
then with cold water, dissolve them in pure nitric acid,
and heat the sohition until a drop of it gives no precipi-
tate or turbidity with sodic chloride ; evaporate the solu-
tion on the water-bath to the consistency of a syrup, dilute
it with 10 volumes of Avater, let it stand 21: hours, and
filter if any precipitate is formed.

To determine the strength of this solution, dissolve
10.864 grms. of pure, ignited sodic chloride in 1 litre of
water; dilute 10 c.c. of the mercuric solution with 90
c.c. of water, put 10 c.c. of this diluted solution in a small
beaker, add 4 c.c. of a cold saturated solution of sodic
phosphate, and quickly, before the precipitate caused by
this reagent has time to become crystalline, allow the so-

§ 86. UKEA. 123

lution of sodic chloride to flow in from a burette with
constant stirring, until the precipitate disappears, and the
solution becomes clear again. Each cubic centimetre of
the sodic solution required corresponds to 0.02 grm. of
mercuric oxide ; on the basis of this determination, then,
the amount of mercuric salt in the diluted solution, and
the strength of the concentrated solution, can be estimated.

Now, to bring the mercuric solution to a urea standard,
it must be diluted so that 1 litre will contain 72 grms. of
mercuric oxide ; dilute the solution almost to this point,
and then compare it with a solution of urea of known
strength. For this purpose, dissolve 2 grms. of pure
urea, dried at 100° C, in water, dilute the solution to 100
c.c. and put 15 c.c. of this solution in a beaker; in an-
other small beaker, wash a few crystals of sodic bicar-
bonate with a considerable quantity of cold water, and,
after pouring this oif, add just enough water to make a
thin paste with the salt ; have ready also a piece of clean
glass, with its under surface coated with asphaltum varnish.

Now, allow the mercuric solution to flow slowly from
the burette into the solution of urea, with the addition
from time to time of a small quantity of dry sodic car-
bonate, in order to nearly, but not quite, neutralize the
nitric acid that is set free ; the solution must all the while
have a slight acid reaction. To ascertain whether all the
urea is precipitated, transfer a drop of the solution, on
the end of a glass rod, to the glass plate, and cover it
with a drop of the paste of sodic bicarbonate ; if no yel-
low color appears in a few seconds, wash the test-drop
back with the smallest possible quantity of water, and,
after adding a little more mercuric nitrate, test again with
the sodic bicarbonate ; the first trace of a yellow color,
that appears as soon as the two drops come together, in-
dicates that sufficient mercuric chloride has been added.

The standard mercuric solution is to be diluted so that
1 cubic centimetre corresponds to 10 mgr. of urea, or to

124 § 86. BASES AXD ACIDS WITH REAGENTS.

0.5 c.c. of this solution of urea of known strength that
has been prepared.

M. Byasson ( Chemical JVews Amer. Itepr.^ 4, 143) pre-
pares this standard solution by dissolving exactly 72
grms. of pure red oxide of mercury, or mercuric oxide, in
100 grms. of nitric acid diluted with half its weight of
water, evaporates the solution at a gentle heat until acid
vapors appear, and then makes the volume up to one litre
at 15° C; if the dilution causes a slight turbidity, a few
drops of nitric acid will remove it. In this way, he states,
a solution will be obtained in which all the mercury is
present as mercuric nitrate, and with as small an excess of
acid as possible ; while, if prepared by dissolving mercury
in nitric acid, it is liable to contain mercurous nitrate.

As this mercuric solution is also to be used, in anal-
yses of urine, to determine the sodic chloride, it should
also be titrated with reference to this. Take 10 c.c. of a
solution of sodic chloride containing 2"]^ of the salt or 0.2
grm., add to it 3 c.c. of the standard solution of urea,
prepared as above, and 5 c.c. of a cold saturated solution
of pure sodic sulphate, and allow the mercuric solution
to flow from the burette into this mixture with constant
stirring, until there is a permanent turbidity in the liquid ;
the amount of mercuric solution required for this corres-
ponds to the 0.2 grm. of sodic chloride ; calculate the
amount of sodic chloride that corresponds to 1 c.c. of the
standard mercuric solution, and mark it on the label of
the bottle.

For the determination of urea in a solution containing
it and free from phosphoric and hippuric acids, proceed
with 15 c.c, as directed for determining the standard of
the solution with reference to urea, after having first de-
termined the sodic chloride, which is commonly present,
by the amount of the standard solution required to pro-
duce permanent turbidity ; use the dry sodic carbonate to
maintain the neutrality of the solution, the paste of the

§ 87. FATTY SUBSTANCES. 125

bicarbonate to ascertain the point of saturation with mer-
curic chloride, and so on in the manner already described.

The results obtained, however, must be corrected for
very dilute or very concentrated solutions of urea, since
the standard mercuric solution is adapted for such solu-
tions only as contain 2° |^ of urea ; if the solution is more
concentrated than this, the yellow color appears prema-
turely ; if more dilute, it does not appear so soon as it
should.

If the reaction indicating saturation was obtained with
10 c.c. or less of the mercuric solution, subtract the prod-
uct of 0.08 into the whole number of cubic centimetres re-
quired, from this total quantity ; if the reaction was obtain-
ed with less than 15 c.c. but with more than 10 c.c, subtract
also, in addition to the above product, the product of 0.06
into the number of cubic centimetres required above 10 ;
if more than 15 c.c. were required, but less than 20, sub-
tract also, from the total amount used, the product of 0.04
into the number of cubic centimetres above 15, in addi-
tion to the above two products. (RcCutenherg, Fres. Zelt-
schrift, 4, 500.) The final remainder, multiplied into 0.01,
will give tlie amount of urea in the 15 c.c. of solution
tested.

In case the solution is more than 2"! ^ strong, then more
than 30 c.c. of the standard mercuric solution will be re-
quired ; for each cubic centimetre of the standard solution
used above 30 c.c, ^l^ c.c of water must be added to the
mixture, before taking out a sample dro^) to be tested
with the paste of sodic carbonate.

FATTY SUBSTANCES.

87i Fats are insoluble in water, somewhat soluble in
strong alcohol, and very soluble in ether.

Quantitatiye estimation. — This is effected by heatmg
the finely divided substance with 2-3 volumes of ether

/
126 § 88. BASES AND ACIDS WITH REAGEISTS.

(Sp. Gr. rr 0.72), evaporating tlie etherial solution of fat to
dryness, and weighing the residue.

Several portions of ether must be used, and the extrac-
tion is best conducted in a flask "^^ovided witli tubes like
a washing-bottle, and which is connected with the lower
end of a Liebig's condenser (§ 36).

The extraction may not be considered as ended until a
drop of the last filtrate leaves no residue when evaporat-
ed on a watch-glass. The solutions, if not perfectly clear
as they came from the filtering flask, should be filtered
through paper. The chlorophyll in the green parts of
plants goes into solution Avith the fat, but it may be re-
moved by filtration thi'ough bone-black.

The clear etherial extracts may be collected in a gradu-
ated cylinder, and the fat determined in an aliquot part of
the well-mixed liquid by evaporation to dryness, drying
the residue at 100° C, and weighing.

ALCOHOL. CsTIeO. 46.

88 • Alcohol is miscible with water in all proportions.

QuantitatiYC estimation. — This is eflfected by distilling
the alcohol ofi", and estimating it in the distillate by the
specific gravity.

a. To 10 c.c. of the solution to be examined, which
must contain no free A'^olatile acid, as acetic, for example,
add its volume of water, and subject the whole to distill-
ation in a small flask connected with a small Liebig's
condenser. Collect the distillate in a specific-gravity bot-
tle with a mark on it, indicating a capacity of 10 c.c.
When somewhat less ^ than half the liquid has been dis-
tilled over, remove the specific-gravity bottle from the
tube of the condenser, bring the temperature of the dis-
tillate to 15° C.,fill up to the mark with water, and weigh.
Knowing the weight of 10 c.c. of water at this tempera-

§ 88. ALCOHOL. 127

ture (weight of 1 cubic centimetre = 0.999183 grm.), we
can calculate the specific gravity of this distillate, that
contains all the alcohol that was in the liquid examined,
and from Table Y, learn the per cent of alcohol in the
distillate. Then the per cent of alcohol by weight in the
solution examined is readily calculated if the weight of
10 c.c. of that solution is known.

Griffin, in his examination of wines {J. J'. Griffin,
Gheinical Testing of Wines and /Spirits), used 25 c.c.
of the alcoholic liquid, added its volume of water to it,
made the volume of the distillate up to 50 c.c, and deter-
mined its specific gravity.

If the substance to be examined contains free acetic
acid, add a little soda to the liquid before distillation.
The distillate should have no acid reaction.

b. The alcohol in a wine may be approximately esti-
mated by evaporating a measured quantity to about half
its bulk, adding water until the original volume is re-
stored, and determining the specific gravity of this liquid;
then subtract the number by which this specific gravity
is greater than one, from the specific gravity of the alco-
holic liquid itself, and take the remainder as the specific
gravity of the mixture of alcohol and water in that liquid,
and get the per cent of alcohol corresponding to this
specific gravity from Table V. To illustrate the principle,
suppose a wine is examined whose specific gravity equals
0.9951 ; after evaporation down to one-half, and adding
water until the original volume is restored, the specific
gravity is 1.0089.

0.9951 — 0.0082 = 0.9869.

Against the specific gravity of 0.9862 in the table, the
per cent of alcohol is found to be 8.

128 § 89. SPECIAL METHODS OF ANALYSIS.

CHAPTER lY.

Special Methods of Analysis.
1.

COURSE OF QUALITATIVE ANALYSIS.

89. The following course of analysis is designed as
a general guide in qualitative analytical work. Only a
single reaction for each substance is mentioned in it, and
that is generally the most delicate one ; for fuller de-
tails in regard to this particular reaction, and for a few
other ones that may in some cases be applied as confirma-
tory tests, the student is referred to Chapter III.

He should, before undertaking to work with the aid of
this course, thoroughly familiarize himself, by actual ob-
servation, with the behavior of the different acids and
bases with reagents, so that he may know what is indi-
cated by any particular reaction, the moment he sees it.

The mode of working with the aid of the scheme given
below is best explained by an example. Suppose we have
a solid containing CI, P20^, SO3, K,Fe, and Mn. Begin-
ning with 1 in the left-hand column of figures, in the course
for the detection of the acids, the first question is,
whether the substance is a soJid or a solution. It being
the former, we are referred, in the right-hand column of
figures to 2 ; going then to 2, in the left-hand column,
we find that the solubility of the substance is to be test-
ed ; we apply the solvents in the order there indicated,
and find that it is soluble in dilute nitric acid, when wo
are referred to G ; going to 6, in the left-hand column, we
get no gritty residue on evaporation to dryness, and there-
fore no silicic acid is present ; passing on to 7, to which
we are referred next, we get no such reaction as is de-

§ 89. COUKSH OF QUALITATIVJa ANALYSIS. 129

scribed there, nor such ns in 0 ; therefore, carbonic acid
and sulphur are absent ; we do get, however, the fine
white precipitate as described in 9, and note sulphuric
acid as present; we also get a yellow precipitate in 10,
and make a note of phosphoric acid as present ; we do
not get the reaction in 11, but get a white precipitate in
12, the formation of which, under the circumstances, indi-
cates that cyanogen, iodine, ferrocyanogen, or chlorine,
may be present ; a precipitate would be given also by
sulphur, if that were present, but the test for this element
has already been made ; we do not find the first three
substances named above, and learn in 16 that, consequent-
ly, chlorine is present ; we find no nitric acid in 17, and,
as the substance is not blackened when heated as directed
in I85 no organic acids are present, and wo have finished
the examination for the acids.

Passing to the detection of the bases, we have the
question in 1 already answered for us, with this small
difierence, that, in the examination for the bases, a hydro-
chloric-acid solution is preferable to a nitric-acid solution ;
going on to 3, we add sulphuric acid, and get no reaction,
even after the mixture of substance and reagent has stood
some time ; no lead or barium, and, at the most, only
traces of calcium, can be present ; passing on to 7 we find
no ammonium; we get the violet color, indicating potas-
sium, in 9, after having properly prepared the solution as
directed in 8 ; and so working on, we find no copper in
10, but do get iron in 11, and manganese in 15, and after
that, nothing more before reaching the end of the course.

It will be noticed that sulphuretted hydrogen and am-
monic sulphide, and also the blowpipe, are used but little
or not at all in this course of analysis ; there are suffi-
ciently good reasons why their use should be dispensed
with, if it can be done without impairing the reliability
of the work.

The plan of the course for the bases corresponds in the
6*

130 SPECIAIi METHODS OF ANALYSIS.

main witli that of Zettnow. {Poggeyidorf^s Annalen^
103, 324.)

The attention of the analyst is called to Table X,
where the average and extreme composition of agricul-
tural materials and products are given ; by consulting
this table he can ascertain what he may expect to find in
any substance under examination, that is used in, or
produced by, agriculture, and whether or not he must
needs work with special care, or with large quantities of
the substance, in order that a small quantity or traces of,
any element or compound shall not escape detection.

A,

DETECTION OF ACID ELEMENTS AND ACIDS.

1. a. The substance is a solution ; this solution will
be referred to as th.Q first solution, - - . . 6
h. Not a solution. - - - - - - 2

2. a. The substance is soluble in water, or in dilute
or concentrated nitric or hydrochloric acid ; this
solution will be referred to as the^rs^ solutlo7i. - 6
h. It is partially soluble in water or acids, as indi-
cated by the residue left undissolved even after
heating, and by the distinct residue left on evapo-
ration of a drop of the solvent with which the
substance has been treated. Treat a larger portion

of the finely divided substance with another por-
tion of the solvent, filter, and mark the filtrate F 2.
With the contents of the filter go to - - - - 3
c. It is quite insoluble in water or acids. - - - 3

3. A portion of the insoluble substance, in the shape
of a very small fragment, if possible, rather than
a fine powder, is fused for a considerable time in a
bead of phosphorus-salt on platinum wire ; the

DETECTIOX OF ACIDS. 131

fragment is not entirely dissolved, but remains
visible in the bead, retaining its original form.
Also, Avhen the substance in powder is fused in a
bead of sodio carbonate on the platinum wire, the
bead froths, carbonic acid being set free. Both
these reactions together indicate Silicic. - - - 4

4. A small portion of the original substance, finely-
pulverized, is made into a paste with concentrated
sulphuric acid in a leaden tray, the tray is covered
with a piece of Bohemian glass coated with wax,
and from which the coating has been removed in
a few places with a sharp-pointed instrument, and
the whole is gently heated for about a half an
hour. The glass is found to be corroded where
the wax was removed (see § 68). Fluorine. - 5

5. The insoluble substance has black particles in it,
that are entirely or partially consumed when heat-
ed on platinum foil. (Coal.) Carbox. . - - 6

6. Evaporate a portion of the first solution or of F 2
to dryness, after adding hydrochloric acid, if not
already present, ignite the residue gently, moisten
it with concentrated hydrochloric acid, let stand a
short time, add considerable water, and digest the
mixture. A white poAvder, or perhaps a reddish
one if much iron is present, remains undissolved,
that feels gritty under the glass rod. Soluble
Silicic. - 1

7. The addition of dilute sulphuric acid to a small
quantity of the original substance causes efferves-
cence, that accompanies the evolution of a colorless
gas ; a drop of lime-water, suspended on the end
of a glass rod, and held above the liquid in the
test-tube, is made turbid. Carbonic. - - - - ^

6. In the same experiment a colorless gas is evolved,
havini^ an offensive odor, and blackening a piece of

132 SPECIAL METHODS OF ANALYSIS.

moistened lead-paper that is lield in the mouth of
the tube. {Uydrosulphurlc.) Sulpiiue. - - . 9
9. The first sohition, or F 2, after acidification with
hydrochloric acid, if not ah-eady acid, gives a white,
finely pulverulent precipitate with baric chloride.

SULPHUKIC. - -10

Sulphuric acid may be found also in the insoluble
substance in the course of the examination for
bases.

10. If a very small quantity of the solution of the sub-
stance is added to ammonic molybdate, a pale yel-
low precipitate is formed, at once, or after some time,
a part of which adheres strongly to the sides of
the tube ; the precipitate is soluble in ammonia.
Phosphoeic. 11

11. To a portion of the hot solution, containing a
slight excess of acid, add about twice its volume
of alcohol, and then dilute sulphuric acid or am-
monic sulphate, and filter if any precipitate is
formed, heat the filtrate until the alcohol is ex-
pelled, add ammonia in slight excess, and then
acetic acid until the ammonia is more than neutral-
ized, and finally calcic sulphate. A fine white pre-
cipitate appears, at once, or after some time.
Oxalic. 12

12. To a small portion of the dilute nitric acid solu-
tion of the substance, or of the aqueous solution
acidified with nitric acid, add argentic nitrate.

a. No precipitate is formed. (Traces of cyano-
gen or iodine may perhaps be found by applying

the tests in 12 5, and 13.) IT

h. A precipitate is formed.

Treat a small portion of the original substance
with a little dilute sulphuric acid, in a watch-glass,
and quickly invert another watch-glass, with a

DETECTION OF ACIDS. 133

drop of amnionic sulphide, saturated with sulphur,
in its centre, over the first one ; after a few min-
utes evaporate this drop of ammonic sulphide to
dryness with a gentle heat, and moisten the dry-
residue with ferric chloride. A deep red color
appears. Cyanogen-. 13

13. To a portion of the aqueous solution or extract of
the substance, add two or three drops of potassic
dichromatc, or enough to give a pale yellow color
to the liquid, and then a few drops of concentrat-
ed hydrochloric acid. A drop of this mixture on
starch-paper colors it blue. Iodine. - - - - 14

14. A portion of the first solution gives, w^ith ferric
chloride, a deep blue precipitate, unaffected by di-
lute acids, but decomposed by sodic hydrate with
the conversion of the blue color into a reddish
one. Ferkocyanogen. 15

15. a. 1^0 very decided reaction was obtahied in 12

for cyanogen. 16

h. A decided reaction was obtained for cyanogen.
To the dilute nitric acid extract of the substance,

or the aqueous extract acidified with nitric acid,
add argentic nitrate as long as a precipitate is
formed, filter, -wash the precipitate a little, dry it,
and ignite it gently in a porcelain crucible until it
is fused, pour a little water and a few drops of di-
lute sulphuric acid over the fused mass after it is
cool, put a piece of zinc in contact with it, and let
the whole stand some time ; finally filter, acidify
the filtrate with nitric acid, and add argentic ni-
trate.

a. No precipitate. - 17

1). A white precipitate is formed ; no iodine or
ferrocyanogen has been found. Chlorine. - - IT
c. A precipitate is formed, but it is not w^bite,

134 SPECIAL METHODS OF ANALYSIS.

or iodine or ferrocyanogen lias been found. - - 16

10. a. The precipitate in 12 was white, and no cyano-
gen, iodine, or ferrocyanogen, has been found.

Chlorine. 17

h. Not Avhite, or one or more of these substances
was found ; treaVthe precipitate obtained in 15, or,
if cyanogen was absent, that obtained in 12, with
amnionic hydrate, filter, and add dilute nitric acid
to the filtrate until acid reaction. A white pre-
cipitate appears, which, if abundant, collects in
curdy flakes on agitating the mixture. Chloeixe. 17

17. Treat a portion of the original substance with a
little dilute sulphuric acid if it is a solid, or with
concentrated acid if it is a solution, add copper
turnings, and heat the mixture. Red fumes are
evolved, which may be more readily perceived on
holding the tube over white paper, and looking
through it lengthwise. Nitric. - - - 18

18. a. A portion of the solid substance, when quickly
heated to a high temperature on platinum foil, is
blackened, with separation of carbon, and an odor

of burning organic matter is given off. - - 19

h. Not blackened. Absence of acetic, tartaric,
and other organic acids. Finis. - - - - B.

19. A portion of the solid or solution gives acetic
ether when heated with concentrated sulphuric
acid and alcohol ; the pleasant aromatic odor of
this ether may be most readily distinguished from
that of common ether, Avhich is formed at the
same time, after the liquid has become quite cold.
Acetic. - - 20

20. To a portion of the first solution, tliat must be tol-
erably concentrated, add ammonia until it is faint-
ly alkaline, filter if not clear, add a little amnionic

DETECTION OF ACIDS. 135

chloride, then calcic chloride, agitate tlie mixture

vigorously, and let it stand 10-20 minutes.

a. No precipitate is formed. - - - - 21

h. A white precipitate is formed ; filter, and mark
the filtrate F. 20. Digest the precipitate in the
cold, with sodic hydrate, with frequent agitation,
dilute, filter, and boil the filtrate. A white gelat-
inous precipitate is formed ; test it with ammonia
and argentic nitrate (§ 71). Taetaeic. - - 21

21. To F. 20, or to the clear mixture of original solu-
tion and calcic chloride obtained in 20, add consid-
erable alcohol.

a. No precipitate. Finis. - - - - B.
h. A white precipitate is fonnecl ; filter, wash the
precipitate with a little alcohol, dissolve it in a
small quantity of dilute hydrochloric acid, add am-
monia in slight excess, and boil the liquid some
time.

aa. No precipitate. 22

hh. A white precipitate is formed ; filter the liquid
while boiling hot, and mark the filtrate F. 21. Dis-
solve the precipitate on the filter in a very little
dilute hydrochloric acid, add ammonia in slight
excess, and boil this mixture. A similar white
precipitate is formed again. Citkic. - - - 22

22. F. 21, or the solution obtained in 21 that gave no
precipitate on boiling, may contain malic acid.
Add considerable alcohol to it.

a. No precipitate is formed. Finis. - - ^'
h. A white precipitate is formed. Probably Malic.
To be sure, treat the precipitate with acetic acid,
add alcohol, filter the liquid if not clear, add plum-
bic acetate to the filtrate, and ammonia until the
liquid is neutral, filter out the precipitate, wash it,

136 SPECIAL METHODS OF ANALYSIS.

suspend it in water through wliich a current of
sulphuretted hydrogen is passed, filter, evaporate
the filtrate to dryness on the water-bath, and heat
the residue, supposed to be malic acid ; maleic
acid should be formed (§ 73). - - - - B.

B.

DETECTION OF THE BASIC ELEMENTS.

1. a. The substance is a solution, or it is soluble in
water, or dilute or concentrated hydrochloric or
nitric acid. This solution will be referred to as

the^r^^ solution. 3

b. Not soluble, or only partially soluble ; separate
the soluble from the insoluble part by filtration ;
this filtrate will be referred to as the Jlrst solution. 2

2. This insoluble substance was found, in the exami-
nation for acids, to consist entirely of carbon. - 3
Not. Dry it, mix it intimately with four parts of

• potassic and sodic carbonate, and a little sodic ni-
trate, fuse the mixture 10-20 minutes on platinum
foil, and exhaust the fused mass with hot water ;
decant off this aqueous extract, wash the residue
once or twice by decantation, then treat it with
very dilate hydrochloric acid, and evaporate the
mixture to dryness ; moisten this second residue
with concentrated hydrochloric acid, and, after a
while, add water, heat, and finally separate this
acid solution from the insoluble silica, by filtra-
tion.

Acidify the aqueous extract of the fused mass, ob-
tained above, with hydrochloric acid, and test a
small portion of it for sulphuric acid with baric
chloride ; if a fine white precipitate is formed, and
lead or barium is subsequently found among the

DETECTION OF THE BASIC ELEMENTS. 137

basic elements, the insoluble substance was com-
posed, at least in part, of plumbic or baric sul-
phate ; if lead or barium is not found, but calcium
is, then the insoluble substance consisted, at least
partly, of calcic sulphate, which requires considera-
ble water or dilute acid for its complete solution ;
if no sulphuric acid is found, the insoluble sub-
stance contained only silica or silicates, besides,
possibly, a fluoride and carbon.

Mix the acid solution, filtered from the silica as
above, and the remainder of the aqueous extract
together, and without filtering out any precipitate
that may be formed, proceed with the analysis as
in 3, if it is desired to analyze this solution sepa-
rately, in order to ascertain the composition of the
insoluble part of the substance ; but it will not be
found, in any case, to contain arsenic or ammoni-
. um, nor will copper or zinc be likely to be found
in it, and not in any case unless it contained silica •
lead and barium may be present as sulphates, and
the latter possibly as a silicate.
Potassium and sodium cannot, of course, be tested
for in this solution ; if it is desired to examine the
insoluble substance with respect to the presence of
these metals, the silicate must be attacked with
hydrofluoric acid or a fluoride, in the manner di-
rected for the quantitative analysis of silicates.
(§ 58, c.)

If it is not necessary to analyze this solution sepa-
rately, it may be mixed at once with the Jirst solu-
tion^ reserving, however, a portion of this latter
for the examination for the alkaline metals. - - 3
3. Heat a portion of the nearly neutral, first solution
to boiling, add to it about its volume of alcohol,
or twice its volume if the solution is very dilute,

188 SPECIAL METHODS OF ANALYSIS.

and then add dilute sulphuric acid as long as a pre-
cij^itate is formed.

a. No j)recipitate is formed, even after vigorous
agitation and some time ; expel the alcohol from
the liquid by boiling it a few minutes, and mark it

F. 3.

h. A white precipitate is formed ; let the mixture
stand awhile, filter the liquid while hot, boil the
filtrate a few minutes to expel the alcohol, and
mark it F. 3. - - ....

4. Agitate the precipitate obtained in 3 vigorously
with considerable water, filter, and add amnionic
oxalate to the clear filtrate. A white precipitate
indicates Calcium. . . _ . -

5. Treat the contents of the filter in 4 with ammonic
tartrate, heat gently, filter, acidify the titrate
with acetic acid, and add a little potassic dichro-
mate. A yellow precipitate indicates Lead.

6. Wash the residue on the filter in 5 well, boil it
about 10 minutes with 8-10 times its bulk of sodic
carbonate, add water, filter, wash the contents of
the filter very carefully, pour a little dilute hydro-
chloric acid over this residue, and add calcic sul-
phate to the solution that passes through. A fine
white precipitate, or a turbidity, indicates Barium.

7. Put about a third of F. 3, or a corresponding
amount of the first solution, into a small flask, add
baric hydrate as long as it gives a precipitate, and
then a little more, so as to be sure of an excess,
heat the mixture, and hold a piece of nioistened
red litmus-paper or yellow turmeric-pnper in the
tube. The paper is colored blue or brown. Am-
monium.

8. Heat the mixture in 7 until all or nearly all the
ammonia is expelled, filter, add a little baric hy-

DETECTION OF THE BASIC ELEMENTS. 139

drate to the filtrate, to bo sure that no further pre-
cipitation will be produced, then add ammonic
carbonate as long as a precipitate is formed, avoid-
ing, however, a great excess of the reagent, heat
and filter, and evaporate the filtrate nearly to
dryness.

A drop of this filtrate, evaporated to dryness in
the platinum wire loop, gives a yellow color to the
flame of a Bunsen's gas-burner. Sodium. - - - 9

9. "in a similar experiment the flame is violet, or vio-
let-red when seen through blue glass. Potassium. 10

10. To a small portion of F. 3, add ammonia very
carefully until the free acid is just neutralized, and
then a little ammonic sulphide, drop by drop, with
constant agitation, and heat the mixture.

a. No precipitate is formed at any time. (Traces v
of copper, arsenic, iron, and manganese, may per-
haps be found by applying the tests described in
10 b, 12, 14, and 15 ^»). 18

h. A precipitate is formed.

To a small portion of F. 3, add ammonia until the
well-mixed liquid smells strongly of the reagent,
and let the precipitate settle if any is formed. The
clear supernatant liquid is blue. Copper. - - 11

11. In the same experiment a red flocculent precipi-
tate is obtained, the color of which may, however,
not appear, in case much copper is present, until it
has been collected on a filter and washed a few
times. Ieon. 1^

12. If copper has been found in notable quantity, put
the remainder of F. 3 in a small flask, add two
or three pieces of pure zinc, and close the flask
with a perforated cork, in which is a glass tube
drawn out to a fine jet.

140 SPECIAL METHODS OF ANALYSIS.

If copper was not found, take only a small part of
F. 3 for this trial.

Care must be taken not to inhale the gas from the
flask, if there is any reason to suspect that arsenic
is present.

After the hydrogen has been evolved a few min-
utes, wrap a towel around the flask, ignite the jet
of gas, and hold a cold porcelain surface in the
flame. Black lustrous spots are deposited on the
porcelain surface where the flame comes in contact
with it. Aksenic. 13

13. a. Copper was not found, and only a small portion

of F. 3 was taken for the test in 12. - - - 14
h. Copper was found, and a, large portion of F. 3
is under examination. Allow the action of the
zinc to continue 10-15 minutes, or until all the cop-
per is precipitated ; a much longer time may be re-
quired if the solution contains a notable quantity
of nitric acid ; finally filter the liquid from the pre-
cipitated metal, and mark the filtrate F. 13. - - 14

14. Add a little nitric acid to a portion of F. 13, or of
F. 3, if there is no F. 13 and the first solution did
not already contain free nitric acid in excess, and
heat the mixture to boiling.

a. An unmistakable reaction for iron was obtained

in 11. 15

h. Not. To a small portion of this solution add
potassic sulphocyanate. A deep red color appears.
Iron. -..-_-•.- 15

15. To a large portion of the solution obtained in 14,
add amnionic carbonate in excess.

a. The precipitate which may have been formed
at first is entirely re-dissolted by the excess of the
reagent, and the solution remains quite clear, even
after a hot digestion of 12 hours. - - - 17

DETECTION OF THE BASIC ELEMENTS. 141

h. Not. Filter the precipitate out, wash it with
hot w^ater, dry a large portion of it, and mix it in-
timately with three or four times its bulk of a mix-
ture of equal parts of potassic and sodic carbon-
ate, and of potassic or sodic nitrate, and fuse the
mixture well on platinum foil. The fused mass is
bluish green. Manganese.

If the substance contains little or no copper or
iron, this reaction for manganese may sometimes
be obtained with the original substance, when not
obtained here (§53). 16

10. Boil the fused mass on the platinum foil with two
or three cubic centimetres of water, until it is loos-
ened from the foil, filter, add dilute nitric acid to
the filtrate, drop by drop, as long as any efferves-
cence is produced, and then add ammonia very
slowly and carefully, until, after stirring well, the
liquid has a faint alkaline reaction ; heat the mix-
ture a few minutes, and let it stand a long time in
a warm place, if no j^recipitate appears at first. A
white flocculent precipitate is formed, at once, or
after some time. Aluminium. - - - 17

17. To another portion of the first solution add sodic
hydrate in excess, boil, and filter ; to the filtrate
add a few drops of ammonic carbonate, and then
ammonic chloride in excess, boil the mixture as
long as any odor of ammonia is given off, and a
portion of the filtered liquid gives no further pre-
cipitate on being boiled still more ; filter the
whole, and add potassic ferrocyanide to the filtrate.

A white precipitate or a turbidity appears. Zinc. 18

18. a. The substance contains no phosphoric acid, or

only traces of it. 19

b. It does contain a notable quantity of this acid.
Add ferric chloride to another portion of F. 13, or

142 SPECIAL METHODS OF ANALYSIS.

to a corresponding quantity of F. 3, if there is no
F. 13, until a drop of the mixture gives a reddish
precipitate with ammonia. - - - - 19

19. To the solution to which Fe^Cl^ has been added
(18), or to the remainder of the filtrate F. 13, if
no P2O5 was present in the substance, or to a cor-
responding quantity of F. 3, if there is no F. 13,
add ammonic carbonate until a slight permanent
precipitate remains after vigorous stirring ; if no
precipitate appears, the reagent may be added un-
til it is in slight excess, and the solution is faintly
alkaline.

a. No ferric salt has been added to the solution,
and it remains quite clear, or only a fine white pre-
cipitate is formed after boiling it. - - - 20
h. AJlocculent precipitate is formed ; heat the so-
lution to boiling, add a boiling solution of sodic
acetate as long as a precipitate is formed, and fil-
ter the hot liquid immediately ; mark this filtrate
F. 19. - 2a

20. a. Calcium has been found. - - - - 21
h. Not. To test for traces of the metal, add am-
monic sulphide to the filtrate from the precipitate
by sodic acetate, or, if this precipitation was not
found to be necessary in 19, to the liquid contain-
ing ammonic carbonate in slight excess, after acidi-
fication with acetic acid if not clear, filter out any
precipitate that may be formed, and add ammonic
chloride and oxalate to the filtrate ; a fine white
precipitate, insoluble in acetic acid, indicates Cal-
cium (traces). 21

21. Add ammonic chloride and carbonate to F. 19, or
to the liquid already containing ammonic carbon-
ate in sliglit excess, and which gave no flocculent
precipitate with the reagent, boil the mixture, fil-

DETECTION OF THE BASIC ELEMENTS. 143

ter, add ammonia in excess to the clear and cooled
filtrate, filter again if this reagent produces any-
precipitate, add hydric disodic phosphate to the
filtrate, agitate the mixture vigorously, and set it
aside for several hours if no precipitate appears at
first. A white crystalline precipitate appears,
that, if formed slowly, adheres to the sides of the
tube ; with the magnifying glass, and usually with
the unassisted eye, the crystals are seen to be slen-
der prisms. Magnesium.
Finis,

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§ 89. OCCURKENCE OF SUBSTANCES. 145

C.

For the mode of occurrence of the substances for whose
detection directions are given in the preceding pages, in
agricultural materials and products, consult Table X, ex-
cept in case of the following, which are not widely dis-
tributed, or whose occurrence presents comparatively less
interest, because they have not been quantitatively esti-
mated in these materials or products.

Acid, acetic, besides occurring in vinegar, which re-
sults from the action of the air on alcoholic liquors, is
found among the products of the putrefaction, or of the
destructive distillation of organic matter.

Acid, citric, is found in lemons, and in most other acid
fruits^ such as gooseberries, cherries, etc.

Acid, lactic, is the acid of sour milk, and is found also
in some animal juices, and sometimes in urine.

Acid, malic, is found in unripe apples, and in most un-
ripe fruits, together with citric acid, and also in potatoes,
in many roots, and in the stems and leaves of many
plants, such as rhubarb, tobacco, etc.

Acid, tartaric, is found, like malic acid, in many fruits,
and particularly in the grape ; it occurs also in the roots,
stems, and leaves, of many plants.

Arsenic may be found occasionally in superphosphates,
where it was derived from the sulphuric acid used in the
manufacture of the article ; it is also a frequent and dan-
gerous ingredient of bright green pigments.

Barium may sometimes be found as a silicate in some
common rocks, and hence in soils.

Copper may sometimes be found in culinary products
where vessels made of the metal or its alloys have been
used ; it is a frequent and harmful ingredient of bright
green pickles

7

146 § 89. SPECIAL METHODS OF ANALYSIS.

Cyanogen is sometimes to be found among the products
of the decomposition of nitrogenous organic matter in
the presence of strong bases, particularly if the decom-
position has been aided by heat.

Ferrocyanogcn is a product of the decomposition of
nitrogenous animal matters by heat, in the j)resence of a
strong base and iron.

Iodine is very widely but sparingly diifused.

Lead may sometimes be found in water that has been
in contact with it, and in superphosphates ; in this latter-
case it is derived from the sulphuric acid used in the
manufacture of the fertilizer; it is also a common ingfre-
dient of pigments.

Manganese occurs in nearly all soils, and is generally
found, at least in traces, in plants, and whatever is pro-
duced from them.

Zinc may occur in soils in the neighborhood of beds of
zinc ore, and in the ashes of j)lants grown on such soils.

II.

SPECIAL METHODS OF QUANTITATIVE SEPARATION OF
SUBSTANCES.

Under this head a few special methods of quantitative
separation of substances, that often occur in agricultural
chemical analysis, are described with full details and di-
rections, and in a manner convenient for reference. In
this way much repetition is avoided in the chapters treat-
ing of special analyses.

By consulting Table X, at the close of the book, the
analyst may ascertain how much he will probably find of
each of the constituents of the compound he is about to
analyze, and, knowing the strength of his reagents, he
can form some idea as to the quantities of these to be used
to pro'duce complete precipitation.

§ 90. DESICCATION. 147

DESICCATION.

90. One of the more frequent determinations in agri-
cultural analysis is that of water, ash, and organic matter.

In the elimination of water, or the desiccation of the
substance or solution, the object may be to determine the
hygroscopic water of the substance, or it may be the
estimation of the total amount of solid matter in a solu-
tion.

a. For the estimation of hygroscopic moisture, dry the
substance well in the air, so that it shall be thoroughly
air-dried, or under a bell-jar over sulphuric acid, as may
be directed in each special case ; then heat a weighed
quantity of it in a watch-glass in the steam or air-bath to
the temperature indicated in each case, as long as it loses
weight ; while weighing the substance, it should be en-
closed between two watch-glasses that fit well together
by their ground edges.

b. Sometimes, as in the case of gypsum containing no
volatile matters but water, the substance can be ignited
at once ia a covered crucible. A gentle heat should be
applied at first, and the temperature should be gradually
raised, at least almost to a red heat in some cases.

c. When the substance contains a large amount of wa-
ter, as in the case of the green parts of plants, it is best
to dry a large, weighed quantity in a drying-chamber, at
from 60° to 80° C, determine the loss of weight at this
temperature, and then proceed as in a, with from 3 to 6
grms. of this partly dried substance.

d. Sometimes the substance to be dried contains other
volatile ingredients, as ammonia for example ; in this
case the desiccation must be performed in a current of
dry air, or an inactive gas, like hydrogen, by means of
which the volatile products are carried into some absorb-
ing solution. Procure a deep water-batn, through which
a tube of the same material passes laterally, and projects

148 § 90. SPECIx\L METHODS OF ANALYSIS.

a little beyond the sides ; weigh the substance out in a small
porcelain or platinum boat, and insert the boat in a glass
tube open at both ends, and drawn out and bent down at
one end ; put this glass tube in the copper tube of the wa-
ter-bath, immerse the end of the glass tube, that is bent
downwards, in a measured quantity of standard sulphuric
acid, and connect the other end with an apparatus from
Avhich dry hydrogen is evolved. Apply heat to the water-
bath, and when the desiccation is completed, remove the
boat, rinse the glass tube into the flask containing the
acid, boil the acid a little to expel carbonic acid, that
misrht have been carried over with the ammonia, and
titrate with soda solution in the usual manner (§ 45, c).

e. For the estimation of the amount of solid substances
in a solution^ evaporate a measured or weighed quantity
on the water-bath, and dry the residue at the temperature
indicated in each particular case ; this temperature may
range all the way from 100° to 180° C.

f. If the liquid contains other volatile matters besides
water, as in the case of urine, which may give off am-
monia when heated, put it in a porcelain or a platinum
boat, which has been previously about two-thirds filled
with coarsely pounded and well-washed glass or coarse
quartz sand, dried at 100°, and weighed, and carry on the
evaporation as in the case of a solid evolving ammonia
when heated (d).

g. If the solution contains substances that are decom-
posed at a temperature above 100°, and yet it is difficult
to dry the residue left on evaporation of the liquid thor-
oughly at that temperature, imbed the dish containing
the residue in sand that is heated to 100° C, put the
whole over a dish of concentrated sulphuric acid under
the receiver of the air-pump, and exhaust the air ; after
the sand has cooled, repeat the process with a fresh quan-
tity of heated sand, and so on as long as there is any loss
of weiorht.

§ 91. INCINERATION. 149

h. If the substance in solution is liable to form hard
clumps on drying that retain water mechanically enclosed,
and yet the residue cannot be heated much above 100 C,
mix it with ^ |, or ' |g of its weight of rather finely pulver-
ized crystallized gypsum, or of pure ignited baric sul-
phate, that has been artificially prepared, or with 3 or 4
times its weight of well-washed fine sand. If gypsum is
used, it should be tested beforehand, to see whether it
loses any weight at 100°. The mixture should be well
stirred as the evaporation approaches dryness. Heat the
residue at 100° in the usual manner as long as it loses
weight.

INCINERATION, OR ESTIMATION OF ORGANIC MATTER.

91. The dried residues obtained in the preceding sec-
tion are often examined for organic matter by ignition
until this matter is burned away, or incineration.

a. The ignition is performed in a platinum dish or cru-
cible at as low a temperature as possible, with provision
for the access of air to the substance along the surface of
the lid of the crucible, as directed for the incineration of
filters (§ 40) ; or a piece of platinum foil may be bent so
as to rest on the bottom of the dish and on the rim, and
extend some distance beyond the latter.

h. A portion of the original solid substance may be in-
cinerated at once in the muffle furnace, as described in
§ 123, c, under preparation of the ash of plants for analy-
sis. Then, on subtracting from the loss of weight iu this
trial the amount of water in the quantity of substance
taken, as may be calculated from the results of the esti-
mation of hygroscopic water in another portion of the
substance, the remainder will be the organic matter, or
other volatile matter besides water.

c. A part of the . carbon sometimes obstinately resists

150 § 91. SPECIAL METHODS OF ANALYSIS.

combustion ; to eliminate this, one of two courses may-
be followed.

1. Exhaust the mixture of ash and coal with hot water,
collect the insoluble part on the filter, wash, dry, and ig-
nite it ; the coal will generally be found to burn much
more readily after this treatment, and the ash can more-
over be heated to a higher temperature than before with-
out fear of loss. Add the ash so obtained to the aqueous
extract and washings, evaporate to dryness, ignite gently,
and weigh.

2. Or, weigh the mixture of ash and unconsumed car-
bon, determine carbonic acid (d) in the whole or a j)or-
tion of it, collect what is insoluble in the nitric acid in the
determination of the carbonic acid, on a dried and weigh-
ed filter, wash it well, dry at 110° C, weigh, ignite until
the carbon is completely burned, and weigh again. The
loss of weight gives the unburned carbon in that portion
of the original ash taken ; calculate the amount of coal
for the whole quantity of the original mixture of ash,
including carbonic acid and coal, and deduct it from the
same.

d. A portion of the carbon in the organic part of the
substance ignited may remain behind in combination with
the metallic oxides as carbonic acid ; sinca this does not
properly belong to the ash or inorganic part of the sub-
stance, it should be determined and deducted from the
total weight of the ash.

For this purpose estimate the carbonic acid (§ 60) in a
i:)ortion of the ash, or the whole of it, according to the
quantity in hand, calculate the amount for the whole
quantity of the ash, if only a portion was used for the
analysis, and deduct it from the same.

A substance may, however, contain a notable quantity
of carbonic acid before ignition, as, for example, a soil
with carbonate of lime in it. In this case the ignited
residue should bo moistened with ammonic carbonate,

§ 91. QUANTITATIVE METHODS. 151

carefully dried, gently ignited, and weighed, and the
operation must be repeated as long as there is any gain in
weight, in order to be sure that there is at least as much
carbonic acid in the substance after ignition as before.
Then determine carbonic acid in the ash, or a portion of
it, and in a portion of the original substance ; the excess
in the ash over what was in the quantity of substance
taken is to be subtracted from the weight of the ash.

e. Small quantities of organic matter, as in water, may
be determined by the following volumetric j^rocess (Kuhel^
Fresenius^s Zeitschrift^ 6, 252).

Dissolve about 0.4 grm. of crystallized potassic per-
manganate in 1 litre of water, and also 0.398 grm. of pure
oxalic acid in 1 litre of water.

Put 100 c.c. of distilled water and 10 c.c. of a dilute
sulphuric acid, containing 30 grms. of concentrated acid
in 100 c.c, in a flask of about 300 c.c. capacity, heat the
mixture to boiling, add 3-4 c.c. of the permanganate so-
lution, boil the red liquid 5 minutes, remove the lamp, and
add 10 c.c. of the solution of oxalic acid ; potassic per-
manganate is then cautiously added from a burette or pi-
pette, with constant stirring, until a faint red color ap-
pears throughout the liquid. The total amount of
permanganate added, corresponding to the 10 c.c. of the
oxalic acid solution, = 2 milligrammes.

Now, to make a determination of organic matter in a
sample of drinking water, for instance, boil 100 c.c. of the
water in a flask of 400 or 500 c.c. capacity, down to ''\^ its
initial volume, to decompose ammoniacal compounds that
are very liable to be present in such a water, by means of
the calcic carbonate that is also nearly always present ;
add distilled water until the original volume is nearly re-
stored, and 10 c.c. of the dilute sulphuric acid ; heat to
boiling, add 5 or 6 c.c. of the permanganate solution, and
boil 5 minutes, whereby the red color should not be de-
stroyed ; then add 10 c.c. of the oxaHc acid, and restore

152 § 92. SPECIAL METHODS OF ANALYSIS.

the red color by adding the permanganate solution from
the burette as before. The permanganate added this time
is consumed in oxidizing, not only the 10 c.c. of oxalic
acid that was added to the solution, but also other organic
matter, and therefore more permanganate will be required
than when the oxalic acid was mixed with distilled water,
as in the first experiment. Multiply the number of milli-
grammes of permanganate in this additional quantity of
the solution used, by 5, for the organic matter, expressed
in milligrammes. The determination is only an approxi-
mate one, since different kinds of organic matter require
difi'erent amounts of oxygen for their complete oxidation,
while in the above estimation it is assumed that the same
amount is consumed by the same quantity of organic mat-
ter of whatever kind.

92. Estimation of Sulphur {and Chlorine) in Organic
Compounds.

Fuse 2 parts of a mixture of pure caustic potassa
free from sulphuric acid (or chlorine) with '|g part of pure
potassic nitrate in a silver dish, with the addition of a
little water. When the mixture is cold, add 1 part (3 to
4 grms.) of the finely pulverized substance, fuse the
whole with constant stirring with a silver spatula, and
continue the application of the heat until the mass has
become quite white ; if it does not readily become so, a
little more potassic nitrate may be added.

Dissolve the fused substance in dilute nitric acid, evap-
orate to dryness, and eliminate silica (§ 58, a, 1), and in
the filtrate from this, precipitate the sulphuric acid, into
which the sulphur in the original substance has been con-
verted by oxidation, with baric chloride (§ 59), or with
baric acetate, if chlorine is to be determined in the filtrate
from the baric sulphate ; the chlorine in this filtrate is
precipitated by argentic nitrate (§ 63, a).

93. Separation and determination of Potassium^ Sodi-

§ 93. QUANTITATIVE METHODS. 153

wm, Calcium^ Magnesium^ Alitminium, Iron, and Man-
ganese, and Phosphoric and Sulphur ic acids.

This is one of the most frequently recurring separations
in agricultural chemical analysis.

For the best general method of separation in each par-
ticular case, the analyst will be referred tg one of the ta-
bles at the end of this section, in which the whole course
to be followed will be marked out in a few words, while
more detailed descriptions will be given in the following
paragraphs of some of the necessary manipulations men-
tioned in the table.

A. Precipitation of almnina, X\fi^, ferric oxide, Yefi^,
Sindi phosphoric acid (anhydride), PjO^., and estimation of
the two bases.

If the substance contains a notable proportion of or-
ganic matter, this should first be destroyed in the solu-
tion, and the iron completely oxidized to ferric oxide at
the same time, by treatment with an active oxidizing
agent.

This oxidation may be effected by passing chlorine gas
through the solution until it is nearly saturated ; if this
course is followed, the solution should be heated after-
wards, until the excess of chlorine is entirely expelled.

Or, instead of using chlorine, the solution may be evai>
orated nearly to dryness, and sodic or potassic hydrate
added in slight excess, and sodic carbonate and a little so-
dic or potassic nitrate ; then dry the mixture completely
in a platinum dish, and ignite the residue gently until the
organic matter is destroyed ; exhaust the mass with water,
treat it with dilute hydrochloric acid, add this solu-
tion and the washings to the aqueous one, and proceed as
directed below for the estimation of ferric oxide, etc. If
a residue remains that is insoluble in hydrochloric acid,
dry, ignite, and w^eigh it, and add the amount to the
silicic acid already obtained.
7"*

154 § 93. SPECIAL METHODS OF ANALYSIS. •

1. Case in which there is enough ahimi?ia and ferric
oxide present to combine with all the phosphoric acid.
The filtrate from the precipitate by sodic acetate, obtained
in a qualitative test in the manner described below, gives
no reaction for phosphoric acid with aramonic molybdate.

To the not too concentrated solution add sodic carbon-
ate with constant stirring, until a few scattered flakes of a
precipitate remain permanent, heat to boiling, remove the
lamp, and add immediately an excess of a boiling hot so-
lution of sodic or ammonic acetate ; this reagent precipi-
tates all the AI2O3, Fe203, and P^O^ ; filter rapidly while
hot, and wash the contents of the filter with boiling water,
containing a little ammonic acetate ; dissolve the precipi-
tate, without drying it, in hot, dilute hydrochloric acid,
wash the filter out well, mix the solution and washings by
vigorous stirring, add water, if it is necessary, to bring
the liquid to such a volume that it can be conveniently
divided in two equal parts, and mix carefully again by
stirring, divide it accurately, precipitate one part with
ammonia in slight excess, as directed for the precipitation
of alumina (§ 51), filter, wash with hot water, dry, ignite
precipitate and filter separately, and weigh ; the result,
multiplied by two, gives the total amount of Al^Og, Fe203,
and P2O5 in the undivided solution.

Keduce the ferric to ferrous oxide in the other half of
the solution, and estimate the iron with potassic perman-
ganate (§ 52, h) • or, as a sulphuric-acid solution is better
adapted for that process, this half of the solution may be
precipitated with ammonia also, and the precipitate wash-
ed, and dissolved, without drying it, in dilute sulphuric
acid. The amount of ferric oxide being estimated from
the result, multiply by two and thus get the quantity of
Fe^Og in the undivided solution.

The difference between the total weight of Al^Og,
Fe^Og, and P^O,^, and the sum of the Fe^Og, as determined
above, and the P^O^ to be determined in another portion

§ 93. QUAXTITATIVE METHODS. 155

of the solution and estimated for the amount of solution
taken for this analysis, will give the Al^Og.

2. In case there is not Fe^Og and Al^Og enough present
to combine with all the phosphoric acid, more iron must
be added, until a drop of the liquid, on a watch-glass,
gives a reddish precipitate with a little ammonia, and the
amount of iron so added is to be subtracted from the total
amount found subsequently. This addition of iron is
most conveniently made in tlie form of a carefully meas-
ured quantity of an accurately titrated solution of ferric
chloride (Fe^ClJ, about '1^ the strength of the reagent or-
dinarily used. Proceed then as in 1.

B. The method of removing phosphoric acid by means
of metallic tin admits of the determination, in a conven-
ient manner, of this acid, and alumina, ferric oxide, man-
ganous oxide, lime, and magnesia, in the same portion of
the solution.

On evaporating to dryness to remove silica, after moist-
ening the dried residue with concentrated hydrochloric
acid in the usual manner, add nitric acid, dilute with
water, filter, wash the insoluble silica on the filter, evap-
orate the filtrate and washings nearly to dryness, or until
all the hydrochloric acid is expelled, dissolve the residue
in concentrated nitric acid, heat the solution to boiling in
a beaker covered with a large watch-glass or an inverted
funnel, and add pure tin in small grains, and in small
portions at a time, to an amount about six times as great
as that of the phosphoric acid supposed to be present, di-
gest the mixture 5 or C hours in a warm place, dilute and
decant the clear supernatant liquid on the filter, and wash
the precipitate, containing stannic oxide, stannic phos-
phate, and perhaps some alumina and ferric oxide, several
times by decantation with boiling dilute nitric acid, and
finally with a little water ; then digest it with amnion io
sulphide, wash the undissolved aluminic hydrate and fer-
rous sulphide first with hot ammonic sulphide, and then

156 § 93. SPECIAL METHODS OF ANALYSIS.

with water to the successive portions of which less and
less amnionic sulphide is added ; dissolve it in dilute hy-
drochloric acid, and add the solution to the first filtrate
from the stannic oxide, etc., containing the main part of
the alumina and ferric oxide.

The solution obtained by treating the precipitated
stannic oxide and phosphate, etc., by ammonic sulphide,
contains all the j^hosphoric acid {Baehei\ Zeitschnft filr
die gesammten Naturwissenschaften^ 1864, 293. Fresenius's
Zeitschrift^ 4, 122) / if its volume has been increased to a
considerable bulk by the washings of the precipitate of
aluminic hydrate and ferrous sulphide, concentrate it by
evaporation, filter again if not clear, and precipitate the
phosphoric acid with magnesia mixture in the usual man-
ner (§ 61, a).

In the filtrate from the precipitated stannic oxide and
j)hosphate, etc., determine the bases, as directed in A, C,
and D, except that, since the precipitate by sodic acetate
in A contains no phosphoric acid, the difference between
the total weight of the precipitate by ammonia, and the
weight of the ferric oxide, as determined by potassic per-
manganate, gives the alumina.

The method is not applicable in the presence of hydro-
chloric acid or chlorides.

C. Precipitation of manganic hinoxide^ MnO„, in the
filtrate from, the precipitate by sodic acetate in A.

Heat this filtrate, which should he free from ammonic
salts, and tolerably concentrated, to 50 or 60° C, and con-
duct chlorine gas through it until it is saturated, or as long
as any precipitate is formed ; filter out the precipitate, add
more sodic acetate to the filtrate, pass chlorine through
again, and add this second precipitate to the first, if any
is obtained. Wash the precipitated manganic hydrate
first by decantation and then on the filter, dry this, sepa-
rate the precipitate from it as completely as possible, burn
it and dissolve the ash and the precipitate in concentrated

§ 93. QUANTITATIVE METHODS. 157

hydrochloric acid, remove any great excess of acid by
evaporation, and precipitate the solution with sodic car-
bonate. (§ 53.)

Heat the filtrate from the precipitate by chlorine as long
as any odor of the gas is perceived.

D. Precipitation of llme^ CaO^ and magnesia, MgO^
in the filtrate from the precipitate by sodic acetate (A) or
by chlorine (C). Neutralize the solution with ammonia if
it is acid, and proceed as directed in § 50 6 to precipitate
lime with ammonic oxalate, and magnesia with hydric
disodic phosphate.

M Separation and determination of sulphuric acid
{anhydride), SO^. Precipitate the acid with baric chlo-
ride in the slightest possible excess, and preserve the
washings with water alone, while those with cupric acetate
may be thrown away. (§ 59.)

i^ Estimation of phosphoric acid (anhydride), P^O^,
in the filtrate from the precipitate by baric chloride.

Add ammonia in slight excess only, if much iron or
aluminum is present, otherwise a mixture of ammonia and
ammonic carbonate, as long as a precipitate is formed,
digest the mixture a considerable time until the free am-
monia is expelled, wash the precipitate well, dissolve it,
without drying it, in nitric acid, and eliminate PjO^ with
ammonic molybdate. (§ 61. b.)

G. Elimination of the cdkaline metals as chlorides.

(1.) Precipitate SO3 by the slightest possible excess of
baric chloride, if this has not already been done ; evapo-
rate the mixture on the water-bath until most of the free
acid has been removed, add pure milh of lime in slight
excess, digest some time on the water-bath, and filter out
the precipitated Fe.Og Aip^ MgO, and, SO3 and P,0,.
"Wash the precipitate as long as the washings make argentic
nitrate turbid, precipitate the excess of lime in the concen-
trated filtrate and washings, by ammonic carbonate con-

158 § 93. SPECIAL METHODS OF ANALYSIS.

taining excess of ammonia, let the precipitate settle, filter,
evaporate to dryness, and ignite ; dissolve the residue in
water, and precipitate again with ammonia and ammonic
carbonate, filter, evaporate to dryness, and ignite; and re-
peat tliis operation as long as these reagents cause any
turbidity; finally, ignite gently, weigh the alkaline chlo-
rides thus obtained, and determine potassium and sodium
in the mixture by the indirect process (§ 46 d)^ or, if greater
accuracy is desired, precipitate potassium with platinic
chloride (§ 46 h),

(2.) Precipitate the SOg in the boiling solution with
baric chloride in slightest possible excess, if this has not
already been done, evaporate the mixture on the water-
bath until most of the free acid is removed, add some wa-
ter and then ammonia and ammonic carbonate as long as
a precipitate is formed, and finally a little ammonic oxa-
late, digest on the water-bath, filter, and wash the contents
of the filter carefully. Evaporate the filtrate and wash-
ings to dryness (§ 37), ignite the residue to expel ammo-
niacal salts, weigh roughly, and add a quantity of a con-
centrated solution of pure oxalic acidxhixt contains enough
of the acid to make quadroxalate with an amount of po-
tassa equivalent to all the bases present, evaporate to dry-
ness, and ignite again. By this process, magnesia and
traces of lime, baryta, ferric oxide, etc., that may possibly
be present, are rendered insoluble in water. Treat the ig-
nited residue with a small quantity of boiling water, throw
it on a filter, wash it with several small portions of boiling
water, as long as anything is dissolved, add hydrochloric
acid in slight excess to the filtrate and washings, evaporate
to dryness, and ignite the residue of alkaline chlorides
gently, weigh, and determine potassium and sodium by
the indirect process (§ 46 d), or with platinic chloride
(§ 46 h).

If, when these chlorides are dissolved in water, a clear
solution is not obtained, or if the solution has a basic re-

§ 93, QUANTITATIVE METHODS. 159

action, it should be evaporated to dryness and the residue
treated with oxalic acid again.

(3.) According to Stohmann {Fresenius's Zeitschrift, 5,
306), potassium may be separated out at once by platinic
chloride from a solution containing only alkalies and alka-
line earths.

Having precipitated the sulphuric acid completely as
above in the boiling solution of about 10 grms. of the
substance, filter out the precipitate if the quantity of it is
large ; if but small, let it remain in the liquid ; dilute the
liquid, when cool, to 1000 c.c. and mix the whole thor-
oughly together. To 100 c.c. of the clear solution add an
amount of platinic chloride containing about 2 grms. of
the metal, evaporate the mixture nearly to dryness, and
proceed as directed for the separation of potassium and
sodium by platinic chloride (§ 46 h). The method is based
upon the fact that the double chlorides of calcium, barium,
and magnesium, and platinum, are soluble in water and
alcohol, as well as the double chloride of sodium and
platin um.

H. Reparation oi phosphor'iG acid alone.

(1.) Evaporate the hydrochloric acid solution, contain-
ing no great excess of iron over the phosphoric acid, to
dryness on the water-bath, to eliminate silica, moisten the
perfectly dried residue with about 2 c.c. of concentrated
hydrochloric acid, and, after a while, add about 10 c.c. of
concentrated nitric acid (Sp. Gr. = 1.2) for every 0.15
grm. of phosphoric acid supposed to be present, dilute
with water, filter if necessary, and wash the residue of in-
soluble silica ; evaporate the filtrate and washings nearly
to dryness, dissolve the residue in about half as much
concentrated nitric acid as was added before, and proceed
to precipitate phosphoric acid with amnionic molybdate
(§ 61 h). [Fresenius's Zeitschrift, 4, 404.)

(2.) To the solution of the phosphate add ferric chloride
in slight excess over the phosphoric acid, if there is not

160 § 93. SPECIAL METHODS OF ANALYSIS.

already enough alumina and ferric oxide present, so that,
when the solution is nearly neutralized with sodic hydrate,
heated to boiling aud precipitated with sodic acetate in
excess, the filtrate gives no reaction for phosphoric acid.

Nearly neutralize the solution with sodic hydrate or
carbonate, heat to boiling, and add sodic acetate in excess,
filter the mixture while hot, wash with boiling water con-
taining a little ammonic acetate, dissolve, without igniting,
in dilute hydrochloric acid, wash the filter out carefully,
dilute the solution moderately, add rather a large-quantity
of citric acid, and then an excess of ammonia ; if enough
citric acid is present, the solution remains clear. Finally,
add magnesia mixture to the solution, and precipitate
phosphoric acid in the usual manner. (§ 61 a.)

The solution should not contain too large an excess cf
hydrochloric acid, and a great excess of citric acid must bo
avoided also. The method gives the best results when the
proportion of phosphoric acid is large, as compared with
the alumina and ferric oxide ; if these oxides are present
in large quantity, it may be necessary to re-dissolve the
precipitate by magnesia mixture in hydrochloric acid, add
citric acid, and re-precipitate the phosphoric acid by am-
monia and a little magnesia mixture.

(3.) In solutions containing a great excess of ferric oxide,
it is better to reduce a portion of this, at least, to ferrous
oxide before precipitation with sodic acetate.

Heat the acid solution to boiling, remove the lamp, add
a solution of sodic sulphite until the liquid is quite color-
less, and sodic carbonate produces a white precipitate ;
then boil the mixture as long as any odor of sulphurous
acid is evolved, nearly saturate the acid with sodic carbon-
ate, add a few drops of chlorine water, then sodic acetate
in excess, and finally more chlorine water drop by drop,
until the liquid is reddish, and boil ; the precipitate con-
tains all the alumina and phosphoric acid, mixed with but
little ferric oxide ; filter it out quickly, wash it with a lit-

§ 94. QUANTITATIVE :metiiods. 161

tie hot water, and dissolve it, without ignition, either in
nitric acid and eliminate phosphoric acid with the aid of
amnionic molybdate (§ 61, b), or in hydrochloric acid and
precipitate the phosphoric acid with magnesia mixture in
the presence of citric acid, as above.

(4.) If there is a large proportion of phosphoric acid in
the substance, and comparatively little ferric oxide and
alumina, the nitric acid solution, obtained as in 1, may be
treated with metallic tin, as described in J^.

91. Schemes for the quantitative separation of K.^ iVa.,
Ca., My,, Fe., AL, Mn., P, 0„ and SO^,

The purpose of these schemes is, to present a birds-
eye view of the various courses to be followed for the
separation of the bases and acids given in this list.

For the details of the manipulation the analyst should
always follow up the references given in the schemes and
in § 93, unless he is perfectly familiar with these details,
and knows them, as it were, by heart.

The capital letters in the schemes refer to paragraphs
in § 93, the small letters to other parts of the schemes
themselves.

162

§ 94. SPECIAL METHODS OF ANALYSIS.

PnOSPHORIC ACID IS Oli IS NOT IN EXCESS OVER THE ALUMINA AND
PERRIC OXIDE.

Divide the filtrate from the silica in three parts, a, b, and c.

1. Precipitate SO3
withBaCl, filter. (E.)

2. Precipitate P2O5
together with Fe,Ca,
etc., with NH4HO,or
NH4HO and (NH4)2-
CO3, filter. (F.)

0. Eliminate K. and
Na. as chlorides,

by treat-
ment with

milk of
lime, NH4-
HO and
(NH4)2-
CO3, filtra-
tion, evap-
oration to
dryness,
ignition.
G, 1.

/3-
by evapo-
ration to
dryness,
ignition,
addition
of oxalic
acid, igni-
tion, solu-
tion in
water, fil-
tration,

and

ignition.

G, 2.

1. First add FcsCle in
slight excess over the P2-
O5 if AI2O3 and FcaOg are
not already present in
excess (see A, 1); then
eliminate the acid,

a.
by addition

of NH4HO

in slight ex-
cess, diges-
tion, filtra-
tion, solu-
tion of pre-
cipitate in
HNO3 and
precipita-
tion of P2O5
with(NH4)2-
M0O3.

ILL

by addition
of NaHO
until nearly
neutral, pre-
cipitation
with NaC2-
H302(oruse

of NH4HO

and NH4C2-
H3O2 if alka-
lies are to
be determ-
ined in fil-
trate); dis-
solve pre-
cipitate in
HCl, precip-
itate P2O5
with mag-
nesia mix-
ture and
citric acid.
H, 2.

2. Treat filtrate from
precipitate by NH4HO in
a or NH4C2H3O2 in /3 as
under a, if it is desired
to repeat the determina-
tion of alkalies.

1. First add an accu-
jratcly titrated solution
I of FcaCls in proper
'quantity (see A, 2) if
AI2O3 and Fe203 are not
already present in ex-
cess over the P2O5; then
add NasCOg until nearly
neutral, and precipitate
Fe,Al,P205 with NaCs-
H3O2 ; dissolve precipi-
tate in HCl, divide in
halves, precipitate one-
half with NH4HO, filter,
ignite,and wei<^h Al,Fe,
P2O5. Determine Fein
other half with K2Mn2-
Og, at once, or after pre-
cipitation w'ith NH4HO
and solution in II2SO4.
(A.)

2. First Filtr. —
{From the2yr€€. by KaCr
B^O-i). Concentrate and
precipitate Mn by CI.
(C.)

3. Second Filtr. —
{From the prec. bij CI.)
Concentrate,precipitate
Ca with(NH4)2C204 (D).

4. Third Filtr.—
(From the prec. by
{NBi)^C^Oi.) Concen-
trate and precipitate
Mg. with Naali, PO4
(D).

IL

A LARGE EXCESS OF BOTU ALUMINA AND FERRIC OXIDE IS PRESENT.

Divide the filtrate from the silica in three parts, a, b, and c.

1. Precipitate SO3 with Ba-
Cl and filter. (E.)

2. Eliminate K and Na as
chlorides. See Scheme I,
a, 3.

b.

Treat this
portion as
directed in
Sclieme I
under c.

c.

Reduce the ferric to fer-
rous oxide witli sodic sul-
phite (H,3), precipitate all
Al and P0O5 together with
little Fe, and eliminate P2O5
as under a or j3, Scheme I, b.

§ 94. QUANTITATIVE METHODS.

163

III.

NO ALUMINA IS PRESENT, AND PHOSPnORIC ACID IS IN EXCESS OVER

THE IRON.

Divide tlic filtrate from tlie silica in two parts, a and b.

Determine

S03,F205,K

and Na, as

under a,

Scheme I.

b.
1. Add an aceui'ately titrated solution of FeaClg, nearly'
neutralize the solution with NasCOa, precipitate Fe and
P2O5 with NaCsHgOQ (A); dissolve the precHpitute in HCl,
divide solution in two equal portions, a and (i.

Determine Fe with per-
manganate (A.)

2^.
Determine P2O5 with (NH4)2-
M0O3 (H, 1) or citric acid and
magnesia mixture (H, 2).

3. Determine Mn, Ca, and Mg, in the filtrate from the
precipitate by NaC2H302, as in 2, 3, and 4, under c,
Scheme I.

IV.

NO ALUMINA OR MANGANESE IS PRESENT, AND PUOSPHORIC ACID IS IN
EXCESS OVER THE IRON.

Proceed as in III, except that the elimination of manganese by chlorine
may be omitted.

TO DETERMINE ALL WITHOUT DIVIDING THE SOLUTION.

1. To the filtrate from the silica add the titrated solution of ferric
chloride, if necessar.v, (see § 93, A, 2), nearly neutralize the solution with
(NH4)2C03, precipitate Fe, Al, and P2O5, with NH4C2H3O2, dissolve the
precipitate in HCl, and divide the solution in two equal portions ; pre-
cipitate one portion with NH4HO, and get total Al, Fe, and PsOs; heat
the ignited residue in a mixture of 8 parts of concentrated sulphuric
acid and 3 parts of Avater, add water, and determine Fe in this solution
with potassic permanganate (A) ; eliminate P2O5 in the other portion of
the solution, with the aid of ammonic molybdate, or magnesia mixture
in the presence of citric acid. (H.)

2. First Filtrate. {From the precip. by NRiCJIsO^.) Evaporate
to dryness and ignite the residue until ammonic salts are completely ex-
pelled; dissolve in water acidified with HCl, nearly neutralize the solu-
tion with NaaCOa, add NaCaHgOj, and precipitate Mu by CI. (C.)

3. Second Filtrate. {From the precipitate by CI.) After removing
excess of CI by heat, precipitate Ca with (NH4)2C204. (D.)

4. Third Filtrate. {From the precip. by {NEi^C^Oi). Precipitate
SOgwithBaCl. (E.)

164 § 94. SPECIAL METHODS OP ANALYSIS.

5. Fourth Filtrate. {From the preclp. 1)]] BaCl.') Kemove excess
of Ba with (NH4)2 COg, evaporate filtrate to dryuess, ignite, treat with
1120204, (see G, 2), ignite, exliaust with water, and treat this solution for
the estimation of the alkalies, as directed for the treatment of the cor-
responding solution in G, 3.

6. Dissolve the residue that has been exJiausted dy water as above, in di-
lute HCl, filter if necessary, and precipitate Mg in the filtrate with NagH
PO4 (§ 50, a).

VI.

TO DETERMINE ALL EXCEPT MANGANESE, W^ITHOUT DIVIDING THE
SOLUTION.

Proceed as under V, except that the evaporation to dryness, ignition, and
treatment with 01 for the estimation of Mn, arc to be omitted.

VII.

TO DETERMINE ALL EXCEPT MANGANESE AND PHOSPHORIC ACID, WITH-
OUT DIVIDING THE SOLUTION.

Proceed as under VI, except that no FcsCle need be added, and that one

portion of the solution of the precipitate by NH4C2H3O0 is to be used for

the estimation of the sum of the Fe and Al only, and the other portion

for the determination of Fe. (A.)

VIII.

TO DETERMINE ALL EXCEPT ALUMINIUM AND MANGANESE WITHOUT
DIVIDING THE SOLUTION.

Proceed as under VI, except that one portion of the solution of the pre-
cipitate by NH4C2H3O2 is to be used for the estimation of Fe, and the
other for that of P2O3. (A, H.)

IX.

DETERMINATION Or ALL, AND ELIMINATION OF PHOSPHORIC ACID BY
THE TIN PROCESS.

Divide the filtrate from the silica in tw^o parts, a and b.

a.

1. Precipitate
SO3 with BaCl,
and filter. (E.)

2. Eliminate K
and Na as chlo-
rides. (See

Scheme I, a, 3.)

b.

1. Treat the concentrated nitric-acid solution with
Sn, this precipitate by NII4HS, and the solution so ob-
tained with magnesia mixture (B).

2. First Filtr. (From the precip. by Sn.) Precipi-
tate Fe and Al by NallO and NaCoHgOo, dissolve the
precipitate in HOI, divide solution in two equal purts,
precipitate one part by NH4HO to get total Al and Fe,
and determine Fe in the otlier part (A).

3. Second Filtr. (From the lu-ecip. by NaOoHgOa.)
Treat tiiis for the estimation of Mn, Ca, and Mg, as in
Selieme I, under c, 3, 8 and 4.

§ 95. SOILS. 165

X.

TO DETERMINE ALL EXCEPT MANGANESE, WITHOUT DIVIDING THE
SOLUTION.

a. Eliminate P0O5 from tlic filtrate from the silica, bv means of Sn
(VIII, b).

b. First Filtr. (From tlie precip. by Sn.) Precipitate Al and Fe with
NH4HO and NH4C2H3O2, and treat this precipitate as directed for the
treatment of the correspondin*^ one by NaCaHgOa in VIII, b.

c. Second Filtr. Treat this, for the estimation of Ca, SO3, K, Na, and
Mg, as directed in Scheme V, 3, 4, 5 and 6.

CHAPTER Y.

ANALYSIS OF SOILS AND ROCKS.
I.

SOILS.

95i The following general method of analyzing soils,
by Emil WoliF, was approved at the annual meeting of
German Agricultural Chemists in Gottingen, in" 1864,
and is given in full in his work on agricultural analysis,
referred to in the preface.

In his introductory remarks, Prof. Wolff writes : " Of
course it is not essential that the experienced chemist
should follow strictly all the methods for the separation
and quantitative estimation of particular components of
the soil, that are given here as guides for the beginner
in chemical analysis, and are used by me ; those methods
may be modified in many cases without impairing the
accuracy of the analytical work. But it is necessary
that all chemists who undertake accurate analyses of
soils should agree to follow the same course in regard to

166 § 96. ANALYSIS OF SOILS AND HOCKS.

certain important points, in order that the results ob-
tained by different workers may be comparable with
each other, or possess any lasting practical, or scientific
value.

" Such essential points, concerning which agricultural
chemists should aim to agree, are, the manner in which
the sample of the soil is to be taken from the field, the
preparation of the same, and the quantity to be taken
for analysis, the manner of performing the mechanical
silt (Schlamm) analysis, the methods of determining the
coefficients of absorption of the more important elements
of plant-food, and, above all, the preparation of the solu-
tions or extracts of the soil that are to be subjected to
chemical analysis."

He says also in another place :

" Although I recognize the need of a large number of
full and complete analyses of soils, and of improving or
amplifying some of the methods given here, in order to
perfect our scientific knowledge of the soil, yet an abridg-
ment of the following course will usually answer for all
practical purposes ; for such an abridged course, it will be
sufficient, for example, to examine only that part of the soil
that is soluble in cold or hot concentrated hydrochloric
acid, with perhaps the addition of a mechanical analysis ;
but even in this case, the previous preparation of the soil
and of the solutions to be analyzed should be made in
accordance with the directions given below, at least until
other methods become as generally approved and adopted."

PREPARATION OF THE SAMPLE FOR ANALYSIS.

96. Make an excavation in the soil 30-50 cm. deep, or
tlirough to the subsoil, and 30-50 cm. square, with one
side as nearly vertical as possible, and take a slice from
this side of uniform thickness throughout, weighing 4-5
kilos. The subsoil lies below the depth generally reach-

96. PEEPAEATION OF THE SAMPLE FOE ANALYSIS. 167

ed by the plough, and is usually readily distinguished
from the upper soil by its physical characters, among
which a ligiiter color is prominent, owing to the absence
of humus. If this subsoil is to be examined, a sample
of it should be taken out in the same manner as directed
for the upper soil, to the depth of about 60 cm., and the
depth of the cavity noted.

The sample is taken, according to the object of the
analysis, either

«, from one or from several spots in the field, in order
to subject each sample to a separate analysis; or

5, for an average representation of the soil of the whole
field ; in this case, several portions of earth are taken
from points distributed in a regular manner over the
field, all of which are most carefully mixed together, and
4-6 kilos, of the mixture, free from any large stones, are
preserved as the average sample.

If the character of the soil varies materially in differ-
ent parts of the field, samples from several spots should
be analyzed separately.

A small portion of the sample should be put at once in
a well-stoppered bottle ; the remainder may be allowed
to become air-dried, by exposing it in a thin layer, in
summer, to the common temperature in the shade, or, in
winter, to that of a warm room, or a moderately warm
drying-chamber, heated to 30°-40° C. ; in either case it
should be carefully protected from dust.

At the time of taking the sample of the soil, obser-
vations should be made in regard to the following points ;

a. The geognostic origin of the soil.

h. The nature of the underlying strata, to the depth
of 1-2 metres, if practicable.

c. The meteorology of the locality — ^l:>y consulting me-
teorological records, if possible; otherwise, by the general
opinion of the neighborhood; in this connection, the

168 § 96. ANALYSIS OF SOILS AND EOCKS.

height of the locality above the level of the sea should
be noted also.

d. The management and rotation of crops in previous
years.

e. The character of the customary manuring.

/. The amount of the crops removed in the preceding
year, and, if possible, the average amount of each of the
more important crops yielded by the field.

ff. The practical judgment of neighboring farmers in
regard to the field.

Having taken the sample to the laboratory, separate
the stones and larger pebbles from the finer parts by the
hand, or by sifting with a very coarse sieve, and examine
them with reference to their mineralogical character,
weight and size, making note, in this last respect, of the
number that are as large as the fist or larger, the num-
ber as large as an egg, a walnut, hazel-nut, and pea,. or
give the percentage of each by weight.

Pulverize the air-dried soil in a mortar with a wooden
pestle, and separate the fine earth out by a sieve with
meshes 3 mm. wide ; this sieve should have a tightly fit-
ting cover of sheej)-skin stretched over a hoop, and it
should be covered in the same manner underneath, so
that no dust can escape during the process of sifting.

Wash the pebbles and vegetable fibres remaining on
the sieve with water, dry and weigh the residue, and ex-
amine the pebbles mineralogically ; the water with which
this gravel was washed should be evaporated to dryness
at a temperature not exceeding 50° C. towards the close
of the evaporation, and the residue mixed with what
passed through the dry sieve.

This sifted fi?2e earth is reserved for all the processes
hereinafter described, and is kept in well-stoppered bot-
tles, marked air-dried fine earth.

§ 97. SILT ANALYSIS, 1G9

SILT ANALYSIS.

97. This air-dried fine earth may be separated, still
further, into portions of different degrees of fineness by
a series of sieves, or, in a quicker and better manner, by
the process of silt analysis.

a. To perform this with Kobel's apparatus (fig. 6),
weigh out 30 grms. of the air-dried soil, and boil it for a
long time with water, until the lumps are completely
broken up ; the operation may be facilitated by gentle
trituration with a small pestle ; in the case of very sandy
soils, it will be finished in half an hour, but for very
heavy clay soils, two or three hours may be required.

When this is completed throw the whole mixture of
soil and water on a sieve with meshes 1 mm. wide, rinse
the residue on the sieve well with water, dry it at 100° C,
and weigh it ; that which passes through the sieve, and
the washings, are reserved for the silt analysis proper.

The water reservoir of Nobel's apparatus should hold
about 10 litres, and the siphon tube that enters it should
extend down just far enough to allow 9 litres of vv^ater,
and no more, to flow out ; the other arm of the siphon
should be 60 cm. long, and should have just as large a
bore as the tube of the funnel with which it is connect-
ed. The relative capacities of the four silt funnels, [N'os.
1, 2, 3, and 4, are 1 : 8 : 26 : 64 ; together, they hold 5
litres ; the mouth of the largest funnel where the water
finally flows out of the apparatus should be provided
with a tube drawn out to a point, that is filed off until
the orifice is of such a size that, when all the funnels are
filled with water, and the connection with the reservoir
is made as above directed, 9 litres will flow through in
exactly 40 minutes.

A large flask or beaker must be provided to receive
the water as it flows out of the largest funnel.

The fine earth, that passed through the sieve with
8

170

97. ANALYSIS OF SOILS AND EOCKS.

meshes 1 mm. wide, is stirred up with water ; in case
there is reason to suppose that funnel No. 2 will not hold
all this mixture of soil and water, a part of the latter,
holding only the finest particles in suspension, may be put
in funnel No. 3 ; then pour the rest of the mixture, just
after it has been well stirred, into the second funnel,

Fig. 6.

while any very coarse sand remaining in the beaker may
be rinsed into the first funnel ; but it is better to put the
whole in the second funnel, if possible.

All the funnels are then filled with water, the connec-
tions carefully made between them with gum tubing, and
the siphon leading from the reservoir is filled and con-
nected with the smallest funnel. As soon as 9 litres of
water have passed through, the connection with the
reservoir is closed by means of a clamp on the gum tube.

The whole apparatus is then allowed to stand about
five hours, until the solid matters in the funnels have

§ 97. SILT ANALYSIS. 17X

settled to the bottom ; then draw ojff the clear supernat-
ant liquid from each funnel with a siphon, and transfer
each portion of the sediment to a separate evaporating
dish, except that the contents of funnels 1 and 2 should be
mixed together; dry each portion at 125° C, and weigh
it. After this, ignite each one and weigh again, and.
thus determine the amount of organic matter in it.

By this operation the soil is separated into at least five
portions, of diflferent degrees of fineness,

1. The residue on the sieve.

2. The contents of funnel No. 2.

3. " " " " No. 3. ^

4. " " '^ " No. 4.

5. The sediment deposited from the water that flowed
through the whole apparatus, and the still finer portions
remaining suspended in the water even after several
hours. These two may be separately determined, if it is
desired, by collecting, drying, and weighing the sediment
that is deposited after several hours, and then estimating
the still finer portion that remains in suspension, together
with the hygroscopic water of the soil, by the difierence
between the 30 grms. of soil taken originally, and the
sum of these five residues ; then on subtracting from
this remainder the hygroscopic water, as determined in
another portion of the soil, we have the weight of the
sixth portion ; or, the fifth and sixth may be estimated
together, in a similar manner, and without collecting the
sediment deposited in the beaker.

To clarify this liquid more speedily, A. Mtiller {Jour-
nal far PraJct. Chemie, 95,92; Fresenius's Zeitschrift,
5, 243) recommends the following process. Prepare a
solution of an ammoniacal soap, with the aid of stearic
acid, ammonia, and alcohol, add it to the turbid liquid
until the mixture gives considerable foam when violently
agitated, then acetic acid until the reaction of the liquid
is decidedly acid, and stir or shake the whole vigorously;

172

§ 97. ANALYSIS OF SOILS AND EOCKS.

the fatty acid that is set free by the acetic acid envelopes
the fine particles of earth, and the flocculent sediment
can be filtered out without difficulty. The fatty acid
may then be removed from the other solid matters, with
which it is mixed, by ignition, or by treatment with alco-
hol, and the residue will represent the finest portion of
the soil.

h. The following method of silt analysis, by Dietrich
{Fresenius' s Zeitschrift, 5, 296) is preferred by some to
that described above ; the apparatus may be easily con-
structed out of the ordinary stock of the laboratory.

The water is caused to flow, under a constant pressure
of 1 metre, through a series of four tubes of different
sizes, and inclined to the horizon at different angles, as
follows ;

Number
ilietube.

Length.

Diameter.

Angle between its axis

and a

hoj'izontal plane.

1
2
3
4

17 cm.
34 "

51 "
68 "

2.8 cm.
4 "
5.2 «
6.4 "

90°
67.5°
45°
22.5°

Each tube is drawn out at one end so that a rubber
tube can be attached to it, while the other end is closed
with a rubber cork, through which a short glass tube
passes ; each tube is connected with the next larger one
by a rubber tube passing from the corked end of the
former, which is at the same time the upper end, to the
lower, tapering end of the latter, and the water flows
from the upper end of one tube to the lower end of the
next larger one. Each rubber tube is cut in the middle
of its length, and the cut ends are connected together by
a short glass tube ; each rubber tube also has a clamp on
it, by means of which the flow of the water can be regu-
lated. The 30 grms. of soil, prepared as for the silt
analysis with Nobel's apparatus, are put in the first

§ 98. THE CHEMICAL ANALYSIS. 173

tube, and the flow of the water through the apparatus is
continued until it comes away from the last tube tolera-
bly clear. The remainder of the operation is conducted
in the same manner as when using Nobel's apparatus.

THE CHEMICAL ANALYSIS.

98. The soil for tliis analysis should always be taken
in its natural, air-dried condition, without previous igni-
tion to expel the organic matter, since the ignition may
at the same time alter very materially the effect of the
agents employed for solution.

a. Hyi^roscopic water and other Tolatilc matter.—

Determine the amount of water expelled at 100° C. from
10 grms. of soil (§ 90), and then ignite the dried residue
to determine water chemically combined or otherwise re-
tained at 100° C, humus, and volatile mineral substances
(§ 91) ; the ignited residue should be treated with am-
monic carbonate, if a qualitative test reveals the presence
of carbonic acid in the soil, and carbonic acid should be
determined in the ash (§ 91, d).

A. Midler allows but little value to this estimation of
water of hydrates in the soil, and organic matter, even
when combined with the determination of carbonic acid
both before and after ignition.

h. Estimate carbonic acid in 5-10 grms. of soil, dried
at 100° (§ 60, h).

c. Determine the total nitrogen in 5-10 grms of soil,
dried at 100°, by combustion with soda-lime (§ 85).

A, Miiller mixes the soil with about an equal quantity
of caustic jDotash or soda, instead of with soda-lime, but
fills the rest of the tube with soda-lime in the usual man-
ner ; in this way he avoids the use of very long combus-
tion-tubes.

If much nitrate is present in the soil, and but little hu-

174 § 99. ANALYSIS OF SOILS AND EOCKS.

mus, it will be safer to add 0.2-0.4 grm. of pure cane
sugar to the sample in which nitrogen is determined;
otherwise some of the nitrogen may escape conversion
into ammonia; a small portion of the sugar should be
ignited by itself with soda-lime, cither to determine the
amount of nitrogen it contains, or to be sure of its free-
dom from that imj)urity.

d. In order to determine the solubility of the various
elements of plant-food in the soil, it is necessary to treat
it successively with different solvents, and with these of
various degrees of strength ; in order that the results ob-
tained by different chemists may be compared with each
other, it is absolutely essential that these solvents should
be applied in the same order and in the same manner.

A convenient and useful order is the following :

1. Cold, distilled water, '|^ saturated Avith carbonic
acid.

2. Cold concentrated liydrochloric acid (Sjx Gr. — 1.15).

3. Boiling concentrated hydrochloric acid of the same
strength.

4. Hot concentrated sulphuric acid.

5. Hydrofluoric acid.

The solutions obtained by the treatment of the soil
with these agents in succession will be found to differ
very much in their composition, and to yield data for
very interesting deductions in regard to its natural fer-
tility.

Unless, however, a very complete analysis is desired,
but one of these solutions, viz., that in cold concentrated
hydrochloric acid, need be examined quantitatively ; next
to this, the solution in hot hydrochloric acid is of great-
est importance ; we shall, therefore, consider the treat-
ment of these first of all.

Solution in Cold Concentrated Hydrochloric Acid.

99. Put 450 grms. of air-dried soil in a large, glass-

§ 99. THE CHEMICAL ANALYSIS. 175

stoppered bottle, and pour over it 1500 c.c. of pure con-
centrated hydrochloric acid (Sp. Gr. = 1.15), and shake
the mixture frequently during a digestion of 48 hours, at
the common temperature of the working-room ; then let
it stand until 1000 c.c. of at least a tolerably clear liquid
can be poured off or drawn oif with a siphon ; this quan-
tity of the solution represents ^\^oi 450 grms., or 300
grms. of the soil taken for the analysis ; dilute the liquid
with its volume of water, and filter it.

If the soil contains a very large proportion of calcic
carbonate, the cold acid solution may be filtered off after
dilution with its volume of water, and the whole quan-
tity used for the analysis, representing the whole of the
soil taken ; in this case, wash the insoluble residue care-
fully first with cold and then with hot Avater, dry it at
100° C, and weigh, to deteimine the proportion of the
soil insoluble in cold acid; 5-10 grms. of this may be
ignited, to determine the organic matter in the insolu-
ble portion ; then reserve the rest for treatment with so-
dic carbonate, to determine soluble silica, and with hot
concentrated acid.

Evaporate the solution to dryness with the addition of
a few drops of concentrated nitric acid towards the close
of the evaporation, to oxidize ferrous oxide and organic
matters, and eliminate silica (§ 58, a, 1).

Dilute the filtrate from the silica to 1000 c.c, and
analyze it according to Scheme II., § 94, taking 400 c.c.
for a, 200 for b, and 400 for c.

In ^, a slight insoluble residue often remains, on dis-
solving the precipitate by sodic acetate in hydrochloric
acid ; in this case, dry the residue, ignite it and the filter,
digest the ash a long time with concentrated hydroclilodc
acid, filter if necessary, and add the filtrate to the re-
mainder of the solution of the precipitate by sodic ace-
tate in hydrochloric acid, ignite and weigh the insoluble
residue, if there is any, and add it to the silicic acid.

176 § 99. ANALYSIS OF SOILS AXD ROCKS.

If the soil is very rich in organic matter, it will be bet-
ter to treat 500 c.c. of the solution with sodic carbonate
and potassic nitrate, or Avith chlorine, as directed in
§ 93, A, and use ^j^ of the solution finally obtained for J,
omitting, of course, the determination of the alkalies
in this portion of the solution unless the oxidation was
effected with chlorine, and ^1^ for c.

Sometimes, however, when there is not a very large
proportion of organic matter present, and the above
treatment for oxidation is not followed, traces of organic
matter are contained in the solution of ferric oxide ob-
tained in J, for estimation with permanganate; where
great accuracy is required therefore, it would be well,
after having titrated the ferric solution once, to reconvert
the ferric oxide into ferrous, with zinc or sulphurous
acid, titrate the solution again, and to repeat this until
a constant result is obtained. The same mode of pro-
cedure should be followed, also, in estimating the strength
of the permanganic solution.

In accurate soil analyses, the phosphoric acid should be
estimated twice.

In a complete soil analysis, it is desirable to determine
the silicic acid, which, after treatment of tlie soil with
cold concentrated hydrochloric acid, is soluble in a con-
centrated solution of sodic carbonate.

For this purpose, take 5-10 grms. of the residue that
was insoluble in the acid, in case of a soil rich in carbon-
ates ; or, digest 25 grms. of the air-dried soil with three
times the quantity of cold concentrated acid, 48 hours in
the cold, filter, and Avash the contents of the filter perse-
veringly, first Avith cold and afterwards Avitli hot water,
and use this residue.

Boil this insoluble substance and also an equal amount
of the original air-dried soil, Avith sodic carbonate, in tlio
manner described for the separation of sand and silica
(§ 58, a, 2). The difference between the amounts of

§ 100. THE CHEMICAL AXALTSIS. 177

silicic acid dissolved in the two cases furnishes a means
of estimating the extent of the action of the cold acid on
the silicates in the soil.
Treatment of the Soil with Carbonated Water.
100. To determine only the total quantity of organic
and inorganic matters in the soil, soluble in water con-
taining carbonic acid in solution, without reference to the
composition of the dissolved substances, put 500 gims.
of air-dried soil in a flask that can be well stoppered, and
l^our over it as much carbonated water as will make, to-
gether with the hygroscopic water in the soil, 2000 c.c.
The water should be ^|^ saturated with carbonic acid, by
saturating 500 c.c. at the common temperature and press-
ure, and mixing this with 1500 c.c. of pure water. When
thus pre2:)ared, the water is more nearly like that in the
soil, whose action we wish to imitate.

Leave the soil and water in contact with each other
three days, with frequent agitation, then pour off 1000
c.c. of as clear a liquid as possible, representing 250 grms.
of soil, and filter through a double filter, while keeping
the funnel w^ell covered with a glass plate. Evaporate
the clear filtrate to dryness at a temperature below boil-
ing, dry the residue at 125° C, weigh, ignite, and after
treatment several times with ammonic carbonate and
gentle ignition, weigh again. The difference between the
two weights gives the amount of organic matter dissolved
by tlie carbonated water.

The carbonic acid is determined in the ignited residue,
as in § 60.

If a detailed chemical examination of the solution in
carbonated water is to be made, at least 1500 grms. of
soil must be taken instead of 500, and the water in the
same proportion. After three days, pour oif 4000 c.c. of
the clear supernatant liquid, representing two-thirds of
the soil, let it stand 24 hours in well-closed and full
bottles, filter as directed above, and without disturbing
8-

178 § 100. ANALYSIS OF SOILS AND KOCKS.

the sediment at the bottom of the bottles. If a clear
filtrate is not obtamed in this way, it must be evaporated
down to 400 or 500 c.c., just barely supersaturated with
hydrochloric acid while still hot, and then filtered again.

Evaporate the solution to dryness, with the addition
of a few drops of nitric acid towards the close of the
evaporation, to peroxidize the iron and destroy organic
matter, and eliminate silicic acid. (§ 58, a^ 1.)

Treat the filtrate from the silica as in Scheme I., § 94.
Alumina, ferric oxide, and phosphoric acid, are usually
present, however, in such small quantities in this solution,
that it is hardly worth while to determine at least the
first two.

Interesting results may be obtained by the successive
treatment of the same portion of soil with carbonated
water, and a chemical examination of each solution; the
proportion may thus be learned in which the more im-
portant elements of plant-food are taken up by the suc-
cessive aqueous extracts, and data are obtained for esti-
mating, not only the general richness of the soil in
valuable elements of plant-food, such as phosphoric acid
and potassa, but also the relation between the immediate
fertility of the soil and the durability of its fruitfulness.

A very great decrease in the amount of the elements
of plant-food in the second and third extracts, as com-
pared with the first, would indicate that the fertility of
the soil would be very much lessened in a single season.
If, on the contrary, there is but little diminution observ-
ed even in the fifth extract, the power of the soil to
produce crops will probably remain about the same, year
after year, for a long time.

To obtain these successive extracts, replace the 4000
c.c. that were poured off" for the first extract, by an equal
quantity of fresh Avater \ saturated witli carbonic acid as
before, let stand three days with frequent shaking, pour

§ 101. THE CHEMICAL ANALYSIS. 179

off 4000 c.c. again, and repeat this operation for the third
and fourth time, or even more, as may be desired.

Ulbricht found, that after the third or fourth extract,
the amount dissolved, at least by distilled water free from
carbonic acid, remained nearly constant, and that the
composition of one of these last extracts would furnish
the means for estimating the lasting fertility of the soil.

It will usually answer to examine quantitatively the
first, third, fifth, and seventh extracts by carbonated
water.

Interesting results may be obtained also by treating
the soil in the manner above directed with water contain-
ing 0.5 gmi. of ammonic chloride in the litre, in addition
to the usual charge of carbonic acid.

Treatment of the Soil with Hot Concentrated
Hydrochloric Acid.

101. If the soil contained a very large proportion of
calcic carbonate, the residue insoluble in cold acid may
be treated with hot acid ; otherwise the separation of the
insoluble from the soluble part by filtration is too diffi-
cult, and it is better to begin with a fresh portion of soil.
Pour 300 c.c. of concentrated acid over 150 grms. of the
air-dried soil, or over the whole of the residue insoluble
in cold acid in case carbonates were present in large
quantity, in a large flask, add a few drops of nitric acid
to oxidize slimy matters that might obstruct the filter,
heat to boiling w^th constant agitation, and continue to
boil gently for exactly an hour ; dilute the solution with
twice its volume of water, and, after letting the mixture
stand quietly for a short time, decant the liquid into a
filter that is double at the bottom ; treat the insoluble
residue in the flask at least three times with boiling wa-
ter, filter the liquid each time, and finally bring the resi-
due itself on the filter, and wash it thoroughly with boil-
ing water.

Evaporate the solution and washings to dryness, with

180 § 102. AN-ALYSIS OF SOILS AND EOCKS.

the addition of a few drops of nitric acid towards the
close of the evaporation, to destroy organic matter and
oxidize ferrous salts, and eliminate silica. (§ 58, a, 1.)

Examine the filtrate from the silica, which is to be
made up to 1000 c.c. and well mixed, according to
Scheme II., § 94.

Or, in order to have a larger quantity of solution for
the determination of phosphoric and sulphuric acids, the
analysis may be performed by Scheme I., in which a and
h may be united, and the sulphuric acid determined as
usual, while half the filtrate from the j^recipitate by
ammonia for phosphoric acid will answer for the determi-
nation of the alkalies.

Examination of the Residue Insoluble in Hot Hydro-
chloric Acid.

102. Dry it, and remove it from the filter as completely
as possible, burn the latter, and weigh ash and residue,
and separate the carefully prepared mixture of the two
into three accurately weighed portions of 10 grms. (a),
10-15 grms. (^), and 15-20 grms. (e).

a. Ignite this portion, to determine the amount of min-
eral matter insoluble in the hot acid.

b. In this portion determine the silica soluble in car-
bonated alkali. (§ 58, c/, 2.)

c. Pour five times its weight of concentrated sulphuric
acid over this portion, heat until the excess of acid is
removed, and the residue forms a light, dry powder ; the
evaporation of the acid should be performed slowly and
with constant stirring, and should require from six to
eight hours. Moisten the residue freely with concentrat-
ed hydrochloric acid, remove this acid by long heating in
the water-bath, boil the residue repeatedly Avith water to
which a little hydrochloric acid has been added, filter, and
wash the insoluble residue carefully.

Examine the solutions and washings, after concentra-
tion, according to Scheme VII., § 94.

§ 103. THE CHEMICAL ANALYSIS. 181

The amount of lime is usually small. Wolff directs
that the filtrate from the precipitate of calcic oxalate be
evaporated to dryness, the residue ignited gently in a
platinum dish, to expel ammoniacal salts, dissolved in di-
lute acid, and any silicic acid that may appear as an in-
soluble residue be filtered out; then add ammonia in
slight excess to the filtrate, filter out any flocculent pre-
cipitate of alumina that may also appear, and finally de-
termine sulphuric acid with baric chloride.

This treatment of the soil with sulphuric acid serves
to determine the amount of clay in it, and Wolff has
found, by repeated trials, that the clay is completely
decomposed if the operation is carefully perfonned. He
gives importance to the determination, for it furnishes data
for controlling the results obtained by the silt analysis,
and' because it gives valuable information in regard to
the degree of insolubility of the other constituents of the
soil, and particularly the alkalies.

The process is a good connecting link between the
treatment with hydrochloric acid on the one hand and
hydrofluoric acid on the other.

Examination of tlie Residue Undecomposed by Sul-
phuric Acid.

103. a. Dry this residue at 100°, burn the filter by it-
self, and weigh the ash and residue ; mix them well to-
gether, and, in half of the mixture, determine silica solu-
ble in alkaline carbonates. (§ 58, a, 2.) The silicic acid
thus found, together with the small quantity in the
hydrochloric and sulphuric acid solutions, gives, in con-
nection with the alumina found in the same solutions,
an approximate estimate of the pure anhydrous clay in
the soil. This amount of silicic acid is, in general, too
large in proportion to that of the alumina, for a part of
it was combined with ferric oxide, lime, etc.

The clay that is decomposed by the sulphuric acid

182 § 103. ANALYSIS OF SOILS AND ROCKS.

alone is very nearly pure, while it is that which is dissolved
by the hydrochloric acid that contains too much silica.

Ignite the other half of the residue, to determine the
amount of mineral matters insoluble after treatment with
sulphuric acid.

Pulverize the ignited mass very finely in an agate
mortar, separate the finer from the coarser portions by
levigation (§ 36) with distilled water, pulverize the coarse
part again, and repeat the levigation ; when in this way
the whole is reduced to the finest possible powder, eva2>
orate the water to dryness with the matters in suspension
in it, weigh out 3-4 grms. of the well-dried residue, and
treat it with hydrofluoric acid or amnionic fluoride
(§58,c).

Examine the solution thus obtained according to Scheme
VII., § 94. The determination of ferric oxide will, how-
ever, be necessary, only when the precipitate by ammonia
is yellowish or reddish.

If, as is usually the case, the solution is found to con-
tain only traces of lime and magnesia, the amount of
feldspathic minerals and of pure quartz sand in this in-
soluble part of the soil can be estimated from the amount
of alkalies found ; and, from the amount of aluminic sili-
cate, it may be judged how perfectly the clay was de-
composed by the previous treatment with sulphuric acid.

h. According to A. Miiller, the relative proportion of
silicates and quartz sand in a soil can be determined with
accuracy by digestion with phosphoric acid at a certain
temperature; all the silicates are decomposed by this
treatment, and the silica is separated in a gelatinous form
while the quartz sand remains unchanged.

For this purpose a syruj^y acid is required containing
40-45°l g of anhydrous acid ; it may be obtained by con-
centrating the commercial acid.

The insoluble residue to be treated with the acid must
be very finely pulverized, but it need not be levigated ;

§ 104. MISCELLANEOUS ESTIMATIONS. 183

the amount of pliosplioric acid required depends upon
the amount of silicates present, and at least 15-20 grms.
should be taken for 0.5-1.0 grm. of the substance. The
mixture is heated in a platinum dish in an air-bath to
190-200° C, and digested five or six hours at this temper-
ature, while constantly stirred with a platinum spatula.
The resulting mass is boiled several times with water
containing 1"! ^ of sodic hydrate, the clear liquid decanted
off each time, and the sandy residue itself is finally
brought on the filter and washed carefully with acid, alkali,
acid again, and finally with water, ignited and weighed.

MISCELLANEOUS ESTIMATIONS.

104. a. IlumuSo — Weigh out 5-10 grms: of the air-
dried soil, pour over it 200 c.c. of water in the flask of
the apparatus for determining carbonic acid (§ 60, b), and
30 c.c. of concentrated sulphuric acid; shake the mixture
gently and let it stand some time until it has become
quite cold, meanwhile changing the air in the flask sev-
eral times by blowing into it, so as to remove all the car-
bonic acid expelled from carbonates in the soil by the
stronger acid.

Now, put 7-8 grms. of coarsely pulverized potassic di-
chromate in the flask (or, better still, 5 grms. of pure
chromic acid), or such a quantity that there will be 17
parts of chromic acid for one of organic matter, as de-
termined, ap2)roximately at least, in the beginning, by ig-
nition (§ 98, a) ; apply a gentle heat, and proceed to
collect the carbonic acid evolved as in § 60, i, except that
a U tube filled with iron wire should be interposed be-
tween the flask and the U tube ff, to absorb chlorine,
and except, also, that no nitric acid need be added to
the substance. Towards the close of the operation, boil
the contents of the flask five minutes, and finally draw
air throusfh in the usual manner. The carbonic acid is

184 § 104. ANALYSIS OF SOILS AND EOCKS.

set free by the oxidation of the humus by the chromic
acid.

Since humus contains on an average SS"! ^ of carbon,
multiply the quantity of carbonic acid found by 0.4702,
for the amount of humus.

The difference between the sum of the humus and the
nitrogen and the total loss suffered on ignition (§ 98)
gives the amount of water, chemically combined or other-
wise retained at 100° C.

Some information in regard to the nature of the or-
ganic matter, and the extent to which decay has pro-
gressed, may be obtained by comparing the amount of
humus, or of the carbon in it, with that of the nitrogen,
by a microscopic examination of the various products
of the silt analysis and by the loss suffered by these c:a
ignition, and also by the following tests.

1. The reaction of the soil or of the humus contained
in it, which is tested by allowing moistened lumps of the
soil to remain in contact with carefully prepared blue and
red litmus-paper ; a change from blue to red may be
caused by carbonic acid, but, if the red color remains
after the paper is thoroughly dry, the change was due to
acids of the humus, unless the soil gives the same reaction
after gentle ignition, in which case it may have been
caused by acid sulphates.

2. Mix 100 grms. of the soil with 200 c.c. of a stand-
ard ammoniacal solution of calcic nitrate of such a
strength that 200 c.c. contain 1 grm. of lime, and an
amount of ammonia chemically equivalent to this amount
of lime. After frequent shaking of the mixture in the
course of 24 hours, filter, and determine lime in a measur-
ed quantity of the filtrate ; the lime that is missing was,
according to Knop, absorbed by the humus, and may be
taken as an approximate measure of the amount of the
same.

3. To determine the amount of organic matter, mainly

§ 104. MISCELLANEOUS ESTIMATIONS. 185

in the form of humus, that is extracted from the soil by-
water or alkaline solutions, the following method is given
by Schulze. Boil 10 grins, of soil 15 minutes with 200
c.c. of a solution containing 0.5" |„ of potassa, bring the
volume of the whole to 250 c.c, pour the liquid on a dry-
filter, or through dry, fine-grained sand with which the
throat of the funnel is stopj^ed ; put 4-6 c.c. of the filtrate
in a flask^f about 200 c.c. capacity, dilute with about 100
c.c. of water, and determine organic matter in 100 c.c. of
this solution by means of standard solutions of potassic
permanganate and oxalic acid (§ 91, e).

h. Ammonia* — The amount of ammonia existing al-
ready formed in soils is nearly always very small, since it
is so readily converted into nitrates.

To determine it by Schlossing's method (§ 47, b), treat
50 grms. of soil with 40 c.c. of a cold saturated solution
of sodic hydrate. After 48 hours remove the acid from
under the bell-jar, titrate it, stir the soil in the watch-
glass, put another measured portion of acid in the projDcr
vessel, and, after 48 hours, titrate this also with the
standard sodic solution. If no more ammonia was set
free during the second period, the first determination
may be considered , snfiicient ; if more was set free, it
should be added to the first quantity found, and a new
portion of acid should be put in, in the place of the last,
and tested after 48 hours.

It may also be desirable to estimate the ammonia that
is set free on heating the soil with magnesia. Pour 500
c.c. of water containing 5 grms. of freshly ignited mag-
nesia over 100 grms. of soil, mix the whole well together,
and proceed to distil off the ammonia (§ 47, c).

Probably no great reliance can be placed on any method
of determining ammonia in soils.

c. Nitric acid. — The accurate determination of nitric
acid is not difficult, as the nitrates are so easily extracted
from the soil by water.

186 § 104. ANALYSIS OF SOILS AND ROCKS.

To 1000 grms. of the soil add water enough to make
2000 c.c. with that already in the soil, shake the mixture
frequently in the course of 48 hours, decant and filter
1000 c.c. through a dry filter, add some sodic carbonate
to the filtrate, evaporate the solution to a small bulk on
the water-bath, and divide the residue into two equal
parts. Determine nitric acid in each portion, represent-
ing 250 grms. of soil, in the usual manner (§ 62 ci).

d. Chlorine* — To determine this, add enough water to
300 grms. of the air-dried soil to make 900 c.c. with what
is already contained in it, shake the mixture frequently
in the course of 48. hours, decant and filter 450 c.c. of the
liquid, add a little sodic carbonate to the filtrate, evapo-
rate to about 200 c.c, filter again, supersaturate the fil-
trate, which represents 150 grms. of soil, with nitric acid,
and precipitate the chlorine in the acid solution with
argentic nitrate (§ 63). Treat the precipitate as one pro-
duced in the presence of organic matter.

e. Sulphur. — It often happens that a much larger
amount of sulphuric acid is found in the soil after ignition
than before, indicating that a notable quantity of sul-
phur exists there as sulphuret, or in some organic combi-
nation. To determine the total amount of sulphur in the
soil, mix with 50 grms. of it, 1-2 grms. of pure saltpetre,
moisten the mixture in a platinum dish with a solution of
pure potassic or sodic hydrate, free particularly from sul-
phates, dry, and heat gradually to a red heat ; when the
mass is cool, boil it with dilute hydrochloric acid to
which a little nitric has been added, evaporate to dryness,
and eliminate silica in the usual way, but without weigh-
ing it ; add water to the filtrate from the silica, and pre-
cipitate sulphuric acid with baric chloride.

/. Hydratcd aluminic and ferric oxides.— To deter-
mine the quantity of these substances, that, according to
Knop, play so im2)0itant a part in the absorbent action

§ 104. MISCELLANEOUS ESTIMATIONS. 187

of the soil for valuable elements of j^lant-food, treat 100
grms. of the soil with 200 c.c. of a hot solution contain-
ing in one litre 100 grms. of tartaric acid, 10 grms. of
oxalic acid, and ammonia in slight excess ; shake the mix-
ture frequently for 15 minutes, filter, and determine
aluminic and ferric oxide in a measured quantity of the
filtrate (§ 52). The oxalic acid in the solvent serves to
prevent lime from being taken up by the tartaric acid.
In order to prevent alumina also from being dissolved,
Mtiller recommends the use of Seignette salt instead of
ammonic tartrate.

g. Ferrous oxide. — To determine this at least approx-
imately, pour 60 c.c. of hot concentrated hydrochloric
acid over 30 grms. of soil in a flask ; after having added
a few crystals of sodic carbonate, if the soil contains but
little carbonate, close the flasic with a cork through which
passes a short tube bent at a right angle, put the flask in
an inclined j^osition on the lamp-stand, and boil the mix-
ture some time. Add a considerable quantity of ammonic
chloride to the solution, whereby the tendency of the
ferrous oxide to absorb oxygen is very much lessened,
dilute with a large quantity of hot water, almost neutral-
ize the acid with ammonia, and precipitate the ferric
oxide in the solution with as little sodic acetate as possi-
ble (§ 93, -4, 1) ; filter the hot liquid rapidly through a
large, coarse filter, and wash the contents of the filter
several times with hot water; heat the" filtrate and wash-
ings to boiling, add some hydrochloric acid, oxidize the
ferrous oxide by the addition of a few crystals of potassic
chlorate, remove the lamp, and precipitate this solution
with sodic acetate, filter, wash, and weigh. The ignited
residue is ferric oxide, from which the corresponding
amount of ferrous oxide can be calculated.

188 § 105. ANALYSIS OF SOILS AXD ROCKS.

ABSORPTIVE PROPERTIES OF THE SOIL.

105. To determine the coefficients of absorj)tion of the
soil for the more important elements of j^lant-food, treat
125 grms. of the air-dried soil with 600 c.c. of a ^1^^,
atomic solution, that is, a solution containing in 1 litre ^ [.^
of an equivalent expressed in grammes, of ammonic chlo-
rid<} ; shake the mixture frequently during a cold digestion
of 24 hours, decant and filter as large a portion of the
liquid as possible, and determine the loss of the salt in a
measured aliquot part of the filtrate. In some cases it is
desirable also to make a complete analysis of this filtrate
in order to learn what elements have taken the place of
the ammonium in the solution.

Make similar experiments with potassic chloride, mag-
nesic chloride, calcic chloride, hydric disodic phosphate,
sodic chloride, and sodic silicate.

Or, according to Knop's method, dissolve together po-
tassic and calcic nitrate, common potassic phosphate, and
magnesic sulphate, in a litre of water, in such a propor-
tion that the solution shall contain 1.5 grms. of each com-
pound, estimated as anhydrous salt. Treat 125 grms. of
soil with 500 c.c. of this solution, shake the mixture fre-
quently during 24 hours, filter oif 300 or 400 c.c, and
make a complete analysis of the solution, according to
Scheme T., a and i, and deteimine chlorine in the usual
manner in another portion of the same solution (§ 63) .

STATEMENT OF THE RESULTS OF THE ANALYSIS.

106. The following Scheme is intended to assist the
analyst in putting together the results of a soil analysis ;
it is conformed mainly Avith the directions given by
Wolff, and the percentages, though hypothetical, do not
differ much from the average results of the later analyses
of soils that have been made ; as the plan is given merely

/

§ 106. STATEMENT OF EESFLTS OF ANALYSIS. 189

for the purpose of illustrating the manner of stating the
results of the analysis, many of the determinations which
are described in the foregoing pages are not noticed here.
With this partial guide, no difficulty will be found in
stating the whole result of the w^ork in an intelligible
manner.

MECHANICAL ANALYSIS.

100 parts of tlie air-dried soil yielded

I

Water, expelled at 100^ 9.34

Residue on 3 mm. sieve, 6.05, containing volatile matter 0.1

" " 1 " " 7.69, " " " 0.86

Silt in Funnel No. 2, 34.95, " " " 3.73

" " " " 3, 17.7, " " " 3.16

" " " " 4, 5.65, " " " 0.82

81.38
Fineclayand finest sand, 18.62 " " " 2.48

100.00 Total loss on ignition of

soil dried at 100* 10.15

190

§ 106. ANALYSIS OP SOILS AND EOCKS,

CHEMICAL ANALYSIS.
100 parts of the soil dried at 100° yielded

5 =^5
So r

Soluble in water 2.10

Soluble iu alkali 1.25

containing nitrogen .

Acids of humus ..,..3.25

Humus coal 1.75

Other organic matter 1 . 25

Ammonia 0.02

Nitric acid 0.009

Total nitrogen 0.0288

Water chemically combined or

otherwise retained at 100° .1.221

7.500

0.01

0.0165

0.0023

Carbonic acid (det. in another portion) 0 . 14 '

Lime 0.17

Magnesia 0.50

Ferric oxide 5.05

Manganic oxide traces

Alumina 4.20

Potassa ■ 0.06

Soda 0.02

Phosphoric acid 0.15

Sulphuric acid 0. 04

Silica 0.35

Chlorine (det. in aqueous solution) 0.073

iO?T53

Deduct oxygen equivalent to the chlorine .003

10.75

2>

Co

©hi "
2 o

(B^ fLime 0.31

Magnesia 0.96

And so on, as in the statement of the analysis of the
solution in cold acid, with the exception of Chlorine,
and the addition of Silica, (dissolved out of the resi-
due insoluble in hot acid, by boiling sodic carbon-
ate)

15.24

>. •* r Volatile matter expelled on ignition 1 .82

■^Q Lime 0.21

Magnesia 0.31

Ferric oxide 1.03

Alumina 1.76

, Potash 0.12

^ ^ Soda 0.20

Phosphoric acid. 0 . 15

Silica, in solution 0.14

" (dissolved out of the residue insoluble

InHaSO* byhoilingNaaCOa 4.56

as

si

'C.J,
So"

acccJ

10.30

s.::^

tcC o
s o

Lime

tVAO.P.

Ferric oxide

0.00

Alumina

Potnssa

6.91

3.20

Soda

2.11

Silica

44.00

56.22

§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 191

100 parts of soil dried at 100° C. contain of clay AI2O3 2Si02,

2H2O, estimated from tlie alumina and silica dissolved by acids

(See Table III).

a. In the hydrochloric acid solutions 4.56

h. " " sulphuric acid solution 4.41

100 parts of soil dried at 100° contain of
a. Fotassa feldspar^ KaOjSSiOa, AlaOsjoSiOa, estimated from the

potassa in the solution by hydrofluoric acid. (See Tabic III.).18.94
6. Soda feldspar^ Na20,3SiOo, AlaOsjSSiOa, estimated from the

soda in the solution by hydrofluoric acid 17.85

c. Clay^ undecomposed by the previous treatment with sulphui-ic

acid, estimated from the alumina in the solution by hydro-
fluoric acid in excess of what is required for the feldsjDars 0.30

d. Pare quartz saiid^ estimated from the silica in excess over what

is required for the feldspars and clay 19.11

(Estimated also from the determination made with the aid of
phosphoric acid).
100 parts of soil dried at 100° C. yielded to water }{ saturated
with carbonic acid
Volatile matter, expelled on ignition of the residue left by evapo-
ration of the extract 0.15 .

Mineral matters 0.19

0.34
THE PHYSICAL QUALITIES OF THE SOIL.

107. Experiments for testing the physical qualities of
the soil, and for comparing different soils in respect to
these qualities, should be made with soils of the same de-
gree of dryness and mechanical division, and with tolera-
bly large quantities, and the observations should be made
under circumstances resembling those as closely as j^ossi-
ble, by which the soil is affected in the field. The fol-
lowing methods have been carefully tested by Wolff
himself, and he vouches for their reliability.

The soil must be comj^letely air-dried, pulverized in a
porcelain mortar with a wooden pestle, or rubbed between
the hands to break up the lumps that were formed in
drying, and passed througli a sieve witli meshes 3 mm.
wide.

192 § 107. ANALYSIS OF SOILS AND EOCKS.

a. Relation of the Soil to Vapor of Water. — 1,
Power of retaining liygroseopic water in its pores. — This
is measured to some extent by the determination of hy-
groscopic moisture (§ 98). The j)roj)ortion of humus
remaining about the same, the power of the soil to retain
moisture is very closely related to the amount of clay it
contains, while this j)ower is greatly increased by an
increased proportion of humus.

2. It may be interesting to observe the relation Of tllis
property of the air-dried soil to the temperature.—
For this purpose, spread a layer of soil, accurately weigh-
ed, about 3 mm. thick over the bottom of a shallow zinc
tray, and note the changes in weight from day to day,
when it is exposed to direct sunlight while protected
from currents of air, or when exposed to a temperature
of 20°, 30% and 40° C.

Also, expose the soil to cm atmosphere that is saturated
with moisture^ by putting it in the same shallow tray to-
gether with a shallow vessel of w^ater, under a bell-jar,
and weighing it three or four times every 24 hours. An
empty tray of the same size should be put under the same
bell-jar, and any changes in the weight of this deducted
from the differences in the weight of the other.

Sandy soils and loams usually become nearly saturated
in an experiment like this, in the first 24 hours, and
change but little in weight thereafter.

The quantity of water absorbed varies of course with
the temperature, and with the kind of soil ; but these
variations are confined within narrower limits than when
the soils are exposed to the air under ordinary circum-
stances. The amount of water absorbed from this satu-
rated atmosphere ranges between 0.2 and 2.5° 1^, of the
weiglit of the completely dry soil.

The same soil, in its tray, may he exposed to the night
air^ to determine the amount of water that it will con-
dense from the atmospliere under these circumstances ;

§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 193

careful observations should be made, at the same time, of
the temperature, the clearness of the sky, and the
amount of the dew-fall, and the experiment should be
performed over a grass plot as well as over a freshly
stirred soil.

With an average dew-fall, the amount of water taken
up by a soil above what it contains in the air-dried state
varies, with different kinds of soil, between 0.4 and 1.8° [^
of the weight of the completely dried soil.

Finally, to test the effect of the depth of the soil on
its power of absorbing moisture under these different cir-
cumstances, several trays or boxes, of say ^l^, V\^^ 3, and
6 cm. deep, and 5 cm. square, may be filled with air-dried
soil, in all cases equally dry and finely pulverized, and
the whole exposed to the ordinary atmospheric influ-
ences, or to a saturated atmosphere, or to the night air,
in the manner directed above.

By such experiments we may determine how much
moisture is absorbed by layers of soil of different thick-
nesses within a certain length of time, how far the moist-
ure penetrates into different soils in equal times, and how
long a time is required to saturate layers of different
thicknesses in a saturated atmosphere.

b. The Relation of the Soil to Liquid Water ix its
Pores.— 1. To determine the power of the soil to retain
liquid water in its pores, construct a zinc box, 17 cm. deep,
and 3 cm. square, and pierce its bottom with numerous
small holes ; lay over this bottom a piece of moistened
fine Imen, and Aveigh the box ; then put in a small quan-
tity of the properly dried and pulverized soil, taj) the
box gently on the table a few times, and proceed in the
same manner until the box is full, and weigh again.
Then immerse the bottom of the box in water to the
depth of 3-4 mm. ; the water appears at the surface of
the soil sooner or later, according to the nature of the
latter ; let the apparatus vemain in the water until |t suf-
9

194 § 107. ANALYSIS or SOILS AND EOCKS.

fers no further change m weight, and then calculate the
amount taken uj) by 100 parts of the air-dried soil.

As this box, with its wet soil, is used subsequently for
experiments in the course of which tlie soil is dried
again, this trial may then be repeated ; some soils shrink,
while drying, to a greater extent than others, and it will
be found that, in this second trial, the power of holding
water will not be the same as at first. The difference,
however, is but slight.

The power of a soil to hold liquid water increases with .
the proportion of humus, but diminishes as the quantity
of clay increases. A strong clay soil may retain 27.3" |^,
a moderately heavy soil 30-31° |^, a sandy loam 33-36°!^,
a black loam, rich in humus, 41° 1^. When some soils,
that had been tested as above, were tested also in their
natural position in the field, after a rain of 14 days, when
they might be supposed to be saturated, they were found
to contain 10" j^ less than was indicated by the results of
experiments in the laboratory ; hence, the determinations
made with small quantities in zinc boxes, appear to have
value only in so far as they enable us to compare the
water-holding powers of different soils.

2« To determine the readiness with which water evap-
orates from the soil, the wet or damp soil may be ex-
posed, in a shallow tray, to the air, at the common sum-
mer temperature, or at that of the laboratory ; but so
long as a considerable proportion of w^ater is present, the
rate of evaporation remains about the same for all soils,
provided only that the same amount of surface is exposed;
it is also very slow, months being required to bring 100-
150 grms. of soil, in a layer no more than 4-6 cm. thick,
to the condition of air-dried soil.

When, however, natural circumstances are more closely
imitated, and a sufficiently thick layer of soil is experi-
mented with and exposed to the usual alternation of direct
sunlight and shade, the characteristic differences of soils

§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 195

appear. For a standard of comparison it would be well
to carry on, simultaneously, one or two similar trials with
soils of a marked character, such as a very strong clay
soil and a very sandy one, that have been tested before
in this respect.

To make the determination, use the zinc box filled ^v^th
wet soil, that was obtained in testing the water-holding
power ; put each box with its contents in a second box
of thick pasteboard, into which it just fits, and then put
all these pasteboard boxes close together in a third
wooden box, just as deep as the zinc boxes; provide the
wooden box with a cover, in which holes are so cut that,
when the cover is on the box, only the surface of earth in
each zinc box is exposed.

Put the whole where the sun's rays can fall on the soil,
and weigh each zinc box with its contents every two or
three days, and during a length of time varying from, two
to four weeks, according to the weather ; frequent ob-
servations of the temperature and the state of the sky
should be made, while the evaporation is going on.

It will be observed that, in the beginning, the rate of
evaporation is about the same for all the varieties of soil
under examination, even when exposed to the rays of a
hot sun ; after a time the sandy soils begin to lose weight
more rapidly than those in which clay or humus pre-
dominates ; the difierence increases up to a certain point,
and then begins to diminish, until, after a time, the rate
of evaporation is nearly the same again for all ; this con-
tinues for a time, and then the clay and humus soils begin
to lose water more rapidly than the light loam, because
the latter is, by this time, nearly air-dry.

It is of course more important to watch carefully the
rate of evaporation, from the time when it begins to differ
in the different soils, to the time when it again becomes
about the same for all.

196 § 107. ANALYSIS OF SOILS AND KOCKS.

3. To determine the ease with which water perco-
lates through the soil, construct a ziac box about 25 cm.
high aud 3 cm. square, with a funnel-like bottom; put
some cotton in the bottom, so as to close up the throat
of the funnel, and fill the narrow tube, and extend out a
little at the mouth of the latter. Fill the funnel above
the cotton with coarse quartz sand, moisten the cotton
and sand with water, and weigh the apparatus ; then
carefully fill the box with the properly prepared earth,
putting in small quantities at a time, and tapping the box
on the table after each portion is added ; when the box is
filled to within 9 cm. of the top, w^eigh the whole again ;
then, just saturate the soil by carefully pouring on water
in small quantities at a time, until it appears at the
bottom ; when it has ceased to drop through, weigh the
box and its contents again, and the result may be used
to confirm that obtained before for the water-holding
power of the soil.

Now carefully fill the box with water to within 1 cm.
of the top without disturbing the surface of the soil,
cover with a glass plate, and observe how long a time is
required for 50 c.c. of water to pass tlirough. If the
operation is repeated, by filling the box with water again,
after the first quantity has passed through, it will be
found that a somewhat longer time is I'equired ; three
such tests may be made, and the mean of the three re-
sults taken.

4. To determine the rapidity with which water will
move upwards in the soil, fill a glass tube about 80 cm.
high and 1.5-2 cm. in diameter, graduated in cubic cen-
timetres, and closed at its lower end with a piece of fine
linen that is tied over the end, with the air-dried soil, tap-
ping the tube gently on the table while filling it ; then
immerse the lower end of the tube in water 3-4 mm.
deep, and observe how long a time is required for the
Avater to rise to a height of 70 or 80 cm., or how high

§ 107. THE PHYSICAL QUALITIES OP THE SOIL. 197

the water will rise in 24 or 48 hours ; it will be found
to rise more slowly in humus and clay soils than in light,
sandy ones.

5. The rapidity with which water will make its way
downwards in the soil may be determined in the same
tube, partly filled with a fresh quantity of earth ; fill the
tube above the soil with water to the depth of 4-8 cm.,
and note the time required until it has reached a given
depth, or how soon the water disappears from the surfjice
of the soil, r.nd also how far a given quantity, that is in-
suflScient to make its way through and moisten the soil
quite to the lower end, will penetrate downwards.

It will be found that the same quantity of water will
go furthest in a fine loam or a sandy soil.

c. The Rel4.tiox of the Soil to Heat. — 1, To
determine the power of the soil to absorh heat, fill a
cubical zinc box, about 6 cm. square, with soil, expose it
several hours to the direct rays of the sun on a hot day,
carefully observe the temperature in the sun during the
experiment, and the elevation of temperature in the up-
permost centimetre of the soil. The zinc box should be
inclosed in a box of thick pasteboard, and tins in a wooden
box, to prevent access of heat at the sides.

It may also be interesting to observe the heating power
of the sun's rays on the soil, while it is in a more or less
moist condition, say with 5, 10, or 20° 1^ of water, more
than that naturally present in the soil. Such determina-
tions may be made by exposing about 50 grms. of the
moistened soil for several hours in a glass flask to the
direct rays of the sun, and noting the changes of tem-
perature.

2. The power of the soil to conduct heat may be de-
termined by putting the same box, as used in the previ-
ous experiment, into hot water, and observing how long
a time elapses before the temperature of the earth in the

198 § 107. ANALYSIS OF SOILS AND EOCKS.

centre of the box has reached a given point, say 70^ or
80° C.

3. The power of the soil to retain heat may be de-
termined by exposing the box of heated soil, obtained in
either of the preceding experiments, to the common tem-
perature of the air in the shade, and observing how long
a lime is required for the soil in the middle of the box to
cool to the temperature of tlie air, or to a given point, as
20° or 25° C.

The behavior of the soil with respect to the heat of the
sun and of the atmosphere is of great agricultural im-
portance, and should be more carefully examined than
has hitherto been the case, by the careful performance of
experiments like those described above, and by series of
observations on the temperature of the soil in tlie field at
various depths, ranging from 3 cm. down to one metre or
more.

d. The Specific Gravity of the Soil. — 1. This may
be determined in the usual manner for a powder (§ 35, 5).

A soil rich in humus is specifically the lightest, and
coarse sandy soils are the heaviest.

2. The absolute weight of the soil is determined by
filling a glass vessel, or a cubical zinc box, whose weight
and capacity are known, with it, tapping the vessel occa-
sionally on the table while filling it, and weighing it. The
weight of a cubic metre or a cubic foot can then be cal-
ctdated from the result; the apparent specific gravity
can be estimated by the ratio between the weight of this
volume of soil and that of an equal volume of water.

3. The apparent specific gravity of the soil dried at
100° C. may be estimated by subtracting the volume of

. the water contained in the quantity of air-dried soil that
was weighed in this experiment from the volume of the
soil, and then a volume of water equal to the remainder is
taken for the divisor, and the weight of the soil dried at
100° for the dividend.

§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 199

4. The porosity of the soil, or the ratio between the
volume of the solid particles and that of the spaces in it
filled with air or moisture, is estimated by dividing the
apparent specific gravity of the soil, dried at 100°, by the
real specific gravity. Or if, for example, 2.5445 = the
real specific gravity of a certain soil, and 1.099 its ap-
parent specific gravity, then from the proportion,

2.5445 : 1.099 = 100 : 43.2,
we get the volume of the solid particles in 100 parts of
the soil, and 100-43.2 = 56.8 = the volume of the pores.

The porosity of the soil, just as it lies in the field, may
be estimated in a similar manner, by taking as the volume
of the soil the space that was occupied by the quantity
taken out to be weighed.

To determine the volume occupied by the soil when
completely saturated with water, determine the volume
of 40-50 grms. of the air-driecl, pulverized soil in a
graduated tube, that was filled with the earth in small
portions at a time, with occasional tapping on the table,
shake the soil up well with water containing 0.5° 1^ of am-
monic chloride ; then let the whole stand quietly, while
the solid particles collect together in the lower part of
the tube, and observe the volume occupied by this wet
soil. By dividing the second volume by the first, the re-
sult is put in a convenient form for comparison.

e. Consistency, Tenacity, and Adhesive Power of
THE Soil. — The consistency of the soil when dry, its
tenacity, and the force with which it adheres to wood and
iron, are very important qualities ; but it is hardly pos-
sible, by any of the methods in use for estimating them,
to get even approximately accurate results with small
quantities of soil. The following methods were devised
and used by Schiibler thirty years ago.

1. To determine the consistency of the soil, or the
force with which its particles cohere together when dry,

200 § 108. ANALYSIS OF SOILS AND KOCKS.

knead a small portion of it into a thick dough with wateiv
and, with a spatula, make several prisms 5 cm. long, and
1 cm. square on the end ; let them dry in the air, and
then observe what weight must be laid on the back of a
knife in order to force it through each one. The same
prisms may be used to determine how much the soil
shrinks on drying, by noting the difference between their
lengths when wet as at first, and after they are dry.

2. To determine the force with which the soil adheres
to wood or iron, fill a cubical zinc box about 6 cm. square
and deep, whose bottom is j)ierced with small holes, and
covered with a piece of linen, with the soil, shaking it
down frequently while filling ; then immerse the bottom
of the box in water, and, w^hen no further increase of
w^eight is observed, lay a smooth piece of beech wood, 3
cm. square, on the wet surface of the soil, press it down
for the space of ten minutes, by a w^eight of 100 grms.,
attach the disk to one arm of a balance, and observe what
weight must be put in the pan connected with the other
arm, in order to detach the disk from the soil. Try a
similar experiment witli a disk' of iron.

EXPERIMENTS WITH PLANTS IN CONNECTION WITH ANALY-
SIS OF SOILS.

108. The further development of soil analysis on one
hand, and its simplification on the other by eliminating
useless or unnecessary determinations, can be accom-
plished only by combining suitable experiments with
modes of culture and manuring, and growling plants, with
accurate analyses of the soils used.

In the field but little can be done in this way, since so
much care and labor are required, in order to obtain a
tolerably fair representative sample of the soil, even of a
small plot.

iSTot seldom, however, a more luxuriant vegetation is

§ 108. EXPERIMENTS WITH PLANTS AND SOILS. 201

observed in one part of a field than in another, although
the nature of the soil and the mode of treatment are ap-
parently the same throughout ; in such a case, much may
possibly be learned, by a careful comparison of the amounts
of the crops taken from the two parts of the field, and a
search for the cause of the difference by a careful exami-
nation of the soil. Of course the nature of the subsoil
should be ascertained, down to the depth of a metre or
so, in order to be sure that the cause of the phenomenon
does not Ife there, perhaps in some accumulation of water,
or a great difference in the mechanical or physical charac-
ters of this subsoil.

Actual experiments with manures and growing j^lants,
to be combined with soil analysis, are best made in boxes
of soil that has been carefully sifted and mixed ; a perfect
sample of such a soil can be obtained without difficulty.

The wooden boxes to contain the soil for these experi-
ments may be made abo^.t one metre deep, and half a
metre square, and with several holes through the bottom.
They should be set in the ground in a grass plot, so that
they will project but 3-5 cm. above the surface. The
soil with which they are to be filled should be pulverized
when in a very moderately moist condition, by rubbing
it between the hands, or with a wooden pestle in a porce-
lain mortar, and passed through a sieve with meshes 6-8
mm. wide ; an ample quantity of it should be provided,
so that there may be enough for the analysis and for all
possible contingencies, besides what is required to fill up
the box.

To fill the box, put a layer of gravel 5-8 cm. thick
over the bottom, and then add the soil, pressing it down
gently, as it is put in in small portions at a time ; then
pour a quantity of rain-water over the soil, equal to
about half that which it can retain in its pores ; stir up
the surface and fill with more soil, up to the edge of the
box, and, if possible, before sowing the seed, or putting
9*

202 § 108. ANALYSIS OF SOILS Ai!«-D llOCKS.

in j)laiits, let the whole stand several weeks, so that it
may settle together and assume a perfectly natural con-
dition.

If the boxes, when put in place, are not surrounded by
grassy turf, the same plants as those cultivated in them
should be grown around them, so that there can be no
disturbing influences from fresh soil.

When the seed is to be sown, put in more fresh soil if
it is necessary, in order to bring the surface up even w*ith
the edge of the box. In sowing the seed, and in the sub-
sequent cultivation of the plant, the usual rules of good
culture should be observed as far as possible, as respects
depth of sowing, distance apart of the plants, and other
matters. For experiments with the cereals, which are of
the greatest importance, oats and rye are best, since these
plants are less liable to disease, or to be destroyed by
birds.

The foUoAving are a few of the great number of inter-
esting experiments that can be performed in these boxes
of prepared soil.

Three or four soils may be prepared, differing great-
ly in the amount of sand and clay they contain, but
closely resembling each other as regards the lime and hu-
mus. Kot only the quantity of the crop should be ob-
served, but also its quality^ such as, in the cereals, for
example, the proportion of grain, straw, and chaff, of
light and heavy grains, the specific gravity of the grain,
the number of the stalks and the degree of maturity at-
tained by them, the weight of the stubble and main roots,
and the proximate chemical composition of the different
parts of the j)lant.

With such observations as these, combined with an ac-
curate knowledge of the composition of the soil, we
should soon learn whether any direct relation exists be-
tween the proportion of plant-food in the soil, that is
soluble in water or cold or hot hydrochloric acid, and

§ 108. EXPERIMENTS WITH PLANTS AND SOILS. 203

the quantity or quality of the crop, or whether, as is
probably the case, the proportion between the clay and
these soluble substances, or, in other words, the physical
character of the soil, exerts a controlling influence on its
fertility.

It would be well to jierform three experiments of the
same character with each kind of soil, partly for the pur-
pose of securing greater certainty in the results, and
partly that the same soil may be used afterwards for other
experiments.

To test the question whether the substances in the soil
tliat are soluble in pure or carbonated water exert any
essential influence on its immediate productiveness, a trial
may be made with a soil in its natural condition, and with
the same or a similar soil, after it has been exhausted with
water in the manner described for the preparation of an
aqueous solution for chemical analysis (§ 100). As, how-
ever, it would be very inconvenient to exhaust such a
quantity of soil in this way, as would be required to fill
one of the boxes, this experiment may be performed with
but 7-10 kilos, of soil, in smaller boxes, or in glass
vessels. The plants should be watered with distilled
water during the progress of the experiment.

Valuable results may be obtained from experiments in
which equal quantities of assimilable plant-food are added
to different varieties of soil.

The action of a full and complete provision of the ele-
ments of plant-food on one kind of plant grown in the
different soils, should first be examined. For such a
complete manuring, we need only to mix together acid
potassic phosphate, calcic nitrate, j)otassic nitrate, and
magnesic sulphiite, so that the relative proportions of
the bases in the mixture will be the same as in the ash
of the plant to be cultivated.

For this purpose, the boxes and soils employed in pre-
vious years for trials with soils containing different

204 § 108. ANALYSIS OP SOILS AND ROCKS.

amounts of sand and clay may be used ; one box of each
kind of soil should have nothing added to it, so as to have
a standard with which to compare the effect of the ma-
nuring in other soils of the same nature. From the aver-
age crops of the preceding year in all the boxes, an esti-
mate may be made of the quantity of plant-food to be
added.

The soil to be manured is taken out of the box to the
depth of 30 cm. ; ^ |^ of this is intimately mixed with the
aqueous solution of the salts to be added, and this in its
turn is intimately mixed with the remaining ^|j of the
soil, by rubbing the two together carefully between the
hands ; the whole is then put back into the box.

Instead of the solution of the above salts, the actual
practice with manures may be more closely imitated by
making an aqueous extract of a superphosphate, deter-
mining the amount of phosphoric acid in the solution, and
dissolving therein the 2:)roper amounts of crude potassic
chloride, sodic nitrate, and magnesic sulphate.

In a similar manner, the effect of an increased propor-
tion of humus in the soil may be studied, by letting some
sawdust of a soft wood, free from resin, partly decay,
making an aqueous extract of this, or of some other suit-
able substance rich in humus, and mixing this solution
with the soil in the way already described.

Other matters that might be profitably studied in this
connection are, the effect of lime^ of the concentrated
commercial manures, and the relation between the co-
efficients of absorption of the soil for the various ele-
ments of plant-food, and its fertility.

§ 109. MARL. 205

II.

ROCKS AND THE PRODUCTS OF THEIR WEATHERING.

109. The object of analyzing a rock, for agricultural
purposes, may be to estimate the total amount of its con-
stituents, or to determine its solubility and the readiness
with which it would be disintegrated and converted hito
soil on exposure to the air. The method of the analysis
would be much the same as that already described for the
analysis of soils. A qualitative examination should pre-
cede the quantitative one, in order to learn the best way
of bringing the mineral into solution, as well as what
substances arc to be separated and determined.

The examination of the products of the weathering of
a rock should be conducted in the same manner as a i-egu-
lar soil analysis, by treating it with the same solvents in
the same succession.

The three more important substances that come under
this head are marl, limestone, and clay, and some special
directions for the analysis of each may be useful.

MARL.

As this substance is used by the farmer in its natural
condition, it should be taken in a similar condition, for
analysis, viz., air-dried and unignited. If taken fresh
from the pit, it should be allowed to lie for a long time
exposed to the air on filter-paper, until thoroughly dry.

The most useful of the determinations mentioned below
are those of phosphoric acid and the alkalies, and the me-
clianical analysis.

The mechanical mialysls. For this, which is of much
importance, since the value of a marl usually depends
largely on the fineness of the division of its particles,
treat 30-50 grms., according to the amount of calcic car-

206 § 109. ANALYSIS OF SOILS AND EOCKS.

bonate contained in it, with dilute hydrocliloric acid in a
flask, as long as there is any effervescence, wash the resi-
due, boil it half an hour with water, and then subject it
to the silt analysis (§ 97).

Or, if it is desired to determine the fineness of division
of the calcic carbonate in the marl, the whole may be
subjected to the silt analysis without previous treatment
with acid, and then the carbonate can be determined in
the contents of each funnel.

If the marl does not fall to a fine powder in water, it
must first be sifted, as directed for the preparation of the
soil for the silt analysis.

For practical purposes, the following rough method of
estimating the fineness of the marl will often answer.

After treating 10 grms. of the marl with hydrochloric
acid as long as there is any effervescence, i:)our a consid-
erable quantity of water over the residue, with constant
stirring, let the sand and heavier particles settle, and de-
cant the turbid liquid holding clay in suspension ; repeat
the same operation with the residue several times, until
the water is clear after the sand settles to the bottom,
collect the latter on the filter, ignite, and weigh as coarse
sand.

The chemical analysis.

a. Water. — Dry about 10 grms. of the substance at
100° C, and determine the loss of weight.

h. Carbonic acid. — Determine this in 2-4 grms., as di-
rected in § 60.

For practical purposes, the following method will usu-
ally yield sufiiciently accurate results.

Weigh out 2-3 grms. of the marl in a flask of about
100 c.c. capacity, moisten it with a little water, carefully
lower into the flask a small test-tube, ^|j filled with hydro-
chloric acid, in such a way that no acid can escape into
the flask, and weigh the Avhole ; then cause the acid to
flow out of the test-tube into the flask by inclining the

§ 109. MAEL. 207

latter, and, while the effervescence continues, let the flask
lie in an inclined position, with the end of the test-tube
partly stopping up its mouth. When the effervescence
lias ceased, blow air into the flask to remove the carbonic
acid gas, weigh the whole again, and count the loss as car-
bonic acid ; the results w^ill be within 0.25° 1^ of the truth.

c. Lime and Magnesia. — Digest 2-3 grms. of the well-
pulverized marl with dilute hydrochloric acid, and exam-
ine the solution more particularly for lime and magnesia,
as under b, Scheme lY., § 94.

d. Phosphoric acid and the alkalies. — Allow 300 c.c.
of concentrated hydrochloric acid (Sp. Gr. = 1.15) to act
on 100 grms. of the well-pulverized marl in a large flask,
for 48 hours at common temperatures, with frequent agi-
tation; (or, take 120 grms. of soil and 360 c.c. of acid, if
ferric oxide and alumina are to be determined, and esti-
mate them in ' |g of the solution obtained ; this detennina-
tion, however, will not generally be important).

Decant the solution from the insoluble residue, dilute
with some water, filter, put the insoluble residue on the
filter, and wash it first with cold and afterwards with hot
water. Evaporate the filtrate to dryness, and remove
silicic acid.

Examine the filtrate from the silica as under b, in
Scheme I, § 94.

If the marl contains a large proportion of clay, some
of the phosphoric acid may remain undissolved by the
cold concentrated acid. In this case, boil about 50 grms.
of the marl one hour with 150 c.c. of concentrated acid,
filter, eliminate silica, and proceed to determine phosphoric
acid, as above.

The insoluble residue, left after treatment of the marl
with cold acid, and composed of clay and sand, is dried
in the air-bath, left for a considerable time expoced to the
air, and weighed. If from this we subtract the weight
of coarse sand, obtained by the rough method in the

208 § 109. ANALYSIS OF SOILS AND HOCKS.

mechanical analysis, we h^ve left the amount of fine sand
and clay.

Treat this residue in the same manner as directed in
§ § 102 and 103 for the treatment of the corresponding
part of the soil.

e. A determination of humus is generally unnecessary,
but if desired, can be conducted as directed in § 104.

f. A determination of nitrogen will rarely be needed,
but may be made in the usual manner, with 5-10 grms.
of the marl.

g. Some marls, particularly such as are lich in clay, and
contain but little sand, are much more efiective after hav-
ing been gently ignited. To test the marl in this respect,
heat it to a low red heat in a muffle, with free access of
^ir, and then make an aqueous extract of the ignited mass
by treating 500 grms. ot it with 2000 c.o. of distilled
water, with frequent agitation during a cold digestion of
48 hours. Then filter off " 1^ of the solution, or 1600 c.c,
for the determination of the alkalies ; evaporate this solu-
tion to dryness, eliminate silica in the usual manner, and
estimate the alkalies in the filtrate from the silica

(§ 93, G-).

Another portion of 100 grms. of the ignited marl may
be treated with 300 c.c. of concentrated hydrochloric acid
in the cold, in the manner already directed, to estimate
phosphoric acid, and, if desired, the alkalies again.

h. Analyses of the green sand marl of New Jersey.
(Cook.)

Carbonic acid 2

Lime 2.4 1.0

M:i<?nesi:x 0.4 2.0

Ferric oxide 8.3 21.3

Alumina 6.1 8.0

Potasli 2.5 7.1

Sulpliuric acid 0.9 0.4

Plio.sphoric acid 1.4 1.3

Silica [soluble] 20.2 45.9

Silica [insoluble sand] 49.9 4.0

Water 7.1 8.1

99.4 99.1

§ 1]0. LIMESTOXE AND LIME. 209

LIMESTONE AND LIME.

llOt a. If it is desired to examine the changes that a
limestone has midergone in weathering, or to ascertain
what it contains that may contribute to the fertility of
the soil, it should, of course, be taken in its natural, air-
dry, unignited condition.

Pulverize it, and treat from 150 to 300 grms., according
to the proportion of clay or other silicates present, Avith
cold and hot concentrated hydrochloric acid, with sul-
phuric acid, and so on, in the manner directed for the
analysis of soils. The cold hydrochloric acid dissolves
all the carbonates, commonly all the phosphoric acid, but
only a small portion of the alkalies, even if a considerable
amount of these is present. But this small quantity that
is taken into solution should be determined, and the esti-
mation can be effected, after removal of the silica, in the
usual manner (Scheme I., a or ^, § 94).

The residue, insoluble in cold hydrochloric acid, is of
great importance, agriculturally considered, for it is not
seldom rich in potassa, and it should be examined with
the aid of the silt analysis, as well as of hot hydrochloric
acid, sulphuric acid, and hydrofluoric acid (§ § 101, 102,
103). In one case, over 50" ]„ of potassic feldspar was
found in the sandy insoluble residue of a dolomitic lime-
stone ;.in another case little but pure quartz.

h. By " burning " the limestone, itis essentially changed
with respect to the solubility of its constituents, and par-
ticularly the alkalies, which become soluble in larger
measure. Therefore, when a limestone is to be applied to
the soil after being burned, it should be burned before
being analyzed ; this may be accomplished by igniting it
in a Hessian crucible through the bottom of which a hole
has been broken, until, after cooling, a piece of it falls
completely to a fine powder when moistened with about
a third of its weight of water.

210 § 110. A2fA.LYSIS OF SOILS ANT> EOCKS.

1. Ill this burned limestone, determine the alkalies
soluble in water by treating 150 grms. with 1500 c.c. of
distilled water, with frequent agitation during a digestion
of 24 hours. Then pour off 1000 c.c. of the supernatant
liquid, as clear as possible, filter, if the liquid is not per-
fectly clear, remove silica as usual (§ 58, a), by evapora-
tion to dryness and treatment with hydrochloric acid,
and eliminate the alkalies as chlorides (§ 93, G).

2. Digest another joortion of 100 to 150 grms. of the
burnt lime, according to its richness in silicates, 48 hours
in tlie cold, with tliree times its weight of concentrated
hydrocliloric acid, filter the mixture, and wash the resi-
due, first with cold, and then with hot water. Determine
phosphoric acid and the alkalies in this solution (Scheme
I., § 94) ; no ferric chloride need be added.

It sometimes happens that a considerable separation of
gelatinous silica renders the filtration of the hydrochloric
acid solution very difiicult. In this case, evaporate the
whole mixture to complete dryness, moisten the residue
with concentrated acid, let it stand awhile, boil with di-
lute acid, filter, and examine this filtrate for phosphoric
acid and alkalies, as above. The solution Avill contain all
that would ordinarily be dissolved by both cold and hot
hydrocliloric acid.

Treat the residue, insoluble in cold hydrochloric acid,
with hot acid, if not already so treated, and then with
sulphuric and hydrofluoric acids (§ § 101, 102, and 103).

e. To determine whether a limestone will yield good
mortar lime, digest 4-5 grms. with dilute hydrochloric
acid, evaporate the whole to dryness, after adding a few
drops of nitric acid, boil the residue with acidified water,
filter, wash, ignite, and weigh. A good limestone, for
this purpose, should not leave more than 5 to 10° ]„ of in-
soluble matter.

The solution may be examined for alumina, ferric oxide.

§ 110. LIMESTONE AXD LIME. 211

lime, and magnesia, according to Scheme I., § 94 ; man-
ganese need not be noticed unless a qualitative analysis
reveals its presence in considerable quantity.

A determination of carbonic acid may be made to con-
trol the results of the other part of the analysis.

All the bases found should be calculated as carbonates
in making up the final statement.

d. To determine whether a limestone will make a good
hydraulic cement, the course described in the preceding
paragraph should be followed ; but the alkalies should be
determined also, and the residue, insoluble in hydrochloric
acid, should be examined with the aid of sulphuric and
hydrofluoric acids (§ § 102 and 103). 50-60 grms. of the
stone should be taken for treatment with hydrochloric
acid. And, as the chemical analysis alone will not furnish
pei-fectly safe information in regard to the fitness of the
stone for the purpose in question, portions of it should be
ignited at various temperatures, and the resulting lime in
each case pulverized and made into little balls with water,
either alone or with sand, and tested under water, to see
whether it hardens properly.

e. If the cement already prepared is given for exami-
nation, it Avill be important to determine the amount of
gelatinous silica set free by the hydrochloric acid, as well
as the lime, alumina, and alkalies. 20-25 grms. of sub-
stance will usually answer for the analysis, since the stone
is rendered more soluble by the ignition that is required
to convert it into cement.

Boil the residue, that is insoluble in hydrochloric acid,
with sodic carbonate (§ 58, a^ 2), pulverize what is in-
soluble in this agent very finely, and treat it with hydro-
fluoric acid.

212 § 111. ANALYSIS OP SOILS AXD ROCKS.

CLAY.

111. This should be taken for analysis in its natural,
air-dried condition, and examined by the same processes
as have been given for the mechanical analysis of soils,
and their treatment with acids. Different clays are very
differently affected by these agents.

Conclusions in regard to their agricultural value must
be based upon their relative solubility in the acids used,
and the composition of the part that is soluble in hydro-
chloric acid, and of that which is made soluble by treat-
ment with sulphuric acid.

For technical purjioses it Avill usually answer to treat
10-15 grms. of the clay with 6-8 times its weight of con-
centrated sulphuric acid, evaporate the mixture to com-
plete dryness, exhaust the residue w^ith dilute hydrochloric
acid, eliminate silicic acid from this solution, and estimate
alumina, ferric oxide, manganese, lime, magnesia, and the
alkalies, according to Scheme I., a and c, § 94, omitting
the estimation of phosphoric acid, and consequently the
addition of ferric chloride ; determine also the silica solu-
ble in alkaline carbonate in the residue that is insoluble in
hydrochloric acid above.

Burnt clay may sometimes be profitably applied as a
fertilizer, or an amendment. The examination of such a
clay should be conducted in the same manner as described
for burnt marl (§ 109,/); particular attention should be
paid to the amount of alkalies soluble in water, and in
cold and hot hydrochloric acid.

The proportion of phosphoric acid is not usually any
larger than in arable soils.

§ 112. FARM- YARD MAXURE. 213

CHAPTER VI.

FERTILIZERS.

I.

PRODUCTS OF THE FARM-YARD.
FARM-YARD MANURE.

112. In the examination of farm-yard manure, the part
soluble in water, and that which is insoluble in this agent,
should each be examined by itself, for it is important to
know the relative proportion and composition of these two
portions.

To procure a sample of the manure, take several small
portions from different parts of the pile, mix them all
carefully together, breaking up the lumps while working
the mass over, and preserve 3-4 kilos, for examination.

a. Water. — Dry 1000 grms. of this in the drying-
chamber, powder the residue as much as possible, or cut
it up with shears, w^eigh the whole, dry about 50 grms.,
accurately weighed, at 100° C, and calculate the loss of
weight for the whole 1000 grms. Grind this diied sub-
stance to a powder in a steel mill.

b. Organic matter. — Ignite 6-8 grms. of this powder
with the usual precautions, including the determination
of carbonic acid and coal (§ 91).

c. Carbonic acid. — Determine this in 5 grms. of the
powder (§ 60).

d. IVitrogen. — Determine this in 1 grm. of the powder.
The small amount of nitric acid in the manure will be al-
most completely converted into ammonia during the com-
bustion, in the presence of so large a proportion of car-
bonaceous ororanic matter. The nitrogen in the amnionic

214 § 112. FERTILIZEES.

carbonate, that is volatilized during the process of dry-
ing, and which is determined in the aqueous extract of a
portion of the original manure, should be added to that
obtained by combustion with soda-lime, in order to get
the total nitrogen.

e. Ammonia. — ^Determine this by the distillation of
15-20 grms. of the dried and ground manure, with 1 grm.
of freshly ignited magnesia, and water, and the estimation
of the ammonia in the distillate by titration (§ 47, c).

/. Sulphur aud sulphuric acid, — Determine total sul-
phur in the manure by fusion of 3-4 grms. of the powder
with potassic nitrate (§ 92).

g. Aqueous extract of the manure. — Pour 3000 c.c. of
water over a second portion of 1000 grms. of the fresh
manure, mix the whole well togetlier, let the mixture
stand quietly several hours, and decant the supernatant
liquid. In order to wash the residue without using too
much water, put it in a large funnel, which is stopped in
the throat with asbestus, and below with a cork, press it
down, pour water over it, and work the whole over gently
with a pestle ; after a time, remove the cork, and let the
liquid run off, and repeat the operation until tlie water
that passes away is almost colorless. Reserve the residue
in the funnel for further treatment.

Filter the whole quantity of the liquid with which the
fresh manure was treated through linen, make the volume
of the filtrate and washings up to 6000 c.c, and, if neces-
sary, filter again through paper.

1* Ammonic salts. — Determine volatile ammonic salts
(ammonic carbonate) in 300-600 c.c. of the aqueous ex-
tract, by distilling off about "I3 of it in the j^roper appa-
ratus (§ 47), without adding any alkali, and titrate the
distillate with the standard sodic solution as usual.

Determine 7ion-volatUe ammonic salts by adding 1-2
grms. of freshly ignited- magnesia, or 10-15 c.c. of milk of

§ 112. FAEM-YAKD MANURE. 215

lime to the remainder of the liquid in the retort, distilling
off ^la of the water, collecting the ammonia in the usual
manner, and titrating the distillate.

The total amount of ammonia in the aqueous extract
may be determined also by Schlossing's method ; evapo-
rate 200 c.c. of the liquid down to 50 c.c. after adding a
slight excess of hydrochloric acid, and proceed with this
concentrated solution in the usual manner (§ 47, b).

2. Nitric acid. — To determine this in the aqueous ex-
tract, evaporate 500 c.c. down to a small bulk, and pro-
ceed with this concentrated solution according to Schloss-
ing's method (§ 62, a).

3. Total amount of dry substance in solution. — ^Evap-
orate the remainder of the extract to dryness in a weighed
platinum dish, on the water-bath, and determine the total
amount of matters in solution.

4. Organic matter. — Ignite 3-4 grms. of this residue,
to determine organic and inorganic matter (§ 91), and
determine carbonic acid and chlorine in the ash (§ 60, c).

5. Carbonic acid.^ — ^Determine this in 2-3 grms. of the
residue obtained in 3 (§ 60).

6. Nitrogen. — ^Determine this in 1 grm. of the residue
obtained in 3, by combustion with soda-lime (§ 85).

7. Chlorine. — This may be partially volatilized in the
process of incineration ; an accurate estimation of it, there-
fore, requires its determination in a portion of the aqueous
extract itself. 100 c.c. of this maybe taken, or 0.5-1
grm. of the residue obtained in 3, dissolved in water.
Add nitric acid to the solution, in slight excess, and pre-
cipitate chlorine with argentic nitrate ; treat the precipi-
tate as directed for the case in which much organic matter
was present in the solution (§ 63).

Instead of following this course, a small portion of the
residue obtained in 3 may be fused with potassic nitrate
before precipitation with argentic nitrate (§ 92).

216 § 112. FERTILIZERS.

8. Ferric oxide, etc. — Ignite the remainder of the
residue obtained in 3, dissolve the ash in hydrochloric
acid, eliminate silica by evaporation to dryness, and exam-
ine the filtrate from the silicic acid according to Scheme
L, § 94.

A. The total residue, insoluble in water, obtained in </,
is dried in the steam-chamber, exposed to the air 24
hours, and weighed in this air-dried condition ; then cut
up the fibrous parts of it with the shears, and grind the
whole to a fine powder in the porcelain mortar or steel mill!

1. Water. — In 10 grms. of this powder determine hy-
groscopic water by heating to 110° C

2. Organic matter. — Ignite the dry residue obtained
in «, and determine the loss (§ 91), and determine car-
bonic acid and chlorine, if desired, in the ash.

3. Nitrogen. — To determine the nitrogen in undecom-
posed organic matter in the manure, a part of which might
be insoluble in water, and hence found here, ignite 1-2
grms. of the powder with a considerable proportion of
soda-lime (§ 85).

4. Ferric oxide, etc. — Ignite 30-40 grms. of the
powdered insoluble residue in a platinum dish, and in
3-6 grms. of the properly prepared ash (§ 123, c), accord-
ing to the proportion of sand present, eliminate silica and
sand, and analyze the remainder according to Scheme I.
or II,

§ 113. URINE.

217

Analyses of farm-yard manure by Yoelcker.

Water

Soluble orgiinic mattei-i

Mineral matter soluble in water.

Silica (sola ble)

Calcic phosphate, 3CaP04.

Lime

Maj^iiesia

Potassa

Soda

Sodic chloride

Sulpliuric acid

Carbonic acid (and loss). . .

Insoluble organic matter^ ,

Mineral matters insoluble in water.,

Silica (soluble)

Silica (insoluble, and sand)...

Ferric oxide and alumina

Lime

Magnesia

Potixssa

Soda

Sulphuric acid

Phosphoric acid

Carbonic acid (and loss)

^Contains nitroo-cn .

Free ammonia. . .
Ammouiacal salts

Fresh.

0.237
0.299
0.006
0.011
0.573
0.051
0.030
0.055
0.218

0.964
0.418
1.120
0.143
0.099
0.019
0.061
0.178
0.484

66.17

2.48

Rotted.

1.54
25.76

0.254
0.383
0.117
0.047
0.446
0.023
0.037
0.058
0.106

1.4^
1.010
0.673
1.667
0.091
0.045
0.038
0.063
0.274
1.295

4.05

100.00

0.149
0.494
0.340
0.880

75.42
3.71

0.47

12.82

6.58

100.00

0.297
0.309
0.046
0.057

FRESH ANIMAL EXCREMENTS.

URINE.

118. The following method is designed more particu-
larly for the analysis of the urine of herbivorous animals,
but it may be applied in the examination of that of carniv-
orous animals and man, also.

a. Specific Gravity. — Determine this in the usual man-
ner by comparing the weights of equal volumes of the
urine and of water (§ 34), or with the urometer, a species
of liydrometer constructed expressly for thig purpose;
10

218 § 113. FERTILIZERS.

when this instrument is used, all foam must bo carefully
removed from the surface of the liquid, by filter paper.

A difference of 4° C. in the temperature of the liquid
usually makes a difference of about 1° in the reading of
the urometer.

The specific gravity of urine ranges between 1.01 and
1.04.

h. Total amount of dry substance in solution. — De-
termine this by evaporating a weighed quantity in a cur-
rent of dry hydrogen in such a manner as to estimate the
ammonia that is expelled at the same time (§ 90, d). Take
4-6 c.c. of the urine, accurately weighed. The evapora-
tion to dryness is completed in 4-5 hours.

In human urine, that has an acid reaction due to acid
sodic phosphate, the ammonia may be assumed to have
been derived from urea, and by multiplying the amount
of it by 1.765, the corresponding amount of urea will be
obtained. But in the urine of herbivorous animals the
ammonia resulting from this decomposition must be esti-
mated by the difference between the ammonia set free on
evaporation to dryness, and that found in the urine by di-
rect determination. Generally, however, these quantities
of ammonia are very small, and can be left out of consid-
eration.

The non-TOlatile matter in this residue left on evapora-
tion is determined by evaporating a fresh quantity of
100 c.c. of the urine in a platinum dish, and igniting the
residue (§ 91, 1) ; determine carbonic acid in the ash in
the usual manner.

c. Carbonic acid (free and combined). — Determine this
in two portions of 100 c.c. of the fresh urine. To one
portion add baric chloride containing ammonia in excess,
and to the other baric chloride alone ; heat both mixtures
nearly to boiling, collect the precipitates on dried and
weighed filters, wash them, and dry them at 100°, weigh,

§ 113. rmxE. 219

and determine carbonic acid in 1-2 grms. of each precipi-
tate in the usual manner ; the first precipitate contains the
total carbonic acid, the second only the combined.

d. Nitrogen. — The residue left in the boat in h may be
used for the determination of nitrogen, or another portion
of 5-10 c.c. of the urine may be acidified with oxalic acid,
mixed with ignited gypsum, and evaporated to dryness.
In the former case this second residue will contain only so
much of the nitrogen as Avas not expelled in the form of
ammonia during the desiccation ; in the latter, the oxalic
acid will prevent the escape of any nitrogen as ammonia.
The dry substance may be completely rinsed off the sides
of the dish with some of the soda-lime used in the com-
bustion.

Or, this method of Voit may be used. Weigh out
about 5 c.c. of the urine, mix it in a shallow dish with
a sufiicient quantity of fine quartz sand to absorb it all,
put the dish under the receiver of an air-pump, and ex-
haust the air ; the whole becomes quite dry in a few hours
and may be pulverized easily, and completely loosened
from the sides of the dish and mixed with the soda-lime.

The combustion may be performed in a short combus-
tion-tube and very rapidly, without fear of losing any of
the ammonia.

e. Actual ammonia. — ^Determine this by Schlossing's
method in 20 c.c. of the urine, after filtration to remove
slimy or sedimentary matters (§ 47, V). In the fresh urine
of horned cattle, the actual ammonia does not amount to
more than 0.009-0.01° |„, but in human urine it ranges as
high as 0.078 to 0. 143° [.

/. Complete analysis of the ash. — Evaporate 200-500
grms. of the urine to dryness, incinerate the residue, and
examine the ash as directed in Scheme IV., § 94. The ash
of the urine of herbivorous animals is poor in alkaline
earths, and 8-10 grms. will be required for their determi-

220 § 113. FEKTILIZEIIS.

nation. In the urine of ruminants, phosphoric acid is
found in hardly determinable quantity, while in that of
swine and often of calves, it is present in larger quantity,
and should be estimated.

g. Chlorine and urea. — These are determined with the
aid of the standard solution of mercuric nitrate. The
urine must first be freed from phosphoric and hippuric
acids.

Acidify 200 c.c. with nitric acid, boil the mixture to ex-
pel the carbonic acid, neutralize the nitric acid w4th
freshly ignited magnesia, and cool the liquid to the tem-
perature of the room, by immersing the flask in cold wa-
ter ; transfer the liquid to a graduated cylinder, rinse the
flask into the cylinder and bring the volume of its con-
tents to 220 c.c; add 30 c.c. of an aqueous solution of fer-
ric nitrate of such a degree of concentration that, with
this quantity of the solution added, the salt will be shghtly
in excess ; the excess may be recognized by a weak reac-
tion of the solution on a slip of filter paper soaked in a
dilute solution of potassic ferrocyanidc ; too large an ex-
cess of the ferric salt will be indicated by a re-solution of
the precipitate that was formed at first, on its addition ;
filter the liquid immediately through a large, dry, ribbed
filter, and to 150 c.c. of the filtrate add 50 c.c. of a solu-
tion of baryta mixed with a little calcined magnesia, filter
again, and for each determination of sodic chloride and
urea take 15 c.c. of this filtrate, corresponding to 9 c.c. of
urine.

1. Chlorine (common salt). — Acidify exactly 15 c.c. of
the liquid with a drop of nitric acid, and allow the stand-
ard solution of mercuric nitrate to flow in from the burette,
with constant stirring until a permanent turbidity ap-
pears. A mere opalescent appearance of the liquid, which
may be presented even in the beginning, is easily distin-
guished from the cloudy turbidity which is the real indica-
tion of saturation.

§ 113. UKIxN'E. 221

Estimate the amount of sodic chlorine or of chlorine on
the basis of the standard of the solution already determ-
ined (§ 86).

2. Urea. — In a second portion of 15 c.c. of the liquid,
proceed to determine urea with tlie same standard solution
(§ 86). Subtract from the total amount of standard so-
lution required the amount used in 1, and also make the
correction required for dilution of the solution.

h. Hippuric acid. — Evaporate 200 c.c. of the urine
down to 50 C.C.J and precipitate the acid as directed in §
76. It may be well to first digest the urine with animal
charcoal in the proportion of 2 grms. of charcoal to 10 c.
c. of the liquid, in order to decolorize it.

There are usually only traces of uric acid in the urine
of herbivora, and it need not be estimated ; but in the
urine of carnivora, the proportion of uric acid generally
exceeds that of the hippuric.

According to the process of Meissner and Shepai d, for
separating these two acids, evaporate the urine until it be-
gins to crystallize, add so much absolute alcohol to the hot
liquid that a further addition causes no more precipitation,
let the mixture cool, and filter it ; the best absolute alcohol
must be used, and it must not be spared, else succinic
acid may remain in solution with the hippuric and cause
trouble. Evaporate the alcoholic solution, at first in a
flask on the water-bath, until all the alcohol and tlie water
are expelled and only a brown syrup remains, that solidi-
fies to a crystalline mass on cooling ; extract this mass,
while yet warm and liquid, with ether and a few drops of
hydrochloric acid added after the ether, agitate the mix-
ture violently, and repeat the process two or three times
with fresh portions of ether. If the alcohol and water
were not carefully removed in the preceding evaporation,
some of the urea will pass into this ethorial solution.

Collect all the etherial extracts, distil off most of the
ether, and let the rest evaporate spontaneously in the air.

222 • 8 li;

FERTILtZEILS.

riippuric acid appears then in the form of liandsome
crystals. If the crystals are not colorless, or they are not
readily formed, dilute the residue, left by the evaporation
of the ether, with water, boil the mixture with lime-wa-
ter, filter, concentrate the colorless filtrate, and jjrecipitate
the hippuric acid by hydrochloric acid in excess.

i. Phosphoric acid. — 1. This may be determmed di-
rectly in the urine, with the standard uranic solution.
Filter the urine, if necessary, add 5 c.c. of sodic acetate
to 50 c.c. of the filtrate, and titrate the mixture witli
uranic acetate as usual (§ Gl, c).

2. To obtain a more accurate determination, add tlic
magnesia mixture to 50 c.c. of the clear urine, collect and
wash the precipitate in the usual manner, dissolve it, with-
out drying, in acetic acid in not too great excess, di-
lute the solution to 50 c.c. with water, add 5 c.c. of the
solution of sodic acetate, and titrate as before, with the
uranic solution (§ 61, c).

3. To determine tlie phosphoric acid that is combined
with alkaline earths only, to 100-200 c.c. of the urine, ac-
cording to its strength, add ammonia until alkaline reac-
tion ensues, let the mixture stand 12 hours, and collect
and treat the precipitate in the manner described in 2.
In another precisely equal quantity of urine, the precipi-
tate by ammonia is ignited and weighed ; the amount of
magnesic pyrophosphate in this mixture may be estimated
by multiplying the amount of phosphoric acid in it, as de-
termined above, by 2.1831, subtracting the sum of the
pliosphates from this product, and multiplying the re-
mainder by 2.5227. If it is desired to determine lime and
magnesia directly, dissolve the mixture of the phosphates,
obtained above by precipitation ^ith ammonia, without
drying it, in as small a quantity of acetic acid as possible,
precipitate the lime by ammonic oxalate, and the mag-
nesia as phosphate again by excess of ammonia.

§ 114. SOLID EXCREMENTS. 223

Tc. Sulphuric acid. — Heat 50-100 c.c. of the urine, add
some nitric acid, and then baric chloride in slight excess
(§ 59).

I. Sulphur* — To determine total sulphur, mix 50 c.c. of
the urine in a silver crucible with solid caustic potash and
a little saltpetre; evaporate the mixture cautiously to
dryness, ignite the residue strongly until it is quite white,
exhaust it with water, and determine sulphuric acid in the
filtered solution, in the usual manner.

m. Carbon and Hydrogen. — Absorb 10 c.c. of the urine
by fine quartz sand that lias been previously boiled with
acid, washed, and ignited, dry the mixture, and bnrn it
with plumbic chromate. (See Fresenius's Quantitative
Analysis.)

SOLID EXCREMENTS.

114. The solid excrements of the herbivora are exam-
ined by almost precisely the same methods as are given
for the analysis of fodder (§ 129).

In the determination of woody fibre, owing to the pres-
ence of resinous matters it is often necessary to boil the
substance with alcohol before treating it with dilute acid
and alkali.

Microscopic examinations are often useful in the exami-
nation of these excrements, in order to ascertain what
parts of the plants, that were consumed as fodder, remain
undigested. For this purpose, it is well to knead a por-
tion of the substance in a linen bag under cold water un-
til the latter is no longer made turbid. Starch, crystals
of difficultly soluble salts, and grains of sand, may be
looked for in the sediment deposited from the water used
in washing, after long standing, while sugar, gums, lactic
acid, etc., may be sought for in the solution ; the residue
in the bag may be examined with the microscope, with or
without previous boiling with alcohol to remove resinous
matters.

224 § 115. FERTILIZERS.

n.

COMMERCIAL CONCENTRATED MANURES.

115. The determinations of phosphoric acid, potassa, and
-nitrogen, are the most important in the examination of
these manures.

a. The method first recommended by Pincus for esti-
mating phosphoric acid by means of a standard solution
of uranic acetate can be applied in the analysis of guanos,
bone-meal, bone-black, bone-ash, and most of the super-
phosphates, so long as but little ferric oxide or alumina is
present. The method deserves to be generally followed,
for it is quickly executed and sufficiently accurate, and
because it is desirable that all estimations of phosphoric
acid, in the numerous forms in which it is presented to the
public, should be made according to a common plan.

The preparation of the standard solution and the man-
ner of conducting the analysis have been already describ-
ed (§ 61, c).

For the determination, 50 c.c. of the solution to be test-
ed are generally taken, and 10 c.c. of the solution of sodic
acetate added. If the quantity of the precipitate that is
formed on the addition of this reagent and boiling is quite
small, it may be filtered out, washed, dried, and ignited ;
the residue may be regarded as ferric phosphate, FePO^,
containing 47.02°| „ of phosphoric acid (PoO J. The volu-
metric process is carried out Avith the filtrate from this
precipitate. If the precipitate of ferric phosphate is not
slight, a gravimetrical process is safer (§ 93, II).

The volumetric process, under suitable circumstances,
gives results that are within 1 mgr. of the trath.

§ 115. COMMERCIAL CONCEXTRATED MANURES. 225

In case a large quantity of phosphoric acid is present,
or much free acid, 10 c.c. of the acetate may not be suf-
ficient to saturate all this acid with soda. The brown
color will appear, then, before all the phosphoric acid is
precipitated; but it is diffused through the entire drop,
and does not present a well-defined brown zone where the
drop of the test solution and of the ferrocyanide come. to-
gether; in this case add 5 c.c. more of sodic acetate, and
it will be found that, in case free mineral acid was present,
more of- the uranic solution must be added before the
brown color appears. In order to be sure in regard to
this matter, it will always be well, after having reached
the point of saturation, to add 5 c.c. more of sodic acetate,
heat the mixture to boiling, and test a drop of the solu-
tion with the ferrocyanide. If a brown color appears, the
result first obtained was correct. Even 30 c.c. of sodic
acetate may be added without sensibly impairing the
accuracy of the work.

h. The examination for potassa may be conducted ac-
cording to either of the methods described in § 93, G.
The third method, in which platinic chloride is used to
separate potassa from the alkaline earths, is more particu-
larly applicable in the examination of the native potash
salts, of which such extensive beds have been discovered
in Germany, and from which large quantities are taken for
agricultural purposes.

c. The determination of the nitrogen is always made by
combustion with soda-lime (§ 85).

d. Fresenius {Quantitative Chemische Analyse^ 894)
gives the following good plan for stating the results of the
analysis of a superphosphate ; a similar plan can be fol-
lowed, with such variations as may be necessary in each
particular case, in stating the result of the analysis of any
commercial fertilizer.

10*

226

115. FERTILIZERS.

Eiisily
soluble

iu
Aviitcr.

Diffl-

cultly
soluble

ill
water.

Pliosphoric acid, H3PO4

Li"^« . 1 united
Ma<rncsia

ncsia

i FeiTic oxide f

[ Potassa J

r

Calcic sulphate
(CaS04, 2aq.)

I

with
the PoOs

Soluble
iu acids.

Phosphonc acid
Lime | united

Magnesia V with
[ Ferric oxide ) the acid
Insol.
in acids.
Volatile matter

nition

Water expelled at 100° C

Clay and saud

expelled on ig-

16.15:cont. P206[anhyd]
0.5

42.00

2.19
1.01

2.49

6.51
29.15
100.00

cont. PijOs [anhyd]

contain'^ nitrogen

P.O5

11.7

2.19

0.41
l37890:4i

N.

TARIFF OF PRICES OF COMMERCIAL FERTILIZERS.

c. In 1857, A. Stockhardt, of Tharand, published a
tariff of prices of commercial fertilizers, with the aid of
Avhicli, in a very simple manner, the cost of the mannre
could be compared with its real value ; in this tariff, the
estimation of the money value of each of the three im-
portant constituents of these fertilizers in general, was
b:ised upon the price that would have to be paid for it in
other and also commercial forms, containing a known and
often guaranteed proportion of tlie substance. The per
cent composition of a fertilizer being known, the j^ur-
chaser could then tell, on consulting the tariff, whether he
Avas required to pay any more for the number of pounds of
nitrogen or phosphoric acid in 100 pounds of the article
lie was buying, than he would have to pay for the same
number of pounds of nitrogen in the form of sulphate of
ammonia, from the gas-works, for example, or of phos-
phoric acid in tlie bone-black of the sugar refiners.

A greatly improved form of this tariff, which was put
out by Stockhardt in 1866 ( Chemische Ackersmcmn, 1866,

115.

TARIFF OF PRICES OF FERTILIZER-

227

226); is given below, with the prices estimated in gold^QT
pound.

Tlie editor greatly regrets that he has not had the time
or the opportunity to make a careful examination of the
various forms in which nitrogen, phosphoric acid, and pot-
ash, are to be had in this country, so that this tariif miglit
be conformed therewith, and answer the same purpose for
the American farmer that the original one does for the
farmers throughout Germany. But, nevertlieless, the
values allowed for these three substances in the tariff as
it stands are not far out of the way. Prof Johnson {Be-
port to the Secretary of the State Board of Agriculture,
0)1 Commercial Manures, April, 1869) gives the following
values ill gold: potash, 4 cents; soluble phosplioric acid,
12|- cents; insoluble, 4^ cents; nitrogen, IT cents. The
mean of the four values of nitrogen in Stockhardt's tariff
is 17.9 cents.

Prof. Johnson says very truly in the same report, " The
farmer will not often err in refusing to lay out his money
for any article whose cost much exceeds the calculated
value," with reference to his own tariff; and the same- may
as well be said of the scale of prices adopted in this work.

Form in which the substance exists in the fertilizer.

Phosplioric acid, soluble in water, as in superphosphate

" "in Peruvian guano ,

" " in steamed bones finely ground, in rape cake,

poudrette, etc

" " in Baker guano

" " in coarse l)one meal, fresh humanurine, etc..
" " in coarse broken bones, fresh human excre-
ments, stable manure, etc

Potash, as potassic sulijluite ,

" as potassic chloride and in other forms, ■. .

Nitrogen, easily soluble, or in compounds that are readily de-
comx)osed, as ammonia, nitrates, dried blood,

meat, urea, etc

" in finest bone meal, poudrette, etc

" in coarse bone meal, rape meal, horn meal, wool dust,

fresh human urine, etc

" in coarse broken bones, horn shavings, Avoolen rags,
fresh hura;ui excrements, stable manure, etc

Price
@lb.

in gold.

% .12^

.10

.083^
.07K
.07

.05K

My,

.05X

.23

.16X
.V6%

228 § 116. FEliTILIZEES.

Accordiug to this tariff, the money value of 100 pounds of the super-
phosphate whose composition is given above, would be estimated as
follows :

11.7 lbs. soluble phosphoric acid @ 12}^ cts. $1.46

2.19 " insoluble " " " 7>J " .32

.41 " nitrogen " ig)^ " .08

61.86

The value of a ton of 2000 pounds, at the same rate, would be $37.20
in gold.

BONE-MEAL.

116. Bone-meal, as found in commerce, is prepared
either from nearly or quite fresh bones, from bones that
have been exposed to the air for some time, or from those
that have been steamed or boiled ; the first kind contains
much fat and gelatine, and is usually quite coarse ; the
third kind has lost nearly all its fat and much of its gela-
tine, and is quite fine ; while the second occupies a position
between the other two in all respects.

a. Water. — ^Desiccate about 5 grms., if of the common
kinds of steamed bone-meal, at 100°.

h. IVon-TOlatilc matter. — Ignite the dried residue in a
and treat the ash with ammonic carbonate, to restore car-
bonic acid that was expelled by heat (§ 91, d),

c. Nitrogen. — Burn 0.5-0.8 grms. of the finely powder-
ed meal with soda-lime (§ 85).

cl Phosphoric acid. — Dissolve 3-4 grms. of the ash
obtained in h in as little nitric acid as possible, with the
aid of heat; filter the solution into a 250 c.c. flask, wash
the sandy insoluble residue, ignite, and weigh it. Fill the
flask with distilled water up to the 250 c.c. mark, mix its
contents well togetlier, and determine phosphoric acid in
50 c.c. of this solution, with the standard uranic solution
(§ 115, a). In order to saturate the free acid, it will be well
to add 20 c.c. of the sodic acetate. If a coarse, splintery

§ 116. I30XE-MEAL. 229

bone-meal is under examination, a larger quantity, about
50 grms., should be incinerated in order to get the ash for
treatment with acid.

e. Complete analysis of the ash. — Treat a portion of
the solution obtained in d according to Scheme IV., § 91,
taking 50-100 c.c. for a and the same for h. This exami-
nation is, in genera], unnecessary, if the only object of the
analysis is to determine the agricultural value of the
article.

f. Fat. — Exhaust a weighed quantity of the finely pul-
verized meal with ether, dry the residue at 125° C, and
count the loss as fat (§ 87).

g. Gelatine. — The gelatinous substances may be esti-
mated by the difference between the total loss on ignition
and the sum of the water and fat.

A. Fineness of division of the meal. — The value of
bone-meal depends not only upon its chemical composition,
but also upon the fineness of the powder.

To test the substance in this respect, it should be passed
through sieves of difierent degrees of fineness; and it is
important that all chemists should use sieves of the same
kind, so that the results obtained by different persons can
be compared with each other.

Wolff recommends the use of the three finest sieves of
the set made by Hugershoff, in Leipzig, the first of which

(I) has 1089 meshes in a square centimetre, the second

(II) 484 meshes, and the third (III) 256. The residue,
tliat will not pass through the coarsest sieve, should be
examined, in order to see whether it is made up largely
of grains which would pass through a little coarser sieve
still, or of large splinters.

One bone meal of excellent quality, analyzed by Wolff,
contained 60°!, of No. L, 20°|„ of No. II., and lO'l^of
No. III.

230 § 117. FERTILIZERS.

BONE-BLACK, BONE-ASH, PHOSPHORITE.

117. A. J3one-black, after it has been used by the sugar
refiners, usually comes into the market as a manure. Pul-
verize 30-40 grms. of it for examination.

a. Water. — Desiccate 3-4 grms. for a considerable time
at 150° C.

b. Non-volatile matter.— Ignite the dried substance
obtained in a, and treat the residue with ammonic car-
bonate, to restore carbonic acid expelled during the igni-
tion (§ 91).

c. Carbonic acid. — Estimate this in 3 grms. (§ 60).

cl Nitrogen.— Burn 0.5 to 0.8 grm. with soda-lime
(§ 85).

e. Phosphoric acid, etc. — Digest the contents of the
flask in c, after adding a little more nitric acid, several
hours on tlie water-bath ; filter the liquid into a 250 c.c.
flask, Mash the residue with hot water, dry it at 150°,
weigh, ignite, and weigh again. The loss on ignition gives
approximately the amount of charcoal, and the residue
left after icjnition is to be considered as scmd, thouirh it
may be tested with nitric acid to see whether any more
is soluble.

Dilute the contents of the flask to 250 c.c, mix all parts
of the solution well together, and determine phosphoric
acid in 50 c.c. with the uranic solution (§ 115, a).

/. Complete analysis of the ash.— Treat a portion of
the solution obtained in <?, or a solution obtained in the
same manner, as directed in Scheme IV., § 94, taking 100
c.c. for a and the same for b.

[/. Chlorine may be determined in a portion of the so-
lution obtained in e, by precipitation with argentic ni-
trate (§ 63).

h. Calcic hydrate. — It is sometimes desirable to de-
termine this in the bone-black. Moisten a portion of the

§ 117. BOXE-BLACK, BONE-ASH, PHOSPHORITE. 231

oriijinal substance witli a solution of ammonic carbonate.

evaporate the mixture very carefully to dryness in a cov-
ered crucible, repeat the operation several times, and ig-
nite, finally, to a dull red heat, not strong enough to burn
the coal. Determine carbonic acid in this residue ; the
diiference between the quantity found here and in c repre-
sents an equivalent quantity of calcic hydrate or caustic
lime, CaO, H^O.

B. Bone-ash should be treated as directed for the ash
of bone-meal, with tliB addition of determinations of
moisture and of carbonic acid, for the purpose of estimat-
ing the calcic carbonate.

C. Phosphorite^ coproUtes. — Phosphorite, nnd other
minerals containing phosphoric acid, are usually mixed
with oxides of iron and alumina to such an extent that
the acid cannot be determined volumetrically.

a. Phosphoric acid. — To determine this alone, Freseni-
us gives the following directions. {Fresenlus'^s Zeitschrift^
6, 404).

Heat about 0.5 grm. of the finely ptilverized minei'al in
a small flask about an hour on the water-bath, with 8-10
c.c. of concentrated (fuming) hydrochloric acid, and
evapornte the mixture to dryness in the usual manner for
eliminating silica (§ 58, «, 1 ) ; moisten the residue with 2
c.c. of hydrochloric acid, add, after a short time, 10 c.c.
of concentrated nitric acid (Sp. Gr. 1.2), dilute w4th
Avater, filter and wash the insoluble residue ; evaporate the
filtrate and washings almost to dryness, dissolve the resi-
due in 5 c.c. of nitric acid, transfer the solution to- a beak-
er, rinse out the evaporating disli with a little water, and
then wnth the solution of ammonic molybdate ; add, in
all, 150-200 c.c. of this reagent, and proceed with the
elimination of the acid as directed in § 61, h.

h. Complete analysis. — ^Digest 5-10 grms. of the well-
pulverized mineral with hydrochloric acid, filter out the

232 § 118. FERTILIZEllS.

insoluble substance, dry it, boil it repeatedly with sodic
carbonate, to dissolve out the silicic acid (§ 58, a, 2), and
treat this insoluble residue with 6-8 times its wefght of
sulphuric acid to decomj)ose the clay, as directed under
soil analysis (§ 102). Evaporate the solution in hydro-
chloric acid obtained above to dryness, and eliminate and
weigh the silica (§ 58, a, 1), and examine the filtrate from
the silica, as directed in Scheme I., except that manganese
need not be determined, unless a qualitative test reveals
its presence in notable quantity.

GUANO.

118i A. Peruvian cr other ammoniaoal guanos. —
Pulverize 200-500 grms. until the whole will pass through
a tolerably fine sieve.

a. Water. — Estimate this in 1-2 grms. in such a manner
as to collect tlie ammonia that is expelled at the same
time by the heat (§ 90, d). The amount of ammonia
given off is usually from 1-2" |^ of the weight of the guano.

h. Kon-VOlatilC matters. — Ignite 6-8 grms. carefully in
a platinum crucible (§ 91).

c. Nitrogen. — Burn 0.5 grm. with soda-lime. The mix-
ture should be made as quickly as possible in the tube,
and the bulbed tube attached immediately, to prevent any
loss of ammonia (§ 85, h).

d. Actual ammonia. — Determine this in 1 grm. by

Schlossing's process (§ 47, ^>).

e. Phosphoric acid, etc. — ^Digest the ash obtained in h
with nitric acid, filter out the sand^ wash, ignite, and
weigh it, and dilute the filtrate to 250 c.c.

Determine phosphoric acid in 50 c.c. of this filtrate, by
th3 volumetric method (§ 115, a).

For another method of estimating phosphoric acid alone,
mix 1 part of guano (1-2 grms.) with 1 part of sodic car-

§ 118. gua:j^o. 233

bonate and 1 of nitre, fuse the mixture carefully, dissolve
the residue in water, and evaporate the solution to dryness
on the water-bath ; treat this residue with hydrochloric acid
and water, as in eliminating silicic acid (§ 58, «, 1) ; filter,
add ammonia to the filtrate until it is in slight excess, then
acetic acid until the calcic phosphate precipitated by the
ammonia is dissolved ; and then, without filtering out the
small amount of ferric phosphate, determine phosphoric
acid by the volumetric method. (Fresenius.)

/ Complete analysis. — Treat a portion of the solution
obtained in c, or one obtained in like manner, after elimi-
nation of silicic acid, according to Scheme lY., § 94.

cj. Solubility in water. — Heat 10 grms. of the powdered
guano with 200 c.c. of water, filter at once through a
weighed filter, wash the contents of the filter with hot
water, as long as the water has any yellow color and
leaves a residue when evaporated ; dry and weigh the in-
colublo residue. Subtract the sum of the water and the
insoluble substance from the total wei2:ht of the miano,
and the remainder will be the soluble matter ; and, if the
insohible residue is ignited and the ash weighed and sub-
tracted from the total amount of ash, the amount of solu-
ble non-volatile matters will be given by the remainder.
(Fresenius.)

A. Uric acid. — Digest the part of the guano that is in-
soluble in water with a weak solution of soclic hydrate ;
filter the mixture, precipitate the uric acid in the filti-ate
with hydrochloric acid, and proceed as directed in § 75,
with the washing of the precipitate.

i. Oxalic acid, — Expel the carbonic acid from a weigh-
ed portion of the guano with sulphuric acid, neutralize
the excess of acid with sodic hydrate entirely free from
carbonic acid, and estimate oxalic acid with sulphuric acid
and manganic binoxide (§ 69).

h. Marks of a ^ood Peruvian guano.— It forms a loose,

234 8 119.

FERTILIZERS

yelloAvisli-browii powder mixed with soft lumps of various
sizes, which, when broken, exhibit white veins on the
fractured surface, or sometimes a foliated crystalline ap-
pearance.

If a small quantity is heated with a few drops of dilute
nitric acid and the mixture is evaporated to dryness at a
gentle heat, a fine, j^urple-red colored residue is left, indi-
cating the i:)resence of uric acid (§ 75).

It gives a good reaction for ammonia with sodic hydrate
or lime.

By digestion with water, about half is dissolved, form-
ing a dark-yellow solution; if the guano is poor, a hght-
yellow solution is obtained. This solution gives the usual
reactions for ammonia, lime, magnesia, and sulphuric acid.

It loses 60-70"! „ Avhen ignited, and leaves a grayish-
white ash that evolves but little carbonic acid when treat-
ed with nitric acid, and leaves but from 1-3° | „ of matters
insoluble in acid, and contains 5-10" |„ of fixed alkaline
salts.

Baker gucino^ and other phosphatk guanos. — These
arc examined in the same manner as the Peruvian guano,
except that, since they contain but a very small propor-
tion of nitrogen and alkaline salts, the determination of
phosphoric acid alone answers for the estimation of their
agricultural value. This may generally be made by the
volumetric process.

SUPERPHOSPHATES.

119. These are generally mixtures of calcic sulphate,
calcic chloride, tricalcic phosphate, ferric phospliate,
monocalcic phosphate, organic matters containing nitro-
gen,.coal and water.

Mix the sample well together, breaking up all the lumps
between the fingers or in the mortar.

a. Water. — Desiccate 3-4 grms. for a considerable time
at 150-160° C. (§ 90).

§ 119. SUPERPHOSPHATES. 235

h. Non-VOlatilc matters. — Ignite the dry residue ob-
tained in a (§ 91).

c- Nitrogen. — This should be determined, in case the
])hosphate was prepared from Peruvian guano or bone-
meal, or it is claimed that it contains nitrogenous matter.
Ignite 0.5-1 grm. with soda-lime.

d. Actual ammonia. — Determine this, if present, by
Schlossing's process, in 1-2 grms. (§ 47, h).

e. Phosphoric acid. — The value of a superphosphate
depends chiefly upon the amount of phosphate that it con-
tains that is soluble in water, and, when tiie article was
prepared from bone-black, bone-ash, phosphorite, or Baker
guano, the determination of soluble phosphate suffices for
the estimation of its value. But when made from steamed
bones, wholly or in part, there is commonly from 5-0" 1^ of
insoluble phosphate which should be taken into account.
It appears that sometimes the proportion of soluble phos-
phate diminishes when the article is kept for a long time ;
if, therefore, an unexpectedly small amount is found, a
determination of the insoluble phosphate should be made
also, in order to estimate fairly the value of the fertilizer.

1. To estimate the sohihle phosphate^ triturate 10 grms.
of the well-mixed sample with 200-300 c.c. of water, ap-
plying pressure enough with the pestle to break up the
lumps, but not to pulverize the hard grains ; let the mix-
ture stand some time, pour oif the clear supernatant liquid
through a filter, and repeat the exhaustion with water as
long as an acid reaction is communicated to a fresh por-
tion ; finally, put the whole insoluble residue on the filter,
dry it at 100"", and weigh it ; bring the volume of the
aqueous extract to 1000 c.c.

Determine phosphoric acid by the volumetric method
in 100 c.c. of this solution, first precipitating and filtering
out the fetric phosphate, if but a small quantity is formed,
and dry and w'eigh this precipitate ; 47.02" |„ of it is phos-

236 § 119. FERTILIZERS.

phoiic acid. If the superphosphate was made from a
phosphatic guano, this precipitate of ferric phosphate will
generally be too large to allow an accurate volumetric
estimation of phosphoric acid, and a gravimetrical method
should be followed. (§ 93, Jl)

2. To estimate the insoluble phosphate, treat 20 grms.
of the substance with water to which 20 c.c. of nitric acid
(Sp. Gr. = 1.4) have been added, and digest the mixture
several hours on the water-bath. If a sufficient quantity
of acid was added, the insoluble residue left after diges-
tion can be plainly seen, when stirred up, to consist of
nothing but heavy sand and particles of coal; if the so-
lution appears to be incomplete, add 10 c.c. more of the
acid and heat the mixtuie again several hours ; finally,
filter the solution into a litre flask, and when the filtrate
is cool, bring its volume up to 1000 c.c. ; determine phos-
phoric acid by the volumetric method (§ 115, a) in 50 c.c.
of this solution, using 20 c.c. of sodic acetate.

This result gives the total amount of phosphoric acid
in the superphosphate, and, as the soluble phosphate has
already been determined, the amount of insoluble phos-
phate is readily estimated.

The insoluble residue of sand in this examination may
le ignited and weighed.

f. Complete analysis* — Examine the aqueous solution
prepared above, if it is particularly desired to learn its
composition, according to Scheme IV., § 94, taking 100 c.c.
for (7, and 100 c.c. for h with previous treatment with
sodic carbonate and potassic nitrate ; also determine chlo-
rine in 50 c.c. of the solution, by precipitation with ar-
gentic nitrate (§ 63).

Or, for a more complete analysis, including the determi-
nation of what is soluble in acid with what is soluble in
water, examine the nitric-acid solution obtained in e ac-
cording to Scheme IV., except in case the phosphate
contains much organic matter, when it would be better to

§ 120. GYPSUM. 237

analyze a solution of the ash obtained in ^, in nitric acid.
^f(/2Jhuric acid and chlorine, however, must always be
determined in the nitric-acid solution of the original sub-
stance.

GYPSUM.

120. a. Water. — Ignite 2 grms. of the finely pulverized
gypsum gently.

b. Insoluble matters. — Digest 2 grms., likewise finely
powdered, witli very dilute hydrochloric acid, as long as
anything appears to be dissolved, filter out the insoluble
sand and clay, wash well with hot water, dry, ignite, and
weigli the insoluble residue.

c. Sulphuric acid, ferric oxide, lime, etc—Divide
the acid solution in two equal parts, and in one pre-
cipitate sulphuric acid with baric chloride (§ 59), and
in the other, after dilution with water and heating with
a little concentrated nitric acid, precipitate ferric oxide
and alumina, with ammonia in slightest possible excess
(§ 51). Filter the precipitate out quickly, so as to
avoid the precipitation of calcic sulphate in the alkaline
solution, wash it Avell, and then weigh it after ignition.
Immediately on filtering out this i^recii^itate by ammonia,
add ammonic oxalate in excess to the filtrate to pre-
cipitate the lime (§ 49, a), and estimate magnesia in tlie
filtrate from the lime, in the usual way with hydric
disodic phosphate (§ 50, b)

d. If there is a considerable precipitation of ferric oxide
by ammonia, some calcic sulphate is very liable to be
mixed with it. In this case, it is better to boil about
1.5 grms. of the finely powdered gypsum an hour with a
solution of 6-8 grms. of pure sodic carbonate ; by this
operation, if the gypsum was properly pulverized, it is
completely converted into calcic carbonate. Filter, wash
the contents of the filter well with liot water, and precipi-

238 § 121. FEKTILIZEES.

tate the sulphuric acid in the filtrate with baric chloride ;
transfer the filter with its contents to a deep beaker, and
dissolve the carbonate in dilute hydrochloric acid with
the usual precautions, filter, wash well, dry, ignite, and
weigh the i-esidue of sand and clay. Determine lime and
magnesia in the filtrate in the usual manner (§ 50, b).

e. Alkalies* — To determine these in gypsum, boil 10
grms. repeatedly with dilute hydrochloric acid, filter, and
eliminate the alkalies as chlorides (§ 93, G.).

f. A determination of ccirbotuG acid will furnish means
of estimating the amount of calcic carbonate in the gyp-
sum ; take 5-10 grms. for the analysis (§ 60).

SALT. POTASH COMPOUNDS.

121. A. Salt. a. Water. — Gently ignite 3-4 grms.,
well pulverized, in a platinum crucible that is kept well
covered, and carry the temperature finally to a dull red.

b. Complete analysis. — Dissolve 10 grms. in hot water,
filter the solution into a litre flask, and wash, dry, ignite,
and weigh the insoluble residue.

This residue consists mostly of sand and clay. If gyp-
sum is contained in it, digest it with dilute hydrochloric
acid as long as anything appears to be dissolved, filter
the solution, add ammonia in excess to the filtrate, filter
out the precipitated ferric oxide and alumina, precipitate
lime in the filtrate by ammonic oxalate, and sulphuric acid
in the filtrate from the calcic oxalate by baric chloride
after acidification with hydrochloric acid.

Bring the volume of the aqueous solution of the salt, ob-
tained above, to 1000 c.c, and determine lime and mag-
nesia in 400 c.c. (§ 50, b), and chlorine in another portion
by the volumetric process (§ G3, b). Dilute 300 c.c. with
more water, acidify it with hydrochloric acid, and exam-
ine the solution for sulphuric acid and the alkalies (§ 93,

§ 122. CHILI SALTPETRE. 239

E and G). The determination of potassa in common
salt is generally unnecessary.

B. Potassa salts. — Dissolve 10 grms. in hot water, and
determine joo^«ss« at once with platinic chloride in a por-
tion of the solution (§ 93, G, 3).

For the complete analysis, or the determination of
water, proceed as directed for the analysis of salt.

CHILI SALTPETRE.

122. a. Water.— Desiccate 3 grms. at 110° C.

b. Complete analysis. — Treat 20 grms. of the pulver-
ized salt with hot water, filter the solution into a litre
flask, collect the insoluble residue on a dried and weighed
filter, wash it well with hot water, dry it at 125° C,
weigh it, and then ignite it at a low temperature, and
weigh the ash. These results give the amount of insoln-
hle sand and clay, and, approximately, the organic tnatter.

Bring the volume of the aqueous solution to 1000 c.c,
determine sulphuric acid and chlorine in two portions of
200 c.c. each, by precipitation with baric chloride (§ 59)
and argentic nitrate (§ 63), and lime and magnesia in an-
other portion of 500 c.c. (§ 50, V),

c. Soda. — This may be estimated by the difierence
between the total amount of substance taken, and the
sum of the acids, water, organic matter, and the other
bases ; or it may be estimated by converting all the bases
into sulphates, in the manner described for converting
potassa into sul|)hatc (§ 44), and weighing the mixture
of the salts ; then subtract from this the sum of the
weights of calcic and magnesic sulpliate, as estimated from
tlie determination of those bases, already made, and the
remainder will be the sodic (and potassic) sulphate.

d. To determine approximately the amount of potassa^
if any is present, dissolve this residue of mixed sulphates

240 § 122. FERTILIZERS.

ill very dilute hydrochloric acid, determine sulphuric acid
in the solution by precipitation with baric chloride (§ 59),
deduct so much of the sulpbuiic acid as is estimated to
have been combined with the lime and magnesia, and de-
duct also the corresponding quantity of sulphates from
the total amount of sulpliates, and with these remainders
estimate the potassa and soda by the formula for the in-
direct determination of these bases (§ 48, e).

e. Nitric acid. — This may be determined by Schluss-
ing's process in 10-20 c.c. of the aqueous solution ob-
tained in b, or by fusion of about 2 grms. of the salt with
silicic acid (§ 62). This estimation can be dispensed
with, since the weight of the nitrates equals the difference
between the. total amount of salt taken, and the sum of
the sulphates and chlorides, as already determined.

f. If the Chili saltpetre is adulterated with salt, its so-
lution will give an abundant precipitate with argentic
nitrate ; if adulterated with soda (sodic carbonate) it will
2:ive the reaction for carbonic acid ; if with magnesic sul-
phate (Epsom salts), it will give a decided reaction for
sulphuric acid and for magnesia ; and if with sodic sul-
phate (Glauber's salt), it will give a decided reaction for
sulphuric acid, but none for magnesia.

§ 123. ASHES OF PLANTS. 241

CHAPTER YII.

ANALYSIS OF ASHES.

I.

ASHES OF PLANTS.

123. To prepare the plant for incineration, it must first
be most carefully cleaned ; and too much care cannot be
taken in this respect, for if any particles of sand or clay
are left adhering to the object, the accuracy of the analy-
sis is of course thereby greatly impaired, or the analysis
itself is rendered much more difficult of execution.

a. Roots and tubers must be cleaned with a soft brush,
under a current of water, and be afterwards repeatedly
rinsed off with distilled water, and immediately dried
with a soft cloth. The dust is removed from stems and
leaves, when possible, by wiping them with a soft cloth.
/Seeds, particularly the larger kinds, may be put in dis-
tilled water for a few minutes, and immediately, before
the water can have time to penetrate them, put on a
sieve to drain, laid on filter paper and dried as quickly
as possible between soft cloths.

b. To dry the green parts of plants and fleshy roots,
hang them on threads in a drying-chamber, the roots
being cut in thin slices. Tubers may be dried in the same
way. Koots and tubers so dried are then coarsely pul-
verized in the mortar, while leaves and stems are cut up
with clean shears ; seeds are broken up to a coarse powder
in a mortar.

c. The incineration is best efiected in shallow platinum
trays, that are heated over the gas-lamp, or in large cast-
iron muffles, about 50 cm. long and 13 cm. wide, bujlt

11

242 § 123. ANALYSIS OF ASHES.

into an appropriate furnace in such a manner as to be
heated mostly at the sides and on the top. The heat
must, at first, be kept very low for several hours, or even
days, while the substance is slowly charred ; the coal,
when so slowly formed, takes a more porous consistency.
When the evolution of gases has nearly ceased, the heat
may be gradually raised, but not at any time to a percep-
tible red ; in this way, at least in the incineration of most
of the fodder-plants, roots, and woods, that yield an ash
rich in carbonates, a perfect combustion is obtained with-
out fusing the ash. In case some coal remains, that re-
sists combustion without applying too high a heat, exhaust
it with hot water two or three times ; the washed residue
is usually very easily burned. Then either add the aque-
ous solution just obtained to the ash, evaporate the mix-
ture to dryness on the water-bath, ignite the residue very
gently, and weigh it ; or weigh the last ash, and bring
the aqueous extract of the coal to a certain volume, and
for each part of the subsequent analysis, mix together
equal fractional parts of ash and extract.

Substances rich in silica, as the grasses, and the stems
and chaff of cereals, and also seeds rich in alkaline phos-
phates, are with difficulty made to yield an ash that is free
from coal. Such substances should first be charred at a
very low temperature ; then, without disturbing the coal
in tlie dish, moisten it with a cold saturated solution of
baric hydrate, dry the moistened mass, and ignite it in the
mufile at a barely visible red heat ; the completion of the
incineration generally requires from 8 to 12 hours. Enough
baryta water must be added, by moistening and drying
the coal several times, so that the ash will contain about
half its weight of baryta. The addition of this substance
almost entirely prevents the escape of the chlorine, effects
a more speedy combustion of the coal, makes the silicates
decomposable by acids, and insures the presence of phos-
phoric acid in the ash in a readily determinable form.

§ 124. ASH RICH IX CARBONATES, POOR IX SILICA. 243

The whole quantity of the ash, in whatever way ob-
tained, should be most carefully pulverized and mixed
together before any sample is taken for analysis.

A. ASH RICH IN CARBONATES, AND POOR IN SILICA.

124. a. Carbonic acid. — Determine this in 1-2 grms.,
using nitric acid to expel the carbonic acid.

h. Chlorine. — Estimate this in the nitric-acid solution
obtained in a, after filtering out the insoluble portion.

c. Silica, sand, and coal. — Moisten a portion (3-4 grms.)
in a flask, with concentrated nitric acid, add concentrated
hydrochloric acid, and digest the mixture for a long time
at an almost boiling heat. Rinse the whole into an evapo-
rating ciish, evaporate to dryness, moisten the residue with
hydrochloric acid, and proceed to eliminate and deter-
mine silica, sand, and coal, as directed in § 58, «, 3.

If the ash contains no sandy particles, as may be shown
by the absence of any grittiness when the residue, insolu-
ble in hydrochloric acid, is stirred with the glass rod, the
boiling with sodic carbonate may be omitted, and nothing
need be done but collect the silica on a weighed filter, dry
it at 110°, weigh it, and ignite, and weigh it again, to
determine the un consumed carbon that may be mixed
with it.

If there are more than a few centigrammes of this carbon
in three or four grammes of the ash, the substance has not
been properly incinerated, and very unreliable results
may be obtained in the analysis, particularly as regards
the phosphates and the alkalies.

d. Complete analysis. — Bring the filtrate from the in-
soluble portion to a volume of 500 c.c, and examine it
according to Scheme IV., § 94. If more than traces of
manganic oxide are present, and it is desired to estimate
this base, proceed according to Scheme III., § 94.

244 § 124. ANALYSIS OF ASHES.

B. ASH RICH IN SILICA, MIXED WITH BARYTA.

a. Determine carbonic acid and clilorine, and pre-
pare the solution for the complete analysis, precisely as
under A.

The residue, insoluble in hydrochloric acid, on eliminat-
ing silica in the usual way, contains, besides sand and
unconsumed carbon, baric sulphate, in which is the sul;
phuric acid of the ash, and it must be treated accord-
ingly. Collect it on a dried and weighed filter, wash it,
dry it at 110° C, and weigh. Then treat it with sodio
carbonate (§ 58, a, 2) ; but, as the baric sulphate is not
readily decomposed by the carbonated alkali, the boiling
must be repeated several times, with fresh portions of the
carbonate, the insoluble part allowed to settle completely
after each boiling, and the clear liquid decanted without
transferring any notable quantity of the solid to the filter ;
when the filtered liquid gives no reaction for sulphuric
acid, after acidification with hydrochloric acid, the decom-
position may be considered as ended ; if the portion with
which the test is made gives a reaction with baric chlo-
ride, it should be put back into the liquid to be boiled.

Transfer the silica and coal to the filter, after the boil-
ing is finished, pour dilute hydrochloric acid over it as
long as there is any effervescence, wash the filter care-
fully with water, dry at 110°, weigh, ignite, and weigh
again, and so estimate sand and unconsumed carbon, as
under A.

Evaporate the alkaline solutions and washings to dry-
ness, and eliminate silica (§ 58), and determine sulphuric
acid in the filtrate from the silica, with the aid of baric
chloride (§ 59).

b. Complete analysis* — Examine the solution obtained
in a, and filtered from the silica, etc., according to Scheme

§ 124. MISCELLANEOUS DETERMINATIONS. 245

III. or lY., § 94, with these exceptions, that sulphuric acid
need not be determined under a, and that, before precipi-
tating lime by ammonic oxalate, the barium should be
removed by precipitation with a very dilute sulphuric
acid, containing but one part of acid in 300-400 of water ;
the precipitated baric sulphate should be examined for
lime by heating the moist precipitate with ammonic car-
bonate, washing it, and then treating it with dilute hydro-
chloric acid, neutralizing the acid with ammonia, and
adding ammonic oxalate.

C. MISCELLANEOUS DETERMINATIONS.

a. Sulphur. — A part of this is volatilized during the
process of incineration. In order, therefore, to determine
the total amount in the plant, treat 4-5 grms. of the dry
substance with fused potassic hydrate and nitrate (§ 92).

b. Sulphuric acid, already formed in the plant. — A

few cultivated plants contain more than mere traces of
this acid. To determine it, and also the chlorine^ if it is
desired, prepare an extract of the plant by water contain-
ing ^ I20 of nitric acid.

Draw out one end of a glass tube, about 60 cm. long
and 1-1' I2 cm. in diameter, in such a manner that a rubber
tube and clamp can be attached, after the fashion of a
Mohr's burette. Close the throat of the tube, where it
begins to taper into the smaller tube, with a plug of cot-
ton that has been previously boiled in the acidulated
water, such as is to be used for the extraction. Put 8-10
grms. of the dried substance in the tube, fill the latter
with the acidified water, and let the two remain in contact
several hours ; then open the clamp, let some of the water
run off, add fresh acidified water, and repeat the operation
until the extract gives at the most the merest opalescence
with argentic nitrate.

246 § 125. ANALYSIS OF ASHES.

In this acid solution precipitate sulphuric acid with baric
acetate, and chlorine with argentic nitrate in the filtrate
from the baric sulphate ; treat this last precipitate as one
produced in the presence of organic matter, if it is at all
abundant.

125. The following method of incineration and analysis
is given by Reichhardt, by which the volatilization of any
mineral matters is avoided, as well as the addition of any-
thing to the ash to facilitate incineration.

1. Carefully char enough of the dried substance to yield
2 grms. of ash, pulverize the coal, and exhaust it with
several portions of hot water.

a. Add argentic nitrate to this extract immediately.

h. Exhaust the coal with w^ater containing a little nitric
acid, wash with the same, and add this extract to a.

2. Incinerate the coal completely, and exhaust the ash,
first with water, and then with moderately concentrated
nitric acid, and add these extracts to those obtained in 1.

3. Determination of sulphur and chlorine. — The pre-
cipitate by argentic nitrate, in these extracts, contains the
sulphur that was present in a soluble form in the plant,
and the chlorine. Acidify the mixture of precipitate and
liquid with nitric acid, if not already acid, collect the
precipitate of argentic sulphide and chloride on a dried and
weighed filter, wash it well, and add the filtrate and wash-
ings to those obtained in 4, below.'

Treat the precipitate on the filter with ammonia, by
w^hich the argentic chloride is dissolved, wash the insolu-
ble argentic sulphide, dry it at 100°, and weigh. It con-
tains 12. 9° 1 0 of sulphur.

Precipitate argentic chloride in the ammonio extract, by
nitric acid in excess, and treat the precipitate in the usual
manner (§ 63).

4. Heat the residue, insoluble in nitric acid in 2, with

§ 126. MISCELLANEOUS DETERMINATIONS. 247

concentrated hydrochloric acid, and filter. By mixing this
filtrate with that obtained in 3, the excess of silver is pre-
cipitated, and may be removed from the solution by fil-
tration.

«

5. Treat the residue, insoluble in hydrochloric acid, as
directed in § 58, a, 3, for the separation of silica, sand,
and coal.

6, Eliminate the silica in the hydrochloric solution fil-
tered from the excess of silver in 4, in the usual manner
(§ 58, a, 1), and examine the filtrate from the silica ac-
cording to Scheme III. or lY., § 94, according to whether
manganese is or is not to be determined.

126. Statement of results. — So much sodium as is nec-
essary .to combine with all the chlorine should be consid-
ered as so combined, while the remainder of the sodium is
given as sodic oxide.

If there is not sodium enough for this purpose, take
enough of the potassium to combine with what chlorine
is left, and give the remainder of the potassium as potassic
oxide.

The manganese is to be given as manganous manganic
oxide, Mn3 0,.

The sand and coal are accidental ingredients of the ash,
and therefore the percentage composition should be calcu-
lated with reference to what is left after subtracting these
from the weight of ash taken for analysis.

The percentage composition should moreover be given
with reference to the remainder left after subtracting the
carbonic acid also, since this is not properly one of the
mineral substances found in the plant, but results from the
combustion of the organic acids.

The first statement enables one to judge of the accuracy
of the analysis, and the second gives the real composition
of the mineral matter found in the particular plant exam-
ined.

248

121

ANALYSIS OF ASHES.

Analysis of the ash of hops. (Wheeler.)

Potassa ,

Soda

Lime

Magnesia ,

Ferric oxide

Manganous manganic oxide

Alumina ,

Pliosphoric acid

Sulpburic acid

Potassic cliloride

Sodic chloride

Silicic acid ,

Carbonic acid

Charcoal and sand

Total ash

CO2, coal,

etc.,

CO2, etc.,

included.

deducted.

37.79

44.33

11.36

13.33

1.27

1.49

0.48

0.56

trace.

trace.

12.67

14.86

1.98

2.32

8.48

9.94

1.21

1.41

10.03

11.76

12.50

1.91

99.67

100.00

9.14

II.

THE ASH OF ANIMAL SUBSTANCES.

127 1 Animal substances are incinerated with difficulty,
particularly when they fuse before they become charred;
the attempt should be made, however, to burn them with-
out the addition of any agents.

First char the dry substance in a platinum dish, raising
the heat very slowly, so as to avoid fusion, if possible ;
when the charring has attained such a point that water is
no longer colored when left for a time in contact with the
coal, break the coal up into a coarse powder, and boil and
wash it several times with water, acidified with a little
nitric acid in case no carbonates are present, or carbonic
acid is not to be determined ; then dry tlie coaly residue
and complete the incineration in the muffle, at a barely
visible red heat.

Sometimes it will be found necessary to repeat the
exhaustion with water and heating in tlie muffle several
times, before the incineration can be completed.

§ 128. ASHES OF FTTEL. 249

This process, will, however, hardly succeed in many
cases, and usually only when the ash yielded by the sub-
stance is rich in alkaline carbonates or sodic chloride, or
when but a small quantity of the substance is incinerated
in order to determine the total amount of ash. Since a
considerable proportion of alkaline phosphates is often
present, which is converted into pyrophosphate during
the incineration, it is generally necessary to treat the
charred substance ^^•ith baryta water, in the manner di-
rected for the incineration of vegetable substances rich in
phosphates.

In the analysis of the ash, proceed as directed for the
analysis of ashes of plants, with the exception that, since
silicic acid and sand are rarely present, the work is some-
what simplified. The total sul])hur should be determined
in a portion of the substance that has been heated with
potassic hydrate and nitrate (§ 92).

III.

ASHES OF FUEL.

128. a. Carbonic Acid. — Determine this in 2 grms.
h. Chlorine* — Determine this in the nitric-acid solution
obtained in a.

c. Complete Analysis. — Conduct this as directed for the
analysis of the ash of plants poor in silica. (§ 124, c, d.)
The estimation of potassa and phosj^horic acid is of most
importance in respect to the agricultural value of the
ashes. 10-15 grms. of wood ashes, or 15-25 gnns. of
peat or coal ashes, should be treated with acid, in order to
prepare a sufficient quantity of the solution.

d. Potassa. — For a volumetric determination of potassa
that will answer very well for practical purposes, treat
6.91 grms. of the wood ashes in a flask of about 300 c.c.
capacity with 5-6 grms. of caustic lime and 40-60 c.c. of

11*

250 § 128. ANALYSTS OF ASHES.

water, and heat the mixture to boiling. Filter the solu-
tion into a graduated cylinder, and wash the insoluble
residue with sufficient water to make the volume of the
solution exactly 100 c.c, when properly cooled. Titrate
10 c.c. of this solution with the normal acid (§ 44,/*),
subtract 0.3 c.c. for the excess of lime, and then multiply
the number of cubic centimetres required by 10, for the
per cent of potassic carbonate.

Peat and Coal Ashes are usually very poor in alkalies
and phosphoric acid. Their agricultural value depends
more particularly on. the amount of calcic sulphate
(gypsum), and calcic carbonate and phosphate, which they
contain.

Many kinds of peat leave ashes that are rich in gypsum ;
in such cases it is well to boil about 2 grms. of the ashes
an hour, with a solution of 6-8 grms. of sodic carbonate,
and determine sulphuric acid in the aqueous solution so
obtained, and lime in the hydrochloric solution of the
residue insoluble in water.

§ 129. FODDER. 251

CHAPTER VIII.

FODDER AND FOOD.

I

FODDER.

129. In the examination of fodder, it is very desirable
that chemists should follow a common method.

The processes of analysis that have been perfected at
the experimental station, Weende, by Henneberg, Stoh-
mann, Rautenberg, Kiihn, Aronstein, and Schulze, com-
mend themselves for general use.

a. Preparation of the Sample for Analysis.— In order
that the sample may fairly represent a large quantity of
the fodder, a handful should be taken here and there from
all parts of the pile or the field, till 15-20 such portions
are obtained: mix the whole well together, and take
about 1 kilo, of dry fodder or 3-4 kilos, of green for the
sample.

Cut it up with shears, weigh it, dry it for several days
in a drying-chamber at 50-60°, expose it to the air 24
hours, and weigh it again in this air-dried condition.

b. Hygroscopic Water, — Grind 50 to 100 grms. of the
dry substance quickly in a steel mill and desiccate 10 grms.
of this powder at 110° C.

c. IVon-TOlatile Matter. — Incinerate the dried sub-
stance obtained in b, subtract carbonic acid and coal, and
calculate the non-volatile matter in the fodder as it was
taken for analysis,

130. Reduce the rest of the air-dried substance to a
fine powder, by alternate grinding and sifting, and pre-
serve it in well-stoppered bottles.

a. Water. — Desiccate 3-5 grms. of this powder at

252 § 130. FODDER AND FOOD.

110° C.,and calculate the amount of dry substance in the
powder.

h. Protein Compounds. — ^Ignite 0.7 to 1 grm. with
soda-lime (§ 85).

c. Fatty Substances. — Extract these from 6-8 grms.,
by ether (§ 87).

d. Crude Cellulose.— Boil a quantity of the powder
containing about 3 grms. of dry substance, half an hour,
with 200 c.c. of dilute sulphuric acid, containing 1.25° |„
of monohydrated acid, in a flask that is attached to the
lower end of a Liebig's condenser; let the mixture stand
till the solid particles settle to the bottom ; draw the clear
liquid off into a beaker, as completely as possible, with a
small siphon, and finally with a pipette ; pour 200 c.c.
of water over the residue in the flask, boil again half an
hour in the same manner as before, and as before let the
solid particles settle and remove the clear liquid ; repeat
this operation once more.

Then boil the substance in the same way with 150 c.c.
of water and 50 c.c. of a solution containing 50 grms. of
fused caustic potash in the litre, and afterwards twice with
200 c.c. of water, removing the liquid each time in the
same manner as described for the sulphuric acid, but put-
ting these alkaline washings in a beaker bj^ themselves ;
finally, bring the residue on a dried and weighed filter.
Then, with the siphon, draw off" the clear alkaline liquid
from any sediment that may have been deposited in it ;
transfer this sediment to the same filter, and wash the
whole, as long as the Avashings have an alkaline reaction ;
then add the sediment in the beaker containing the acid
washings, after drawing ofi* the clear liquid with the
siphon, and wash again, as long as the washings have an
acid reaction. Wash the contents of the filter succes-
sively with alcohol and ether ; dry the filter and its con-
tents at 110°, weigh, incinerate the residue, and weigh

§ 131. FODDER. 253

the ash. The difference between the total weight of the
insoluble residue and that of the ash equals the crude
cellulose or fibre.

The residue obtained in this way is a mixture of cellu-
lose with various other substances. When obtained from
the grasses it is comparatively the purest, but contains
2-3"! g of protein compounds. When prepared from clover,
it contains 5-6" \^ of the same substances ; but even after
subtraction of these albuminoids, the residue contains
1-7° lo more carbon than pure cellulose.

131. a. Dry Matter Soluble in Water.— To determine
the amount of substance soluble in water, boil 10-20
grms. with 10-12 successive portions of 200-300 c.c. of
water in a flask that is connected with the lower end of a
Liebig's condenser (§ 39, <?), and after each boiling, sepa-
rate the water as quickly as possible from the residue ; all
the portions of w^ater are afterwards passed through a
ribbed filter, that is j)ierced with the glass rod and
replaced by a new one as often as it becomes choked up,
so that the filtration shall proceed as rapidly as possible.
Bunsen's method of filtration can be used in this case to
great advantage.

The extraction should, at any rate, be finished in one
day, so that the solution may not begin to mould before
it is examined.

Evaporate 200 c.c. of the extract almost to dryness, in
a platinum dish, on the water-bath ; complete the desic-
cation on hot sand, under the receiver of the air-pump
(§ 90), and weigh the residue.

b. IVon-Tolatile Matter Soluble in Water.— Incinerate
the residue obtained in a. Generally an ash free from
coal can be obtained ; if not, filter out and weigh the
coal in the usual manner, and subtract it and the carbonic
acid from the total residue.

An excess of mineral matters is always found in this

254 § 131. FODDER AND FOOD.

solution, for the water dissolves some of the glass with
which it comes in contact.

If it is not desired to subject the residue insoluble in
water to further treatment with alcohol and ether, as
below, it can be dried and weighed, and ash and nitrogen
determinations made with portions of it ; then, by sub-
tracting the amount of ash and nitrogen found in it from
what was found in the original substance, the amount that
should be found in the aqueous extract may be estimated,
and thus the tedious evaporation of a portion of that '
extract to dryness be avoided; or the two sets of deter-
minations may be made to control each other ; the differ-
ence between the amount of substance taken for extraction
with water and the weight of the insoluble substance,
above determined, will give the amount soluble in water.

Or, since the alcohol and ether used for extracting the
residue insoluble in water, as below, usually take up but
traces of mineral matters, we can, in case these solvents
take but a few per cent of that residue into solution,
consider the residue insoluble in alcohol and ether as con-
taining the same amount of ash ingredients as the residue
insoluble in water only, and the determination of the
ash in this will answer the same purpose as if estimated
in the first insoluble residue.

c. Nitrogen in Forms Soluble in Water.— Evaporate
500-1000 c.c. of the aqueous extract to a syrup, on the
water-bath, absorb the residue by as small a quantity of
calcined gypsum as possible, collect the whole in a watch-
glass, dry it for a while at 88-90° C, and ignite the residue
with soda-lime (§ 85, a).

d. Actual Ammonia. — Detennine this in a portion of
the aqueous extract, by Schlossing's method. Acidify
300 c.c. of the extract with hydrochloric acid, and con-
centrate it. A more accurate result may be obtained by
Knop's method of setting free the nitrogen and measuring

§ 131. FODDEK. 255

its volume in the azotometer. [See Fresenius's Quan-
titative A^ialysis.)

e. Sugar and Gum in Aqueous Extract.— Evaporate
500 to 1000 c.c. nearly to dryness, as quickly as it can be
done without loss, and, if j^ossible, in a space where the
air can be rarefied, and exhaust the moist residue with
alcohol of 80-85" Iq, by repeated boiling with fresh por-
tions of the solvent, as long as it is colored. Filter the
liquid, add water to the filtrate, expel the alcohol by heat,
filter through animal charcoal, if necessary, bring this
filtrate to a certain volume, and estimate glucose and
saccharose (§ 81).

Dry the residue insoluble in alcohol at 100° C, weigh,
and incinerate it. Subtract the ash and protein com-
pounds, as may be estimated from determinations already
made, from the total amount of the residue insoluble in
alcohol, and call the remainder gum and vegetable acids.

f. Nitric Acid. — To control the determination of nitro-
gen already made in a portion of the aqueous extract,
nitric acid maybe determined, in addition to the ammonia
already estimated; thus it may be leanied how much
of the nitrogen is present in the form of these inorganic
substances.

Evaporate 500-1000 c.c. of the aqueous extract to a
small bulk, and determine nitric acid by Schlossing's
method (§ 62, a).

Friihling and Grouven {LandwirthscK Versuchs-zSta-
tionen, 9, 9) prepare the aqueous extract of the plant,
particularly for the determination of nitric acid, as fol-
lows : Put 100-500 grms. of the finely divided but not
ground air-dried substance in strong beakers of a capacity
of two litres; add enough 50" |q alcohol, so that the whole
mass of the solid will be completely covered, when pressed
down firmly with a pestle and kept down by a plate
w^eighted with a glass filled with mercury.

266 § 132. FODDEK AND FOOD.

After 12 hours, pour off the dark-colored liquid, wrap
the solid mass in a linen bag, and, with a powerful screw-
press, force out the remainder of the alcohol. Pour
diluted alcohol over the press-cake 4 or 5 times, and each
time press the liquid out completely. In this way 1-2
litres of a highly-colored alcoholic extract are obtained.
Heat the liquid almost to boiling till all the alcohol is
volatilized, evaporate it to a small bulk, add an excess of
rather thick milk of lime, and boil the mixture for some
time ; allow the precipitate to subside, draw off the clear
liquid with a siphon, filter the remainder through linen,
and wash the residue well ; heat the solution thus ob-
tained, pass carbonic acid through it, boil and filter;
evaporate the filtrate to a small bulk, and use the whole
of it for the determination of nitric acid by Schlossing's
process (§ 62, a), in case there is reason to believe that but
little is present ; or a part of it may be used for this pur-
pose, and the remainder treated as directed above for the
examination of the aqueous extract.

132. If it is desired to estimate still more in detail the
no7i-nitroge7ious substances in the fodder, boil the residue
that is insoluble in water (§ 131, a), first with common,
and then with absolute alcohol, so long as the washings
are colored ; then extract this second residue with ether ;
these extractions can be most conveniently made with the
aid of the washing-bottle filtering arrangement (§ 39, c).

a. Evaporate both the extracts, or aliquot parts of
them, to dryness, to determine the amounts taken into
solution.

h. Crude Cellulose.— Treat 2-4 grms. of the residue
that has been exhausted with alcohol and ether above, as
directed in § 78.

In case solid excrements are being analyzed to deter-
mine the amount of cellulose in them as compared with
fodder, a longer maceration is advisable, for 14-16 days,
instead of 12-14.

§ 133. BEETS, TURNIPS.

257

c. starch. — ^Wash 2 grms. of the powdered substance
on a filter, with cold water, and then, if much gluten is
joresent, wash with alcohol containing sulphuric acid, and
finally with water. Treat the residue with dilute sul-
phuric acid or malt, to convert the starch into glucose,
and estimate the glucose with the standard cupric solution

(§ 81).

The difference between the sum of the weights of the
cellulose, protein compounds, and mineral ingredients in
the dried substance, and the weight of the substance
insoluble in water, alcohol, and ether, gives the amount of
difficultly soluble non-nitrogenous matters, of which starch
will form a considerable part.

Analysis of the Pea. (Yoelcker.)

Pen. Pod. Vine.

W:it^-

Ash or uon-volatile matter. . . .

Protein compounds

Fat

Cellulose (fibre)

Starch .^.

Su^ar r

Other non-nitrogenous matter.

14.1

2.5
23.4

2.0
10.0
37.0

2.0

9.

100.00

13.68
2.75
7.12
1.09

53.71

21.65

100.00

16.02
4.93
8.86
2.34

42.79

25.00

100.00

BEETS, TURNIPS.

133. To estimate the value of tliese for fodder, deter-
minations of water, albuminoids, mineral matters, cellu-
lose, and the total amount of other non-nitrogenous
matters, are important.

For the manufacture of sugar, the estimation of this
ingredient is of greatest importance.

The part of the beet that is insoluble in water consists
mostly of cellulose and pectose, while in the aqueous solu-
tion, sugar, inorganic salts, and albuminoids, are to be
found.

a. Water. — Slice the roots after they have been proper-

258 § 133. FODDER AND POOD.

ly cleaned ; or, if they are very large, select 15-20 from
the lot, cut each one in halves from top to bottom, and
take a thin slice from the inside of each half.

If sugar is to be determined for technical purposes, the
crown and end of the root should be cut off, in the man-
ner practised at the manufactory, before slicing it.

Weigh quickly the whole number of slices thus ob-
tained, to the amount of 500-1000 grms., and dry them
on threads in the drying-chamber at a tetnperature of
60-70° C. Pulverize this dried substance coarsely, mix it
well together, and weigh the whole quantity, determine
hygroscopic water in a portion of 5-6 grms., and keep the
rest in well-stoppered bottles.

h. Non-Tolatilc matter, nitrogen, fat, crude cellulose.

— ^Determine these as directed under Fodder (§ 129, c,
§ 130, h, c, d).

c. Pectose compounds. — These are estimated by the
difference between the weight of the dry substance and
the sum of the weights of the above-named substances in
h, and the sugar.

d. Sugar. — Boil 2-3 grms. of the powdered substance
with several fresh portions of 80-85" |q alcohol, as long as
anything appears to be taken into solution ; pour each
portion of alcohol through a filter that has been dried at
100° and weighed, and finally put the whole insoluble
substance on the same filter, wash it with hot alcohol, dry
it at 100°, and weigh, ignite it, and weigh the ash. The
amount of organic matter, burned off by the ignition,
can then be estimated ; it consists almost entirely of sugar.

To determine the sugar more accurately, add considera-
ble water to the alcoholic solution, heat the mixture on
the water-bath until the alcohol is entirely evaporated, di-
lute the residue to about 300 c.c, add 5-6 c.c. of concen-
trated sulphuric acid, heat the mixture 3 hours on the
water-bath, neutralize the free acid with sodic carbonate,

§ 133. BEETS, TURNIPS. 259

and determine glucose in an aliquot part of the solution,
having first added water, if necessary, to make the volume
of the solution one that can be easily divided into aliquot
parts ; calculate the result obtained for saccharose, if the
root examined was the sugar beet ; in other roots, and in
the sap of plants, glucose is found, as well as cane sugar,
and the determination should be made accordingly (§ 83).

To examine the root in its fresh state for sugar, enclose
a weighed quantity of the finely grated root in a flannel
bag, and press the sap out of it ; weigh the press-cake,
and determine water in one portion of 20-30 grms. by
desiccation at 100° ; on the basis of this determination,
the amount of sugar still remaining in the cake can be
estimated, the solution in the cake being of course of the
same strength as that expressed.

Weigh or measure the sap that was pressed out, and
determine sugar in an aliquot part of it.

In the case of the sugar beet, it may be assumed with
tolerable safety that it contains 94" !„ of water, and we
may therefore express a small quantity of the sap from a
weighed quantity of the grated root, and determine sugar
in 50 c.c. of it, in the usual manner (§ 83).

An approximate estimation of sugar in beets may be
made by determining their specific gravity according to
the method described in § 35, e.

Take 10-12 beets from different parts of the lot, clean
them carefully, cut each one in four equal sections, across
its longitudinal axis, and use the second piece from the
top for the determination of the specific gravity. The
temperature of the saline solution should be about 18° C.

The relation between the specific gravity of the beet
and the percentage of sugar, as well as of total dry sub-
stance, is given in Table YI.

When, in these estimations of sugar with the cupric so-
lution, the solution of sugar is not properly clarified by
the plumbic acetate, heat a measured quantity of it nearly

260 § 133. FODDER AND FOOD.

to boiling, add a few drops of milk of lime, whereby a
heavy precipitate is usually produced ; then filter the
liquid through granular animal charcoal, free from dust,
and repeat this filtration until the solution is sufiiciently
decolorized. If any evaporation of the water is avoided
in the course of this operation, the sugar can be deter-
mined at once in a measured portion of the filtrate ; other-
wise, the coal must be well washed, the filtrate and wash-
ings perfectly mixed, and the estimation of the sugar, for
the whole amount of solution taken originally, based upon
the ratio between the volume of this solution and that in
an aliquot part of which the sugar is determined with the
cupric solution.

e. Ammonia* — Treat 80 c.c. of the sap with enough
plumbic acetate to effect complete precipitation, filter the
liquid, and use 20 c.c. of the filtrate for the determination
by Schlossing's process (§ 47, h).

f. Nitric acid. — Determine this according to Schloss-
ing's process (§ 62, «), in 10-20 c.c. of the concentrated
sap, containing not more than 2-2.5 grms. of organic mat-
ter ; an amount of ferrous chloride, containing 6-7 grms.
of metallic iron, should be used for 1 grm. of dry sub-
stance in the quantity of sap taken.

Hugo and Ernst Schulze found it best to make an alco-
holic extract of from 4-10 grms. of the dried and powder-
ed root, according to its richness in nitric acid, with 90° |(,
alcohol, with the aid of heat ; the extract was evaporated
to dryness, the residue dissolved in water, and the solu-
tion filtered, if necessary ; nitric acid was determined in
this filtrate. {Landwirthsch. Versuchs-iStationen, 9, 447.)

ff. Starcll. — Some roots, and particularly carrots, con-
tain a notable quantity of starch. To estimate it, mash
an amount of the root containing 3-4 grms. of dry sub-
stance with cold water, rinse the mixture into a beaker,
add more water, stir the whole, and let it stand half an

§ 134. POTATOES. 261

hour; decant the supernatant liquid on a dried and
weighed filter, and finally transfer the insoluble residue to
the same filter ; Avash the filter well with cold water, re-
move most of the water from its contents by pressure
between folds of filter-paper, dry the whole at 100°, and
weigh. Treat the filter and its contents with extract of
malt, and determine glucose in the product (§ 81).

POTATOES.

134. Prepare them for examination as directed in § 133,a.

a. Water. — Dry 250-500 grms. of the potatoes, and
determine hygroscopic water also, as directed in § 133, a,
in the examination of roots.

h. Dry substance soluble in water. — Cut several pota-
toes very fine, and crush 30 grms. )f the carefully mixed
sample with cold water, in a mortar, and separate the
soluble from the insoluble part in the same manner as di-
rected in § 133, g.

Dry the insoluble residue at 100° C, weigh it, inciner-
ate it in the muffle (§ 123, c), and weigh the ash ; thus we
have determined the organic and the inorganic matter in-
soluble in water. The difference between the weight of
the dried insoluble residue and the amount of substance
taken gives the weight of soluble matter in it.

Bring the aqueous solution to any easily divisible vol-
ume, and heat about ^ I3 of it to boiling. Albumen is pre-
cipitated, and may be collected on a weighed filter, dried
at 100°, and weighed.

Evaporate the filtrate from the albumen to dryness on
the water-bath, weigh the residue, ignite it, and weigh the
ash ; thus organie and inorganic matters, soluble in
water, are determined.

c. Albuminoids. — Evaporate another third of the solu-
tion almost to dryness, mix the moist residue with calcined

262 § 135. FODDER AND FOOD.

gypsum, dry it at 100-105° C, and ignite the residue
with soda-lime (§ 85).

d. Starch. — Determine this, together with a small quan-
tity of gum, in 2.5-4 grms. of dry substance (§ 79).

For technical purposes, it is often sufficient to determine
the specific gravity of the potato, in order to estimate ap-
proximately the goodness of the tuber, or the amount of
dry substance and starch that it contains.

Determine the specific gravity as directed in § 35, e.
The temperature of the saline solution should be about
16° C The relation between the specific gravity and the
amount of dry substance and starch is given in Table YII.
Potatoes that have been afifected by disease cannot be
examined in this way unless the diseased parts are cut out.

Artichokes may be examined in the same way as
potatoes, except that the aqueous extract of the former
should be more carefully examined for glucose. The
inulin in the artichoke is converted into glucose somewhat
more easily than the starch in potatoes.

SEEDS. MEAL. FLOUR.

135. Seeds are crushed in a mortar or ground to a fine
powder in the steel mill.

a. Water. — Desiccate 5-10 grms. of the powder, and
preserve the rest in well-stoppered bottles.

h. Non-yolatile matter, protein compounds, fat, crude
cellulose. — Estimate these precisely as directed for the
examination of fodder (§ 129, c, § 130, 5, c, d),

c. Dry substance soluble in water.— Determine this

as directed in § 134, 5, with 20 grms. of the powder,

d. Starch. — Follow any of the methods described in
§ ^9.

Or, wash 2 grms. of the powder on a filter, first with
cold water, then with alcohol containing sulphuric acid,

§ 136. MILK. 263

to take out the gluten, and again with water ; then pierce
the filter with the glass rod, wasli its contents into a flask,
tear the filter into shreds, and boil it by itself with water
CQntaining 4 or 5 drops of 20" 1^ sulphuric acid, and finally
add it to the contents of the flask ; the total amount of
solution thus obtained should not be over 100 c.c. ; pro-
ceed as usual with the conversion of the starch into glu-
cose (§ 79).

In most seeds there is bnt little gnm or sugar ; one can
therefore proceed at once to treat the seeds with alcohol
acidified with sulphuric acid, as above, remove the alcohol
by heat, and convert the starch into glucose.

MILK.

136. a. Water. — Boil 50 grms. of the milk with 8
grms. of powdered crystalline gypsum, or with 30-40
grms. of baric sulphate (§ 90, A), and after the coagula-
tion has taken place, evaporate the mixture to dryness on
the water-bath, with constant stirring towards the end of
the operation, and dry the residue at 100° as long as it
loses weight.

Or, the desiccation may be completed on hot sand in
rarefied air (§ 90, g).

h. Total non-YOlatile matter. — Evaporate 30 grms. of
the milk to dryness, with the addition of' a little acetic
acid, and incinerate the residue in the muffle at the lowest
j)ossible temperature.

c. Protein compounds. — These may be estimated by
the remainder left after subtracting the sugar, butter, and
ash, from the total dry substance ; this residue consists
mostly of casein. Or, nitrogen may be estimated in the
usual manner (§ 85) iu the residue left on evaporating 6-7
grms. of the milk to dryness with powdered gypsum or
baric sulphate, as above.

Albumen is contained iu milk in but small proportion ;

264 § 136. FODDER AND FOOD.

in the case of some diseases, it occurs in larger quantity.
To estimate it, coagulate 100 grms. of the milk with ren-
net, at a temperature of about 45° C, filter out the pre-
cipitate, and wash it, and heat the filtrate and washings
to boiling. Collect the precipitated albumen on a dried
and weighed filter, dry it at 100 C, and weigh it.

d. Butter. — Extract the residue obtained in a with
ether (§ 87).

Various other and shorter processes are given for tes-t-
ing the goodness of milk in this respect, in one of which
the cream is estimated by volume.

Provide a shallow glass dish in the form of an inverted
bell-jar, with a ground glass plate to cover it and prevent
evaporation of the milk, and a narrow orifice below, closed
with a glass stopper ; a graduated cylinder holding 100
c.c. will also be needed.

Put 100 c.c. of cooled milk into the dish, and let it stand
24 hours, at a temperature of 12-15° C. ; then loosen the
stopper below, and let the milk flow out from underneath
the cream into the graduated cylinder. After about ^ |^
of the milk has run out, stop the flow for a few minutes,
to allow the cream to collect together somewhat, and then
let the milk flow out again, but only drop by drop, until
the cream appears at the opening ; the quantity by which
the milk now collected in the cylinder is less than the
original 100 c.c. represents the cream, and the percentage
of cream by volume can be estimated. 1"! ^ by volume
corresponds very nearly to one-fourth "[^ of butter in the
milk, by weight.

If a glass dish, like that described above, cannot bo
obtained, any shallow dish that can be well covered will
answer, and the milk can be withdrawn from under the
cream by a small siphon, with a rubber tube and clamp
at the end of the longer arm to regulate the flow of the
liquid.

§ 136. MILK. 265

VogePs optical milk test. — This j^rocess meets with
very general acceptance. It depends upon the fact that
the light is intercepted by water containing a smaller
proportion of milk, the richer the milk is in butter.

The apparatus required consists of a measuring flask,
with a mark on the neck, indicating a capacity of 100 c.c,
a test-glass, for holding a sample of the milk and water
between the eye and the light, which should have parallel
glass sides, ^\ ^ cm. apart, so that the thickness of the layer
of milk looked through will be exactly ^ l^ cm., a pipette
graduated in ^ 1^ cubic centimetres, and holding 4-5 c.c,
and a box about 16 cm. long and wide, with a slit in one
side, in front of which, and 40 cm. distant, the stearin
candle is placed ; the opposite side of this box is so cut
out to fit the face that, when the glass containing the
milk is put in the box, all light can be excluded while an
observation is made, except that coming through the slit
from the candle ; the inside of the box should be painted
black.

To perform the test, fill the 100 c.c. flask with distilled
water up to the mark, add to it 3 c.c. of the well-stirred
sample of the cooled milk, and mix the two together
thoroughly by vigorous agitation ; fill the test-glass with
this mixture, put it in the dark box, and make the obser-
vation, placing the eye close to the test-glass, and the
candle against a dark background. If the light can be
seen, pour the test sample back into the flask, add ^ 1^ c.c.
more of milk, and make another observation ; continue'to
operate in this manner, adding ^ 1^ or ^ \^ c.c. of milk each
time, until the light is no longer visible.

The relation between the number of cubic centimetres
of milk required and the per cent of butter is given in
Table IX. This per cent is calculated by the formula
23:2 _j_ 0.23, in which 7/ = the number of cubic centimetres
of milk required. If 5.5 c.c. or more of milk were used
to produce opacity, it is prob^fele that the milk "^as

12

266 § 136. FODDER AT^D FOOD.

watered. It is rare that less than 3 c.c. of cow's milk will
be needed.

e. Sugar. — Collect the residue, insoluble in ether, in d^
on a dried and weighed filter, dry it at 100° C, boil it four
or five times Avith fresh portions (150 c.c. each) of 80° |„
alcohol, and weigh this insoluble residue on a dried and
weighed filter, after drying it at 100° C. The loss of
weight, after extraction with alcohol, gives the lactose
approximately. The residue on the filter will be mainly
casein and insoluble salts, together with the baric sul-
phate or gypsum, with which the milk was evaporated.

Or, to determine the lactose more accurately, dilute 20
grms. of the milk with twice its volume of water, heat
the liquid to 40° C, coagulate the casein with 4 drops of
acetic acid, collect the coagulum on a linen filter," and
wash it well with water. Dilute the filtrate and washings
to 200 c.c, and determine lactose in the usual manner, in
a measured volume of the liquid, previously filtered if
necessary (§ 84).

f. Lacto-protein, hutter, casein^ etc, — Millon and
Commaille give this process for estimating the protein
compound peculiar to milk, and for the determination of
other substances also.

Dilute 20 grms. of milk with 4 volumes of water, add
5-6 drops of acetic acid, stir the mixture well, filter out
the coagulum, wash it two or three times on the filter with
a^ little water as possible, and then with 40" | „ alcohol.
Separate the precipitate from the filter, diffuse it in abso-
lute alcohol, collect it again on a dried and weighed filter,
and extract the butter by ether containing '(^^ of abso-
lute alcohol, that is poured over the contents of the filter.
Evaporate the etherial extract, to estimate the butter taken
into solution, and dry the casein on the filter at 100° C,
and weigh it.

Heat half the filtrate from the first coagulum, or the

§ 137. BUTTEIl. CHEESE. 267

whey, to boiling, filter out the coagulated albumen on a
dried and weighed filter, wash it first with water, then
with alcohol, and finally with ether, dry it at 100° C, and
weigh it.

To the filtrate add a solution of mercuric nitrate, with
care to avoid an excess of the reagent. Lacto-protein is
precipitated, together with mercuric oxide; collect the
precipitate on a weighed filter, wash it once with water
containing 1°!^ of nitric acid, then with pure water as
long as the filtrate is colored by hydrosulphuric acid, then
with alcohol, and finally with ether; finally dry it at 100°
C, and weigh it. 60" 1^ of it is to be estimated as lacto-
protein.

Determine milk sugar in one-fourth of the whey (§ 84).

Evaporate the remaining fourth to dryness in a plati-
num dish, dry the residue at 100°, and weigh it, ignite it,
and weigh again. Subtract the ash, albumen, lacto-pro-
tein, and milk sugar, from the total amount of matter in
solution in the whey, and call the remainder undetermined
extractive matter.

BUTTER. CHEESE.

137. a. Water. — Dry 50 grms. of the finely divided
substance at 100° C. as long as it loses weight ; butter is
more easily dried if a weighed quantity of quartz sand
is mixed with it.

h. Fat. — Extract this with ether in the usual manner
(§ 87), collecting the insoluble residue on a weighed filter.

c. Casein. — Wash the residue, insoluble in ether, well
with Avater, evaporate the aqueous solution to dryness,
dissolve the residue again in water, and, if any of it is
insoluble, collect this on the same filter, and wash the
whole again; dry the contents of the filter at 100°, and
weigh, ignite, and weigh again, and call the difference
between the first and second weighings, casein.

268 § 138. FODDER AND FOOD.

d. Salt. — By evaporating the aqueous extract obtained
in the preceding operation, or an aliquot part of it, to dry-
ness, and igniting and weighing the residue, the amount
of salt in the butter or cheese may be estimated.

VINEGAR.

188. The only constituent of vinegar which it is usually
desired to estimate quantitatively is the acetic acid.

a. For this estimation, i^roceed as directed in § 70.
Good vinegar should contain about 5° | ^ of this acid.

The vinegar should give no reaction for sulphuric or
hydrochloric acid, after acidification with nitric acid. If
it has been adulterated with these acids, they will of
course saturate a portion of the standard sodic solution.

h. Free sulphuric acid in vinegar may be detected and
determined by adding baric carbonate to it, filtering,
washing the contents of the filter, and then treating the
residue with hydrochloric acid ; the excess of baric car-
bonate that was used will be dissolved by the acid, while,
if mrj free sulphuric acid was present, baric sulphate will
remain undissolved ; it may be washed and weighed in
the usual mamier (§ 59).

§ 139. WOOL. 269

CHAPTER IX.

WOOL.

139i a. The sample for examination.— Take a sample
from each one of several sheep just before the time of
shearing, and after the animals have been washed in the
customary manner, and from the following parts of each
animal — the leaf, the side, the middle of the chine bone,
the withers, the neck close to the nape, the middle of tlie
thigh, and the middle of the belly ; each specimen should
be taken from a spot an inch in diameter, and be cut off
close to the skin, put at once in a large glass tube of
known weight, that can be well stoppered, and weighed
when taken to the laboratory. The number of the par-
ticular animal and the spot from which the sample was
taken should be marked on a label on each tube.

If the wool is to be examined with respect to its phys-
ical properties, or by one who is experienced in handling
it and judging its value, two other samples should be
taken from each animal, and from the same spots, one
before the washing, and the other afterwards, and all
samples should be preserved and labeled in the manner
prescribed above.

The sample from each part of the animal is to be exam-
ined by itself, but if it is desired to determine only the
average quality of the wool of the flock, the several sam-
ples from like parts of the different sheep may be exam-
ined together.

If a sample of unwashed wool is to be examined,
weigh each one, determine the water in a small portion
by desiccation at 100°, and wash the other portion gently
in cold, soft water until the water is no longer made tur-
bid, dry it, and weigh it in the air-dried state. The
subsequent treatment is the same as for the washed wool.

270 § 140. WOOL.

h. Water. — Dry 3-4 grms. at 100° C, and weigh it.

c. Wash a quantity of the wool in a manner similar
to that practiced in the factory. For this purpose pre-
l^are a solution of 3 parts of hard soap and 2 of crys-
tallized sodic carbonate, in 100 of distilled or rain-water,
heat 20 parts of this solution to 50-55°, put 1 part of
wool in it, and stir the mixture gently for 15 or 20
minutes, while the solution is maintained at the same
temperature ; then take the wool out, wash it in severaj
portions of water, dry it in the air, spread it out on fine
wire gauze, tap the gauze gently underneath several times,
pick off adhering particles of foreign matters with the
pincettes, dry the residue at 100° C, and weigh it. If,
after this treatment, the wool still feels greasy, it should
be washed again in a somewhat stronger bath. Finally
extract any remaining fat with carbonic disulphide or
ether, dry the residue again at 100°, and weigh it.

d. Treat another portion of the wool in the reverse
manner, that is, first with ether (§ 87), and then, after
drying and weighing the residue, wash it in the bath of
soap and soda. Determine the fat in the etherial solu-
tion, or an aliquot part of it.

e. Determine the ash in the residue of c and d in the
usual manner (§ 127). Examine this ash for sand by
digestion with hydrochloric acid, and boiling with sodic
carbonate (§ 58).

f. To determine the specific gravity of the j^ure wool
obtained in c and J, weigh it first in air and then in car-
bonic disulj^hide of knoAvn specific gravity (§ 35, 5, d).

TANNER'S BARK.

140. a. Preparation of the sample.— Cut the bark to
be examined, lengthwise, in very thin shavings.
h. Water.— Desiccate 1-2 grms. at 100° C.
c. Tannic acid,— Pour 100 c.c. of Avater over the dried

§ 141. WATER. 271

substance obtained in b, and digest the mixture in a flask,
15 minutes at a boiling heat, filter, and repeat the same
operation twice with the residue. Evaporate this aque-
ous extract to dryness on the water-bath, with the addi-
tion of a few drops of acetic acid, extract the residue
with strong alcohol, filter the liquid, evaporate the filtrate
until the alcohol is expelled, and dissolve the residue in
distilled water; by this treatment pectose is removed
from the aqueous extract. Determine tannic acid in the
solution finally obtained (§ 77).

CHAPTER X.
BEVERAGES.

I.

WATER.

141. For a complete analysis of water, we must refer
to Fresenius's Quantitative Analysis for directions, while
we confine ourselves here to such special determinations
as possess a more direct domestic or agricultural interest.

a. Total Dry Substance in Solution. — Evaporate 500
grms. of the water to dryness, in a platinum dish, at a
temperature at all times below boiling ; dry the residue
at 130° C, and weigh it ; ignite it, moisten the residue two
or three times with a concentrated solution of ammonic
carbonate, drying it each time cautiously ; finally ignite
the residue gently, and weigh the total non-volatile dry
substance.

Or, instead of treatment with ammonic carbonate, dis-
solve the ignited residue in water in the crucible, pass a

272 § 141. BEVEKAGES.

slow current of carbonic acid through it for a while, and
dry the residue for a considerable time at 150-180°.

This determination of organic matter in water is con-
sidered by some good chemists as possessing no great value.

h. Potassa* — The estimation of this in water used for
irrigation is sometimes important. For this purpose,
evaporate 2000-4000 c.c. of the water to dryness, elimi-
nate the silica in the usual way, and the alkalies as chlo-
rides in the filtrate from the silica (§ 93, G).

c. Ammonia. — To determine this in rain-water, evapo-
rate 2000-3000 c.c. down to 200 c.c, after acidifying the
water very slightly with hydrochloric acid, add an excess
of freshly prejDared sodic hydrate, or of baric hydrate, to
the residue, and distil the ammonia off in the usual man-
ner (§ 47, c).

Deteraiine the ammonia in the distillate with the aid of
platinic chloride, or by the indirect process with the
Nessler solution.

To insure greater accuracy, the whole operation should
be repeated without the water, and with the same amount
of sodic or baric hydrate and platinic chloride or Nessler's
solution ; if any ammonia is thus found, it is due to im-
purities in the reagents, and should be subtracted from
the amount obtained in the first experiment.

If the water is a colored one, derived from some other
source, add calcic chloride, sodic carbonate, and a few
drops of potassic hydrate before distilling.

d. Nitric Acid, — Evaporate 2000-4000 c.c. of the water,
after having added some sodic carbonate, filter out the
precipitate, if any is formed, wash it well, evaporate the
filtrate and washings to a small bulk, and determine the
acid by Schlossing's process (§ 62, a).

e. Organic Matter.— Evaporate 100 c.c of the water
down to about 60 c.c, in a flask of 500 c.c. capacity, in
order to decompose ammoniacal compounds by the caTcic

§ 141. WATER. 273

carbonate that is nearly always present, add water till
the original volume is about restored, and proceed to
titrate the solution for the organic matter with potassic
permanganate (§ 91).

A good drinking water should not contain more than
3-4 parts of organic matter in 100,000 parts.

If, on adding to 100 c. c. of the water 2 or 3 drops of
concentrated sulphuric acid and a little of a freshly pre-
pared mixture of potassic iodide and boiled starch, the
water is colored blue, nitrous acid is present, and a correc-
tion must be made in the determination of the organic
matter. For this purpose add 10 c.c. of the dilute sul-
phuric acid to 100 c.c. of the water, and then add joer-
manganic solution till the first trace of a red color appears.
The aniount of the standard solution required for this
must be subtracted from the total amount required in the
first trial.

The presence of nitrous acid in drinking water should,
however, be regarded with suspicion, for it indicates that
the water, perhaps, contained nitrogenous organic matter,
from which it may not yet be entirely freed ; such organic
matter is far more harmful than that containing no nitrogen.

Other prominent methods of making this important
determination of organic matter, and particularly nitrog-
enous matter, in water, have not yet been sufficiently
tested to justify their insertion here, although, without
doubt, good methods will soon be worked up out of the
material now in hand. Many good chemists still allow
some value to the indications that are furnished by the
permanganic test relative to the badness of the water in
sanitary respects, while others have no confidence in it.
Other substances besides nitrous acid may increase the
amount of permanganic solution that is reduced, and so
give too large an amount of organic matter, as ferrous sul-
phate, for instance.

f. Lime* — To determine this base, which, in one form or
12*

2T4 § 141. BEVERAGES.

another, is the source of the largest part of the hardness
of water, add a little hydrochloric acid to 100-500 c.c,
heat the mixture, and precipitate and determine lime with
the aid of aramonic oxalate, in the usual manner (§ 49, a).

Or, by a more speedy though somewhat less accurate
method, to 100 c.c. of the water in a 300 c.c. flask, add
25 c.c, or, if the water is very hard, 50 c.c. of a ^ \^^ atomic
solution of oxalic acid, then add ammonia until the
reaction of the liquid is faintly alkaline, and heat the
mixture until it boils.

After the liquid has cooled, add distilled Avater up to
the 300 c.c. mark, mix the whole well together, filter the
liquid through an unmoistened filter into a dry glass,
putting the first portions of the filtrate on the filter again,
if turbid, as is often the case. To 200 c.c. of the clear
filtrate, in a capacious flask, add 10 c.c. of concentrated
'sulphuric acid, heat the solution to 50-60° C, and deter-
mine the excess of oxalic acid in it with the aid of the
standard permanganic solution (§ 69). By multiply-
ing the number of cubic centimetres of the standard
solution used by 1.5, the amount that would have been
required for the whole solution is obtained. Each cubic
centimetre of the solution of oxalic acid that did not
require to be decomposed by the permanganate, was
engaged in the precipitated calcic oxalate, and corre-
sponds to 0.0028. grm. of lime.

g. Hardness of the Water.— 1. ClarJc's method. This,
though a convenient method of determining the hardness
of water, does not give highly accurate results ; it is,
however, generally used.

The scale of hardness is expressed by the number of
milligrammes of lime in 100,000 mgrs., or 100 grms. of
water, that are required to produce the different degrees
of hardness, and this hardness is estimated by the amount
of soap precipitated from a standard solution of the
same.

§ 141. WATEE. 275

The Standard Solution of Soap. — Mix together 150
parts of lead plaster and 40 parts of potassic carbonate,
exhaust the mass with alcohol, filter the liquid, evaporate
the filtrate on the water-bath, and dissolve the residue in
50 parts of 56" |^ alcohol. Dissolve, also, 0.523 grm. of
pure and dry baric chloride in water, and dilute the solu-
tion to one litre.

Provide a bottle of about 200 c.c. capacity, with a well-
fitting glass stopper, and a mark on the side to indicate a
capacity of 100 c.c, put 100 c.c. of the solution of baric
chloride in this bottle, and add the solution of soap from
a burette or a graduated pipette, with frequent agitation,
until an abundant delicate lather appears that lasts five
minutes. The shaking of the bottle should always be
performed in the same manner ; the best way is to grasp
the stopper and the neck with one hand, and the bottom
with the other, and shake it up and down.

Having tested the strength of the solution of soap,
dilute it with 56" 1^ alcohol to such an extent that 45 c.c.
are necessary to produce the lather with 100 c.c. of the
solution of baric chloride ; this quantity of the latter
solution produces the same degree of hardness as 12
mgrs. of lime.

Exammation of a Sample of Water.— If a hard spring
water is to be examined, put 10 c.c. of it into the bottle
described above, and add distilled water up to the 100 c.c.
mark ; if it is a soft river water, fill the bottle up to this
mark with the water alone ; then add the solution of soap
from the burette, as above. Add at first larger quantities of
the standard solution at a time, but, towards the close,
the agitation should be repeated -after each 0.5 or 1 c.c.
that is added, and finally between each drop or two.

On repeating the experiment, in case but little of the
standard solution was used, take 25 to 50 c.c. of the water,
but not a quantity that will require more than 45 c.c. of
the standard solution ; in this second trial add, at once,

276 § 141. BEVERAGES.

all but 1-2 c.c. of the solution of soap that will be
required, and then allow it to flow in drop by drop only,
until the reaction is ended.

The relation between the quantity of the standard solu-
tion used and the hardness of the water is given in Table
YIII. If the water tested was diluted with distilled water,
the hardness is to be taken as many times greater as the
volume of the water was increased by the dilution.

If a water contains more than 12 parts of lime in
100,000, the first addition of the solution of soap to it
causes the formation of a flocculent precipitate, and it
must be diluted as above before the test is made ; if less
than this proportion of lime is present, only an opalescence
appears in the liquid on adding a drop of the solution of
soap.

"With respect to the hardness of water, we have to dis-
tinguish the total hardness^ which is caused by the total
amount of lime in the water, and \hQ permanent hardness,
caused by salts of lime that are not precipitated when the
liquid is boiled, such as calcic sulphate and chloride. To
determine this permanent hardness, boil 300 to 500 c.c. of
the water half an hour, in a flask of twice the capacity,
replacing the water, as it is evaporated, by fresh distilled
water ; after the liquid has cooled, make its volume the
same as that with which the operation was begun, by
adding more water, mix the whole well together, filter
the liquid, and determine the permanent hardness in an
aliquot part of it, as above.

2t FlecTc's method. — This apparently convenient method
depends upon the fact that, when a solution of soda-soap
in alcohol is added to a solution of a calcic salt, a neutral
sodic salt is formed, and that, as soon as all the calcic salt
is decomposed, the addition of more soda-soap will turn
red litmus blue. (Freeenius^s Zeltschrift, 7, 351.)
. TJie Standard Solutions. — Solittio?i of Soap. — Cut 50

§ 141. WATER. 277

grms. of pure Marseilles soap in tliin slices, pour 500 c.c.
of 74" Iq alcohol over it, and heat the mixtures ; the soap
should he free from sodic carbonate or hydrate, and its
solution should, therefore, give no precipitate or black
color Avith mercurous nitrate. Filter the solution, if it is
not perfectly clear. PrejDare a saturated solution of calcic
sulphate, and to 100 c.c. of it add 10 drops of a solution
of litmus (or cochineal) ; boil the liquid five minutes and
add the standard nitric acid from a burette, drop by drop,
until the blue color is changed to red ; then add the solu-
tion of soap from another burette until the blue color
reappears.

The solution of soap is now to be made of such a
strength that 20 c.c. of it will be required to produce the
blue color, with 100 c.c. of the solution of calcic sulphate.
If, for example, 15 c.c. were required in the above experi-
ment, 5 c.c. of alcohol must be added to every 15 of the
solution of soap to make the standard solution.

100 c.c. of tlie saturated solution of gypsum contain
210 mgrs. of calcic sulphate ; eacli cubic centimetre of
the soap solution, representing 1° of hardness, corre-
sponds, therefore, to l2 mgrs. of calcic sulphate.

The standard nitnc acid is conveniently made of such
a strength that 0.1 c.c. neutralizes 1 c.c. of the standard
solution of soap. 0.05 c.c. of nitric acid, corresponding to
0.5° of hardness, has to be used in excess to produce a
permaAent red ; therefore, 0.5 should be subtracted from
the total amount of soap solution used.

Examination of a Sample of Water. — If the water
contains calcic carbonate, boil 100 c.c. in a beaker or
flask, until the carbonate is precipitated ; then, without
filtering, add 10 droj^s of litmus solution (or cochineal),
and add the nitric acid precisely as in estimating the
strength of the solution of soap, as first made ; the litmus
will not be colored permanently red until all the calcic
carbonate is dissolved ; therefore, the number of cubic

278 § 143. BEVERAGES.

centimetres of acid required for this represents the tem-
porary hardness. After adding the proper quantity of
nitric acid, j^roceed to add the standard solution of soap,
in the same manner as when determining the strength of
this solution with the aid of calcic sulphate.

Suppose that, in treating 100 c.c. of the water in this
manner, 0.2 c.c. of nitric acid were required to produce a
permanent red color, and 8 c.c. of the solution of soap to
change the red to blue; 2 c.c. of the latter were necessary
to decompose the calcic nitrate resulting from the actioii
of the 0.2 c.c. of nitric acid on the calcic carbonate, and
6 c.c. to decompose the calcic sulphate ; subtracting 0.5
c.c, as above directed, for the excess of nitric acid, we
have 2° for the temporary hardness, and 5.5° for the per-
manent hardness of the water examined.

10° of hardness indicates a hard water ; the hardness of
river water is usually from 2° to 6°.

II.

WINE.

142. a. Specific Gravity.— Determine this carefully
with the specific-gravity bottle.

1). Dry Substance ia Solution. — Evaporate 20 grms.
to dryness with gypsum (§ 90, h).

c. Total IVon-volatilc Matters.— Evaporate 200-500
grms. to dryness on the water-bath, and incinerate the
residue in the usual manner ; determine carbonic acid in
the ash.

d. Complete Analysis of the Ash.— This is rarely im-
portant, but may be made according to Scheme I., § 94.

e. Protein Compounds.— Evaporate 100 grms. with
gypsum (§ 90, A), and ignite the residue with soda-lime

(§ 85).

§ 142. WINE. 279

/. Alcohol* —Estimate this in 10 or 25 c.c. of the wine,
adding a few drops of soda, or enough to change the
color of the wine completely, and about 0.06 grm. of
tannin ; the soda neutralizes the free acid, and the tannic
acid prevents frothing. For the manner of conducting
the distillation, see § 87.

g. Sugar. — This may be determined in 100 grms. of
the wine directly, in the usual manner (§ 81), after decol-
oiizing the liquid by contact with 2-3 grms. of bone-black,
and filtering.

Or, the wine may be decolorized iu this manner
(Grifiin). Dilute the red wine to about half the extent
required for the determination of srtgar, add enough milk
of lime to make the liquid alkaline, and agitate the mix-
ture well ; then add about one-tenth as much of a solution
of basic plumbic acetate as was taken of the wine, and
shake the mixture again ; finally add one-third as much
of a solution of alum, containing 1 part of salt in 20 of
water, as was required of the plumbic solution, dilute the
mixture to any volume easily divisible into aliquot j^arts,
mix the whole together by violent agitation, let it stand
until the solid matters settle, and then decant enough of
the supernatant liquid into a dry filter for the determina-
tion of the sugar.

If the wine is a light-colored one, nothing need be
added but sodic carbonate until it is alkaline.

Cane sugar exists in wine only when it has been pur-
posely added. It can be estimated, if present, in the
usual way (§ 83).

If the wine is neutralized with lime, and alcohol added
to precipitate malic and succinic acids, a little baryta-
water will give a precipitate in the filtrate, which is more
or less abundant, according to the amount of sugar pres-
ent (§ 83).

h. Gum (and sugar), etc. — Evaporate 100 grms. of the
wine to a syrup on the water-bath, exhaust the residue

280 § 142. BEVERAGES.

by digestion with several portions of alcohol, as long as
a fresh portion is colored, and estimate the gum in the
insoluble residue as directed in § 80.

Plalf of the alcoholic extract may be evaporated to
dryness, the residue weighed, and then incinerated, and
the ash weighed ; thus the total volatile and non-volatile
(organic and inorganic) matter, soluble in alcohol^ may be
estimated.

Sugar may be determined in the other half of the alco-
holic extract, after adding water and heating the liquid
on the water-bath until all the alcohol is expelled (§ 81). .

i. Tannic acid. — This acts upon the cupric solution,
used in determining sugar, precisely as sugar does, 3.7
parts reducing as much cupric oxide as 5 parts of sugar.
Tannic acid is absorbed when the wine is decolorized by
contact with bone-black ; the difference, then, between the
amount of cupric solution required with and without
treatment with bone-black, will give, approximately, the
amount of tannic acid. But in many cases the wine would
be too dark-colored to admit of a determination of sugar
by the cupric solution without treatment with the decol-
orizing agent, and there are, moreover, other substances
in the wine that are removed by the charcoal, and that,
at the same time, act on the cupric solution. When, how-
ever, the determination can be made, it answers very
well for the comparison of different wines with each
other, since the proportion of the other reducing agents
does not seem to vary much.

h. Free acids. — ^Titrate 100 grms. of the wine with the
standard sodic solution.

Then mix another portion of 100 grms. with clean sand,
and evaporate it to dryness on the water-bath, with con-
stant stirring, and heat it as long as any odor of acetic
acid is evolved ; dissolve the residue in water, and titrate
the solution with the standard sodic solution. The dif-

§ 142. WINE. 281

ference between the amounts of sodic solution required in
the two trials represents the acetic acid.

Estimate 0.06 grm. of acetic acid, HC^HgO^, for every
cubic centimetre of this difference, and 0.075 grm. of tar-
taric acid, H^C^H^Og, for every cubic centimetre of the
sodic solution required after the acetic acid was expelled.

Griffin {Chemical Testing of Wines and Spirits) deter-
mined the free acid as follows, with a ^ 1^^ atomic solution
of ammonia for the standard solution, and an extract of
logwood for the coloring matter.

Take two portions of wine, of 7.5 c.c. each, and add to
each, if it is a white wine, 125 c.c. of water, or, if it is a
red wine, 250 c.c, or more, according to the depth of the
color ; then add exactly the same quantity of the extract
of log\yood to each portion, which gives a color to the
wine very much like that obtained by painting j^aper
with raw sienna; add the alkaline solution from the
burette to one portion, keeping the other at hand for
comparison, with constant stirring ; when the color sud-
denly changes to a reddish-brown, like that obtained by
hurnt sienna on paper, the point of saturation is reached.
Now, repeat the experiment with the other portion of the
wine, adding all but 2-3 c.c. of the required quantity of
standard ammonic solution at once, and then drop by
drop, until the acid is saturated.

Each cubic centimetre of the alkaline solution required
corresponds to 0.1 of an equivalent of free acid, or, if we
call it all tartaric acid, as it is, mostly, 0.0075 grm ; and
in this case the number of cubic centimetres used gives
at once the number of grammes of acid (tartaric) in the
litre of wine.

Good wines contain 4-6 grms. of free acid in the litre
(300-400 grains of crystallized tartaric acid, Griffin). In
poor wine years, the proportion of free acid often rises
as high as 10-12 grms. in the litre.

I Tartar.— Add 40 c.c. of 90"! alcohol to 20 c.c. of

282 § 142. BEVERAGES.

the wine, let the mixture stand several days in a well-
closed bottle, and then titrate 30 c.c. of the clear liquid
with the standard sodic solution ; subtract 0.3 c.c. from
the amount of soda required, and then subtract this re-
mainder from the amount that would be required, as in
Jc^ to neutralize the total free acid in 10 c.c. of wine ; this
second remainder represents the quantity of acid that was
removed from the wine by treatment with alcohol ; for
each cubic centimetre of this remainder calculate 0.1881
grm. of tartar.

Griffin estimated tartar by evaporatmg 100-200 c.c. of
the wine to dryness, incinerating the residue, determining
potassic carbonate in the ash with the aid of the standard
acid, and allowing one equivalent of tartar for every
equivalent of potassic carbonate thus found in the ash.

He estimated it also by adding 25 c.c. of alcohol and
as much ether to 10 c.c. of wine, letting the mixture
stand 24 hours, collecting the precipitate on a dried and
weighed filter, drying it at 100° C, and weighing it ;
all but about 0.002 grm. of the tartar will be precipitated
in this way.

m. Total tartaric acid. — ^Evaporate 100 c.c. of the wine
to about half its volume, precipitate the acid by lime-
water in slight excess, filter the precipitate out, boil it
with a solution of potassic carbonate, filter the liquid,
evaporate the filtrate somewhat, acidify it with acetic acid,
precipitate the potassic tartrate with considerable alcohol,
and collect and treat the precipitate as directed in § 71.

n. Malic acid. — This is contained in the filtrate from
the calcic tartrate in m. To determine it, evaporate this
filtrate down to one-third, and j^recipitate the calcic malato
with alcohol, as directed in § 73. As this precipitate will
contain also the sulphuric acid, if any is present in the
wine examined, a determination of this acid should be
made in a portion of the wine, in the usual manner ; then
estimate the amount of calcic sulphate, CaSO^, 2Iifi, in

§ 142. WINE. 283

the precipitate obtained as above with alcohol ; the re-
mainder, after subtracting this, may be reckoned as calcic
malate, although it may contain a little succinate.

The acetic acid, malic acid, and tartar, taken together,
correspond very nearly to the amount of soda used in Ic^
to determine the free acid, each equivalent of tartar neu-
tralizing one equivalent of soda.

0, Free snlphuric acid, if present in the wine under
examination, may be detected and determined in the same
manner as directed in § 138, h.

p. Total alkalies* — These may be estimated in the ash
obtained in c, or in the following manner.

To the remaining 30 c.c. of the filtrate from the pre-
cipitate by alcohol in /, add 5 c.c. of an alcoholic solution
of tartaric acid, whose strength is accurately known, let
the mixture stand several days, and titrate 25 c.c. of the
clear supernatant liquid with the standard sodic solution ;
the rest of the j^otassa, not precipitated in ^, and the soda,
have crystallized out, with an equivalent quantity of the
tartaric acid that was added; this quantity of acid will be
represented by the difference between the amount of sodic
solution used in this trial, and that which would be re-
quired to neutralize the free acid already in the solution
(see I), plus the 5 c.c. of tartaric acid added. For each 2
c.c. of this difference estimate 0.0471 grm. of potassa and
add it to the amount in the tartar obtained in /.

The average composition of v/ine, according to Nessler,
who examined a large number of European wines, is as
follows: Alcohol, 7- 10° |„; Sugar, 0.1 _ 0.2° |„; Free acid,
estimated as tartaric, 0.4 - 0.8°| ^ ; Malic acid, 0 - 0.3° |„ ;
Acetic acid, 0-0.3°|^; Tannic acid, 0.02 - 0.05°|,.
Total dry substance in solution, 1.5 — 2°|q.

284

TABLES.

TABLE I.

THE METRIC SYSTEM OF WEIGHTS AND MEASURES.

1.

Measures of Length.

1 Metre = 1 Metre.

1 Decimetre = 0.1 "

1 Centimetre = O.Ol "

1 Millimetre = 0.001 "

1 Metre = 39.37 Inches.

1 Centimetre = 0.3937 Inch.

1 Foot = 30.48 Centimetres.

1 Inch = 25.4 Millimetres.

The accompanyinjr scales, copied from Professor
H. A. Newton's little pamphlet (The Metric
System of Weiuhts and Measures, with Tables.
Prepared for the Smithsonian Institution), ex-
hibit the relative maj^nitude of the divisions of
the metre and inches.

2.

Measures of Volume.

1 Cubic metre
1 Cubic decimetre
1 Cubic centimetre
1 Cubic centimetre
1 Litre

1 Gallon (imperial)
1 Gallon (wine)
1 Hectolitre

1000 Litres.

1. Litre.

0.001 Litre.

0.06103 Cubic Inch.

0.880(56 Quart.

4.5435 Litres.

3.79 Litres.

2.84 Bushels.

3.

The Weights of the Metric System.

1 Kilogramme
1 Hectogramme
1 Decagramme
1 Gramme
1 Decigramme
1 Centigramme
1 Milligramme
1 Kilogramme
1 Gramme
1

1 Pound
1 Ounce
1 Grain

1000.
100.

Grammes.

10.

((

L

Gramme.

0.1

0.01 "

0.001 "

2.2046. P'ds (avoirdupois.)
"^■^-"■. Ounce "

0.035
15.43
453.6
28.3
64.8

— Grains.
.Grammes.

.Milligrammes.

_

^

*

— '

rrz

— <

__^

:=

—

■ —

^

—

— ■

—

=

—

~ •

__

—

— ■

_ —

~

—

-

"

CP

—

—

t-» —

5 —

t^

Abbreviations.

Centimetre .•

Millimetre

Cubic centimetre

Kilogramme

Gramme

Milligramme

.Cm.
Mm.
.C.c.

.Kilo.
Grm.
.Mgr.

TABLES.

285

TABLE II.

THE ATOMIC WEIGHTS OF THE ELEMENTS CONCERNED IN
THE QUANTITATIVE PROCESSES DESCRIBED IN THIS BOOK.

Aluminium, AI 27.5

Barium, Ba 137.0

Calcium, Ca 40.0

Carbon, C 12.0

Chlorine, CI 35.5

Copper, Cu 63.5

Iron, Fe 56.0

Magnesium, Mg 24.0

Manganese, Mu 55.0

Nitrogen, N 14.0

Oxygen, 0 16.0

Phosphorus, P 31.0

Platinum, Pt 197.1

Potassium, K 39.1

Silicon, Si 28.0

Silver, Ag 108.0

Sodium, Na 23.0

Sulphur, S 33.0

TABLE III.

FACTORS FOR ESTIMATING THE SUBSTANCE SOUGHT
FROM THE COMPOUND OBTAINED.

Compound
obtained.

Formula.

Substance sought.

Formula.

Factor.

Al,03
NH3

(NH4),PtCl6

(NH4)2PtCla

(NH4)2PtCl6

AgCl

AgS

BaSOi

((
CaCOa

u
u
CaC4H406

CaS04
COa

u
u

Clay

AI2O3, 2Si02
2H2O

N

NH3
(NH4)20

S
SO3

s

Ca

CaO

CaS04,2H20

H2C4H4O5

C4H4O4

CaO

CaCOs

CaHaOa

Ammonia

Ammonio -platin-

Nitrogen

3.5150
0.8335

0 0763

Ammonio -platin-
ic chloride

Ammonio -platiu-
ic chloride

Argentic chloride

Argentic sulphide

Baric sulphate...

u u

Ammonic oxide.

Nitrogen

Chlorine

Sulphur

0.1165

0.0638
0.3474
0.1481

Sulphuricanhy- )

dride \

Sulphur

0.3433
0.1373

Calcic carbonate.

Calcium

Calcic oxide )

(lime) \

Calcic sulphate

(cryst.)

0.4000
0.5600
1.7200

Calcic malate

Calcic sulphate..
Carbonic acid

u u

Malic acid

Malic anhydride.
Calcic oxide )

(lime) ]

Calcic Carbonate.
Calcic hydrate...
Humus

0.7791
0.6744

0.4118
2.2730
1.6820
0.4703

286

TABLES.

TABLE IIL— {Continued.)

Compound

■

obtained.

Formula.

Substance sought.

Formula.

Factor.

Ferric oxide

FcaOs

Ferrous oxide...

FeO

0.9000

U 11

FcaPaOg

Iron

Fe
Fe

0 7000

Ferric phosphate.

Iron

0 5298

((

Phosphoric an- )
hydride [

P2O5

0.4702

Ferrous oxide . . .

FeO

Ferric oxide

FeaOa

1.1110

u

Iron

Fe
CoHooO.,

0 7780

Glucose

Saccharose

0 9500

u

CJIioOs

Starch

C12H20O10
HaCeHioOe

0 9000

Lactic anhydride.

Lactic acid

1.1110

Maijjnesic pyro-

pliospliate

Mg,V,0,

Magnesic oxide..

MgO

0.3604

Maji^nesic pyro-

Phosphoric anhy-

phospliate

MgaPaOv

dride

P2O5

0.6396

Magnesic pyro-

Tricalcic phos-

phospliate

MgaPaOj

phate

CaaPaOs

1.3960

Mangauous mau-

g;anic oxide

MuaOi

Manganous oxide

MnO

0.9301

Mani^anous man-

<i;anic oxide... ,

MusOi

Manganic oxide.

MusOa

1.0350

Nitrogen

N

Ammonia

NH3

1.2140

<(

a

Protein com- )
pounds. ......

6.2500

Phosphoric anhy-

Tricalcic phos-

dride

P2O5

phate

C^P,03

2 1830

Platinum

Pt

Ammonia

0.1725

''

u

Potassium

K

0.3968

Potassic chloride.

KCl

Potassium

K

0.5241

(( ((

"

Potassic oxide.. .

K2O

0.6314

Potassic oxide

Potassa feld- J
spar ]

K2O, SSiOa,

(potassa)

K2O

AI0O3, 3SiOo

5 . 9150

Potassic sulphate

K2SO4

Potassium

K

0.4489

Potassic oxide...

KoO

0.5408

Potassic tartrate.

KHC4H40e

Tartaric anliy- )
dride j

041X405

0.7018

Tartaric acid

H2C4H4O6

0.7974

Potassio - platinic

chloride

KaPtCle

Potassium

K

0.1602

Potassio - platinic

chloride

KaPtCle

Potassic oxide...

KoO

0.1929

Potassio - platinic

chloride

KaPtCls

Potassic chloride.

KCl

0.3055

Sodic chloride...

NaCl

Sodium

Na
NaaO

0 3932

a u

Sodic oxide

0.5299

Sodic oxide (soda)

NaaO

Soda feldspar. . ]

NaaO, 3SiO^
AI2O3, SSiOa

8.4680

Sodic sulphate, . .

NaaSO*

Sodiwm

Na
NasO

0 3239

u Ki

Sodic oxide

0.4366

Sulphuric anhy-

dride

SO3

H2C4H40«

KHC4H4O.

1.8750
1.2540

Tartaric acid

H2C4H4O8

Tartar

TABLES.

287

J^ABLE lY.

ESTIMATION OF TANNIC ACID IN BARK.

Sp. Gr. at

«|oOf

Sp. Gr. at

°|oof

Sp. Gr. at

°loOf

Sp. Gr. at

°|o of

15° C.

tannic

15° C.

tannic

15° C.

tannic

15° C.

tannic

acid.

acid.

acid.

acid.

1.0000

0.0

1.0064

1.0124

3.1

1.0188

4.7

1.0004

0.1

1.00S8

1.7

1.0128

3.2

1.0192

4.8

1.0008

0.3

1.0072

1.8

1.0132

3.3

1.0196

4.9

1.0012

0.3

1.0076

1.9

1.0136

3.4

1.0201

5.0

1.0016

0.4

l.OOSO

2.0

1.0140

3.5

1.0020

0.5

1.0084

2.1

1.0144

3.6

1.0024

0.6

1.0088

2.2

1.0148

3.7

1.0028

0.7

1.0092

2.3

1.0152

3.8

1.0032

0.8

1.0096

2.4

1.0156

3.9

1.0036

0.9

1.0100

2.5

1.0160

4.0

1.0040

1.0

1.0104

2.6

1.0164

4.1

1.0044

1.1

1.0108

2.7

1.0168

4.2

1.0048

1.2

1.0112

2.8

1.0172

4.3

1.0052 ■

1.3

1.0116

2.9

1.0176

4.4

1.0056

1.4

1.0120

3.0

1.0180

4.5

1.0060

1.5

1.0184

4.6

TABLE V.

PROPORTION BY WEIGHT OF ABSOLUTE ALCOHOL IN SPIRITS
OF DIFFERENT SPECIFIC GRAVITIES AT 15.5° C. (FOWNES.)

Sp. Gr.

"lo

Sp. Gr.

°lo

Sp. Gr.

"lo

Sp. Gr.

°lo

0.9991

0.5

0.9802

13

0.9638

26

0.9416

39

0.9981

1

0.9789

14

0.9623

27

0.9396

40

0.9965

2

0.9778

15

0.9609

28

0.9376

41

0.9947

3

0.9766

16

0.9593

29

0.9356

42

0.9930

4

0.9753

17

0.9578

30

0.9335

43

0.9914

5

0.9741

18

0.9560

31

0.9314

44

0.9898

0

0.9728

19

0.9544

32

0.9292

45

0.9884

7

0.9716

20

0.9528

33

0.9270

46

0.9869

8

0.9704

21

0.9511

34

0.9249

47

0.9855

S

0.9691

22

0.9490

35

0.9228

48

0.9841

10

0.9678

23

0.9470

36

0.9206

49

0.9828

11

0.9665

24

0.9452

37

0.9184

50

0.9815

12

0.9653

25

0.9434

38

288

TABLES.

TABLE YI.

ESTIMATION OF SUGAR AND TOTAL DRY SUBSTANCE IN THE
SUGAR BEET, BY THE SPECIFIC GRAVITY OF THE BEET.

Sp. Gr.

"lo

Total

Sp. Gr.

1o

Total

Sp. Gr.

u"'"

Total

at

Sugar.

dry eub-

at

Sugar.

dry sub-

at

Sugar.

dry sub-

18° C.

staiice.

18° C.

stance.

18° C.

stan-ce.

1.014

7.00

12.0

1.038

11.00

17.3

1.060

13.75

20.25

1.016

7.50

12.5

1.040

11.25

17.6

1.062

14.00

20.50

1.018

8.00

13.0

1.042

11.50

18.0

1.084

14.25

20.75

1.020

8.25

13.5

1.044

11.75

18.25

1.066

14.50

21.00

1.023

8.75

14.0

1.046

12.00

18.5

1.068

14.75

21.25

1.024

9.00

14.5

1.048

12.25

18.75

1.070

15.00

21.50

1.026

9.50

15.0

1.050

12.50

19.00

1.028

9. To

15.5

1.052

12.75

19.25

1.030

10.00

16.0

1.054

13.00

19.50

1.032

10.25

16.3

1.0.56

13.2;5

19.75

1.034

10.50

16.6

1.058

13.50

20.00

1.036

10.75

17.0

1

TABLE YIL

ESTIMATION OF STARCH AND TOTAL DRY SUBSTANCE IN
POTATOES, BY THE SPECIFIC GRAVITY OF THE TUBER.

Sp. Gr.

Total

Sp. Gr.

Total

Sp. Gr.

Total

at

Starch.

dry Bub-

at

Starch.

dry sub-

at

Starch.

dry sub

18° C.

stance.

18° C.

stance.

18° C.

stance.

1.060

9.54

16.96

1.082

14.50

22.07

1.106

20.13

27.86

1.062

9.98

17.41

1.084

14.96

22.54

1.108

20.61

28.36

1.064

10.42

17.87

1.086

15.42

23.02

1.110

21.09

28.86

1.066

10.87

18.33

1.088

15.88

23.50

1.112

21.57

29.35

1.088

11.32

18.79 i

1.090

16.35

23.98

1.114

22.05

29.85

1.070

11.77

19.26

1.092

16.81

24.46

1.116

22.54

30.35

1.072

12 22

19.72

1.094

17.28

24.94

1.118

23.03

30.85

1.074

12.67

20.18

1.096

17.75

25.42

1.120

23.53

31.36

1.076

13.12

20.65

1.098

18.23

25.91

1.122

24.01

31.86

1.078

13.58

21.13

1.100

18.70

26.40

1.124

24.50

32.36

1.080

14.04

21.60

1.102

19.17

26.88

1.126

24.99

32.87

1.104

19.65

27.37

1.128
1.130

25.49
25.99

33.33
33.90

TABLE JX.

HARDNESS OF WATER.

C.C. of

Hard-

C.C. of

Hard-

C.C. of

Hard-

C.C. of

Hard-

soap

ness or

soap

ness or

soap

ness or

soap

ness or

solution

Mgr.

solution

Mgr.

solution

Mirr.

solution

Mgr.

used.

CaO.

used.

CaO.

used.

CaO.

used.

CuO.

3.4

0.5

15.1

3.5

26.3

0.5

36.7

9.5

5.4

1.0

17.0

4.0

28.0

7.0

38.4

10.0

7.4

1.5

18.9

4.5

29.8

7.5

40.1

10.5

9.4

2.0

20.8

5.0

31.6

8.0

41.8

11.0

11.3

3.5

22.6

5.5 1

33.3

8.5

43.4

11.5

13.2

3.0

24.4

6.0 i

35.0

9.0

45.0

13.0

TABLES.

289

TABLE VIII.

PER CENT OF BUTTER IN MILK, BY VOGEL'S OPTICAL .MILK

TEST.

C.C. of

"In of

C.C. of

o|o of

! C.C. of

°|oOf

C.C. of

•^lo of

milk re-

butter.

milk

butter.

1 milk

butter.

milk

butter.

quired.

used.

used.

used.

2.50

9.51

4.50

5.38

0.50

3.80

8.50

2.96

2.75

8.73

4.75

5.13

6.75

3.06

8.75

2.88

3.00

7.90

5.00

4.87

7.00

3.54

9.00

2.80

3.25

7.41

5.25

4.66

7.25

3.43

9.25

2.73

3.50

G.80

5.50

4.45

7.50

8.33

9.50

2.67

3.75

0.44

5.75

4.26

7.75

3.22

9.75

2.61

4.00

0.03 1

0.00

4.09

8.00

3.13

4.25

5.70 !

6.25

3.94

8.25

3.04

TABLE X.

COMPOSITION OF AGRICULTURAL MATERIALS AND PROD-
UCTS IN 1000 PARTS OF THE SUBSTANCE.

From this Table the student may gain some idea of the
chemical composition of the m.ore important substances
relating to agriculture ; although since this composition
varies so. widely with varying circumstances, no great
degree of precision can be claimed for statements of so
general character, with whatever care they may be pre-
2>ared.

The extreme and the average composition are given ;
the latter is to be taken, however, as indicating not the
real mean of all the reliable analyses of the substance
that have been made, but rather as an approximation to
the proportion of each clement or compound that is gen-
erally found in the substance ; in some cases the propor-
tion of a component ranged too evenly from one limit to
the other of the extremes to admit of estimating any
iaverage of this kind. Fuller details may in some cases
bo found in the admirably arranged tables at the end of
Prof. Johnson'r; " IIow Crops Grow."
13

290

TABLES.
TABLE X.

d

Il

d

d

i

i

ft

d
6

&
S

i

<

i

O

02

Ashes, coal
(anthracite).

22.

87.

14.
57.

23.

2.
30.

350.
430.

52.
130

437.
545.

50.*

15.

380.

80.

500.

Ashes, coal
(bituminous).

15.
147.

0
25.

0
23.

10.
230.

30.

7.
14.

10.

225.
350.

23.

258.

269.
624.

70.*

1 293.

60.

481.

Ashes, peat.

20.
220.

0

200.

U
95.

10.

580.

200.

0
160.

10.
170.

0

730.

10.
7C0.

70.*

8.

4.

20.

30.

Ashes, wood.

2.*

28.

28.
220.

115.

20.
160.

75

0
15.

270.
500.

16.
245.

70.

6.

80.

5.

60.

380.

29.

32.

Bone ash.

0
2.5

0.3

510.
550.

8.
14.

530.

10.6
5.
9.

8.5

5.— 10.

Bone-black.

30.
40.

58.
880.

"soo"

t

t

275.
430.

42.
52.

400.

7.

50.

Bone meal.

47.
167.

520.
680.

^

t

260.
360.

11.0
0.7

5.

2.8
15.5

75.

600.

325

10.

Cement (hy-
draulic).

1.

11.3.

7.

0
17.

550.
628.

602.

0
22.

53.
94.

4.5.

61.

.229.
260.

6.3

10.4

73.

33.

240.

Cheese.

95.
520.

5.
67.

6.(?)

7.

380.

43.

2.5

38.

0.3

0.1

Clay.

0
330.

130.

0
33.

19.

0

27.

9.

0
183.

0
40.

100.
390.

0
230.

150.
770.

20.

10.

280.

90.

480.

(3)

20.
100.

"35^

3.

58.

5.

7.

40 1 '^

10.
50.

30.

Coprolites.

460.
360.

15.

20.-60.
40.

Excrements,
Bolid(Herbiv).

obb.
906.

764.

11.

58.7

0.77
4.8

I). 26
1.9

0.009
0.08

1.4
10.7

4.6

1.
3.

2.5

0.43
1.4.

16.
29.4

25.

3.

0.9

0.05

1.0

21.

Excrements,
Bolid (Man).

708.
S30.

22.
34.

2.5

1.4
i.

1.67

0.18
1.2

0.6

5.8
7.2

2.9
3.6

0.6.

1.9
2.4

SOO.

28.

6.4

3.2

2.1

In 1000 parts of the fuel.— t Possibly present.
33; KnO and NaaO usually 0.— (2) Mn, 0—0.3;
Fluorine, 0—50 ; average 30.

— (1) Fluorine. 36 — 40, average
K2O and Na^O mostly 0.— (3)

TABLES.

TABLE IL.— [Continued.

291

i

6

6

■ o

02

d

125

iilM

i

Ashes, coal (an-
thracite),

1

0
tr.

Ashes, coal
(bituminous).

u.

84.

0.
66.

50.

10.

Ashes, peat.

0.
370.

0.

80.

0
306.

0
65.

50.

30.

10.

Ashes, wood.

7.8
57.

18.
48.

t

4.

50.

Bone ash.

tr.

380.
400.

390.

14.

40.

30.

Bone-black.

40.

100.
380.

300.

15.
27.

5.
32.

7.

17.

Bone meal.

180.
280.

do.

:28.
50.

38.

t

1

220.

1

Cement (.hy-
draulic).

0.

18.8

10.2

Cheese.

11.5

t

t

80.
440.

240.

lOJ.
tiOO.

310.

Clay.

Coprolites.

7.<)
10.6

9.0

30.
380.

1.
67.

traces

0
25.

230.

30.

Excrements,
solid (Herbiv).

0.47

1.58

2.2
5.5

t

t

2.2

9.0

17.
23.

86.
110.

80.
110..

10.
13.

0.87

3.6

4.7

20.

95.

95.

10.

Excrements,
solid (Man).

0.3

o.y

8.5
10.9

t

t

4.

t

t

t '

t

0.6.

9.9

1

t Present.— T^ Possibly present.

292

TABLES.

TABLE X.—lC'oniinued.

M

d

d

s

d

i

<

g

Flesh.

446.
590.

10.
37.

4.1
5.2

0

1.

0.2
0.8

0.2
0.5

0.4

0.1
0.3

524.

22.

4.5

0.7

1 0.3

0.2

Fodder, dry,
graminacese.

118.
180.

24.
111.

?

0.13
0.4

150.

66.

17.1 i 4.7

7.7

3.3

0.2

19.7

Fodder, dry,
legumiuosffi.

110.
200.

45.

80.

10.6
19.5

0
4.7

1

15.
31.

19.

2.6
7.0

5.0

0.3
1.7

0.0
2.'7

160.

70.

15.8

1.5

0.36

1.5

Fodder,:,'reen,
graminaccse.

090.
870.

7.
21.

5.3
11.6

0.1
1.6

1

0.7

2.7

0.3
1.9

t

2.1
12.3

745.

18.

7.

0.5

1.5

0.7

7.3

Fodder, <,n-eeii,
legnmiuosse.

740.
850.

10.
20.

1.0
6.6

0
1.1

0
2.G *

3.0

8.5

0.6
1.6

t

0.1
O.G

804.

12.

1.5

0.4

4.9

1.0

0.4

(1)
Fruits.

760.

880.

2.
9.

1.0
2.4

0
0.7

1

i

0.1
0.4

0.2

0.08
0.33

820.

4.

2.0

0.3

0.3

0.19

Guano,

100.
200.

330.
400.

16.0
30.0

12.

62.
100.

140.

344.

20.0

35.

12.

8.

12.

Gnano,
phosphatic.

10.
140.

100.

780.
950.

0
12.0

0

39.

498.

TqoT

0
21.

4.

89.

0
54.

0
13.

890.

2.5

6.

2.

3.7

Gypsum.

188.
205.

197.

•

■293.
325.

309.

tr.

tr.
.50.

8.

21.

0.03
1.12

0

0.7

410.
550.

3.4
15.0

1.7
10.

2. -40.

0.2

500.

8.

660.
710.

34.

78.

1.2
12.0

0.2

2.8

2.
15.

0.5
1.7

7.5
18.0

farm-yard.

1.7- 8.

680.

58.

8.0

1.2

11.

1.0

3.

14.0

750.
790.

70.
73.

sT

O.G
0.8

0.7

10.
19.

1.8
3.8

17.
23.

farm-yard.

770.

72.

15

1.6

6.7

22.

Han. ''^

13.
100.

30.

tr.
14.8

1.0

Ir.
15.

0
0.99

2.

520.

3.
220.

^

30.-90.

50

♦ In the dry substance, t Present. 1 Possibly present. (1) Free acid, esti-
mated as malic acid, 1.0—20.0; averasje 8.6.— (2) Oxalic acid, 58—80 ; averajjc 60.
ITric acid present.— (3) Fluorine, traces. Sand 8— 47— (4) Insoluble silicates
and sand, 50—850.

TABLES.

293

TABLE

X.—[C'onimued.

i

O

i

02

O

^

11

III

Flesh.

0
0.4

4.3

5.8

t

0.1

0.7

t

123.
174.

144.

210.
397.

5.0

0.4

299.

Fodder, dry,
•jraminaceae.

3.3

T

1.7
3.3

t

30.
180.

170.
400.

225.
514.

12.
56.

3.4

4.1

2.5

5.3

90. 260.

410.

28.

Fodder, dry,
leguminosse.

1.5
5.3

2.8

4.7
9.0

u

0.031

0.9
2.7

1.3
2.1

t

72.
190.

140.

190.
400.

280.

150.
480.

12.
55.

6.5.

1.8

1.5

330.

30.

Fodder, <!;reeu,
graminaceae.

U.2
1.2

1.3
2.4

tr.

0.3

0.8

0.5

0.4
1.9

1.0

t

17.

60.

30.
170.

35.
230.

3.
15.

0.7

1.7

30.

90.

129.

10.

Fodder, green,
leguminosae.

0.2
2.2

0.9
2.0

0.007
5.0

0.3

0.8

0.2
1.0

t

22.
72.

30.
160.

50.
140.

4.

9.

0.8

1.4

0.5

0.4

28.

60.

75.

6.

Fruits.

0.4
0.7

0.5

0.1
0.4

t

3.2

8.0

s^o"

28.
117.

49.

14.
120.

*

64.

0.2

0.1

0.2

Guano,
ammoniacal.

60.
137.

80.
170.

110.

7.

100.

Guuuo,
phosphatic.

0
•270.

170.
420.

0
5.

0
15.

0

8.

tr.
40.

G.

340.

3.2

1.5

Gypsum.

il8.
160.

tr.
30.

140.

Limestone.

0.;^

G.7

0.03
12.0

310.
140.

0.32
1.76

0
1.6

2.0

0.8

too.

Manure, fresii
farm-yard.

1.0
3.0

12
3.0

t

0.6
2.0

0.8

4.0
7.4

6.0

t

+

t

t

2.0

2.8

•

Manure, rotted
farm-yard.

1.2
2.4

"iTs"

3.4
4.5

t

0.2
1.6

6.0

3.9

0.9

Marl.

tr.
15.

Ir.
5.

30.
450.

tr.

* Sugar.— t Present.^l Possibly present.

294

TABLES.

TABLE

X.-[Cmlinued.

d

^<

d

d

i

^

d

<

o

Milk.

8G0.

875.

7.
8.5

~0~

0.2

870.

7.3

1.7

1.5

(1)
Phosphorite
(Apatite).

4.
25.

0
12.6

0
5.0

200.
550.

0
2.3

1.8

.

0
66.

0.37—90.

15.

5.6

3.0

440.

50.

Plants, cereal;
grain.

126.
148.

7.
39.

3.3
5.5

4.6

0.2
1.0

0.5

tr.
3.4

0.14
10.

1.8
2.2

0
0.6

0.3
12'.

142.

20

0.6

1.9

0.18

Plants, cereal:
straw.

90.
225.

40.
5G

4.9
16.6

0
3.5

tr.
1.5

2.3
5.0

0.4
2.6

.02
2.11

18.

150.

45.

6.0

2.5

3.6

1.4

1.0

25.

Plants, com-
mercial.
(Hops, tobac-
co, etc.)

100.
300.

28.
198

5.2
54.1

0.9
7.3

5.
73.

8.

2.0
20.7

.08
3.0

0.8
19.

220.

.50.

15.0

1.6

3.0

1.74

Plants,
Icc^iimc ;
seeds.

128.
148.

17.
35.

6.3
12.0

0.4
6.0

0.6
2.7

0.4
2.1

0.
0.48

0.2
0.4

144.

25.

9.8

1.0

1.5

1.7

0.15

0.3

Plants,
le,i,'ume ;

100.
190.

150

lis.
584.

50.

9.7
25.9

18.9

1.1
3.9

2.6

9.5
25.

1.9
4.6

0.09
0.2

2.4
3.1

15.

3.0

0.13

2.7

Potatoes ;
tubers.

150.
800.

775.

5.6
46.

10.

5.6
6.7

6.1

0.1
0.4

0.2
0.4

0.25

0.3
0.4

0.04
0.06

0.05

0.2

0.25

0.35

Potatoes ;
tops.

770
320.

11.
16.

0.7
2.3

t

5.1
5.5

5.3

2.6
2.7

2.65

0.5

8.5

797.

14.

1.5

0.21

Root-crops ;
roots.

754.

920.

6.
10.

1.9

4.3

0.8
2.0

0.4
0.9

0.7

0.1
0.7

0.4

0.01
0.29

0.1
0.3

875.

8.

3.5

1.0

0.09

0.2

Root-cropa ;
tops.

7ti5
920.

15.
33.

3.2
6.0

0.5
6.0

1.7

8.6

0.4
3.3

0.15
0.28

0.1
2.6

85

17.

4.1

1.5

4.8

1.3

0 26

1.0

Salt.

12.
63.

937.
988.

0
2.3

t

890.
i)94.

975.

1.15
9.7

0.2

2.8

0

tr.

0
tr.

53.0

34.

963.

2.2

8.0

1.7

Saltpetre
(Chili).

1.
20.

t

330.
358.

340.

1.0

•

10.

980.

1.0

29.0

t Present.— 1 Possibly present.— (1) Fluorine 0—49 ; averase 28.— (2) NaOg,
usually 0.

TABLES.

295

TABLE X.—lConiinued.

i

0

s'

m

5

^

2 a!

11

Id

Ill

1

Milk._

0.7

24.

68.

38.

29.
83.

47.*

22.

60.

0.1

1.9

35.

Pliosphorite.
(Apatite).

tr.

300.0
400.0

360.0

3.0
43.0

0.
5.0

25.0

Plants, cereal ;
grain.

0.1
0.5

5.5
10.0

tr.

6.8

0.4
1.7

0.18
0.27

19.

42.5

526.
270.

7.
165.

500.
765.

5.

70.

0.3(5

8.0

1.0

0.2

20.0

120.

60.

640.

Plants, cereal ;
straw.

0.9
2.5

1.4
3.8

0
5.2

0.9
4.0

1.2
1.3

1.7
4.2

6.
100.

290.
550.

180.
455.

300.

6.
25.

1.4

2.5

2.0

3.0

37.

460.

13.

Plants, commer-
cial. (Hops, to-
bacco, etc.)

0.8

T.7

3.3
9.0

t

0
4.8

3.4

0.7
8.8

t

55.

48

2.0

7.1

672.

Plants, legume ;
seeds.

0
2.3

5.2
8.1

0

tr.

0
2.5

0.2
0.6

t

200.
350.

37.

145.

270.
600.

12.
76.

1.3

8.0

2.4

0.5

250.

97.

400.

32.

Plants, legume ;
straw.

0.1

2.8

2.7
6.1

t

0.7
2.2

2.7

8.1

5.

IS.

48.
100.

250.
530.

170.
400.

10.
50.

2.0

3.8

1.5

4.5

9.

80.

390.

300.

18,

Potatoes; tubers.

0.3
0.6

1.6
2.0

1

0.2
0.94

0.9

t

0.8
3.0

5.
40.

3.
27.

120.
160.

0.5
8.0

0.45

1.7

2.0

18.

10.

190.

3.0

Potatoes; tops.

O.G
0.9

0.6
1.0

0.78

0.5
0.0

0.4
0.7

+

t

t

t

0.75

0.8

0.55

0.55

5.5

Koot-crops :
roots.

0.3
1.1

0.5
1.4

0.12
3.6

0

4.4

0.1
2.5

t

5.
26.

I

23.
155.

0.8
8.0

0.0

1.0

0.67

3.9

0.33

11.

12.

85.

1.0

Koot-crops ;
tops.

1.1
3.0

0.8

2.0

^

0.5
1.4

0.3
10.

8.

12.
38.

9.
34.

21.
129.

3.
10.

1.7

1.5

0.6

26.

25.

60.

6.

Salt.

1.4
10.6

0

tr.

0.5
3.7

1.9

6.0

Saltpetre
(Chili).

371.

020.

10.

596.

8.0

170

* Sugar.— t Present.—^ Possibly present.

296

TABLES.

TABLE

X.— [Continued.

i4

d

d

i

i

i

i

%

^

i

1

(t)

Soils.

920.
990.

tr.

28.

tr.
20.7

0.0023
0.102

tr.
170.

tr.
14.0

8
140.

15. -
110.

t

950.

4.0

2.0

0.04a5

5.0

3.0

50. _

30.

Sugar-beet.

800.
900.

3.
6.

2.5
3.5

0.15
0.3

0.4
0.9

1

0.4
0.7

0.5

0.16
0.21

0.1
0.2

815.

5.

3.0

0.2

0.7

0.2

0.12

0.1

Supetphos-
phate.

94.
223.

155.

576.

728.

065.

1

*!

159.
325.

230.

0

0
3.0

'

1.0

(3)
Urine.
Herbivora.

S(50.
925

17.
47.

6.0
20.

2.0
5.0

t

0.31
0.16

875.

SO.

13.

3.0

4.2

U,.,„e. '''
Man.

934.
970.

10.3
14.5

1.7
5.0

1.0
3.0

3.6
8.0

0
0.9

0
0.33

0
0.23

948.

13.5

2.5

2.0

6.0

0.26

0.2

Water, rain.

0

tr.

0
tr.

0.0001
0.004

0
tr.

0
tr.

J
tr.

J

tr.

).0014

(5)
Water, river.

0
0.013

9
0.024

0.00009
0.005

0.007
0.1

0.002
0.032

0
0.007

0
0.012

0.001
0.013

3.001

0.061

0.01

0.006

(6)
Water, spring.

0
0.41

0
0.58

0
0.0006

0.002
0.23

0
0.104

)
0.0128

)

J. 0045

0*
0.14

0.02

traces to 17 ; average 0.8. SiOj and
-(2) FC2O3, usually traces. Sand and
iblc p2<^5 i'l older and fo

t Present. — 1 Possibly present. — (1) Mn,
insoluble silicates 240 — 930; average 770.-

insoluble silicates 29—178 ; average 48. Soluble P2O5 in older and foreign phos-
phates, 120; in recent American. &3. Chlorine, usually 0.— (3) ITippuric acid
1.8—60. Urea, 18—70; average 28.— (4) Urea. 23—33; average 29. Uric acid,
0.5-1.1; average 1.— (5) Mn. 0—0.003.— (6) AI2O3, NH3, FcaO,, P2O,, and N,0,
usually 0. MgO, K^O, Na^O, SO3, CO2, and CI, rarely 0. Organic matter 0-0.07 ;
average 0.03.

TABLES.

297

TABLE X.—iConiinued.

O

02

8'

02

o

^

i4

3i mU

i

Soils.

O.OT
11.0

O.OOli 0.001
5.00 0.12

0
220.

0
14.

0.5
50.

1.5

1.0 1 0.03

5.

0.3

2.

Sugar-beet.

O.IS
0.28

0.37
1.0

0.3

1.7

t

t

t

6.

28.

10.
34.

66.
138.

*

6.
9.

0.2

0.7

1.0

0.1

8.

13.

100.

8.

Superphosphate.

121.
314.

12«.
233.

0
59.

r

210.

170.

20.

Urine.
Herbivora.

0
l.G

8.7
14.0

10.8

0
3.3

4.4
26.

15.

Uriue.
Man.

0.4

3.7

1.7
3.0

2.0
5.0

7.
18.

1.5

2.0

3.6.

14.5

Water, raiu.

0
tr.

0.
tr.

0.0001
O.OOG

O.OOOo

Water, river.

0.002
0.0T9

0.022

0.001
0.01

0.0017
0.08

0.046

0
0.089.

0.01

Water, spring.

0
0.5

0
0.006

3
0.67

0
0.970

0
0.560

0.2

* Sugar.— t Present.

INDEX,

Acetic acid, as reagent, 8 — estima-
tion, 101— in vinegar, 2G8— oc-
currence of, 145— reactions 101

Acetometer 24

Acids, free, in wine 280

Albumen, llT-in millc 2G3

Albuminoids, see protein com-
pounds.
Alcohol as reajjent, 10 — estimation,

12G— in wine 270

Alcoholometer 24

Alkalies, elimination by milk of
lime, 157- by oxalic acid, 158 —
estimation as chlorides, 53, 157
—as sulphates, 53— in gypsum,
238- in limestone, 209— in marl,

207— in wine 283

Alumina, hydrated, in soil 180

Aluminium, elimination of, 153 — es-
timation of, G6— reactions G5

Ammonia, estimation of by distilla-
tion with sodic hydrate and ti-
tration, 57— by distillation and
Nessler's solution, 58— platinic
cliloride, 55— Schlossing's proc-
ess, 56— in beets, 260- in fodder,
aqueous extract of, 254 — in gua-
no, 232 — in manure of the
farm-yard, 214— in soil, 1^— in
Buperphosphatc, 235 — in urine,

219— in water 272

Ammonia, reactions of. 54

Amnionic acetate as i*eagent, car-
bonate chloride, fluoride, 10 —
hydrate molybdatc, nitrate, oxa-
late, sulpliate, sulphide, 11—

tartrate 12

Ammonio-ferrous sulphate, as re-
agent 12

Ammonium, see ammonia.

Analyses, calculation of 42

Analysis, qualitative, course of for
acids, 130— for bases, 130— table

for ....144

\

Analysis, quanlitativc, schemes for,
IGl — special methods for separa-
tion in 146

Animal substances, ash of 248

Aqua regia, as reagent '8

Argentic nitrate as reagent, 12—
standard solution of 95

Arsenic, occurrence of, 145 — reac-
tions 73

Artichokes 262

Ash analysis, preparation of asli
for, 241— statement of results. . .247

Ash, elimination of carbon and car-
bonic acid in 150

Ash of animal substances, 248— of
bone-black, 230— of bone-meal,
228— of coal, 243— of flour, 262—
of fodder, aqueous extract, 253
—of green fodder, 251— of fuel,
249— of guano, 232— of manure
of the farm-yard, 213, 21G— of
milk, 263 — of peat, 243 — of
plants, 241— of seeds, 2G2— of
superphosphate, 235, 236 — of
urine, 218, 219— of wine, 278— of
wool , 270

Asli of plants, carbonic acid, clilo-
rine, 243 — coal, sand and silica, 243

Ash of plants, Ileichhardt's method
of preparing, for estimation of
sulphur and chlorine 24G

Ash rich in carbonates, 243 — rich in
silica 244

Ash, sulphur in 246

Aslies of fuel, carbonic acid, chlo-
rine in, complete analysis of,
potassa in 249

Baker guano 234

Baric acetate as reagent, chloride
hydrate, nitrate ^ . . . 13

Barium, occurrence of, 145— reac-
tions 59

Barlv, tanner's, tannic acid,Avater in, 270

Beets (and turnips), ammonia In,

INDBX.

299

258— ash of, 258— crude cellulose
in, fat, 258— nitric acid 260— ni-
trogen, pectose, 258— starch 200
—sugar, 258— water 257

Bone-ash 231

Bone-black, ash of, 230 — calcic hy-
drate in, carbonic acid, chlo-
rine, nitrogen, phosphoric acid,
etc., water 230

Bone-meal, ash of, 228, 229— fat in,
fineness of division, gelatine in,
229— nitrogen, phosphoric acid,
water 228

Bunsen's method of filtration 33

Butter (and cheese), casein in, fat,
267— salt, 208— water 267

Butter in milk, estimation of, 204,
266 — by Vogel's optical milk-
test •:65

Calcic chloride as reagent, hydrate,
fluoride, sulphate 14

Calcic hydrate in bone-black 230

Calcium, elimination of, 157— esti-
mation of as carbonate by igni-
tion of oxalate, 60— as lime by
ignition of oxalate, 61 — as oxa-
late by titration of oxalic acid,
Gl — as oxalate in presence of
phosphoric acid, 62— as sulphate
by conversion of oxalate into
sulphate, 62 — reactions, 60 —
separation from magnesium 04

Calculation of analyses 42

Carbon eliminated from residue left
after incineration, 150— in urine. 223

Carbonic acid, estimation of, 79—
by Fresenius's apparatus, 81 —
in ash left in the determination
of volatile matter, 150 — in ash
of plants, 24:3, 244— in ashes of
fuel, 249— in bone-black, 230—
in gypsum, 238— in manure of
the farm-yard, 213,215 — in marl,
206— in soils, 173— in urine, 218
— reactions of, 79 — separation
from chlorine 83

Casein, 118 — in butter and cheese,
267— in milk 263, 266

Cellulose, lOS — in excrements of
animals, 223— in fodder, 252, 250
—in seeds, etc., 262 — in roots,
258 — reactions 108

Cement, hydraulic, analysis and

testing of 211

Cheese, (see also batter) 207

Chili saltpetre, adulterations detect-
ed, 240 — complete analysis of,
239— nitric acid in, 240— potash,

soda, water in 239

Chlorine, estimation of by gravime-
tric process, 94— by volumetric
process, 95— in ash of fuel, 249
—in ash of plants, 243, 244--in
bone-black, 230 — in farm-yard
manure, 215 — in organic combi-
nation, 152 — in the plant, 245 —
in soil, 186— in urine, 220— reac-
tions of, 94 — separation from

carbonic acid 83

Citric acid, as reagent, 8 — occur-
rence of, 145~reactions 103

Clark'%^ method of determining

hardness of water 274

Clay 212

Coal (carbon) in ash of plants 243

Coal ashes 250

Cohaltic nitrate as reagent 15

Cochineal as reagent 15

Copper, occurrence, 145 — reactions. 73
Coprolites, complete analysis of—

phosphoric acid in 231

Cupric acetate as reagent, sulphate, 15

Curcuma-paper 15

Cyanogen, occurrence, 146— reac-
tions 97

Desiccator, the 40

Desiccation of substances 147

Division of solutions in quantita-
tive analysis 40

Dragendortf' s process for estimat-
ing starch Ill

Dung of animals 223

Ether, as reagent 15

Evaporation, 27— of solutions con-
taining excess of amnionic salts,
when the residue is to be ignit-
ed 28

Excrements, solid • 223

Fat, 125— in beets, 258— in bone-
meal, 229 — in butter, 267 — in
flour, 262— in fodder, 252— in

milk, 264— in seeds 262

Fehling's solution 113

Ferric chloride as reagent, 15— ni-

BOO

INDEX.

trate, oxide 15

Ferric oxide, elimination, 153 — esti-
mation, GT — hydrated, with
aluminic hydrate in soil, 18G —
and other substances in farm-
yard manure, 21G— reactions, 6G
-—separation from phosphoric

acid 153

Ferrocyanogen, occurrence, 14G —

reactions 98

Ferrous chloride as reagent, IG—

sulphide IG

Ferrous oxide in soil, estimation,

187— reactions 66

Fertilizers, 213 — commercial, tariff

of prices for valuation of 226

Fiber, see cellulose.

Fibrine 118

Filters, incineration of, 38 — wash-
ing of with dilute acid SI

Filtration, 31— byBunseu's process,
33 — by the wash-bottle arrange-
ment 37

Fleck's method of determining

hardness of water 276

Flour, (see also seeds) 262

Fluorine, reactions 09

Fodder, aqueous extract of, estima-
tion, 253— ammonia in, 254— -ash
of, 253— gum, nitric acid in, 255

—nitrogen, 254— sugar 255

Fodder, dried, 251— ash, 251~ccllu-
lose in, fat, protein compounds,

253— starch, 257— water 251

Fodder, green, ash of, water in,
preparation of sample for analy-
sis 251

Gelatine in bone-meal 229

Glucose, estimation, reactions 113

Graduated instruments, testing and

use of 40

Guano, amraoniacal (Peruvian), ash
of, and ammonia in, 232 — com-
plete analysis of, 233 — marks of
a good article, 233— nitrogen in,
232— oxalic acid, 233— phosphor-
ic acid, etc., 232 — solubility in
water, 233— uric acid in, 233—

Avater in 232

Guano, phosphatic (Baker, etc.) 234

Gum, estimation of, 112— in fodder,
aqueous extract of, 255 — in

wine ......279

Gypsum, alkalies in, and carbonic
acid, 238— complete analysis of,
237— solubility in acid, water

in 237

Heat, absorbent power of soil for,
and c<mducting power, 197— re-
taining power 193

Ilippuiic acid, estimation, reac-
tions, separation from iiric, 106

— in urine. , 221

Hops, statement of analysis of ash

of 248

Ilumus in marl, 208— in soil 1'83

Ilydric disodic phosphate as re-
agent , 21

Ilydriodic acid, reactions of 98

Hydrochloric acid as reagent, 8— es-
timation, sec chlorine — reac-
tions 94

Hydrocyanic acid 97

Hydroferrocyanic acid 98

Hydrofluoric acid 99

Hydrogen as reagent, 16— in urine, 223
Hydrosulphuric acid as reagent, 8—
estimation, sec sulphur— reac-
tions 98

Hygroscopic moisture, estimation.. 147
Ignition of precipitates, 38 — of resi-
dues containing excess of am-
nionic salts 28

Incineration of filters, SB—to deter-
mine organic matter 149

Indigo solution as reagent 16

Iodine as reagent, 16 — occurrence,

146— reactions 98

Iron (see also ferric oxide), estima-
tion by precipitation, 67 — by
volumetric process with potas-
sic permanganate, G7— by volu-
metric process witli sodic hypo-
sulphite, 70 — reactions, 06 —
separation from alumina and

phosphoric acid 153

Iron turnings as reagent, 16 — wire.. 16
Lactic acid, estimation, 105 — occur-
rence, 145 — reactions 104

Lactometer 24

Lacto-protein in milk 266

Lactose, 117— in milk 260

Lead, occurrence, 146 — reactions..-. 72
Lead-paper as reagent 16

INDEX.

501

Levigation 2G

Lovulose 115

Lime, burned 2C9

Lime in marl, 20G— in water, 27:3 —
reactions and estimation, see

calcium

Limestone, 209— alkalies in, 209—
value for mortar lime, 210— for

hydraulic cement 211

Litmus-paper, blue and red IG.

Maijnesia (calcined) as reagent, 17

—magnesia mixture 17

Magnesium, elimination from mix-
ture of metals, etc., 157 — esti-
mation as pyrophosphate, GS—
reactions, G2— separation from
calcium as pyrophosphate, 04 —

by sulphuric acid G5

Malic acid, estimation, 104 — in
wine, 282 — occurrence, 145— rc-

aclions 104

Malt, as reagent 17

Manganese, elimination from mix-
ture of substances, 150 — estima-
tion, 71— occurrence, 146— reac-
tions 71

Manganic binoxide as reagent 17

Manures, commercial, general con-
siderations, 224 — nitrogen in,
225— phosphoric acid, 224— po-
tassa, 225 — statement of analy-
sis, illustrated, 225 — tariff of

prices for valuation of. 22G

Manure of the farm-yard, 213— am-
monia in, 214 — aqueous extract
of, 214 — ash, carbonic acid, 213
—insoluble part, 214, 210— nitro-
gen, organic matter, 213— state-
ment of analysis, illustrated,
217 — sulphur, sulphuric acid in,

214— Avatcr 213

Marl, alkalies in, 207 — carbonic
acid, 20G — humus, 208— lime and
magnesia, 207 — nitrogen, 208 —
phosphoric acid, 207— silt analy-
sis of, 205— water 200

Marl, burned 208

Meal (see also seeds) 2G2

Measurement of solutions 40

Mercuric nitrate as reagent, 17 —

standard solution of 122

Mercurous nitrate as reagent 17

Milk, albumen in, ash, casein, 263 —
fat, 264, 265— lacto-protcin, etc.,
266— pi-otein compounds, 2G3—
sugar (lactose) 2GG— VogeFs op-
tical test, 265— water 203

Milk of lime as reagent 17

Nesslcr's solution as reagent, 55 —

estimation of ammonia witli. .. 58
Nitric acid as reagent, 8 — estima-
tion of by fusion of nitrate with
silica, 92— by insolubility of am-
nionic nitrate in alcohol, 93 —
by Schlussing's process, 89— in
beets 260— in Chili saltpetre,
240— in farm-j-ard manure, 215—
in fodder aqueous extract, 255—

in soil 185

Nitric acid, reactions 88

Nitrogen in beets, 258 — in bone-
black, 230— in bone-meal, 228 —
in commercial manures, 225 —
in fodder, 252, 254— in guano,
232 — in manure of the farm-
yard, 213,215, 216— in marl, 208—
in soil, 173— in superphosphate,

235— in urine 219

Nitro-hydrochloric acid, sec aqua

regia

Nitrous acid in water 273

Organic matter, estimation by igni-
tion in muffle, 149— ignition in
platinum dish, 149— by titration
with potassic permanganate,
151— in manure of the farm-yard,
213, 215— in soil, 183— in urine,

218— in water 272

Oxalic acid as reagent, 9— estima-
tion by conversion into carbon-
ic acid, 101— by titration with
potassic permanganate, 100 — in
guano, 233— reactions of, 99—

standard solution of 50

Oxygen, preparation of 17

Pea, as fodder plant, statement of

analysis of 257

Peat ashes 250

Pectose in beets 258

Peruvian guano 232

Phosphate, see superphosphate

Phosphatic guano 234

Phosphoric acid, 83— elimination by
ammonic molybdate, 85, 157— by

302

INDEX.

ferric chloride, Bodic acetate,
magnesia mixture, and citric
acid, 159— by metallic tin, 155—
in presence of large excess of
ferric oxide, 100— when it alone
is to he estimated, 159 — estima-
tion as magnesic pyrophosphate
84 — by volumetric process,
86— in hone-black, 230— in bone-
meal, 22S — in commercial ma-
nures, 224— in coprolites, 231 —
in guano, 232— in marl, 207— in
phosphorite, 231— in superphos-
phate, insoluble, 236— soluble,

235— in urine . .222

Phosphoric acid, reactions of, 83

Phosphorite, complete analysis of,

231— phosphoric acid in 231

Phosphorus salt, as reagent 18

Piknometcr 23

Plant ash, see ash of plants

Plant, chlorine in, 245, 246— sulphur-
ic acid (ready formed), 245— to-
tal snl phur 245, 246

Platinum crucibles, care of. 40

Platinic chloride, as reagent , 18

Plumbic acetate, as reagent, binox-

ide, oxide 18

Potash compounds, commercial 239

Potassic acetate as reagent, 18— bi-
sulphate, chromate, chlorate,
dichromate, fcrricyanidc, ferro-
cyanide, hydrate, iodide, per-
manganate, 19— and sodic car-
bonate, and sodic tartrate,

sulphocyanate 20

Potassium, elimination from mix-
ture of metals by milk of lime,
157 — by oxalic acid, 158 — by
platinic chloride, 159— from sili-
cates, 76 — estimation as chlor-
ide, 45 — as potassic platinic
chloride, 46— sulphate, 46— by
titration with standard acid, 47
—in ashes of fuel, 249— in Chili
saltpetre, 239 — in commercial

manures, 235— -in water 272

Potassium, reactions, 44— separa-
tion from sodium by indirect
determination as chloride, 53 —
as sulphate, 53 — by platinic
chloride . . 52

Potassium and sodium, conversion
of mixed sulphates into chlor-
ides 53

Potatoes, dry substance in, soluble
in water, protein compounds in,

261— starch, 262— water 261

Precipitation 29

Precipitates, ignition of, Avith Alter,
38— after separation from filter,
38— transferring of to filter, 30—

washing of, 32— weighing of 38

Protein compounds, estimation of,
118— in fodder, 252— in milk, 263 ^
— in potatoes, 261— in seeds, 262

— in wine, 278 — reactions of 117

Qualitative analysis, course of 130

Quantitative analysis, schemes of...J61

Quartz powdered, as reagent 20

Residues, ignition and weighing of, 38
Eesults of analyses, calculation of. . 42
Rocks, and products of their weath-
ering 205

Saccharose, estimation, 110— reac-
tions 115

Saccharometer 24

Salt, complete analysis of, 238— esti-
mation of in butter and cheese.. 268
Saltpetre, Chili, see Chili saltpetre.
Sand in ash of plants, 243— in soils,

182— separation of from silica.. 75
Schlossing's process for estimating

ammonia, 50— nitric acid 89

Seeds, ash, etc., dry substance solu-
ble in water, in starch, water.. .262

Silica and sand in ashes 243

Silicates, fusion of with sodic and
potassic carbonate, 76 — solution
of, 74 -treatment of with amnio-
nic fluoride, 77— with hydroflu-
oric acid 77

Silicic acid, estimations and reac-
tions, 74— separation of from

coal and from sand 75

Silt analysis of marl, 205— of soils,
Dietrich's method, 172— Nobel's

method 169

Silver refuse, to work over 13

Skin, powder of. as reagent 118

Soda-lime as reagent 20

Soda, standard solution of 50

Sodic acetate as reagent, 20— sodic
and amnionic phosphate, 20— hi-

INDEX.

;o3

Bulpliitc, carbonate, hyposul-
phite phosphate, nitrate 21

Sodium, elimination of from sili-
cates, 76— elimination with milk
of lime, 157 — with oxalic acid,
15S — estimation of as chloride,
or as sulphate, 52— by indirect
processes, 53— in Chili saltpetre, 239

Sodium, reactions, 51 — separation
from potassium by indii'cct meth-
od, as chloride or as sulphate, 53
—by platinic chloride 52

Sodium, sulphate of converted into
chloride 53

Soil, absolute weight of, 19S— ab-
sorptive power of for salts, 188 —
adhesive poAver of 200

Soil analysis, experiments to be
combined with, 200 — general
considerations in regard to, 105
—preparation of sample for 16G

Soil analysis, chemical part^ prepa-
ration of soluti(ms for, 174 —
with carbonated water, 177—
with cold hydrochloric acid, 174
— with hot hydrochloric acid,
179 — with hydrofluoric acid, 181
— with phosphoric acid, 182—
with sulphuric acid 180

Soil analysis, mechanical part, 168—
silt process by Dietrich's meth-
od, 172— by NObel's method, 109

Soil analysis, physical part, in rela-
tion to heat-absorbing power,
19T— to heat-conducting power,
197 — to heat-retaining power, 198
— consistency, 199— power of ab-
sorbing water-vapor, 192 — of
retaining liquid water, 193 — of
retaining water-vapor, 192— rate
of evaporation of water from,
194 — readiness with which
water moves downward in, 197
— readiness with which water
moves upward, 196 — readiness
with which water percolates
through,196 — volume when com-
pletely saturated with Avater, 199
—porosity, 199— specific gravity,
apparent and real, 198— tenacity,199

Soil analysis, statement of results
illustrated 188

Soil, estimation of ammonia in, 188
—of carbonic acid, 173— chlo-
rine, 186— ferrous oxide, 187 —
hydrated alumina and ferric ox-
jdc, 186- humus, 183— nitrogen,
total in, 173 — nitric acid, 185 —
organic matter, 183 — sand, by
phosphoric acid, 182 — sulphur,
186— water 173

Solution 25

Solutions, division and measure-
ment of 40

Solutions standard, preparations of,
48, 55, 67, 70, 86, 95, 100, 113, 122,
151,266 274

Solutions, estimation of solid mat-
ter in by simple evaporation on
water-bath, 148 — after mixture
with gypsum, 149— by evapora-
tion in vaccuo on hot sand, 148
— to save ammonia that may be
given off 148

Specific gravity of liquids, with the
areometer,23— with the piknomc-
ter or specific-gravity bottle, 23 —
- of soil apparent and real, 198—
of solids by specific gravity of
liquid of the same density, 25 —
if soluble in water, 25— by vol-
ume of water displaced, 24— by
iveight of water displaced in
piknometer, 24— of urine, 217—
of wine, 278— of wool 270

Starch, 109- estimation by conver-
sion into sugar by malt, 109— by
sulphuric acid, 110 — Dragen-
dorfl's process,lll— in beets, 260
—in fodder, 257— in potatoes,
262— in seeds, 262— reactions of,109

Starch paper 21

Sugar (see also saccharose, glucose,
etc.) estimation in beets, 258 —
in fodder, aqueous extract, 255
—milk. 266, 267— in wine .279

Sulphur, estimation in organic com-
bination, 152— in manure of the
farm-yard, 214— in plant, total,
245— in soil, 286— in urine, 223—
reactions 98

Sulphuric acid as reagent, 9 — elimi-
nation of, 157— estimation, 78 —
in gypsum, 237— in manure of

304

INDEX.

the farm-yard, 214 — in plant, 245
—in mine, 223— in vinegar, 208
— in wine, 283 — reactions of, 78

— standard solution of 43

Superphosphates, ammonia in 235—
ash, 235 — complete analysis of,
23G — nitrogen in, 235— phosphor-
ic acid, insoluble, 236— soluble,

235— water 234

Tables 2&4

Tanner's bark 270

Tannic acid, as reagent, 10 — estima-
tion, 107— in bark, 270— in -wine,
280— occurrence, 145— reactions. 102
Tin, as reagent, 21 — use to elimi-
nate phosphoric acid 155

Turmeric as reagent 21

Uranic acetate as reagent, 21— stand-

ai'd solution of 78

Urea as reagent, 22— estimation, 122

—in urine, 221— reactions 122

Uric acid, estimation, 105 — in guano.
233— in urine, 221— reactions, 105

—separation from hippnric lOG

Urine, ammonia in, 219— ash of, 218,
219 — carbon in, 223 — carbonic
acid, 218— chlorine, 220— dry sub-
stance in solution, 218— hippuric
acid, 221— hydrogen, 223— nitro-
gen, 219— phosphoric acid, 222—
sulphur and sulphuric acid, 223
—urea, 220— uric acid, 221—

specific gravity of 217

Valuation of manures 220

Vinegar, acetic acid in, 268 — free

sulphuric acid 268

VogcFs optical milk test 265

Washing bottle 33

Water distilled as reagent 22

Water, hygroscopic, estimation of
by simple desiccation on the
water-bath, 147 — estimation
when ammonia is present, 147—

estimation by simple ignition,
147— estimation of in bark, 270
—in beets, 257— in bone-black,
230— bone-meal, 228— butter and
cheese,267— Chili saltpetre, 239—
foddor,251— green parts of plants,
241— gypsum, 237— guano, 232—
marl, 206— milk, 203— potatoes,
261— roots, 241— salt, 238— seeds,
262— soil, 173— superphosphate,
234— wool 270

Water, estimation of ammonia in,
272— of dry substance in solution
in, 271 — of hardness, Clark's
method, 274— hardness byFleck's
method, 270 — of lime in, 273— of
nitric acid, 272— of nitrous acid,
273— organic matter, 272 — the
same by titration with potassic
permanganate, 151 — potassa in.. 272

Water, expulsion of from solutions,
sec evaporation — relation of to
soil in liquid form, 193— as va-
por 192

Wine, alcohol in, 279— alkalies in,
283 — ash of, 278 — average com-
position of, 283 — dry substance
in solution, 278— free acids in,
280— gum and sugar, 279— malic
acid, 282— protein compounds,
278— specific gravity of, 278—
sugar, 279 — sulphuric acid free,
283— tannic acid, 280 — tartaric
acid 282

Wolffs process for converting starch
into sugar Ill

Wool, estimation of ash of, 270— of
effect of washing at the factory,
270— water in, 270— preparation
of sample for examination 269

Zinc as reagent, 22 — occurrence,
146— reactions 72

ADDENDA

FKOM PERIODICALS RECEIVED WHILE THE FOREGOING
MATTER WAS IN PRESS.

Bunsen's filtration process; paj^e 33. R. S. Dale {Chem. News,
Mig., Ed. 20, 108) states, that more rapid filtration can be obtained by
substituting- platinum- wire gauze, for the foil in the funnel, without any
more danger of tearing tlie paper; and tlie gauze funnel can be fitted in
the glass one with sufficient accuracy, by means of a cone of wood turn-
ed to the proper angle. Undoubtedly, this gauze funnel can be advan-
tageously used in cases wheie the pressure on the liquid in tlie filter is
much less than an atmosphere, as when the rarefaction of the air in the
filtering flaslc is efi'ected by means of the flow of water from one bottle
to another.

Standard acid and alkaline solutions ; page 48. Dr. Fleischer
{Chem. News ; Am. Bepr., 5, 88) gives some good reasons for preferring
a standard hydrochloric acid, instead of sulphuric; it forms soluble
salts with all the alkaline earths, is readily obtained pure, is estimable
with great accuracy by a standard solution of argentic nitrate as well as
by an alkali, and its constancy is unimpeachable. The standard of the
acid can be determined by means of a weighed amount of pure calcic
carbonate, that has been slightly heated, or by the standard argentic so-
lution.

For a standard alkaline solution, ammonia has many advantages over
soda; it is more easily obtained pure, and has so slight a tendency to
absorb carbonic acid from the air, that no special provision need be made
against it.

As some neutral amnionic salts have a slight acid reaction when the
solution is liot, the liquid to be tested should be cold. A solution con-
taining half an equivalent of ammonia in the litre, is recommended.

Both of these standard solutions should be kept in a cool place, free
from dust. If the aininonic solution is exposed to hot summer weather,
the bottle containing it should be placed in cold water that is renewed
every day; by exposure to a temperature above 25° C, the standard of
the solution will be very slightly altered.

Estimation of iron by the permanganate process ; page 07. M.
Moyaux {Revue Universelle des Mines, etc., Chem. News, Am,. Repr., 5, 179)
states, that the useof ammonio-ferrous sulphate to determine the staud-
305

306 ADDENDA.

ard of the peimanganic solution is unsafe, for the reason that the com-
position of the salt is not constant, and that, consequently, metallic iron
or oxalic acid must be used. Fresenius also, gives the preference to the
use of metallic iron as the most accurate, although perhaps less conven-
ient, method; he gives the following directions for executing the proc-
ess. Weigh out about 0.2 grm. of the finest piano-forte v^ire, free from
rust, and add to it in the long-necked flask (p. 68) 20 c.c. of dilute sul-
phuric acid, and as much water, and proceed with the solution in the
current of carbonic acid, and the subsequent titration, as directed in tlie
case of the use of the ammonio-ferrous sulphate. Instead of £,

7
in the proportion on page 69, substitute F x 0.997 ; this product is taken
as the weight of pure iron in the weight F of iron used, since the purest
wire contains about 0.3o|o of impurities!

In the text (pp. 69, 154) the preference is gfven to a sulphuric-acid so-
lution of the ferrous salt for titration rather than a solution in hydro-
chloric acid. In an appendix to his Quantitative Analyse^ Fresenius states,
that the titration of a hydrochloric-acid solution is unreliable unless con-
ducted as follows. Make the volume of the solution up to a quarter of
a litre, add 50 c.c. of this solution to a considerable quantity of water
acidified with sulphuric acid, titrate this mixture with permanganate,
add to it 50 c.c. more of the ferrous solution, titrate again, and so on
with a third and fourth portion of the same solution; finally use the
last two results, the mean of which multiplied by five will give the
amount of permanganic solution that should be required for the whole
amount of the ferrous solution.

The precipitate op ammonio-magnesic phosphate, in the esti-
mation OP MAGNESIUM, PAGE 64, AND OF PHOSPHORIC ACID, PAGE 87.

As the results of experiments by Kubel and by Kiesel {Fres. Zeitschrift
8, pp. 125, 164), it appears that the solubility of this precipitate in the
liquid in which the precipitation takes place, in the presence of con-
siderable amnionic chloride and a not too great excess of magnesic sul-
phate, is very nearly compensated for by the minute quantity of basic
magnesic sulphate, or of magnesia, that is precipitated at the same time;
hence the correction for the imperfect insolubility of the precipitated
phosphate seems to be unnecessary.

Organic matter in water, page 273. R. Angus Smith, who is a
strong and earnest champion for the permanganate process, in the ex-
amination of water with respect to the presence of hurtful organic
matter, uses a stronger solution than Kubel (see page 151). He adds 2
grms. of the salt to a litre of water, and gives the following directions
for the titration :

To not less than a litre of the water add a drop of this permanganate
solution ; stir the liquid well, and wait until the color disappears, and
proceed in this manner as long as the color disappears quickly, say in a
minute or two ; generally, considerable permanency of color is obtained

ADDENDA. 307

in 10-15 minutes. Then add 3 "rms. of sulphuric acid to the liquid and
proceed to add more permanganate in the same manner as before.

According to Dr. Smith, the oxygen of tlie permanganate used hefoi'e
adding the acid, was taken up by products of putrefaction in solution in
tlie water, such as sulphuretted hydrogen, and that required after the
addition of the acid, was consumed by easily oxidizable organic (animal)
matter; all matters that thus act speedily on the permanganate are the
most harmful in a sanitary point of view.

. According to this writer and to W. A. Miller also, the results obtained
can be expressed more accurately, by giving instead of the number of
cubic centimetres of permanganic solution used, the amount of availa-
ble oxygen therein — of which each cubic centimetre contains 0.005
grm.

Dr. Smith estimates the nitrous acid in the water roughly, by di-
luting a measured quantity of it until iodized starch i)aper (paper
dipped in a solution of potassic iodide containing a little starch) is
no longer colored blue by it, even after a contact of several minutes;
this diluted solution then contains about one part of nitrous acid in
100,000 of water, and upon this basis the proportion in the water
before dilution can be estimated. {Chem. News Am. Repr. 5.141, Eny.
Ed. 20.113).

VALUABLE AND BEAUTIFUL WORK.

HARRIS'

Insects Injurious to Yegetation.

BY THE LATE

THADDEUS WILLIAM HARRIS, M.D.

A New Edition, enlarged and Improved, with additions from the anthor'i ^
manuscripts and original notes.
Illustrated by engravings drawn from nature under the supervision of

PKOF^ESSOR. J^GJ-ASSIZ.

Edited by CHARLES L. FLINT,
Secretary of the Massachusetts State Board of Agriculture.

O OnSTTEJ IsTTS.
CHAPTER I.

INTRODUCTION.— Insects Defined—Brain and Nerves— Air-Pipes and Breath-
ing-Holes—Heart and Blood— Metamorphoses or Transformations—
Classification : Orders and Groups.

CHAPTER II.

COLEOPTERA.— Beetles— Scarabasians—Gi-ound-Beetles— Tree-Beetles— Cock-
chafers—Flower, Stag, Spring, Timber, Capricorn, Leaf-mining, and Tor-
toise Beetles— Chrysomelians—Cantharides. ,

CHAPTER III.

ORTHOPTERA.— Earwigs — Cockroaches- - Soothsayers — Walking-sticks or
Spectres— Mole, Field, Climbing, and Wingless Crickets— Grasshoppers-
Katydid— Locusts.

CHAPTER IV.

HEMI PTERA.— Bugs— Squash-Bug—Clinch-Bug— Plant Bugs— Harvest Flies—
Tree-Hoppers— Vine-Hoppers— Plant-Lice— American Blight— Bark-Lice.

CHAPTER V.

LEPIOOPTERA.— Caterpillars — Butterflies — Skippers — Hawk-Moths— ^ge-
rians or Boring Caterpillars— Moths— Cut-Worms— Span- Worms— Leaf-
Rollers— Fruit, Bee, Corn, Clothes, and Feather-Winged Moths.

CHAPTER VI.

HYMENOPTERA— Stingers and Piercers— Saw-Flies and Slugs-Elm, Fir,
and Vine Saw-Fly — Rose-Bush and Pear-Tree Slugs— Horn-Tailed
Wood-Wasps— Gall-Flies— Barley Insect and Joint Worm.

CHAPTER VII.

DIPTERA.- Gnats and Flies— Maggots and their Transformations— Gail
Gnats— Hessian, Wheat, and Radish Flies— Two- Winged Gall-Flies, an^
Fruit-Flies.
APPENDIX.— The Army Worm.

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HOW CROPS GROW.

On tlie Cliemical Compsitioii, Strnctnre, ana Life of the Plant,

FOR ALL STUDENTS OF AGRICULTURE.

WITH NUMEROUS ILLUSTRATIONS AND TABLES OF ANALYSES.

BY

SAMUEL, W, JOH^VSON, M.A.,

PROFESSOR OF ANALYTICAL AND AGRICULTURAL CHEMISTRY IN YALE COLLEGE ;

CUEMIST TO THE CONNECTICUT STATE AGRICULTURAL SOCIETY ;

MEMBER OF THE NATIONAL ACADEMY OF SCIENCES.

Tliis is a volume of nearly 400 pages, in whicli Agricultural
Plants, or " Crops," are considered from three distinct, yet closely
related, stand-points, as indicated by the descriptive title.

THE CHEMICAL COMPOSITIOX OF THE PLVXT.

lat— The Volatile Part.

2d. — The Ash — Its Ingredients ; their Distribution, Variation, and
Quantities. The Composition of the Ash of various Farm
Crops, with full Tables ; and the Functions of the Ash.

3d. — Composition of the Plant in various Stages of Growth, and the
Relations subsisting among the Ingredients.

THE STRUCTURE OF THE PLANT AND THE OFFICES
OF ITS ORGANS.

The Primary Elements of Organic Structure.

TJie Vegetative Organs — Root, Stem, and Leaf, and their Func-
tions ; and

The Beproductive Organs, nam,ely, Flowers and Fruit, and the
Vitality of Seeds with their Influence on the Plants they produce.

THE LIFE OF THE PLANT.

Germination, and the conditions most favorable and unfavor-
able to it.

The Food of the Plant when independent of the Seed.

Sap and its Motions, etc., etc.

The Appendix, which consists of twelve Tables exhibitincr
the Composition of a great number of Plants viewed from many
different stand-points, will be found of inestimable value to practi
cal afifriculturists, students, and theorists.

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Principles of their Construction and Use :

WITH

SIMPLE AND PKAOTIOAL EXPLANATIOITS

OF THE

LAWS OF MOTION AND FORC£,

AS APPLIED ON THE FARM.
With 287 Illustrations,

By JOHISr J. THOMAS.

— ♦ — •

CONTENTS.

PART I.— MECHANICS.

Chapter I.— Txtrodtjction. — Value of Farm Machinery— Importance of a
Knowledjje of Mechanical Principles.

Chapter II.— General Principles of Mechanics.

Chapter III.— Attraction,

Chapter IV.— Simple Machines, or Mechanical Powers.

Chapter V. — Application of Mechanical Principles in the Structure of Im-
plements and Machines,

Chapter VI. —Friction.

Chapter VII. — Principles of Draught.

Chapter VIII. — Application of Labor.

Chapter IX.— Models of Machines.

Chapter X.— Construction and Use of Farm Implements and Machines —
Implements of Tillage, Pulverizers.

Chapter XI.— Sowing Machines.

Chapter XII.— Machines for Haying and Harvesting.

Chapter XIII. —Thrashing, Grinding, and Preparing Products.

PART II.— MACHINERY IN CONNECTION WITH WATER.
Chapter I.— Hydrostatics. ^

Chapter II. — Hydraulics.

PART III.— MACHINERY IN CONNECTION WITH AIR.
Chapter I.— Pressure of Air.
Chapter II. — Motion of Air.

PART IV.— HEAT.
Chapter I.— Conducting Power— Expansion, Great Force of— Experiments
with— Steam Engine— do. for Farms— Steam Plows— Latent Heat-
Green and Dry Wood.
Chapter II.— Radiation.

APPENDIX.
Apparatus for Experiments.
Discharge of Water through Pipes.
Velocity of Water in Pipes.
Rule for Discharge of Water.
Velocity of Water in Tile Drains.
Glossary.

JPrice, Post-paid, $1.50.

ORANGE JUDD & CO.,

245 Broadway, Xew-York.

DOWNING'S

FRUITS AND FRUIT TREES

BY

A. J. DO^^^lSrilSiG-.
Newly Hevised and Greatly Enlarged

BY

CHAl^LES DOWlSriNG^.

Octavo, 1122 pages.

The original work of the late A. J. Downing appeared in 1845. Some
years after it was revised and much enlarged by his brother, Charles Downing,
who has again completed the work of a second revision, Charles Downing is
upon all hands acknowledged as one of our highest pomological authorities.
He writes but seldom, but whatever bears his name is accepted as the judg-
ment of one who is entirtly disinterested, as far as the commercial aspects of
pomology are concerned. The present edition contains the results of many
years' labor and experience, which have been devoted to testing the value of
fruits, and acquiring a knowledge of them that should benefit others.

Recommendation from Hon. MARSHALL P, WILDER, President of the
American Pomological Society.

Boston, October 4, 1869.
Gentlemen : I have received a copy from Mr. Charles Downing of the
second revised edition of " Fruits and Fruit Trees of America.'" It is
the most comprehensive of any similar work— in fact, a complete Ekcyclo-
pedia of American Pomology brought down to the present time.

The original edition by his brother, the late Andrew Jackson Downing,

popular as it ever has been, is made doubly interesting and useful by this

revision, comprising as it does the results of a long life of critical observation.

As a work of reference, it has no equal in this country, and deserves a

place in the library of every pomologist in America.

MARSHALL P. WILDER.

This elegant and valuable work will be an indispensable requisite to every
library, and to all interested in Fruits or Fruit Culture.

Price, prepaid, $7.50.

ORANG-E JUDD & CO.,

245 Broadway, New-TorJc,

NEW AMERICAN FARM BOOK.

ORIGINALLY BT

H

^luLElN,

AUTHOR 03" "diseases O:!' DOMESTIC ANIMALS," AND FORMERLT 3DIT0B OF

THE "AMERICAN AGRICULTURIST.'"

REVISED AND ENLARGED BT

AUTHOR 03' "AMERICAN CATTLE," EDITOR OI!' THU "AMERICAN SUORT-HORN
HERD BOOS," ETC.

C O jNTTEJI^T S:

Introduction. — Tillage Iliisbanclry
— Grazing — Feeding — Breeding —
Planting, etc.

Chapter I. — Soils — Classirication —
Description — Management — Pro-
perties.

Chapter II. — Inorganic Tilanurcs —
Mineral — Stone — Eartli — Phos-
phatic.

Chapter III. — Organic Manures —
Their Composition — Animal— Ve-
getable.

Chapter IV. — ^Irrigation and Drain-
ing.

Chapter V. — Mechanical Divisions
of Soils — Spading — PlOAving— Im-
plements.

Chapter VI. — The Grasses — Clovers
— Meadows — Pastures — Compara-
tive Values of Grasses— Implementa
fjr tlieii' Cultivation.

Chaptjjp. VII.— Grain, and its Culti-
vatiaa — Varieties — Growth — Har-
vesting.

CHAPrEn VIII.— Leguminous Plants
— Tne Pea— Bean — English Field
B3an— Tare or Vetch— Cultivation
—Harvesting.

Chapter IX. — Roots and Esculents-
Varieties— Growth — Cultivation —
Securing the Crops — Uses— Nutri-
tive Eq[uivaleuts ot Different Kinds
of Forage.

Chapter X. — Fruits— Apples— Cider
— Vinegar— Pears— Quinces— Plums
Peaches — Apricots — Nectarines —
Smaller Fraits— Planting— Cultiva-
tion—Gathering— Preserving.

Chapver X[.— Miscellaneous Objects
of Cultivation, aside from the Or-
dinary Farm Crops— Broom-corn-
Flax— Cotton— Hemp-Sugar Cane
Sorghum— Maple Sugar -Tobacco-
Indigo— Madder— Wood— Sumach-
Teasel —Mustard — Hops —Castor
Beau.

Chapter XH.- Aids and Objects of
Agriculture — Rotation of Crops,
and their Effects— Weeds— Restora-

tion of Worn-out Soils — Fertilizing
Barren Lands— Utility of Birds —
Fences — Hedges — Farm Roads —
Shade Trees— Wood Lands-^Time
of Cutting Timber — Tools— Agri-
cultural Education of the Farmer.

Chapter XIII. — Farm Buildings-
House — Barn — Sheds — Cisterns —
Various other Outbuildings— Steam-
ing Apparatus.

Chapter XIV.— Domestic Animals
— Breeding — Anatomy— Respiration
— Consumption of Food.

Chapter XV.— Neat or Homed Cattle
Devons — Herefords — Ayi'eshires —
Galloways — Short -horns — Alder-
neys or Jerseys — Dutch or Ilolsteiu .
— Management from Birth to Milk-
ing, Labor, or Slaughter.

Chapter XVI.— The Dairy- Milk-
Butter — Cheese — Different Kinds-
Manner of Working.

Chapter XVIL — Sheep — Merino —
Saxon — South Down — The Long-
wooled Breeds— Cotswold— Lincoln
— Breeding — Management — Shep-
herd Dogs.

Chapter XVIIT. —The Horse— De-
scription of Different Breeds— Their
Various Uses — Breeding— Manage-
ment.

Chapter XIX. —The Ass— Mule —
Comparative Labor of Working
Animals,

Chapter XX. — Swine — Different
Breeds — Breeding— Rearing — Fat-
tening—Curing Pork and Hams.

Chapter XXI. — Poultry— Hens, or
Barndoor Fowls — Turkey — Pea-
cock—Guinea Hen — Goose — Duck
— Honey Bees.

Chapter XXII. — Diseases of Ani-
mals—What Authority Shall We
Adopt ? — Sheep — Swine — Treat-
ment and Breeding of Horses.

Chapter XXIII.— Conclusion— Gene-
ral I^marks — The Farmer who
Lives by his Occupation— The Ama-
teur Farmer— Sundry Useful Tables.

SENT POST-PAID, PRICE $2.50.

ORANGE JUDD & CO.,

245 Broadway, NeAV-York.

AMERICAN CATTLE;

Their History, Breeding, and Management.

By LEWIS F. ALLEN,

Late President New-York State Agricultural Society, Editor "American
Short-Horn Herd Book," Author " Kural Architecture," etc., etc.

Notices by the Fress.

We consider this the most valuable work that has recently been issued
from the American press. It embraces all branches of the important subject,
and fills a vacancy in our agricultural literature for winch work the author, by
his manv years' experience and observation, was eminently tittcd. . . It
ou-ht to be in the hands of every owner of cattle, and the country, as well as
individuals, would soon be much richer for its teachings.— Joz/ma^ of Agn-
culture, {St. Louis.)

The lar"-e experience of the author in improving the character of Ameri-
can herds adds to the weight of his observations, and has enabled him tx) pro-
duce a work which will at once make good its claims as a standard authorily
on the subject. An excellent feature of this volume is its orderly, methodical
arran-^ement, condensing a great variety of information into a comparatively
smalfcompass, and enabling the reader to find the point on which he is seek-
ing light, without wasting his time in turning over the leaves.— iV. Y. Tribune.
" This will rank among the standard works of the country, and will be con-
sidered indispensable by every breeder of live-stock.— iVac^ica^ Farmer, (^Fhtla.)
We think it is the most complete work upon neat stock that we have
seen, embodying as it does a vast amount of research and careful study and
observation.— Wisconsin Farmer.

His history of cattle in general, and of the individual breeds in particular
which occupies the first one hundred and eighty pages of the volume, is writ-
ten with much of the grace and charm of an Allison or a Macaulay. His de-
scription of the leadinj breeds is illustrated by cuts of a bull, a cow, and a
fat ox, of each race. The next one hundred pages are devoted to the sub-
ject of Breeding. This is followed by chapters on Beef Cattle, Working Oxen,
Milch Cows, Cattle Food, Diseases, etc. The arrangement, illustrations, an-
alytical index, etc., of the work are in the best style of modern book-mak-
ing.— New-England Farmer.

The work is one that has been long needed, as it takes the place of the
foreign books of like nature to which our fimers have been obliged to ref:^r,
and furnishes in a compact and well-arranged volume all they desire upon this
important subject. — Mains Farmer.

Whatever works the stock farmer may already have, he can not afford to
do without this. — Ohio Farmer.

It is one of the best treatises within our knowledge, and contains infor-
mation sound and sensible on every page. — TJie People, {Concord, N. H.)

The object of the work, as stated by the author in his preface, " is not only
to give a historical acccount of the Bovine race, to suggest to our farmers and
cattle-breeders the best methods of their production and management, but to
exalt and ennoble its pursuit to the dignity to which it is cntitlerl in the vari-
ous departments of American agriculture." From the little examination we
have been able to give it, we can not recommend it too \x\g\i\Y.— Canada
Farmer.

Considering that there are some ton million milch cows in the United
States, and nearly a thousand million of dollars invested in cattle, the magni,
tude of this interest demands that the best skilled talent be devoted to the
improvement of the various breeds and the investigation of the best method
of so caring for the animals as to gain the greatest profit from them. This
' volume will give the farmer just the instruction which he wants. — N. T. Inde-
pendent.

Price, post-paid, $2.50.

ORANGE JIJDD & CO.,

245 Broadway, New- York.

THE TIM BUNKER PAPERS ;

Or, YANKEE FARMING.

TIMOTHY BUNKER, Esq..

OF HOOKERTOWN, CT.

With Illustrations by Iloppin*

CONTENTS.

34.

37.

A Stroke of Economy.

Ornamental Trees.

Timothy Bunker, Esq.

View of the Bird Law.

Guano in the Hill.

On Moss Bunkers.

On Subsoiling.

Going to the Fair.

In Tall Clover.

On Horse Racing.

At the Farmers' Club.

On an Old Saw.

Book Farming in Hookertown.

Pasturing Cattle in Roads.

The Weaker Brethren.

Curing a Horse Pond.

Domesticities at Tim Bunker's.

Takes a Journey.

On Farm Roads.

A New Manure.

Losing the Premium.

A New Enterprise.

Making Tiles.

The Clergy and Farming.

Women Horse Racing,

Beginning Life.

An Apology for Tim Bunker.

On County Fairs.

At Home A^ain.

On Raising Boys.

On Raising Girls,

A New Case of the Black Art.

A Letter from Neighbors.

The Shadtown Parsonage.

Views of Dress.

A Rustic Wedding.

Saving a Sixpence.

On Giving Land a Start.

On Giving Boys a Start.

A Tile in the Head.

Jake Friuk Sold.

The New- York Central Park.

On Irrigation.

Feeding with Oil Meal.

The Farmers' Club.

On Bad Water.

Cattle Disease.

On Seed.

On Breastworks In War.

Lightning Rods.

Buying a Farm.

Topdressing and Feeding After

math.
Painting Buildings.
The Value of Muck.
On Family Horses.
The Horn-ail.
A Commentary on Roots.
Stealing Fruit and Flowers.
The Cost of Pride.
Swamps Turning Indian.
Tim Bunker in his Garden.
On Running Astern.
On Extravagance.
The Fanners Old Age. •
On Sheep Traps.
Old Style Housekeeping.
On Keeping a Wife Comfortable.
Starting a Sugar Mill.
Reasons against Tobacco. .
Trip to Washington.
The Sanitary Commission.
Raid among the Pickle Patches.
Raid among the Pickle Patches.
On Striking He.
Visit to Titus Oaks, Esq.
The Pickle Fever in Hookertown.
On Curing Pickles and Eating

them.
The Cotton Fever and Emigration,
The Cotton Fever and Emigration,
The Food Question.
On Jim Crow.
The Eight-Hour Law.
Base Ball Clubs.
The Rise of Real Estate.

SENT POST-PAID. PRICE, $1.50.

ORANGE JUDD & CO.,

24ii Broadway, Neic-Tork.

DARWIN'S NEW WORK.

TME2 T"AK^IA.TIOT^

OP

ANIMALS AND PLANTS

UNDER DOMESTICATION,

BT

CHi^RLES D^R,"V^I]Sr, MI.^V., y.R.S.. ETC.

AUTHORIZED EDITION.

TT^ITH -A. I» Tl. IB T* -A. O E

BT

PROFESSOR ASA GRAY.

This work treats of the variations in our domestic animals and cultivated
plants, discussing the circumstances that influence these variations, inherit-
ance of peculiarities, results of in-and-in breeding, crossing, etc.

It is one of the most remarkable books of the present day, presenting an
array of facts that show the most extraordinary amount of observation and
-esearch. All the domestic animals, from horses and cattle to canary-birds and
noney-bees, are discussed, as well as our leading culinary and other plants,
making it a work of the greatest interest.

Its importance to agriculturists, breeders, scientific men, and the general
reader will be seen by its scope as indicated in the following partial enumera-
tion of its contents : Pigs, Cattle, Sheep, Goats ; Dogs and Cats, Horses
AND Asses ; Domestic Rabbits ; Domestic Pigeons ; Fowls, Ducks, Geese,
Peacock, Turkey, Guinea Fowl, Canary-bird, Gold-fish ; Hive-bees ;
SiLK-siOTHS. Cultivated Plants ; Cereal and Culinary Plants ; Fruits,
Ornamental Trees, Flowers, Bud Variation. Inheritance, Reversion
OR Atavism, Crossing. On the Good Effects op Crossing, and on thk
Evil Effects of Close Interbreeding. Selection. Causes op Variabii.-
ITY, Laws op Variation, etc., eto.

Published in Two Volumes of nearly 1100 pages.

IPINEXuY ILLUSTRATED.
SENT POST-PAID, PRICE, $6.00.

ORANGE JUDD & CO.,

345 Broadway, New -York City

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