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SYSTEM 



OF 



CHEMISTRY 



m FIVE VOLUMES. 



By THOMAS THOMSON, 

« Ma D« F. R. S« B« 



THE FOURTH EDITION. 



Vol. n. 



» » 



EDINBURGH : 

PRINTED FOR BELL & BRADFUTE. 

SOLD BT JOBir HUSRAT, LONOOIT} AND GILBERT & BODOBf, 

DUBLIir. 

1810. 




«ovnax wtmi ij'-. v 






CONTENTS 



OF 



VOLUME SECOND* 



ses 



Book II. Or Gompoukd Booiei . . i 

Division I. Of Salifiable Bases . . s 

Chap. I. Of volatile alkalies - 4 

Sect. i. Of amtnonia - . 5 

Chap. II. Of fixed alkalies - - 22 

Sect. 1 . Of potash . . ib. 

2. Of soda . . 39 

Chap. III. Of alkaline earths . 45 

Sect. i. Of lime - - 40 

2. Of magnesia - - 60 

3. Of baiytes - - 65 
4* Of strontian . . 73 

Chap. IV. Of earths proper - - 78 

Sect. 1. Of alumina . . ib. 

2. Of jttria - - 88 

3. Of gludna . . gi 

4. Of zirconia - - 93 

5. Of silica - - 90 
Chap. V. Remarks on the alkalies and 

earths - - 106 







1 


^^^^ 






COKTENTS. 






112 


^^^H Chap. 1. Of oxides 


114 


^^^1 1. 


Of water 


116 


^^^H 


Di Ibc oxides of carbon 


137 


^^^B 


Of the oxides of sulphur 


and 




phcphoru. 


153 


^^H 


Of the oxides of aiote 


154 


^^H Cbaf. II. Ofacids . 


icg 


^^^H Class I. Acid products - 


175 


^^H 


Of sulphuric acid - 


m 


^^H 


Of siilphuious acid • 


103 


^^B 


Of phosphoric acid - 


100 


^^^B 


Of phosphorous acid 


204 


^^H 


Of carbonic acid 


207 


^^^B 


Of fluoric acid 


215 
221 


^^H 


Of boracic acid 


^^H Class 


Acid supporters 


227 


^^^h ■' 1 


Of nitric acid 


220 


^^^B "- 


Of nitrous acid 


245 


^^^H 


Of oxymoriatic acid - 


247 


^^H 


Of hyperoxymuriatic acid 258 1 


^^H 


Of arsenic acid 


263 


^^H 


Of tungstic acid 


206 


^^^H 


Of molybdic acid 


267 


^^H 


Of chromic acid 


271 


^^H 


Of columbic acid 


273 


^^1 Class III 


Combustible acids - 


275 


^^H 1 


Of acetic acid 


£78 


^^^^ 


Of benzoic acid 


289 


^^B ^ *- . 


Ofscbacicacid 


298 


^^^L Sot ■uit^-u 


Of succinic acid 


297 


^^^^^^K'- 


Of moroxylic acid 


300 1 







PW- 


Sect. a. Of camphoric add 




302 


7. Of oxalic ftcid 




304 


B. Of mcUitic acid 




311 


B. Of tartaric acid 




315 


10. Of citric acid 




32B 


11. Of kioic acid 




S25 


IS. Of saclaclic acid 




321 


IS. Of uric acid 




3S1 


14. Of laoric acid 




338 


15. Of malic acid 




340 


10. Of suberic acid 




344 


n. Of formic acid 




347 


18. General remarks 




350 


Chaf. IU. Of colorific acids 




301 


Sect. i. Of sulphureted hjdrogea 


302 


2. Of pronic acid 


- 


ib. 


3. Of gallic acid - 


. 


317 


4. Of tannin 


. 


383 


Cbaf. IV. Of compound combustibles 


408 


Sect. l. Of alcohol 


- 


409 


2. Of etber 


. 


430 


3. Of volatile oils 


. 


476 


4. Of fixed oils - 




487 


5. Of bitumens - 


. 


502 


Chap. V. Remarks on the primary 


com- 




pounds 


. 


514 


DITISIDH III. Secondary Compounds 


. 


517 


Chat. I. Combinations of earths 


, 


519 


SCCT, 1. Of earthy combinations in 




general 


. 


520 


2. Of stone-ware 




539 


Chaf. II. Of glass 


- 


555 




PlgC. 

Chat. III. Of salts - - - 565 
Sect. j. Of alkaline andesrthy salts 570 



OrdEK I. Incombustible salts 


574 


Genus l. Muriates 


ib. 


a. Flaates 


004 


3. Borates 


611 


4. Phoiphates 


618 


5. Phosphites 


034 


0. Cn-bouatcs 


638 


1. Sulptutei 


65S 



STE 



U 



CHEMISTRY; 



OF COMPOUND BODIES. 



C^OUPOOHD Bodies are subitznces cotnpased of two 
Oi more sitnple bodies comb in ed together. Now uthc 
simple bodies described in the preceding book, exdi^ 
ding tight and heat, arc 35 in number, if thcj were all 
capable of combining togeihcr, the compounds fDrmed 
by them would amount to a great man; thousands: 
But all the simple substances are not capable of com> 
bintng with each other ; azote, for instance, has never 
been combined with roetal;. This diminishes ibeir 
mrobcr considerablj. Besides, we are siill too little 
acquainted with the nature of caloric and light to be 
able to treat separately of the compounds into which 
ibey enter. Several numerous classes of compounds 
have been already described in t]ie last Book ; for tbc 
teides, sulphutets, phosphurets, and alloys, ore real 
P». IJ. A 



COMPOUND BODIESr 



Book IT. 



DItisIous. 



Salifiable 
baaea. 



compounds. All these circumstances render the com- 
pounds which form the subject of this Book much less 
numerous than might be at first supposed. 

Compound bodies are of two kinds. Some of them 
are formed by the combination of two or more simple 
substances with each other. Thus phosphoric acid is 
composed of phosphorus and oxygen ; and oil,, of hy- 
drogen and carbon. Others*are formed by the combi* 
nation of two or more compound bodies with eacli other. 
Thus phosphate of ammonia is composed of phosphoric 
acid and ammonia ; volatile liniment, of oil and ammo- 
nia. The first of these kinds of compounds I call Pri- 
mary Compounds ; to the second I give the name of 
Secondary Compounds. It will be very convenient 
to describe each of them separately. 

Besides the 35 bodies described in the preceding 
Book, there are a number of others lately discovered 
by the sagacity of Professor Davy, and which we 
omitted for reasons formerly specified. These, when 
combined with oxygen, constitute the important c1 as- 
sess of bodies known under the names of alkalies and 
'earths* These substances form a distinct order bj 
themselves, and which, for that reason, may be descri- 
bed separately. Now these bodies (Including the vo- 
latile alkali) have the property of combining with acid% 
and of constimting the bases of a very numerou set of bo- 
dies called salts. This induced Lavoisier to give them 
the appellation of salifiable bases : a name which I 
shall adopt, though it be somewhat exceptionable, be- 
cause I can think of no other which is not equally so. 
This Book then shall be divided into three parts : I. 
Salifiable Bases. II. Primary Compounds. Ill, 
Secondary Compounds, 



HufUBhi mast, 






DIVISION I. 



ot 



SALIFIABLE BASJES. 



MV the dass of salifiable bases, it is proper to include 
ammoma^ becaosc its properties connect it with the most 
important of the other substances. The salifiable bases 
naturally arrange themselves under the four folio wiug 
headt: 

1. Volatile alkalies 

2. Fixed alkalies^ 

3. Alkaline earths. 
5. Earths proper. 

■t . ■ . . 

These shall form t^e subject of the four following 

Chapters. 



A a 





V 



CHAP, h 



'OF VOLATILE ALRALIES. 



ae 



4 

<M%di. JL RK word Ai.KALr Is of Arabian origin, and was in-' 
troduccd into chemistrj after it had been applied to a 
pbnt which still retains the name of iali. When this ^i- 
plant is burnt, the ashes washed in water, and the wa- 
ter evaporated to dryness, a white substance remains,^ 
ndiicli wtfcalled aiiatt: According to AAeftns Mag- 
nus, who uses the word, it signifies y2rx amaritmdifdr^ 
** the dregs of bitterness *.^ Alkali maj be obtained 
firom other substances besides kali* Aiemists gradnaUjr 
discovered that bodies differing from one another in se- 
veral of their projlerties, had been confounded together 
under the same naiAe. • The word, in consequence, be-- 
came eeneral, and- is now applied to all bodies which 
* possfeinhe''foll6wing'properties : 

1. A caustic taste* 

2» Volatilized bj heat. 

3. Capable of combining with acids, and of destroy- 
ing tbeir'additj. 



« n*Mtrmm CUmkum^ il 4f0i 



^ Soluble in water even when conbiocd with carbo* OoP' ^ 
■icadd. ' '"^ 

5* Capable of convening vegetable blues to green. 

The xlkalies at present known arc three in number i 
X. AmnHMua; 2. Potash t 3. Soda. 

The two last arc called ^ftJ aliaUes, because they 
raquiie » red heat to volatilize them ; the first is called 
^alatUtalioE, because it readily assumes a gaseous form, 
»aA cooscquently is dissipated by a very moderate de- 
gree of heat. 

The fixed alkalies belong lo a succeeding Chapter , 
ihc only volatile alkali at present known, namely, nm* 
■losu, shall be described in (he presenu 



SECT. I. 

3F AMMOHIj) 



JVhhjbnia can be exhibited in a slate, of purity only 
Upd^^tbe form of a gas; It may be .procured in the 
.foUfwing manner : 

\, ^a^intqa rctoitamixture of three parlsofquick- Prepata- 
lime and one- pait of sal ammoniac in ponder. Plunge 
the bfak of. itie retort below the mouth of a glass jar 
filled with mercury, and standing inverted in a basin of 
merpaqr. Apply the heat of a lamp lo the retort : a 
gas comes over, which displaces the mercury and fills 
the jar. This gas is ammonia. 

Aramoiiia was altogether unknown to the ancients ; Hitiorr. 
the alchymists were acquainted with it, though not ia 



▲LXALltS. 



Bonk II. 
Divition I. 



^opcra'es. 



a state of purity^ hting combined with carbonic aaid^ 
and often also dissolved in water. Basil Valenttne de^ 
scribes the method of obtaining it. It was known bj 
the name o(voiaiik aUali; it was also called hartsborn, 
because it was often obtained by distilling the horn o£ 
She hart ; spirit o/urim^ because it may be obtained by 
the same process from urine ; aad spirit of sal ammo^ 
niaCy because it may be obtained from that salt. Dr 
Black (irst pointed out the difference between ammonia 
and carbonate of ammonia, or ammonia combined with 
carbonic acid ; and Dr Priestley discovered the method 
of obtaining it in a state of puritji by the process dc* 
scribed in the beginning of this Section. 

2. Ammonia in the state of gas is transparent and co- 
lourless like air ^ it^ taste is acrid arid caustic like that 
of the fixed alkalies, but not nearly so strong, nor doea 
it like them corrode tliose animal bodies to whi/ch it if 
applied : its smell is rcriiarkably pungent, though not 
unpleasant when sui^icjcntly dilujic^. Its use as ^ sti* 
mulant to prevent fainting is well known. 

Animals cannot bieath it without death. When • 
lighted candle is let down into this gas, it goes cot three 
or four times successively ; but at each time the^me 
is considerably enlarged by the addition of another flame 
of a pale yellow colour, and at last this flame ttescenda 
from the top of the vessel to the bottom *• 

Its specific gravity, according to the experfflsenta of 
f^irwan, is 0*600, that of air being 1-00 f* While Mr 
Davy found it 0*5505 1« Messrs AUen and Pepyf 



* Prieitleyi i". 381. 



t On FhhptUm^ ^ tt. 



iMktlj foond it O-6022 *. At the temperature of 60®, a , Qa^ t 
Imndied cubic inches of thb gas weigh, according to 
Kirwan, 18*10 grains, according to Davy, 17*068, ac* 
oording^ to Allen and Pepjs, 18*67. Hence it is to 
common air neiarly as 3 to 5. - - 

When exposed to a cold of -—45^ it is condensed into 
a liquid, which agaiivassumes the gaseous form nvhen 
die temperature is raised f. ' Whtt passed through a 
red hot tube of porcelain or glass, it is totally decom- 



and converted into hydrogen nnd azotic gas %• 
That this experiment may succeed, the diameter of the 
tube must not be too great. - 

3. It combines very rapidly with water. When a bit- 
of ice is brought into contact with this gas, it melts and 
absorbs the ammonia, while at the same time its tern* 
perature. is diminished. Cold water absorbs this gas 
almost instantaneously, and at the same time heat is 
evolved, and the specific gravity of the water is dimi- 
nished. Water, by my trials, is capable of absorbing 
"ISO times its bulk of this gas ; while, in the mean time, 
the bulk of the liquid increases from 6 to 1 0. The 
specific gravity of this solution is 0*900, which just ac- 
cords with the increase cf bulk. It is in this state 
that ammonia is usually employed by chemists. The 
term ammonia almost always means this liquid solution 
of ammonia in water. When heated to the tempera- 
tare of about 130^, the ammonia separates under the 
form of gas. When exposed to the temperature o 



* Davy Ml iLe deccififtjitlcn and cemfOfiticm cf lie jixtd allatUi. PliL 

4 Morvm, Aw, Jt Cim> tw^ 293. IPriettl^y, ii. i^. 






Bodkll. 



it crystallizes ; aod when suddenl/ cooled dovnf^^ 
to — 68^, it assumes the appearance of a thick jellj, ud '' 
has scarcely any smell *• • 

It follows from the experiments q$ Mr Davy, that a 
saturated solution of ammonia is composed of 

74*03 water 

MO'OQ 

The following Tablk, drawn up bj the same iage^ 
aious chemist, exhibits the proportion of water and am« 
imonia contained in lOO parts of liquid ammonia of dif* 
ferent specific gravities f. 



4 



* 



^, 



I 


Specific gravity. 


Ammonia. 


Water. 




0*9054 


25-37 


74*63 




0-9166 


S9'07 


77*93 




0-0255 


10*54 


80-46 




0'Q32($ 


17*52 


82-48 




0-9385 


15-88 


84*12 




0*9445 


14*53 


85-47 




0*9416 


13*46 


. 86-54 




0-9513 


12*40 


87*60 




0-9545 


11-56 


88-44 




0-9573 


10-82 


89-lS 




0*9597 


10-17 


89-83 




00619 


0-60 


99P40 




0*9684 


9-50 


90-50 


i •• 


0*9d39 


9-09 


90-91 


J * 


0-9713 


7*17 


92-83 



'^: 



4. Ammoniacal gas is not altered by light; bnt wbeii 



^ f oorcroy and Vau^iidiiiy Amm. dt C&nt* ixiz« s8^ 



oiygcD. 



AMMOXIA. V 

jdectnc spaiks are made to pau through it, the bulk of ch»p. i. ^ 
tbc gu is considerably incieased, and it is coBVerled AaiMiof 
Brto hydrogen gas and aiotic gas •. Hence it follows '^'*"*"I' 
thmt omoionia consists chiefly of hydrogen and azote. 
By tlus pTOCCSt Bcnhollet converted l-l cubic inches of 
icnmoni^cal gas into 3*3 cubic inches f . 

i. Xhisgas has no effect upon oxygen gas while coM ; 
bntwbcn a mixture of the two gases is made top 
ibmigh * red hot porcelain tube, a detonation takea 
plicC) water is formed, and azoiicgas emitted. Hence 
wc KC that aiomonia is partly combustible. lis hydco- 
Mneofflbines with the oxygen, and forms water, while 
llie uole makes its escape in the form of a gas t. If 
the proportion of oxygen gas be considerable, nitric 
acid is also formed, in consequence of the combination 
oftheaiote wilb the superabundant oxygen j. The 
suae decomposition sod detonation take place if com- 
non ail be used instead of oxygen gas. 

6. Sulphur is the only one of iba simple combusli- - 
bits that oombiDes witlt ammonia. Hydrogen pro- • 
duces no change upon it whatever i but phosphorus and 
charcoal act with considerable effect in high tempera- 
tures. 

It combines with sulphur in the stale of vapour, and 
fbraiii sulphuret which decomposes water, and forms 
hy^vpirrtttl ivlphuret of ammonia, known formerly by 
llie Daac d fuming liquor of Boyle, because it was ftrsi 
described by that philosopher ^. It is commonly pre- 






\ Shaw't a^, ii. ;& 



4 PovtiTej, u- ijb 



1# 



ALKALIES* 



Bo0klt 
Divttton i. 



coBibttiti- 
bkt. 



OfaMuU 



ptred by distilling a mixture of five parts ot sal ammo« 
niaC) five parts of sulphur, and six of quicklime. It is 
a liquid of a red or rather deep orange colour, and ex* 
bales a fetid odour, in consequence of an excess of am- 
xDonia which it contains. Its nature was first pointed 
out hy Berthollct *. 

Phosphorus produces no change on ammoniacal gas 
while cold ; hut wheo this gas is made to pass through 
phosphorus in a red hot porcelain tube^ it is decompo- 
sed, and phosphureted hydrogen ga8> and phosphuretell 
azotic gas are formed f. 

Charcoal absorbs ammoniacal gas, but does not alter 
its properties while cold. But when the gas is made to 
pass through red hot charcoal, part of the charcoal com* 
bines with it, and forms a substance known by the name 
^ fruJuic acidt* 

*7. Ammonia is not acted on by azote ; but it com- 
bines rapidly with muriatic acid \ the two gases con- 
creting into the Bciid salt called murUti of amnnmia* 

. 8. Ammonia does not combine witbthe metals; but 
it changes some of them into oxides, and^then dissolves 
4hem. The oxxdizement is evidently in consequence of 
the decomposition of part of the water with which the 
ammonia is combined 9 for hydrogen gas is emitted du- 
ring the solution. Copper and zink are oxidized by tha 
action of ammonia ; as are also tin and iroib, though 
only superficially «* Scarcely any of the other metals 
fare altered by its action. 

Liquid ammonia is capable of dissolving the oxides 



• Amh^ it Clim, XXV. XJJ. f 

* Schecl«, ii. 183 ; and Clouet,.iu. A 






^ lilvcT, copper, iron, lin, nickel, zinci bi&niutb, and Chap, i 
cobalt *. When digested upon ibe oxides of mercury, Diuolics 
lc%d, or msoganese, it is decomposed, water is formed, |^^ 
\>y the union of the hydrogen of ibe ammonia wiili 
tht oxygen of ibe oxrdcs, and szotic gas is emitted +. 
If • considerable beat be applied, niiric acid is formed 
Uihesuoe time with water t. Several other oxides 
an also partly deoxidiiccd uhen ammonia is poured 
inuitiieir solutions in acids. The ammoniacal solution 
of die peroxide of copper is of a fine blue colour, and, 
atcording to Sage, capable nf crjsialliziiig. When heat 
h applied, tbc ammonia is partly driven off, and partly 
ddumposed, by the connbinaiion of its hydrogen with 
tbt oxygen of the oxide. 

!), Ammonia combines readily wilb the peroxides ot 
sold and silver, and forms uiih ihrto two compound^ 
bametly known by t!ie names oi /ulminatitig gold aitd 
falmiBBting lihtr ; btcause, when healed or rubbed, 
ihey cxplcdc wiUi great violerce. It combines also 
with Ihe red oxide of mercury. 

Fulminnting gold, knowoatso by the ns-jae ai aurate fu'"'™ 
cfamaania, taiy be prepared by dissolving gold in ni- 
tro-muriitic scid, diluting the scluiion nith thrice its 
weiftht of water, and then dropping in pure ammonia 
by little and little as long as any precipitate is formed ; 
tiiiing care not to add iro much, because in that case 
pMI of the precipitate is again dissolved. The prccipi- 



■mil qnuiiuin. Ibi prroiiacijiivii H uuvluUf . 
tlUcof (0t»li, iicordii.g lo ThcnarJ. 

IWncttFti' Tww.— Foutcroy, T. ijj. 



in kJWkxnx. 






sue, nbselx U oc a jellcw caiocr, is a be 
;ere water, dried slovlj opoa iineriHg' pspcr, and 
psc inco a p&iai : wfiico, fio p r e i c n a •'-+**"T^ ought 
nee CO be cocked, bat x3 Booth cm c wd witk 
rag^or a slip oi paper. This powdaris 
j[foU ; firbich is campoacd of £vc pans of jcDov ozidc 
ol gc!(d «id ooe pact of tnwiwiia *. The [■rpa i iio B 
of this powder is described bj Basil Vilmiiars aad its 
fwgnlar properties ezdled the at l emion of all mccccd 
iftg cheasiia. Varioos attempcs were laade to arromit 
for iu folmioatiiig property, but withom snooea^ till 
Berg^un published his disserution oo it ia 17C0. He 
dettoostfaiad, that it is acompoood of amiaonia and 
jellow oxide of gold : that during its explosion the 
oaide b reduced, the annDouia decomposed, and the 
axote, which it contained, set at liberty in the form^if 
gasf • These facts (partly discovered by Sdiede) led 
Jlin to explain the explosion as follows : Ainmonia as 
aomposed of azote and phlogiston,. When heat is ap- 
plied to fulminating goldy the phlogislfpxombines with 
the oxide, and fDrms gold, while the a;u>te flies oflfin 
tlic form of gas. The iexpqimcals of Bergnoum and 
Scbeela were rtpeatod and confirmed by ]3erthoUet 10 
iltb ; and the nature of oxides haying been preyippsly 
.ascertained by Lavoisier, he was enabled to give a more 
•satisfactory explanstix)n of the phenomeptn. Puriag 
the. explosion, the hydrogen of the aopmoma combing 
with tlie oxygen of the oxide, and forms water ; the 
I'old is reduced, and the azote evolved in the form of 



33: 



* JkrgmMiiii. 155. 

t Bf rgmani iu 153 ; and Sclieck m Frnr, p. 137. 




AitHOttlA, 

gwy. The grest expansibility of this gas by treat ex- 
pUios tlK violence of the explosion. 

Foliiunatitig gold explodes when struck vialcntly, or 
when triturated in a mortar, or when heated to » tcm- 
_I)cratarchctwecn 248''su]d 54"- The noise is tremen- 
dottsi and when tn any considerabl-e quantity (l2 grains 
for instance) it lacerates the melalUc plate on which it 
i> placed. When healed in close vessels, sufficiently 
strong to resist its action, it is reduced silently, and 
withoac any tnailcs of violence *. Its force was corn- 
iced with that of gunpowder by the Royal Society, 
but fonnd inferior. 

Fnlmiaating silver was discovered by BerthoUet in j. 
nSff. It may be formed by dissolving very pure sil- ^ 
ret in nitric acid, and then precipitating it by lime wa- 
ter. The ptecipiiaie is put upon filtering paper, which 
, absorb* the water and the nitrate of lime wiih which it 
; WIS mixed ; then pure liquid ammonia is poured upon 
Kt, and allowed to remain for 12 hours ; il ts then de- 
«:«ited off, and the black powder, on which it stood, i^ 
placed cautiously, and in very Small portions, upon bits 
«[ filteriog paper. This powder is fulminating silver. 
J£.yea while moist it explodes with violence when 
struck by a hard body. When dry, the slightest touch 
ti mfiicient to cause it to fulminate. When the lii^uid 
decanted off" this powder is heated in 'a glass retort, an 
tSavtactacB takes place, azotic gas is emitted, and 
small crystals makt their appearance, which are opaqoe, 
and luiT« a metallic brilliancy. These fulminate when 



14 ALkALTES. 

Book II. touched, ctcn though covered by the liquid, and ofFeb 
» y I ■ break in pieces the vessels in which thej are kept *• 

The theory of this dangerous powder is the same aa 
that of fulminating gold. It is a compound of ammo- 
nia and oxide of silver. Friction, or the application of 
heat, occasions the combination of the oxygen of the 
oxide with the hydrogen of the ammonia ; water it 
formed, the silver is reduced, and azotic gas emitted* 
AmmoDit- Ammoniacal fulminating mercury was lately disco- 
ting mcrcu- vered by Fourcroy. It may be formed by digesting a 
'^' strong solution of ammonia in water upon the red oxide 

of mercury. After the process has continued for eight 
or ten days, the oxide assumes a white colour, and is 
at last covered with small crystalline scales* In this 
state it detonates loudly upon ignited coals in the same 
manner as fulminating gold. It loses its fulminating 
property, and undergoes spontaneous decomposition, hi 
a few days. When exposed to a low heat, the ammo- 
nia is driven off, and the red oxide assumes ita former 
appearance f • 
Compo>i. ^* ammonia has the property of detonating with 

tion of am- nifre, chemists had unanimously aereed that it contains 
phlogiston. Scheele first demonstrated, that when it 
is decomposed by means of the oxides of manganese^ 
arsenic, or gold, azotic gas is set at liberty, while the 
oxide is reduced %• Hence he concluded, that it is com- 
posed of azote and phlogiston ; and Bergman coincided 
with him in opinion. Dr Priestley discovered, that 



• BerthoUet, Am, de Cbim i. 54. 

f J9ur»4h jftbi Ptyul InstituthH^ i. 256. 

t Scbeclc, i. ^s and 155. FfODch Tniit.^Sch€ek on Flrtf p. r3/« 

t 



AMMONIA. IS 

vrhen electric explosions are made to pass ibrough this , Ch^i. ^ 
gas, its balk is gradually augmented to thrice the space 
which it foi:^erlj occupied } and a quantity of hydro- 
g^ gas is produced. The same ingenious philosopher 
applied heat to the red oxides of mercury and lead con- 
fined in ammoniacal gas. The oxides were reduced, 
water was evolved, the ammoniacal gas disappeared, 
and instead of it, there was found a quantity of axotic 
gu*. These experiments, and those of Scheele, led to 
the coadnsion, that ammonia is composed ^f azote and 
bjdrogen i a conclusion which was fully established 
hj the experiments of BerthoUet, published in the Me- 
moin of the French Academy for 1785. This acute 
philosopher repeated the experiments of Scheele and 
Fticstley, and applied to them the theory of Mr Lavoi- 
sier, and added also several very decisive ones of hia 
own. The most important of these is the mutual de- 
composition of ammonia and oxy muriatic acid. When 
solutions of these bodies in water are mixed together^ 
inc&rvescence takes place, azote is disengaged, a quan- 
titj of w^ter formed, and the oxy muriatic acid is con- 
verted into common muriatic acid. Now the substan- 
ces mixed were ammonia and oxy muriatic acid, which 
is composed of o^ygun and muriatic acid $ the pro- 
ducts were, muriatic acid, azote, and water, which is 
composed of oxygen and hydrogen. The oxygen of 
the water was furnished by the acid ^ the other pro- 
ducts must have been furnished by the ammonia, which 
has disappeared. Ammonia, therefore, must be corn- 
nosed of azote and hydrogen. It follows from Mr Ber- 



• Priestley, ti. 396. 



19 ALKALIES. 

B^^I* tholkt*! experiments, thtt ammonia is com] 
* ^ f parts of azote and 29 of hydrogen *. Accc 
Attttm*s calcuhtion it is composed of 121 p 
and 32 of hjdrogenf. Hence 100 parts 
are composed of about 80 parts of azote ar 
drogen. The experiments of BerthoUet ha 
farther confirmed by those made more h 
I^svy tf snd indeed were acceded to by all 
unexceptionable and decisive. But the unc 
covery by Mr Davy, diat the fixed alkalies 
oxides, led that illastrioos chemist to sosp 
monia also might contain oxygen in so sms 
tion as to escape notice. The possibility o 
» was not to be doubted, as when ammonia ' 

posed by means of electricity or heat, the ox^ 
present might combine with hydrogen, s 
amall a quantity of water as to remain invi 
the gases evolved. A set of experiments n 
pose to ascertain the pointp soon convince! 
that oxygen is actually present in this alk 
pufe dry aauBouiacal gas was fussed over i 
wire confined in a platinum tube, the iron 
oxydized, and a little moisture was depo! 
experiment rendered the presence of oxyge 
nia somewhat probable ; but it cannot be c 
conclusive, unless we could be eertain that 
air was effectually excluded ; which it 



* BerthoUet detcmincd the compoocot putt 
poiifig it by ekctridtx, and exploding the new 
de Phju nix. 177. 

i P6iL Trmu, 17^ ^tffii t 




it 

J^^ ^\ is pUctd in contact nritii a solutioa of nnMns, ind 



tkc ciraiit completed. It gradnallj incresKS ia toIuibc^ 
and when expanded foor or ire tines its fanner bolk» 
itsbtKita b eco m e s a soft solid. The experiment is easacr^juid the 
amdgammorepermanent,if sal ammoniac sfigkdjmoisU 
cnad be subsbtmcdfor liquid ammonia. Mr Dar^made 
a cavitj in a piece of sal ammoniac sUghtlj nsoisfienedp 
plaoed it on a plate of platinum attached to the positive 
end of the galvanic baCteiy, pot into tbo cavitj about 
50 grains of mercurjr, and brought ia contact with the 
mercurj a jdatinum wire attached to the negative end 
of the batterj. A strong effervescence took place, mncb 
beat was evolved, and ibo globule in a few aaimttM baiA 
enlarged to five times its original bulkp and had Ak np» 
pearanoe of an amalgam of zinc This- amalgaaa^ at 
the temperature of 70^ or 80^» is a soft solid of the coo* 
aislcnoe of butter; at 33^ it is a firm cfystalliaed maan- 
in which small fiacets appear^ bnt having no perfectljr 
defined £srm. Its specific gravitj is below 9w Wbea 
exposed to air it soon bec o me s covered with %■ whitn 
cmst of carbonate of ammonia. When thrown into wa- 
ter, a qnanlit j of hjdrogen is evoWed e^pal to half its 
bulk, the aoercorv is revived, and the water beoomos m 
weak solntion of ammoaia. When confined in a g^tis 
portion of air^ the air increases considerably in vohnncy 
and pare mercnry re^appears. Ammoniacal gas amount* 
ing to 14- or if, the volume of the amalgam isevolved^ 
and a quancitjof oxjgen equal to ^th or |th of the am» 
flsoaia disappears. When thrown into muriatic add 
gas it becomes coated with muriate of ammonia, and a 
Kttle hydrogen is disengaged.. In sulphuric acid it be- 
comes coaled with salpbuiie of ammonia and snlphnr. 
All attempts made by Mr Davy to preserve this amal* 



gam ftUtA, o«riitg to the imposilbilitf of freeing it en- 
tirely of Water. When put into a glass lube, or when 
coiil!ncd nnder naphtha or oils, the mercury ieparated, 
km Aonia was formed, and a quantity of hydrogen evol 
ved". 

Ii is ottvioos, from the preceding observadons, thai 
fhe amalgam thus formed, <omisted of the basis of am- 
tsonia combined with mercury. This basis has so strong 
SI tffiniiy for otygen that it immediately decomposes 
•ater, and is convened into ammonia while hydrogert 
fa evolved. Hence appears to be the reason why hydro- 
gen always appears during the destruction of the amal- 
gam, «nd why the amalgam cannot be preserved. The 
quantity of basis of ammonia contained in 50 grains of 
mcrcary thus converted into a solid amalgam, it is evi- 
dent from the preceding detail cannot exceed -^ih of 
X grztn. That so minute a portion of matter shbuM 
fluke so striking a change in so great a quantity of m6r- 
caty, and reduce its specific gravity so enormously, ig 
perhaps the most extraordinary fact that has yet appear- 
ed tn chemistry. 

Oxygen then appears to be a constituent part of am- 
monia t (he other ingredients of it, when deprived of 
that principal, acquire the property of amalgamating 
with mercury, and of course must be of a metallic uk- 
ttire. This is another unexpected and extraordinuy 
&cl. What is this metal evolved From ammonia, and 
to which the name of ammonium has been given ? Is 
it ift (act composed of one or of two metals ? Are aZote 



.^^ 



* DlT7'i Xlitlruhtmicid Ranrtiir M ihi Oittmftiitm tftli Eitlh, 

»i. ftlt. 7Wa>. iCaB. 



2C AIJCAUIS* 

^^Jj' and bydrogem each metals in the gaseoos state, or are 
they meuUic oxides, or do tbej constitute a single me- 
tal when united together ? These are questions which 
the present sute of the subject does not enable us to re« 
solve. The experiments seem rather more favonnU>le 
to the last supposition, which is the opinion cfotertaioed 
bjr Bcrzelius, but thej are bj no means capable of de- 
ciding it. 

Several successful attempts have beea made to form 
V^raatam ammonia^ artificiallj. Dr Austin indeed £ailed ia bis 
attempts^ to form it \>j uniting together hjdrogen and 
azotic gases bj means of heai , electricity, and cold. And 
now that we know that this alkali is of a more oom^ 
Ijonnd nature than this philosopher supposed, we can- 
not be surprized at his failure. It could not be doubt* 
cd, however, that the alkali is often formed during 
different chemical processes. Dr Priestlej * and Mt 
Kirwan \ had actually produced it even before its com* 
position was known. It had been found, that when tin 
is moistened with nitric acid, and after being allowed 
to digest for a minute or two, a little potash or lime is 
added, ammonia is immediately exhaled. The nitric 
acid and the water which it contains are decomposed ; 
the oxygen of each unites with the tin, and reduces it to 
the state of an oxide ; while at the same ticne ihe hy- 
drogen of the water combines with the azote of the acid 
and with some oxygen, and forms ammonia, which ia 
driven off by the stronger aiBiiity of the potash or lime. 
Dr Austin succeeded also in forming ammonia by sevc'. 
ral other methods. He introduced into a glass tube 



« Om A^r^ II. 41. t Om H^ik Mr, $ iii. 



AMUOtULi 



n 



filled with mercnry a little azotic gas, and then put in* 
to the gas some iron filings OMHstoned with water. The 
iron decomposes the water, and combines with its oxy- 
gen ; and the hydrogen^ meeting with azote at the mo- 
ment of its admission, combines with it, and forms am« 
monia. This experiment shows, that the gaseous state 
of the azote does not prevent the formation of ammonia. 
The experiment succeeded also when common air was 
used instead of azote, but a longer time elapsed before 
the extrication of ammonia became sensible. Hence it 
is likely that ammonia is evolved whenever iron rusts 
in contact with water and air *. 



Cliap.1, 




J^s-. 



♦ Pbil. Trofu. I7S8, p. 379. 



99 wjxzpAmAian, 

9ookll. 
PmioQ L 



CHAP. n. 



OF FIXED AUUUfiS. 



jL hk fixed ftlkilies are distinguished from the volttUf 
in not being gaaeoas. They majr be exhibited pore in 
« solid state. Their taste is much more acrid. Twa 
fixed alkalies only are at present known ; namely, /o/- 
Cib and soda. They form the subject of the fallowiDg 
Sections. 



SECT. I. 



OF POTASH. 



Metlwd of If a sufficient quantity of wood be burnt to ashes, and 
potMhT^ these ashes be afterwards washed repeatedly with water 
till it comes off free from any taste, and if this liquid be 
filtrated and evaporated to dryness, the substance which 
remains behind is potash ; not, however, in a state of 
purity, for it is contaminated with several other sub- 
atances, but sufficiently pure to exhibit many of its pro- 
perties. In this state it occurs in commerce under the 
mme of /ola(^. When heated to redness^ many of ita 






tmpuriues are burnt off: it becomes much whiter than chxf. 11. 
beforehand is then known in commerce by the name of 
prarl-ash. Still, however, it is contaminated with ma- 
ny forei|;n bodies, and is itself combined with carbonic 
scj4 gas, which blunts all its properties. It may be ob- 
tatDcd perfetily pure by the following process : 

1. Mix it with twice its weight of quicklime, and ten 
Uncs its weight of pure water : Boil the mixture for 
•OHM houra in a ckan iron vesselj or allow it la remain 
for 4S hours in a dose glass vessel, shaking itoccasion- 
■lly. Then pass it through a liller. Boil lite liquid 
obtaiocd m a silver vessel very rapidly, till it is so much 
c o neentratcd as to assume when cold the consistence of 
hoBcy. Then pour upon it a cgu^ntily of alcohol equal 
in weight to one-third of liie pearl-ash employed. 
Shake the mixtnre, put it on the fire, let it boil for a 
minute or two, then pour it into a glass vessel and cork 
it Op. The solution gradually separates itself into two 
strvta : the lowest consists of the impurities, partly dis- 
solved in water and partly in a solid slate ; the upper- 
matt consists of the pure potash dissolved in alcohol. 
Bad is of a reddish-brown colour. Decant this alcohol 
SoJntion into a silver basin, and evaporate it rapidly 
mi ■ CTU&I forms on the surface, and the liquid below 
acquires such consistence as to become solid on cooling. 
T'ben pour tbe solution tolo a porcelain vessel. Wlicn 
cdd, it concretes into a fine white substance, which is 
pure potash. It must be broken to pieces, and put into 
an air-tight phial. 

For this process we are indebted to Berthollel *. The 



fi4 riZEO ALKALIES^ 

H'lok U. following, which was fir^ proposed by Lowitr of Fe* 
tersburgh, is less expensive^ Ihe potash ot commerce 
and quicklime arc to be boiled together, ^s above descri*- 
bed. Tilt filtered Hqugr is then to be evaporated till a 
thick pellicle appears on its surface, and afterwards al- 
lowed to icool ; and all the i:rystals which haye foraie4 
are to be separated, for they consist of foreign s^ts. 
The evaporation is then to he continued in an iron pot ; 
gnd, during the process, the pellicle which forms on the 
surface is to be carefully taken off with an iron skim- 
mer. When no more pellicle ap ears, and when the 
matter ceases to boil, it is to be taken off the fire, and 
roust be consjtantly agitated with an iron spatnla while 
coolingw It is then to be dis^solved in double its own 
weight of cold water. This solution is to be filtered 
and evaporate() in a glass retort * till it begins to depo- 
fitr regular crvstals. If tho mass consolidates ever so 
little by cooling, a small quantity of water is to be add- 
ed, and it must be heated again. When a sufficient 
number of crystals have been formed, the liquor which 
swims over Jthem, and which has assumed a very brown 
colour, must be decanted off, and kept in a welUclosed 
bottle till the brown matter has subsided, and then it 
may be eyaporat^ed as befo^re, ^d more crystals ob- 
tained f . 

The theory of these processes is obvious : The lime 
^para^es the carbonic acid, for which it has a stronger 



* Dr Kennedy obtenrtt, very justly, thtt t ghn retort ought not to 
be employed, becauie potash in this ittte Uitsoivci glass. S^n. Tr^nf 

f Nicholaon*! /•mrMl^ i. 164. 

• • • 



^fitnity ; and the alcohol or the evaporation separate all 'Chip.H.^ 
Um other foreign ingredients. 

A still simpler nieihod is employed b Klaproth. He 
boilseijualpaitsofsalt of tartar '^carbonate of potash jre- 
pared from tartar), and carrara marble or oysier shells, 
boml to lime, with a suflicient quantity of water, in a po- 
lishcdirOD kettle. The ley is then strained through clean 
linen, and though still turbid, is reduced by boiling, till it 
eontain about one half its weight of potash. It is then 
inssed a second time through a linen cloth, and set bye 
in s glus bottle. After some days, when ihe ley has 
become dear of itself, it is decanted off from the ledi- 
nient tnlo another bottle *. 

As potash is never obtained at first in a state of pun- BliA'idlt- 
ty, but always combined with carbonic acid, it was long ihecauieef 
before chemists understood to what the changes pro- *' '^' 
duccd upon it by lime were owing. According to some, 
ilwas deprived of a ijuanlity of mucilage, in which it 
bad forruerly been enveloped ; while, affording to 
Mhers, it was rendered more active by being more com- 
mioDtcd. At last, in 1156, Dr Black proved, by the 
moU Ingenioas and saiisfaciory analysis, that iUk fotati 
which Ihe world bad considered as a •■imple substance, 
was leally a compound, consisting of potash and carbo- 
nic acid i that lime deprived it of this acid ; and that 
it became more active by becoming more simple. 

While Dr Black was thus occupied in Scotland, Mr 
Meyer was employed in Germany in the same re- 
searches J from which, however, he drew very different 
CDDClusions. His Essays on lime appeared in Ilfif. 



• Kltpiotli' 1 Biiir'f, i, Prchee, p. n 



FIXES lUBAUBa. 

■Pouring fnto litae-WBter a sohilion of potash (carlentOt 
e/potaih'), he obtained a precipitate, which he found 
not to difier from lime-stone. The alkali had therefore 
deprived Ihe liine of its causticity and its nclive proper* 
ties i and these very properties it liad tt»elf acquired. 
From which he concluded, that the causticity of limt 
was owing to a particular acid with which it had eofB> 
bined during its calcination. The alkali deprived the 
lirnc of this acid) and therefore had a stronger Affinity 
for il> To this acid he gave the name ofaeitium pingnt 
or cotiiticvn. It was, according to him, a subtile e]a«> 
tic mixl, artalogoiis to sulphur, approaching very nesr* 
ly to the nature of fire, and actually composed of ttt 
acid principle and fire. It was expansible, compressi- 
ble, volatile, astringent, capable of penetrnting all 
sell, and was the cause of causticity in lime, alkalie*, 
and metals. This theory was exceedingly iogeniousi 
and it was supported by a vast number of new and im- 
portant facjs. But notwithstanding the reputation and 
acknowledged genius and merit of its author, it never 
gained many followers ; because the true theory of 
cauaticity, which had been already published by Dr 
Black, soon became known on the continent ; and notv 
withstanding some opposition at first, soon carried coov 
viciioti into every unprejudiced mind. Mr Jacqntu, 
botanical professor at Vienna, published a latin disser- 
tation in defence of Dr Blank's doctrine in nep. This 
work was opposed in mo by Crana, physician to ths 
king of Prussia, who endeavoured to defend the hypo- 
ihests of Meyer, who was now dead, in a very elaboroM 
treatise. The subject was resumed by Mr Lavoisier 
in 1174 in his physical and chemical e&says. He re- 
peated Ihe experiinents of Cr Black and his disciples^ 



ihem in every particular. Since that _Clii p.ll. 
tiam ibe hypotheu* of Meyer seems to have been aban- — 

doocd hj e»ery one. 

That potash \\n% known to the ancient Gauls and 
Germans cannot be doubted, as ihey were the inven- 
tor* of ioap, which, Piiny informs us, they compcised of 
ashes and tallow. These ashes (for he mentions the 
uhn of the beech-tree particularly) were nothing else 
but potash ( not, however, in a stale of purity *. The 
■na, loo, mentioned by Aristophanei and Plato, appears 
to have b(«n a ley made of the same kind of ashes. 
The akbymt&ts were well acquainted with it; and it 
has been in every period very much employed in che- 
aiical researches. It may be said, however, with ju&tice, 
that till ficrthollei published his process in ibe year 
17S6, chemists had never examined potash in a slate of 
oomplcle purity +. 

2. Potash is a brittle substance of a white colour, and Pt'opcrtiet 
a smell resembling ihai which is perceived during the 
slacking of quicklime. Its taste is remarkably acrid; 
and iris so eueedingly corro>ive, that when applied to 
any part of the body, it destroys ii almost instantaneous 
Ijr. On account of this property, it hak been called 



• Piiaiia.1ml.c51. 

t Ponnh vai long dUtiDp)uhecl b; the name of vigilaUi atiali, be* 
iliHf It ii cibiimcil friiin vcgttible*. and Ikuuk it w lun>; ibpughl to 
be pttuliir to the Tcgciiblc kingdom; but thi> it now knnwn in bea 
miKike. ll Tnu called ^K> <</' i/'Krur, brcaUK it mi\ be obtained b; 
banuDg the bH called Ittlar- Mr Kirw:n bu given it ibe name of 
Imti'ti*! Vn Pcan<inhi>ii>ltedilv.2>iid'.; KlupioibiaJi,' and Dr Black 
HmrH By m'lM Biititb thcnuut t ii 'atlcd fo«>i ; but th.i tc m, in 
cemnon hagmcc, lignifiei the ciibocue ol potuh, or the poutb of 



2$ riZCB ALKA1IE8. 

•ook IT. edustic, and is often osed bjr surgeont^ under tbe ntine 
' of the foumial cautery^ to open abscesses, and to destnrf 

useless or hurtlul excrescences. Its specific gravitj h 
1-7085 1. 

When heated it melts ; at a red beat it swells, and 
evaporates slowlj* in a white acrid smoke* A stra^ 
•heat gives it a greenish tinge, but produces no other at 
teration in it. Potash is not altered bjr' exposure to 
light. 

When exposed to the air, it soon attracts moisture^ 
and is converted into a liquid ; at the same time it com* 
bines with carbonic acid, for which it has a strong af- 
finity. 

Tti cmnl>i- ^* ^^ ^^' ^ ^^"^7 Strong affinity for water. At thecom- 
aat^ with mon temperature bf the air, one part of water dissolvea 
two parts of potash. The solution is transparent, very 
dense, and almost of the consistence of oil. It is in this 
state that potash is usually employed by chemists. 
When four parts of potash in powder and one of snow 
are mixed together, the mixture becomes liquid, and at 
the same time afibrds a quantity of caloric. This mix* 
tore was employed by Lowitz to produce artificial cold* 
When the aqueous solution of potash is evaporated to a 
proper consistency, the potash crystallizes. The shape 
of its crystals is very different, according to the way ia 
which they have been produced. When allowed to 
form spontaneously, they are octahedrons ingroupes,aBd 
contain 0*43 of water * : When formed by evaporatioa 



1 

I Hsnenfints, Attn, it Chim, itrlii. ix. 

*. Acciording to Prou«, the bydnte pf potaah contiiotonly O'^Q of 
fer. Jtifn i$ Pbyt, lix. a66. 



on the &n, they usume the figure of very thin tranapa- Cbap. IL 
rent blades of cxuaordinary magniiude, wbich^ by an 
snenbUge of lines crossing each other in predigious 
numbers, present an aggregate of cells oi cavities, com- 
moDly so very dose, that the vessel may be inverled 
without losing one drop of the -liquid which it con- 
tkiost. 

4* Potash shows no disposition to unite with oxygen, Actioaoo 
neither is it altered by the action of any of ibe cotn- '"'S'"' 
poonds into which oxygen eAlers, though it has a strong 
telulency to unite with several of these compounds. 

5. Il unites with none of the simple combustibles ejt- ^'o "imple 
«cpt sulphur. Carbon and hydrogen do not act upon it blet. 
at-atl ; neither does it produce any alteraiion in them, 
bot it acts upon phosphorus with considerable energy. 

\Vhcn three pans of sulphur and one of potash are Sulphurec 
tritarated together in a glass mortar, ihe sulphur ac- " '"'"' 
quires a green colour, the mi slure becomes hot, and ex- 
hales an alliaceous odour. It griidually Httracts moisture 
Crom the air, and is luially soluble in water *. When 
two parw of potash and one of sulphur nte heated in a 
crucible, they melt aiid combine, ajid form ztulphtiret of 
fMOib. The potash of commcice m^iy be also tmploy- 
cd; for |he carbonic acid tep3r-.iics in the form of a gas 
duriitg the comhtnaiion of the potatih and sulphur. 
Wh«n the fusion is compkif, tlie sulphurel is to be 
{KWtcd upon a narble slab i a£d a» won as it congeals, 
il miul be brokefi \a jilcces/ aod set by in a well- 
eoiked phial. 

Su)phyi«t of potash, thus prepared, is of a biown co- 



) NicboLuD'* /HtntI, i. 1(4. • Fourircy. il. 103. 



\-^£:; AIJCALIE3* 

'A ..ie liver of animals. Heace it was 
tMM^ sulpburis^ ** liver of sulphur j'* 
:X9Gfcd ro the air, it soon becomes greco^ 
:«aKe. It is hard, brittle, and has a glassy 
Irs- usee is acrid, caustic, and bitter, and it 
« jrown stain upon the skin. It has no other 
^w. -::.ui that of sublimed sulphur. When exposed 
a a -noieiit hear, the sulphur sublimes, and the potish 
[OS :n a state of purity. This sulphnret converts 
blues to green, and soon destroys them* When 
iirated with charcoal, it dissolves and combines with 

When sulphnret of potash is exposed to the air, or 
wtai it is moistened with water, its properties vtxf 
som change. It acquires a green colour, and exhales 
die odonr of sulphureted hydrogen gas* This change 
is owing to the formation of a quantity of sulphnreted 
hydrogen, in'consequence of the decomposition of the 
Hydrag:!- water. This new-formed substance combines with the 
fJJJ^J/" snlphuret, and converts it inxo hydrogurtttd snlpburtt of 
potash^ which is soluble in water, and has a brownish 
green colour. It may be formed also by boih'ng in wm« 
ter two parts of potash and one part of sulphur. Sul« 
phuret of potash produces no change upon air, but hyw 
drogureted sulphuret gradually absorbs oxygen. When 
inclosed in a vessel with a quantity of air, it soon ah* 
sorbs all the oxygen of that portion, and leaves nothing 
but azotic gas. This fact, whicli was first observed by 
Scheele, induced him to use hydrogurcted snlphuret to 
measure the quantity of oxygen contained in any given 



• Fourcroy, ii. 30?. 



r 

V roT.Asa. XT 

H ponioa of stmosphericair. Hydro^retedsulphurtitift 0«f i ii. 

P capable of oxidizing and dissolving almoit aJl the Bie- 
tall. We are indebled to Mr Berthollet for the first ac- 
curate accoont of the difference between these two sub- 
stances +. 

Potash cannot be combined with phosphorui bj any Anion on 
metbodat present known. But when potash, dissolved f'""P^'"<^'- 
ia water, is heated over phosphorus in a retort, the wa- 
ter is gradually decomposed, part of the phosphorus is 
coavcticd into pho^horic acid, and a great quantity of 
pbospbureted hydrogen gas is etniited, which takes (irc, 
as usual, as soon as it conies in contact with the air of 
tbe atBiMpbere. It was by thb process that Gciigcm* 
bre first obtained phosphureted hydrogen gas, 

0. It does not appear that potash is capable of unitiag. Anion <m' 
with azote, or eren of acting on it at all : but with (^tunjl 
iBociaiic acid it uoites very readily, and forms the com* '*''*' 
ponttd kootm by tbe name of muriate of potasli. 

1. Poiuh does not combine with any of lire metals ; On ractalj, 
Wtt tome of the metals which have a strong affinity for 
czygei), when pat into a solution of potash in water, es- 
pecially if best be applied, are gradoallyoxidi^.ed. This 

is tbe ease with molyhdenum, zinc, and iron. Tin al- 
to is oxidised in a very small proportion 9 and this 
scams also 10 ho the case with manganese. 

It is capable of dissolving a considerable number of And ihcii 
Aa iiMt«Ui« oxides) and in some cases it deprives them '>"*^"' 
of a dote of their oxygen. Thus when poured upon the 
tid oxide of iron, it soon converts it into the black. 
Tbe euse of this change is unknown. It has been aa- 



Sre ain Tromtj /m-. ir Ptjt. 



ttXtIt AUCAUXS. 



ceruinnl, that the oxidct of the bUowing d 
Irnbh ta potufa : 



Zinc, 

Antimonjr, 
TelliuiBin, 
TungBen, 
Holfbdcnain. 



Tio, 
Nickd. 
ArMoie, 
Coinlt, 

MuigaoeM, 

But the DBtnrc of ihex sotntioos has not hitherto bec&/^ 
examined with bsjt d^ree of ailentiaD ; thoogh the 
»bJKt is rcmarkabij coiiout, and promiica lo tbiow 

light both npon the naiore of alkalies and metals. 

Various opiniooi have been cnicriaiaed bjr cbcmiM 
reacting the composition of potash. At one time it 
was fashionable to consider azoic as one of iia constita 
ents ; because ibat principle had been detected in aa 
monia, and it vi% thought not unlikely bj Lavoinru 
that as cxjgen, one of ihc coostitucnis of air, was the 
acidi^ng pnnciplc, sule, the otlier constituent, wool 
be found to be the principle of alkalisatioo. MotvcMI 
and Dcsormes anoouoccd, some time ago, that thej| 
consider potash as a compound of hjrdrogen aod Hnci 
Their chief proofs were the appearance of litne, wheft 
the sail, composed of hyperoxygenized muriatic tCiA 
and potash, is uiongly heated with phosphoric acid ia 
a crucible of ptatnium t and a maoifesi combustioD, li 
gellier with ihc deposition of lime, when charcoal at>4 
poUsli arc in like manner exposed to a suong heai^ia k 



• Bcrginui, Ef. «(. ProuEt, /i*t. ii ftji. Irt io;. 



filatiDBncnicible'' Bill these and the other experimcii* CKap-ii. 
tal proofs bring examined by Dacracq, that accuralc che- 
mist ascerlaii>cd that the results obtained bj Deiormes 
sod Morveau were owing, id most cases, to the impurity 
of the pota^ with which they had made their eaperi' 
ni«nu i while ill utiieis they had drawn wrong inferen* 
ces from mistaken resemblances f . Their hypothesis 
of^ctranecaimol be maintained. 

This question, interior to □one in the annals of ch«- Compaq* 
nustryj has been at last decided by the happy sagacity j'™*" ^^ 
of Mr Davy, who has recently enriched chemistry with 
a laag train of the must important and brilliant disco- 
ven«t. Poiash, it follows from his esperiments, is a 
oonpound of »xygen and a new metal, to which he has 
{ivca the Dame oi potaaiuin. 

When potash is ptrfeclly dry ii is a non-conductor of How dc- 
electhcity, bgt it becomes a conductor when Uightly "^'"*"^ * 
mDisteaed on the surface, a degree of moisture which 
it Kqatics by being exposed for a few iccondi to the 
Kunosphcrc. When pieces of potash in this stale are 
f bccd upoD a disc of platinum attached to the nega- 
tive cud of a powerful galvanic battery, and a plaitnum 
-^virv from the positive extremity is made to touch its 
^ppCT surface, the potash is gradually decomposed, 
«xygcn gas separating at the extremity of the positive 
wire, while globules of a white metal like mercury 
appear at the side in contact with the platinum disc. 
A aufliber of accurate experimenia demonstrated to Mr 
Davy, that these globules were the basis of polasli, 
rad thai tbcy were convened into potash by absorbinf 



iJlim.J,Cii-,lllfl.. 



34 



FIX&S ALKALIES. 



Book II. 
DiYiaion I. 



Properties 
of potftf* 
finaL 



• I 



lliq«cific 



Action of 
oxygen. 



oxygen. This metallic substance possesses the follow- 
ing properties : 

Its colour is white like that of mercury. At the 
temperature of 100^ it is as fluid as mercury ; at 00^ it 
still continues imperfectly fluid ; at 50® it is a soft and 
malleable solid, while at 32*^ it is hard, brittle, and 
crystaUized in facets. When heated nearly to redness 
it is volatilized and converted into vapour. It coodttcta 
dectricity and heat as well as other metallic bodies. 

It differs remarkably from all the metals previoualj 
known in its specific gravity ^ being lighter than any 
other liquid substance hitherto examined, swimming 
even in naphtha of the specific gravity 0*710. As it al- 
ters very rapidly wben exposed to the air, it is difficull 
to ascertain its specific gravity with accuracy. Mr 
Davy endeavoured to estimate the relative weight ef a 
globule of potassium and of mercury, of exactly tbe 
same bulk^ measured by means of a micrometer : he 
found the weights to each other as 10 to 223, whi<;h 
gives 0*6 nearly for the specific gravity of potassium* 

Its affinity for oxygen and its tendency to.absorb that 
principle are .much greater than that of any other 
substance previously known. Hence^ if exposed to 
the air, it absorbs oxygen, and is covered with a crust of 
potash in a few minutes -, this crust absorbs water which 
is rapidly decomposed, and in a short time the whole 
becomes a saturated solution of potash. When thrown 
upon water it decomposes that liquid with rapidity^ heat 
is evolved, hydrogen gSL% holding potassium m solution 
is emitted, which takes fire spontaneously, and the 
whole potassium burns with an explosion, and is con- 
verted into potash. It burns equally when placed upon 
ice. It equally decomposes water, and is converted in* 



W> potash when kept in alcohol, eiherj mi oils, or when _ct«p.^ ^ 

thrown into the mineral acids. Newly distilled naph- 

ths is the subiunce in whicli it may be best presemd. 

la this liquid it remains iiiialccred for many days, and 

nay be readily examined in tbe open air when covered 

with a craaiof i[. 

Wticn heated in hydrogen gal, a portion of it is dis- 
solved, and the gas acquires the property of burning 
apontaneouslj when it is mixed with atmospheric tir< 
Boi if kept for a short time it again drposiles the 
poikuiuin, aai loses the property of buraing sponta- 
neously. 

When heated in z small quantity of oxygen gaa it ab- protoiid* 
luta a portion of il, loses its metallic appearance, as- °JP'""' 
wmes a reddish brown colour, and becomes grey when 
coldi In this state it may be considered as a protoxide 
«f potassium. This protoxide may be readily formed 
by filsiog together potash and potassium in a glass tube 
Ullcd with the vapour of naphtha. When exposed to 
the aif it readily absorbs more oxygen, and is coru 
verted into potash. 

When potassium is exposed to the action of oxjmu- 
riaiic acid gas it takes fire, and is converted into muriate 
of potaih. 

Potassium, when brought in contact with phosphorus, nnphiiM, 
and pressed upon under naphtha, combines with it and 
fonns a phosphuret of pMassium, which has the colour 
of lead, and rsmains solid at the boiling point of naph- 
tha. When e^^poscd to the air it slowly absorbs oxy- 
gCD and is converted into phosphate of potash. When 
the meial and phosphorus are brought into contact in 
the epcn air, they become fiuid together, bum, and are 
cottvertcd at once into phosphate of potash. 
C ?. 



AUi.jt. 



30 FIXED ALKALIES. 

BiK>k If. Potassium combines rapidly with sulphur in tubcifilkd 

Division I. , r ^ r 

' V 'f with the vapour of naphtha, while heat and light are evol- 
.-tu p urc . ^^^^ YYi^ sulphnret formed has the grej colour of aitifi- 
cia) sttlphuret of iron. A little sulphureted hydrogen ii 
giren out during the formation of this compound. In 
the open air the combination takes place with combos* 
tion, and sulphuret of potash is formed. Snlphuret of 
potassium, when exposed to the air, is gradually con* 
verted into •uli>hate of potasti. 

Potassium readily combines and forms an alloy with 
aH the mrtals hitherto tried. When oott^ptrt of potaa* 
sium is added to about lo parts of mercury in bnlk, 
they iaitantly unite and form a substance very like 
mercury in colour. When a globule is made to tcmch 
a globule of mercury twice as bulky, they combiae with 
considerable heat. The globule is at first fluids but on 
cooling becomes solid and resembles silver, Jf the po^* 
tassium be increased to about y^th of the awrcury in 
weight, the amalgam is harder and becomes brittle. 
. One part of potassium renders 10 parts of mercury solid^ 
and fortns an amalgam very soft and malleable. When 
these amalgams are exposed to tho air, they rapidly ab- 
sorb oxygen, potash is formed, which deliquesces, and 
in a few minutes the mercury is found pure and unalter* 
• ed. In water the amalgam is decomposed with a hiss- 
ing noise, hydrogen gas is evolved, and the mercury 
remains free. The fluid a^lgam of potassium acts 
upon most metals. In this state of union mercory acts 
on iron and platinum. 

When potassium is healed with gold, silver, or cop- 
per in t close glass vessel, it combines with them* The 
alloy is decomposed when thrown into water, potash is 
formed, and the other metals separated* No attempts 



fOtASK. §% 

have been made to combine it with other metals, except Chap. M. 
with fusible metal, with which it unites and form^ an 
alloj that requires more heat to melt i^ than the fusible 
metal itself. 

When potassium is mixed and heated with metallic ^^^9" ^ 

, . metiUic ox- 

oxides^ It rapidly reduces them to the meuUic state. Mr ides. 

Davy tried the experiment on the oxides of iron, tin, 
and lead* When there is an excess of potassium it forms 
an alloy with the revived metal. Its action upon me- 
tallic oxides is so strong, that it readily decomposes flint 
and green glau in a gentle heat« 

Mr Davy demonstrated by the most decisive expe- ContticiH 
riments, that when potassium combines with oxygen to ^ ^^^ 
saturation it is converted into potash. He performed 
this experiment in glass tubes, and ascertained the bulk 
of oxygen gas absorbed during the combustion of a given 
weight of potassium. From these experiments it fol- 
lows, that potash is composed of about 6 parts potas* 
sium and 1 part of oxygen, or nearly of 

potassium 86 
oxygen 14 

100 

€ralvanism is not the only mode by which potash may Potash de- 
be decomposed, and its base obtained nearly in a state ^y ^"^^ 
of purity. Gay Lussac and Thenard have succeeded 
in decomposing it by i^ans of iron filings ; and their 
experiment has been successfully repeated by Mr Davy. 
Into the middle of an iron gun barrel is to be put a 
quantity of clean and dry iron filings or turnings. An 
iron tube, containing potash as dry as possible, should 
be ground to one end of the gun barrel, and havir^ a 



iron. 



PIZED ALKAJLIES* 

j*^'J- small hole through Tvhich the potash may run slotvljr 
'When Tnelced. To the other extremity a tube of safety, 
containing mercury or naphtha, ought also to be luted, 
ftnd great care should be taken that all the lutings bt 
iiir tight. The gun barrel being laid across a furnace, 
the iron turnings within it are brought to a white heat, 
while the potash is kept cool by means of ice i then 
the potash is brought into fusion^ and made to flow slow- 
ly through the iron turnings. Hydrogen gas is emitted 
in considerable quantity during the whole process. Tlie 
part of the gun barrel next the tube of safety should be 
kept constantly cool. When the process is at an end, 
• portion of potassium nearly pure is found near the tube 
safety; butthe greatest part of it is alloyed with the iron 
turnings *. 

Such are the properties of potassium hitherto investi- 
gated. For all the facts above stated we are indebted to 
Mr Davy f ; but his experiments have been repeated 
and confirmed by other respectable philosophers. Mr 
Davy has lately ascertained that the protoxide of potas* 
slum has the property of combining with ammonia and 
azote. > The last compound inflames spontaneously 
when exposed to the air, potash is formed, and azotic 
gas disengaged. It acts violently on water, and produ« 
jOea* potash and ammonia %* 

Potash or the peroxide of potassium is of the highest 



• HU> Mag, mii. Sp, and 176. See il«o 1 note iti Mr Da^y^t f apcr 
Cfflltf Dtfmfmitkn 9jtiM. Kartbt. PUL 7 rami, 1 80S. 

f Sec Divy'i lecture on the DecLm^> titUn ami Cmf0,iti$$n/Ue Fintd 
ties. P . 'I raits J l8o8« 

I fl^ M^. Ulii. 36S 



y- 



80DA. 39 



hupoHance, not only in cbemistrj, where h is emploj- . Chap» n. 
cd for a great variety of purposes, but also in manj 
aru and mannfacturet ; as washing, bleaching, djeing^ 
glass-making, and others, as will afterwards appear. 
It is employed also in surgery and medicine. 



- - ■ 



SECT. n. 



OF s e B A. 



Soda, called ulso Jhssilor minef-al aUali*^ because it N«»«% 
was thought peculiar to the mineral kingdom, was 
known to the ancient^ (though not in a state of purity) 
under the names of *'^r^ and nitrum f . 

It is found in large quantities combined with carbo* Pr«P«^a. 
nic acid in different parts of the earth, especially in £• 
gypt ; and common salt is a compound of soda and mu- 
riatic acid. But the soda of commerce is obtained from 
<he ashes of different species of the salsoia^ a genus of 
plants which grow upon the sea-shore, especially from 
the lalsola sodoy from which the alkali has obtained its 
name. The soda of commerce is also called barilla^ 
because the plant from which it is obtained bears that 
name in Spain. Almost all the alga?, especially the 



* Dr Pearson has proposed to distinguish it by the rMxytoifostalUH; 
KUproth calls it matro». 

f The x.7p9v of t e Athenians wa^ evidently the same substance; aad 
» tns the nr.) of the Hebrews. 



4b 



FIXED AUSALVLB. 



Book 11. 
DiTiBion I. 



iFhypertiei. 



fuciy conUiQ also a considerable quantity of soda. The 
ashes of these plants are known in this coontry by the 
name of ie/p ; in France they are called varf£. 

The soda, or barilla, of commerce, is fiur from being 
pure ; besides carbonic acid it contains cooimoa salt^ 
and several other foreign ingredients ; but it may be ob- 
tained perfectly pure by the processes described in the 
last Section for purifying potash. 

Soda and potash resemble each other so nearly^ that 
they were confounded together till Du Hamel publish- 
ed his dissertation on common salt in the Memoixt^ 
the French Academy for 1736. He first proved that 
the base of common salt is soda, and that soda is diflRcr- 
ent from potash. His conclusions were objected to by 
Pott, but finally confirmed by Margrafifin 1758 *• 

Soda is of a greyish-white cdour, and agrees exactly 
witli potash in its taste, smell, and action upon animal 
bodies ; but its specific gravity is only 1*S$6 f • 

Heat produces on it exactly the same effects as upon 
potash. When exposed to the air, it absorbs moisture 
and carbonic acid, and is soon reduced to the consisW 
encc of paste : but it does not liquefy like potash ; in • 
few days it becomes dry again, and crumbles into 
powder. 

It has a strong affinity for water, dissolves in it like 
potash, and may also be obtained in crystals by evapo- 
rating its aqueous solution. It is not altered by light ; 
nor does it combine with oxygen, hydrogen, azote, car- 
bon, charcoal, nor metals. Its action upon phosphorus 
aild sulphur is the same with that of potash. The suU 









y 



♦ O^Mtc, ii. 331. 



t HasKiifriti, Amk. dt Cbim. sxviii. 11 



Compcni' 



|)l>UMt ud hjdroguieted eulphutet oi soda pouess the cin^U-^ 
properties of the sulphuret and lijdrogureied siilphuret 
of poauh, ami are formed in ihe same manner. In its 
Kiion on meUls, metallic oxides, and in its afKnities, it 
aho agrees with potash. In short, the two iixed alkalies, 
ui a state of purity, resemble each other very neatly io 
almost every particular. 

Similar apinioos respecting its composition 
IcftaiDcd by chemists, as those whicii they had respect- 
iag the composition of potash. Fourcroy supposed it a 
compound of magnesia and az.ole. Desnrmes and Mor- 
v-CBU *, on the other hand, aflirmed that it is composed 
of magnesia aud hydrogen ; but tlie experiments upoji 
wbtcb tilts opinion was founded have been proved in- 
accurate by Darracqf. Mr Davy has lately succeeded 
in decomposing it by the vame processes which enabled 
him to ascertain the composiliou of potash. Like that 
alkali it is a metallic peroxide. To its metallic basis 
Mr Davy has given the name oi sodium. 

Soda ii decomposed by tiie galvanic battery in the 
, mae v/^y as potash ; but requires a more powerful 
battery, or much sroaJlcr pieces of soda must be exposed 
t» iu aciKiD> 

Sodium is a white metal like silver, and at the c 
iDontem]>erattire of the atmosphere is solid; butexceed- ' 
ingly malleable, and so soft ibat pieces of it may be 
welded together by strong pressure. It still retains its 
malleability and softness at the temperaiure of 32". 
When heated to l^o" it begins lo melt, and is com- 
fjki^J fluid at 180° i though exposed to a red heat 



t ^*.i^CM>. 1I.171. 






4t 



nXED AtKALttS. 



Booktt. 
IKvition I. 



•i^gmSaf. 



strong enough to melt plate glass, none of it is Irolatilj- 
ted« 

It conducts electricity and heat in the same manner 
as potassium. It is heavier than that metal, though not 
fo heavy as water ; swimming in oil of sassafras, of the 
specific gravity 1*006, and sinking in naphtha of the 
specific gravity 0'861. By mixing these two liquids 
together till they acquired just the specific gravity of 
sodium, Mr Davy ascertained that the specific gravity 
of that metal is 0-9348. 

Its aflinity for oxygen is similar to that of potassium, 
and hence it acts nearly in a similar manned when ex- 
posed to substances containing that principle. When 
exposed to the air it absorbs oxygen, and is soon cover- 
ed with a crust of soda, which deliquesces much more 
slowly than potash ; hence the sodium is not so soon 
converted into an alkali as potassium. No combustion 
takes place unless the sodium is heated nearly to redness; 
but the rapidity of the absorption of oxygen increases 
with the temperature. The flame which it produces in 
oxygen gas is white, and as it sends out bright sparks 
the effect is beautiful. 

Hydrogen gas though assisted by heat seems to have 
no action on it whatever. When thrown into water so- 
dium occasions a violent effervescence, with a loud hiss- 
ing noise ; hydrogen gas is evolved and soda formed ; 
but no combustion takes place as happens to potassium, 
probably because sodium is insoluble in hydrogen gas. 
A few scintillations indeed appear when sodium is 
thrown into hot water. Sodium usually burns also 
when brought in contact with a small particle of water, 
or when placed on moistened paper. 

Wbea fused with dry soda in certain quantities, there 



14 ft dtvision of oxygen between the soda and (lie base ; Chip. IL^ 
and a protoxide of sodium is formed of a deep brown 
colour while fluid, but which becomes a dark grey solid 
oa cooling. This protoxide when exposed to the air 
abMrbs oxygen, and is converted into soda. 

When sodium i* exposed to ihe action of oxyrauria- 
li« acid gas, it burns vividly with bright sciTiiillalions 
of a red colour. 

Il combines with phosphorus with the same pheno- Ptio^hn- 
nena as potassium, and forms a similar phosphuret, '^*^' 
irhicb is convened into phosphate of iioda by exposure 
uthc air. 

It combines with sulphur in close vessels filled with Snlphnret. 
the VDpouT of naphtha with great vividness, with light 
and heat, and often with eiiplosian from the vaporiza- 
tion of a portion of the sulphur, and the disengagement 
of sulphuTeied hydrogen . The sulphuret of sodium is 
of a deep grey colour. 

Il decomposes (he wnicr in alcohol and ether precise, 
ly aa potassium does. In oils it gradually absorbs oxy- 
gen and forms soaps. It is converted into soda, when 
thrown into the mineral acids, in nitric acid with in* 
Sunmation, and in sulphuric and muriatic acids with 
the evolution of much heat. 

It combines with metals, and forms alloys similar to AIIoja 
the alloys of potassium. One part of it renders 40 
puts of mercury solid, and of the colour of silver ; and 
the combination is attended with a considerable degree 
of beat. Jt combines with tin uriihoui changing its 
colour, and acts on gold and lead by the assistance of 
heat. When these alloys are exposed to the air the 
lodiDm soon absorbs oxygen, and tsconveilrd intofodt; 



44 FIXED ALKAUES. 

Book H. the amalgtm of sodium combines with the other me* 

* y ■> tals and with sulphur, forming triple compounds. 

Compoti- From a number of experiments on the. combination 

tion MKia. ^ sodium with oxygen, made in the same manner as 

those on the combination of potassium with the same 

principle, Mr Davy has shown that soda is composed 

of about 7 parts sodium and 2 of oxygen, or nearly of 

Sodium 78 
Oxygen 22 



100 



Thus it appears that both the fixed alkalies are metallic 
peroxides, and that the bases of both are capable of com- 
bining with two doses of oxygen* But the protoxide 
is not permanent in consequence of its great affinity for 
oxygen. 

The importance of soda in manufactures is not infe- 
rior to that of potash. For several purposes, indeed, as 
for the manufacture of soap and glass, it answers even 
better than potash. 



ALKALINX £AftTK8A ^ 



Chip. Iff. 



as 



I 

CHAP. m. 

OF THE ALKALINE EARTHS. 



' i . 



in word Emth, in common ^ langnage, has two 

meaniogt ; it sometimes signifies the gloiif which wififl* 

habit| and sometimes the mould on which vegetables 

grow. Chemists have examined this mould, and have 

found that it consists of a variety of substances mixed 

together without order or regularity. The greatest 

part of ity however, as well as of the stones which form 

apparently so large a proportion of the globe, consists 

of a small number of bodies, which have a variety of 

common properties. These bodies chemists have agreed 

to class together, and to denominate earths, 

£very body which possesses the following properties 
ift maeartim 

1. Insoluble in water, or nearly so ; or at least beco* 
tuing insoluble when combined with carbonic acid. 

2. Little or no taste or smell ; at least when combi* 
tied with carbonic acid. 

3. Fixed, incombustible, and incapable while pure of 
being altered by the fire. 

4* A specific gravity not exceeding 4*Q. 



4a XLKAtlVK EA&THS. 

Book IL 5. When pure, capable of assuming the form of a 
tHtluon r. , . , 

ivhite powder. 

6. Not altered when heated with combustibles. 

The eartlis have been divided into two classes, name- 

ly, alkaline earths and eartbs proper. The first have the 

propertj of giving a green colour to vegetable blues, 

and of neutralizing acids ; the second do not alter ve« 

getable blues, and are incapable of neutralixing adds* 

The alkaline earths are four in number ; namdy. 

Lime, 

Maokesia, 

Barytes, 

Stromtiak. 

The properties of these bodies occupj our attenligft 

in the four following Sections. 



SECT. I. 



OF LIME. 



Ijime has been known from the earliest ages. The an* - 
cients employed it in medicine ; it was the chief ingre« — 
dient in their mortar ; and they used it as a manure to^ 
fertilile their -fields. 

Lime abounds in most parts of the world, or perbaps^^ 
I should rather say, that there is no part of the worldL 
where it does not exist. It is found purest in lime- 
stones, and marbles, and chalk. None of these sub-^ 
stances, however, is, strictly speaking, lime ; but tbey 
are all capable of becoming lime by a well-known pro* 



tess, by kcepiog them for some lime in a white heat : Ctap. lU. 

thii process is called the hurmnj of iimi. The product, : 

which in comcnoo language is denominated quicklime, 
is ihc lubiUQCc known in chemi&iry by the name of 
Uxu. 

1. Lime may be obtained perfectly pure by burning Prqjatif • 
those crysla)liz,ed limestones, called cakarccau tpars, A 

which are perfectly white and transparent, and also by 
burning some pure white marbles. It may be procured 
also in a state of purity by dissolving oyster-shells in 
muriatic acid, filtering tlic solution, mixing it with 
ammonia as long as a white powder continues lo Call, 
and filtering again. The liquid is now to be mixed 
'with a solution of carbonate of soda ; the powder which 
falls being washed and dried, and heated violently in s 
platinum crucible, is pure lime. 

2- Pure lime is of a white colour, moderately hard, PfopettJEj, 
but easily reduced to a powder. 

It has a hot burning taste, and io some measure cor- 
rode* and destroys the lexmre of rhose animal bodies 
to which it is applied. Its specific gravity is 2-3 ■. It 
liitgei vegetable blties gieen, and at la^t converts them 
to yellow. 

It is incapable of being fused by the most violent 
best that can be produced in furnaces, or even by the 
most powerful burning-glasses. 

3. If water be poured on newly burnt lime, it swells sbtkJnjiif 
and falls to pieces, and is soon reduced to a very fine "*"■ 
powder. In the mean lime, so much heat is produced, 
that part of the water flies ofi* in vapour. If the quan- 



48 ALKALINE EARTHS. 

^^^" ; tity of lime slacked (as this process is temted) be great, 
^ » -' the heat produced is sufficient to set fire to combusti- 
bles. In this manner, vessels loaded with Ihne have 
sometimes been burnt. When great quantities of lime 
are slacked in a dark place, not only heat but light al* 
so is emitted, as Mr Pelletier has observed *• When 
slacked lime is vreig^, it is found to be heavier than 
il was before. This additional weight is owing to the 
combination of part of the water with the lime ; which 
water may be separated again by the application of a 
red heat ^ and by this process the lime becomes just 
what it was before being slacked f • Hence the reason 
of the heat evolved during the slacking of lime. Fart 
of the water combines with the lime, and thus be- 
comes solid ; of course it parts with its caloric of flui* 
dity, and probably also with a considerable quantity of 
«-, • . caloric which exists in water even when in the state of 
ice : for when two parts of lime and one part of ice 
(each at 32^) are mixed, they combine rapidly, and 
Hydnieof their temperature is elevated to 212'*. The elevation 
'"^ of temperature during the slacking of barytes and 

strontian is owing to the same cause. From the ex- 
periments of Mr Dalton it follows, that slacked lime, 
well dried in a moderate heat, is composed of 3 parts 
lime and I part water t* This result does not differ 
much from the previous experiments of Lavoisier, who 
found that 1000 parts of lime, when slacked, were con- 



• /Mir. tfV Pbyx. i. «. f Dr Black. 

I Daltno's Srw Sy:Um •/ Cicm'uat PiiUttfly, i. 87. 



««rtrd into 1287 parts*. SUdced limi then ma; be 
cMu^lcrcd as a hydrate o/limt. 

Tli« smvll perceived during the slacking of lime is 
owing lo « part of thai carlli being elevated along wiih 
ifao vapour of the waiet ) as cvidcDtly appears lioin 
this circumslunce, that vegeuble blues exposed to this 
Vftpour Bie convened Into grern. 

Limestone and cliaik, though ihejr are capable of be- 
ing converted into lime by bumittg, possess hardly any 



of the properties of that 
latleUss, scarcely soluble ii 
Itbly act oil animal bodies, 
properties of lime owing I 
dcrgo in the 6re? 

It had been long kjiou 



live substance. They are ' 
I water, and do not peicep. 
Now, to what are (he new 
What alteration does it uo- 

that limestone loses a good 



deal of weigh thy betog binned oc calcined. It was na- 
fural to suppose, tlierefore, that something is separated 
firotn it duriog ciUitiJiion. Accordingly, Van Helmont, 
X.udovicus, and Macquer, made experiments in tucces- 
. saioo, in order to ducover what thai lemtlliag is ■, and 
r %hey concluded from tliem limt it h pure water, which 
I «helime recovers again when exposed to ihc atmosphere. 
As lite new properties ol lime could hardly be ascribed 
I to this loss, but to some oilier cause, ^tahl's opinion, 
like all ihe other chemical theories of that wonderful 
mm, was ^em-rally acceded lo. He supposed that the 
new properties which lime acquired by calcination are 
owing enlirely to the more minute division of its parti- 
cles by the action ofllie fire. Boyle indeed had en- 
deavoured to prove, that these properties are owing in 



ar.t'sltij bj Henry, p. 130. 



?r'- r. •▼ 



§6' ALKALIS E EAATR6. 

fopk ir. tliijBcation ofjlre in the lime ; a theory which Was ctil^ 
braced bj Newtoa and illustrated bjr Hales, and whidr 
Meyer new modelled, »nd explained with so much in^ 
gennity and acuteness as to draw the attention of the 
most distinguished chemists. But while Meyer wat 
thus emplbyed in Germany, Dr Black of Edinburgh 
published in 1756 those celebrated experiments which- 
form so brilliant an era in the history of chemistry.* - 

He first ascertained, that the quantity of water sept^ 
rated from limestone during its calcination b aol nearljf 
^tfiA to the weight which it lost. He ooodndcd in 
cottseqnenee, that it must have lost something else than 
-mere water. What this could be^he was mt fim at ft- 
loss to conceive ; but recollecting that Dr Hales had 
IMTOTcd thai limestone, during its solutioa in acidsr 
emits a great quantity of mr^ he conjectured that iHt 
might probably be what is lost during calctnatien. He 
oalriaed it accordingly, and applied a pneumatic appa- 
ratus to receive the product. He found his cou je c tu ro 
verified ; and that the air and the water whiah separa* 
ted from the lime were together precisely equal to the 
loss of weight which it had sustained. Lime therefore 
owes its new properties to the loss of air ; and lime- 
stone differs from lime merely in being combined with 
m certain quantity of air : for he found that,- by restoring 
again the same quantity of air to lime, it was converted 
into limestone. This air, because it existed in lime in 
a fixed state, he called^#^ air^ It was afterwards ex. 
amined by Dr Priestley and other philosophers ; found 
to possess peculiar properties, and to be that species 
of gas now known by the name of carbonic acid gas. 
Lime then is the simple substance, and limestone is 
composed of carbonic acid and lime. Heat separates 



USE. 51 

the ciiboitic add, and leaves the lime id a state of Chip , ul 
jwritjr. 

5. Wfaeo lime is exposed to the open air, it gradu- 
ally attracts moisture, and falls to powder ^ after whicb 
it sooa becomes saturated with carbonic acid, and is 
agsin Converted into carbonate of Lime or uaburnt lime- 
•tone. 

Wxer, at (he common tempcratute of the atmosphere Action «l 
dtisolvea less tbas 0*002 pans of its weight of lime". "*""" 
ThU soluiiaa is called Unu-iuater. It is limped, has an 
acrid taste, and changes vegetable blue colours to green. 
One ounce uoy of lime-water cotitains about one gciiii 
of lime. it is usually formed by throwing a quantity 
«f Uate in powder into pure water, allawiag it to ic* 
maia for some time in a dose vessel, and then decant- 
ing the nansparcnt solution from the undissolved lime. 
WbcD lime-water it exposed to the air, a stony crust 
UOD forms on its surface composed of carbonate of 
ItOM i wben this crust is broken it falls to the bottom, 
lad uiothex succeeds it ; and in this manner the whole 
of the lime is soon precipitated, by absorbing carbonic 
acid from the air. 

6. Lime is not acted on by light, neither does it com- 
\iaa with oxygen. 

7- Sulphur and phosphorus are the only simple com- Of umboc' 
btuiiblea with whicb it tmiies. 

Sulpburet of lime maj be formed by mixing its two Sttlpbuiar- 
compoaent parts, reduced to a powder, and heating 
ibcn to a crucible. They undergo a commencemcst 



* By Btf uiili, Uaie mier mocmh obI; eae 7jlth of iu^wtigh; oE 
D s 



twining the phosphorus remain t cold. When the lime Chir* ilL 
becomes red hot, raise the tube, and draw it along the 
eoals till that part of it which contains the phosphorus 
is exposed to a red heat. The phosphorus is immedi- 
ately volatilized, and passing through the hot lime 
combines with it. During the combinAtion the mass 
becomes of a glowing red heat, and a quantity of phos- 
phureted hydrogen gas is emitted, which takes fire when* 
it comes into the air. This curious process was contri- 
ved by Dr Pearson, to whom we are indebted for the 
discovery of the earthy phosphurets *. 

Phosphuret of lime has a deep brown colour,^ and is 
moulded into the shape of the tube. It lias no smell, 
and falls to pieces in the air. It is insoluble in water ; 
bat it has the property of decomposing that liquid. 
Phosphureted hydrogen gaa is emitted, which takes fire 
as soon as it comes to the surface of the water. Part 
of this gas combines with the phosphuret, and forms a 
kind of tiydrogureted phosphuret. Hence it happens^ 
that if phospuret of lime, after being kept for some time 
in water^ be taken out and dried, it flames when muria« 



* Van Mods las proposed the fonnwing method ; but it appears to 
me railier inferior to that which is described m the text : — Fiil a tmall 
gbsa matran two-thirds with carbonate of lime in powder. Put it Snt* 
a nod bath, and expose it to a heat suffidem to drive off the carbonic 
acid. Towards the end ol the process introduce gradually a third pare 
«f phosphorus, taking care to keep the lime in a red heat. The phoa- 
phoms rocks bat is prevented from burning by the remains of carbonic 
acid, which it dist-ngages from the lime. When the whole of the phos- 
pl oms is introduced, shut up the matrass with a stopper, provided with 
a valve to let gas escape, but pcrmiting none to enter, and let the fire be 
immediatdy withdrawn. When quite cold, the phosphuret is to be pnc 
trto dry phiait with ground stoppcn. Sec Jmr, dt dim. iiL 75. 



54 ALKALIS£ EA&THS. 

Bor.k 11. tic Mid is pcmred upon itf owiog to the rapid emisiloa 

*mm y of phof phurcted hydrogen gts *• 

8. Lime does not combine with aiote i but it unites 
readilj with muriatic acid^ and forms muriate of lime. 

Action of 9* Lime facilitates the ozidizement of several of the 
metals, and it combines with several of the metallic 
oxides, and forms salts which have not hitherto been 
examined, if we except the compounds which it Ibntts 
with the oxides of mercurj and lead, which have been 
described bjr Berthollet. 

And thdr The red oxide of mercury, boiled with lime-water, 
A% partly dissolved, and the solution yields by evapora- 
tion small transparent yellow crystals t* This eom* 
pound has been called by some nurcuriaU ofUme. 

Lime water also dissolves the red oxide of lead, and 
(still better) litharge. This solution, evaporated in a 
retort, gives very small transparent crystals, forming 
prismatic colours, and not more soluble in water than 
lime. It is decomposed by all the alkaline sulphates, 
and by sulphureted hydrogen gas. The sulphuric and 
muriatic acids precipitate the lead. This compound 
blackens wool, the nails, the hair, white of eggs ; but 
it docs not affect the colour of silk, the skin, the yolk 
of egg, nor animal oil. It is the lead which is precipi- 
tated on these coloured substances in the state of oxide ; 
for all acids can dissolve it. The simple mixture of 
lime and oxide of lead blackens these substances a 
proof that the salt is easily formed $• 

10* Lime does not combine with alkalies. 



a Foorerajr, u. 171. t Berthollet, Jmm. A Chm. 1.61 

} Berthollet, M», dtCUm. 1. js. 



II. Oiie of the most important uses of lime is the for- plur.i n. ^ 
oiation of mortar as a cement in building. Mortar is Mortar, 
composed of quicklime and sand reduced to a paste with 
water. When drj it becomes as hard as stoae, and as 
datable ; afld adhering very strongly to the surfaces of 
the stones which it is employed to cement, the whole - 
wkU becomes in fact DOlbing else than one single stone. 
But this dTcot is produced verj impcr&cllj unless the 
mortar be very well prepared. 

Tbc lime ought to be pure, completely fioe from 
oibonic acid, and in the state of a very line powder: 
the sand jhould be free from cl3.y, and partly in the 
state of line sand, partly in that of gravel : the water 
ibould be pure ; and if previously saturated with IJme, 
ao much the better. The best proportions, according 
•to the experiments ofDr Higgins, are three parts of 
fine sand, four paruof coarser sand, one pail of quick- 
Lime recently slacked, and as little natcr as possible. 

The stony consistence which mortar acquires is owp 
ing, partly to the absorption of carbonic acid, but prin- 
cipojly to the combination of part of the water with the 
lime. This Ust circumstance is the reason, that if to 
eoauDon mortar one fourth part of lime, reduced to 
powder without being slacked, be added, the mortar 
when dry acquires much greater solidity than it other- 
wise would do. This was first proposed by Loriot * ; 
and a number of experiments were afterwards made by 
Morvcau f . The proportions which this philosopher 
found to answer best are the following. 



f^ ALXAtnrS SA&THS. 

^?«*"; Fine tand 0*S 

D171H00 f. 

Cement of well baked bricks.. 0*8 

Slacked lime 0*2 

Unslacked lime .••• 0*2 



1-0 

The tame advantages maj be attained by using as 1 
water as passible in slacking the lime. This was 
pointed out by La Faye *• 

Higglns found that the addition of burnt bones 
proved mortar by giving it tenacity , and renderin 
less apt to crack in drying ; but they ought newi 
exceed one fourth of the lime employed. 

When a little manganese is added to mortar, it 
quires the important property of hardening under 
ter ; so that it may be employed in constructing t 
edifices which are constantly exposed to the actic 
Water. Limestone is found not unfrequently comb 
with manganese ; and in that case it becomes brow 
calcination, instead of white, lliese nati^'e Itmest 
tre employed for making water mortar ; but good 
ter mortar may be made by the following process, 
proposed by Morvcau : Mix together four parts of 
elay, six parts of black oxide of manganese, and 90 ] 
of limestone, all in powder. Calcine this mixtui 
expel the carbonic acid, mix it with GO parts of s 
and form it into mortar with a sufficient quantit 
water f. 

The beat mortar for resisting water is made by 1 
jng with lime puzzollano, a volcanic sand brought i 



f }]M' ia* 437* f -^m. tf^ Ciiw, xuth. 259. 



Italj". Morvpau informs usthat inW/M, which Uvery Ch»p.lti. 
common in this country, may he siibsiituicd for piiz- 
zoHado. It must be healtd in a furnace, thrown while 
red-hot into water, and then passed through a sieve to 
reduce it to the proper sixe *. 

12. Wrth respect to the composition oflime,nothing but Airempti 
coi^CCture was known till lately. From the theory of [lowfrnJ^ 
Beccherand Siahl, it was the general opinion of chemists 
ihtt ihc earths and metallic oxides are of a similar na- 
ture. Neuman, in consctjiience of an experiment of 
Healcel, aitcmj^ied to obtain a metal from chalk by 
heatingii along with combu&iibie substances ; but bis es- 
perimenit did not succeed f . The idea, however, was 
001 abandoned ; for it was a favourite notion of Lavoisi- 
er thst nil the eatlhi migb; be metallic oxides I. About 
[ ihe yetr 1790, soon alter ihc publication of Mr Lavoi- 
r ritrf'a book, Mr Tondi and Professor Ruprecht, both of 
iScbcmnitz, announced that they had obtained from 
'bttrytes, by a strong Ileal, a metal which ihey caUed 
'Asr^Miim, of the colour of iron, and attracted by the 
KiHigacl i from magnesia anoiher, which they call aus- 
Mrvtn : a third from lime, also called autlrum ; and a 
tfouith from allumina, which ihey denominaied apuium. 
Their fncthod of prccuding was to opp'y a violent heat 
TOT (be earlhs, which were surrounded with charcoalin a 
Hessian crucible, and covered with calcined boneii in 
powder. Bm these experiments were soon after repeat- 
ed by Klaprolh, Savoresi, and I'ihau^ki ; and these sc- 
cnnte cbenisls soon proved that the pretended mciab 



A Ctim. iiivi;. iSj. t Ltwis, A'.Tioun'j Cinrlifr; . ]■. !«. 

p. SI7, E'zUii JrnHil. 



^g ALXALINS lAJinS. 

Book H. wer-e all of ihcm fbosphurtu of irmt, Thtt irofiy faj tbc 
t^ y viplenoe of the heat^ hid been extracted from the cnu 

cible, and the photphorus from the bonet. 

Still more late] j Desormes and Morveau were led to 
infer from some experiments, that lime is composed of 
carbon, aLote, and hydrogen, and magnesia of lime and 
azote *• But the experiments of Dorracq have demon- 
strated that the results obtained bj these chemists weie 
owing to the impurity of the substances on which tbcf 
operated f* 
IlL*^- ^' Davy's discovery, that the fixed alkalies are 
«^«« tallic ozides» naturally led to the conclusion tha^ the 

kaline e^hs which resemble them so closely are ti 
lar compounds. He accordingly exposed them in va* 
rions states to the action of a galvanic battery, and 
reason to conclude that his opinion of their nature 
cormt, though he found it much more difficult to de 
compose them and obtain their bases, than it had 





to obtain potassium and sodium by similar procesaes, 
When acted upon undjcr naphtha they were not distinct 
ly decomposed. When fused with an excess of pot 
ash, and acted upon in that state, the results were r>t 
ther moredistincty metallic substances appeared leas fuai^ 
ble than potassium, which burnt the instant after they^ 
were formed, and produced a mixture of potash and the 
earth employed* When the earths were exposed to the 
action of electricity, mixed with the oxides of mercury, 
tin, lead, or silver, amalgams were produced, which ex- 
hibited propertiesindicatingunequivocally, that they were 
mixtures of the base of the earth employed, and of the 



* Mem.dti InttiL iii. jax. f Am, dt Cbim. sl. 171 



UME. 

baMofthemelallicoxide mixed with it. fiat the qauitU <^b*i>-tn. 

tf of amalgam obtained wns too miouic to adroit of an 
■ccorate rxauiDation . While Mr Drvj was engaged 
ia these experitnenis, he receiveda letter from Professcr 
Betzcliiii of Slockholm, informing him, that he and Dr 
Pocttn bad tucceeded in decomposing barjtes and lime, 
by negatively el ecirifjing niercury in contact with lhcm> 
Mt Davy immediately repeated this happy experiment, 
SImI succeeded completely in obtaining amalgams of the 
1»sc of the earth employed. 

To procure thtse amalgams in sufficient quantity for 
distilling oif the mercury, and obtaining the base of the 
earth pure, Mr Davy combined his own previous me- 
thod with that of Beritlius and Pontiu. The earth was 
(lightly moistened, mixed with one third of red oxide 
nf mercufy.and placed upon a plate of platinum connect- 
ed with the positive end of the battery. A cavity was 
made to the earthy mixture, a globule of about 60 grains 
of mercury put toto it, and this globule connecicd with 
the negative end of the battery by a platinum wire. 
The amalgams obtained in this way were distilled in 
glass tubes filled with ihe vapour of naphtha. The 
greater part of the mercury was easily driven oS^ bat 
it was extremely difHcuIt to separate the whole. The 
globole that remained behind was in all cases white 
like silver, solid, and extremely combustible. When 
exposed lo the air it absorbed oxygen, and regenerated 
the earth &om which it was obtain- d in a few minutes. 

The metallic basis of lime Mr Davy has called caA Cilci'um 
ram. He did not succeed in investigating its proper- '" "" 
tics. It is white like silver, solid, and probably 4 or 8 
times heavier than water. When heated in the open 
■ii it bnnti briUiantly, and quicklime is produced. 



fO AtKALlVZ EARTHS. 

BaiA 11 Neither did Mr Davy succeed in his attempts to aseer* 
tain the proportion of the constituents of liroe, though 
be was satisfied that calcium by absorbing oxygen is 
converted into lime *• 



SECT. II. 



OF MAGNESIA. 

Hirtorj. A.BOUT the beginning of the eighteenth century^ 
Koman canon exposed a white powder to sale at Ro 
as a cure for all diseases. This powder he called mhg* 
tuna alba. He kept the manner of preparing it a pro 
found secret; but in 1707 Valentini informed the pub* 
lie that it might be obtained by calcining the lixivium 
which remains after the preparation of nitre f ; and two 
years after, Slevogt discovered that it might be prccipi- 
Sated by potash from the mother Icy % of nitre §. This 
powder was generally supposed to be lime till Frederic 
Hoffman observed that it formed very different combi- 




* Davy*! EltctroihmLal Retearcbes om tht Jgfmftjiticm •/tie gartii, \^t. 

f Dg Afajmnh yilha, 

% TKc matter ity is r]ie Ik^uid that riinaini after at much aappiilble oT 
aay ^e hai been obraincd irom it Cunimon ult, for in>tfai)cc» it ob* 
uincd by cvapurating icu-watcr. After at much salt has liren eitracted 
from • quantity of sca-wati-r ai will crystallize, there is still a portion of 
liquid nmaining. This )>«)rtion is the mcther Irr. 



Itioos wiih other bodies". Bui little was known Cha p. itL 
■nccfni&g its iiKlure, and il vm even confounded with 
mcliy ino» chemists, till Dr Black mode his celebrated 
IperittMntB on it in 1755. Margraff published a dis- 
pnation on it in 1 15m t, and BergmaD another in m5» 
I which he colkcied the observations of these two 
pUoaophcrs, and which he mriched also with muiy 
|lditioas of his own X. Buiini of Geneva likewise 
^blishcd a valuable dlisertation on it in 1719. 
p I. As magnesia has never yet been found native ina^'f*'^ 
Ittcof purityi il may be prepared in the following nnan- 
fer: Swipbate oj magiujia, a sale composed of this earth 
fti sulphuric acid exists in sea-water, and in many 
Lrings, particularly in some about Epsom ; from which 
pcuroitancG it ws« formerly called £pioHi laii. This 
U| it IQ be dissolved in water, and hnU' its weight o£ 

Plh added. Tlie magnesia is immediately precipi- 
, because potash has a stronger afiinity for aulphu- 
Lib acid. It is then to be washed with a suffideat quan- 
mj of water, and dried. 
L s. Magnesia tbu^ obtained is a very soft white pow- ptDpcrcici- 
Itr, which has very little laite, and is totally destituie 
■ smell. Its specific gravity is about 2*3 j. It con- 
trts delicate vegetable blues (paper, for instance, stain> 
P with the petals of the mallow) to green. 
It is not melted by the strongest heat which it has 
:a possible to apply ; but Mr Djroet observed that, 
1^ a very high temperature, it became somewhat tgglu- 
^led. When formed into a cake with water, anl 



• Oil. Mjt.CNm.tjii,f- 105.1 



f Kirwan'* Mimr. i. t. 



62 ALKALXKE KAtTHS. 

pwl^^. ^^^ exposed to a Tiolent heat, the water it graduallj 
driven off, and the magnesia cootracts in its dimensioa ; 



at the same time, as Mr Tingry informs os, it 

the property of shining in the dark when rubbed upoi 

a hot iron plate. 

^^^^^ S. his almost insoluble in water: for, according 
to Mr Kirwan, it requires 7900 times its weigkl 
of water at the temperature of 60^ to dissolve it. It ii 
capable, however, of combining with water in a solid 
'^ state, like Ume; for lOa parts of oiagaesiay thrown 

iaio water, and then dried, are increased in weight U 
118 parts'*. Even when combined with cariioaic aoil 
(for which it has a strong' aflbiity) it is capable Of ab 
soffbing and aeteining 14. times its owb weight of watei 
without •Mtting go a drop ( but on -exposure So the air, 
this wmter-evaporates, thongh more slowly than it woiH 
from lii^ew 

• Magnesia has never yet been obtained in a eryatili 
lizedfdlrm. 

When exposed to the air, it attracte carbonic acid gai 
and water ; bnt exceedingly slowly. Butini left a quan* 
tsty of it for two years in a porcelain cup merely oo< 
vcred with paper ; its weigbt was only increased ^ 
part. 

Oxygen, 4. Magnesia does not combine with oxygen, nor ii 

it altered by any of the compounds into which oxygei 
enters; 

simole 5. The only one of the simple combustibles wiA 

combmciP y/fY^]^ i| ^n be united is sulphur. No person has hi- 
therto succeeded in forming a phosphuret of magnesia. 



O JkifinaD.t. 37r. 



MAGKXSlJl.' €3 

M 

la tins icsped it differs from the other three atkaluie Clay. Hi. 

earths. 
The sttlphturet of magnesia maj be formed by ezpo- 

ibg m mirture of two parts of magneaim and one part of 

idphnr to a gentle heat in a crucible* The result is a 
yellow powder, slightly agglutinated, which emitt very 
Bttk solphureted hydrogen gas when thrown faito wa» 
ler, A moderate heat is sufficient to drive otff* the saU 

e. Magnesia does not eombine with axele^ but it iconbnitl- 
vdles with muriatic acid, and forms a compound cal- ' 
kd mariai€ of magnesia. 

7. Magnesia has no action upon the metals; nor Metals, 
iot% it combine, as far as is known at present, with tlie 
metallic oxides, unless some intermediate substance be 
piesent. 

8. Magnesia does not combine with the fixed alkalies. Alkalies* 
seither are its properties altered by these bodies : but 

it has a strong propensity to enter into triple compounds 
tvith ammonia^ 

0. Mr Kirwan has shown that there is but little af« 
iuty between stroatian and magne«a» They do not 
^elt when exposed to a strong heat, at least when the 
^trontian exceeds or equals the magnesia f. 

Equal parts of lime and magnesia, mixed together, 
iKud exposed by Lavoisier to a very violent heat, did not 
ckielt ; neither did they melt when Mr Kirwan placed 
Uicm in the temperature of 150^ Wedgewood. The 
following Table, drawn up by Mr Kirwan from his own 



• roarcroy, n. 165. f Irish Trtuu. r. 246, 24 r 



04 



ALltAtXirE EARTHS. 



BooV \u experiments, shows the effect of heat on these two earths ! 
mixed together m dinerent proportions* 



Propnrtiont. 



80 Lime 
20 Mag. 

75 Lime 
25 Mag. 



66 Lime 
33 Mag. 



20 Lime 
80 Mag. 



33 Lime 
66 Mag. 



30 Lime 
10 Mag. 



Hett. 



150^ Wedg, 



160 



165 



138 



156 



Effect. 



Vl^'ent through the cmcibk. 



Went through the crucible. 



Went through the crucible. 



Did not melt. 



Did not melt. 



Melted into a fine greenisbl 
yellow glass ; but the crucible) 
was corroded throughout. 



Decompo* 
•iti«u ti 



Magnesia is used onlj in medicine. It is admini- 
stered internallj to remove acidity in the stomach. 

Magnesia, like lime, is a metallic peroxide. ATx 
Davy succeeded in decomposing it by the same proces ^ 
by which he decomposed the other alkaline earths —- 
When moistened magnesia is exposed to the action o^ 
galvanism in contact with mercury, the earth is reduced^ 
and its base amalgamated with mercury much more 
slowly than the other alkaline earths ^ owing probably 
to its insolubility in water. The process succeeds much 
more rapidly when moistened sulphate of magnesia is 
substituted for the pure earth. To the base of magne- 




ioed, Mr Davy has given the name of maj- 
i« s white solid itieial, hiving ihe appearance 
.\vtr J sinks rapidly in waier, and of course is con- 
tderably heavier tlian thni liqiiiil. When the amal- 
m of magnium is distilled in a glass lube filled with 
e vapour of naphtha, the meial appears to act upon 
e glass before the whole of the niercury is separated 
Mn it. Of coarse it is diiScult to obtain it in a stale 
puriiy. When e:tposcd to the air it rapidly absorbs 
:ygen, and is convened into magnesia. It decom- 
ttn water, separating the hydrogen, and combining 
Pttb the oxygen ; but not nearly so rapidly as the 
ther merals Obtained froiA the alkaline earths ; owing 
loubiles* to the insolubility of the magnesia in water. 
t when the water is acidulated with sulphuric acid, 
dei»in position of water and the formnioa of mtgne- ' 
goes oa with great rapidity * 



OF BARTTE3. 



lAkfxES Was discoveretf by Schecle in ITTij ittiithe ( 
fU itcceuni of lis properties published by him in his 
tisurtalion on Mangancie-f-, There is a very heavy 

iiDcrailt mo»( frequcbtly oTa flcsli culour, of 2 fbliud 



It A-t frmi. iScS. 

t BAcclt. ■. £t Hid 7I. Fnndi Ttiaslaci 



ftf Dtamfuilm tfti* SjT*tt, 



tioo. 



AS ALKAUNX EJdlTBS. . 

Book IT. texture and briiile, very common in Britain and mo$t 

DtvitiiNi l« , 

Other countries, especially in copper mines. It wat 
known by the name o£ ponderous fpar, and was supposed 
to be a compound of sulphuric acid and lime. Galu 
analyvd this mineral in 1775, and discovered that uia 
ooroposed of sulphuric acid and the new earth diaoovcr- 
ed by Scheele *• Scheele poblished an account of the 
method of obtaining this earth from ponderoua spar f • 
Xhe experiments of these chemists were oonfiroMd by 
Bergman ty who gave the earth the name of tnmfm 
derasa^ Momeau gave it the name of iarafw, and Kis- 
wan of hary^s^ ; which last was approved of hj Baif* 
{pan ||)» imd is row ttoiversally adopted. DiSoseatpfls* 
ceases for obtaining barytes were pabliahed bj Seboak^ 
Bergman, Wiegleb^ and Aiswelius y but littla addiciida 
wa^mAde to. the pcopertiea aaoBrtained fay tha osigiail 
discoverer, till Dr Hop^ puUtshed his ezpeaasBats is 
17Q3 ^. In 1797, our knowledge of its nature wis 
still &rther extended by the experiments of Pelletier, 
Fourcroy,,and Vauquclin**.. 
Prepara- ^^ Barytes may be obtained from ponderous spar, or 

sulphate ofharytes^ as it is now called, by the followin|^ 
process, for which we are indebted to Scheele and Van- 
>quelin . Rednce the mineral to a fine powder ; mix it 
wit]i the eighth part of its weight of charcoal powder^ 
and keep it for some hours red hot in a crucible, and 
it will be converted into sulphurct of barytes. Dissolve 
,lhe si\Iphuret in water, and pour nitric add into tbe 



.* «« a M 



« Bergman*! Notes on Schcffcr, { 167. 
a^&<M^i4«MJ:>, iiL 3. Bag^TtMi. % O^tuuvL S91. 

§ From fi«f vf , heavy. g Ofmc^ iv. a6r. 

^ BJin, rr«M. iv. 36«. ::f s 4mu ^t Clim,.i»L 113 aad S^i* 



BJUtXTXS. ;«1 

snd the sulphur will be precipitated. The so- ^Clup. III.^ 

hicii considis of nitric acid combiacd wiib ba- " » 

Kjrtes, is to be Altered and evapoTBted klow]^ bU it cr}'s- 

•iiliscs. Put the cr;&ials into a crucible, and expose 

»m graduKllj to a strong hot i the nitric >cid is dli- 

o off, uid the barytes remains in a state of purity '. 

Anolfasr method, attended wiifa less expcnce, was 

liatod wit long ago by Dr Hope, and afterwards im- 

prottd by Pclkiicr. The method is this ; Dccoiuposr 

sulpbtte of barytes by heating ii strongly along 

^th charcoal powder. The product is to be treated 

iti) mter to dissolve every thing that it soluble ; and 

le liquid, being filtered, is to be mixed with a solution 

pC arboDstc of soda. A white powder falls. Wash 

powder, make it up into balls with charcoali and 

il stroogly in a crucihlt. When these balls are 

buicd with boiling water, a portion of barytes is dis- 

nhrcd, which crystallizes as the water coob, 

2. Barytes obtained by the first method is a greyish- ftoff^- 
arbite, porous body, which may be very easily reduced 
It has a harsh and more caustic tatte than 
^nte t >Bd when taken into the stomach proves a roo&t 
pioknl poison. Il has do perceptible Binetl. It tinges 
vcgcnble blues green, and decomposes animal bodies 
Kke the Axed alkalies, though not with such energy. 

Its specihc gravity, according to Fourcroy f, is 4^ but 
IGcordiog to Hassenfratz only a-3t4J;. But there is 
to conclude, from the method employed by lhi« 



WlHn tfan* prepved, it ■!«»;■ coataiwtbou 008 o( <wbaaHi of 

♦ t^uaaj, ii 189. 1 An. Jt Ctm. ntiii. 1 1, 

E 2 



m 



ALKA&XNX IJIRTRB. 



BookTT. 
XXrittoo f. 



Action of 



philotopher, that the specific gravities whfch he assigns 
are' all too low. 

When heated it becomes harder, and acquires inter* 
nallj a bluish^green shade. When exposed to the blow- 
pipe on a piece of charcoal, it fuses, bubbles up, and 
runs into globules, which quickly penetrate the cbafw 
coal *• This is probablj in consequence of containiiif 
water, for Lavoisier found barytes not affected bj the 
strongest heat which he could produce, 
't When exposed to the air, it immediately attradi 
moisture ; in consequence of which it siwells^ heat 19 
evolved, and the barytes falls to w white powder, jiiit 
as happens to quicklime when water is sprinkled on itf; 
After the barytes is thus slacked^ it gradually attracts 
carbonic acid, and loses its acrid properties, ita weight 
being increased 0*22 %• It; cannot therefore be kept 
pure except in close vessels. 

'3. When a little, water* is pomved up«n barytes, it 11 
slaqked like quicklime, but more rapidly,- and with the 
evolution of more heat. The mass- becomes wfaitep aoi 
swells considerably. If the quantity of water be aofr * 
oient to dilute it completely, the barytea cryatallixea ia 
caolmg, a!id asauises the appearance of a atone ooospo* 
sad of needle«form crystals ; but when exposed to tbt 
air, it gradually auracu carbonic acid, and falls to pow« 
der $• ' 

Water is capable of dissolving 0*05 parta of its 
weig^ of barytes. This solution, which is kndwn hf 
the name of barytes water, is limpid and colourless, has 



^ Wmrm t j tiut Viu^ndia, Amm» 4$ CUm, xxl 176. 

f Id. ibid. ii. 59. t Mtmnk i' Imtiii. & 5> 

{ Fdnreniy, ii; 192. 



^n ^crid taste, and converls vegetable blues first to a ' 
greni, and then destrojs them. When exposed lo the 
air, m surface is soon covered with a stony crust, ton- 
listing of the barytcs coaibined wiih carbonic acid. 

Boiling water dissolves more than half its weight of 
btrywi. As tlie solution cools, Ihe barbies isdeposited 
in crystals i the shapeof wbicli varies accordiug lo the 
»pidity withwhith tlkey have been formed. When 
most regular, they are fiat hexagonal prisms, having 
two broad sides, with two intervening narrow ones, antt 
terminated al each end by a four-sided pyramid, which 
in tome instances constitutes the Jarger part of the crys- 
tal. When formed slowly they are distinct and large ; 
4ut when the water is saturated with barytes, they are 
deposited rapidly, and are .generally more slender and 
delicate. Then, too, they are attached to one another 
in such a manner as to assume a beautiful fnliacwus 
appearance, not unlike the leaf of a fern ". 

These crystals are transparent and colourless, and 
appear to be composed of about 53 parts of water and 
41ofbarylcs. When exposed to ihc heat of .boiling 
water, tbcy undergo the un/oj /j/z/ony that is to say, 
tbe water which tliey contain becomes sufiificnt to keep 
die baryies in solution. A stronger beat makes the wa- 
ter fly off. When exposed to the air, they attract car- 
Iwnic acid, and crumble into dust. They arc soluble, 
in n-J parts of water at the temperature of GO" ; but 
boiling water dissolves any quantity whatever; the 
reason of which is evident ; at that temperature their 
Awn water of crystallization is sufficient to keep them 
in solution |. 



• Hope, £■!(. Tun,.. 



I 

^9 ALKALiys XAILTHSf 

Book j^ 4. Barytcs undergoes no change from light ; neitber 
< J ■> is it capable^ as far as is known, of combining with 

Action of -»^««^., 

^tygeo. oxygen. 

Of the liia- 5. None of the simple combustibles combine with Hf 

{ibloK""' «3ccept sulphur and phosphorus. 

Sulphuret of barjtes ipay be formed bj mizmg its 
two ingredients together and heating them in a cmoible. 
The mixture mehs at a red heat, 9nd when cold fimns 
A mass of a reddish-yellow colour, without anj am^ll| 
which is su^hiret ofharytet. This sulphnret decom- 
poses water with great rapidity ; sulphureted bydrogeti 
is formed, which, combining with the sulphuret^ con* 
verts it into a hydrogureted sulphuret. This change 
takes place whenever the sulphuret is moistened with 
water, or even exposed to the i^tzposphere. 'Wbea 
boiling water is poured upon sulphuret of bsfytet, % 
great quantity of sulphureted hydrogen is formed al- 
most instantaneously, which combines with the water^ 
and occasions the solution of the sulphuret. When the 
^lution cools, a great number of brilliant white crys- 
tals are deposited, sometimes in the form of needles, 
sometimes ia six-sided prisms, and Sbmetimes in hexa* 
gonal plates. These crystals are composed of snlpbi- 
reted hydrogen and barytes, and haye been called by 
Berthollet, to whom we are indebted for the first accBv 
rate account of them, hydrosuipburet of barjtet. The 
liquid which has deposited the hydrosulphuret is of a 
yellow colour, and holds in solution a bydrogttrtted swlU 
phtret ofbarytes *. 

^'"••I*"* Phosphuret of barytes may be formed by pisttiog 

^ phosphorus and barytes into a glass tube dose at one 



a Berthollet, Aiuuig Cbim. nv. 133. 




' XUITTIS. 

^tld, lad Iwuing the lube upon burning coals, aa in 
jvuking pbosphurct of lime. The combination takes 
l{4>]aoe vcf jr rapidly. This phosphur«t is of i dark brown 
i«Dlour, Tcrj briUiiint, and very fusible. When moisten- 
ed, it exhales ihe odour of phosphureted hydrogen gas. 
When thfown inio water, it is gradually decomposed, 

iMphorcied hydrogen gas is -emitted, which takes lite 
;l|vliea it comes to the surface of (he water, and the 

loapbora* is gradually convertrd iato pboaphoric 

id". 

fi. Barjtcs is not acted on by axole; but it com- ;; 
'tiaes rekdily ^vithmDriaticacid, and forms « compound i 
jicillcd mariatr qfiarytn. 

7. Barytej has no action on metals ; but it is capable | 
contbiaiag with aeveral of the nieiallic oxides, and ' 

inning with them compounds which have not hilherio 
•.a moch exammed. For instance, if it be poured into 

Bolutiao of silver or lead in nitric acid, it pn-ci pi tales 
kbK 6rK brown, and the second white ; but if sn excess 
of barytei water be added, (he precipitates arc /edi»- 
Bolv«dt- 

8. Barytei does not combine with Ac alkalies. • 
O. We are indebted to Bucholz for a aet of experi- 

oa the action of barytes on the other earthy bo- 
Lime does not seem to imiM with it. When 
t({nal quxntitics of the two earths are heated in a cru- 
tiUCi a mass is obtained, having some cohesion, but so- 
iubte in water I- The phenomena were nearly the 



Smuaaf, ii. 1 91. 

ud Vuiqoclin, Mim. i, FttitU. <l. (<%. 
' BUlTtp, ill. j9. He leaDi not to hiv 
W( a labiiniriiu. 



^2 ALKALZKE EiJlTBS. 

^^\m\ **^"^ when barytes and magnesia were heated together. 

* V ■' When ihc resulting mass was treated with water, the 

barytes dissolved, but took up more of the magnesia *. 

Comtita- 10. Barytesylike the other, alkaline earths, has been de» 

cats of ba- 

^yies. monstrated by Mr Davy to be a metallic peroxide. To 

the metal which constitutes its base, the name oi ioH^ 

um has been- given. Mr Davy succeeded in obtaining 

this metal, by placing a misturc of barytes and oxide of 

mercury in coiiuct with a globule of mercury^ and ex* 

posing it to the action of a galvanic battery. The ba^ 

^ytes was decomposed, and its base amalgamate^ wAk 

the mercury. The amalgam was then heated in a glai^ 

tube filled with the vapour of napl)|tba, to drive Oiff th^s 

mercury. Barium, thus obtained, is a solid metal o^ { 

^ the colour of silver, it melts at g tcipperature belot 

redness, and is not volatilized by a heat capable of mell 

ing plate glass, but at that temperature it acts yiolentl, 

upon the k:Iass; probably decomposing the alkali of 

glass, and converting ti into a protoxide. When expose -d 

to th^ air it rapidly tarnishes, absorbs oxygen, and 

converrcd into barytes. It sinks rapidly in water, 

seems to be at least four or five times heayier than tha 

liquid. It decomposes water with great rapidity ; hy 

drogen is emitted, and it is converted into baryu 

When strc ngly pressed it becomes flat, and hence aj 

pears to be both ductile and malleable. The propp/ 

tion of oxygen necessary to convert baripm into bsury te^^ 

has not been asccrtainedf. 





• BurholzV ^ehrfs^e, iii. p. 56. 

f- lJavy*d E't'Jro^- im'ical Ktitarclet en the Dteem^MiUm rf tie Karttim ... 
?M. Trans. t8oS. 



:>#nioirTiAK. 




SECT. IV, 



QF STROKTXAK. 



r the year 1*787 a mineral was brought to Edin- Htatf. 

bj a dealer in fossils, from the lead mine of 
in, in Argyleshire, where it is found imbeded 
3re» mixed with several other substances. It is 
nes transparent and colonrless, but generally has 
of yellow or green. Its hardness is 5* Its spe- 
ravity varies from' S'4 to S'720. Its texture is 
ly fibrous ; and sometimes it is found crystalU- 
slender prismatic columns of various lengths *• 
I mineral was generally considered as a carbonate 
tes ; but Dr Crawford having observed some dif- 
s between its solution in muriatic acid and that 
teSy mentioned in his treatise on muriaie of hary^ 
>lished in 1790, that it probably contained a new 
md sent a specimen to Mr Kirwan, that he might 
le its properties. Dr Hope made a set of expe- 
( on it in 179 1» which were read to the Royal 
* of Edinburgh in 1792> and published in the 
ctions about the beginning of 1794. These ex- 
nts demonstrate, that the mineral is a compound 
onic acid, and a peculiar earth, whose properties 



• Hope, Edln, Iranu iv« 44. 



.•" 



t!oo. 



M ALKALIKC EAWfjA. 

Book It are described. To this earth Dr Hope nvt the name 
oiitrontius. Klaproth analysed it also in ITOd, and 
drew the same conclusions as Dr Hope, though be was 
ignorant of the experiments of the latter, which remain* 
ed still unpublished. Klaproth's experiments were pob« 
. lished in Crell's Annals iofz 1793 * and 1794t. Kirwaa 
also discovered the most interesting peculiarities of this 
new earth in 1703, as appears bj his letter to Crdl, 
though his dissertation on it, which was read to the 
Irish Academy in 1794, was not puUiahed till &195* 
The experiments of these philosophera were repeated 
and confirmed in 1797 by Pelletier, Fourcroy, and 
Vauquelin ^ and several of the p ro p er ti es of the eerth 
still fisrther investigated* To the earth thus delceled 
Klaproth gave the name of MtrwUum^ from the 
where it was first found \ and this name is new 
rally adopted. 

Strootian is found abundantly in difienat placet of 
die worlds end always combined with carbooio add or 
aelphmric add« 

freptn- 1« '^^'^ carbonic acid may be expelled fifom the car- 

bonate^ and the strontian obtained pure, by mixing the 
mineral with charcoal powder, and exposing it to a heat 
*of 140^ Wedgewood J ; or by dissolving the mineral in 
nitric acid, evaporating the solution till it crystalliaeay 
and exposing the crystals in a cruciUe to a red heat till 
the nitric acid is driven off. Strontian may be ebtaiaed 



« Vol. ti. 189. 

f Vol i. 99. See also Klaproth*t Beitrage, i. a6o. and Jttr, de ilCW. 
No. V. p. 61. 

t AMHmie Cbm, zzi. II3. imd I76. four, Jt Min. An. ▼?. 5. 
$ Kirwan. 



STROKTUV. •n 

from the sniphate by following exactly the process de- Ch«p. irt 

scribed in ihe list SM:tion for obtaining barjics. 

3. SiroDttan, thus obtained, is in porous masses, qC a Prnputia. 
greyiah white coluur ; its taste is acrid and alkaline; 
and it converts vegetable blues to green. Its specific 
gravity, according to Hassenfraiz, is l'64'I *. It does 
not act so sliongly on animal bodies as barytas, ner b 
it poisonous f. 

It does not tnett when heated, like barytet ; but bc- 
fioR the blowpipe it is penetrated with light, and sur- 
rounded with a 6an)e so white and brilliant that the eye 
can tcsicely behold it J. 

3. When water is sprinkled on stroolian it is slacked, Aciion of 
becencs hot, and tails to po^vder ex^icily tike barytes ; *""'■ 
bot it is not so soluble in water as that earth. One 
hundred and sixty-two parts of water, at the ien)pera< 
tor* of go", dissolve nearly one part ot uramian. The 
sotatioii, known by the name of strontiait vjotir, is clear 
and transparent, and converts vegetable bluet lo a green. 
Hot water dissolves it in much largei quantities; and 
aa il cools, the strontian is deposited in colourless trans- 
parent crjrstals. These are in the form of thin qua- 
drangular plates, generally paraUelograms, the largest 
of which Getdom exceeds one-fourth ot an inch in length. 
SometiiDes their edges arc plain, but they ofiener con- 
sist of two facets, meeting together, and forming' an 
angle like the roof of a house. These cryslah general- 
ly adhere lo each other tn such a manner as to form a 
thin plate of an inch or more in length and half an inch 



» Aim. A Ctim. XTfUl t 



t PcUcCier, Itrid. nlllOi 



n» 



AUALIKE EARinS. 



Book II. 
Divitton I. 



Of osygcDg 

Of oomViiB* 
tiblei. 

Gulphinet 



ret. 



Action of 
•ncooibufr- 
tiblcK, me- 
tals, aod al- 
ftaXku 



in breadth. Sometimes they assume a cubic form. 
They contain about 63 parts in 100 of water. They 
are soluble in 51*4 parts of water at the temperature 
of 60^. Boiling water dissolves nearly half its weight 
of them. When exposed to the air, tliey lose their wa- 
ter, attract carbonic acid, and fall into powder *• Their 
specific gravity is 1*46 f. 

4. Strontian is not acted on by light ; neither does it 
•oombine with oxygen. , 

6. Sulphur and phosphorus are the ooly simple coiu 
bttstibles with which it unites t* 

The sulphuret of strontian may be made by fiisiag 
.the two ingredients in a crucible. It is soluble in viu 
ter by means of sulphureted hydrogen, which is evol- 
ved. When the solution is evaporated, hydrosu^Imnt 
of strofuian is obtained in crystals, and bydrcgmrettd 
sulpbuTit remains in solution. These three compotmds 
resemble almost exactly the sulphuret, hydrosulpburet, 
and hydrogureted sulphuret of barytes; and do not 
therefore require a particular description. The same 
remark applies to the pl)osphuret of strontian, which 
may be prepared by the same process as the phospha*- 
ret of barytes §. • 

6. Strontian does not combine with aiote ; but &1 
unites readily with muriatic acid, and forms the safa^<- 
stance called muriate of strontian. , 

7. Strontian lias no action upon metals; but itcofliK- 
bines with several of their oxides, and forms compouoA: 
which have not hitherto been examined. 



* liopc, Edln. Trtmt. iv. 44- f Ha^anfratz, j1iiii,tU dim xrrlii. X x. 
t Vauquclio, Jour, de Min, An. vi. i;. f IlucU 



s. It does not combine wiih alkalies nor with barj- ' 
tea. No p{<Ecipiiation takes place wlicti barytes and 
DlroRtian waier are mixed logciher *. 

9. Strontiao has the properly of tinging ilame of a 1 
beautiful red, or racher purple colour ; a property dis- 
covered by Dr Ash in I7S7. The experiment may be 
made by putting a litile of the sail composed of nitric 
icid and stroncian into the wick of a lighted candle f ; 
or by setting fire to alcohol, holdmg muriate of strontiaa 
involution. In both cases the flame is of a lively purple. 
In this respect it differs froos barytes, which when tried 
ia the same way is found to communicaic a bluish yel- 
low tinge to the flame %• 

Barytes and sironliau resemble each other lo tbeir 
propetties as closely as potash and soda : hence, like 
ffaesc two alkalies, they were for some time confound- 
ed. It is in their combination with acids that the most 
bUikisg differences between these two earths are to be 
observed. 

Sirontian, like the other alkaline earths, has been de- ' 
«:oinposed by Mr Davy, and by ■ similar process. The 
xnetallic bases of it has been called strontium. It is 
-«rhiie, solid, much heavier than water, and bears* close 
resemblance lolarium m its properties. When expo- 
sed to the air, or when thrown into water, it rapidly 
absorbs oxygen, and is convened into sCrontian }. 



■ Morveau, /bn. it Cb\ 
I Viu<]uclin, Jm. it M 

Ekanehimtt, 

7»». lies. 



■/ Ru,. 



i 



Tt EARTHS fJlOrU. 

BooklL 

himmoDlm 



asaif 



CHAP. IV. 



OF THE EARTHS PROPER* 



a^mi 



The Eanhs proper m diittngubli«l tnm tte Mm 
Km bj neither producing anj change oft vegetable blua^ 
flor aeouatifting acids. Indeed some of them scareely 
«Mle to these bodies. The earths proper aee fieo in 
ftttmber^ namdj, 

Yttria, . 

Glucina, 

ZlRCOKIA, 
SiLIOA. 

We shall examine their properties in the foUowiog 
Sectiofis* 



SECT. I. 

or ALUMINA. 



^^^'^f^* Alum is a salt which was well known to the ancients, 
and employed bj them in dyeing, bat .they were ]gno« 
rant of its component parts. The alchymists discovered 
that it b composed of sulphuric acid and an eartb ; bot 



the natore of (his earth was long unknown. Stahl and ,^*P' ^\ 
Utamxa supposed it to be lime; bat in 1727 Gea£. 
fro; junior proved this to be a mistake, and demonstra* 
ted, that the earth of alum constitutes a part of cla; *, 
fn 1734, Margrafi* showed that the batis of alum is an 
^Bafth of a peculiar nature, difierent from crerj other ; 
lU cscth witucb ik an esscoiial ingredient in days, and 
^jires them their peculiar properties +. Hence this earth 
. wu called argij ; but Morvcau afVerwaids gave it the 
DUna of oiumiiM, because it is obtained in ibe stale 
^cfgrcuest purity from alum. The properties of alo- 
JUaa wete still farther examined by Macquer in 1753 
pul 1702 J, \>y Bergman in i767 and 1771 1|, and by 
Scfaccte in 1716 $ ; not to mention several other che- 
taivte^who have coolributed to the complete investiga. 
t\oa of this earth. A verj ingenious treatise on it was 
P^ublisbed by Saussure junior in iSOl ^. 
, i. Alauinamay be obtained by thefollowing process: Prepar*- 
S)i&solve alum in water, and add to the solulioD ammn- 
pia as long as any precipitate is formed. Decant oiT 
nhe Quid part, and wa&h the precipitate in a large quan. 
^tiiy of water, aod then allow it to dry. The substance 
. tliu) obtained is alumina i not however in a slate of ab- 
I soUue purity, for it still retains a portion of the sulphu- 
, ric add with which it was combined in the alnm. Bm 
it may be rendered tolerably pure by dissolving the 
newly precipitated earth in muriatic acid, evaporating 
the solution till a drop of it in cooling deposits small 



>. ftr. 17a;. f Jtfwi. trrlii, I7J4 md »7J9. MargraflT. ii.. I. 
I 4Jfi»ftrb. !1 Bcrgmui.i.iS^.ud v.Tt. 

^ i. 191. Prmch T^n.I * /jm A Ky..lii.i(:. 



^ 



•0 



EARTHS PIO^M. 



Bookn. 
Diviiioo i. 



ftopertici. 



crystals, setting it by to cry ttallizcy separating the tr) 
tals, concentrating the liquid a second timp, and aep 
rating the crystals which are again deposited; By tli 
process most of the alum which the eanb retained wi 
be separated in crystals. If the liquid be now mizi 
i^th ammonia as long as any precipitate appears, tb 
precipitate, washed and dried, will be alumma nciri 
pure *. 

The earth thus obtained assumes two very diSera 
appearances according to the way in which the preci^ 
tation has been conducted. If the edrtby ^t be dii 
solved in as little water as possible, the alumina bai tl 
appearance of a white earth, light, friable, very spong] 
and attaching itself strongly to the tongue, In dii 
atate Saussure distinguishes it by the name of ipm^ 
abtfmna* 

But if the salt has been dissolved in a great quantil 
of water, the alumina is obtained in a brittle transp 
rent yellow* coloured mass, splitting in pieces like n 
sulphur when held in the hand, itsfractnre is smoo 
and -coiichoidal ; it does not adhere to the tongue, m 
has not tlie common appearance of an earthy body, 
this state Saussure gives it the name oi gelatinout-m 
mina f. 

2. Alumina has little taste : when pure, it ha^* 
smell i but if it contains oxide of iron, which it oft 
does, it emits a peculiar smoll wU^n h^e%\\\\iA upc 
known by the name oi tar:hy smcil \ "j'hi-^ '-nidi 
very perceptible in ciii.-uii ci^iys. i ii'j :.;;». .\iiC ^ra' 
tj of alumiaa is 2* co !| . 



e Accitm's Cbcmittr^s 
ISMMwre^ J^ur.dtFh;; 



r. 198 



f /.. 



■.\jr. 



r- 






1.:. i'i:. [1 K.;rvw;»'s j'. •.. - :. X 



xcmrnirx: 

'i. When heat isapplied to alumina it gradually loses ^^■ 
Weight, ill consequence of the evaporation o(a quaiuity Comrai 
et water with which, in its usual state, it is combined ; '' "' 
Utheisune time its bulk is considerablj diminished. 
The spongy alumina parts with its moisture very readi* 
\y, but the gelatinous retains it very strongly. Spongy 
alumina, wlicQ exposed to a red heat, loses 0-33 parts 
of its weight ; gelatinous, only 0*43 -' Spongy alumina 
loK) DO more than USS when exposed to a heat of 
130" Wedgewood ; gelatinous in the same temperature 
loictbat 0*43^5. Yet Saus&ure has shown that both 
ipecies, after being dried in ihe lemperature of C0°, 
contain equal proportions of water *. 

Aluoiina undergoes a diminution of bulk propbrtion- 
tl to ihe heat to which it is exposed. This cunir action 
leeDU owing, in low temperatures, lo the loss of mois- 
tim: bal ID high temperatures it must be owing to a 
DtofC intimate combination of the earthy particles with 
cacli other ; for it loses no perceptible weight in any 
Ictnperature, bowcTer high, after being exposed to a heal 
of 130" Wedgewood f. 

>Ir Wedgewood took advantage of this property of Wedp- 
klumioa, and by means of it constructed an instrument ™,[^^ 
foT measuring high dcrgn-es of heat. It consists of 
.pi«cn of day of a determinate size, and an apparatus 
for racasurtng their bulk with accuracy : One of these 
pieces Is put iuto the fire, and the temperature is esti' 
xzuied by the coatraction of (be piece %■ ^he contrac- 
uoa of the ofay-pieces is measured by means of iwo 



• Jtw. A Pi,.. lil. 187. t IbiJ. 

t ietaiptioa ol thii ihecmomeier in Ptll, Trui. Iiij. 



brass iulc» fixed upon n pUtc. The distance between 
> which u one entieniity is 0*5 inch, and at the otlier ex- 
tremity 0'3 inch, and the rules are exactly 24'0 inches 
ia length, a:id divided into ?40 equal parts, nUed de- 
grees. These degrees commence at the widest end of 
tlie scale. The first of them indicates a red heal, or 
ail'* Fahrenheit. The clay-pieces are snuJIc/Unden^ 
baked in a red heat, and made so as to lit t^ of 
Thejr are nut composed of pure alumina, but of a 
white clay. 

Unfortunately the contraction of these pieces is 
always proportional to the degree of heal to which tb^ 
have been exposed, nor do they torrespoiid exactly with 
each other. The instrtimcDlt notwithstanding, isccr* 
tsinly raluable, and has contributed considei-ably to* 
wards the extension of our knowledge. 

Alumina, when exposed to a very violcni beat, 
duccd by directing a stream of oxygen gas upon 
ing charcoalr undergoes at commence nten I of fauoa, 
is convetled inlu a white enamel, semi transparent, 
excessively hard *. If we put any confideocc in 
calculation of Saussure, the temperature nccsssary fitC, 
producing this effect is as high as 1575" Wedg* 
1«pod+- 

.4. Alumina is scarcely soluble in water, but m 
be diffused through that liquid with great facility, 
affinity for water, however, is very considerable, 
iu usual state it is combined with more than its Oi 
weight of water, and we have seen with what Bbitiaoei 



t /..r, J, Fij-. 1794. 




it retuiu it. £tco this combination of alumina and cha; * IV. 
water is capable, in its usual state of drynes, of absorb- 
ing Si tini«3 it* weight of water, without suffering any 
to drop oot. It retains this water more obstinately 
than any of the earths hitherto described. In a fVeexin^ 
eaU it cootracti more, and parts with more of its water, 
than nty other earth i a circamstanee which is of some 
UBporUnce in agriculture *. 

Alumina has no effect upon vegetable blues. It can- 
not be crystallized artificially, but it is found native in 
bootiful transparent crystals, exceedingly hard, and 
having a specific gravity of 4. It is distinguished in 
tlds state by the name of safypbyr. 

5. Alnmina, a* far as is known at present, is not af- ActioooJ 
ftcted by light, neither does it combine with oxygen. 

0. None of the simple combustibles are capable of Combotii- 
tmtiBg with it. Charcoal indeed combines with H, and ^^*' 
fonns a black, compound f , which is frequently fonnd 
oatinr. 

7. It is not acted on by atote ; but muriatic acid iQcomhu*. 
dissolves it, and forms with it an uncrystallizabte com- 
pound, called muriate of alumina. 

S. It docs not combine with metals ; but it has a MtuB, 
fttroog affinity for metallic oxides, especially for those 
oxides which contain a maximum of oxygen. Some of 
these cooipounds are found native. Thus, the combi- 
nation of alumina and red oxide of iron often occurs la 
the form of a yellow powder, which is employed as a 
paint, and distinguished by the name of ochrt. 

9. There isa strong affinity between the fixedalkalies Alkali, 



'tinnaSMi*tr.i.f. 



t NicholMn'a Jt^nul, ii. i 

Fa 



94 EARTHS PROPER. 

Book II. and alumina. When heated together, they combine and 
JDifiiion I. - , . , t ■ -j 

• form a loose mast without any transparency. JUiquid 

fixed alkali dissolves alumina by the assistance of hea^ 
and retains it in solution. The alumina is preoipitated 
again unaltered, by dropping an acid into the solu- 
tion. This is the method employed by chetnists to pro* 
cure alumina in a state ot complete purity; for alumi- 
na, unless it be dissolved in alkali, almost always re-, 
tfiins a little oxide of iron and son^^ Rcid, which disguise 
its properties. Liquid ammonia is also capable of dis- 
solving a very minute proportion of neftrly precipitaled 
alumina. 

Barytei and 2 • Baryles and strontian also combine with alumins, 
•troDUm, ■' ■ 

^^ both when heated with it in a crucible, and when bou- 

ed with it in water. The result,- in the first case, is a 

greenish or bluish-coloured mass, cohering but.imper* 

fectly : in the second, two compounds areformed^ the 

first, containing an excess of alumina, remains .in the 

state of an insoluble powder ; the other, containing aa 

excess of barytes or strontian, is held in solution .by the 



water *. 



Lime, Alumina has a strong aflinity for lime, ai^ readily 

. enters with it into fusion. The effect of heat onvuriqns 
mixUires of lime and alumina will appear from the foU 
lowing Table f. 



I 



* Vtoqucrn, Ann* Je, Cbim. xxix. 37a Sec alto BucholE'f Btttr^ip vL 
5«- if.-. 

f Kirwan, 1.65. ■ ] : • 



t 



• 



ALUIUKA. 



Proportions. 


Heat. 


Effect. 


75 Lime 
23 Alumina 


150*^ Wedg. 


Not melted. 


66 Lime 
33 Ahimina 


150 


Remained a powder. 


33 Lime 
66 Alumina 


• 


Melted. 


25 Lime 
75 Alumina 


« 


Melted. 


20 Lime 
80 Alumina 


« 


Melted. 




Magnesia and alumina have no action whatever on Magnesia. 

each other, even when exposed to a heat of 1 50^ Wedge- 

'wood t- 

From the experiments of A chard, it appears, that no 
mixture of lime, magnesia, and alumina, in which tTie 
lime predominates, is vitrifiable, except thej be nbarly 
in the proportions of three parts lime, two magnesia, 
one alumina ; that no mixture in which magnesia pre* 
dominates will melt in a heat below 166^ ; that mix- 
tures in which the alumina exceeds are generally fusi- 
ble, as will appear from the following Table %• 



♦ These three experiments were made by Ehrnian : The heat was 
f^Toduced by directing a su*eam of oxygen gai on burning charcoal, aad 
is the mo»t inttnse which it hai been hitherto possible to produce. 

fKirwan'iJI/wr. i,57. llbiO.p.71. , . /.j 



EAATn ftUOtZR* 



BooklJ. 
DivitioB I. 



Cempoit- 

eteiiofaI»> 

mint. 



S Alumina 
2 Lime 
1 Magnesia 



S Alumina 

1 Lime 

2 Magnesia 



3 Alumina 
1 Lime 
H Magnesia 



3 Alumina 

2 Lime 

3 Magnesia 



A porcelain. 



I 



A porcelain. 



Porous porcelain. 



• 



3 Alumina 
2 Lime 

It Ma^mesia 



Porous porcelain. 



Porcelain. 



"TT 






None of the earths is of more importance to m^nkiiki 
than alumina ; it forms the basis of china and stone- 
IH^are of all kinds^ and of the crucibles and pots em^ 
ployed in all those manufactures which require a strong 
heat. It is absolutely necessary to the dyer and calico- 
printer, and is employed too with the greatest advaa- 
tagc by the fuller and cleaner of cloth. 

That alumina might be a metallic oxide was support- 
ed many years ago by Baron, from the resemblance be- 
tween alum and the salts which sulphuric acid makes with 
metallic oxides. Tondi and Ruprecht Announced about 
17 90, that they had decomposed it, and gave to the metal 
which they obtained from it the name of afmbim* Bat 
SUaproth, Savoresi, and Tihauski demonstrated, that 
this pretended metal was only phosphuret of iron. Mr 
Davy's discovery, that the alkalies and alkaline earths 



xre metallic oxtiles, naturally led to the notion that the Oup. IV. 
earths proper are of (he same nature. Accordingly he 
made a number of experimenls on the subject, and has 
rendered the opinion probable, though he has not been 
able to demonstrate it in so satisfitctary a manner 3s could 
liave been wished. When a mixture of potash and alu- 
atina, in & state of fusion in a platinum crucible, in contact 
with the positix'eendof a galvanic battery, isiouchcd by 
8 platinum wire firom the negative extremity, a bright 
combuslioo lakes place, and metallic globules separate 
SDd bum brilliantly onthe surface. The platinum, 
«vhen taken out and freed from the alkali, is surrounded 
'with metallic scales, which burn spontaneously when 
exposed to the air, and which decompose waier with 
great rapidity, producing potash and an earthy matter, 
which was probably alumina. Potassium, amalgama- 
ted with about one third of mercury, was elcciriflud 
under naphtha in contact with alumina slightly moist- 
ened. After an hour the potassium was made to de- 
cocopose water, and the alkali formed neutralized. A 
doodincss appeared, indicating the presence of an earthy 
iubstanc«. Such were the most sucessfiJ experiments 
that Mr Davy was able to make in his allempts to de> 
compose alumina and reduce it to the state of a metal. 
Supposing that a metallic base ciin be successfully ex- 
tracted &om it, he proposes to give that metal ilie n 

of A 



Plil. TrtMi. 180B. 



1^ EARTHS PROfEt. 



Book I/. 
Division (. 

I ■ II ki ■ * 



SECT. JL 



p F T T T R I A- 



HiitofT. »^OME lime before 1"78S, Captain Arhenjus discovered^ 

in the quarry of Yttcrby in'Sueden, a peculiar mineral | 
different from all those dtscribed by mineralogiste. Its 

• 

colour is greenish black, ?tnd its fracture like that of 
glass. It is magnetic, and generally too hard to be 
'scratched by a kiufe. It is opaque, except in small pie- 
ces, when it transmits some yellow rays. Its specific 
gravity is 4'237*. A description of it was published 
by Geycr in 1768 in CrelPs Annals^ZT\di by Rinmah in 
his Miner's Lexicon. Protessoi Gadolin analysed this 
mineral in 1794, and found it to contain a new earth : 
but though his analysis was published in the Stockholm 
Transactions fcr 179*4, and in Creil's Anrah for 1706, 
it was 'some -time bcfcre it drew the attention of che- 
mical mineralogists. The conclusions of Gadolin were 
confirmed by Ekcberg in J 797, who gave to the new 
earth the name of ^^/na+. They were still farther 
confirmed and extended by Vauqiielin in 1800 J, and 
likewise by Klaproth about the same time || ; and £ke- 



• Gidolin, Crcll's ^«/itf/«, I7'.6, i. 313. — Vauquclin, Ann, dc Clim, 
XXX vi. T46. — Klaproth*» Beitragr, iii.jS. 

f CrclPji Annals t 1 799, ii. 6^, | Ann. dc Clim. XXXvi. 1 4 J. 

.[I Ibid, xxxvii. 80. and BrUr.i^r^ iii. 52. 



I .' 



I 



• .y» 



TTTRIA. 99 

WC15 has publisbcd » oew dissertation on Ihe subject in Chajj. XV. 
the Swedish Transactions for 1S02 *■ We may there- 
fore considei ihe peculiar oature of ytliia as sufficiently 
psUblithed. 

1. Hitherto yttria has been fourd only in the bUcIc Prepu*- 
nioeral first anulysed by Gadolin, and hence called Ca- "°''' 
JaJi/ale, in which it is combined with black oxide of 
iron and the earth called silica j and in yttrolanlalilc, 
which from the description of Ekeberg is a compound 
of tantalum and yltria. Both of these minerals occur 
only in the quarry of Ytlerby. From the first, which is 
Ibe most common, the earth may be procured by treat- 
ing the ruineral reduced to powder with a mixture of 
tiiuic and muriatic acids, till il is completely decompo- 
sed ; then filleting the solution, previously evaporated 
nearly lo dryness, and then diluting it with water. Sy 
this process ihu silica is left behind. The liquid which 
psucs tbT0Uf>h the filter is to be evaporated lo dryness 
and the residue heated to redness for a considerable 
time in a dose vessel, and then redissolved in water and 
filtered. What pames through the filter is colourless; 
when treated with ammonia, pure yilria falls. 

S. Yilria thus procured has the appearance of a fine Ptopcrtin. 
while powder,and has ncitiicr taste nor smell. It is not ■ 

mcllcd by the application of heat. It has no action on 
vegetable blues. It is much heavier than any of the 
other earthsi its speciiicgravity, according to Ekeberg, 
being no less than 4'S42. 

It is insoluble in water ; yet il is capable of retaining 
a great proportion of that liquid, as is the case with 






• J.of. A CUm. ;<i. ;S. 



M 



£ARn8 rtOPER. 



Phrutonl. 



Compoai- 
lipo. 



alumina. Klaproth ascertained, that 100 parts ofyt- 
tria^ precipitated from muriatic acid bj amtnoniay and 
dried in a low temperature, lose 31 parts, or mhnost a 
third of their weight, when heated to redness in a cm- 
eible. Now this loss consists of pure water alooe. 

It is not^ soluble in pure alkalies; but it dissolTes 
readilj in carbonate of ammonia, and in all the odier ak 
Icaline carbonates. It combines with acids» and forms 
wiA them salts which have a sweet taste, and at the 
same time a certain degree of austerity. Some ofdiese 
salts have a red colour. Yttria is the only earthy body 
known which has the property of forming coloured sahi 
with acids. 

9, Yttria Is not altered by light, nor is it likdy that 
it combines with oxygen. From the ezperimeots of 
Klaproth, it does not appear to combine readily with 
sulphur I nor is it likely that it unites with any of the 
other simple combustibles. 

We may take it for granted that it is not afifected by 
azote ; but it combines with muriatic acid, and forms 
a salt not capable of crystallizing. Its action on tbe 
metals and metallic oxides is unknown. 

No attempts have been made to decompose yttria. 
But from analogy there can be little doubt that, like the 
other earths, it is in reality a metallic peroxide. The 
experiments of Ekeberg, if correct, may be const 
as' a demonstration of the truth of this opipion. 
he treated yttria with muriatic acid, oxymuriatic add i 
said to have been evolved. 




OF GLUCIMA. 

BE beryl is a transparent stone, of a green colour, 
I B considerable degree of hardness, which is found 
'MxUized in the mountains of Siberia, and in tnaiiy 
icr parts. Vauquelin analysed (his mineral in 170S, 
the request of Hany, to deicnnine whether it was 
med of the same ingredienis with the emerald, as 
luy had conjectured from mineralogtcal consider- 
aas. The result of the analysis was a confirmation 
the suspicions of Hany, and the discovery of a new 
rth, to which Vauqnelin and his ussociaies gave the 
me o! glucina* . Tlie (rxperimenis of Vauqueljn have 
m repeated by Klaproth f and o»her eminent che- 




1. To obtain glocinv pare, the beryl or the emerald, I 
laced to powder, ts to be fused with thrice its weight 

potash. The mass is to be diluted with water, dis- 
ked in muriatic acid, and the solution evaporated to 
yncss. The residuum is to be mixed with a great 
lantiiy of water, and the whole thrown on a filter. 
Ik silica, which cousiitutes more than half the weight 

the itODC, remains behind ; but the glucina and the 
hci cutbs, being combined with muriatic acid, remain 



92 EARTHS PROPER. 

Book II. in solution. Precipitate them by meant of carbonate of 

Oivttion L 

% ^n ■> potash. Wash the precipitate, and then dissolve it in 
sulphuric acid. Add to the solution sulphate of potash ; 
evaporate it to the proper consistencj, and set it bj to 
crystallize. Alum crystals gradually form. When as 
manj of these as possible have been obtained, pour ia« 
to the liquid carbonate of ammonia in excess, then filter, 
and boil the liquid for some time. A white powder 
gradually appears, which is gtudtta. 

Propertiea. 2. Glucina, thus obtained, is a soft light white pow- 
der, without either taste or smell ; which has the pro- 
perty of adhering strongly to the tongue. It has no ac- 
tion on vegetable colours. It is altogether infusible by 
heat ; neither does it harden or contract in its dimen- 
sions, as is the case with alumina* Its specific gravity 
is 2-970*. 

It is insoluble in water, but forms with a small quan- 
tity of that liquid a paste which has a certain degree of 
ductility. 

3. It does not combine with oxygen nor with anj of 
the simple combustibles ; but sulphureted hydrogen dis- 
solves it, and forms with it a hydrosulphuret, similar 
to other hydrosulphurets in its properties f. 

4. Azote has no action on it ; but muriatic acid dis- 
solves it, and forms with it a sweet-tasted salt, called 
muriate of glucina. 

5. Glucina is soluble in the liquid fixed alkalies, in 
which it agrees witli alumina. It is insoluble in am- 
Oionia, but soluble in carbonate of ammonia, in which 



♦ £kcbcrg, Am*, de Cl'im, >liii. 277. f Fourcfey, ii. 159. 



r 



lejpect it agrees with yttria ; but it is about five limes .^'"P* '^■. 
ntofc soluble in caibonate of ammonia than that earth. 

It combines with all the acids, and forms with them 
sweei'iatted salts*, as is the case also with yttria. 

Mr Davy tried lo decompose glucina by the same Conipo«I- 
meacs as have been related in the lirst section of this 
Cbftptcr with respect to alumina. The eSect was the 
same. We have reason therefore to believe that it is a 
netaitic peroxide. Mr Davy proposes lo call its base 
ghichim. 



OF ZIRCOKIA. 



_^V>ioKG the precious stones which come from the island HixocT^ 

iCeylon, there is one called /or^oja or aircon, which is 
"yesiessed of the following properties. 

lu colour is various ; grey, grecnish-while, yellow- 
3(h, [eddiith-brown, and violet. It is often crystallized, 
-eitAcriu right angular quadrangular prisms surmount- 
ed with pyramids, or octahedrons consisting of double 
i)uadrangular pyramids. It has generally a good deal 
of Inaire, at least iniernaJly. It is mostly semiiranspa- 
tent. ' Its hftrdness is from 10 to IS : Its specific gra- 
TJiy from 4-41fi 10 4-7 +. 
Il loses scarcely any of its weight in a melting hei(l j 



"ART 



fiV* 



'^^^'\ Of uLwrom, ^•no inaiv^cd t a ITB©, nMmd thtt 3QQ 
^nA ■^ ■wi vficn issKled brv 

Tfmvi>ct he lame ji ss /M/JBi i; T urn 

r Tos iercxm-ci. -?*vu^ irooMiy -jg :br se aimy^ th> 

prnth* ar a r'ar.Vf lis liscanarjr. ja ltbS hr psUU^ 
^d Ins jnui^sis jr ±e J^ioraM^ MHitfirr jiuml gg^ 
-lie iame isianiL .n viicii le juo i i '^rf ' ed x Inge pnb. 
porion at* srconio, ixgnwaofhm. hama. dnt U nv^ft 
mciuce chemists :u nini ditsr KtBUxmiL v :liK -rnhjiuf. 





* — 

fir.*"**' '^••*'**«Mi '^**'< Iwrtterto !>e«a 

< ibU-, Wittfii r.M «A.4i«^ «4 ppore wiser «a Ae «Ub at 



L^i-^. 



I Amm. ii fMM. Xxi. 72. 

$ Ibid- ftXii l«)l M.J J^JT.Jt Mlm .U. T 9:. 



'A 



95 

potttb is esiracted ; then diasol»c ihc residaom as Cf»f- 1^-^ 

as passible in diliitEcl nmmiic acid. Boil ihe solii- ^M 

1 to precipitate any silica which may have been dis- H 

fed ; then filler, and add a quantity of potash. The ^ 
coma precipitates in the state of a line powder. 

2. Zicrania, ihits prepared, has ibe form of a fine Propcttin 
itc powder, which feels soinewhat harih when rub- 

1 between the fingers. It has neithertasle nor odour. 
ta iufiuible before the blowpipe^ but when heated 
tleatlf in a charcoal crucible, it undergoes a kind oi 
perfect fusion, acquires a grey colour, and sometbing 
the appearance of porcelain. , In ihts stale it is very 
rd, its specific gravity is 4'3, and it is no longer so- 
>ie in acids. 

Zircoiua is insoluble in water ; but it has a consider- 
le a^ity for that liquid. When dried slowly, after 
ing precipitated from a solution, it retains about the 
ird of its weight of water, and assumes a yellow co- 
ir, and a certain degree of transparency, wUch gives 
a great resemblance to gum arabic *. 

3. It docs Dot combine with oxygen, simple combos- 
lies, axotc, nor metalsi but it has a strong aifiatty for 
vcral metalUc oxides, especially for oxide of iron, 
mi which it is very difficult to separate it. 
It is insoluble in liquid alkalies, neither can it be fu- 
d along with them by me:in& of heal; but it is soluble 

alkaline carbonates. 

4. Scarcely any experiments have been made to ascei^ 
in its af&nity for the diSrrent earths. It ii known, 
iwever, thai a mixture of alumina and zirconia is ca- 
lUe of fiuioa. 



• Vdiquelio, A«*. dtVfm 



P6 EARTHS PROPER. 

Bock 11. Zirconia combines with all the acids, and forms salti^ 
< ^ ■ > which hnve a peculiar astringent taste, and are manj 
of them insoluble in water. 

This earth has not hitherto been applied to any use. 
Its scarcity, and the difficulty of procuring it in a state 
of purity, exclude it at present from any chance of be- 
^ ing employed for the purposes of domestic economy. 

CoropoiU The same attempts were made by Mr Davy to de« 

compose zirconia as those made upon alumina and gla- 
cina, and with similar results. The metallic base he 
proposes to. call %irconium. 



SECT. V. 



OF SILICA. 



History. T^ HERE is a .very hard white stone, known by the name 
o£ quartz^ very common in almost every part of the 
world. Sometimes it is transparent and crystallized, 
and then is called rock crystal. Very frequently it is 
in the form of sand. As this stone, and several others 
which resemble it, as flint, agate, calcedony, &c. have 
the property of melting into a glass when heated along 
with fixed alkali, they were classed together by mine- 
talogists under the name of vitrifiabic stones, Mr Pott, 
who first described their properties in 1746, gave them 
the name oi siliceous stones^ on the supposition that they 
were all chiefly composed of a peculiar earth called silU 
ceous earth or silica. This earth was known to Glau- 



.1 



MtiMAs a 



etdribes the method df ofctaining it .* tut !t ^<W7^> 
rfore its properties wrre accurately ascertain- 
roy * endeavoured to pfoVe that it Ibight be 
nto lime, and Pott f and Baumi t that it 
inverted into alumina : but these assertions 
Iby Cartheuserjy Scheele H, and Bergman ^. 
I chemist we arc indebted for the first accu« 
^f the properties of silica **4 

may be obtained pure by the following pf o« Prq»i|ii 
together, in a crucible, one part of pounded 
rtK, and three parts of potash, tfnd apply K 
uit to melt the mixture completely. Dis^ 
mass formed in water, sattirate the potfltsh 
tic acid, and evaporate to dryness. Towards 
the evaporation the liquid assumes the form 
and when all the moisture is evaporated, a 
I remains behind. This mass is to be wash- 
[e quantity of water and dried i it is then si« 
ite of purity* 

, thus obtained, is a fine white powder^ with* Pro^tfef 
aste or smell. Its particles have a harsh feel, 
:oosisted of very minute grains of sand. Its 
vity is 2*66 ft- 

e subjec'icd to a very violent heat without un* 
iy change. Lavoisier und Morveau exposed 
action of a fire main tamed by osygcn gas 
y alteration Xt* Saussure indeed has' sue*- 



»■ ■■ ' 



Pjr. 1746, p. 186. -f Litbogn,^. 3. P«ft 

JrCLym. { Morrr AU. 

c, i. \^l, 

s '^trns Geapomiquttf '773» O^ttsc. v. 59, 
rr. ii. a6 it Kirwun's A/m. i. 101 

de r Eeole Poiytccha. J. iii. I99. 

I. Q ( 



WAtcr. 



•S EARTHS PROrSR. 

^X "' cceded in fusiDg, bj meRns of the blowpipe, a portioil 
of it 10 extremely minute as scarcely to be peroepdbk 
without a glass. According to the caleulation of diia 
philosopher, the temperature ' necessary for pcodvei^ 
this effect is equal to 4043^ Wedgewood. 
Aotionof 3. It is insoluble in water except when newly preci- 

pitated, and then one part of it it soliiUe in 1000 paA 
of water *. It has no efiect on vegetable colours. 

It is capable of absorbing about one-fourth of its 
weight of water^ without letting any drop firom it $ bat 
on exposure to the air, the watav evaporatea vary ic^ 
dilyf. When precipitated from potash by meanief 
muriatic acid and slow evaporaUon, it retaina a coosi* 
derable portion of water, and fonas with it a transpa- 
rent jelly I but tha moisture gradually evaporatea on 
exposure to the air. 

Silica may be formed into a paste with a small qiiaa* 
tity of water ; this paste has not the smallest dnctilitjp^ 
and when dried forms a loose, friable^ and».inooliereat 
massj. 

Silica rs capable of assuming a crystalline form* 
Crystals of it are found in many parts of the worid* 
They are known by the name of raci cryttal, Whta 
pure they are transparent and colourless like glasi: 
they assume various forms $ the most usual is a htxi* 
gonal prism, surmounted with hexagonal pyramids oa 
one or both ends, the angles of the prism correspoaiL 
ing with those of the pyramids* Their hardnes is ve- 
ry great, amounting to 11. Their specific gravity is 
2*053 It* 



* Kirwan*! Mim. i. la f 11h<I- t Siiiccle. 

ii SjrwaaVitfu. i. a4S. 



SItlOA. 

lerc arc two methods of imitating these crystals Ch«j>. 1 
rt. The first method was discovered by Bergman, 
iissolved lUica in fluoric acid, and allowed the solu- 
to remain undisturbed for two years. A number 
jvtals were then found at the bottom of the vessel, 
ly of irregular Sgures, but some of them cabef 

their angles truncated. They were hard, but aot 
! compared in this respect with tock crystal '. 
he other method was discovered by accident. Pro* 
arScigling of Erfurt bad prepared a liquor silicum^ ■! 
;h was more than usually diluted with water, and | 
uned a superabundance of alkali. It lay nndis- 
ed for eight years in a glass vessel, ihe mouth o£ • 
ch was only covered with paper. Happening is ' 
: to it by accident, he observed it to contain a nam- • 
of crystals ; on which he sent it to Mr Tromms^ 
\ professor of chemistry at Erfurt, who examinol 
The liquor remaining amounted to about two ounces. 

surface was covered by a trausparent crust, so I 
ng that the vessel might be inverted without spil* 

any of the liquid. At the bottom of the vesKl were 1 
unber of crystals, which proved on cxairination ta%. 
wlpbate of potash and carbonate of potash f. The.^ 
It on the top consisted partly of carbonate of potash, 
tly of crystallized silica. These last crystals had as- \ 
led the form of tetrahedral pyramids in gioupes>jj 
f were perfectly transparent, and so hard that thcy^ 
idc 6ie with steel {. 
^. Silica oeiiher combines with oxygen, with thj Acda^sl 



■Bofnui), ii. 31. 

t pKufa (ombincd uriih nilFhiiiic icid aii4 carbooic acid . 

i NidiAlwii'i Jtn*al, i. 117. 

c< 



]0» 



EARTHS PROFEX. 



Book H. 



Action ef 



Cfbarjtct. 



Simple combustibles, nor with metals ; but It coBlniicr 
with many of the metallic oxides by fusion, and fonas . 
various coloured glasses and enamels. 

5. Azote has no action on silica ; neither has muria* 
tic acid when the silica is in a solid state ; but when 
the silica is combined with an excess of alkali, murii* 
tic acid dissolves the compound, and forms a penna* 
nent solution. By concentrating this solution^ the si- 
lica separates from it in the form of a jelly. 

0. There is a strong affinity between silica and fixed 
alkalies. It may be combined with them either bj fu- 
sing them along with it in a crucible, or -by boiling the 
liquid alkalies over it. When the potash ezceeda the 
silica considerably, the compound is soluble in water^ 
and constitutes what was formerly called iiguor siHcwm 
and now sometimes silicated potash or soda. When the 
silica exceeds, the compound is transparent and colour- 
less like rock crystal, and is neither acted on by waler^ 
itir, nor (excepting one) by acids. This is the 8ub« 
stance so well known under the name of glasx* 

Silica is not acted on by ammonia, whether in tb^ ga. 
seous or liquid state. 

7r There is a strong affinity between barytes and ti» 
lica. When barytes water is poured into a solution of 
silica in potash, a precipitate appears, which is consider- 
ed bv Morveau as the two earths in a state of combini- 
tlon *. Barytes and silica may be combi^ied by means 
c»f heat. The compound is of a greenish colour, aod 
«oheies but imperfectly f. The effect of heat 00 va- 



* Mnvclu, Aim, Je Cbim. lix*. ajO. 
\ V;iu^i('!in, ihid. xxix. i;t. 



lixtures of barytes and silica will appear from 
owing experioients of Mr Kirwan *. 



ica 
rytes 



Heat. 



150^ Wedg. 



ica 
rjtcs I 



icm 
lytet 

ica 
rytes 



ica 
rytes 



ica 
r3rtc* 



ica 
cytes. 



150 



150 



14S 



148 



150 



150 



FSfiLU 



A white brittle mass. 



Abrittlehard mass, semi- 
transparent at the edges. 



•«iPM*< 



Melted into a hard, some- 
what porous porcelain 
mass. 



A hard mass not meltedP. 



iThe ed?es were melted 
mto a pale gcie<fnish {nat- 
ter ^tween a poreeiaio' 

and euameJ* 



Melted' into a somewhat 
porous porcelain mass. 



Melted into a yellowish 
and partly greenish whitt 
pi>rous porcelain. 




itiao and silica combioe wkh each other nearly •sirontijo, 

ame iiianiier. 

« is alM an affinity between silica and liTtne. ximc, 

lime-water is poured into a aolation of silica in 

a precipitate appears, as Stucke discovered. This 

ate is a compound of silica and lime f. These 



ran's Miner, u / 7, 

lUo, ^un. de Ciim, xxii. XiO.— Monrtui, ibk* ixii. ftJO. 



i^J 



EA&iui rAoru. 




Mifona* 



And 



two cuths maj be combined also bj means of beat. 
Thej form a glass, provided tbe quantity of lime be not 
inferior to that of silica. Tbe effect of beat opoo thae 
earths, mixed in Tarioos proponiooi^ will appear from 
the following experiments of Mr Crwan *. 




KcaL 



50 

50 Silica 



150"Wedg. 



80 Lime 
SO Silica 



20 Lime 
80 Silica 



156 



156 



Melted intoa mass of a white 
colour, semitransparcnt at 
the edges, and striking fire^ 
though fecblj, with sled 
it was somewbas h c mecii 
porcelain and enamel. 



A yellowish white loose 
powder. 



Not melted, formed a brit- 
tle mass. 



Equal parts of magnesia and silica melt with grcst 
difficulty into a white enamel when exposed to tbeflMit 
violent heat which can be produced t* Tb^ arc infa- 
siblc in inferior beau in whatever pr o p o rti on diey sre^ 
mixed %. 

There is a strong affinity between alumina nod sili* 
ca. When equal portions of silicated and altmsinaled 
potash are mixed together, a brown zone iwmwKatdy 
appears, which may be made, by- agitatioa, to piM 
throtigh' the whole liquid. After standing about an 
hour, the mixture assumes the consistence of jelly ||. 



• Kirwan't MU. I 56. f Lavoiikr, Mmi, P^r. 178;, PU598. 

I Adiard, \Um, Betl. 1780, p. 33. 
(| BAonreao, Ahm, dtC'jim, xku 149' 



Ded into a paste with water, and dried, they Chap. iV^ 

1 contract a considerable degree of hardness. 

:ed in the temperature of 160^ Wedgcwood, 

me very hard, but do not fuse *. Achard 

a infusible in all proportions in a heat pro« 

e inferior to 150^ Wedge wood. But when 

a very strong heat, they are converted in* 
»f opaque glass, or rather enamel. Porcelain, 

brick, tiles, and other similar substances, are 
chiefly of this compound. Mixtures of sili» 
nina in various proportions constitute clay^ ; 
re seldom uncontaminated with some other 

'■ - < 

w% from the expejriments of Achard, that 
I of lime, magnesia, and silica, may be melt* 
reenish coloured glass, hard enough to strike, 
teel ; that when the magnesia exceeds either 
r two, the mixture will not jnelt ; that when 
xceeds, the mixture seldom melts, only in« 
iiim in the following proportions; three silir 
ae, one magnesia, which formed a porcelain ; 
rhen the lime exceeds, the mixture is gene- 

let. 

re of silica and alumina msLj also be combined 
es or strontian by means of heat. The mix- 
readily into a greenish coloured porcelain %• 
le experiments of Achard and Kirwan, we 
in mixtures of lime, silica, and alumina, 
iqae exceeds, the mixture is generally fusible 



. *78o, p. 33. and Jcu^. Je JPlyi. xii^ | Kirwar. 



104 KAKTRft PROPER. 

Book II. either into t glass or a porcelain, according to the proi* 
* V portions* The only infusible proportions were^ 

2 3 ; Lime 

1 1 Silica 

2 2 I Alumina. 

That if the silica exceeds, the mixture is freqaentlj fit- 
sible into an enamel or porcelain, and perhaps a glass ; 
and that when the alumina exceeds, a porcelain nsj 
often be attained, but not a glass *• 

As to mixtures of magnesia, silica, and Rlontni, 
ivhen the magnesia exceeds, no fusion takes ;|ilace it 
150^. When the silica exceeds, a porcelain mayoftes 
be attained ; and three parts silica, two magnesia, sod 
one alumina form a glass. When the alumina exceed^ 
nothing more than a porcelain can be produced f • 

Achard found that equal parts of lime, magnesia, lili* 
ea, and alumina, melted into a glass. TKejr' fused si* 
so in various other proportions, especially whieU the b« 
lica predominated. 

Silica differs from all the other eanhs in not eombi- 

I ■ 

ning with any of the acids rxcept the fluoric, phospho- 
ric, and boracic i to which perhaps we may add the 
muiiatic. 

Silica is one of the most important of the earths. It 
is the chief ingredient of ^hose stones whi^h seem to 
constitute the basis of this terrestrial globe. It is an 
essential ingredient in mortar, in all kinds of stonewsn^ 
and in glass. 
Compoii- ^^ Oavy made many experiments to ascertain the 

^^' compositiun of silica, and has rendered it pVobable that 

it is a metallic peroxide. As it approaches in some of 



• Kinrsn't ATm. i. 73. f IW. 1 7a, 



MUmAm 150 

Its propertiet to rarieus insoluble salts, he thought tt re- Chiy > !▼• 
quisite, in the first place, to inquire whether it might 
not be a conipoiuuLotaB nnknowii actdand earth* But 
when exposed to the action of a powerful galvanic bat* 
tery it was not decomposed ; of course there was no rea* 
son for considering it as propable that it was of a saline 
nature. On the supposition that it was a metallic per« 
oxide. It waa f xposed to experiments preciaaljr similar 
Co those formerly described, when treating of the de« 
composition of alumina, TUd the results wete exactly 
the same. Hence there isreason to consider it as a com- 
pound of oxygen an4. a pecnlUlL.ni^tals though the ex* 
periments cannot be conndered quite decisive. To the 
supposed metal Mr Davy proposes to give the name of 



' ; 



« 









'■ l.^'l J- . 


m 


■ '■.••[ •.' > ;■ 




• 


■ 


■•'■■) '• 



I . 



« • 






3M ftB«MS8 Wr 

Jookll. 

DiWMMlI* 



CHAP. V, 

• I 



• 1 I. 



inSBhAttKS on THE ALKALIES AND 



- 1 



f 

■ ■ • 




KM 


M't 


iiiai. 


■ • 




' 






• . : ?■■ 


^ , 


■ 


: . 


• ■ 


i 






» 


- 


•.--.•• 1 ' 




■ 







Th. te™. ^iaU «d earti wcr. brought inl. .«. 
long before chemistry became an accurate tcie|ice. We 
need not therefore be surprized that their meaning wu 
somewhat vague ; and that as chemical substances muU 
tipliedf it became difficult to ascertain to which of the 
two thej ought to be assigned. Two properties appear 
to have been considered as essential to the alkalies. 
Originil 1* They were capable of combining with acids, and of 
^St^Sf^S!^ depriving them of their acidity, while they themselves 
€arth. lost their characteristic properties, or were neutroKvud* 

2. They were soluble in water. Insolubility in water, 
or aridity, as the chemists termed it, joined tQ incom* 
bustibility, was considered as characteristic of an forfb* 
These properties served to arrange newly discovered 
substances. If they combined with acids, and were so« 
luble in water, they were considered as alkalies ; bnt 
if they were insoluble in water, they took their station 
among the earths. Hence soda, as soon as discovered, 
was denominated an alkali, while lime, barytes, atron- 



AXKAUSS AMD EAItTHS. 

i lun, Slc. wete successively placed smong ihc c&rthi ; ^*P- ^' . 
Cor the solubility of the firjt of these bodies in water ~ 

J was long misunderMooti. Tlte whole of tbe lime wu 
not considered as soluble in wiier, but t ceTiatn portion 
of it which Bppioachcd alkalies in its naiuie ; 2nd though 
this error had been reciiiied before ihe discovery of 
itiODtisD, yet analogy led chemists to class this body 
along with lime <u)d baryics, which had alrcadj taken .,_« 

their place among earths. 
The alkalies naturally subdivided themselves inM> f-"^f^ 
JUtJ and volatUe t a distiuclion mude at an early pc- thcnt. 
rifldt tufficiently correct, and attended with many ad*^ 
vantages. The subdivision of Ihc earths into alkaline 
and proper was a tnucb later itnpToveoieni. Indeed it 
was only sftei the eanhs had been examined in a state 
of tolerable purity that such a subdiviuon was possible. 
Those earths that possessed all the characteristics of 
ilkalics, excepting that of being very soluble in water, 
verc denominated aiialuie, wliilc those (bat were inca- 
pable of neutralizing acidii, and which were iiisoluhle 
JQ water, wcri: considered ai more peculiarly entitled lo 
tbe oaiDG of earib. This subdivision was obviouslj 
intoided to correct the too great vagueness of the terms - 
Worth and aliali as originally apphed. It appears more 
l^roper than some other methods that have been prac* 
tised for the same purpose. Fourcroy, for ioslancc, 
:lmsses barytes and strontian with the alkalies. No 
l^ault can be found with this arrangement, because the 
vlivision of these bodies into earths and alkalies is per- 
fectly arbitrary. But surely if barytes and strontian be 
placed among alkalies, lime ought not to be excluded ; 
for barytes and strontian do not possess a single alka- 
line property of which lime is destitute. Andiflimc 



« 




lOi MMAIIK8 Oir 

be Reckoned tmoog the alkalies, no good reason can be 

given vrhy magnesia should be excluded* The truth 

is, that these bodies graduate into each other so nicely 

that thejr can scarcely be placed in diCfierent classes* 

This is a sufficient reason for preferring the comdion 

division to the new one proposed by Foutcroy« 

BmfioUcc's - Bcrthollet has suggested another definition pf alkalies, 

dcfiokiooof 

^Usii. which appears to nw tnuch more coprect than that of 

Fourcroy. According to him, all bodies capable of 

^ mmtroHving acids are ontltled foihia iiaai^ nXfUkalUs. 

AHaUwky is the property of neoiraliving acids^ and 

itciduf that df neatratitlng: Mmlku Aocording to this 

definitioo, the alfcaKes, both fixed and volatile,* and tfn 

afltaline earths, ought to -be'coniMeted as aUa&t. 

Though' objections might perhaps be fetarled to this da«' 

fiaitiont J|sia the case indeed with all definitions what* 

i^mePf^^Uk most be -allowed to be mteh oMre pr^eisei 

apdghrea xi%% mow «a|ia6Mrt4ry notion :«f«lkidiiii<y 

than any^ihflit* preceded 4t.' - But if the- capacity of nei|« 

traliafaig^acids ceiistimtta alkalinity, it is obrf ous that 

those boiies inn^t pofscH mart of -that prepay, which 

aiji'aaM capable of* neotirali ting acids, or whi^h are ca^ 

pabl»6f neutralialagihe |freatest qaahtity df iidd. Ac^ 

cosdiog to tliis doctffne'^he alkalies arrange -themsclWs 

in th^ following iot^l- ; that oAe"Standing' first which 

iiootvalizasthe.g^esmst^uantitylbf Idd*; " 

''■^- ^Ammbnia,- '' " -' ' '' 

^ m • m 

'•' ■• • '"Mdgirtsia, 

.-,:«.:£ ■. • '-'drte; ■= :!■'-'■ : ••■ 

• • • 

. ' •!■:■.'. ' I ■> I'l I I II ■■ ! ■ , ■ 



r .1 ^ 



• Bmholht,' ^Mtimie Chemidm^ i," p. laj. Tbc ordcr was estibllibcd 
6om'ti^ bpetkienu of KirWin* 



AUCAUtt AUD SARTHS. IQA 

Soda, " Chip.V. 



Potash, t 

Strontian, 

Barjtes. 
earths proper combine with ecids^ bot do ncit 
tndize them *• 

rhe alkalies (using the word in BerthoUet's sense) 
not combine tvith oxjgen. ; They do not eel «pon 
Irogen nor carbon ; but thejjr combine with snlpbor, 
unite with phosphorus, or at least act upon it with 
siderable energy. Their action upon metals is not 
f remarkable. Some metallic oxides thej distcdve^ 
ile upon others they have no efiect. They are all 
re or less scduble in water except magnesia $ but the 
aline earths much less so than the othera« 
The earthe proper do not unite with oxygen, at least 
iar as has been ascertained in a aatisfiutory manner. 
tj do not unite with simple combustibles nor metals, 
have a much less tendency to enter into combina*- 
is than the alkalies. 

fhe following Table exhibits some of the most 
larkable characters of the alkaline and proper 
thsf. 



V 



To this there tre tome exceptions. This eonsHnuctoneof the do* 
of Berthollet'k de6mtioii. 

In this Tabic several properties have been pbccd* with which tbr 
er will become acquainted by perusing the mbsefnci^ part 'of thii 
k. It was thought worth while to add them, that the Table might 
ain the most important proper ties of the eirths collected tctgethcr. 



Book It 



t(tiA«n ot 



J 


•s 
.5 

If 


1 

H 

1 


1 


= 

11 


e' 

1 

St 


i 
1 

T 

3 
4 

5 



-S 

1 


3 

1 

2 


1 

— 

1 


1 

1 
3 

4 


Baryies 


0050 


Stronl. 


0-005 


2 
3 


"■ 


Umc 


0-002 


Mngnei. 


0*000 


4 






A.lum. 


0-000 




' 


~ 


1 


Yttria 


0-ono 






Cluciiw 


0-000 




' 


2 
3 


2 


1 
8 


2 


Zircon. 


0-000 




S 


3 2 


Silica 


O'OOO 









■It dosenrei ctteadon, that s considerable imnber of 
theie bodiei na^ be divided into pairs, which bare « 
Urikiog rcsemblaoce to exeh other. These pairs are^ 
CPuash S Yttria 

. *• tSodft ^* iGlQCiM 

C Barytei C Alumina 

^StrenMn '*' (Zirconia 

Bnt tbe r cK MiMtace between tlomina ind ^drconis, 
Irbieb comtituie the last pair, h not so close as that 



^ After being ptcnpitlted. 




betw e en tb^ bodies which form the other pairs. Anr- ^ Gtep^ V* 
monia^ magnesia, and ailica, have none of them corres- 
ponding inbstances. 

Now that the secret of the composition of the alkalies 
tnd earths has been iwealad, it is obvious that they all 
bekmg to the same class of substances, and that they 
oogbt to be placed among the metallic oxides* That 
the conjecture 6f the old chemists has been verified with 
respect to th^^carthsi while the coastitntion- of the al« 
kalies has turned out different from everj previous con- 
lecture. 



■ - • • • * jj 







!^9e 



» 



• 4 



DIVISION U.; 



or 



j^ 



1 ■ ■ I 



PRIMARY COMPOtlSTDS. 



IP the science of chemistry had made sufficient progres s , 
this division would comprehend all the compounds whi 
the simple confinable bodies are capable of forming wit 
each other. But we are not jet sufficiently acquain 
with all of these combinations to be able to detail 
at length } and many substances luiown to exists and 
belong to this division, have not been sufficiently ex 
mined to enable us to assign them their proper aitua 
ation. We cannot, therefore, introduce all 
compounds into this division, but those only, in t 
analysis of which chemistry has made considerable prf^^* 
'gress. « 

The confinable bodies were divided into four classes ; 
namely, Oxtgek, Combustibles, Ikcombustiblxs, 
and Metals. Oxygen unites with all the bodies be- 
longing to the other three classes ; and with most of 
them it unites in various proportions. United in one 
proportion, it forms a set of bodies incapable of neutra- 
liiing alkalies, to which the name of oxide has been as« 
lagned 9 united in another proportion, ir forms a set of 



miMAKT OOMFODXBS. 

I bodies called adds, capable of neutraiking alkalies- 

I £ach of ihcsc sets comprehends under it a variety of ' 

bodies of great importance in chemislrj, and which, 

lUcreforr, deserve to be examined with attention. The 

combustibles unite with each other, and form a very 

numerous class of bodies still capable of combustion. 

Kid which, therefore, mny be called compound comhus- 

They unite also with xncotfihuitibUs and with 

. The intombusttbles, as far as we know, do not 

• with fact other, not with the mttali ; but the me- 

' I>b combine logether, and form compounds called a/- 

1^1. Hence wc sec that the primary compounds natu- 

nlJjr divide themselves into the six following classes : 

]. Oxides; I 

S. Acids i 

3. Compound combustibles; 

4. Cbmblhations of combustibles arid incombustibles; 

5. Combinations of combustibles and metals \ 
fi. Combinations of metals with each other. 

Of these classes, the two last, in the present state of the 
Science, are of least importance. The compounds be- 
""g'^f ■*> liiem are scarcely entitled to a separate exa- 
niitiation, and for that reason were iniroduced in the 
first Book of this Work, during ilic tsaminalion of ibe 
*im[ile substances, of which they are compounds. As 
*o the fourth class, we are at present acquainted only 
^iih otic substance which we know to belong to it. 
That substance is drnmonta, which was arranged witli 
ibc fixed alifalies and earths, for reasons formerly speci- 
fied. The first three classes of primary compounds 
uione remain to be examined. They shall form lh« 
mbjeci of die following chapters. 
To/. //. « 



If4 KiMA&r cotfPomiofi 

Book IT. 
Di^riaioo II, 



GHAP. I. 



OF OXIDE S» 



gov 



Combint- "^^ ^^^^ *^" alrcidy that oxygen cbrobines mih 
tion of 017* bodies in various proportions, constituting a variety of 

compounds with almost every substance with which it 
is capable*of uniting. Now the whole of the compoundi 
into which oxygen enters may be divided into two sets: 
!• Those which possess the properties of acids i and, 
2. Those which are destitute of these properties. The 
first set of compounds are distinguished by the term ^ 
cids ; to the second, the term oxide has been Appropri* 
ated. By oxide, then, is meant • substance composed of 
oxygen and some other body, and destitute of the pro* 
perties which belong to acids. It is by no means un- 
common to find a compound of the same base and oxy- 
gen belonging to both of these sets, according to the pro- 
portion of oxygen which enters into the compound* la 
all these cases, the smaller proportion of oxygen coor 
stitutes the oxidi ; the larger the acid» Hence it fol-^ 



oluMs« llB 

that oxides alwajs contain less oxygen than adds 0"^^, 
the same base. 

e oxidesy then^ which we have to examine in this 
er, are combinations df oxygen with the simplo 
nstibles, the simple incombastibles, and the me- 
substances which maj be denominated the bases 
t oxide. Now the oxides differ considerably firoQi 
other, according to the nature of the base and the 
e£ in which the combinatfon has been formed* 
i of them are frpJucU of combttstion, others of 
are comimtible^ while a third set are supporters of 
rustion. The metallic oxides, which have been al- 
r examined^ belong partly to the first and partly to 
sist of these classes. The following Table exhibits a 
of the different oxides (omitting the metallic) ar- 
id under their respective classes. 

I. Oxide Products. 

Bate. Name. 

Hydrogen Water. 

II. Combustible Oxides. 

Carbon , Carbonic oxide. 

Phosphorus Oxides of phos^oms. 

Sulphur Oxides of sulphur. 

III. Oxide 



Azote C Nitrous oxide. 

C Nitric oxide. 
Muriatic acid • • • • ..Oxymuriatic add. 

examination of these oxides shall oeciqiy our atten* 
m Ihe fbUowiBg Sectioas. 

Hd 



11^ OXIDES. 



B'ok If. 

Division If. 



I. OXIDE products: 

Hydrogen differs from the other simple combustibles 
in several respects. It is the onlj one ot them which is 
capable of uniting with onl j a single dose of oxjgeo, 
and of forming a compound entirely destitute of acid pro* 
perties. This compound is Water, It is foriliec bj 
combustion, and is therefore vl product. All the other 
products into which the simple combustibles enter are 
acids. The only oxide product, then, at present knowa 
(exclusive of the metallic) is water. 



SECT. I, 



OF WATER* 



1 HIS well-known liquid is found in abundance in 
every part of the world, and is absolutely necessary for 
the existence of animals and vegetables. When pure, 
in which state it can be obtained only by distillation, it 
is transparent, and destitute of colour, taste, and smell. 
t^Vght. 1. As this liquid, from the ease with which it may 

be procured in a state of purity, has. been chosen for a 
standard by which the comparative weight of all other 
bodies may be estimated, it becomes of the greatest im« 
portance to ascertain its weight with precision : But it^ 
density varies with the temperature. At the tempera- 
ture of 30^, its density is a maximum ; ahd for the 
two or three degrees on each side of 3Q^p the vma« 



WATU. 117 

tton of Us density is scarcely perceptible. Now, from . ^^P'^'. 
the experiments of Lefevre Gineau, performed with 
great care, in order to ascertain the weight of the mille- 
gramme, it follows, that, at the temperature of 40^, a 
French cubic foot of distiUed water weighs 10 lbs. and 
223 grains French = 529452*9492 grains troy*. There- 
fore an English cubic loot, at the same temperature, 
weighs 4S7102'4940 grains troy, or 990*0914101 oun- 
ces avoirdupois* Hence a cubic inch of water at 40^ 
weighs 252*953 grains, and at 60% 232*72 grains. A 
cubic foot of water, at the temperature of 55°, weighs, 
according to the experiments of Professor Robison of 
Edinburgh, 098*74 avoirdupois ounces, of 4i7*5 grains 
troy each, or only 1*20 ounces less than 1000 avoirdu- 
pois ounces : so that rain water, at the same tempera- 
ture, will weigh pretty nearly 1000 ounces. The spe- 
cific gravity of water is always supposed -= 1*000, and it 
ii made the measure of the specific gravity of every other 
body. 

2, When water is cooled down to 32®, it assumes lea ; 
the form of ice. If this process goes on very slowly, 

the ice assuores the form of crystalline needles, crossing 
each other at angles either of 60^ or 120^, as Mr de 
Mairan has remarked ; and it has been often observed 
in large crystals of determinate figures f. Ice, while 
kept at a temperature considerably below 32^, is very 
hard, and may be pounded into the finest dust It is 
elastic. Its specific gravity is less than that of water. 

3. When water is heated to the temperature of 212®, ^*«"* 



• Jpur, de Pbys, xlix. l^U 

t See obsenratiODs on this subject bj Grew. Pbll. Trans. Abr. u. 54. 



Book n. it boils, and is irraduallr converted into steam. Ste4|ai 
< » ^ ■■■> is an invisible fluid like air, bat of a less specific gravity. 
It occupies about 1800 times the space that water does. 
Its elasticity is so grcat^ that it produces the most vio* 
lent explosions when confined. It is upon this principle 
that the steam-engine has been constructed. 

The phenomena of boiling are owing entirely to the 
rapid formation of steam at the bottom of the vessel. 
The boiling point of water varies according to the pres- 
sure of the atmosphere. In a vacuum water boils at 
70^ ; and when water is confined in Papin*s digester^it 
Boiling may be almost heated red hot without boiling. The 
Kncdhj mixture of various sahs with water afiect its boiling 
Mitt. point considerably. Mr Achard made a number of ex. 

periments on that subject ; the result of which may h« 
seen in the following Tables *. 

Class L Salts which do net affect the Boiling 

Sulphate of copper. 

Class II. Salts which raise the Boiling Point 

o f Muriate of soda 
^ ^ I Sulphate of soda 



^ a [ Sulphate of potash 

D *r { Nitrate of potsish 

^ .2 I Boracic acid ] ^ -'s 

^ (^Carbonate of soda J •^ 



9 
< 

This augmentation varies with the quanti^ of snlt 




* Tramt, Beri'm, 1785* 



. WATIK. m 

Ired. In general^ it is the greirter the nearer the , Cfcir»^ 
ioo approaches to satnration. 



<» 




!ukss III. Salu vfbkb hwn Ai Bcilmg PmHi. 

m 

r In a small quantity, lowers the boil* 

J^ < log point • •« • 1*350* 

Q^ Saturated solution of • • ••• 0*22 

*, c C In a small quantity 2*47 

*""°^'°»«"**»^is.tu«ted wluti« of... l-l 

r A verj small quantity of •••• 0*0 

my < A greater quantity ••••• 0*7 

(^A saturated solution of •••«...««.«*»».oo^ 0*0 

>hase of lime, * ^ ^ 0*02 

»hate of xinc, r . ---,«-^:«« 3 0*45 

ihate of irop, ^ « "7 proportion, < ^.^^ 

tateof lead, J C 1*24 

Class IV, 

• ^ r Small quantity of, lowers the 

late ot A jj^yj^g p^j^^ ^.^^e 

imonia, ^ Saturated solution of, raises do. 9* 79 

bonate of C Small quantity o^ lowers do. 0*45 
otash, \ Saturated solution of, raisesdo. 11*2 

Vater was once supposed to be incompressible ; but 
oootrary has been demonstrated by Mr Canton, 
s Abb^ Monger made a number of experiments, 
( after that philosopher, on the same subject, and 
dned similar results* 

• Water is not altered by being made to pass through Action tf 
d hot tube. Heat does not seem capable of decom- ^*^ 
ing it \ neither is it affected by the action of light. 

• It has the property of absorbing atmospheric air; Abiorbt 
it always contains a portion of it when it has been ^^ 



^20 OKIBEl* 

Book IT. tSLpoted to the atmosphere. Tbe gretter part of this 
' ^'^*^ . air is driven off by boiling : but, from the experiments 
of Dr Priestlejy it appears that tbe whole of it is not 
separated ; nor can it be completely separated witboat 
great difScultj. Water owes its agreeable taste to the 
presence of air ) hence the insipidity of boiled water, 
it absorbs oxygen gas in preference to air, an4 nearly 
in tbe same proportion, as was first ascertained by 
Schcele. 
How lir A|r Driessen has shown, that in order to free water 

^^^ ^ from air, it must be boiled at least for two hours, and 
ffqm it. ]^cp( in n g^sk with its mouth inverted over mercury. 
If it be exposed to the air, after fhi^ process, for ever 
so short a time, i( imiiie(liately absorbs some air \ ^ 
prQpf of tbe strong aifiaity which it has for that fluid ^ 
This philosopher has pointed out the following method 
pf ascertaining whether water be perfectly free from 
air. Tinge the water blue with litmus, fill a flask with 
it, invert the fiask under water, and iptroduce into it 
pure nitrous gas till about ^^ of the vessel is filled. If 
the water contain air, a portion of the nitrous gas wi^ 
combine with its o^^ygen, and be converted into nitric 
acid. The consequence of which will be, that the lit- 
fnus will assume a red colour^ Even the proportion 
pf air in the water may be estimated by the quantity of 
ammonia necessary to restore the blue colour to the lit* 
inus,. If the litmus retains its blue colour, we may be 
pertain that the water which we try contains no sen- 
sible portion of air f. It is proper to remark, how. 
f:yer, that this experiment does not succeed in a satis- 



f Phi!. Al#/. |8 3, XV. %: s. f Ibid, 



Dtnner, unless an unusual quantity of oxygen , Chap, u ^ 

present. No effect is produced when nitrous 

itated with good spring water. 

atcr has no action on the simple combustibles ^<^?" «f 

^ * the simple 

Id, nor does it combine with any of them, combusti- 
on does not act upon it even at a red heat ; but 

at that temperature decomposes it> forming 

acid, and various species of heavy infiamma* 

The action of phosphorus at a red heat has 

! tried. Sulphur, as far as is known at present, 

decompose it. 

; the metals, iron, zinc, antimony, and tin, de- of the me* 

! it when assisted by heat ; silver, gold, cop- ' 

platinum, have no effect upon it. The action 

her metals at a red heat has not been tried*. 

ater dissolves the alkalies and alkaline earths. Alkallet 

ths proper are insoluble in it. It dissolves also 

1 salts, and is capable of combining with a great 

>f bodies. 

ater has the property of uniting with bodies in Water coir- 

c • J- 1 u J binciintwt 

:rent ways, oome it dissolves ; the compound forme. 

liquid, like water. In this way it unites with 
salt, with sugar, and a vast number of other 
Other substances combine with it without lo- 
ir solidity. The water in this case loses its li- 
m, and assumes that of the substance to which 
lited. In this way it unites to lime, to alumi- 
lany saline bodies, and to a variety of metallic 
When the compound of water with another 
e remains liquid, the proportion of water is un- 



J/cw. Pun 178/. f. 2;f. 



122 

Book If. 



Hydrates. 



AIV aline 
and earthy 
hvdrateSi 



limited ; but when the combioation formed is folid^ the 
water combines always in a certain determinate pro- 
portion. 

To the first of these combinations, or the iobtikns of 
bodies in water as thej have been termed, considerable 
attention has always been paid ; bot the second kind, in 
which the water assumes a solid form, was very nrach 
overlooked, if not altogether neglected, till the atten- 
tion of chemists was drawn to them by Mr Proost, who 
has given to such combinations the name of bydraiii. 
Thus the combination of lime and water, usually called 
slacked lime ^ is in his language zbydnUe of lime: in 
like manner, the crystals of barytes and strontian are 
hydrates of these alkaline earths* and crystallized potash 
and soda are hydrates of the fixed alkalies* Though the 
term hydrate is in some respects exceptionable, we shall 
continue to use it, as no other has been suggested* The 
compounds called hydrates deserve attention, since tbcy 
differ very considerably in their properties from those 
bodies with which they have been hitherto confounded. 
Thus the hydrates of lime, barytes, potash, &c. are 
very different in several respects from lime, barytes^ 
potash, Sec. 

The hydrates of potash and soda are crystallized^ and 
contain always a determinate proportion of water : ac- 
cording to Proust, about 30 per cent. When dissolved 
in water they occasion cold ; whereas the alkalies imm 
the state of powder produce heat. The same obserya.«- 
tions are applicable to the hydrates of barytes and stroo «- 
tian* The proportion of water which combines witl^ 
lime is much less considerable than that which enters 
into the composition of the hydrates just mentioned* 
Hence the hydrate of lime does not crystallize, but re** 



WATKR« 12S 

auins usually in the state of a powder. We kno w, how- Chap. r. 
ever, that it retains the water with great obstinacy, and "^ 
that the formation of it is one of the principle causes of 
the solidification of mortar *• The hydrate of alumina 
is no less remarkable for the obstinacy with which it 
retains its water. It is the substance to which Saussure 
gave the name of spongy alumina. 

But the hydrates ot the metallic oxides are |he most Mctallioe. 
remarkable. They first drew the attention of Proust, 
and induced him to invent the term hydrate. His ob« 
servations, as far as regards the hydrate of copper^ have 
been called in question by BetthoUet junior f , but his 
arguments do not appear to me sufficiently conclusive 
to overturn the ingenious theory of the Spanish che- 
mist. He has demonstrated indeed, that the hydrate of 
copper usually retains a small portion of acid ; but be 
has not shown that its peculiar properties are owing to 
that acid, while Proust has made the contrary more 
than probable, by ascertaining that the properties of 
th^ hydrate remain the same, even when the proportion 
of acid varies, and when it is so far diminished as to 
T>e no longer perceptible. 

When copper is dissolved in nitric acid, and a suffi- Hydrate of 
cient quantity of potash added to the solution, a blue ^^' 
powder falls to the bottom, which when sufficiently 
washed, and carefully dried, coheres together, and forms 
a brittle mass breaking with a vitreous fracture. This 
mass is the hydrate of copper. It has an exquisitely 
disagreeable taste, and acts with great energy upon the 



* Stc Prousr, /wrr. de Pbyt, lix. 347, 
f Siait^ue Cbewufue% ii. 455. 



124 OXlD<S« 

Book ir. system when swallowed, or even kept in the mouth. 

' ^'* When distilled it yields 25 parts of water, and leaves 

75 of black oxide of copper. 

of iroo. When the solution of iron in sulphuric actd is treat- 

ed in the same way, a green powder falls, which is a 
hydrate of iron. These two hydrates are delicate, and 
easily lose their water. But some of the other hydrates 
of the metallic oxides retain their water with great ob« 
atinaoy . This is the case particularly with the hydrates 
of nickel and cobalt, which resist the action of a const^ 
derable heat *. 

Of tin. When tin dissolved in muriatic acid is precipitated 

by potash, a white powder is obtained, which washed 
and dried in the heat of boiling water is a hydrate of 
tin. When distilled in a retort it loses 5 per cent, of 
water, %nd is converted into protoxide of tin f • 

Most of the metallic hydrates are remarkable for the 
brilliancy of their colours. They are much more easily 
dissolved by acids than the oxides ; and when put into 
the mouth they affect the organs of taste even more 
powerfully than the metallic salts. 

GkKtcon- 10. Ail gases in their usual state contain combined 
with them a quantity of water, which often amounts to 
a considerable proportion of their weight. Part of this 
water may be abstracted by exposing the gases to sub* 
stances which have a strong affinity for water, as dry 
potash ; but part adheres with a great deal of obstinacy, 
and perhaps cannot be removed by any method in our 
power. 

11. Water was believed by the ancients to be one of 



taw water. 



♦ Proust, /wrr. <f€ Bbyt. L'x. 347. f Ibit'. f- 33?- 



Watzx. 1S5 

the four elements of which every other body iscompo- ^^p, i. 
udi mild, according lo Hippocrates, il was the subslaace 
which nourishes and supporis plants and animals. That Pi»™"m»- 
u-aiet nasan uncUuigcabte element contmued to be be* tun of w** 
licvcd till the time of Van Helmont, who made plants ^"' 
grow for a long time in pure water: from which ex- 
periment it was concluded, that waicr was convertible 
iato all the substances found in vegetables. Mr Boyle 
having digested pure water in a glass vessel hermeti- 
cally scaled for above a year, obtained a quantity o£ 
earthy scales ; and concluded, in consequence, that 
he bad converted it partly into earth *. He obtain- 
ed the aamc earth by distilling water in a tall glass 
vessel over a slow firef . Margraff repeated the expe- 
limcni with the same result, and accordingly drew ibt 
lame conclusian. But the opinion of these philoso- 
pbcis was never very generally received J. The last 
person who embraced it was probably Mr Wasellon, 
who published his experiments on the subject in the 
iMimai tit Plryii'jue lor nSO. Mr Lavoisier had 
proved, as early as m3, that the glass vessels in which 
the distillation was performed lost a weight exactly 
tqual lo the earth obtained. Hence it follows irresist- 
ibly that the appearance of the eaiih, which was silica, 
proceeded from the decomposition of ihe vessels ; for 
glass contains a large proporliun of silica. It has been 
tiace shown by Dr Priestley, that water always decom. 



• Shaw'i B<yt^. lil. 41?. t Ibid. i. s/.?. 

tvvtn i((oi.ui ci[ ill iheficti rclMiDE to thiinibjK' 
CJ«i«/e«7(.it-Ji7- 



IQ6 



OXIDtS. 




Book IT. poses glass when applied to its surface for a long time 

Diriiioo IT* • • • « 

m a high temperature. 

Water is now known to be an osnde of hydrogen, or 
ar compound of oxygen and hydrogen* As this disco* 
very has almost entirely altered the appearance of the 
science of chemistry, by famishing an explanation of a 
vast number of phenomena which were formerly ines- 
plicable, it will be worth while to ^vc a particular ae» 
count of the different stepa which gradually led to ic 

The first person probably who attempted to disco- 
ver what was produced by burning hydrogen gas ms 
Scheele. He concluded, that during the coatbostioi 
oxygen and hydrogen combined, and that the product 
was caloric. 

In 1770 Macquer, assisted by Sigaud de la Food^ 
set fire to a bottle full of hydrogen gas, and placed t 
saucer above the flame, in order to see whether any fii. 
liginous smoke would be produced. The saucer it- 
mained perfectly clean ; but it was moistened with 
drops of a clear liquid, which they found to be pare 
water •• 

Next year Bucquet and Lavoisier exploded oxjrgco 
and hydrogen gas, and made an attempt to disco?er 
what was the product ; about the nature of which tbey 
had formed different conjectures, fiucquet had suppo- 
sed that it would be carbonic acid gfis ; Lavoisier, on 
the contrary, suspected that it would be sulphuric or 
sulphurous acid. What the product was they did act 
discover ; but they proved that no carbonic acid gu was 



• Macquer*! Dictionsry, irr. Cat it^lsmmMf. 



WAT£R« 127 

ed, and consequently that Mr Bucqaet's hypothe- ^ Chap. r. 

rasiU founded f* 

i the beginning of the year 1181, Mr Warltirey at 

Yquest of Dr Priestley, fired a mixture of these two 

s contained in a copper vessel ; and observed, that 

the experiment the weight of the whole was di- 
shed. Dr Priestley had previously, in the presence 
[r Warltire, performed the same experiment in a 
( vessel. This vessel became moist in the inside, 
was covered with a sooty substance %, which Dr 
itley afterwards supposed to be a part of the mer-* 

used in filling the vessel f • 

I the summer of 1181, Mr Cavendish, who hgd 
. informed of the experiments of Priestley and 
hire, set fire to 500,000 grain measures of hydro- 
gas, mixed with about 2t times that quantity of 
mon air. By this process he obtained 135 grains of 

water. He also exploded 1Q,500 grain measures 
cygen gas, with 37,000 of hydrogen gas, and ob- 
;d 30 grains of water, containing in it a little nitric 
From these experiments he concluded that water 
compound. — Mr Cavendish must therefore be con- 
ned as the real discoverer of the composition of wa- 
He was the first who ascertained that water is 
uced by firing oxygen and hydrogen gas, and the 
who drew the proper conclusion from that fact. 
Watt, indeed, had also drawn the proper conclu- 

from the experiments of Dr Priestley and Mr 
rltire, and had even performed a number of ezperi* 



t Mf^, Pmr. 198 1, p. 470. * 1 Priestley, V. .^95 

5 P*;/. Trofis. \Tx\r. ;,32. 



123 OXIDES. 

Book ir. ments himself to ascertain the fact before Mr Cavetf* 
^ dish had communicated his ; but he had been deterred 

from publishing his theory by some experiments of Or 
Pr'estlejy ^hich appeared contttry to it*. He has 
therefore a claim to the merit of the discovery ; a claim 
however, which does not aficct Mr Cavendish, who 
knew nothing of the theory and experiments of that in- 
genious philosopher. 

Meanwhile, in the winter 1781-2, Mr Lavoisier, wiw 
had suspected that when oxygen and hydrogen gas ire 
exploded, sulphuric or sulphurous acid is prodacc4p 
made an experiment in order to ascertpin the fact, at 
which Mr Gengembre assisted. They filled a bottle, 
capable of holding six pints (French), with hydrogeia 
gas, to which ihey set fire, and then corked the bottle, 
after pouring into it two ounces (French) of lime-water. 
Through the cork there passed a copper tube, by neaius 
of which a stream of oxygen gas was introduced to 
support the (lame. Though this experiment was repeat^ 
cd three times, and instead of lime water a weak solu- 
tion of alkali and pure water were substituted, the^^ 
could not observe any product whatever t« This re— - 
suit astonished Mr Lavoisier exceedingly : he resoWedl -^ 
therefore, to repent the experiment on a larger scalps 
and if possible with more accuracy. By means of pipe — 
furnished with stop-cocks, he put it in his power 
supply both gases as tliey should be wanted, that h 
might be enabled to continue the burning as long aa 
thought proper. 

The experiment was made by Lavoisier and La Plac -= 



♦ JhU, Ixxv. 3jOr t ^«f- i'«""' 1781 , p. ^c. 



wateS. 

> the 24th of June 1763, in ihe presence of Messis Chip. 
« Roi, Vandennonde, several oihcr acadeiDicisini, and 
Er Charles Biagden, who informed them ihal Mr Ca- 
Rndisli had already performed it, and thai he had ob- 
luncd water'. They cominued the infiammation till 
in ihcir itocic of gases was wasted, and obtained about 
Jp5 griini of water, which, after the most rigid exami- 
Ution, appeared to be perfectly pure. From this ex- 
periment Lavoisier concluded, that water is composed 
If oijgen and hydrogen. Mr Mongez soon after pcr- 
brmed the same experiment, and obtained a similar re- 
lit: and it was repeated again by Lavoisier and Meus- 
|er on > sc^e sufficiently large to put the fact beyond 
Dolilt. 

Tbc proof that water is a compound of oxygen and Fronfr. 
I^rogen is, that when these two gases, mixed in pro- 
>r proportions, arc fired, they almost wholly disap- 
|nr> and there i% found in their place a quanli[y of 
pri! water, as nearly equal to them in weight as can 
t expected in experiments of that delicate uature. The 
^drogea gas is made to pass slowly from the glass jar 

which it is contained, by means of a tube furnished 
nil % slop^cock, into a gla^ globe filled with oxygen 
k. It is set on fire at the extremity of the lube, ei- 
tr by means of electricity or by a little phosphorus, 
d it continues to bum slowly till the whole of it i« 
ttfumcd. New portions of oxygen gas are introdu- 
i occuionally from another glass jar, by means of a 
b>c famished with a siop-cock. The water, as it is 
Pnted, U condensed in the glass globe. A great nnir- 






t VM. p. 4' 
I 



130 OXIDES. 

Book u. \^QY of precautions are necessary to ensure the puriir of 
the teases, dni to measure their iii(^ht find the nature 
of ihe gas which remains after combustion, ^ut 6x 
these I refer to the account of the experiments theou 
selves^ which h^ve been published bj the Freacb che* 
xnists in the Memoirs of the Academy of Scicaoc** T^ ' 
experiment on which the greatest dependence maybe 
put was made in the year 1190 by Scguin, Foujrcroy, 
and Vauquelin *• The bulk of the gases emploTcd 
in tliis experiment was, 

Yrench In'cbet. 

Hydrogen gas 25980*563 

Oxygen gas 1 2^70*080 

ToUl 38459*643 

The water obtained amounted to 7240*22^ grains 
renchjor j9-iT3grainstroy,or 12'390o£. It exhibited 
no m irk of acidity, and appeared in every respect to 
be pure water. Its specific gravity was to that of di- 
stilled water as 1807L to 18010 ; or nearly as 1*000053 

to 1. 

Tlie residuum of gas in the vessel after eombustioa 
amounted to g87cubic inches French ; and, on being exa- 
xninrd, was found to consist of the following quantities 
of gases : 



a Sffi Avt. df Ckm. Tuj. a^. 



WAtCR. 

Frmcli Inchfit. 
Azotic gas* •-••«• •\»« ••• • 467 
Ctl^boaic acid gas* ••;•••«• 39 

Oxygen gas •••• 465 

B/4rogengas...,^*....».. ^0 

Total. ••....•••;••••• .9Bn 
Now the weight of the whol^ 

gases emplojed was •63P0*71 

That of the water obtained, add 

of the residuum •;. «• 6303*^4 

Or..... ;•••; 3*47 

grains less than bad beep eqiplojred* Tl>iai approaclte^ 
as near an eqa^^ f^ 9%^ be ^i^piect^d in <acperimenta) 
of this natuxe. The small surplus of atotic gas found 
after the combustion caAOpt h^ gqcq^ol^d fot, vnless we 
suppose some commbo air |o ha^o gakfed admission dtt« 
ring the process. 

As sufficient precacrtioos h^d ketti fakcH to p^erertt 
the introduction of earbonic acid gas, the qUantJcj ftmod 
in the residuum must have been formed during th^ pro- 
cess. There mxtiH therefore have be^ « small quan- 
titj of carbon introducvd. Now ^inc, it is supposed^ 
often contains carlikHiy aad hydrogen has the property 
of dissolving carbon ; probably, thcn^ the carbon was 
introduced in this manner. The carbonic acid found in 
-the cestdanA amo imt cd to ^rBQ6 ^;ttiis^ ^hich ac- 
oording to Lavoister^i ddcuUtton^ is CfPApoaeii of A'95|8 
-gftaios of otboD md l4'S4i gratlis of oxfgea^' 

Sobtraetiitg tbete d^S^dB gfuas of cmhou^ tod d» 

- in 



in 

Chtp. r. 



132 OXIBESw 

Book 11. 0*530 of a grain of hydrogen which remuned xn tBt 
vessel, from the total of hydrogen introduced, there 
will remain 852*600 grains for the hydrogen thatdis- 
appeared. 

Subtracting the 14*348 grains of oxygen which en- 
tered into the composition of the carbonic acid, and the 
residuum of oxygen, which amounted to 188*3*71 graiot^ 
the quantity of oxygen that disappeared will amount ta 
5094*6' grains. 

Graint Troy, 
Hydrogen that disappeared 852*7 
Oxygen 5004*6 



Total 5047-3 

Quantity of water obtained 5943*0 \ 



Which i» less than the *) ^ains 

gases consumed by 5 
It is impossible to account for the exact coincideiB< 
of the water condensed whh the weight of the 
consumed, unless we suppose it to be composed of thc9* 
bodies. 

This experiment gives us the composition of wtts^ 

as follows : Oxygen ; . 85*662 grains troy 

Hydrogen 14*338 



100*000 

Dr Priestley, however, who made a great mwaj ci> 

periments on this subject, drew from them a very dii^ 

ferent condusion ; and thought he had proved, that d«- 

riag the combustion the two gaset combme, and that 

the combination is nitric aeid* This theory was adopt- 



L or rather it was suggested, by Mr Keir, who has , trhap-'- 
jnpported it with a great deal of ingenuity *. 

Let us examine these experiments of Dr Priestley f* 
indiee whether they warrant the conclusions he has 
inwn from them. The gases were exploded in vessels 
of copper. He found thai ihe quantity of water ob- 
hioed was alway las than that of the gases which he 
Md used. He obtained also a considerable quantity of 
Hjic acid. In the experiment made on the largest 
paDtity of the gases, and from which he draws his 
Ibclusioas, the quantity of liquid obtained amounted 
I 443 grains. This liquid was examined by Mr Keir. 
I WIS of a green colour ; 12 grains of brown oxide of 
tpper were deposited in it, and it contained a solution 
f nittale of copper (copper combined with nitric acid). 
Lr Keir analysed this liquor : It consisted of pure wa- 
K and oitraie of copper : and Mr Keir concluded that 
keaitiiG acid formed amounted to ^'^th of the oxygen 
ks employed. Here then a quantity of oxygen and 
^dtogen gas has disappeared ; What has become of 
pcm? They have combined, says Dr Priestley, and 
brmed nitric acid. This nitric acid is only ^th of their 
Ifcight. Dr Priestley supposes, however, that it con- 
was the whole oxygen and hydrogen that existed in 
pese gases, and that all Oie rest of the weight of these 
nscs was owing to a quantity of water which they had 
teld in solution. Oxygen gas, then (for we shall ne- 
[ect the hydrogen, which Dr Priestley was not able to 
tiag into view at all), is composed of one part of oxy- 
piaiwl lu of water. Wbcie is the proof of this? Dr 
[iestley informs us, that he ascertained by experiment 



< Kiit** Diitmarj, art. Siti 



\ PbU. Tm»,,l;iS. 



234 MFDIU. 

p^ion n. ^^^^ half the weight of darbonic acid gas tirts pare tr^ 
^ ^ ..■ ^ tcr. Supposing the eiperiment accurate, sorely if eat 
not be concluded from it that oxygen gas consisti c 
a partly or almost wholly of water. It is ItnpossifclE 
therefore, from Dr Priestley *& experiihents, allowing fd 
ingenious suppositions and conjeetures their BffbM 
force, t6 account for the disappearing of (lie tWo gne^ 
or the appearance of the water, without admiTtrng Ait 
ibis liquid is actually composed of oxygen and hy(bo« 
gen. If we add to (his, that oxygen gas can scared^ 
be procured absolutely free from some mixture (^ 
azote, and that his oxygen was always obtained eitbe 
from red oxide of lead, or from black oxide of manga 
nese, or red oxide of mercury, all of which substHlcv 
yield a considerable proportion of azote; if we add, t&s 
it lias been proved beyond the possibility of doubt, aiH 
to Dr Pritst!tY*s own satisfaction, that nitric acid 
composed of oi^ygen and azcte — we shall finditrtOd!= 
ficult matter to explain the origin of th'dt acid ift fiE 
Priestley*s experiments : and if v.c recollect thai in itz 
gnin*s experiment, upon a niuch larger scale than Si 
Priestley's, no nitric acid at all was formed, it willba 
impossible for us to believe th;ic the compcui.d forme* 
by cxygen and hydro*^cn is liitric acid. Thus Dn 
Priestley's experiments rather confirm than destroy tbr 
theory of the ccmpcsition uf uater. We obtain firoai 
them, however, one curious piece of information, ths. 
the presence of copper i::creascs the quantity of nitri« 
acid formed. 

The proof for the composition of water, derived froB 
ihc ccmbu^ticu cf hydrogen ga-s, :> rendered still strong 
er by reversing the exfcnn;?r*. When electric explo 
Mons are ma^ie to pass ihrou^ii v.z'cr, part of it is dc- 
ccmpcscd and ccnv^riji :n:j :::;-.;.:- ^is ar.i hydrogc/ 



Water. 

MesirsVan Trooywyck anJDicman, assisted by 
Cufliberlsnp, fitlwt a small ^lass tube, |tli of an inch 
MiineftT a:;.r t-2 inches long, wiili disiillcd Water. 
! end of iTiTs tube was sealt-d hermcticaUy ; bin at 
ilMc tfme 3 smaTI gold w're had been pas^>ed ilirough 

Anoib'er wire passed ihrough the open end of the 
t', and coiitd be fisL-d at greater or smaller dit 
n the first wire. By means of these wirts, thg 
(^B grear number of elect ricalexlplosionspiisslhrougl 
waier. Bubbles of air appeared at every txplo- 
I, ittA ccflKncd at the top of the tube. When cIm 

ipaiks n'ei^e passed through thio a!r, it exploded 
I ditipptaied almost completely. It mu^l therefor^ 
« consisted of a mi^ilure of oxygen and hjdrogei 
, sad this g;as mu^C have been formed bytlie decom- 
'man of the water t for they had taken care to de-' 
n iht waitr beforehand of all its air, and they used 
!iy prtcauilon to prevent the aecesi of atmospherical 
; md, besides, the quantiiy of gas produced did not 
rinhb, bill rather increase, by continuing to operate 
iiinbcr of limes upon the saiiic water, which could 
have been the case had it been merely air dissolved 
water : nor would atmospherical air have exploded, 
Uefi oDiy a very small rcsiduam, not more than -,'^ih 
I. Tbey had taken care also to prove that the dec- 
I tfUxk did not contribute to form hydrogea gas i for 
pUsing it through sulphuric and nitric acids, the 
idoct was not hydrogen, but oxygen gas*, 
these experiments have been since repeated by Df 
irson, assisted by Mr Cuthbcrlson. He produced, 
means of electricity, quantities of gas from water, 
t to 56-5488 cubes of Vs'h of an inch each ; on 



m OXIDES, 

Book IL nitrous eas bcinr; added to which, it suffered a dimino- 

tion ox bulk, and nitrous acid appeared to nave oecn 

formed. It must therefore have contained oxjrgen gas* 

When oxygen gas was added to the remainder, and an 

electric spark passed through it, a diminution took place 

precisely as when oxygen and hydrogen gas are mixed : 

It must therefore have contained hydrogen* When to 

elecric spark was passed through the gas thus prodiu 

ced from water, the gas disappeared, being, no doobli 

converted into water *• 

Such are the proofs by which the component parts of 
water have been ascertained. If we consider them at- 
tentively, and compare them with a vast number of 
other chemical phenomena, all of which tend tocoofinn 
and establish them, we must allow, I think, that scarce* 
ly any physical fact whatever can be produced, which 
is supported by more complete evidence* There ue 

I 

indeed some galvanic phenomena which scarcely seem 
compatible with it ; but the nature of this singulir 
power is still too imperfectly understood to warrtnt 
even a conjecture concerning it. 



11. COMBUSTIBLE OXIDES. 

The oxides formed by all the simple combustibkiy 
except hydrogen, are combustible, and of course cannot 
be formed by combustion. The composition of these 
oxides is still imperfectly known, owing to the extreoie 
difficulty of examining them^ 



^ Nicholson*! Jwr, i. a4». These expcrimeots are now nude wkh 
freat cate hj the galfanic ^paratus. 



OXIDES (^-CARBOK. 



OXIDES OF CARBON 



Opinion st present pr«tt; generally admitted by 
Aftntsts, that carbon is capable of uniting wiih at least 
two doses of oxygen, and of forming two conipounds, 
one of which Is an oxide, and one an acid. The oxide is 
Loricnic oxide, which is a combustible gas. A short 
sketch of the properties of this oxide has been given in 
a preceding pari of this Work. But it will be neces- 
Aary here to enter more into detail. Besides carbonic 
exidt, it was supposed, from the expcrimenis of Mor- 
-veau on the diamond, that there existed another oxide 
of carbon, containing a smaller proportion of oxygen, 
Knd that this oxide was nothing else than pure charcoal. 
But the late experiments of Messrs Allen and Pepys, 
by demonslrating the inaccuracy of Morvean's experi- 
nieais, have destroyed the evidence upon which that 
supposition was founded. We are at present ignorant 
of the composition of charcoal, though it has been de- 
jDoitttrated that it contains at least two ingredients, car- 
bon and hydrogen. Till the composition of this sub- 
stance be better ascertained, I shall allow it lo retain the 
plftce in the arrangement of chemical substances which 
ym assigned it when it was considered as an oxide of 



13# crxmEs 

bmI it.* 
Pmfrm IL j^ Qy Charcoal and Carbonous Oxide. 

Before the experiments of Morveau on the diamond 
were made known, chemists were accustomed to con- 
found together carbon and charcoal^ though they had 
been carefully distinguished by Lnvoisier who indeed 
invented the term carlon^ to render it more diflicult to 
mistake for charcoal, the substance to which ht: ap. 
plied it. After these experiments beeam^ knouts ^he« 
snisii fell into the rew mistake of oovrffHUiAni^ etitreotl 
^ith carbonous oxide^ till ih\% errov was hi sibiMe fatfU 
sure} rectified by Crnicksharnks ftA^ B^tthoitef, and tiR 
the experiments of AUe» and Pepya deafkCHistrated iff 
inaccufacy. 
Twotpe- I* Wbe6 chareotl is pTrpafcd rd thd iiluid Wa)", \^ 

^^olucw!T c«po«^ ^o^ i" close tcssets to a rtfd h^»f, it tlwa^ 
int»n contains a portion of hj^drogen : For if a qiiaritity of 

Ibis charcoal be exposed to a strong ht:^K- ii> ^r^tbrtof 
porcelain, iron, or coated glass, a grent^nanriljf of ga 
is obtained* The gas which comes ovt-r fir&^ is a miX'* 
tnte of carboDic acid aid leavy fr.flpmmable ^as ; Imi 
tbe proportion of carbonic acid dimftrishes, and af last 
it ceaaea to come over at all ;. yet the inflammable gas 
fOBlinu^s as copious as ever *. 

The evolution of these gases was long ascrrbetf 6^ 
chemists to the water which charcoal uaoaily ccitCinM^ 
and which it is known lo absorb from the atmos^htt^ 
with considerable avidity. If that were the c4se, iKi 
proportion of inflammable gas ought to dimtrtish at ikt 
same rale wiUi Iho carbonic acid ; the hydrugea of Ihtt 



* CrukkshaLkf, Nicholson's J^nmal^ 1S02. v. 210. 



OT tfxKttnT, ISA 

one being equally dctived from ihc decom position of Ch'p- L 
Water whh the oxygen of the otKer, But as the crvolu- ' 

Hon of indammabic gas caniinties after thftt of carbonic 
itM has ceased, it is scarcely possible lo deny, that the 
bjnfttigvn which thus escapes constitUKd « cofopencM 
ftn oT th4 charcoal. 

2- When common charcoil is exposed for an hoar And prtpa* 
Ittadose crociWc lo the strongest heat of a forge, it " ' 
ceases to emit gas -, and no tcmperaiure is sniBcieot to 
cxpcl gas from charcoal thus treated *. Desormes and 
Clemcot have endeavoured to dtmonstraie, thai by this 
treatment common chnrcoal is deprived uf the whole 
of hi hydrogen. They pnt a quantity of charcoal, rc» 
«mly exposed to the heat of a forge, and not yet cold, 
xnto the middle part of a long glass tube. To each ez* 
treority of the tube was fixed another tube, filled witb 
dry mirimt a/Stne, and surrounded with a tnixiure of 
Snow and salr. To the exircmiry of one of these tubes 
WU fixed an empty bladder; to ihc extremity of the 
other, a bladder containing a qiianlily of oxygen gss. 
TTic charcoal was healed to redness by placing the 
tube in ft furiiace, and then the oxygen gas was made 
fo pass slowly over it from one bladder to the other. 
By this contrivance the charcoal was burnt, and con- 
verfld into carbonic acid. The oxygen gas, in passing 
ihrough the muriate of lime, was made to deposite the 
inoisiate wluch it contained, and the proportion was 
luiowit by the increase of weight of the muriste. If 
ibe charcoal contained hydrogen, water would be form- 
ed during its combustion, which would unite vith the 



• 0<:>oimcsind Ckiamt, Aw. Ji Cllm.xaix. t 



140 OXID£S 

l)^^t?l( ^^''^^^ ^^^^ formed. Bat this gas would deposite iti 
< ■ V ^ moisture during its passage through the muriate of lime, 
at the other extremity of the tube, and the increase of 
weight which this muriate would experieoce would iiu 
dicate the proportion of water formed during the pro- 
cess. In both cases the muriate of lime was increased 
ia weight 0*02 parts. Were we to suppose this is* 
crease owing to the formation of water, the small qnan- 
tity would only contain hydrogen to the amount of 
TyVv of the charcoal ; a portion too small to be re- 
garded **". 

The same chemists tried the combustion of charcod 
obtained from a variety of other substances exposed to 
the he^^ of a forge, as pitcoal, animal substancei^ and 
various vegetable substances, and found the products 
exactly the same. Hence they conclude that charcoal 
is in all cases the same, provided it be exposed to m 
strong enough heat. And they conclude, too, that b 
this strong heat the whole hydrogen of common char- 
coal is expelled. 

But this is gobg rather farther than their experiments 
will warrant ; and it is directly contrary to the experi- 
ments of Cruickshanks, who always found gases ob- 
tained by means of charcoal, in whatever state, to con* 
tain hydrogen. Besides, BerthoUet has pointed out 
circumstances which render the precision of these chc* 
H^sts somewhat doubtful. 

Both con- ^' ^^^^ *^^ the facts at present known respecting th^ 
tain lome composition of charcoal. They enable us to conclude 
>urogcn. ^^^^ ^^^^^ ^^ ^^^ species of charcoal, namely, common 



• Aim, J§ Cbim* llii. laS. 



*ad f>rrpared charcoal. The first contains at least two Chap, r, 
ingredients, carbon and hj/drogen ; the second is de< 
prived of a portion of its hydrogen. Ti consists chiefly 
«f caTbon ; but it still retains a small portion of hy- 
drogen, lod is not, therefore, strictly speaking, pure 
carbon. 

4. When the diamond is exposed to the action of 
heat snd air, it has been observed by different experi- 
cncntcrs to acquire a black coat not unlike charcoal. 
Tliis coat may be considered as a combination of carbon 

ftnd oxygen; it is perhaps carbonous oxide in a stale of 

purity. Whether any similar combination exists na- 

m.ive has not yet been ascertained. 

II. Of Carbonic Oxide. 

The substance at present known by the name of car. \ 
^otiic oxide, is a gas which had been confounded with 
carbureted hydrogen, till Dt Priestley drew the atten- 
Koo of chemists to it in a dissertation which he pub- 
lished in defence of the doctrine of phlogiston. His 
*3cperiinents were immediately repeated, and his opi- 
nions con6rmed by Dr Woodhousc of Pennsylvania. 
But the real nature and composition of the gas was 
discovered by Mr ,Ciuicksh^nks of Woolwich, and the 
discovery communicated to the public in 1S02*. A- 
bout the time of the publication of Mr Cniickshanks' 
disscfUtion, the experiment of Woodhouse, which he 
tiad transmitted to France, engaged the attention of the 
National Institute. Gnjton Moiveau, who had been 



242 OZII>EB 

iJ?25ii'n ^PP^'*^*^'' ^® S*^'^ ^ detailed account of these ezperi'* 
< g - metitSy en^ftged Clement and Desormes to investigate Ae 
subject ; and these gentlemen were gradually led to the 
same conclusions* which had been previouslj drawn bjr 
Cruickshanks. The subjectin the mean time attracted Ae 
attention of Bertholet, whose experiments induced him 
to form a different opinion respecting the compotttioo 
of charcoal and carbonic oxide from that which hid 
been entertained bj the other chemists. This opiaioo 
he supported in three elaborate dissenations» pviUiihed 
n the fourth volume of the Memoirs of the Netioml 
Institute ; in which he examines the eJ^perimeatSi sod 
combats the conclusions of the other chemists, with hu 
usual sagacity. About the same time a dissertation was 
published by the Dutch cbcmtsts^ contradicting the ex- 
periments of all other philosophersi and affirming the 
real results to be very different f . This short historical 
sketch is a suf&cicnt proof of the great difSculty atteod- 
ng the investigation. No less than four different opi* 
ntons h:ive been maintained^ and every one of them bj 
men of^ eminence, of acknowledged skill, and undoak« 
ed candour. 
Prepari- 1 • Tliere are four different processes by which carbo* 

tioa. j,jg oxide gas may be procured : Firsts When a mixtufc 

of purified charcoal and the oxides of iron or zinc, or ia- 
decd of any oxide capable of bearing a red heat, is expo* 
sed to a strong heat m an iron retort, the oxide is gradv- 
ally rcd;ict:f',and during the reduction a great quantity ef 
gas is cTolved. This gas is a mixture of carbonic acid 
gas and another which burns with a Uue flame. It is to 



* ilair. di Chim. waa. S8. and lUl isr. f Ibid, zllli. i rj. 



mi* llAt ihat the term carbonif oxUt lias been applied. 
nlu cviMnic acid tmy be separated \>y passing ttie gas 
llirougb lime-waier. Mr Cruiksluiiks tmd in this way 
|be oxides of iron, xinc, and capper, litharge, and the 
bUok oxide of manganese. The following conclusions 
Mtwll firoro his experiments: ThuM oxides which part 
villi tfeilir axjgen mou readily yield the greatest pro- 
penion of carbonic acid ; those that rcuia llicir oxy- 
fcn most obstinately yield the greatest proportion 
•f cafbonic oxide. Il is always towards the begin- 
niog «f the pfooeM that the greatest proportion of car. 
bonic *cid gas comes over ; it gradually dimiiiishes, 
ud U Ibm nothing but carbonic oxide is disengaged *. 
The results obtained by Clement and Desormcs coin- 
tide almost exactly with the exj'erimenis of Cruiksbanks. 
Sut they laiislied thcoiselves with the while oxide «E 
iim^ vilhoul uying those of other metals. They 6ub- 
ganini plumbago fw ^burcoal, and obtained the &une 
r«Mlti+. 

\ Settml, When a miuiue of mie part of purified char- 
Bwli fJid three p^irtaof the carbonate of lime, or of stton- 
tian, or of baryics, is exposed lo a itroag heat in an iron 
KCtOri, the earboiiic acid i:i gra«lually separated or dc- 
pOted, aitd gas is evolved in abiindajice. Thix gas 
I ot a nuxiure of abwui one pari of carbonic acid 
pans of carbonic <>^-id« %• In this case a por. 
Uic carbcQic acid ot liic carbonate is disengaged 
ed, but the greatest pure of it is converted into 
oxide by tlie action of the charcoal. 



*• Acr. tSct.v.s. ( j(«. <fr. ClMi.ittii- j]- 

>, Ibid. 45' 



144 0SIBE3 

-?^!^ "• Thirds When a mixture of equal parts of any ot the 
< ^ ' three above-mentioned earthy cari>onate8 and demn iroa 
filings is heated strongly in an iron retort, the carbonic 
acid is decomposed in like manner by the action of the 
iron, and the very same gases are procured In great a- 
bundance. Dr Priestley first tried this method witk 
the black oxide of iron and carbonate of baryrii ; but 
when Cruickshanks substituted pure iron, the gaseous 
product was considerably increased *. 

Fourtlp When carbonic acid gas is made to psis 
slowly and repeatedly through prepared charcoal betted 
to redness in a porcelain or iron tube, it gradually dis- 
appears, and carbonic oxide is found in place of it^ 
Here the charcoal decomposes the carbonic acid pre- 
cisely as in the two last cases, with this difference onlj, 
that it is in a gaseous state, whereas in them it was com* 
bined with a base. This experiment was first madebj* 
Cruickshanks f, and afterwards by Clement and De* 
sormes t« 
Hmr pun- g. Such are the different processes for procuring car- 
bonic oxide. From the experiments of Cruikshankf 
we learn, that the third method is the only one to be 
depended on for obtaining the gas in a state of purity.- 
If equal parts of chalk and iron filings, previously ex« 
posed to a red heat separately in close vessels, be mixed 
together and strongly heated in an iron retort, the gates 
which come over are merely a mixture of carbonic add 
and carbonic oxide ; and the first being abstracted by 



• Nicholion't/ji/r. i8oi. v. 4. and ^oK f thid. p. 209. 

t Aim, de Ch m, xxxij. 4^. 



OF CAXBOK. 



145 

Ch»p.L 



Btt oT lioM-tfater, the carbonic oxide gas rcn 
Me of purilj'. 

I. Carbonic oxide gas, thus obtained, Js.inviaiblc and ^"'t^*^"- 
idc like commoD air. Its specific gravity, according 
the experiments of Cruickthanks, is 095 S, that of 
being 1 000. It is to common air as S2 to 23. One 
Idred cubic ioches of it weigh 30 grains. The re- 
ll obtained by Desormes and Clement does not differ 
Kh from this *. 

^ioials cannot breathe this gas without suSocaiion. 
da put into it by Desormes and Clement droptdown 
■t before Ibey had time to lake them out ; and when 
f attempted to breathe it themselves, the consequent 
k giddiness and faintness +■ Neither will any com- 
Itible body bum in it. 

[t is not altered by exposure to light, nor by passing 
trough a red hot tube. From the experiments of 
traent and Desormes, we Und that it is dilated by 
it exactly like common air, as was indeed to be ex- 
ited. 

1. Carbonic oxide gas is combustible. It takes fire Combuii- 
the open air when it comes in contact with a red hot 
If, or when it is presented to the flame of a candle, 
1 bums with a lambent blue flame. When mixed 
lb common aii before it is kindled, it bums more ra- 
(jriod brilliantly, but does not detonate. Thecom- 



Vf uku^ ■ mean at their eiperimciiti, vt obriia the height of ■ 
■fgv 1*135 fmnoits, which reduced to our itaniUtdgiiei the weight 
10 cubic inchei 1E7 graini. Their roull woutJ hi*c been Mill 
irCriukibanlii', had 1 ei<latleil their triiti with tome ofthelljht- 
Id impnrcK {IKS which they obtiiacd- 
I*ir.*ato.iiiij.j4. 

fW. //. K 



149 OZIfiES 

Book IT. bastion if stfll more rapid and brilUaol if we tofeftittite 

Division II. • c • -J 

< y ■ > oxygen gas lor common air. Sometimes it detooatet 

with oxygen, but moal commonly th« detooaUoa docs 

not take place. 

From ^he experiments of Graiekihanktt which have 
been confirmed by those of Clement and Desormtii we 
learn that lOO^oabic inches of carboaio oxide, in onkr 
to undergo complete decomposition, mtMt be mixed b». 
fore combustion with 40 cubic inches of oxygen gas; 
and this mixture, being exploded by electricity in ade- 
tonating tube, is converted into 95^ cubic inches of eir- 
bonic acid gas. Or, in numbers, 30 grains of oarboak 
oxide require for saturation about 13*6 graias of oqr. 
gen ; and tlie resulting compound amounts: to- 43*0 
grains of carbonic acid gas. No sensible qoaotily of 
water is formed by the combustion of this gas when it 
is procured by the third processi and made a« dry- aoi 
pure as possible before the experiment.. 
Action of .'V* This gas has no mrtibn whatever upon thoaioifle 

b"aublc«!>"*' combustibles at the common temperature of the atmos- 
phere ; but its RCttviry is somewhat augmented by the 
assistance of heat.. 

When passed through melted smlphnr, it does not 
combine with it, nor alter its properties ; but i% dis- 
solves a little phosphorus, and acxjuires the properly of 
burning with a yt'llow flame. When pas<wd thrcmli 
red hot charcoal, ii dissolves a part of it, if we believe 
Desorincs and Clement^ and its specific gravity is in- 
creased, 'fhe same chemists affirmed, that when a 
mixture of carbonic oxide and hydrogen gas is made to 
j^ass through a red hot glass tube, charcoal is deposited^ 
which lines the inside of the tube with a shining eoaiMl ;, 
tliat water is formed, and bydrog^eo^ seemingly pazTy 



or carbok; 14^ 

disengaged from the other end of tte tube *• Biit ^ C^ \ 
when this experiment was repeated by Saussure junior, 
he found that the supposed . enamel of charcoal was 
mereljr the black, (or rather bluish) colodr which flint 
glass acquires when hjdrogen is brought in contact witK 
it at a red heat, as had been previously observed bj Dr 
PSricstlcj +• Indeed' it is very unlikely that hydrogen 
gas is capable of decomposing carbonic oxide ; as Saus- 
sure has shown, that wnen carbonic acid and bydrogeii 
gas are made to pass through a red hot tube, the acid is 
decomposed, and carbonic oxide produced — a result 
which has been even confirmed by the subsequent ex- 
periments of Clement and Desormes; 

6. None of the simple incombiistibles produce ^^'Ijy"*' 

oosudwm 
any change upon carbonic oxide at any temperature 

hitherto tried ; but the action of oxymuriatic acid gas 

upon it is extremely curious add important; For the 

investigation of this part of the subject we are entirely 

Indebted to Mr Gruikshanks, whohastliereby disclosed 

to chemists a new and valuable method of trying the 

purity and composition of the combustible gases; 

If a phial be filled with a mixture of tw6 measures Ofoiynwi- 

of carbonic oxide gas and 2\ measures of oxymuriatiC 

aeid gas X^ then closed with a ground Stopper, and aU 

lowed to remain for 2\ hours with its modth inverted 

tinder mercury, on drawing the stopper under water, 

two-thirds of the gas are immediattly absorbed, and all 

the rest by agitation in lime-water (except -J-th of a 



* Amm. dt dim. zxxi?;. 6t. f Jwr. de Pbyu !▼• 396. 

t Procured b^ pourio^ muriatic acid on the by^croxymuriate-oCpot* 

K2 



148 



OXIDES 



Sookir. 

DiTimoo If. 



Of mcCilif 



Aikaliet 
And earthi. 



measure of azote) *• Hence we see that theie tw# 
gases act upon each other at the teoiperatore of the at- 
mosphere ; that the carbonic oxide graduallj abstracts 
oxygen from the other gas, and is converted into car- 
bonic acid. The oxjmuriatic gas thus decomposed is 
converted into muriatic acid, which is inataatlj ab* 
soffbed on the admission of water. Thus bj the ao^ 
tual action of the two gases, the whole is converted 
into carbonic acid and muriatic acid. 

Mr Cruikshanks ascertained that this mixture of car- 
bonic oxide and oxymuriatic acid gas does not bun 
when electric sparks are made to pass through it, nor 
IS its nature altered ; whereas a mixture of carbureted 
hydrogen and oxymuriatic acid gas explodea immedi- 
ately . This difference enables us to distinguish cathi- 
reted hydrx>gen from carbonic oxide with the greatest 
facility f. 

7* From any experiments hitherto made, it does not 
appear that carbonic oxide is capable of acting on the 
metals ; but Clement and Desormes affirm, that when 
passed hot over the red oxide of mercury, it produces s* 
commencement of reduction.. Indeed it is^ very likdy 
that it will be found capable of reducing several of the 
metallic oxides, especially those that part wkh their oxy- 
gen easily, 

8. Neither the fixed alkalies nar the earths have aay 
action on carbonic oxide. Neither does amoMMiia alter 
it when passed with it in the state of gas through a red 
hot tube t. 



* Nicholson*! Journal, l8oi,T. p. SO5. 

t Ctemeot' and DeiMinet, if ««. dt Clim. xxzix. 6t. 



t IBid. p. 907. 



OF ZAKSO'a. 

d. From tlic history of the properties of this gss just 
j^iven, it mutt be obvious at once, that it contains car- i 
bonuxn ingredient j for when Bred with oxygen, it ' 
jields carbonic acid gas as a product. That it differs 
trom carbureted hydrogen is obvious from its speciilc 
gravity, from the action of oxymuiiaiic add gas, and 
from the result obtained by burning it. As it yicJds on 
combusuon no perceptible portion of water, it was con- 
cluded by Cruikshanlts, and afterwards by Guyton 
Morveau, Desormes and Clement, that it contained no 
hydrogen, and contained no other combustible base be. 
sides carbon. But it requires much less oxygen gas for 
combustioQ than charcoal. Thus 1 00 parts of char- 
««al require 257 parts of oxygen to sattirtiie ihem ^ 
whereas 100 parts of carbonic ovide require only 45^ 
parts of oxygen ; and in both cases carbonic acid is pro- 
duced. This remarkable difference can only be ac- 
counted for by supposing that the carbonic oxide is al- 
ready combined with a portion of oxygen, and there- 
fore a smaller addition must be sufficient to saturate it. 
Accordingly this was the consequence drawn by Cruik- 
shanks; and it is impossible to resist the evidence in 
favour of his conclusions. The gas therefore, accord- 
ing lo this reasoning, is a compound of carbon and ox- 
ygen. Hence the name earbonic oxide given to it by 
eliemists. 

If we suppose, according to the experiments of Lavoi- 
ucr, that carbonic acid is composed of 2B carbon and 
12 oxygen, and consider the experiments of Cruik- 
sbanks as approaching to iccuraey, it will be easy for 
QS to ascertain the component parts of this oxide. 

According to Cruikshanks, aograins of carbonic ox- 
iM combine by combustion with about 13*6 grains of 



r- 4 



l)noV ir. pxy£fn. and the carbonic acid formed axnoaotf to a. 

bdit 43*6 graini. Hence it follows, that carbonic add 

i& compob^d of about 

f)9 carbonic oxide 
31 cxj'gen 

100 
But ]0(^ carbonic acid are composed of 72 oxygen anj 
28 carbon. We have therefore this equation, 

Cirbrr. Ox)griu Cirb.Ox. Chy|^ 

S8 -f 12 = 6P + 31 
Cirlxir. Oxyv^n. Carb. OskI«» 

28 + 41 rr 60 
That is to sar, to parts of carbonic oxide are conu 
pi)M.dot'S8 yxkxs of carbcii and 41 of oxygen* Of 
courae we have/#r cent, pboi:t 

41 c;irbcn 

5n cxvgen 

J CO carbonic oxide 

And ICC pnt« cf cat ben united to 146 of oxjgcn fbfii 
'i^K of carbonic ox'de. 
*n.r<*-r<i| B^^ ^ ^^^' statrn-.ent has been called in question by 

)knhg£et. Bert' o'^ • According to ihisb sagacious phijosophcr. 
thertr m^e two diSlrent species ot iiiflammablc gases 
containing carbor« lite nrst »pccie> is composed of 
C3ibon and hxoroic^n ; the seccr.d^ct carbon, hydrogen^ 
and Qx%ger» To disvp^j^otyh thcMr rwo speciea from 
im.:> ot>.er9 be c^Iis the £is: r^rrf ar^ m ff^o^oi ^- the 
STv'cad (.t.^urif^^m'CiJ I^turc^tttm To :he first species 
belcfftg :be ^asrs cburjcc b_. pas$:rg alcohol through 
a resl hot tub«» bv ci5i'!rr^ ^i\ adhj cxpcsirg moiac 
cb^xccd tv.^ i irc ^ . a\ ^^c. To :'e wc^rc >p«ues be. 
Iv::^ ;ic ^4^ ^ «x.uicd bv c^fC^-;.^ <:^ :rwc;kl :o a auong 



OFCAUOX. 

heftty the gas obfainexl bj distilling smgar, the gas des- 
crib=>d n ihis dc iow undei the n^ime of carbonic ox- 
ide, &.C. There are maoj varieties of these gases, dif«* 
fering from each other in the proportions of their in- 
gredieats : and the gases belong ins; to the first species 
majy by v;^rious processes, be converted jnto the se* 
cond. He calculates the proportion of hydrogen in car* 

« 

bonic xaude to be about Vr^^ ^^ ^^^ whole. 

These conclusions are obviouslj irreconcileable witli 
the czperiinents pf Cruikshanks and of Desgrmea mad 
Clemeat| and cfMipol^ therefore be admitted without 
very decisiTe proofs. . The carbonic oxide pb^^^ined by 
Cruikshanks, when as pur^ as possible, yiekh^ no pe^* 
ceptible quantity of water when burnt with oxygen* 
But Berthollet.obserycs.t^at all gases contain water as 
a.voastitttfnt part, afxd .shows that al} thewater that 
coiuld have been ^med^ would have combined with 
the carbonic acid gas, and remained invisible. Even 
if we were to grant this, and to allow that some water 
has been formed in every case of iiie combustion of 
carbonic oxide with oxygen hitherto tried, still Mr 
BerthoUet's hypothesis woukl stand upon as weak 
ground as ever. For it is obvious from the experi- 
ments of Cruikshanks, that the drier he made his ma- 
terials the purer was the gas, or the less water was 
formed during its combustion ; and when he employed 
bodie^ that could not contain any hydrogen except in 
the state of water (namely, dry chalk and tin or iron), 
the gas was obtained purest of all. 

Mr Btrthollet's chief reason for affirming that car* 
bonic oxide must contain hydrogen is its small specific 
gravity. The specific gravity of 

oxygen gas is 1*103 




(5f OXIDES 

Book IT. carbonic oxide 0*956 

cmrboQic acid 1*500 
The specific gravity of cari>on is undoabtedlj miicb 
greater than any of the three. Now when oxygen gis 
combines with carbon, and forms carbonic acid, its 
specific gravity is increased, as happeiu in olher cases. 
But how is it possible, says Berthollet, to conceive that 
the addition of carbon should diminish the specific gnu 
vity of oxygen gas, as would be the case if carbonic ox* 
ide were composed of these two ingredients only ? Nay, 
carbonic acid, by dissolving an additional dose of car- 
bon, would not only become specifically lighter thsa 
before, but even specifically lighter than oxygen gai^ 
which Berthollet considers as incredible. But this res* 
aoning is by no means sufllicient to induce us to refine 
credit to the conclusions of Gruikshanks ; for stnilsr 
instances are by no means so uncommon as BertboDet 
supposes. Mr Davy has given us an pxampk whidi 
has some analogy to the case under our considcratioa*. 
The specific gravi^ of oxygen {[as is 1*103 

azotic gas 0*985 
nitrous oxide 1*603 
nitric oxide 1*004 
Now when nitric oxide is converted into nitrous oxide 
by abstracting a portion of its oxygen, the heaviest of 
its component parts, its specific gravity ia increasd. 
This is as great an anomaly as that at which Mr Beiw 
thollet startles. 



* Joumalt •fth9 Rwjti ItuiiiMihH, I 317. 



tar vjhvmn. £Wd Aospbokus. 



OStDES OF SULPHUR AND PHOSPHOKtS. 

C ongbt DOW to proceed lo the consideration of the 
es of sulphur and phosphorus, which constitute (he 
linder of the oxide supporters; but these bodies arii . 
loo unperfecdy known to adroit of' a scpuiatf dis^ 
on. The smaJl number of facts which have been 
taiocd were detailed in the tir» Book of this Work, 
B the Eubitances themselves, which constitute the 
I of these oxides, were under examination. 



OXIDE SUPPORTERS 



HE oxides whose bases are the simple tncombusti- 
cannot be formed by combustion, but make theic 
ftnmcc in processes nearly the reverse of combust 
{ aod hence it happens that the oxygen which they 
tin is still capable of supporting combustion. Che- 
B have given the name ot oxide to those oxides onlj | 
K base is azote i the oxide of muriatic add h 
considered as an acid. This will prevent us from 
ig it into consideration in tbts Chapter; but a 
;h of some of its most important properties wu 
1 we were treating of its base. 



iS4 0xnMs 

Bbokn. 



lioo 



SECT. IV. 

OF THE OXIDES OF AZOTE. 

A.ZOTE and oxygen form twodifferent oxides, both of 
which were discovered by Dr Pr]<;si^ej. Thejr tm 
00I7 be exhibifed in the state of a gas: Hence the first 
of them has been called nitrous oxide gas ; the aecoody 
nitric oxidt gos. 

I. Krraovs OkrDt Gas* 

f 

lll^^_^ Nitrous oxide gas was discovered by Dr Priestley 

about the year 1*76, and cailed by lim iicfh*ogisticaUi j 
nitrous gas. The associated Du<ch chcn ists l^amlrifd 
it in 1793, and dcmotistrattd it to be a compciii.d of 
azote and oxygen *• But for a full in\estfgaticn of its 
properties wc are indcbief* 10 Mr Davy, viho pub^sbed 
an excellent dissei ration on it ^n tbe year 1800. He 
gave it the name of nitrous oxide \. 

Prfpin- 1. It maybe procured b) the following process: 

Take any quarrity of nitrate of amnionia (a salt compo- 
sed of nitric acid and ammonia) in crystals, and expose 
it in a retort, by n^eans ot a lanip, to a heat not uc^cr 
340^, nor above 600**. It nn-Its r&pidly, and is it* 
composed, emitting a great quantity of gas, which is- 



• /»iT. A Phft, tlii. 3S3. 

f Sljisettr^bes^ (bUfy con£:r'.img \i:rstBt Cxidc, 



From ihe mouth of ihe rclort, ard may be receiveil ^^ 
IM JMi in the usual tnaniier. Tlie gas which 
a over it mtrouj oxiJf. This process was first 
cd out b? Bt^rthollci ; but it vru much simplified 
Ir Davy*. 

Nitrous oxide gas, thus obtained, has all theme- Prop 
leal properties of air : but it is much heavier than 

its tpeci5c grRvily, according (o Davy, ix 1-603* 
[>f air being I'OOO. it i» to common air nearly as 5 
K One hundred cubic inches of it, at the tconpe- 
vofaO^t barometer at 30 inches, vreigh 4U'70O 



is capable of supponing combusiion even better 
comincii atr ; dmo^l a&wel] iiidted as oxygen gai. 
ndie burns in it with a brilham H^tnc aud a crack- 
Doisc. No combuslibU-, however, burns in il, on- 
il be previously brought to a state of ignition, 
r Priestley and the Dutch chemists had concluded 
it cannot be respired ; but they did not examine it 
Stale of purity t- Mr Davy ascertained that it 
be brcaihed for several minuies without any bad 
ts. The feelings produced by breaihtng it bear a 
g resemblance to inioxicaiioti ; but they are not 
■Kl by that langour and debility which is a con- 

Itr TrMiM ]»f TcmiAtii, very juilji, thu the gu which comet 
I Ae btginnini; gf ihc pniccM diffcri a little &gin niiroui ou'dc, 
lit iHBil mlrvm tm. 

r Ptieulcj iBiIecil fautii, in dd£ in^iuicc, that > mouM brcithcd il 
poult* withiiut uncuiui). In ihia npciicocnt lie kcuu is bav: 
" 'fi Ddrlf pure.— Primkl.ii. 8^- 



456 OXiDfeS 

Bof>kiT. stant attendant of intoxication *^ It cannot be breathed 
" longer than about four minutes, without the Iota of to* 

luntary motion altogether. When animals are confined 
in it, thej give no signs of uneasiness for some mo^ 
ments ; but thej soon became restless, and, i£ not r^ 
moved in a very few minutes, die altogether* Hence 
we see that, though this gas be respirable, it ia mach 
Jess so than common air or oxygen gas t« 
Action of .3. This gaseous oxide is absorbed prettj repiAj hf 
water, as Dr Priestley ascertained. 



toted. Water absorbs 0*86 paru of its bnlk of this 
gas, or according to Dalton nearly its own bulk of it. 
It acquires a sweetish taste $ but its other p r o pe rti es do 
not differ perceptibly from common water. The wbok 
of the gas is expelled unaltered by boiling the water}. 



• Mr Divy tocrilwi dM«ffeeu it ha4 upon JuoiMlbaogit: "Hi. 
▼ing pftvioutly doted my DottrUp and eihuwitcd my hft^ I bRMM 
four qnartt of nttrout oiide from a^ ^co « tUk bag. The fint ktiStp 
were stmihr to thote produced in the hit ei^eriment (giddioeii) ; bit 
in leH than half a minute, the rtsptratioo hekig contiotted» fhrj ilnilniA 
cd graduaUy» and were succeeded by jcnmtioiy uiafogfom t*gcaik 
pretrare on all the muaclet, attended by an highly plea^jureable thnlfii^ 
particularly in the chest and the extremities. The objects afound me |^ 
came dazzling, and my hearing more acute. Towards the hpc wgfin^ 
tions, the thrilling increased, the terme of muscular power became grett^ 
er, and at last an irresistible propensity to action nu indulged to ; 1 1^ 
collect but indistinctly what followed ; 1 know that my mocioBW me 
various and violent. 

** These effects very toon cea^ after respiration. In ten mimitest 
had recovered my natural state of mmd. The thrilling in the ezticmi- 
ties contimei longer chan the other sensations.*' Davy's Rftemrditff, 
457 . The gis has been breathed by a very great number of pertoot, and 
aknoit every one has observed the same things. On some few, indeed, it 
h»s no effects whatever, and on others the effects are always painful 

] Davy*« Resetrsktif p^ 94. J Prieitlfy, ii. 81. 



r^ 



OP AZOTE. 197 

Wbea this gas combines with the water, it expels the Chap. 1. 
common air which was Formerly dissolved in the water. 
Hence the residuum of common air, which always ap- 
pears when Ibis gaseous oxide is exposed to a suflicient 
qnantjlj of water *. 

4. This gas is not altered by exposure to Ught, norio 
ioy heat below ignition; but when made to pass through 
■ red.hot porcelain tube, or when electric sparks are 
made to traverse ihisgas, it isdecomjiosed, and convert- 
ed into nitric acid and common air f. 

5. There is no action between this gas and air or 
oxjgcn gas. 

6. Sulphur, at the common temperature of the air, is Ofihetim. 
not altered by this gas. If it be introduced into it while tibln. 
barning with a blue flame, it is immediately extingiiish- 

ed ; but if iatioduced while burniag with s white flame, 
it oODtiaues to burn for some time with great brilliancy, 
mud with a Ene red flame. The products arc sulphuric 
add and azote. When about the half of the nitrous 
oxide is decomposed, the sulphur is extinguished % . 

Phosphorus may be melted and sublimed in this gas 
without alteration ; it may be even touched with a red 
hot wire without undergoing combustion ; but when 
tooched with a wire heated to whiteness, it bums, or ra- 
dier detonates, with prodigious violence. The products 
are, aiotic gas, phosphoric acid, and nitric acid : a part 
of ibe oxide remains undecomposed |[. 

Charcoal, conSned in this gaseous oxide, may be 
kindled by means of a burning-glass. It coatiaues l» 






ISft 



OtTDEB 



Bookn. 
Dnriiion 11. 



Of the me* 



AtOtites. 



Imrn with great brilliancy^ tifl about the half of the gas 
is consumed. The products are carbonic acid gas and 
azotic gas ^« 

H]rdrogen gas and nitrous oxide gat detonate violent- 
ly with a red flannel when a strong red heat is applied^ 
Of when the electric spark is made to pass through the 
mixture. When the proportion of hydrogen is nearly 
equal to that of the oxide, the products are water and 
m£ote ; when the proportion of hydrogen is small, nitric 
acid is also formed f . 

Sulphuretedy phosphureted, and carbureted hydrogen 
gasy likewise burn when mixed with nitrous oxide, and 
exposed to a strong red heat. The products difler ac- 
cording to the proportions of the gases mixed. 

7. Neither azote nor muriatic acid ap[jear to have 
any marked action on tiiis gaseous oxid^4 

S. On some of the metals it acts with great energy 
at high temperaturrs* Thus iron wire bums in it witll 
the same brilliancy ?s in oxygen gas, though the coa« 
bustion lasts but a rery short time. The iron is Con- 
verted into bt -ck oxide ; part of the nitrous oxide is de^ 
composed, iis azote is evolved, while its oxygen com- 
bines with the iron t* Zinc also may be oxidized in 
this gas {. Its e£R:ct upon the other metals has not been 
tried. 

g. Oacide of azote is capable of combining with alka- 
lies, and forming saltsof artry peculiar nature ^ for the 
discovery of which we are indebted to the sagacity of 
Mr Davy. No combination takes place when the alks- 



I IM. ii. 86. 



f Prieiclcy, ii. 83. and Oav^^ p. sli; 
5Dary,p;|i7; 



I |a nitrons oxide in the gaseous stste. 
o contact with tfaem at the instant of 

formuion, it combines tvilh them very readily. As 
sc combiDatHios have not yet received a name, we 
\.f call tliem azolilti till some belter appellation be 
mght of. 

Axorite of potash may be forned by the rollowiog 
Ttxn : Niiraus gas (a substance which will be descn- 
d imoied lately), by confining in it crystallized sul- 
hc of pottsht, is gradually deprived of a portion of 

oxygen, and converted into nitrons oxide. If very 
ely pulverised sulphite of potash, mixed with potash, 

exposed for a great length of lime in a stitBcient 
ftltlity of nitrous gas, ii is changed almost complcte- 
into sulphate of potash, while the oxide of azote, as it 

evolved, combines with the puro potash. Conse. 
cntlythe salt is converted into amixture of sulphate 

potash and azotiie of potash. The sulphate may be ; 
panted by solution, evaporation, and crystallization 

a low temperature. 

Azotits of potash is obtained in irregular crystals. 
it ooinposcd of about three parts of alkali and one 
iR of nitrous oxide. It is soluble in water. Its taste 
ctmlic, and it bas a peculiar pungency. It ci 
geMble blues into greeu. Pulverised charcoal, ' 



• Mi Danjr ha pr^po^J lu all them a./r ^i, ,- but ihtt name ii n. 
ituMnblc, Dot oulf bccjiiM ii i> tautnfy to ihu iJiom of the Engtigh 
euagc, but ticciuK it a incuniuUQC with the rulea hid down for 
nung chemical cenni. 

\ Potub combined wiili lulpbtuoui Kid. Thii mIi hu a Mrong \ft- 
J lor osfftn. k ■bwrbi ii fnan aitiout gu. mdi* convaced iotp 
•iati tfftaib. Hence the tlunge of utroui gii lo nimoi oiide. 



ed with it, and inflamed, bnmi with slight sciniUlattoaM 
I When projected into zinc in fusion, a slight inllam 
tion lakes place. All acids, even carbonic, seem capa* 
ble of expelling the nitrous oxide from the potash V 
The other properiies of this salt have not been cxs* 
mined. 

Azotite of soda may be formed in the same iiuoDer, 
and seems to agree nearly in its properties with azotitt 
of potash. The niuous oxide is disengaged from it bj^ 
a heat of between 400' and 300°. Its taste is more 
acrid than that of aioiitc of potash, and it seems tocoD- 
tain less oxide of azote f . 

Mr Davy did not succeed in combining nitrou* oxid* 
with ammonia and earths i but he has rendered it pro* 
bablc that these azotitea may be formed. 

10. From the history of the properties of nitrons ox* 
ide gas just detailed, it is obvious that it is a supportei 
of combustion, and therefore that it contains oxygen n 
the same sUle as it exists in other supporters. Thatltl 
other component pari is azoie, cannot be doubted, if we 
consider that either azole or nitric acid is constantlj 
evolved when nitrous oxide is decomposed. The txpt-t 
rimentsof Mr Davy leave no doubt that thtse two sub- 
stances are its only constituents. This philosopher found 
that 39 measures of nitrous oxide gas arc capable of s>*. 
lurating 40 measures of hydrogen, and thai after com- 
bustion liie residue consists of 41 measures of azotic ga**~ 
But 40 measures of hydrogen were found to requii 
20-8 measures of oxygen |. From this it foUowi, tht 



t Ibi4 f. 191. 



r 



OF AZOTE. 

if the component part of nitrous oxide were merely 
mixed together, the bulk of ihem would occupy a third 
more room than when combiaed ; for 40 meaiurei of 
DitrouB oxide would be resolved into 20*8 
ozjgen gas and 40 measures of azotic gas * : But 20^8 
cubic inches of oxygen gas weigh about seven graintj 
tnd 40 of azotic gas about 12 grains. Hence it follows, 
thai nitrous oxide is composed of seven parts by weight 
«f (urfgen, and 18 of azote, or nearly 

6S azote, 

37 oxygen, 



This statement coincides very nearly with the specific 
gravity of nitrous oxide. Thirty-nine cubic inches of 
nitrous gas, if the composition here given were precise, 
ought to weigh 19-38 grains, fn reality ihey weigh 
lO'flg grains. The component parts of this gas, as ob- 
tained by the Dutch chemists, differ very little from the 
resull of Mr Davy's expcriaienis. 

Much is still wanting to render the history of this 
lingular substance complete. Mr Davy has laid open a 
very interesting field of investigation, which promises, 
if pursued far enough, to throw much light upon the 
nature of corobusiion : an operation more intimately 
coooecied with azoie and its compounds than is at pre- 
sent supposed. 




Bieuure,bccs>uc the gaiei ■ 



(fiol^btoliicclf pore 



1 



162 



gxiX>£ft 



Book IT. 
BWiiion K. 



11. Nitric Oxide. 



Histoiy. 



Frepara* 
tion. 



IVopcrtiM. 



Nitric oxide, usually deoominated nitrous gas, way 
obtained accidentally by Dr Halet ; bat its oature aod 
properties were investigated by Priestley, in one of the 
first excursions made by that illustrious philosopher 
into the then unbeaten tracts of pneumatic chemistiy. 
As the phenomena exhibited by this oxide are inti- 
mately connected with the most important investigi- 
tions in chemistry, its properties were examined with 
great care, and occupied the attention of almost every 
chemist of eminence. 

1. It may be obtained by the following prooesi: 
Put copper or mercury into a glass retort, and pour 
over it somewhat diluted nitric acid. The metal is 
rapidly dissolved with a strong effervescence, and a 
great quantity of gas issues from the mouth of the re- 
tort, which may beoreceived in glass jars. This gas it 
nitrous gas, 

2. When pure it is Invisible like common air, of 
which it possesses the mechanical properties. Its spe- 
cific gravity is 1*094, that of air being 1*000, accord- 
ing to Davy *. Nitrous gas, then, is to common air 
nearly as 34 to 81. One hundred cubic inches of it, 
at the temperature of 60^, barometer 30 inches, weigh 
:s3*i)i:3 grains. 

Nitrous gas is exceedingly noxious to animals, pro- 
ducing instant suffocation whenever they attempt to 
breathe it. 



♦ Raeareletf p. 6. 



OF AZOtE. 

i greater number of combuslible bodies refuse to 
A taper, for instance, Js exiingtit&lieu ihc : 
'ntotneiit it is plunge * into nitrous gas ; the same thing ' 
bap pent to sulphur, even though previously burning 
^Tviiha white flime. It is capuble, however, of support- 
ing the combustion of several bodies, as has been ascer- 
tained by the expcriuieiUi of Priestley and Davy. 
When Ilomberg's pyiopiioru^ " is inicoduced into iii- 
(fouj gw, ii takes fiie sponlaneoosly, jusi as it docs in 
common air. Phosphorus, too, when introduced into 
this gas in a state of inflammation, bums mill as much 
splendour as in oxygen gas f . 

4. When nitrous gas and common airare mixed to- ; 
getber, llie mislure instantly as^ulI)es a yellow colour, ' 
heat is evolved, and the bulk o! itie two gases dimi- 
nishes considerably j slowly, if the expenmeni be made 
mtr mcfcury j but rapidly, if it be made over water. 
When the diminution has reaelied its maximum, the 
mixture becomes perfectly transparent. The yellow 
colour is owing to a ijuaniity of nitrous acid nhch ii 
formed, and the diminution of bulk to ihe gradual ab- 
sorption and condensation of this acid. What remains 
■fier this absoipiion is only azotic ^as. The cause of 
(his rematkable phenom«i<on isobvious. The nitrous 
■^t combines with the oxygen of the air* and lorms 
nitrous acid which is condensed ) while the azote of 
the air remains bcliind in the foriD of a gas. Henc« 
witti equal quaiiiiiics of nitrous gas and air the diinmu- 
tton d{ bnlic is always proportional to the quauuty of 



'PC'"! 



' Thii Hibwuice iriU bs i 
■fil ii chuco*! aud mlphur. 



bed heicafier. llic eombtutiblr pitt 



OXIDZS 



A«ti<n of 



n the a 



Hence i 



informs u 



lubstsncc 



■4 



oxygen preMiil 
proportion of th 
&3rae phenoniuion lakes place when oxygta gas ttnd nJ- 
trgus gas arc mixtrij ; but the condcnsaiion U much 
more con&iderabl*. Indeed it would be complete, pro- 
vided ihe two gases wece perfectly pure, and mixed ii 
the proper proportion' 

From the cxpetiments of Mr Dalton wc learn ibal 
nitrous gas combines with two different proponioni 
oxygen gas. 21 measures of oxygen gas uniting 
cither with Sfi measures of nitrous gas, oi with 7S nics> 
aures*. 

When electric sparks are made m pass ttut>ngh ni- , 
ttous gas, it is decomposed and coavcrtcd into i 
uid and azotie gat f. 

5- Nitrous gas is readily absorbed by water, 
an experiment of Mr Davy, it appears that 100 < 
iJDcbes of water at the common temperature, and p 
viouUy freed from air, absorb ii;8 cubic inches of a 
Irons gas, or nearly one-tenth, as Dr Priestley had i 
ceriained ; but the experiments of Dr Henry do i 
accord with this estimate. Water, by bis Iriali, at l 
temperature of €0°, absoibs only five ^if- »Rt. of tl 
bulk of this gas %. Thii solution has tu> particular li 
and does not redden blue vegetable colours, 
is expelled again by boiling ihcwaterj; it scpu 
likewise when the water is froi!.en ||. 

6. Nitrous gas is decomposed by phosphorus m 
charcoal at a very high temperature, and probtUj ■ 



\ttiL M^. aid. 3St. 

t nu.Tr-H.. 1803, p. .74. 
B Piieitlcy.ii. 407. 



OT AZOTT. 16S 



B lliir'ailphur. These substances are convened into adds W"p> '• 
hj combining with the oxygen of the gas while its azote 
it evolved. 

Hjdrogen gas mixed with it acquires the properly of 
tmnung with a green flame. A mixture nf these two 
gBsei does not take fire when electric sparks are made 
to pass through it ; but according to Fourcroj, it de- 
tonates when made to pass through a red Hot porcelain 
tube ; water is formed, and azotic gas is evolved *. 

7. Nitrous gas has no action whatever on azotic gas, Incombn*- 
ercn when assisted by heat. Neither does it act on " "" 
muriatic acid. 

8. Several of the metals have the property of dccom- Andioeuli. 
pOBtag it, especially when assisted by heat. Thisislhe 

case particularly with iron. Dr Priestley confined a 
portion of nitrous gas for some time in contact with a 
oomber of iron nails ; the gas was converted into oxide 
of azote^ in consequence, doubtless, of the iron ab- 
stracting part of its oxygenf . It was in this manner 
that nitrous oxide was discovered by that philosopher. 
When the iron is heated to redness by means of a bnin- 
ing.glast, the decomposition is complete, the whole of 
tfae oxygen is abstracted from the nitrous gas, and oaly 
azotic gas remains behind t- 

9. Dr Pricsdey ascertained that nitrous gas is ab« Absorbed 
soibed by the green sulphate of iron; a property which ^'/.'"'p'"'' 
is employed successfully to ascertain its purity. All 

that is tieccssary is, to expose a given portion of nitrous 
\ n close vessel to the action of the green sulphate ; . 



I 



tW OXIDES 

f^y n* the quantity of ?as which remains unabsorbed gxvet 
i y ■■' the proportion of foreign bodies with which it is mixed. 
Mr Davy has proved^ that all the sahs containiDg the 
black oxide of iron possess the same property, and that 
they all absorb nitrous gas unaltered* The greatest 
part of it may even be expelled again by the applica- 
tion of heat. Several otlier metallic salu possess th^ 
same properties *. 
Converted JO. The following bodies have the property of coil> 

inrotiitruuf • • • 'j • • • « 

^^^ verting nunc oxide into nitrous oxide. 

Alkaline sulphites, 

Hydrogureted sulphuretSf 

Muriate of tin, 

3ulphureted hydrogen gas. 

Iron or zinc filings moistened with waten 

To produce this eflfcct, nothing more is necessary 
than to put these substances into jars filled with nitric 
oxide gas, and allow tlitm toren>ain for a w*eekor two. 
The substances gradually combine with a portion of 
oxygen, and ape converted into oxides or salts f. 

11. Nitrous jgas is absorbed by alkaline solutionis 
but it does not appear frc m the experiments hitherto 
made, that it is capable, like oxide of azote, of com- 
bining with alkalies and earths, and forming salts. 
CompMi- 12. The conversion of nitric oxide gas into nitric acid* 

twn, Y)j combining it with oxygen, is a demonstration that it 



♦ D*vy, p. ! 79. 

f VricstUy and Davy./.-i/iw.—Durinj the action of the two last Ihi» 
dips pp nUrous gas, ammonia is likewise lormeJ* 



»• 



ctiirtains azote as a constituent part ; and the property 
which several bodies have of absorbing oxygen from 
il,and convening it into nitrous oxide gas, is a demon, 
slrattoa that oxygen is the only other ingredient -which 
it contains. But it is by no means easy to ascertain 
the proportion of these two conelimenis. Mr Lavoi^ 
sier, from a set of experiments mnde at an cafly period, 
and in a manner not susceptible of mttcli accuracy, es- 
timated their proportions ai about oS oxygen and 32 
miMt. But ibis eslitnaie is irreconcilcable with the e;^- 
penments of other philosophers. Tlie proportions ob- 
tiined by Mr Davy deserve much more confidence, as 



By 



his method u*as susceptible of greater accuracy. 
means of a faurning-gla^s he exposed to the actit 
ibc sun's rays a small portion of prepared charcoal, 
placed in a measured quantity ofnitiic oxide gas stand- 
ing over mercury. The weight of the charcoal did 
not exceed a quarter of a grain, and the gas amounted 
to 16 very small measures. A^er the process was 
finished, the bulk of the gas was increased about^ths 
of a measure. The whole of the nitric oxide was de. 
composed. Potash ley rapidly absorbed ihc whole of 
ibc gas except eight measures, which were pure azote. 
But the gas originally was found by cxperiinent to con- 
tain 0*6 of a measure of azote. Tlierefore 15'4 
measures of nitric oxide, when decomposed by char- 
coal, are convened into 16'15 measures; T4 of which 
are azote, and 6-75 carbonic acid. But J5'4 measures 
of nitric oside weigh 5'2 grains, and "-4 measures of 
azote weigh 2'2 grains. Hence it follows thai 5-2 grains 
of nitric oxide contain 2'2 of azote ; the remaining S 
grains must be oxygen. This gives us nitric oxide 
composed of 2*2 azote and 3 oxygen, or of 5T7 oxy- 



sr* 



16S 



OXIOIf. 



Bookir. 
PiviiioD ir. 



gen and 42*3 of azote. The carbonic actd prodoeed 
weighed 4'1 grains, and contained 1*15 grains of char- 
coal combined with 2*95 grains of oxygen, which it had 
absorbed from the nitric oxide. This gives ot 5*2 gratm 
of nitric oidde, composed of 2*05 oxygen and 2*25 
axote ; or 100 parts contain 57 oxygen and 45 azotCi 
which diflPers very little from the last estimate *• We 
may consider the last numbers as the nearest approxi- 
mations to the composition of nitric o^de. 

The proportion of oxygen contained in the com- 
pounds of azote, according to these results^ may there- 
fore be stated thus : 



Aiote. 


Oxygen. 




100 


58*7 
136 


Nitrous oxide 


100 


Nitric oxide 


100 


236 


Nitric acid 



Hence it follows that 



NittoiM 
.\sote. Oxygen, oxide. 

1*00 + 0*58 = 1*58 Oxygen. 

1-58 4- 0*78: 



HHk 



Nitric 
Glide. 
2*36 Oiyf». 

2*36 + 1*00 S $*S« 



*DtTy,p. IS9. 



OF ACIDS. 



IhC word Acid, originally synonymous with Soon, 
and applied only to bodies disiinguished by '.list lasic, 
his been gradually extended in irs signiticatio by che- 
uiMa, and now comprehenda under it alt jubsianccs 
possessed of ibe following properties : 

I. Wh«n applied lo the tongue, iheyeicite that sen. p,™^—!- 
Mtioti which is called sour or acid. 
' 2. They change the blut- colours of vegetables to x 
l*d. The vegetable blues employed for thi» purpose 
br« -generally infusion of litmus and syrup of violets or, 
isf raddishes, which have obtained the name of rtagentt 
or ttUi. If these colours liave been previously con. 
Tcrted to a grttn by alkalies, the acids restore them 

9. They unite with water in almost any proportion. 

4. They combine with all the alkalies, and most of 

the metallic oxides and earths, and form with them 

those compoimds which are called lalti. 

' It must be remarked, however, that every acid does 



110 PRIMARY COMPOUKOS. 

Boc^ If. not possess all these properties ; but all of them possets 
-_ a sufScient number of them to distinguish them from 

other substances. And this is the only purpose which 
artificial definition is meant to answer. 

The acids are by far the most important class of bo- 
dies in chemistry. It was by their means indeed, by 
studying their properties, and by employing them as 
instruments in the examination of other bodies, thst 
men of science laid the foundation of chemistry, and 
brought it to that state in which we find it at present. 
The nature and composition of acids, therefore, be* 
came a very important point of discussion, and occn* 
pied the attention of the most eminent cultivators of 
the science. 
Opiuion Paracelsus believed that there was only one acid prio« 

cooceraing ^jpj^ jji nature which communicated taste and solubility 
principle. to the bodies in which it was combined. Beccher em- 
braced the same opinion ; and added to it, that this acid 
principle was a compound of earth and water, which he 
considered, as two elements. Stahl adopted the theory 
of Beccher, and endeavoured to prove that his acid prin-' 
ciple is sulphuric acid -, of which, according to him, all 
the other acids are mere compounds. But his proote 
were only conjectures or vague experiments, from wbiclm 
nothing could be deduced. Nevertheless, his opinion, 
like every other which he advanced in chemistry, con* 
tinned to have supporters for a long time, and was even 
countenanced by Macquer. At last its defects began to 
be perceived : Bergman and Scheele declared openly 
against it^ and their discoveries, together with those 
of Lavoisier, demonstrated the falsehood of both parts 
ol the theory, \>j showing that sulphuric acid does sot 



ACIDS. Ill 

^OM in the other acids, and ihat it w not composed of Chip- n.^ 

fUcv and earth, but of sulphur and oxygen. 
Tile oi>inion, however, ihai acidity is owing to some 
i&ciplc common to all ihe sails, was not abandoned. 

V^allcnus, Mryer, and Sage, had advanced diBerent 

tlieoHes m succession about the nature of this prin- 
Cplc i but as they were founded rather on conjecture 
iai analogy than direct proof, they obtained but few 
idtocaies. Al last Mr Lavoisier, by a number of in- 
gcmoat Slid accuiaie experimenis, proved that several 

combustible subsiBiices "hen united with oxvcen form Suppowd 

/* atyitm. 

acids i (hat a great number of acids contain oxygen; 
and that when this principle is scparaied from them, 
ihejr lose their acid properties. He concludi^d, there- 
fote, that the acidifying principle is oxygen, and that 
(cida an nothing else but combustible substances corn- 
lined with oxygen, and difTeiing froin one another ac- 
Cotding to the nature of the combubiible base. 

Iliis condusion, as far as regards the greater ntim- 
kr of acids, is ccnainly true. All Ihe simpleporobus- 
iblei, txcipl hyd'ogen, are ccnvcriible into acids; and 
\e acids are ct>m[joscd of oxygen and the comfaus. 
t>lc body conibined. This is the case also with four 
^ the metals. It n<u5tnot, however, be admiilcd with. 
M< some limitation. 

When it is -^aid that oxygen is the acidifying prin- 
^ple, it is not meant surely to afllrm that oxygen pos- 
pCLUts the piopciiies of an acid, wliich would be con- 
y to tiuih i all that can be meant is, that it enters 
^ a component pan into acids, or that acids contain ic 
aucs^cniial ingredient. 

S. But, even in this ^en^e, the asMrtion cannot be td> 
iucd ssdcmousiratcd. For it bat not yet been shown 




172 PRIMAUr COMPOVVDS. 

» Book H. that oxjgen is an essential ingredient in aU adds. MiA 
'^'*'" ' riatic acid, for example, has not jet been proved to 
contain oxygen, and the same obserration applies 
to some other substances oniversallj admitted amoag 
acids. 

3» When it is said that oxjgen is the acidifying prio> 
ciple, it cannot be meant surelj to affirm that the cooh 
bination of oxjgen with bodies produces in all cases sa 
acid, or that whenever a bodj is combined with oxygco, 
the product is an acid ; for the contrarj is known to 
tvcTj chemist. Hydrogen, for instance, when oombi* 
ned with oxjgen, forms not an acid, but water, and die 
greater number of metallic bodies form onlj ozidet. 

The recent discoveries of Mr Davj render thii^ if 
possible, still more obvious. For we now know tbit 
the alkalies contain oxjgen, and that thej are aa nradi 
indebted to that principle for their alkaline qnalitieiii 
the acids are to it for their acid qualities. 

AU that can be meant, then^ when it is said that oxj. 
gen is the acidifying principle, is merely that it existi 
as a component part in the greater number of acids; 
and that manj acids are formed bj combustion, or bj 
some equivalent process. The truth is, that the dm 
of acids is altogether arbitrar j ; formed when the great- 
er number of the bodies arranged under it were un- 
known, and before an j preci&e notion of what ought 
to constitute the characteristic marks of an a^id bad 
been thought of. New bodies, when thej were disco- 
vered, if they possessed any properties analagons to the 
known acids, were referred witliout scruple to the same 
class, how much soever they differed from them in other 
particulars. Hence we find, under the head of acids, 
bodies which have scarcely a single property in com- 



r* 



,S»on except that of combmiag with alkalies and eaiths. 
Whst lubitances, for instance, can be marc dissimilar 
than aujpliuric, priissic, and uric acids ? Hence ilie dif- 
ficullj of assigning ihe genera) characters of the class 
of scids, aod ibe disputes which have ariaen about the 
pfoprieiy of classing certain bodies among acids. II 
wc lay it down as aii axiom ibat oxygen is tbe acidtfy- 
iog principle, we must either include among acids a 
givat nnoiber of bodies nhich have not the umailcst re- 
xemblance to those substances which are at present 
Hckoned acids, or exclude from the class several bodies 
whicti have the properties of acids in periectioti. Tbe 
daas of >cids being perfectly arbitrary, there cannot be 
such a thing as »a acidifying pcinciple in the most ex- 
iravvc sense of liie word. 

ficTthpikihailaielyproposedadefioition of acid, which, 
though not unexceptionable, gives us, 1 think, more 
precitc notions of this class of bodies than those former- 
ly entertained. Acids, according to him, are bodies 
capable of combining with alkalies, and of neutralizing 
them, while, at the same time, they lose their acidity *. 
According to this notion, the capacity of neuiralixing 
each other constitutes the essential characters both of 
adds and alkalies; and that acid which is capable of 
neutralizing the greatest quantity of alkali possesses the 
character of acidity in greatest perfection. Were this 
ddinition admitted, several bodies at present arranged 
nmong acids would be excluded from that class. Tbe 
greatest obiection to it is the existence of some substan- 
ces which occasionally act the part both of acids and 



• Swfj.i Ctimigtr, i. «9. 



a ^:j <tt. 



1T4 PRIMARY COMPOUNDS. 

ly*^ ' u. alkalies, and ought therefore to belong to both tets rf 
< i-y substances. But perhaps these bodies (the metallic ox« 

ides) do not rigidly neutralize alkalies, and therefore 
approach more closely to that class. Besides, we csa 
scarcely expect perfect precision in our arbitrary classi- 
fications. 
£j]||^ ^ ^* ^^ ^^^ ^ ^^^ comprehends under it a consi- 
derable number of bodies, the subdivision of them un- 
der subordinate heads will be'attendcd with consider* 
able advantage. Now, all the acids^ like the oadei^ 
are either prodMcts of combustion, or n^fortert of coa- 
busdon, or comimsiiiU* And upon ezaminatioD, it most 
appear evident tfaat%each of these classes posaesaes such 
characters of distinction as to warrant their being 
sidered separately. I shall therefore divide the 
into the three following classes : 1% Products $ 8. Sap* 
porters $ 3. Combustibles. The acids belongiagtolbt 
two first classes have only a single base j but those be* 
longing to the third have usually two or more baaei^ 
and are sometimes destitute of oxygen. 



ACIDS* 




CLASS I. 



OF ACID PRODUCTS* 



All the acids which belong to this diss possess the 
Allowing properties. 

1. They may be fornied by combostioo. Of course Pwp*"**' 
their base is a combustible substance. 

2» They are incombustible* 

3. They cannot be decomposed by the action of the 
most violent heat which- can be applied *• 

4. They are all decomposible by the joint action of 
a combustible body and caloric. 

5. Oxygen is an essential ingredient in all of them. 
To them, therefore, the theory of Lavoisier applies with 
precision. 

Some of the simple combustibles are capable of corn* 
bining with two doses of oxygep, and forming acids 
mth each. When that happens, the acid containing 
^he minimum of oxygen is distinguished by the termi« 



* To this propeity there are some exceptions. It tppeart (t&ok tfce 
tate ezpcrimeDU of Gay-LuMic that sulphuric acid it drcomponbk bj 
beat. Mem^^Arnteil^u %t$. 



i7fl 



ACIB PRODUCTS. 



DiYiiion H. 



Mtmetind 

coniposi- 

cigo. 



nation ous ; that v^hich contains the mazimam, by the 
termination iV. Thus the acid of sulphur, with a mi- 
nimum of oxygen, is sulphurous acid ; the acid of sal- 
phur, with a maximum of oxygen, is ^Iphuric acid. 
But it must be remarked, that this mode of distinguish, 
ing the doses of oxygen in acids is restricted to ibe 
first class of acids, and does not apply to the other two 
classes, except in one instance. ^ 

The acid products at present known are only five is 
number : but I am obliged to add to them, £rom analo- 
gy, two other acids, which have not hitherto been de» 
compounded, but whose properties bear a mndi dour 
resemblance to the products than to any of the odKr 
classes of acids. The following Table cxbitHtt tk& 
names and tonstitnent parti of these adds as £Mr as Ih^ 
have been ascertained* 



Nwnct. 

• 


Bmci* 


Proportion of 
oiy gen co^feo bite. 


Sulphuric 
Sulphurous 


Sulphur 


136-5 
88*d 


Phosphoric 
Phosphorons 


Phosphorus 


114*7 


C ;rbonic 


Carbon 


257 


Fluoric 
Boracic 


Unknown 





From this Tabic it is obvious that the acids belonging 
to this class are named from their bases. The two last, 
tjbe component parts of wl:ic:i are linknown, are deno- 
jminat^d from the substances ivhich contain them siofi 

abundantlv. 



ACID PRODUCT?. 



OF 3VLrHURIC ACID. 

Xboooh the ancients were acquainted with some of 
tbc compounds into which sulphuric acid enters, aium, 
tot iaiunce, and grtea vitriol, they appear lo have been 
.ignorant of the acid itself. It is first mentioned in the 
Worki of Basil Valeoiine, which were published about 
llie cad of the I5lh century. It was for a long lime 
tbcained by distilling ^^fjt vitriol, » ta\l composed of 
>ju]phuric acid and black onde of iron ; hence it wai) 
piUcd oil «/ vitriol, and afterwards vitriofic acid. An- 
;ttheT method of obtaining it was by burning sulphur 
iBider I glass bell ; hence it was called also oleum tul- 
^btms frr eamfanatn. The French chemists, in 11S7, 
Iwben they formed the new chemical nomenclature, gaVe 
it the name of ndpburie acid. 

* 1. At present il is generally procured by burning a Prepnia- 
tuxlUTC of sulphur and nitre iu chambers lined with '""■ 
Jead. The theory of this process is still somewUal ob- 
jcnre. When sulphur is burnt in the open air or in ox- 
l^en gas, however high the temperature, only sulpbu- 
toiu acid is produced, and no appreciable quaniitj of 
knlphuiic add. If the sulphur be mixed with black 
pxidc of manganese or any metallic oxide which readily 
:s with its oxygen, the combustion is more brilliant, 
still sulphurous acid only is produced. No other 



ACID PRODUCTS. 

mcihod is known of producing sulphuric add by i 
. combusiion of sulphur, «xccpiing mixing it with nitn 
of potash. Now the ^Acuity is to explain ibc pi 
which the nitre acti. The quantity used varies homt 
fifth 10 a tenth of the sulphur burnt ; ind according IB 
(be experimenls of Chaptai, the best proportion ut 
Kvenih •, Now the whole oxygen contained in tU| 
portion of nitre does not exceed the seventh pan if lb 
bxygen necessary to convert the sulphur into sttplmi^ 
acid. It is obvious, therefore, that the necessity tt At 
nitre does not arise from its supplying the mfuak 
quantity ofoxygcu. The most probable explaaitid 
has been furnished by Clement and Desormes. Ac- 
cording to them, the nitric acid in the nitre is deco» 
posed by l!ie combustion, deprived of n portion of in 
oxygen, and emitted in the state of aitrous gas, wluls 
the sulphur is converted into sulphurous acid gas, v 
flies off mixed with (he aitrous ga<>. The nitrous gttlb- 
sorbs oxygen from the air of the apartment, and it i 
verted into nitric acid, which immediate-Iy gives outili 
oxygen to the sulphurous acid and converts it into inli 
phuiic acid. The nitrous gas is thus formed a sectfld 
time ; it absorbs oxygun a second time, and gives itl> 
way as before ; and this process is repeated till tfai 
tvhole sulpliurous acid is conveited into sulptmtii 
acidt. 

The sulphuric acid, when first formed, is vefy wei]^ 
being diluted with the water necessary for C0Ddeiuill| 
it ; but it is made stronger by distilling off a poitioa 
of this tvaier. By this process it is made quite t 



t Am. (fr Cf ». III. jif. 




«fU; butitauUcontaioialittlelcad, which itdissolved . ^g- '/f. 
riB the vessels in which it was manufactured, and a lit- 
poUsb, which it acquired from the nitre employed in 
Iroiag the sulphur. To obtain it in a state of complete 
irit;^, the sulphurit; acid of commerce must be distilled. 
[lis is easily done by putting it into a small retort with 
long beak. The bottom of tbc retort is placed up- 
I a 6re of charcoal, and flxrd steady by means of an 
OD nag; while its beak is plunged halfway into a 
whose moulh it fits nearly, but not exactly. 

Die tdd soon boils, and is gradually condensed in the 
iceirer* Too great a quantity should not be distilled 
t once, otherwise the retort generally breaks in conse- 
of the violent agitation into which the boiling 
a a thrown. 

3. Sulphuric acid is a liquid somewhatof an oily coo- PicFcniu. 
Rence, transparent and colourless as water, without 

uynncll, and of a very strong acid laste. When ap- 

^t<d to animal or vegetable substances, it very soon 

kitroys their texture. 
It always contains a quantity of water; part of which, 
wever, may be driven oif by the application of a mo- 
rale beat. This is called concentrating the acid, 

P^en as much concentrated as possible, its specific gra- 

\\y is said to be 2'000 ; but it can seldom be obtained 
ijCT than 1-85. 

4t changes all vegetable blues to a led except indigo. 

pcording to Erxleben, it boils at 546° ; according to 
rgman, at 540" *. 

Whca exposed to a suflScient degree of cold, it cry*.* 



180 ACID PRODUCTS. 

Book IK tallizes or freezes ; and after this has once taKen placr^ 
It freezes again bj the application of a much inferior 
cold *. Morveau froze it at -*4* ; it assnmed the apt 
pearance of frozen snow. After the proceaa bq^m, it 
vrent on in a cold not nearly so intense. The add mdu 
ed slowly at 27*5*^; but it froze again at the same teiB-> 
perature, and took five days to melt in the temperatme 
of 43*^ t* Chaptaly who roanufaeturec) this add^ oaoe 
observed a large glass vessel full of it crystallitAd at the 
temperature of 4S^. These crystals were in gmpi^ 
and consisted of flat hexahedral prisms, termiiwtad by 
a six-sided pyramid. They felt hotter than the sin 
rounding bodies^ and melted on being handled )» Chap* 
tal has observed, that sulphuric acid, in order to crji- 
tallize,. must not be too concentrated. This obaervatioi 
has been extended a good deal further by Mr Ketr. ft 
found that sulphuric acid, of the specific gravity of 
1*780, froze at 45^ ; but if it was either much neitor 
much less concentrated, it required a much greater eoU 
for congelation ||. When as concentrated aapoasiUeyP 
find that it may be cooled down in thermometer tnbei 
to the temperature of —30^ before it congealt f • 
Action of 3^. Sulphiiric acid has a very strong attractioa ftr 

water. Neuman found, that when txpowtd to the at- 
mosphere it attracted 0*25 times hs own weight. ICr 
Gould found, that 180 grains of acid, when esposed to 
the atmosphere, attracted 68 grains of water the irst 
day, 58 the second, 39 the third, 2^ the fbiutliy 18 the 



wtter. 



* The freezing point wai asceruined hj the Dae d'Afea in 1776. Sm- 
Macqaer*! Dlethnary. 

\ Emcycl. MeiM, Cbim, i. 376. { Jmr. 4t Pbjt. zui. 47J. 

r HH. Trans. Ixivii. Part iL ^ Sec VoL I. p. jlj* 



Audi, atad It last only 5, 4, s, 4, 3, &c. The sath day , 
the augmentation w»only half » ^rsin ". Tbe aflinity 
Iherefore between sulphuric acid and jwater, as is the 
case in general with other substances, becomes weaker 
the Bearer it approaches to jaluration. He does not 
specify ifae specific gravity of his acid ; but as it only 
attracted 3*106 limes its own weight, it could not have 
beea very concentrated. 

The affinity between sulphuric acid and water be- 
Gomei itill more striking when these bodies are mixed 
together. If four parts of sulphuric acid and one part 
•( ice, both at the tecnperature of 32", be miKcd toge- 
ther, ibc ice melts inslantly, and the temperature of the 
mixture becomes 212°. On the other hand, if four 
pans of ice and one part of acid, at 3^", be mixed toge- 
ther, the temperature sinks to about — 4° • The cause 
of this change of temperature has been already explain- — 
ed. When four parts of acid and one part of water 
ate mixed together, the temperature of the mixture 
nses to about :toa° f. The density of this compound of 
acid and water is much greater than the mean. Heat is 
also evidved when other proportions of acid and water 
aretnixed together, though not in so great quantity. 
l^voisier and De la Place found, that when 2-flZSlbs. 
ttoy of sulphuric acid, of tlie specific gravity fSiOSS, 
vrcTC mixed with I'deglb. troy of water, as much ca- 
joric was evolved as melted 4-1226 lbs. troy of ice, or 
«s much caloric as the acid and water would have given 
«ut had they been heated without mixture lo 155*9° }. 

We have no reason lo suppose that sulphuric acid, ai 



I Mtm. Ptr. f jgo 



i FouKrojr, ii. 65. 



ACID rRODUCTt. 

Book II. iiie deniiiiy of ij-ooo, is free from sll miztare of* 

' M -' so far from that, ve know for certain that i 
virloui " co'iii<lca'''e proportion i for when it is combtncil w 
tltniiii-i. other hodii-s (barytes, for injiince, or poiasti), C 
a considernblc qiinntily of walcr which remains h 
and doci not enter inio the combination. Now, ii 
possible lo determine bow much real acid i 
much w ater are covuained in a given quimity.d 
a given specific gravity ? Attempts wei 
*wer thi» important question by Hoinbcrj 
man, by Wenic), and by Wiegleb ; but ihc differene* 
between thrir detFrmtnations were too great to places^ 
confidence in their accuracy. The subject has latdjr 
been resumed, and prosecuted with much ioduUry n 
skill by Mr Kirwan, whose results may be considered 
ni approaching as nearly to perfect accuracy na the pre. 
sentEtaieof the science admits. His method wait 
follows : He dissolved 80 grains of potash in water,an 
saturated it exactly with sulphuric acid of a given spi 
cific gravity (we shall suppose of 2'00), and diluted it 
wit'i water till its specific gravity was 1"0I9. The 
whole weight amounted lo 3fl94 grains. Foriy>fi« 
grains of snlphaie of potash, dissolved in lOlT grainirf 
distilled water, have the same specific gravity at tbe 
same temperature) whence it follows, that (he propofw 
lion of Bah in each was equal. But in the last soluiioi 

^ the quantitjf of salt was -— - of the whole j tfaereicQ 



grains. Now of thts weight BO grains were alkali ; i' 
remainder, therefore, which nmoiints to "i3'S2 grail 
must be acid. But the quantity of tfcid cmplojccl n 



SHLTHUAIC. 

of this there weiefi'52 grains which did not 
iter into the combination, and wiiich muu have been 
ire water : ~9 paits of add, of the specilic gravity 3, 
berefoire, contain at least 0-52 parts of water ; and 
iseqnentij lOO parts of it concskiti S'l'5 parts of wa- 
it onlr remains now to consider how much water 
■IphUe of potash contains. Mr Kirwan thinks it 
iDtains none, because it loses no weight in any de- 
CD of heat below ignition; and even when exposed 
a red heat for half an hour it hardly loses a grain. 
Diis is certainly sufficient to prove, at lesst, that it 
lODUins very little water ; and consequently we may 
xntdude, with Mr Kirwan, that 100 parts of sul- 
phtuic acid, of the specific gravity S'OOO, are com- 
posed pretty nearly of 91'75 of pure acid end 8*25 of 
Irater. 

Since there is such a strong afiinity between sulphu- 
|ic acid and water, and since the density of the mixture 
is diflerenl from the mean density of the ingredients, it 
becomes a problem of the greatest importance to deler- 
bow much of the strongest sulphuric acid that can 
be psepared exists in any given quantity of sulphuric 
kdd of inferior specific gra,vity, and which consequently 
GODStsts of a determinate quautity of this -strong acid 
kiluted with water. 

This problem has been solved by Mr Kirwan *. He 
book sulphuric acid of the specific gravity 2000, which 
b tbc strongest that can be procured, for his standard, 
tbe point was to determine bow much of this standi 



ACID FItODUCTS. 



> given qnantity of acid of iaUtitif 



»o^". 2ri >ci<J existed 
■ I , ' (iciwtly. 

He concluded, from a number of experiments with 
sulphuric Rcid, of the specific gravities 1-8S40, I'S«89^ 
l'fl042, l'750o(for he could not procure an acid of ibt 
specific gravity 2-000 at the temperature of 60", il 
which his expcrioicnts were performed), thai wbea 
equal pans of statidard acid and water are mixed, tin 
density is increased by Vr'*" P"" "f 'he whole mixtun. 
Theti, by applying a formula given by Mr Poujet 
h« eilculftted, that the increase of deiisity, od mixii 



• Mr Pwjtt andcitook the MKntniiiun of Uic ipecific ihtUt rf 4r 
cnbul (nised iriih didErcac quuiciiiei nf mttr. He look far biiMi 

■irJ alcohol whoic ipccific grailty wu . 'Si«9. ai the Tcm]>enn>n 
f'S'7J°' ^' <'>^" fuimcd tea muturci ; Uic CrK conuifung niM Bt 
■urc> of ilinhal and one of wiicr, the lecoiid cigh: rnoMircs of ilml 
■nd twn of witer, and lo OH illl lite Ian cnntaincd oiiIt aie 'nwHnt 
Jtohot ind nice of w«er. He look cane diu ttch et [hett mcui 
iliMid contain cqukl bulki, which he aicetuiiicd by weight, •bKniw, 
itwt,aiiicaKuenf water wutoi nimureoCilcohnlu 11008199. Thi 
lOOOa grimi of wittr and Sijg of alcohol (orme'l a mitiure c( 
equal l)utk> of eaih. Troni the tpetifc gnvity of »ch of rhe« 
he dtxaitred hnw tnuih ihey had dlminiihiJ in bulk in eoinr<|Dcac(rf 
aijiursi bx ihc following method : 

Calling \ ihe ictl ipeciiic gra* itf of any of the milium ( B 
tiGc guilty foond tif catculatioo. iuppoiing nu Jiminiitlnn aflralki 
th« ninnhet' of auinirci conipoainjr the whoT< man ; » — > the : 
to which II i« reduced in cotwequeoec nf ntutnal peiwtrKiiiB — ii ii fl^' 
dent, linte (he iiKrnue of dentiiy doo not diminiih the weight tf ttf 



B r: n — > X A. Thertfon * = 



K~~B 




4yFetentquintities of standard add and water, 
,in the fellowmg Tabl£ : 



W»ter. 


raof 

Altohol. 


<hc whole V- 
lumc — I by 
ciptrimcDt 


Uy cakulitioo. 






o»H.9 


o-o 03 






0-0187 


<.r.i4 






oi)»41 


0>Ol« 






o-ei68 


o-ojjfi 






©■aiBS 








0'o:66 


ooi?6 






o«»o7 


o^a-i 






00113 


o-o.g* 






000+4 


a-c.o,, 



ll it evadenti from ttiii Tabic, liiat ihc dtounulica af the balk e/ lh« 
■dRoR Mlowt 1 regoUr progtcsdaii. It it urcilot when the meuufct 
if smtBT tad ilrobol wc cqiul, aut ilinuuiihei ii ii ai^proatha both end* 
«f tti« Brief. Mr Poujet iccouDU (oc ihii 1>r carKeiving ihe ilc^ial to 
be diHoWed in the witer, whiih ituiiii a part of it in in pwn, or abxiriM 
it. The qaintity almrbcd agght 10 be in the mio of thai of the MiWat 
■irf cf ibe tiody diiulieil, and each atctmrt of water will rel^n a ^uin- 
tily of akohol proptntioail lo the number of nicaiuro of alcohol in the 
oiiitutc. Tbiu in a miiiun formcil of nine meaiure! of alcohol aad one 
cf waiCTt the witer will conuin 1 quantity of alcohol <= f ; in OB* of 
eight [tieasum of alcobol and two of water, Itx wacet will coolMl a 
qoanlity of akobnl • S. Therefore the dinuDuilaa of bulk in each ni^ 
fwciiin 1 atia (ompounded of thcDiraiuretofslcoholand wmterwhich 
Ibnn It, in the TibU giren ibove. u 1 X 9. » X 8. 3 X 7. 4 X «. 
&;. AdJ in general, takitig ihc diminulioa of bulk when the mewrci 
vf both liqui-Ji -re cijnal (or a cotuiaat (juanoty. and calliog it t, calling 
AsBBmbcf oTmcatatciai the tiiunba of meuiuciof alcohol*, the in- 




I6d 



ACID rtOBUCTS. 



Book IT. 
DivMion II* 



Number of 
parts of 
water. 


Nirmberof 
parts of Stan- 
dard acid. 


Augineiit»- 
tioo of den- 
sky. 


6 


05 


0*0252 


10 


90 


0-0479 


15 


83 


0'067P 


20 


80 


0-0850 


25 


75 


0-09M 


30 


70 


0-1119 


95 


65 


0-1213 . 


40 


00 


0«1279 


45 


55 


0*1910 


50 


50 


0-1333 



(Trace of density or dimiputioii of bulk s / we AiU hftvt « : s : ; -X- 



4^ 



n— xX« and v^^X" *?-*'^> of (mtking ««-x) m4 c m— 4 « «*• 



The dtmiirottoii of bulk, cakuUced according to tiiit fonnttla^ makn 
the Ian tfoluttin of the Tibk in ^is note. Thcj corretpood very wcil 
with experiment, while the meaMiret of alcohol are nore than thote of 
wilter, hue not when the reircrie Is the case. This Mr Ponjet diinks it 
ow^ to this attnction which exists bctw;ren the ptrticlcf of WMer, and 
which, wb«n the water 4s considerable oompired with the akohol^icaiiu 
the unieii ^ the water with the aleohoL 



By th#; formula % 



A€n 



•4 fir* 



Hbe <]iMntity 0^ alcohol of the 



sundird may be determined in any mixture where the Aohol excecdi 

the Water. 
Let the number of measures, or the whole mass - « y 
The measures of alcohol • • • -J » it 
The diminution of bulk at equal measures • « •» r 
The diminution of bulk of a mixture containing r 



— 4^ 



.4**' 



measures of alcohol 

The specific gravity of water • ^ m 

Hie specific gravity of the alcohol - - « # 

The specific gravity of the unknown mixture - « jr 
Then since the incretse of density does not change the weight of tlK 



By adding these augmentations to the spt-ciiic gravity 
ni th<r above mixture, found by calculation, and taking 
the menn for the intermediate quantities, he drexv up a 
Imble of the quantity of acid of the density 2'00, con- 
^n(.d in a given weight of acid of inferior density, from 
a to l"4fi60. Sulphuric acid of this hst density con- 
tains just 0*5 of sulphuric acid of 2. The quantity 
contained in acids of inferior densities was 3>^certaiued 
£roai actual observation. He found by the fir^i pan of 
the liable, that lOO parts of aCid, of the tpecilic gravity 
J'8472, contained SS'3 parts <.iandard ; consequently 
400 grains of this acid contain 3S4 i;iains sianclnrd. He 
took six portions of this acid, each coulaining 400 grains, 
and added to them as much uaicr a^ made thcin con- 
tain respectively 48, 46, 44, 42, 40, 36 grains standard. 
The quantity of water to be added, in order to produce 
this etTecl, he found by the following method : Sup- 
pose K =:lhe quantity of water to be added to 400 parts 
of acid, that the mixture may contain 48 percent, of 
standard acid. Then 400 + .v : 354 : : iOn : 4B, and 
consequently x ^ 33T5. Afli^r finding the specific 
gravity of these, the half of each was t^en out, and as 



whole, I— xX'+i* 




iss 



ACID PRt)])UCTS. 



Book .11- 
DivUion II. 



fDOch water added ; and thus the specific gravttica cor* 
responding to 249 23, 22, 21, 20, 19, were found. 
Then six more portions, of 400 grmint each, wero taken, 
of the specific gravity I'-SSQS, and the proper qnamity 
of water added to make them contain 36, S4^ 32, 30, 
28, 26 per ceM. of standards Their specific grayitias 
were found, the half of them taken oat, and as much 
water added ; and thus the specific gravitj of It, 17, 
16, 15, 14, and 13 £tmnd. Care was taken, after orerjr 
addition of water, to allow, the ingrodiants sufficient 
time to unite. 

By multiplying the standard acid, aa escertatned in 
this Table, by 0*8026, he obtained the4[uantttjr of real 
add contained in sulphuric acid of diferent deoaitiea at 
the temperature of ^0*« This may be aecn in the fol- 
lowing Table *• 



Strength of 
ilphuric 



xooPtit^ 


Reil 


xoo Parts 


lUal 


8p. OfS^ty. 


Add. 


8p. OnTkf • 


Add. 


2*0000 


89*29 


1-8070 


75*60 


1*0859 


88-39 


1*7959 


75 — 


P971P 


87*50 


1*7849 


74*11 


1*9570 


86*61 


1-7738 


73*28 


1*9439 


85*71 


1*7629 


72*32 


1*9299 


84-82 


1-7519 


71-43 


1*9168 


83*93 


1-7416 


70-54+ 


1*9041 


83-04+ 


1-7312 


69*64 


1*8914 


82*14 


1-7208 


68*75 


l-i787 


81*25 


1'7104 


67-86 


1*8660 


80*36 


1-7000 


66-96 


1*8542 


79*46 


1*6890 


66*07 


1-8424 


78-57 


1-6800 


65*18 


1*8306 


77*68 


1-6701 


64*28 


1*8188 


76-79+ 


1-6602 


63-30 



t Nichol90ii*« Jo9f4l^ iii. tX3. 



■ 




SULFBUKIC. 




ll 




loePwii 


RmI 


■00 Pu-[l 


K«l 


.""FW^ 




5p. Graritj. 


Acid. 


Sp, GrxV,Vf. 


Airid. 




1-0503 


62-50 


1-2951 


31-25 




J-6401 


61-61 


1-2847 


30-35 






i'6312 


60-71 


1-2757 


29-46 


^^^J 




1-0211 


5962 


i-2Ci>a 


iiS-57-f 


^M 




1-C122 


59-93 


1-2589 


27-fi9 






1-602- 


58-03 


1-2510 


20-78 


^^^1 




1-5932 


5T14 


1-241 5 


25-89 


^H 




1-5S40 


56-25 


1-2320 


25-— 


■H 




1-5748 


55-36-1- 


1-2210 


24-10 






1-5056 


54-46 


1-2101 


23-21 


*^^1 




1-5564 


53-57 


1-2009 


22-32 


1 


1 


1-5473 


52-68 


1-1918 


21-43 


J 




1-5385 


51-78 


1-1B3.6 


20-53 + 


^^J 




1-5292 


30-ati 


i-n-t'i 


19-04 


^^^^H 




1-5202 


50-00 


1-1678 


18-75 


,^^^H 




1*5112 


40-11+ 


1-1614 


n-85 


^^^H 


1 


1-5022 


48-21 


1-1531 


10-90 


^^^^1 




1-4S33 


47-32 


1-1398 


16-07 


^^^H 




1-4844 


46-43 


1-1309 


15-18+ 


^^^1 


^u 


1-4755 


45-53 


1-120B 


14-28 


^^^^H 


^■B'l-400& 


44-04 


1-1129 


13-39 


^^^1 


^^H 1-4431 


43-75 


1-1011 


12-50 


^^^^1 


■f 


1-4189 


4Z-86-f 


1-0955 


11-60 


^^^H 




1-409B 
1-4010 












41-07 


1-0890 


10-71 


^^M 




1-3S75 


40-18 


1-0833 


9-80 


^^^H 




1-3708 


30-28 


1-0780 


8*93+ 


^^ 




1-3603 


38-39 


1-0125 


8-03 






1-35S6 


37-50 


1-0666 


7-14 






1-3473 


30-00 


1-0610 


6-25 






1-3360 


35-71 


1-0555- 


5-35 






1-3254 


34-82 


1-0402 


4-40 






1-3149 


33-93 


1-0450 


3-57 






1-3102 


33-03 


J-03S6 


2-67 






I-305B 


3214 


1-0343 


lis 




1 


k 




^ 


^ 



190 AGIO fRODUCTS. 

Book V, 4. ]\f |> Lavoisier attempted to ascertain tbe propor- 
< I y - tioa of the constituents of this acid, by itlfeastiring the 
M^^ qiuwitity of oxygen absorbed by a given weight of sul- 
phur during its combustion. His result was 71 parts 
of sulphur and 29 of oxygen. But this method was 
not susceptible of sufficient precision to warrant much 
confidence. Mr Thenard had recourse to a much bet- 
ler method *, which was employed still more lately for 
the same purpose by Mr Chenevix with ifiiich addressf • 
Nitric acid was distilled off 100 parts of pure ttlphar 
repeatedly till the whole sulphur wasconTtrted into aa 
acid. The sulphuric acid, thus formed/ was separated 
by means of barytes, with which it forma an insoluble 
compound. The 100 parts of sulphur, thus acidified^ 
yielded 694 parts of dry sulphate of barjtea. Hence 
100 parts of sulphate of barytes contain 14'5 parts of 
sulphur. This experiment was repeated by XQaproth 
with the same result. To know the portion of oxygen 
in sulphuric acid, it is only necessary to know the 
weight of sulphuric acid contained in dry sulphate of 
barytes. A great many experiments have been made 
to determine that point. Here Mr Chenevix seems ta 
have fallen into an error. Ht makes it only 2^ per 
ant. The analysis of Thenard indeed nearly agrees with 
his ; but all other chemists make it above 30 per cent. 
I consider the result obtained by Kirwan and Klaproth 
as the most accurate. They coincide, and find sulphate 
of barytes composed of 33 parts sulphuric acid and 
67 of barytes. Hence it follows, that sulphuric acid 



• Am, tie Cbim. mil a66. f /rub Tren*^ |80S| p. S33. 



r 



eomposed of 14-5 o£ sulphur, and 18 'i of ox-y^en ; 
rof 

*2'3 sulphur 
5T7 oxygen 



Ot 100 sulphuf and 136-5 oxygen". 

5 Sulphuric acid is not altered by the action of light AciiimoE 
norcaloric. Itdoes not combine with oxygen. Itwas "^S"" 
atErmed indeed by some chentists, that sulphuric acid 
might be combined with oxygen by distilling i[ off the 
black oxide of manganese ; but ihe assertion was re. 
futed by the experiments of Vauquelin. 

6. Noncof Che simple combustibles act upon it »t the Ofthetim* 
usual lemperaiure of the ntmosphcre, or at least iheit tn,i^ 
actioa is so slow as not to be perceptible : But when 
thvy are assisted by heal, ihty are all capable of de. 
posing it. 

WbcR sulphur is boiled in thit acid) it absorbs a por- 
tion of its oxygen, or at least combines with it, and the 
whole ii converted into ju/phurout acid. Phosphorus 
also absorbs oxygen from it by the assistance of heat, 
sulphurous add is driven oS, and phosphoric acid 
formed. At the boiling lempcralyre charcoal also ab< 
sotbs oxygen from it, and converts it into &ulphu> 
rooi acid. At a red heat it even converts it into sul- 
phur. When hydrogen gas and sulphuric acid are 
made to pass together through a red hot tube of porce- 
lain, the acid is completely decomposed, water is form- 
ed, and sulphur deposited t- 



" OehI«n'i /<^. »■ jc». 



Of the in 
bin, 



Oft 



ACID I-itODtJCTS. 

I. Aiote hu no stctioii on sulphuric acid ; but 

'. acid readily absorbs rouriaiic acid, and forms with it 
liquid of a brownish tin^e, which cuiils the dcr.K a 
suffocating odour of muriatic acid, and corrodes vcj 
table and «ven meiallic bodies near which it bappcnj 
be placed, 

fl. ^^'Ilen zinc Of iron is thrown into sutpharic 
ft violent action takes place, if the acid be diluted -, vrt 
ter is decomposed, iis hydrogen (lies off, and it»0Xi 
combines with the mcials. If the acid be conceulnie^ 
the action is much less violent, and sulphuious acid es> 
hales. Upon tin and copper the acid acts very slow^ 
and feebly, unless its action be assisted by beat whea 
oxidizes and dissolves ihem. On silver, mercury, ani 
mony, bismuth, arsenic, and lelluriuai, it does not 
except at a pretty high temperature. These mcnals 
■tract part of its oxygen, and convert one portion oCj 
to sulphurous acid, while another portion contHi 
with the oxides thus formed. When boiling hot It ( 
idizes lead, and dissolves cobalt, nickel, and taolybi 
num : But it has no perceptible action on gold nor p 
tinum at any tcmperaiore to which il can be raised. 

10. It unites readily with all the alkalies and card) 
except silica, and with most of the metallic oxides, ■ 
forms salts denominated lulplalcj. Thus the combii 
lion of sulphuric acid and soda is called tulpbatf of. 
the compound of sulphuric acid and lime, sulpbatt 
time, and so on . 

II. Itabsorbs i)v«rj> conaiderabtc quantity of nil 
gas, and acquires by that meant a purplish colour ' 



SULPflUROlfS. It3 

■ 

This is one of the most important of all (he acids, , ^.^P* ^, 
ot onl J to the chemist but to the manufacturer also ; 
eing employed to a very great extent in a variety of 
laonfactures, especially in dyeing. 



SECT. 11. 



6F SULPHtJROUS ACID. 



J. HOUGH some of the properties of this acid must have Hittoiy. 
been known in the remotest ages» as it is always form- 
ed during the slow combustion of sulphur^ Stahl was 
the first chemist who examined it, and pointed out its 
peculiar nature. He gave it the name oi pblogisticated 
mlfburic acid, from the supposition that it is a com- 
pound of sulphuric acid and phlogiston. His method of 
procuring it was to bum sulphur, and expose to its 
lames cloth dipped in a solution of potash. By this 
ooethod he obtained a combination of potash and sulphu- 
rous acid ; for sulphur forms by combustion only suU 
phurous acid. Scheele pointed out, in 1771, a method 
)f procuring sulphurous acid In quantities *• On Stahl's 
lalt he poured a portion of tartaric acid, and then ap* 
plied a gentle heat. The sulphurous acid is in this 
nanner displaced, because its affinity for potash is not 
(o strong as that of tartaric acid ; and it comes over in* 



* Schcek, i. 43« 



194 AGIO ?I(0PVCTS. 

Book w. to tbc receiver dissolved in water. Dx ft'vaflitj, io 
< ^ t 1 7749 obiaioed U in the gaseous form, ac^d eaa ^nfff dm 
properties while ia a state of purjitjr *• 9^rtb{^^ft pub* 
ished a dissertation 01^ its formation^ compofituw^ 8i|fl 
uses, in 1782 and 1789 1; and in 17Q7 appearedavcrf 
complete dissertation on its combinations bjr Fonrcrej 
and Vauquelm %• 
Prepan- 2. Sulphurous acid may be procured hj the follow- 

ing process : Put intp. a glMS retort two parts of mU 
phuric acid and one part of mercurj^aod applj the heit 
of a lamp : The mixture effiprvesceSy and • gas ismci 
from the beak of the retort, and maj be reoeived is 
glass jars filled with mercury, and standing in a men4- 
rial trough. This gas is julfhurous add. 
Fktipcnki. 2* Sulphurous acid, in the state of gas, is colonileii 
and invisible like common air. It is incapabkofmslB- 
taining combustion ; nor can animals breathe it with- 
out death. It has a strong and suffocating odour, pre. 
cisely the same with that exhaled by sulphur baniiig 
with a blue flame : sulphur, by such a combustion, be- 
ing totally converted into sulphurous acid. Its specific 
gravity, according to tlie experiments of Kirwan, h 
2*^265, that ot air being 1-000 : At the temperature of 
00^, barometer 30 inches, 100 cubic inches of this gss 
weigh 70'215 grains ||. 

3. This acid reddens vegetable blues, and gradnallj 
destroys the greater number of tliem. It exercises this 
power on a great variety of vegetable and animal co- 
lours. Hence the use of the fumes of sulphur in bleach* 



a On A'r, ii. iQf. t Mem, Par* 1781* Amm, it Cbim. iLj4. 



sCLFMUItOO;. 
iog n'oot knd in whitening linen stained by mean of , '^' I 

m Plandie ha« olnerv«d, that when syrup of violet?, 
p^yotviouilr leddened by itctcl«, it mixed with a little 
Mil|)lutrous acid, rhe orifrinal blue colour of the jymp 
it rettored, and its inieosilj* gradnally dtminiihci *. 

4. Dr PiieMloy discotereil, that when a strong heat 
is appltcd lo this acid in close rcHels, a. quanttrjof stil- 
phtir it precipitated, and the acid is convened into aul- 
phurkf. BrrtlioUei obtained the same rewih; bat 
toareny and VauqiKlin could not succeed J. 

According to Clotiet and Mong^, when this gas, in a 
>lxte of condensation, is exposed to the temperaiare of 
^16*, it is condcttscd into a liquid }. 

5. Walerabsorbsillis acid wilhrapidily. AccortJing Atiioi 
to Dr Priestley, j OOO grains of water, at the tcmperi- *"*'' 
mte iiS", absorb 33-0 grainj of li^is acid. Foorcroy, 

on the other hand, alTrtms, thai water at 40" absorbs 
the third^f its weight of snlphitroiis acid gas ^. Upon 
tryiog the experiment, I found that one cubic inch of 
vaicr at the temperature of 01' barometer 29*51! inches, 
absorbs 3S inches of gas. But sn inch of water weighs 
Kbofit 353* n5 grain*, and 33 inches of this gas weigli 
SS'lfi. Hence i( follows, that lUOO water in weight 
absorbs flt'5 of ihii gas. This exceeds cunsiderabl/ 
tbe mimate of Priestley, thmigh it comts short of that 
ofFonrcroy. Water impregnated with this gas ac- 
quires, according lo my eu peri men Is, the specific gravi* 
\y l-OM 3, even in as high a icmperaiure as os". Thi» 




■ An. d, Ctlm. It. SJi. 

f Om Air, li. jjo. I Ni>Iwhon^/«anM/,i. )lj 

I Four oujr, iL 74. lHjiip. ;j. 

N 2 



X96 AGIO rtODUCTS. 

Book II. water may be frozen without parUoff with Mr of tke 

Diviiion il. . *^ •* "^ . 

V acid gas. When water, which has been saturated wuh 

this acid at the freezing temperature^ is exposed to the 

heat of 65*25^ ^t is filled with a vast number of bnk 

blesy which continually increase and rise to the surboc. 

These bubbles are a part of the acid separating from il. 

It freezes a few degrees below 32^ *• 

or oxygen a. When liqnid sulphurous acid is ezpoeed to atmo> 

•od lift . . 

.spheric air or to oxjgen gas, it gradual! j combines with 
oxjgen, and is converted into sulphuric acid. This 
change takes place more completely iftheacidbecooh 
bined with an alkali or earth. When a mixture of lul- 
pliurous acid gas and oxjgen gas is ouide to pass tbroogh 
a red hot porcelain tube, the two bodies corobinCy sod 

n sulphuric acid is formed f • 

Of the 7» Of the simple combustibles, sulphur and phospho* 

other Sim- . ... , . , 

pic bodici, rus have no action on it whatever ; hydrogen gas sod 
charcoal do not alter it while cold, but at a red best 
they decompose it completely : water or carbonic acid 
is formed, and sulphur deposited %. 

Q. Neither azo.te nor muriatic acid produce any change 

on it. 

0. Sulphurous acid does not seem capable of oxidi- 
zing or dissolving any of the metals except iron, zinc, 
and manganese. 

10. It combines with alkalies, earths, and metallk 

oxides, and forms salts known by the uzmc of stiJjfAiiii. 

ofsulphu- II* Sulphuric acid absorbs this gas in coasiderabk 

ric acid. 



* Fourcroy and Vauquelin, Nicholson*! /wr. i- 3 i.i 
I- Priettlcy, il. ^^i. Fourcroy, ii. 74- 
t Fourcroy and Vauquelin. 




SVtFaOKOUB. 



IM 



mrilj. It acquires a yellowisli brown colour, a pe- ^'P- *'■ 
rating odoar, sod ihe properly of smoking when ex- 
i lo the air. When this mixture is distilleil, the 
vapour which comes over, and which if a com - 
of the two acids, crystsllizei in long while 
Irisms. This singular compound, formerly Icnown by 
tke Dsme of gloria! sulphuric acid, smokes in the air; 
tnd vrhcn the atmosphere is moist, melts with efl'erves- 
teDce. When thrown into water, it his&es like a red 
pot iron. Ii has ihc odour of sulphurous acid*. This 
Wrious compound, fir^l mentioned by Kunkel, and af- 
terwards by Bohn and by Neuman, attrncted a great 
Oeal of the attention of chemists, who attempted to in- 
llresligate the cause of its singular properlies. The ge- 
neral opinion, in consequence of the expcrimetits of 
ptellot, Wiegel, Meyer, and Gottling, was, that phlo- 
giston, some how or other, contributed lo its produc- 
tion. Dolfuszf made a set of experiments on it in 
a7S4 ; from which he concluded that it was peculiar 
to sulphate of iron, by the distillation of which it had 
Ken usually procured. These experiments were re- 
peated and varied by Morveau % ; and this philosopher 
fcoRStdered it as probable that the glacial acid is merely 
bnlpbnric acid, teitally deprived of moisture. Four* 
teroy has lately demonstrated that it is a compouild of 
bnlpbtiric and sulphurous acids. ' 

12. As this acid is formed by the combustion of sul- Compoij- 
fhnr, it cannot be doubled that it is composed of thft 
c ingredients with sulphuric acid ; and as it is evol- 



TMrcref, ii. 7S. 

1 £a^. Mrlbii. dim 



tCre:i'i4*™^j;8j.i.4,ll. 



IM A€ID t&ODUCXI. 

Book n. ved from sulplioric acid hy die sctton of Milpiwr, tol 
likewiie by some of the mculty it omnot be doubted 
that it contains a smaller proportion of .oxjgco. I ea* 
devroared tocsttraare the roiutitoants of this acid in tte 
fblloving anannar : By causing a rarrent of sulpku 
rons acid gas topass throngh a aolmion of carbonate of 
potash IB wateri I feoned Hie sahcaUcd sm/pik^affotm 
a$i. When this salt, previotisly dried upon Uaattag 
paper, ia exposed to the heat of 900^, it loaea 3^9 ftf 
Ma/» of its weight. When lOO graioa of U aroliaaiel 
to redness ia a platinum crucible^ the mIc dccffopiwi^ 
becomes of an opaque white, and cmita a Ifkm iane. 
By this treatment it loses 22*9 fir cent, and kawa ass 
rcsidwom splphate of potash. This sulphate of potaA 
contains 22*2£r of sulptmric add, the reat ia potash* 
Frocn thin analysis it felkws that sulphite of potash is 
£;oflaposed of 

23*30 Toiatile matter 
22' 25 sulphuric acid 
65*45 potash 



im* 



lOO-OO 

Wbcf) 100 grains of sulphite of potakh are healed in a 
retort attached to a mercurial appavatoSy there come 
Qver 18 cubic inches of sulphurops acidga^^ yi graias 
of sulphur, and a little water. The remaining aalt weighs 
77"> grains* and containa 23*2 sulphuric acidi the rat 
potash. From this analysis it follows th^t the 1 00 graiof 
of sulphite of potash were resolved iiUq 



L . 



I 



29*2 »o1phuric tcid ^{3iy.R 

5*1 sulphur 
54*5 potash 
17*2 sulpharoQS acid an^tmter 



100-0 

23*2 sulphuric acid and 5*1 of sulphur must 
fea tinited in the salt, and formed sulphurous a« 
f course, sulphurous acid is composed of 23*2 
ic acid and 5*1 sulphur, or^fer ctnt. of 

82 sulphuric acid 

18 sulphur 
Bra know the constituent! of sulphuric acid, it Is 
tnce to deduce the following as the prc^rtion 
igredienis of iulphtirovs acid : 
53 sulphttr 
47 ox/gen 



100 

sulfirhur and 88*6 oxfgeh; 






SECT. III. 



1 1 



Of I^HOSPHORIC ACIfi 



aoROSi like sulphur, forms an acid with two 
\ proportions of oxygen. Combined with a 
on of oxygen, it constitutes pbcspboric add ; 



t^O ACID PAODlfOrS. 



IXviftioti II. 



tion. 



I^L! 'ir ^'^'^ ^ smaller proporcioo, it coostitutrs pbospbortmt 
acid. 

Phosphoric acid remaioed unknoivn till after the dis« 
coveiy of 4^hosphorus» Boyle is perhaps the first cbe* 
mist who mentions it ; but Margraff first examined iti 
properties, and demonstrated i| to be a peculiar acid. 
Its properties were afterwards more oompletiely inves* 
tigated by Bergman, Scheele» Lavoisier, Pearson, Four* 
croj, and Vauquelio, and several o^her diatinguisbei 
chemists. 

Prfpara- 1* It may be formed by setting fire to a quantity of 

phosphorus contained in a :ressel filled with oxygen gu. 
The phosphorus bums with great rapidity, and a great 
number of white flakes are deposited, which arc/Aof- 
phoric acid in a state of purity. It may be obtained tOQ 
by heating phosphorus under water till it melt, and 
then causing a stream of oxygen gas to pass through it 
by means of a tube. In this case the acid as it forms 
combines with the water ; but the liquid may be eva- 
porated off* by the application of heat, and then the ad4 
remains behind in a state of purity. But the usual me* 
thod of procuring it is to throw phosphorus in small 
pieces at a time into hot nitric acid. A violent efferves- 
cence takes place, the phosphorus combines with oxy* 
gen, and nitrous gas is ehiitted. After the whole of the 
phosphorus is acidified, the liquid is to be evaporated 
to dryness, in order to drive off* the remains of nitric 
acid which may not have been decomposed. This pro- 
cess was first put in practice by Lavoisier. Care must 
be taken not to apply X(^o much heat, not to add top 
much phosphorus at once, and not to have the nitric 
acid too strong; otherwise the phosphorus takes fire, an^ 
usually breaks the vessels in pieces. When the acid 



r 



tUOSPHOUC. - 




pteparcd bf this metbod is c centrated and healed, I,t 
always em i Is a considerable quantity of t^hoiphureied 
bjrdrogcn gas, which burni anduccisions a considerable -^ 

loss. This loss may be dimiiiislied by cttutiously drop- '•• 

ping nitric acid iqio the hot mass. 

2. The acid thus prepared may be put into ft plati- Proptttict 
nam crucible, and heated lo redness, to diive ofT all tlie 
water. It is then in a siaie of purity. It is solid, co- 
lourless, and transpaient, and not unlike gla-,s ui ap- 
pcaraace. It reddens vegetable blues; it hasnosmc!!} 
its tssic is very acid, but it does not destroy Ihc tc^ciurc 
of organic bodies. 

When exposed to the opeu air, it soon attracts niuis- 
lure, and deliquesces into » thick uily -like liquid j iu 
which Slate it is usually kept by chemists. Wlicn ex- 
pos«ul to the iiie in a platinum crucible, its waicr gra- 
dually evaporuics, and leaves it in the slate of a trans- 
parent jelly. If the heat be increased it boils and bub- 
bles up, owing lo the «;paratioa of the remainder of its 
water, accompaoied wttli a .-mall portion of acid. At 
a red heat it assumts the foriu of a transparent liquid, 
and when cooled resembles the purest crystal. In this 
state it is known by the name of pboiphoric glasi. 
This glass is merely phosphoric acid totally deprived 
of water. It has an acid taste, is soluble in water, and 
deliquesces when exposed lo the air. At a red heat 
it c\-aporatcs very copiously in a white smoke, which 
has QO strong odour, unless the evaporation be prevented 
by ibe presence of a base. 

Tbc specific gravity of this acid, in a state of dryness. 



^:^y *l, it i-6fcT • ; in (he stute of Hus, i*S5i4 1 ; ill the tUte 

U ^, ,» 6t deliquescence, 1-41 tt* 

Action of J. -thh acW 15 very sdlhble in t^at^. Wflrti hiht 
sUte of Vfhitt flukes, it dissolves with a hissing noiiey 
similar to that made by ltd hot ir*^ plunged into wa. 
fer. When id the state of glass it dissolves much more 
slowly. The heat evolved daring the combinafibo of 
fbis acid and water is much inferior to thit evolftd 
when sutphurie acid efiters into a similar eaihbinatfdii. 
^osphbric acid obtained by deliquescence, wfien tdii* 
^ with an eqtial qnantity of distilled t^at^r, atqtiired 
so little teat as to raise the thermometer ifttljr one dr. 
gree, as Mr Sage observed. Mr tiaVoiitef raised the 
tikerffiOihetef fVom 50^ to OS* by mixing phoBph6ric 
geid, boiled to the consistence of a fyiiip, ^itti iff ^d 
quantity of water ; tnd firotn 50* t6 lo4* fkftdh the 
acid Was as thick as turpentine {. 

ActteflT 4. Otffaeii gas hns no action on pho§flhtiit teM, 

Sie^T^'^ whatever be the temperainre. Neither is h dilMihtK). 
sed or altered by any of the simple combnstibleiy' if lire 
except charcoal ^ ; which, though it has ntf ietita 6h h 
while cold, at ft ted heat decomposes it cotnpleHely ; csf. 
b6nic acid is formed, and phosph6rtrs sttbliited. this 
is the comtnon pt-ocess for obtaining phb^ohli. 

5. None of the simple incombtsfiblei kzv€ n^ par- 
ticnlar action oo it. 

6. This add, when in a liquid state» is cajMAfe of oil. 



a Bcrfnun*t Siitgraf^, p so. Smg, Trw. 
f Hmcpfrati, Jm. dc Clim. ixYoi. il« 
t £mtr€. Mtit'9 -. Chim, i. ill. 

i And ic:li»ft aiao h]r4ifgrD ; lu tbc cipcrioieDt hat not been 

A. 



rMOffHoitTC. lot 

dicing some of the meials, cspedally when assisted by Ctup. IL 
brai; u the Mme time hydrogen gas Is emilted. Hence 
w« see that the oxidiZctneol is owing to the decomposi- 
tion of water. In this manner it oxidizes iron, tin, 
lead, zinc, aoiiiaony, bismuth, manganese; but on 
M>me of these it acis very slowly. When fused wiih 
several of these metals, as tin, iron, and zinc, it is con* 
Trrt«4 tob) phosphorus ; a proof that they hsve a strong* 
er flfinity fat oxygen. 

Il does not >cl upon gold, platinum, silver, copper, 
RMTctiry, ersenic, cobalt, ricke). It appears, however, 
10 have *ome acfion on gold in the Jiy way, ai it it 
ailed t for when fused with gold-leaf it assumes a purple 
coloar : a proof that the gold has been oxidized. 

7- Phosphoric acid combines with alkalies, earths, n>cxph4tei> 
and metaitic oiides, and forms with thctn salts known 
by the name of pbos^bat ex. 

8. Thecotnponentpartsof this acid have been ascer- Cfmfod- 
taincd in * more satisfactory manner ihan almost any '""• 
Other chemical compound. Mr Lavoisier deduced from 
fail expeninents, that 45 parts of phosphorus, when burnt 
in oxygen, absorbed about €<i'313 parts of that gas, and 
produced about 1 1 4 parts of phosphoric acid*. But 
his mode of expen men ting was not susceptible of much 
precision. It consisted in burning phosphorus in oxy< 
geo gas, and ascertaining the increase of weight, whictl 
he ascribed to o&ygen. Mr Rose has lately publishod 
an elaborate set of experiments on the constituents of 
phospliDric acid. He acidifit^d the phosphorus by means 
of ijitrie acid, and ascertained the weight by combining 



$0^ ACID FROpUCTS. 

Book II. the gcid formed with oxide of lead. The result of his 

Division II. , 

kmi' ^ t expenmcDts was, that the acid was composed of 

46*5 phosphorus 
53*5 oxygen 



History. 



iOO'O 
or 100 phosphorus combioes with 114'75 of ozjgen, 
and forms 214*75 of phosphoric acid *• Some experi« 
ments, which I made in the same way nearlj, gave me 
a xesult a good .de^l different. I combiaed the add 
fpf me4 with lime. But as I do not recollect . the pro- 
poi;tion of acid which I estimated in phosphate of limci 
it is ii?ipossible to say how far my results di^eredfron 
those of Rose. 

Xhis acid is too expensive to he brought into jcommon 
use. If it could be procured at a cheap rate» it might 
be employed with advantage, not only in several import* 
ant chemical manufactures, but also in medicine, and 
perhaps even for the purpo^ of . domestic jeconoipy* • 



' ! ■ 



SECT. IV. 



OF PHOSPHOROUS ACID. 



J/he acid obtained by the burning of phosphorus dif. 
fers according to the rapidity of the combusticm ; or, 
which is the same thing, according to the temperature 



• Gchlcn*s /ffvrf 3d. Scries Ji. ^^*). 



raOSPHOROUS. SU5 

in which the process is conducted. When heated to . Q**P- ^'*^ 
148^, it bums rapidly, and the product r% phosphoric ^ 
acid ; when allowed to bum gradually, at the common 
temperature of the air, the product h phosphorous acid, '^ 

which contains a smaller proportion of oxygen. 'The 
difference between these two acids had been remarked 
by Sage, by Proust, and hf Morveau ; tut it was 'La:- 
voisier who first, in 1777, demonstrated that they form 
different compounds with other bodies,' and that the 
difference between them is owing to the different pro- 
portions of oxygen which they contain *. 

1. Phosphorous acid is prepared by exposing phos« Prq>ar»- 
phorus during some weeks: tcf the ordinary tempera- 
ture of the atmosphere. Even in winter the phos^ 
phoms undergoes a slow combustion, and is gradually 
changed into a liquid acid. For this purpose, it is 

usual to put small pieces of phosphorus on the inclined 
side of a glass funnel, through which the liquor which 
is formed drops into the bottle placed to receive it. 
From one ounce of phosphorus about three ounces of 
acid liquor may be thus prepared. It was called phlo* 
gisticated phosphoric acid by Morveau, from the suppo- 
sition that it is a compound of phosphoric acid and phlo- 
giston. 

2. Phosphorous acid, thus prepared, is a viscid liquid, Propc 
of different degrees of consistence, adhering like oil to 
the sides of the glass vessel in which it is contained. It 
emits the smell of garlic, especially when heated. Its 
taste is acid like that of phosphoric acid, and it produces 
the same effect upon vegetable colours. • Its speci/fc 
oravity has not been determined. 



• Mtrr. Psr, i;;:. 



S00 ACID nOBUClS. 

Bojka 9» It combiaei with water io ererj p co p ortioo ^ but 
\ , ^m it ctnnot, Kke phosphoric acid, be obuiacd in a cob* 

Crete sute« 
AcdoQ ef When healed, part of the water which it containi is 
^"^^^ at first evaporated. Then large bobbles of air rise to the 
surface ; there the/ break, and emit a dense white sinokir^ 
or even take fire if the experimesit be performed ia i|^ 
open vesieh The emission of these bubblea of pbotn 
pburcfied hydrogen gas continueafor a long time. Whcb 
the process is finished, the acid which remains is so 
longer phosphorous^ bat phosphoric acid* These phe- 
nomena show us, that phosphorous acid holds in solo. 
tion a certain portion of phosphorus, which at' a high 
temperature decomposes water, and is converted partlj 
into phosphoric acid, partly into phosphureted hydrogen. 
Of tiaipk 4* This acid is converted into phosphoric acid by ex- 
posure to air or oxygen gas. The process is exceed- 
ingly slow, and the conversion ia never complete. It 
succeeds better when the acid is diluted with a greac 
proportion of water *. 

5. Phosphorous acid is not acted upon by auy of the 
simple combustibles except charcoal^ and perhaps alsc: 
hydrogen. Charcoal decomposes it at a red heat m * 
well as phosphoric acid. The products are carbonx < 
acid and pliosphorus. It does uoi act on the aimpl • 
incombustiblcK. 

6. Its action on metals is exactly similar to that ^ 
phosphoric acid, excepting only that the hydrogen £s 
evolved during the oxidizemeM of the metals ha% 
fetid smell, and holds phosphorus in solution. 



bPdkt. 



• Faurcroy, il. 55. 



CASQOiriC- 



ea^ 



I 1. It combuies with alkdies, earths, aud meUlUcox- , Chap, n. 
ks, and farms compountU dlutugaished by the oame Pba^uiot 

^. Sulphuric add produces na change upon it while Action^ 
jpld ; bui at a boiling btat it paiis wiih some of ils 
IK/^en, and the (thosphoious acid is converted into 
j^osphoric acid. Nllric acid also, when assisted by 
h(«, convCTis it readily iniQ phosphoric acid. This 
^rnishes us with by far the best process for obtaioiag 
Ijlioiphonc acid at prcsenl known. Mix phos|jhorous 
4cid, obtained by slow combustion, wjth one-eighth of 
its wci^bl of oitiic acid of the specific gravity j-3, and 
distil. The nitric acid ts dccomposcdi and pure pho&> 
pbotic acid remains behind. For ttus process wc ar« 
indebted to Fourcroy *. 

This acid has not hitherto been put to any use. Th* 
hiitory of its preparition is suffkiciit to convince ut, 
tbuit ii composied of llic samcconstilueatsasphospho- 
fic acid : Bui ihc exact proporiion of thxse constilucntf 
f^Unot bitbcrto heca ascertaiued. 



I 



SF CARBOKIC ACIS. 



BR tlte rapid psognsi of chrniistr^, durinf^ the latter Hictof^ 
^t of the ISlh century, was iu a great measure owing 



Stod Acrb PRODUCTS. 

Book IT. iQ jj,e discovery of this acid, it may be worth while to 

Division II. , ■' ^ ' •' ^ 

trace the history of it somewhat particularly. 

Paracelsus and Van Helmont were acquainted witb' 
the fact, that air is extricated from limestone during cer- 
tain processes, and the latter gave to air thus produced 
the natne otgas. Rales ascertained the quantity af air 
that could be extricated from thes6 bodies }n diSeitot 
|}ro<:esseSy and showed that it formed an essential part 
of fheir composition. Dr Black proved that the nb- 
stances th^n called /r>vf , magnesia, and aUaHet, are coow 
pounds^ Consisting of a peculiar species of air^ and pore 
lime^ niagnesiai and alkali. To this species of air \A 
gave the name of Jixed air, because it existed in thesd 
bodies in a fixed stat^. This air or gas was afterwards 
investigated by Dr Priestley, and a great number of its 
properties ascertained. From these properties Mr Keir* 
first concluded that it was an acid ; and this opinion 
was soon confirmed by the experiments of Bergman, 
Fontana, &c. Dr Priestley at first suspected that this 
acid entered as an element into the coniDosition of at^ 
mospherical air ; and Bergman, adopting the same opi- 
nion, gave it the name of aerial acid4 Mr Bewdly cal- 
led it mepbitic acid, because it could not be respired 
without occasioning deatti ; and this name was also a- 
doptcd by Morveau. Mr Keir called it calcareous acid; 
and at last Mr Lavoisier, after discovering its compo- 
sition, gave it the name oi carbonic acid gas • 

For the investigation of the properties of carbonic 
acid wc are chiefly indebted to the labours of Caveiv- 



< Krlr*« Mtrcftfrr^ nrt. ■Hr 



CAHBONtC. 20p 

i»h ', Priestley +, Bergaian t, and LavoUicr §. Va- ci'^plL 
able dissertations on it were also pubtislied b^ Mac- 
idc II, Lane^, Jaicjuin "*, Laiidrianit+. Fontana, and 
aay other disiinguiihed chemist*. 

1. Carbonic acid, being a corapoiuid of carbon and Pupart- 
ixjrgcn, may be formed by burning charcoal ; but aj it ^'^' 
great abundance ready formed, there is no oc< 
ion to have recourse lo that expedient. All that is 
csnry is to dilute with water a quanriiy of chalk, 
rtuch is a compound of carbonic acid and lime, and to 
ir upon it sulphuric acid. An effervescence ensues, 
ic acid is evolved in the stale of gas, and may be 
Kived in the usual manner. 

3. Carbonic acid, when in the state of gas, is invi- Prapcrtiu 
able and elastic like common air. It extinguishes a 
euidle, and is unfit for respiration. It has no smelt. 

Its specific gravily, according to the experiments of 
Urwao, is 1*500, lliat of air being l-OCO ; or it is to 
3 10 2. At the temperature of 60", barometer 
,0 inches, 100 cubic inches of this gas weigh •lO'f- 
%%, From this considerable weight, compared to 
that of air, it happens that this gas may be poured 
Srorn one vessel lo another. When poured from a wide- 
nonthed vessel upon a burning candle, it extinguishes 
il Ukc water. 



■ PIU. TrvMi. ij66,l^ Mt- t PnatUj.i. 43- 

tOf^^lu i Mrm.Pjr. ij7«. 

I BmftrimattI Ejiaj.. tj64. 1 Prioller. '■ S- 
•• fiowi. a«>. Dia. Mrjrr, dt AciA Pi's-'- <* Br«if4M A At- 
!»,I7«9- 

t( C»«ir» AattU. 1781, il 139 It ltirw«n M i><%uft<i, p. %9 

Pol, //. O 



Book IT. 
DiviuoD IF. 



Action of 
#ater. 



ACID f RODUGTS. 

It reddens the tincture of turnsol, but no otber regw 
table colour *. 

Atmospheric air is supposed to contain about y^ 
part of this gasf . 

3. Carbonic acid is not altered by exposure to heat 
in close vessels^ or by passing it through a red hot 
tube. But ivhen ekctric sparks ar-e made to pas 
through it for a long time, its bulk is increased, as Dr 
Priestley first observed v and in that case^ as Mooges 
discovered^ an inflammable gas is always evolved* Bj 
18 hours labour Mr Saussure junior produced aaia* 
crease of ^j^ paf t of the whole ; one-tenth of the car« 
bonic acid had disappeared^ and a quantity of carbodc 
oxide had been formed^ The copper wires emplojred 
to transmit the sparks were oxidized at the expence of 
the acid^ which was thaa partially converted intacar* 
bonic oxide §. 

4. Water absorbs it gradvaUy when allowed to re« 
main long in contact with it. The rapidity of the ab- 
sorption, as Mr Lane first discovered^ is much increased 
by agitation. At the temperature of 41^ water absorbs 
its own bulk of this gas. The specific gravity of wa- 
ter saturated with it is I'OOiS.' This water, at the 
temperature of 33^, has little taste ; but if it be lefts 



• D( rj:iv.an, I. 9. 

f /\t least nvar the outface of the earth. Lamanon, Moog^, and the 
nther ur.ibrtunat«s phll^tnphcrs n^ho accompanied La Perouse in hit last 
voyage, have reixlered it m t improbable, that »f griat heights the quin<i 
tity of this gn^ U iDuch smaller. They couM detect none in the ttmot- 
f here at the AUinmit ot the Peak of Tciicriflc.— Sec Lamanon*» Memur 

tit tit end of La Ptrcujr*j Vbjagr. 



JBAABONICi £li 

few hours in the temperature of 88*", it as^dmes dti Chtp.Il. 
agreeable aciditj, and a sparkling appearance*. 

Ice absorbs no carbonic acid ; and if water cootainingv 
it be frozen, the whole separates in the act of freezing f. 
This gas also separates from water at the boiling tem- 
perature J. 

Bjr means of artificial pressure, the quantity of t)iis 
gms absorbed and condensed by water is much increased. 
Some of the aerated alialiae ^ater, prepared in Britain 
as a medicine, is said to contain about thrice its tolume 
of carbonic acid gas {• 

When this liquid carbonic acid is left exposed to tho 
air in an open vessel, the acid soon makes its escape in 
the form of gas, and leaves the water in a state of pu- 
rity* Bergman left a bottle filled with carbonic acid 
gas uncorked, and found that in a few days it contained 
nothing but common air. 

5* Carbonic acid is not acted upon by oxygen, nor Action or 
is it altered by any of the simple combustibles, incom- diet, 
bustibles, or metals* Charcoal indeed absorbs it, but it 
gives it out again fiUnchanged. From the experiments 
of Rouppe and Van Noorden> it appears that this ab- 
sorption is exceedingly rapid, provided the charcoal be 
sufBciently freed from air, by allowing it to cool from a 
red heat in a vacuum. They found that charcoal is ca- 
pable of abs'^rbing rather more than fourteen times its 
bulk of carbonic acid gas ^. These experiments have 
been confirmed by others made in a different way by 



• Bcrjrman, i. 9. f Priestley, i. 1 20. \ Ibid. 

} A vciy con vcr lent apparatus for this purpose has been contrived hf 
Mr Gilbtn Austin, and described in the Irish Tr€H4aetiMt,vul. 131. 
^ ^nn. de CSim. XXXU. ll. 

O2 - 



ACID PRODUCTS. 

Count Moroizo *. At > red heat charcoal cofiTerli f| 
' into carbonic oxide gas. 

Phosphorus is imoluble in carbonic scid gas f; faul: 
phosphorus is cajtablc of decomposing this acid bjrc 
pound ailinity, when assisted by aniflictent heat, as hn 
been demonslrated by Tcnnanl and Pearson. Iron all* 
and zinc, and several other metals, are capable of pro- 
duting ihc same effect, as has been discovered by Priest* 
ley and Cruikshanks. Tn the first case the phosphor 
is partly acidified, partly combined with lime, and charh 
cobl is deposited : in the second, the metals arc oiidi^ 
led, and the guscous oxide of carbon evolved. 

When carbonic acid is mixetl with mlphnivte^ 
phosphureted, or carbureted hydrogen gat, it re 
them less combnsttbic, but produces no farther scniibU' 
change. 

fl. This acid is capable of cmnbining with aUttliei^ 
and with several of the earths and metallic oxides, aad' 
forms with them sslts, distinguished by the name oT 
carbonatn. All the earthy carbtonaies are insolublen 
water. Hence the reason that car^nic acid rendeif- 
lime water, baryies water, and stroniian water turbtdi- 
The earth held in solution in these waters combines n** 
pidly with the carbonic acid, which is of course ab^ 
sorbcd, if in the stale of gas, while the carbonate fonih- 
ed precipitates slowly in the form of a white powder. 
This occasions the niilkincss which immediately c 
sues. As carbonic acid is the only gas not inttanta-- 
Mously absorbable by water, which renders lime wt^! 



'Michoriai'i ymnoJ. ii. s6s. 

t Fcwtfcy vidVaD^MliiH lbld.xii.ao;.~ 



«■■ 



CAKBONIC. M'ft 

:, or bffftk or itrontiaa water, turbid, its presence Chap-ir. 
-may be always ascertaiacd by means of lliesc liquids. 
it U completely absorbed by ihem, it may be easily 
separated by them from other gases with which it may 
be mixed, and tisqaaniity ascertained by the diminu- 
tioa of voluiDe which the residuum of gas hai under- 
gone. 

7. From the experiments of Saussurc, it appears that 
carbonic acid scarcely combines with alumina *. 

Water containing a little soda, and supersaturated 
witb carbonic acid, has been employed with much ad- 
vantage under t!ie name of aerated alkaline water, as a 
palliative in cases of urinary calculus. 

S. The opinions of chemists concerning the com/oji- CompMi- 
/ton of carbonic acid have undergone as many revolu- 
tions as its name. Dr Priestley and Bergman seem at 
iast to have considered it as an element ; and several 
celebrated chemists maintained that it was the acidify- 
ing principle. Afterwards it was discovered to be a 
compound, and that oxygen gas was one of its compo- 
nent parts. UpoD this discovery the prevalent opinion 
of chemists was, that it consisted of orygen and phlo- 
giston ; and when hydrogen and phlogiston came (ac- 
cording to Mr Kitwan's theory) to signify the same 
thing, it was of course maintained that carbonic acid 
was composed of oxygen and hydrogen : and though 
Mr Lavoisier demonstrated, that it was formed by the 
combination of carbon and oxygen, this did not prevent 
the old theory from being maintained; because carhon 
WM itself considered as a compound, into which a vety 



"jw.irPtj-.Ui.aio 



914 ACTD PRODUCTS. 

Book IT. great qiitntity of hydrogen entered. Bat after Mr 

Division ••••... -TO , ^ 

Lavoisier had demonsTrated, that the weight of the car. 
bonic acid produced was precisely equal to the charcoal 
and oxygen emplojed ; after Mr Cavendish had dis- 
covered that oxy/>en and hydrogen when combined did 
not form carbonic acid, but water^-rit was no longer 
possible to hebiiate that this acid was composed of cir* 
bi*n and oxygen. Accordingly all farther dispute aboiu 
it seems now at an cMi. At any rate, as we have al- 
ready examined the objections that have been made to 
this conclusion, it would be improper to enter npoo 
them here. From the experiments of BTr Smiihson 
Tcnnant, compared with thn«;e ot Lavoisier, and Messrs 
Allen and Pepys, we may consider carbonic acid as 
composed of about 

28 carbon 
T2 oxygen 



100 

r^-comj-osi- If any thing was siill wanting to put this conclusroa 
'^' beyond the reach of doubt, it was to dtcompound ckx\^* 

nic iic'd, and thus to exhibit its component parts bj 
analysis as well as synthesis.. This has been actually 
done by the ingenious Mr Ter.iiant. Into a tube of glass 
he introduced a bit of phosphorus and some carbonate 
of lime. He then staled the tube hermetically, and ap- 
plied heat. Phosphate of lime was formed, and a 
quantity of charcoal deposited. Now phosphate of 
lime is composed of phosphoric acid and lime ; and 
phosphoric acid is composed of phosphorus and oxygen. 
The subaiaroes introduced into the tube were phospho« 
rus, lime, aju' cr.ih< i;ii acid ; and the subsrnnces foond 
in it wcic pl^.os['horu% lime, cxygcn, ai;d charcoaL 



FLUORIC. 

e carbonic acid, therefore, must have been decom« 
«dy and it must have consisted of oxygen and char- 
1. This experiment was j^peated by Dr Pearson, 
lO ascertained that the weight of the oxygen and 
ircoal were iogether equal to that of the carbonic acid 
lich had been introdiiced : and in order to show that 
evas the carbonic acid which had been .decomposed, 
introduced pure lime and .phosphorus ; and instead 
obtaining phosphate of lime smd carbon, he got no- 
ng but phosphuret of lime, lliese experiments* 
re also confirmed by Messrs Fourcroy, Vauquelia, 
Ivestre, and Broigniart f. 




SECT. VL 



X)F FLUORIC ACID. 



HE mineral called fluor or fusible spar^ and in this Hittoiy^ 
i^ntry Derbyshire spavy was not properly distinguish- 
from other spars till MargrafF published a disserta- 
m on it in thv Berlin Transactions for 1768. He 
St proved that it contained no sulphuric acid as had 
en formerly supposed ; 'he then attempted to decom- 



* jU». deCiim. xiii. Jia. 

' Count Mus8tu*Pttsahkin 'haTing boiled a tolotion of carbonate of 
aih on pirified phosphorus, obtained charcoal. Thb he considered 
ID ioitance of the dcconipo^icion of carbolic acid, ^nd as a confimiarion 
he eiq?<riineiiti related in the text. See AjtK, 4e Cbim, zvr. 105. 



SIO 



AC7D PRODUCTS. 



Book 1 1. 
Division II. 



Prepan- 
tiofu 



pose it by mixing together equal quiotities of this mx» 
heral and sulf^huric acid^ and distilling them. By tUk 
method he obtained a wbite svilimate, which he snp^ 
posed to be the flaor itself volatiliied by the add. He 
observed with astonishment that the glass retort was 
corroded, and even pierced with holes. Nothing mor^ 
was known concerning fluor till Schcele published bis 
experiments three years after; by which he proved tbsl 
it is composed chiefly of lime and a particuhtr add^ 
which has been culled fluoric acid. 

It is always obtained from flnor spar, in which nune* 
ral it is found in abundance. For the investigatioo 
of the properties of this acid, we are indebted chiefly to 
Schecle and Priestley. 

1. It may be obtained by putting a quantity of the 
spar in powder into a retort, pouring over it an equil 
quantity of sulphuric acid, and then applying a voj 
gentle heat. A gas issues from the beak of the retert, 
which may be received in the usual manner in glsn 
jars standing over mercury. ' This gas hjbtorif mdd^* 

The acid may be obtained dissolved . in water bj 
luting to the retort a receiver containing water. The 
distillation is to be conducted with a very* moderate 
heat, not only to allow the gas to condense^ but alao to 
prevent the fluor itself from subliming. After the pro- 
cessy provided a glass retort has been employed^ m cnni 
of white earth is found in the receiver, which has all 
the properties of silica. 



* In order to obtiin tbit acid pure, platinm or iOvw vcMck oa^ to 
keempbyed; for the acid diMolTei a portico olglMiHidefai of Iota 

VffMCll. 



bclicek supposed ihat the silica produced wns forir- 
«d of fluoric acid and water i and BcTgtnnn adopted the 
•ame cpinion. But Wiegleb and Bucholz showed that 
ihe quantity of silica was exactly equal to whai (hv re- 
tort lost in H-eighl ; and Meyer cotnpkted 'ihe proof 
that it was derived from tl:e glass, by the following ex- 
periment: He put into each of three equal cylindrical 
Itn vessels a tniiture of three ounces of sulpliiiric: acid 
Old one oQDce of fluor, which had been pulverized in a 
mortar of metal. Into the first he put one ounce of 
pounded glass ; into the second, the same quantity of 
quartz in powder ; and into the third, noihing. Above 
each of the vessels he hung a sponge moistened with 
water; and having covered them, he exposed them to 
S moderate heat. The sponge in the first cylinder was 
covered with the crust in half an hour: the sponge in 
the second, in two hours ; but no crust was formed in 
ihc third, though it was exposed several dayi. In con. 
sequence of this decisive esperiroent Bergman gave up 
his opinion, and wrote an account of Meyer's experi- 
tncnt to Moirveau, who wasemploycd in translating his 
works, to enable bim to correct the mistake in his notes. 

Soon after the discovery of this acid, difEculties and 
doubts concerning its existence as a peculiar acid were 
stalled by some French chemists, disguised under the 
name of Boulanger, and afterwards by Mr Achard and 
Mr Monnet. To remove these objcciions Mr Scheele 
iastiiuted and published a new set of experiments ; 
which not only completely established the peculiar na- 
ture of the fluoric acid, but once more displayed the 
aorlvalled abilities of the illustrious discoverer". It 




d CreU'i 



,i7M,i. 



«18 



ACID FKODUCTS. 



Action of 
water. 



Book II. would be needless to enumerate these objections, as thej 
<■■■ ^ I > originated entirely Irotn want of precision, and did not 

produce a single convert. 
Propertiet. 2« Fluoric acid gas is invisible and elastic like air; 
it does not maintain combustion, nor can aninntU breathe 
it without death. It has a pungent smell, not unlike 
that of muriatic acid« It is heavier than common air. 
It corrodes the skin almost instantly. 

3. Neither caloric nor light produce any alteration oa 
it. 

4- When water is admitted in contact with this ga^ 
it absorbs it rapidly ; and if the gas has been obtained 
by means of glass vessels, it deposits at the same time a 
quantity of silica« 

Water absorbs a considerable proportion of this gai^ 
but fhe precise quantity has not been determined. l*be 
compound is usually termed Jiuoric acid by chemisti. 
It is specifically heavier than water, has an acid taste, 
reddens vegetable blues, and does not freeze till cooled 
down to 26^ *. When licatcd, the acid gas is easily 
expelled, except the last portions of it, which adhere 
with great obstinacy. 

5. Ncitlier oxygen gas nor any of the simple coni« 
bustiblcs or incoipbustibles produce any chaiige on fla- 
oric acid, either in the gaseous or liquid state. 

6. Fluoric acid gas does not act upon any of the men- 
tals ; but liquid fluoric acid is capable of oxidizing iroii^ 
zinc, copper, and arsenic. It docs not act upon gold, 
platinum, silver^ mercury, lead, tin, antimony, cobalt. 

rluate*. *!• It combines with alkalies, earths, and metallic ov 



Of •iBiple 
bodick. 



* Pritbtlcy, ii. 361. 



id«t, and forms with them salts which are denomlDatcd . *^ '. 

The most singular property of fluoric acid is the fa- 
cility wiih which it corrodes glass and siliceous bodies, 
npcciallj when bat, and the ease with which it holds 
silica in solution even when in the siaie of gas. This 
■ffinily' for silica is so great, that the thickest glass ves- 
lels can only withstand its action for a shoit time ; and 
the greatest precauiiont are scarcely sut&cient to obtain 
^t entirely free from !>iliceous eanli. 
I B. It produces no change, a& far as is known, upon 
'■ny of the acids already described. 

0, As fliioric acid produces an insoluble compound 
'with lime, it may be trnplojcd wiih great advantage, 
:U Pelkiier has observed, to delect the presence of that 
earth when held in solution. A drop or two of the 
acid causes a milky cloud or precipitate la appear, if 
«ny lime be present. The properly which this acid has Vudfar 
ofcoTioding glass, has induced several ingenious men gliii. ° 
"lo atlem)it, by means of it, lo enjirare, or rather etch 
f'tipon glass. The glass is covered completely with wax ; 
; tuid then that part where the letters or ligurcs are to ap. 
Ipear is laid bare by removing the wax. The whole is 
then exposed for some time to the hot vapours of fluo- 
^ TIC acid. This simple process is employed with ad- 
, vautage in writing labels on glnss vessels, and in gradu- 
I sting ihermometerSj and other similar instruments. The 
I' discovery is by no means new : It has been shown by 
Beckman and Accum, that this acid was employed fot 
I (hat purpose by Henry Swanhard, an artist of Nurem- 
bctg^ as early as 1610. Ue seems to have kept hit. 



2'20 



ACID FHODUCTS. 



Ho»k II. 
DiTision 11. 

Compoii- 

ticn. 



art for some time secret ; but the receipt was made pub- 
lic by Pauli in 1725*. 

Till lately we were entirely ignorant of the oonsti- 
tuents of this acid. Dr Henry tried in vain to decom- 
pose it by means of electricity ; but Mr Davy's late 
attempts have been more successful. Potassium has 
the property of decomposing it, and the decompoutioo 
is attended with combustion f • A proof that ozjgen ii 
one of its constituents. The base of the acid is analo- 
gous to sulphur {• It combines with the potash fimn* 
cd, or with the potassium if there be an exceu of that 
substance. It is combustible, and produces by its 
combustion fluoric acid. Hence it is obvious that thu 
acid is truly an acid product. No name .has hitbeito 
been given to its peculiar basis* 



' , '■ * 



« See Bcckman*! Hht»ry •/Jmmtniim$t and Accoin, Midwhoa't/ar^ 
m/. !▼. X. — The foUowbg advertitement, publbhed by tbeM 
tttm m German pnblicatKin of I7t5, will gire an idea of the 
ployed by that aititt. '* Take spiritut ni^ per diHillatiofiH, ptt k 
into a retort, and apply a itrong heat. ,When it hat p a wed o«cr ioto tk 
receiver, throw into it tome powdered green B^htmiam 9wmwU (wfckk, 
when heated, Aines in the dark), otherwise called ttt^b^rm, Thiite> 
ing done, place the receiver, containing the miitiire^ on a hotsd fmA* 
bath for about foDr.and<twemy honra, and it will .be fit te iIm pnipwu 
To use this corrosive acid, take a pane of glaia of any kiad, deaa it m^ 
and free It from grease by washing with a ley ; and when dry. trace ttt 
upon it, with tolphar and vimish, whatever yoB chooie. Pot a tmder 
ci beet wax round it about one inch high, and then poor the caonkK 
acid, prepared as before directed, carefully over the wbok wriKe of]^ 
j^lass, and let it stand uudistarbed for some time ; the longer the bccttr. 
The glass will become corroded ; and all you had traced befec« wiD aow 
appear as if rai«d, or elevated, above the surface of the gbn, ta a very 
tlistinct and pleaiong manner.** The hesphoms here mentioned v 
(lently fluor spar. 

t PbiL hUg, iniii. 89. \ Nicholion*s JoKrngl, uii. tj8 



I BE word borax first occars in the wor^s of Geber, Hinwy- 
hi Arvbisn chemist of the lOlh cencury. It is *. nunc 
given to a species of white salt much used t>y various 
knists. Its use in soldering metals appears to have 
teen known to Agricola. 

Bora^: ts found mixed with other substances in Tiii- 

\a. It seems lo exist in some lands adjacent to lakes, 

Erom which it is extracted bj water, and deposited iu 

bose lakes; whence in summer, when the water is 

Siallow, it is extracted and carried off in large lumps. 

lomettmes the water in these lakes is admitted into re- 

trroin; at the bottom of which, when the water is 

Sbaledbf the summer's heat, this salt is found. Hence 

t U carried to the East Indies, where it is in some 

leasure purified and crystallized : in this state it comes 

Knrope, and is called tinea/. In other parts of Thi- 

It, it seems, by accounts received from China, [hey 

\g it out of the ground at the depth of about two yards, 

here they find it in smaller crystalline masses, called 

Xhc Ch\ae\e tni poun, boui poira, a.x\i pin ftouia ; and 

earth or ore is called pvunxa *. 

Though borax has been in common use for nearly 

centuries, it was only ia 1702 tbal Homberg, by 



Q22 ACID PRODUCT^. 



Dtvision II. 



^h^l^nflir <iistilling a mixture of borax and green vitriol, diico' 
vered the boracic acid. He called it narcotic or sedatim 
salt^ from a notion of his that it possessed the proper- 
ties indicated by these fiames. In his opinioo, it wis 
merely a product of the vitriol which he had used} but 
Lemery the Younger soon after discovered, that itcouU 
likewise be obtained from borax by means of the nitric 
and muriatic acids. Geofiroy afterwards discovcnd 
that borax contained soda ; and at last Baron proved 
by a number of experiments^ that borax is composed 
of boracic acid and soda ; that it may be reprodnord bf 
combining these two substances ; and that therefore the 
boracic acid is not formed during the decomposition of 
borax, as former chemists had imagined, but is a pecn* 
liar substance which pre-existed in that salt. 

This conclusion has been called in question by Mr 
Cadet * ; who affirmed, that it was composed of nda^ 
the vitrifiabli earth of copper ^ another unknown metal, out 
muriatic aciiL But this assertion has never been coo- 
firmed by a single proof. Mr Cadet has only proved, 
that boracic acid sometimes contains copper ; and Bio* 
Die's experiments are suilicient to convince us, thatthb 
metal is merely accidentally present, and that it is pro* 
bably derived from the vessels employed in crystalli- 
7.ing borax ; that boracic acid generally -contains a little 
of the acid employed to separate it from the soda with 
which it is combined in borax; and that crude borax 
contains a quantity of earth imperfectly saturated with 
boracic acid. All which may be very true ; but they 
lire altogether insufficient to prove that boracic acid i^ 



« Ji^MT.JePhs. 178:. 



SORACIC. d2S 

Hot a peculiar substance, since it displays properties ^ > 

different from every other body, 

Messrs Exschaquet and Struve * have endeavoured, 
on the other hand, to prove, that the phosphoric and 
boracic acids are the same. But their experiments 
merely show, that the^e acids resemble one another in 
several particulars > and though they add considerably 
to our knowledge of the properties of the phosphoric 
«cidy they are quite inadequate to establish the principle 
which these chemists had in view ; since it is not suf- 
ficient to prove the identity of the two acids, to show 
us a resemblance in a few particulars, while they differ 
in many others. Boracic acid must therefore be consi- 
dered as a distinct substance. ' 

1. The easiest method of procuring boracic acid is Prep^n* 
the following one : Dissolve borax in hot water, and 

filter the solution ; then add sulphnric acid, by little and 
little, till the liquid has a sensibly acid taste. Lay it 
aside to cool, and a great number of small shining lami- 
nated crystals will form. These are the boracic acid. 
They are to be washed with cold water, and drained 
upon brown paper. 

2. Boracic acid, thus procured, is in the form of thin Propcrtlet. 
hexagonal scales, of a silvery whiteness, having some 
resemblance to sj;ermaceii, and the same kind of greasy 

feel. It has a sourish taste at first +, then makes a bit- 
terish cooling impression, and at last leaves an agreeable 
sweetness. It has no smelJ j but when sulphuric acid 



* 'Jour, (fe Ph\s, xxvlii. ii6. 

I Owing most probably to th? remains of the acid employed in pio- 
ctirin J i: ; for it bscs that taste when heated to redness. 



;224 



ACID PRODUCTS. 



Book If. 
DivisIOQ H« 



Action of 
water. 



Of Minple 
bodietv 



is poured on it, a transient odour of innsk is prodol 
ccd*. 

It reddens vegetable blues. Its specific gmvity is 
1-479 1 while in the form of scales ; after it has been 
fused it is 1*803 t. 

3. It is not altered by light. It is perCectlj fixed ia 
the fire. At a red heat it melts, and is converted into 
a hard transparent glass ; which becomes somewhst 
opaque when exposed to the air, but does not attrset 
moisture. 

4. It is much less soluble in water than anj of tbe 
acids hitherto described. Boiling water scarcely dis- 
solves 0*02 of boracic acid, and cold water a still smaller 
quantity. When this solution is distilled in dose ves- 
sels, part of the acid evaporates along with the walcr/ 
and crystallizes in the receiver. Water, therefore, la^ 
ders it in some measure volatile, though it bpe r fed iy 
fixed when in a state of dryness. 

5. Neither oxygen gas, the simple CombustiUes^the 
simple incombustibles, nor the metak, produce soj 
change upon boracic acid/ as far as is at present knowa. 

6. It is soluble in alcohol ; and alcohol containing it 
bums with a green flame. Paper dipped into a solution 
of boracic acid burns with a green flame. 

Though mixed with fine powder of charcoal, it is ne- 
vertheless capable of vitrification ; and with soot it melts 
into a black bitumen*like mass, which is, however, so- 
luble in water, and cannot be easily calcined to ashes, 
but sublimes in part ^>. 



* Reuu, ^f SmU SeJat. I 778. 

t Haofcnfinci, Ak»* d* CLi'm. xxviii. 11. 



t Kirwan*! AK*. ii. 4. 
$ Keir't Dktkmwy. 



Fi the asststuice of a disiilUng heat, it dissolves in 
pedally in minei^ oils ; and with the« it yields — ' 
id solid products, which give a green colour to 

en boracic acid is rubbed with phosphorus, it 
ot prevent its inflammation ; but aii earthy ycl- 
uter is left behind*. 

ihirdljr capable of oxidixing or dissolving anyof 
ilali except iron and zinc, and perhaps copper. 
Kic acid combines with alkalies, alkaline earths, 
tmina, and most of the meiattic oxides, and forms 
onds which are called borales. 

component parts of this acid were till larely un- Conpoii- 
. Fabroni announced that he considers it as a 
ntion of muriatic acid, and that it may be pre- 
[rom that acid ; but he has not yet published the 
noents upon which these opinions are founded f . 
curious set of experiments have been made on it 
;11. By digesting oxymuriatic acid on it for a 
mg dme, he succeeded in decomposing il, and 
k1 from it a substance exactly resembling char- 
Its properties, and a volatile acid resembling the 
ic in the greater number of its properues, but 
ig firom it in not precipitating lead from its solu- 
Mr Davy has succeeded in decomposing this 
f means of potassium, and has shown that it is 
sed of oxygen, and a combustible basis of a black 



t Foarcrof, u, ilS. 
Dnudcn tlui votacile acid a> itej 



f2# 



ACii>^ f RODuen* 



Book n. colour, which has a ereater resemblance to cbanmt 
than to aoy other substance *m It becomes whitc^ and 
is doubtless converted into boracic acid bj exposuce t» 
the air. 



« >ncMMMi't Jmr. ai. s Jt» 



Ii 



r 



A6ID tnttXTXMii Mf 



CLASS II. 



ACID SUPPORTERS. 



^a^ 



acid supporters are distinguished bjr the follow- propertitfli 

operties : 

fhey cannot be produced bj combastioil. Hence 

>ase is either a simple incombustible ot a ihetallic 

rhej are capable of supporting coihbustion • Hehce 
eadilj acidify the combustible bases, and convert 
)f the metals into oxides. 

rhey are decomposed by exposure to a high teiil« 
xe ; their oxygen in that case making its escape 
state oPa gas. 

i only acids which possess these properties in per- 
1 are those which have the simple incombustibles 
'senic for their bases ; but from analogy 1 refer 
hole of the metallic acids to this head. None ot 
can be produced by combustion ; and as they 
n a maximum of oxygen, they are of course in« 
istible : They cannot^ therefore^ be referred to any 
other two classes* 

Pfi 



228 



ACID SUPP6ftT£t& 



Bookir. 




,1^ The following Table cxhibiu a view of all tbe icB 
sopportersy their composition^ and the pro p o rt ion of 
their constituents, as far as they have been ascertained. 



Rvmbcr 

aiidooBpo- 

•tinn. 



1 

Acidi. 


w 


OxjfCBtotoo 
Bate. 


Nitric 
Nitrooa 


Azote 


236 


Oxjmuriatic 
Hyperoxymuriatic 


Muriatic acid 


20 
194 


Arsenic 


Anenic 


53 


Tunptic 


Tungsten 


25 


Molybdic 


Sfolybdenum 


50 


Chromic 


Chroouwn 


800 


Columbic 


Columbium 





Some of these acids are of great importnce in che- 
mistry. This is chiefly owing to their activity i far 
which they are indebted to the state of die osygea 
which they cirfitain. The theory of Lavoisier appliei 
with precision to this class of adds as well as to As 
first. 



OF WTRIC ACID. 

; US ACID seems to have been iirsi obtaioed in a Hinory. 
te slate by Raymond Lully, who was born at Ma- 
il 1235. He procured ii by distilling a mixture 
e snd clay. Basil Valentine, who lived in the 
entury, describes the process minutely, and calls 
id wattr of nitre. It was afterwards denomina- 
•aajortii and ipirit of nitre. The name nitric acid 
rat given it in nST by the Frencti chemists. 
It is generally obtained in large manufactories by _^'P"^ 
lag * mixture of nitre and clay ; but the acid pro* 
by this process is weak and impure. Cheioists 
ally prepare it by distilling three parrs of nitre 
De of sulphuric acid in a glass retort. This me- 
nras first used by Glauber. The neck of the re- 
BtiM be luted into a receiver, from which there 
i A glass lube into a bottle with two mouths, con- 
\g ft little water, and furnished with a tube of safe. 
From the other mouth of this bottle there passu 



tnbeaf Bffty Ita (ube <^o»t iuupper end. ind hiving in 1 
»d phulfcd Id watrr. The wiier prevent! any comninnintiiH I 
in the citcnul air ind ihe inude n( the apparaiui. If a vacuiw 
• to be romed within the tckcIi, ihe citemi] air njihci dovii 
k iht tube and prtiemi any injury to the vtueli. On the other 
iS»ir U goKntti in the veniJi, it lorco (he laaier up the tube, 
ighl of which fceeomei thntihe meaiurc of ihe elaMiciiy of the air 
itmeh. B] this tontriTance the appiniui ia in no danger of be- 
ikcs, mUdk othcTwiM might hippw. 



250 ACID STTTFOItTEM. 

Book H. a tube into a pneumatic apparatus to collect the gu 
which is evolved during the process. The apparatni 
is represented in fig. 12. The retort is to be hetted 
gradually almost to redness. The nitric acid comet 
over and is condensed in the receiver, ivhile the con. 
mon air of the vessels, and a quantity of oxjgen gu 
which is evolved, especially towards the end of the pco- 
cess, passes into the pneumatic apparatus, and the wu 
ter in the bottles is impregnated with some acid which 
it not condensed in the receiver. 

The acid, thus obtained, is of a yellow colour, and 
almost always contains muriatic and sulphuric acid, from 
which it is difficult to free it completely. Perhaps the 
best way is to purify the nitre beforehand by repettcd 
crystallizations, and by throwing down the muriatic add 
«that may adhere after all, by means of nitrate of silver. 
From the experiments of Lassone and Comette, it ap. 
pears that if nitric acid contaminated with muriatic be 
distilled with precauiion, tlie whole of the muriatic add 
comes over with the first portions, and the last poriioos 
are quite free from it *. The common method is to mix 
impure nitric acid with nitrate of silver, to separate the 
precipitate, and re-distil. This method succeeds only 
when the acid is strong ; if it be weak, a portion of mo* 
riatic acid still adheres to it. The sulphuric tcid may 
be separated by rectifying the acid, by distilling it slow- 
ly, and withholding the last portions, or by diatilliogit 
pfF litharge or nitrate of barytes. • 

After these foreign bodies are separated, the acid still 
fet^ins a quantity of nitrous gas, to which it owes its 



♦ Jl/fK. ^^r. X/Sii f. 645, 



xrniic. sst 

i she red fumes which Jl exhales. This gas ^ Qw p iz. 
« expelled by the application of heat. Pure nitric 
irid remains behind, tnnsparent and colourless, like 
Vater. 

2- When newly prepared in this manner, il is a li- Properties. 
|uic! zs transparent and colourless as water ; but the 
SSnicy between its component parts is so weak, that the 
Iction of light is sufficient to drive off a part of its oxy- 
[en in the form of gas ; and thus, by convening it 
lartly into nitrous gas, to make it assume a yellow co- 
BOr. Its taste is rxcecdingly acid and peculiar. It is 
try corrosive, and linges the &kin of a yellow colour, 
rbich does not disappear till the epidermis comes off. 
t is constantly emitting » hite fumes, w^ich have an a- 
rid and disagreeable odour. 

3. Il hasa strong affinity for water, andhasneveryet Attion< 
wen obiained except mi:ccd uiih that litjuid. When 
Dncentraied, it attracts moisluie from the atmcspherc, 
lOt not so powerfully as sulphuric scrd. It also pro- 
bees heat when mixed with water, owing cridenily to 
ke coaccntration of the water. 

' The specific grivily of the strongest nitric acid thai 
In be procured is, according toRouelle, 1*583 ; but 
I the lempcraturc of 00", MrlCirwan could not pto- 
ire it stronger than 1-5543, 

But as this liquid acid is a compound of two I'ngre- "^'^'l - 
lents, namely, pure nitric acid and water, it becomes nitm laid. 
A object*of tile greatest consequence to ascertain the 
roportion of each of ihese pans. This problem has 
Itcly occupied the attention of Mr Kirwan, who has 
jdeavoured to solve it in the following manner. 
He dried a quantity of crystallized carbonate of soda 
^« led heat and dissolved it in water, in such a pro- 



1 



ACID BpirqtTfxs. 

pQtttoa tliBt Ml giaiiis uf the tolutios coaUiBcd 50'0^ 
of xlkali. He salutaled 361 grains of this 
with 141 grains of nitric acid, the spccilic gravity 
which was l-i;i54, and which he ascettaincd to 
4S"i fit'' ffit- o( acid, of the specific gravity 1*554^ 
cfaosen by him as a standard. Ihe carbonic acid dmti 
r amounted to I4 grains. On adding Q39 graicu a( 
water, ihv specific gravity of the sotulion, at the (cn^ 
peraiurc of 58-3°, was 1-0401. By comparing tlui 
with a solution of nitrate of soda, of the saioc density, 
precisely in the manner described foriDcrly under luk 
phuiic acid, he found, that the salt contained io it 

amounted l" of the whole. There was an ci- 

cessofacidof about two gruns. The weight of tin 
whole was 1439 grains: The quantity of salt coate^ 

quently was —v-- =$5*142 grams. The quiDHIj— i 

of alliali was 50*05' — 14=36-05. The quantilj 
standard acid employed was £7*18 ; the whole of nbiclH 
amounted to 103*23 grains : but as only 85*142 
entered into the conipo^iion of the salt, the reatiiiiiiDi 
18'0S8 must have been pure water mixed with the m,-^ 
trie acid. Bui if 6T-I8 of standard acidcontaia IS-OU 
of water, 100 parts of the same acid must coatup 
20*92 ". ■ 

One hundred parts of standard nitric acid, therefore," 
are composed of about 13"62 parls of pure nitric acid, 
and 20*38 of water. But as Mr Kirwan has not ptft. 
red that nitrate of soda cooMios no water, perhaps tbl 



1 


P 


MtTSIC. 




233. i 


loportioii of water may be greater. He has rendered it Chip. ». . 


Ittbablc, however, that nitrate of soda cont-iins very || 


ttle water. ' 


Mr Kirwan's real acid, then, is nitric acid, of that | 


legree of strength which enters into ihe composilion of J 


Btratc of sodi. The proportion of ihJs real acid, con- 1 


Mned in nitric acid of different specific gravities, has 1 


Ken given by Mr Kirwan in the following Table : ] 




<c«Put> 




R«l 






Sp. Or.,il,. 


Atid. Sp Gnuiiy. 


Add 




1-5543 


■i-r* 


■S975 


50-7^ 




1-5295 


6P R6 


:-3925 


5n-co 






1-5183 


6B-12 


l-Mi-15 


49-2 ( 


1 




1-5010 


68-39 


1-3623 


48-?3 






1-4957 


67-65 


1-3TI5 


47-80 






1-4844 


60-02 


1-3721 


47-06 






1-4731 


66-18 


1-3071 


46-33 






J-4110 


65-45 


1-3621 


45 -Su 






I-47L17 


04-71 


1-3571 


44-80 + 






i-4eg5 


fij PS+ 


1-3521 


44-12 






1-4683 


63-24 


1-340B 


43-38 






1-407I 


ti2-U 


1-3417 


42-65 






1-4640 


61-77 


1'3J64 


41-91 






1-46J1 


61-OJ 


J-33I5 


4ri8 






1-45S2 


60-30 


1-3264 


40-44, 


■ 




1-4553 


50-56 


1-321Z 


30-71 






1-4524 


5S-S3 


1-3160 


38-S7 






1-4471 


58-09 


1-3108 


38-H4 






1-4422 


57-36 


l-305ii 


37-50 






1-4373 


56-62 


1-3U04 


36-77 






1-4324 


.55-t9 


1-2911 


36-03 






1-4275 


55-15 


1-2812 


35-30+ 






1-4222 


54-12+ 


1-2795 


3r56 




1-4171 
1-4120 


53-6S 
52-94 


I-277tf 


33-82 




1-208T ' 33-Og 




1-4089 


52-21 


l-^'iSG , 32-35 






1-4018 


51- 7 


] .500 )l-d2 




1 




J 



ts% 



ACID StTFPORTEXS. 



Book II* 
Divisioo If. 



lOO Part§ 


Real 


ICO t'iirct 


Real 


Sp. Gravity. 


Acid 


Sp. Gravity. 


Acid 


1*2464 


30-88 


1-1770 


22-06 


1 2410 


:Jo-15 


1170i 


21*32 


1'23T4 


29*41 


1*1630 


20*50 


1-2291 


20-68 


ri5di 


10*85 


l*220g 


2'4-94 


11524 


lP-12 


1*2180 


2T21-f 


1-1421 


18*48 


1-2151' 


26-47 


1-1310 


17*65+ 


1-2033 


25-74+ 


11284 


16*i)l 


1-2015 


.25-00 


1-1241 


16*17 


1-1963 


24-2(3 


11165 


15*44 


1*1911 


26-53 


1-1111 


14*70 


1*1845 


24'79 


1*1040 


13*27 



Mr Davy considers as pure acid the permaneotlj 
elastic vapour or g^s ibrmed by saturating nitrous gti 
ivith oxygen gas. Th»s gas is of a pale yellow coloar, 
and a specific gravity 2*44 times that of air. It ii not 
pure acid, containing undoubtedly a portion of nitroni 
gas. The following Table exhibits the proportion of 
this atid contained in nutric acid of different densitiei^ 
according to tire experiments of that ingenious chemist*. 



loo Pint 
Nitric acici, 
ofSp. Gr. 


True acid. 


Water. 


1-5040 


91-55 


8-45 


1-4475 


^0*39 


19*61 


1-4285 


7165 


28-35 


1-3906 


62*96 


37-04 


1-3551 


50-88 


43-12 


r3l8« 


52-03 


47-07 


1-3042 


49-04 


50-96 


J"28:U 


40-03 


53-97 


J-2090 ] 


45-27 


54-73 



• J)av\ *i RLScjrcbet^ p. 41. 






nrrxTC. 293 

trie acid is exposed to ihc action of heat, Oiip-IL 
at Ihe remperature of 248'* ", and evaporates com- Actioa of 
pleteljr without alteTation ; but when made to pass **'" 
through a red hot poicelain lube, it is decomposed, and 
convened into oxygen and azotic gasf- When cooled 
lown to — 60°, it begins lo congeal ; and when agita- 
led, u is converted into a mass of the consistence of but- 
ter t- Bui an account of the freezing points of this 
IcJd, u ascertained by Cavendish, has, been already 
^iven in a preceding part of ihis Work f . Lassone and 
Corneltc have ascertained, that when weak nitric acid 
is boiled or distilled, the weakest portion comes Grst 
over into the receiver ; but when the acid is concen- 
trated, ihe strongest portion comes Grsi over I]. 

5. Oxygen gas has no action whatever on nilric acid; 
bat all the simple combustibles decompose it, unless , 
we are to except the diamond. When poured upon 
tulphur or phosphorus^ at a high temperature, it sets 
them on fire; but at a moderate temperature it con- 
certs them slowly into acids, white nitroi;s gas is ex- 
bated. It inflames charcoal also at a high temperature, 
and even ai ihe common temperature, provided the char- 
:oaI be perfectly dry and minuiely divided •*. Hydro- 
gen gas produces no change on it at the temperature of 
[he atmosphere j but when passed along with it through 



* BnfnniDi li. 141. -) FourcTOj-, ii. S%. 

I Pwirtio;*odV»Bquelio, jfju.A r^'ar. ixU.iSi. 

I V«l. I. p. jaj. 1 A„«. p,t. ij8i. p. its. 

^ Aitotiling ID BrugnstcUi, when ■ bit at phMphorui it vrnpi up in 
•per. <lip in oitric icul, ui<l Mrnck tlnaril with i faimmcr upcn an 
■ivll. • dtionalion uk« plice /mr. A Ctim, iv. ■ ij^U'iih mc, tiow- 
mtr,At cipcttmcnt dlil iiot luccced. •• Frouu. 



^J6 ACID SUFfORT^RS* 

Book 11. 1^ red hot porcelain tube, it detonates with great vio- 
lence ; water is formed, and azotic gas evolved *• 

When this acid is poured upon oils, it sett tbem oa 
£re« This is occasioned bjr a decomposition both of 
the acid and oil. The oxjgen of the acid combinea with 
the carbon and with the hydrogen of the cfils, and at 
the same time lets out a quantity of caloric. Hence we 
see that the oxygen which enters into the oompotidoa 
of the nitric acid still contains a great deal of caloric ; 
a fact which is confirmed by a great number of other 
phenomena. The combustion of oils by this add wu 
first taken notice of by Borrichius and Slare f i but it ii 
probable that Romberg communicated it to Slare. In 
order to set fire to the fixed oila^ it must Ve mixed with 
some sulphuric acid ^ the reason of which ieema to be, 
that these oils contain wo/ir, which must be pcerioiisljr 
removed. The sulphuric acid combines with this wv 
, ter, and allows the nitric acid, or rather the oil and ni- 
tric acid together^ to act. The drying oils do not rc^ 
quire any sulphuric acid : they have beea boikd, and 
consequently deprived of all moisture. 

6. Azote has no action on nitric acid ; but muriatic 
acid decomposes it by combining with a portion of itt 
oxygen, nitrous gas and oxymuriatic gas being evolved. 
A mixture of nitric and muriatic acids was formerly 
called aqua regia ; it is now known by the name of ni. 
tro-muriatic acid. 

7. It is capable of oxidizing all the metals except 
gold, platinum %$ suid titanium. It appears, from the 



• Fourcroy , ii. 82. \ PbiL Trutit. Abr. iL 653, and tii« 663. 

t Nitre, however, acts upon platinum, as Mr Tennaat has proved. 
Fhii. Trams, 1797.— Morveau had nude the wune obtcrration in ckc Ett- 
mfnt de Cb'imh d< V AtaJimls de Dijon. 



'nperifflents of Scheffer, Bergman, Sagt, and Tillet, cK»p-ir. 
tbst nitric acid is capable of dissolving (and conse- 
qoently of oxidizing) a very minule quantity even of 
gold- 
It even sets lire to zinc, bismuth, and tin, tf it be 
poured on them in fusion, and to filings of iron if they 
be perfectly dry". 

8. Nitric add cotnbines with alkaliM, earths, xnd the 
Oxides of melals, and forms compounds which are call- 
ed mtrottt. 
' 9. Kilric acid absorbs nitrons gas with great avidity, 
/ftssDmes a yellow or brown colour, and the properly of 
jienilling dense yellow fumes. In this slate it was for- 

Iineriy known by the name ol phlogisticated nitric acid. 
The liquid at present distinguislicd in most chemical 
books by the name of nitmus acid, is nothing else than 
' this combination. Its* nature was first investigated by 
],Dr Priestley, who demonsiraied, by very decisive ex- 
[|ieriments, that it is a compound of nitric acid and ni- 
'trousgas, Thisopinion was embraced, or rather it was 
first fully developed, byMorveau-f. But the theory A com- 
of Lavoisier, which supposed the difFererce between mtrlcadj 
[.colourless and yellow nitric acid, to depend merely on "d""""' 
' the first containing k greater proportion of oxygen than 
the second, for some time drew the attention of che. 
'' mists from the real nature of the combination. Ry- 
' mood published a dissertation in 1790, to demonstrate 
^ ihe truth of the theory of Priestley and Morveau ; and 
t tiic tame thing has been done still more lately by Messrs 
Thomsoo and Davy %. 



■^ DijBD Aademituiu, and Ccnttiie. 

t. MiiM. «M. i. It. t I>*<T'* '"' 




Nitric icid being capable of absorbing very 
proportiom of nitrous gat, it is evident Uiat tb 
be a great varietj of nUro$u adds, to nae the 
phrase, differing from each other in the prof 
nitrons gas which they contain ; vnlesa we / 
confine the term to the compooad finmed bj i 
nitric acid completely with nitrons gas* 

When nitrons gaa ia placed in contact w 
acid, the acid absorbs it slowly, and acqntn 
pale yellow colour, then a bright yellow : Wt 
aidcrabk portion more of nitrous gas is absoi 
acid becomes dark orange, then olive, which 
in intensity with the gas absorbed $ then it be 
a bright green ; and lastly, when fully saturat 
comes blue green* Its volume and its volal 
increase with the quantity of gas absorbed i i 
fiilly saturated, it assumes the form of a densi 
of an exceedingly suffocating odour, and ditBcc 
densible by water. In thii state of saturation 
tinguished by Dr Priestley by the name of niil 
vtf(mr» It is of a dark red colour, and passes 
water partly without being absorbed* Theqc 
nitrous gas absorbed by nitric acid is very grc 
Priestley found, that a quantity of acid, equal i 
four pennyweights of water, absorbed iSOou 
fures of gas without being saturated *• The cc 
parts of nitrous acid, of different colours and < 
may be seen in the following Table, drawn v 
Davy, from experiments made by him on purp 
much precision f« 



« PrisitkTi L 3Sj. t IHn't JbMmK ] 





. r 




porrai Pan.. 1 






Niuit aii J. 


W„„. 


Nnrou. Ga^ 


Solid nitric acid 


1*30-1 


91-55 


8-43 





Yellow niirous 


1*502 


90-5 - 


8-3 


2 


Bright ytllow . 


l'50tt 


88-94 


8-10 


3-06 


DKkor^g... 


1-480 


S6-34 


■7-6 


5-5e 


Light obvc 


1-479 


86-O0 


T55 


6-45 


D»rk olive .... 


i-4Ti 


85-4 


1-5 


Tl 


Bright green... 


1-476 


84-B 


T44 


Tia 


Blue green.... 


1-415 


84-fl 


T4 


B-00 



The coltmr of nitric acid depends, io some measure, 
alio on the proportion of water which it contains. 
When to yellow nitric acid concentrated, a fourth part 
by weight of water is added, the colour is changed to a 
fine green ; and when equal parts of water are sdded, 
ii becomes blue *. Dr Priestley observed, that walcr 
impregnated iviili this acid in the slate of vapour be- 
came fifslhlue, then green, and lastly yellow. A greei\ 
DiCric acid became orange-coloured while hot, and re- 
tained a yellow tinge when cold. A blue actd became 
yellow on being heated in a lube hermetically sealed. 
An grange- CO loured acid, by lon^ keeping, became 
fTcen, and afterwards of a deep blue ; and when ex- 
|>OBed to air, resumed its original colour. When yel- 
i?v nitric acid is exposed to heat, the nitrous gas is 
tspellcd, and nitric acid remains behind. The gas, 
'ever, carries along with it a (junniity of acid, espe- 
I ciallyif the acid be concentrated. But nitrous acid va- 
poar is not altered in tlie least by exposure to beatf- 



itH ACID SUPPpRTXR9« 

J?^^ .":. Nitrous acid vapour is absorbed by sulphuric aci 

DiviMon IT. -r • 

^■•■^■. &t but seemingly without producing any change; for wh( 

water is poured into the naixture, the heat produced ej 

pels it in the usual form of red fumes *. The od 

nngolar circumstance attending this impregnation ii^ thi 

it disposes the sulphuric acid to crystallize f • This fiw 

first observed by Dr Priestley in 1777 1» ^^ nfterwaid 

confirmed by Mr Comette. 

It is absorbed also rapidly by nitric acid, which ss 
sumes the different colours which distinguish nitron 
acidy according to the proportion which it imbibes. 

10. Nitric acid is one of the most important instnt 

ments of analysis which the chemist possesses ; nor i 

it of inferior con^quence when considered in a politia 

or commercial view, as it forms one of the most esseo* 

Compoii. tiai ingredients of gunpowder. Its namre and compos* 

turn J 

tion accordingly have long octtfpied the attention o 



adc 



* Prieitlqr, iii. 144 f Ibid, p^ Ij6. 

t Pcrnhardt, howetrr, rclato, in 1765* that once, when he #udiai 
luif J mixtr!': uf ten p^uniis of nitre wich ui e^ual quantity of calen 
vitriol, which he had put iiito n retort, ro which fte fitted aa adofi 
bct^'S^nthe ictort and the receiver which k'nntaintd a 4''*'*'*^^^ 
ter— he ()biiervi*d a considerable quantity of a white crystal! ine nhfon 
ed in tiae adopter, wink the: liq mt aciu paucd ai nsnal into the receivi 
Thib ^aIc wa» very volatilr, smoked strongly when it wii exposed tot 
ai", ..ad exhaled a red vapou^; it bnmt to a black coal wood, 
or liiieOi aa sdlphnric acid does ; and where a piece of it fe]l« it 
ted in form of a blood-red vapour, till the whole of it disappeared. Hi 
an r<«nce of these rry^ials dissolved in water with spurting and hiMU^ 
liV ? -hat of a red hot iron dippc-l in water, and formed a green mM 
&ctd. Sonic of this salt i : ^ ; ■ * -^v ■' bottle, which was not well stO| 
ped, entirely vanished. '1 1 .: lyitals were erideodf the ssne whfc 1 
Priestky*s. See Keir*s DUtftiary. 



r^ 



liUosopherfl. Let us endeavour to trice the rarious 
tps b; which its component pans were discovered. 
Asniire ii often produced upon the surface of the 
Irtb, and never except in places which have a coramu- 
icalion wiib atmotpheric air, it waa natural to suppose 

It air, or some part of the air* entered into the com- 

litioa of nitric acid. Majow having observed, that 
hre and attnospherical air were both possessed of the 
repenjr of giving a red colour to the blood, and that 
IT was deprived of this property hjr combustion and 

ipiraiion — concluded that nitre contained that part of 
'J» air which npported a>mhuition, and viat ntcttmry 
6r rtipiration. 

Dr Hales, by applying heat to nitric acid, and what 
it osUed Walton mineral, obtained a quantity of air 
poiiuwd of singular properties. When atmospherical 
■if was let into the jar which contained tt, a reddish 
nubitl futne appeared, a quantity of air was absorbed, 
■nd ilie remainder becatr.e transparent again *, Dr 
TriTStley discovered, that this air could only be obtain- 
ed (lom nitric acid ; and therefore called it nitrout ain 
He taun<l, that when this gas was mixed with oxygen 
gai, nitric acid wa& reproduced. Hfre, then, we Snd 
thitojygen is a part of the nitric acid, and con sequent- 
1; ihai Mayow's afhrmation is veriiisd. 

Di Pfieii^ey, however, explained this fact in a difie- 
rent manner. According to tumj nitrous gas is compo- 
tedsfniiric acid and phlogiston. When oxygen is add- 
ed, it ttparatcs this plilogision, and the acid of course is 
' jirecijuUKd. This hypothesis was adopted by Mae- 



• rrgti. SUIU,, ii. 1S4. 



Bo^n. quer and Fontana ; and these three philosophen coA^j 
voured to support it with their nsual ingcnniij, li| 
there was one dinrciilty which thej were unabte ta 
moanr. When the two gases are mixed in proper] 
portions^ almost xh& whoie assumes the form of Bi|j|| 
acid ; and the small residuum (^th part), inaU prohk 
bility, or rather certainly, de{>ends on some 
hnpuritjr in the two gases. What then becomes of Ai{ 
oxygen and phlogiston ? Dr Priestley supposed thaiM 
formed carbonic acid gas; hut Mr Cavendish provi^] 
that when proper precautions arc taken, no such idi 
appears *. 

Dr Pricbtlej had procured his nitrous gas bj Smif 
ving metals in nitric acid; during the solution ofwUek 
a great deal of nitrous gas escapes. He supposed tkl 
nitrous gas* contained phlogiston, because the metal 
oxidized (and consequentlj,. according to the dica t^ 
eeived theory, must have lost phlogiston) during HslM^ 
ibation. Mr Lavoisier proved; that this supposilill 
was ill founded, by the following celebrated cipow 
ment f . To SJ45 grains of nitric acid f specific gttiilf 
1'316) he added 1104 grains of mereury.- During Ai 
aolution 273*234 cubic inches of nitrous gas werepni 
.duced. lie then distilled the salt (oxide of mercmj) 
which had been formed to dryness. As soon asitbe- 
came red hot it emitted oxygen gas,^and contiliiicdt^ 
do so till almost the whole of the liiercury was revifd; 
The quantity of oxygen emitted was 28T749 cobis 
inches. All that had" happened, therefore, during iki 
solution of the mercury, was the separation of the idi 



• Phil. Trttm, 178^^ f Mtmmf^* 177^^?* <7> 



.Jk. 



parts ; fiS(#6tls gtt% which dew off, tnd oxjgtiii ,9^JS5u ' 
di unked with the mc^al. 

f r Lavoisier concluded^ therrfore, that the Whole of 
tfhrMTs pii was derived from the nitric acid ; that 
ic IMM is composed 6f oxygen ind nittons gai ; and 
: the proportions are nearly 04 parti by we]|;ht oF 
ott gasy and S6 of oxygen gas; 
itit thcrie wa^ one difficulty which Mr Lavoistct tc* 
>wKedged he could not reftiore. The quantity of 
rgen obtained by d^cOfBpb^ing mtric add was often 
ch grater fhim what was necessary to saturate the 
rotts ga». Ml' De Morreatf attempted to account For 
If bu( wUhbift i^c^eii^. Nitrons ga$ itself wa^ 
Mently a compound r but the difficulty was to disco- 
f the ingt^ierttsw Mr Lavoisier concluded, from aiT 
periment made Hy decomposing nitre by tAeans of 
otddy that- it ^Contained azote \ and several of Dr 
iddey^s experiments led* tb the same resuh. Bui 
tar was the other ingredient ? 

Ifr Catendiih had observed^ while he was making 
Kperiments on the composition of water, that some ni- 
ie acid was foi^tned during the. combtistion of oxygen 
ad hyilh)geh gas, and that its quantity was' increased 
y adding a little atote to the two gases before the ex- * 
bsion. Hente he concluded, that the formation of 
be acid was owittg to the aecidental presence of azotic 
m ' To verify this conjecture, he passed electrical 
{ttrls through a quantity of bommon air inclosed in li 
hsstube: the air" was diminishedj and some nitric 
eid formed. He repeated the experiment, by mixihj 



« £i^. Metbmt. Ctim, Acide Nhtiqut. 

0^ 



K 



ACID lOrPOtLTEKS, 






together oxjgen uid azx>tic gat ; and fotKidt Oiat «h 
I (hc]r bore a certain proportion to each Other the^iq 
totally conT«rlibtc into nitric acid. 

Thcie experiments were tmincilnMely *e|)CMidl 
Meitsra VaD Marum and Van Treoetwyk, nd n 
nearly the lame result, 

Dr Priestley had observed MTCral years hefow thi 
cxpeiimenis were made, that Bimospherical ur mt) 
Mitnishcd by the electric ipark, am) that during the i 
tninution the infusion of tuniol became red; bat 
concluded merely thai he had precipitated the acid 
(he air. Landriani, who thought, on the cootrary,!! 
- carbomc acid gas was formed, enounced the altent 
«t lime-waisr by it ai a proof of his opiiiraii. It i 
1e refute this notion tbst Mr Cavendtsh nndertMk 
•Xperioienta. 

It cannot be doabted, then, that nilrte acid is com 
•ed of azote and oxygen f consequently nitrons gu 
«Uo composed of thesame ingredients. And atniti 
gas absotbi oxygen, even from common air, and ft 
with il nitric acid, it is evident that nitric add com 
more oxygen than nitrous gas. But it 
dilGcult to ascertain the exact pmportiens of the 
rent parts of this acid. Lavoiaicr concluded, froa 
Cxpenmciits on the decomposition of nitre by ch; 
that nitric acid is composed of oae jnrl of azMf ; 
four parts ef oxygen •. But Davy has shown 1 
(his decomposition is more complicated than had b 
aupposed ; and that Lavonier's eXperiaacnts by 
flaeaos warrant the conctssion which he drwwr fi 



* Mm. Ji Sav. Sirtit. ti.tai. 



*• GaTcnditb^ on the other htnd, concluded £rom . Chap. Il 
cperiments, that the icid which he formed, by 
iniag together aaote «nd oxygen by means of 
ioity^ is composed of one part of azote and 2*S6 
f geo. With this cesult the late -experiments of 
lavy correspond very nearly* He formed his 
ird acid by combining together known qtsantities 
rous gas and oxygen. Upon the whole, we may 
ler the proportion ascertained by Mr Cavendish 
proaching the tr-uth as nearly as possible. Nitric 
hen is ^composed 'Of 20**77 azote 

10*23 oxygen 



100*00 
idj I part of azote to 2 j- of oxygen. 



SECT. IL 



or NITROUS AGl-D^ 



\M» nitre^ which is a compound of nitric acid and 
b, is exposed to a red heat^ it yields a considerable 
ity of oxygen gas almost in a state q( purity. K 
pooess be condacted with the proper precautions 
topped ia time, the nitre still retains the properties 
leolral skit. But the acid which it contains is ob« 
ly in a difierent ^tate, since it has lost a consider* 
ptrt of its oxygen. To this new state the term 
:i add is applied. 



aee 



ejHf]r*t RfiisrfSwt f. 44. 



246 ACID ^ufreaxsas. 

Book n. Xhe experiment j ust reci ted was first ai«4e by SdiedcL 
and mentioned in his dissertation pn manganese, pub* 
lished in 1774 *. He first pointed out the diffcresei 
between nitric and nitrous acid^ but confounded oh 
trousacid with nitric acid impregnated with nitrous gat, 
His opinions were adopted by Bergmip, aod modified bj 
Lavoisier to suit his own thepry, NotwiihstamKoi 
the experiments of Priestley, which explained the ns^ 
ture of fuming nitric acid in a satisfactory manner, tin 
opinion of Lavoisier and Scheele prevailed, and the (em 
nitrous was applied to nitric acid whenever it was cai 
loured with nitrous gas. Raymond drew the attcnUoaof 
chemists to the real constitution pf fuming nitric acidii 
1706, and the same thing was done more lately br 
Messrs Davy and Thomson. It is now generally iL 
lowed, that it is merely a combination of nitric acid«n4 
nitrous gas \ and as such, its properties have been detiiU 
cd in the preceding Section. 

But the nitrous :tcid formed by exposing nitretoheit 
is undoubtedly a different substance, since nothing liks 
tlie new salt can be formed by uniting potash to fiuniBt 
nitric acid. But nil the attempts to separate the nitroui 
acid from the potash have failed. When an acid^how* 
^vcr weak, is applied, fumes of nitrous v^ponr arc iai* 
mediately disengaged. For any thing we know to tks 
contrary, nitrous acid can exist only combined witbs 
base. The genus of salts which it forma ate called »i 
trites. They are obtained by exposing the nitrates to a 
graduated heat for a certain time, and theo '•topping the 
]j>roces8. None of them have been hitherto ezamioci 
with attention except the nitrite of potash. . 



• Scheelc'i O/w*. i. 59. 



exiKratAnc. 




SECT. IH. 



OW OXtMtTRlATIC AtZlB* 



T«K composition of touriatic acid being fmpcrfectly 
■cnowfiy \ve may at presem consider it as a simple sub* 
itflance. As it differs from all other acids in having the 
^property of unitiog with oxygen and forming a new set 
-of acids which support combustion, it was thought pre- 
^fenible to separate it from the other acids, and to describe 
at along with aiiote, to which it bears a strScing analo« 
gj. When united to oxygen, it forms the two acid sup- 
porters ^led -exyrmtria^ and hypermymuriatic ; the 
{irop^rties of which we shall examine in this and the 
aocceeding Section. ^^ 

OK^muriatic acid was discovered by Scheelcin 1774, Hiiloi7« 
Airing his experiments on manganese. He gave it the 
name of depblogisfieated muriatic aci/f^ from the suppo- 
sition that it is muriatic acid deprived of phlogiston. 
T*he French chemists, after its composition had been as- 
certained, called it oxygenated muriatic acid; which un- 
wieldy appellation Kirwan has happily contracted into 
^mxymuriatic. 

The properties of this acM pointed out by Schcele 
-were so peculiar, that it immediately attracted attention, 
ttd thecaofit distinguished chemists hastened with emu- 
lation to enter upon a field ^which promised so rich a 
harvest of discoveries. Bergman, Pelletier, Berthollct, 
Hermbstadt, Morveau, Fourcroy, Scopoli, Wcstrumb, &c. 
successfully examined its properties, and ascertained its 



f4» 



ACrs StTTPORTIH. 



BookH- Kction on Other bodies ; snd more Ittelr Mr 
DIvuloB II. . , ,. , . .... 

fc— y -. Oil published ft niDst inierciUng dittcrUbon on 

acid >nd i(« combinalions *. 

prepin* 1. It may be procured by the folloiviill proccM: Pot 

'^ into a tubulated retort ■ tnijcture of tlirre puis of col 

men »alr, and one part of the black oxide of tnangui 

in powder. Place [he retort in the land bxh of a fnniu^ 

plunge it> beak intoatmall wtisr trough, and late ■ bent 

funnel into its mouth. When (he mixture )■•■ ac^iutt4 

a moderate heat, pour into it at inicrralt through 

bent funnel two parts of tutphuric acid, which ought I* 

be sotucwbat diluted with water. An effcrvcsceocc cb> 

lUes, a yellow coloured gat issues from the fciort, « bit 

may he received in large phiali fitted will) gKniA 

stoppers. 

pfopcriin. 2' Oxymuriatic acid gu is of a yellowish greco co« 

lour. Its odour is inttilctably acfid and suSbcatiag. It 

cannot be breathed -without proving fatal. The dad| 

of tbe ingenious and iudutlrious Pellcticr, whote dw 

nical labours have been so useful to ths ivoild, WU et 

casioned by his aitcntpiing to letpire ii. A coBsmny 

lion was the consequence of this attempt, which ibi 

short lime proved IUa\. When aunosplieric air cm 

uiniiig a mixture of it is breathed, it occuiou a viola 

^tod almost convulsive cough, attended with nticb pn 

ill the chcii. Thia cough usually continue* to retof 

ft intervals for a day or two, and is aocoispuuMl wil 

a copious expeciontiun. 

3> It is capable of supporting comhustioo i in aran 

{tsci even more capable ihan common air. Wbco 



t rUI. Trtmt. ites. 



oznnnitATic. 

bnming tiper is plunged into it, the flame it dintintili- ^^P- "■. 
ed, and acquires a very red colour ; a great quantity of 
smoke is emitted, and at ihe same time the taper god. 
sumes much more rapidly than in common air". The 
facility with which bodies take fire in this gas seems to 
depend on Ibe ease with which it parts with its oxy- 

4. This gas is neither altered by exposure to light 
nor to caloric. It passes unaltered through red hot 
porcelain tubes f . 

5. It does not unite readily with water. Scheele Acu'M«f 
found, that after standing 12 hours over water, ^ths of *'**'' 
the gas were absorbed : the remainder was common air, 
which no doubt had been contained in the vessel before 
the operation. Berthollet surrounded several bottles 
eontaining it with ice: as soon as the water in these 
bottles was saturated, the gas became concrete, and 
sunk lo the botiom of the vessels ; but the smallest heat 
made it rise iu bubbles, and endeavour to escape in the 
form of gas %. Westrumb observed that it became solid 
when exposed in large ves^ls to the temperature of 
40* { and that then it exhibited a kind of crystalliz*. 

' tion f. The specific gravity of water saturated with 
tbisgas, at t-V temperature of 43", is I'003 |{. From 
fierthollet's experiments, it appears that a cubic inch of 
water is capable of absorbing about 1*6 grains (French) 

I ef this acid gas. Water impregnated with this gas is 
,11y distinguished by the name of ozy muriatic acid. 
{t li<u a pale greenish yellow colour, and a suffocating 



ireMT, jtm. A CUm. r 
[Bcnlwllct.iUd. ijts. 



t Fourcrojr, ii. do. 
{ Ibid. ustU. ]»]. 



Book IL odoar like the gui$ ; its taste ii not acidf bat istriiMRnt, 

pavilion U* w •» 

<■ ^ ■■> It is usually prepared by causing the gas to pass thro* 
a succession of WoUVs bottles nearly filled with pore 
water. Light decomposes tliis add, as BerthcAlet dis* 
covered^ though it has no action on the gas* 

C It renders vegetable colours vtiiie^ and fiot red, as 
other acids do ; and the colour thus destroyed can nei* 
ther be restored by acids nor alkalies. It has the same 
effects on yellow wax« If the quantity of vegetable co» 
lours to which it is applied be sufficiently great, it is 
, found reduced to the state of common mvriatic acid. 
' ^ ' Hence it is evident, that it destroys these colours by 
coaamunicating oxygen. This property has rendered 
osyfmariatic acid a very important article in bleaching* 
, %m OxyuMiriatic acid is not altered by oxygei^gas; 
Vut a)l the sample combustibles are capable of decom- 
IKmngiu 
ActfoD of « When one measure of hydrogen gas . is mixed with 
P^H rr"* ^^"^ measures of oxjmuriatic acid*, and kept for 24 
boors in a phial closed with a ground stopper, and the 
phial is then opened under water, the whole of the ga- 
aeotts conteotsdtsappear. Hence it is obvious that they 
act upon each other : the hydrogen absorbs the oxygen 
of the acid, and is converted into water, while muriatic 
acid is evolved f . When a mixture of oxymuriatic 
acid gas and hydrogen gas is made to pass through a 
red hot porcelain t*>e, a violent detonation takes place t* 
By electricity a feeble explosion is produced* 



• T!iU pa« WM obtarncd by a wcihod to be detcflbed in the iie«t 
Section, and obvioualy conuuied a poiiion of bypcroxymiuiatlc acid 
t CuiikkhinkV,Nicholbon*f/(,:^.*. •;<;/, i8c3, v.202. 
t Vourboft u. izo. 



OXTUDRIATIO. 

V^cn tnelud sulphur is plunged into it, inSamma- ' 
lion also lakes place, and the sulphur is converted into 

' kulpburic acid * ; but cold sulplmr, though it is oiti- 

I dized by this gas, does not take firi; ill ii f. 

I When phosphorus is plunged into this gas, it intme* 

distely takes fire, bums with consideiable splendour, 
and is convened into phosphoric Rcid. This was first 

{ described by au anniiyinou& Geiman writer |, and af- 
ter wards by Weslruiub, Schmcisser, Fourcroy,and Vwi- 

I qaelio }, 

I When charcoal in fine powder is thrown into ibis gas, 

heated to about 90°, it also lakes fire, according to 
Wcsirumb i but tliis experiment has not succeeded In 

f ihe hands of other chemisis. It' we believe Professor 

' LaoipadiuE, the diamond also, when healed to Tedaciit 

I »od plunged into oxymuriatic acid gas, burns in Jt with 
great splendour ; but this experiment has aho failed in 
the hands of other chemists. 

Sulphuretcd, pbosphurcted, and carbureted hydrogen 
g&5 likewise decompose this acid; but none of them, 
except phosphureied hydcogen, produce spoutaneous 
inflammation with tt. 

I When one measure of carbureted hydrogen, from 

ether or camphor, is mixed with two measures of oxy- 
nuriatic gas, and allowed to remain for 34 hours in a 
phial closed with a ground stopper, the gases mutually 
decompose each other : water, nnuriaiic acid, carboain 
scid, and carbonic oxide, are formed. Accordinelri 

k. : ~ 

^^^^PWertnimli, LVcll'i Amal,, L Ijo. Erg. Traiul. See aUo Vol. 1. 
' p. l15.DflkuW1.rk. 




1st ACID suffoaTifti. 

When water it admitted, the whole it abtorbed except 
about 0*4S of a measure : O'>00 of this residue it ab- 
aofbed by lime-water; the rest it carbonic oxide. Whea 
there it an exceat of oxymnriatic acid, the resulting 
anbttaneet are water, muriatic acid, and carbonic ox« 
ido ^k When a mixture of two parts oxymtiriatic acid 
gas, and one part carbureted hydrogen, is fired by elec- 
tricity, charcoal is deposited, and the gas diminished ta 
0*6 of a measure; 0*5 of which are absorbed by water, 
the rest is combustible f • 

$• Oxymuriatic acid is not acted upon by either of/ 
the simple incombustibles. 
AdlMM 9* Oxymuriatic acid oxidizes all the metals without 
the aattstance of heat. Several of them even take fire 
as toon at they come into contact with the gas, as Wes- 
trumb first discovered* AU that is necessary is to throw 
a ^antity of the metal, reduced to a fine powder, into a 
vessel filled with the gas. The inflammation takes 
place immediately ; the metal is oxidized, while the 
acid, decomposed and reduced to common muriatic acid, 
coml>ines with the oxide, and forma a muriate. Arse- 
nic burnt in oxymuriatic acid gas with a blue and green 
flame; bismuth with a lively bluish flame; nickel, 
with a white flame, bordering on yellow ; cobalt, with 
s white flame, approaching to blue ; zinc, with a lively 
white flame; tin, with a feeble bluish flame ; lead, with 
s sparkling white flame ; copper and iron, with a red 
flame t« Several of the metallic sulphurets, as ctnoa- 
bat, realgar, sulphuret of antimony, take fire when 
thrown in powder into this gas. 



* Cruikihanks, Nicholion't /oi/rn a/, i3oi, v. 104. f Id« Ibid. 

4 /oarr. dr Pay* xuTti. jSj. 



omTORtATTC. 



to 



^^^H^ When ozymuriaiic acid gas and ammoniacal gai , Cli^It_ 
P vtt mixed logethcr, a rapid combusiion, attended with On unm»' 
a white flame, instanily takes place ; both the gases arc °* 
decomposed, water is formed, while azotic gas and mu- 
tifttic acid »re evolved ". The same phenomena are ap- 
parent, though in a smaller degree, when liquid ammo- 
sisis poured into the acid gas f . The same decoiopo- 
uiion takes place though both the acid and alkali be ia 
a liquid state. If four-fifihsof a glass tube be filled with 
oxymuriatic acid, and the remaining fifth with ammo- 
nia, and the tube be then inverted over water, an effer- 
vescence ensues, and azotic gas is extricated t- It was 

I bj a similar experiment that BerthoUet demonstrated 
' tbc composition of ammonia. 

11. This acid has not hitherto been combined with 
tbc alkalies, carihs, or metallic oxides ) nor have suf- 
ficient proofs been adduced that it is capable of com- 
bining with these bodies. 

12. Oxjmurialic acid gas reddens nitrous gfts, and 
converts it into nitrous acid. It produces no effect upon 
maj of the acids hitherto described, except the sulphu- 
rous and phosphorous, which it converts into sulphurio 
■nd phosphoric. 

13. When muriatic acid is mixed with nitric acid, Aquawr*- 
the compound has precisely the smell and the qualities 

«f oxymuitatic. This mixture of the two acids was 

formerly called a^a re^a ,- but at present it is usualljr 

denominated nitre muriatic add. It is first mentioned 

^^^^UC Hollandus, and seems to have been knowa be- 

^^^^H*Fo<iren7, ^m. A Cbim. i«. 155. 

II f WeRiuiDb, Crrll'>^M;»,i t6i. EngtuhTrinil 
I Jmr. it r£ah Ftlflnl*. 



•^W* fort fb« mmatic acid itself. It was preptred hj poaU 
%■ y I I lOfr nitilc mcid on common salt. The nttric mcid de^ 
eompofet the salt, and part of it unites with the ttorbk 
tie acM thos aet at liberty* At sooo aa theie two aeidi 
an mixed they begin to aet upon each other. Hk 
flwrislic acid decomposer part of the nitric, comlmict 
wifb itB OKjgen, and i» that partly coirrerted into ossy- 
srarfatic acid. Hence the tuffbcating odour of that 
aicid whkh the mitture exhales. The nitroot ga% thni 
aai at liberty^ is absorbed by the undecdiiipoaed nitric 
atid> and conTertt it into nitroua acid. When tbes6 
amtual combinationt are completed, the action of the 
lw» aeida on each other ceases. Thus nitro^mnriati^ 
acid it a mixture or combination of nitrous attd^ nniri« 
arte acid) and axymuriatic add *. 
Sappoted Mr Lambt some time ago f announced, that when 

^fanirUtic '^^^ i* acted upeu by sttlphureted hydrogen gas, a suki 
^^ stance it produced which possesses all the properties of 

Mymuriate of iron (oxymuriatic acid combined with 
iron)* In a solution of this gas in distilled water, he 
digested iron filings^ previously purified by repeated 
washings with distilled water. The bottle was filled 
with the solution, and corked. The iron was presently 
acted upon ; numerous bubbles arose, which droVe the 
cork out of the bottle ; they were strongly inflammable^ 
and'probably therefore pure hydrogen gas. The liquor 
gradually lost its odour of sulphufefed hydrogen gas^ 
and after some days smelled very much like stagnant 
rain-water* As the bubbles ceased to be produced, it 
recovered its transparency. On evaporating a small 



a Fourcroy, ii. 107. t NkudHiUr Mm, v. 194. 



otTHtmiATia. 

qoaatity of this solution in a waTcfi-glass to drynest, a 
bitter deliquescent sali was left behind. On this salt a 
Utile sulpbuHc acid was drof^cd, and paper moistened 
WtUi sinnionia was iield over tlie glass ; white vapoura 
were imniedialely formed over the glass v and conw 
qucDtlj- some volatile acid was separaied by the sulphu- 
ric acid. Mr Lambe evaporated about eight ounce- 
neasarcsof the same liquar, and, as befare, dropped a 
little sulptiaric acid on the residuum i a strong cffer- 
▼escence was excited, very pungent acid fumes arosv, 
which, from their smell, were readily known to be imk 
riatic. The same truth was tMabliihed beyond adoobf, 
by holdiag a bit of paper, moistened wilh water, which 
made the rapours visible in the form of a grey smoke; 
a distinguishing charuclcristie, as Bergman has obser-* 
Tcd, of the muriatic acid. When manganese and mer- 
cury were dissolved in sulphureled hydrogen gas, the 
salts formed gave the same unequiTocal marks of the 
presence of muriatic acid. 

This experiment of Mr Lambr baa been lately re- 
peated with every possible precaution by Vauquelitr^ 
and rIso by Giiyion Mon'i-au and Bouillon Lagrange; 
but these clicmists did not succeed in obtaining a par- 
ticle of oXy muriate cf iron *. We must conclude, then, 
that in ihc experiment of Mr Lambe, muriatic acid 
UQSt hare insinuated itself into his solalion by soma 
wiknown channel. A fact meniioned by BerthoUet 
may perhaps coniribtile something lo explain this insi-> 
nuation^ aud may also suggest a valuable hint towards 
ihc invcstigaiion ui the real coniponeut parts of this ob- 



JLCID SOrrOKTCM. 

ttintte add. He converted a quantity of iron into filtop 
with all possible care. The lilingi, when waxbtd witk 
water, gave no marks of containing muriatic acid ; b«t 
after being exposed for some days to the air, ihey fu. 
nishcd, wben again washed, evident traces o£ ilie 
tencc of mariatic acid *• 

14. From the action of oxymurladc add on eawbui 
•trnuriuic tiblcs, above described, and the compounds prodticcd b 
it, no doubt can be entertained that it is a compound i 
muriatic acid and oxjgen. This was Arst dcmonstratt 
bj Berlholtet, by a great number of ingenious and 
live experiments. 

He attempted also to ascertain the proportion of 
constituent pnrts. For this purpose he saturated 50 i 
bic inches (French} of water with oxymuriatJc adi, 
andezposed the liquid for some days to the light of tbftl 
■un. The oxygen gas disengaged amounted to IS 
cubic inchei (French) or 8 grains. The muriatic adj 
which remained in the liquid amounted to 65 gntni^ 
Hence it follows, thai oxymunatic acid is composed tt 
O^ parts muriatic acid and B parts oxygen, or of aboal 

SD mitt'.,ticactd 

1 1 oxygen 

10 

Bat this method, though exceedingly simplo and inp& 
nious, was scarcely susceptible of precision. Thr nit 
lysis of Chenevix, made in a diScrcnt way, dcscivci 
more confidence. Tliis celebrated chenit&t cauied i 



• Amk, /( Cllm. luvii. 194,— SlmiUr facti 
Vtimbj MtrgniT. 



OXTMURZATIC. fi5«t 

tnt cf oxvmuriatic acid gas to pass through a dilu- ,^hip.J[I« 
olution of potash in water, till it contained an ex- 
of acid. He then evapol'ated to dryness, and pro- 
id a .saline mass containing all the potash, and the 
muriatic ac:d. But uh^n oxjmuriatic acid is made 
ct upon potash in this manner, it divides itself into 
i portions ; one portion consists of common muriatic 
I, the other contains all the oxjgep, and is therefore 
he state of hjperoxy muriatic acid. The potash in 
drj salt was therefore partly comt)ined with muria- 
acid, and partly with hyperoxy muriatic acid. Ni- 
e of silver precipitates the first of these adds from 
solutions, but not the second. Hence an easy me* 
I of ascertaining the relative proportion of these two 
s in a given quantity of salt presented itself. Ac- 
ingly Mr Chenevix ascertained, that in 100 parts 
le dry salt, 84 consisted of 5C*12 parts of potash 
bined with 21*88 of muriatic acid, and 10 of B*8 
^tash combined with ) 2*^ of hyperoxy muriatic acidi 
he had ascertained, by a method to be described in 
next section, that 12'2 parts of hyperoxy muriatic 
contained 9 parts of oxygen and 3'2 of muriatic 
. Tlierefore 2TS8 + 3*2 = 31*08 muriatic acid ; 
9 parte of oxyoen forip 40*08 of oxy muriatic acid. 
ice it follows, that oxymuriatic acid is composed of 

■ 

71*3 muriatic acid 
j22'5 oxygen 



100 
5. Thoitgh oxymuriatic acid has hitherto l)een pla- ^Jot 
among acids by chemists, it does not possess a single ^^^^« 
lerty which characterises that class of bodies. Its 
is not acid but astringent j it does not convtrt ve** 



an 



ACID SOrPORTBRS. 

gctable blues to red, but destrojrs them ; it coinbiiwt* 
very iparingly witli water, and is not capable of DeG< 
iializing alkalies, earths, or coetalltc oxides. It oujbi 
therefore to be placed among the oxides rather than tbe 
acida. But Scheele, the original discoverer of it, wu 
induced, from the theory which then prevailed, to cod- 
sider it as merely muriatic acid deprived of phlogiitaan 
and after the mistake was discovered, the tlieory of] 
voisier respecling the acid principle, which thi 
fashionable, was considered as a sufficient reason (m 
continuing it in its phce among acids in spite of ih 
properties. It must be confessed, however, that ladi 
arbitrary arrangements are no small impediments to the 
progress of the science. 



OF HTFEROXTHUKIATIC ACID. 

TVc existence of ihb acid was first suspected by BIr 
SerlhoUet, though he satisfied himself with little 
iban strong analogy. It has been lately put out ef 
doubt by the experiments of Mr Chenevix. 

1. If a solution of potash in six times its weight rf 
water be put into a Wolfe's bottle, and a stream otoTf. 
muriatic acid gas be made to pass through it in dM 
usual way till the potash is saturated, crystals in I 
form of fine white scales are deposited in considenl 
quantity. These crystals have received the nunc 
hyptrtDtygtnisud muriate of potatb. They possm ittf 



HrP£R0XTrMORIATlC. 

Tioas uid important propwties. If the liquid from 
which thii's;iitis deposited be evaporaled lo dryness, 
■nother salt will be obtained, composed af muriatic acid 
9S»A fotoih. These facis were all discovered by Ber- 
IhioUei. He coacluded from them, ihat theoxymunaiic 
«6id had been decomposed during ihe process ; [hat one 
portion of it lost the whole of its oxygen, and was re- 
duced to the Slate of muriatic acid, while another portion 
COtnbifled with an additional dose of oxygen, and was 

'crted into hypcroxymuriatic acid. Hence tbc appel- 
latioa of the salt which contained this last acid. 

. Thistheory of Berlhollct was very plansible; and 
it induced the greater number of chemiMs to believe 
that Ihe substance to which hyperoxy muriate of potash 
owes its peculiar properties, differs fromoxymiiriatic a^ 
acid by containing an additional dose of oxygen. But 
the opinion remained destitute of sufficient proof, till 
Chenevix published his important dissenaUon on 
the subject in 1802. Mr Cheuevix exposed 100 grains 
of hyperosy muriate of potash to the heat of a lamp ; it 
lost 2*5 pads of its weight, which he ascertained lo be 
water. When heated to redness, a violent efieives- 
eence took place, and 113-5 cubic inches of oxygen 
gas, or 3S-3 grains, were extricated. The salt which 
reauuned in the retort amounted lo 53-5 grains, and 
Gtc grains had been volatilized during the process". 
Hence it follows, that hyperoxymurtate of potash is 
composed of 



' It hid bcea long known that tlu) nlinc re«duc u a 
psmh Mil BturiMJc Mid, 

R3 



265 ACrD SirrPO&TERS. 

Book If. 2*3 water 

^vision Tf, 

38*3 oxygen 



58*5 muriate of potaUi 



99-3 
But Mr Chenevix ascertained^ that the mariatic aeidrc^r 
maining in this saline residue amounted to 20 gruni. 
Therefore 3S*3 parts of oxygen, and 20 parts of morit- 
lic acid, constitute 58' i parts of the acid which exists is 
byperojjmuriate of potash. That acid of course is com* 
posed of ahout • • • , .^ • 66 oxygen 

84 muriatic acid 



100 
The acid which constitutes a part of hyperoilymiiritte 
of potash contains, we see, nearly nine times as mach 
oxygen as exists in oxy muriatic acid. Thus the tbcocj 
of Berthollet is confirmed in the fullest manner. Ws 
see that muriatic acid combines with two doses of oxy- 
gen ; with the first dose it constitutes oxy muriatic td(f, 
with the second the acid that exists in hyperoxjmuriite 
of potash, which has been cMed Jtjypero9cymuriatic mq^* 

Oxymuriatic acid contains •0*22 oxygen 

Ily peroxymnriatic acid ••••«••• 0*66 
Hence it follows, tbat 

J^Iuriatic Oxyrtiur. 

acid Oxyft^rn. ac:d. 

1-00 + O-og = r:,9 Oxyiccn. Hn>erQxjmvbdcieid. 

1*29 + 1*62 = 2*91 

Cannot be 3. But though the peculiar nature of hyperoxyino« 

obtaineJ •.- riatic acid hw been thus demonstrated^ all attempts to 

procure it in a separate state have hitherto failed. Its 

properties therefore are but imperfectly known. Fran 

the amazing ener^ with which hyperoxymariatt sf 



H7F£R0XTMimiATIC. 201 

[^tash acts upon combustible bodies^ it is obvious that Chap. n. 
it possesses in perfection the property of supporting 
comlDiistion. It combines also with alkalies, earths, and 
metallic oxides, and forms salts of a very peculiar na- 
ttirc, wliich we shall afterwards examine, Mr Chene- 
vlx has rendered it probable, that it converts vegetable 
blues into red. It cannot be doubted that it combines 
with water^ Several jAenoroena indicate, that ivhen 
pure it assumes the gaseous state. 

4. When sulphuric =acid is poured upon hyperoxy- Action ^ 
genized muriate of potash, a violent decrepitation takes *^^ '^ 
place^ and sometimes a flash of Tight is visible. The 
sulphuric acid in this xrase combines with the potash, 
and disengages the hjperoxymuriatic acid. This last 
acid rises in the state of a heavy Tapour of a greenish 
yellow colour; its smeH has some resemblance to that 
of nitrous gas, but peculiarly fetid : it is compared by 
Mr Chenevix to the odour emitted by brick kilns, mixed 
Avith that of nitrous gas. At the bottom of this vapour 
is a bright orange- coloured liquid, consisting of the 
sulphuric acid, the potash, and a portion of the hyper- 
oxymuriatic acid. But the acid thus separated is not 
pure, being partly decomposed by the process, and be- 
ing mixed with a portion of sulphuric acid. If we at- 
tempt to separate the hjperoxymuriatic acid by distilla- 
tion, the moment the mixture is heated to about 120^, 
a violent explosion tak^s place, which breaks the vessels 
in pieces. This seems to be owing to the rapidity with 
"which the acid is decomposed by a moderate heat *. 
Nitric acid produces nearly the same effects as the sul* 
{>huric« 



« iloylr, Mamhiittr M^wuirttf, aaa^Chcorfiz. PliL Tr^m, iSoi. 



i{i2 ACID SUrFOKT£llS. 



Division [I. 



5. When muriatic ncid is poured upon the salt, a 
violent effervescence takes place, and gas is emitted a- 
gcid?"^**'"^ bundantly, which has the smell and colour of ozjimi- 
riaticf acidy but is much more rapidly absorbed by wa» 
ter. This process was first pointed out by Mr Craib* 
shanks. He obtained in this manner the gas which he 
employed in his experiments on carbonic o;dde. When 
two measures of hydrogen gas are mixed with 2*3 
measures of gas procured in this manner, Mr Crnik- 
shanks found that the mixture explodes feebly with the 
electric spark, and is totally converted into water and 
muriatic acid. But two measures of hydrogen gas re* 
quire one measure of oxygen gas to convert them into 
water. Hence Mr Cruikshanks infers, that 2*9 parts 
of tlie gas procured according to his process, contain ooe 
part of oxygen and 1*3 of muriatic acid ; which gives 

as its component parts, 56*5 muriatic acid 

43*5 oxygen 

100*0* 
This shows us that the gas extricated from the salt bj 
muriatic acid is not pure hy per oxy muriatic acid. Hr 
Chcncvix supposes that it is a mixture of that acid and 
Oxymuriatic acid gas: a portion of the first acid being 
decomposed by the muriatic acid, with which it 
comes in contact at the moment of its disengagemcBt. 
But there are some reasons to question this opinion. 
When water, impregnated with oxymuriatic acid gai^ 
obtained by Cruikshank's method, is mixed with li- 
quid ammonia, scarcely any gas is extricated. The tw^ 
bodies combine and form a salt. 



* Nicholson *9 Jcttmal^ i8os, v. 20^. 



AA5EMIC. 

Mn^ siiU leniainE to be done before ihc properties 
tthis interesting acid be folly de\t]oped, Mr Che- 
ix has ascertaioed, thai it is always formed when ni- 
muriatic acid is boiled upon platinum, and likewse 
BD oxide of titanium is precipitated by potash from 
acid. 



OF ARSENIC ACID. 



iXGy us we have seen formerly, is capable of 
smbiniDg witb two doses of oxygen; and both the 
lOEOpounds which it forms with that body possess acid 
ptoperties. The first, distinguished by Fourcroy by the 
tUDC oi arienioui acid, but more usually denominated 
vbittaxidio/tattnic, has been already described*. The 
lecimd, called artenic add, was discovered by Scheeic 
• 1115 ft ^ii^ 't^ most remarkable properties investi> 
ptied. Pelletier afterwards published a valuable dis- 
Krtxtion on il. And more lately its properties and 
tODsUtnent parts have been more completely invcstiga* 
led by Proust and Bucholz |. 

J. Arsenic acid is usually prepared by the process Ptepan- 
pointed out by Scheele. Three parts of white oxide of 
■Tsenic arc dissolved in seven pans of muriatic acid, and 
Uw sohiliot) is mixed with five parts of nitric acid, and 
distilled to dryness. What remains is arsenic acid. But 
tbis method has been considerably improved by Bu. 
cholz. His method is as follows. Mix in a retort one 



, * Sec VoL L p. 31}. 
t Jin-.^Ciaa. iv.J. 



904 



AC|0 80rrORTKM* 



Book IT. 
DivitioD (T. 



ffopartieii 



^f finn of 
Witter. 



Of simple 



ptrt of muriatic acid of the specific grmvity 1*2, foot 
parts of the white oxide of arsenic, and 12 parts of ni- 
tric acid of the specific gravity 1*25* Boil the mixtnit 
till the oxide disappear and nitrous gas ceases to be dis. 
engaged. I hen evaporate to dryness, and expose die 
mass ior a few minutes to a low red heat. What re- 
mains after this is solid arsenic acid. 

2. Arsenic acid, thus prepared, is a white solid man, 
nearly tasteless. Its speci6c gravity is 3*301. It is 
very fixed. When hoated strongly, it melts and re. 
mains transparent, and is converted into a glass, which 
acts powerfully on the vessel in which the experimcat 
is performed. This glass attracts moisture from the 
air. When the heat is very strong, the acid gives oot 
a little oxygen gas, and is at the same time partly oon- 
verted into white oxide. 

3. It d'ssolvcs vfrry slowly in sJx parts of cold in- 
ter ; but two parts of boiling water dissolve it almost 
instantl}', and it remains in a stnte of solution even tho* 
a considerable portion of that water be evaporated. 
With half its weight of water it has a syrupy consin* 
e:icy ; and by farther evaporation it deposites crystals 
in grains *. Its taste, when liquid, is acid, caustic, sod 
metallic. 

4. Oxygen has no action whatever on this acid; nci« 
ther is it affected by exj)osiire to the open air. 

5. The simple combustibles decompose it by the as« 
sistance of heat : And in these cases, as we learn from 
the experiments ot Scheele and of the Dijon Academi- 
cians, combustion sometimes takes place ; a proof that 
arsenic acid is a supporter of combustion. 



^ Bucholz, Jour, di Cbim, iv. 5. 



' AKSEVIC. M5 

O. The simple incombusdbles do not appear to pro« ^ Chap . If, 
duce any alteration on it. 

7. Several of the metals decompose it when assisted 
by heat. It does not act upon gold^ platinum, silver, 
mercury. It oxidizes copper, iron, lead, tin, zinc, bis- 
muth, antimony, cobalt, nickel, manganese, and arsenic, 
and in a strong heat mercury and silver. 

8. It combines with alkalies, earths, and several of 
the metallic oxides, and forms compounds which have * 
been called arseniates, 

9. From the way in la'hich this acid is formed, it Compoil. 

. '. . tioa. 

cannot be doobted that it is composed of the white ox- 
ide of arsenic and oxygen. Nor is it very difficult to 
ascertain the proportion of these constituent parts ; for 
the oxygen must be equivalent td the increase of weight 
which the oxide experiences during its acidification. 
From the experiments of Proust we learn, that 'this 
augmentation of weight amounts to 0*15 parts: Bucholz 
found it 0*16 ; a degree of coincidence as great as can 
be expected in experiments of that delicate nature; 
Hence it follows that arsenic acid is composed of about 

86'5 white oxide of arsenic 

13" 5 oxygen 

100*0 

But the oxide of arsenic contains nearly 0*25 of oxygen. 
This gives us arsenic acid composed of about 

65 arsenic 

35 oxygen 

JOO 

It is only the second dose of oxygen, amounting to 
}3*5 parts, which gives this acid the property of sup« 




J'^} ";, porting combusiii 
I- ■V— ■ ' strongly hestled. 



ACID SDrrOKTMS. 

a, and of emitting oxygca gu wbn 



SECT. VI, 

OF TUNGSTIC ACID. 



J/he substance called tungttic aeid by Schcele ai 
Bergman was discovered by Scheele in 1I81. Thit 
philosopher obtained it from tungitate of litnr by tnat. 
ing it with nitric acid and ammonia aliernatcly. Tbe 
acid dissolves the lime, and the ammonia combioa 
with the tungstic acid. Tlic ammoniacal loliuioa, 
when saiuraicd with nitric or muriatic acid, deposiiei 
a while powder, which is the lungUic aeid of Scheele. 

This powder has an acid taste, it reddens vegctablt 
blues, and is soluble in 20 parts of boiling water. Tbe 
Qe Luyarts have deroonsirated, that ibis pretended add 
is a compound of yellow oxide of tungsten, the alkali 
employed lo dissolve it, and the acid used to precipi< 
tatc it. Thus, when prepared according to the above 
described process, il is a compound of yellow oxide, 
ammonia, and nitric acid. Their conclusions have beca 
more lately confirmed by the experiments of Vauaiulia 
4nd Hecht. This substance must therefore be erated 
from the class of acids, and placed among the salts. 

The real acid of tungsten is a yellow powder; the 
method of procuring which, and its properties, have 
been already described under tbe denomination of ytU 



t^itidttf tiugtlm*. It ought rallier, as Vauquc- 
aod Hecht have properly remarked, to be classed 
noDg the osides than the acids ; for il is insoluble in 
rater, tasteless, and has no cfTccl on vegetable blues. 
It^ces with the acids indeed in the property of com- 
itiiog with alkalies and earths, and perhaps also with 
metallic oxides, and forming with them salts, 
riiich have been denominated lungjtata ; but several 
tbcr metallic oxides, those of lead, silver, aod gold, 
^ instance, possess the same property. These oxides 
^efore may be called acids wiih as much propriety u 
yellow oxide of tungsten. 



SECT. VII, 



OF UOLTBDIC ACiq. 



ploLSBDIC acid was discovered by Scheele in ma, Hu»n- 
luring his experiments on the sulphurec of molybde- 
bumi and its most remarkable properties ascertained. 
Scarcely any farther addition was made to our know- 
ledge of it, till Mr Hatchett published his dissertation 
•n the molybdale of lead, in the Philosophical Tran- 
factions for 1796. That ingenious chemist examined, 
with his usual precision, such of its properties as were 
Connected with this subject. In the summer of 1S05, 
pan elaborate dissertation ou molybdenum was publish- 
■4f in the 4th volume of Gchlcn's Journal, by Bucholz, 



tiom 



208 ACID SOrFORTERl. 

Bock II. who did not neglect to ascertain the constitaents tad 
the mode of procuring this acid. To Schecle, Hatcbett, 
and Bucholzy we owe most of the facts respecting mo* 
Ijbdic acid at present known. 

From the experiments of Bucholz it appears, thtt 
two of the combinations of molybdenum and oxygea 
are soluble in water ; namely, the b/tte oxide and the 
peroxide. If the first be capable of neu^raliiing alka- 
lies, it will belong to the class of acids, and may be 
distineuished by the name of tnolyhdous acid ; but its 
acid properties have not been ascertained. The prr- 
oxide, however, neutralizes alkalies. It has been al- 
ways distinguished by the name of molybdic acid. 
Prepan- • It is usually prepared from roolybdena, or native 
sulphuret of molybdenum, by the process pointed out 
by Scheele« Reduce the mineral to powder, and distil 
off it nitric acid, or rather a mixture of nitric and muri- 
atic acids, till the whole is converted into a white mass. 
Edulcorate this mass with water to carry off the sul- 
phuric acid formed, and the remains of the other acidk 
It 18 tiow molydic acid tolerably pure. 

Another method has been lately pointed out by Bu- 
cholz. Reduce the mineral to a fine powder, and ex- 
pose it to heat in an open crucible, stirring it with an 
iron rod till the whole assumes an ash-grey colour. 
The heat is to be at first a strong red, but gradually 
lowered as the roasting advances, to prevent the pow- 
der from cohering, which would render the completion 
of the process very difficult. By this roasting the sulphur 
is dissipated, and a considerable poilion of the metal 
acidified. Reduce the mass to powder, and digest it % 
sufficient time in water holding soda or ammonia in 
solution ^ the molybdic acid is taLcn up, and combines 



MOLTfiBIC. i269 

m 

with the alkali, while the iinpuriues remain behind, ^y* y* ^ 
t^et the solution remain cocked up till it has become 
clear, decant it off from the sediment if anj thing has 
subsided, and pour into it some muriatic acid. The 
moljbdic acid precipitates in the state of a fine white 
powder, and may be easily separated and edulcorated *• 

Moljbdic acid, thus prepared, is a white powder, the Propcrtiei^ 
specific gravity of which is 3*460. When heated in a 
dose vessel it melts and crystallizes ; but in an open 
vessel it sublimes in a white smoke, which attaches it* 
self to cold bodies, and assumes the form of brilliant 
yellow scales. 

It is soluble in 960 parts of boiling water. The so- 
lution is pale yellow ; it has no taste, but reddens lit- 
mus paper. The molybdic acid is .precipitated from 
this solution by sulphuric, nitric, and muriatic acids f. 

Molybdic acid is not affected by oxygen gas ; hut it 
is decomposed by sulphur and charcoal, and several of 
the metals. When heated withtlie protoxide of molyb- 
denum, the mixture is converted into blue oxide X* 

It combines with alkalies, earths, and several metal- 
lic oxides, and forms salts known by the name of mo^ 
lybdates. 

Sulphuric acid dissolves molybdic acid when assisted 
by beat. The solution is colourless while hot ; but 
when cold it assumes a deep blue colour, which is 
heightened by saturating the solution with soda. When 
this sulphuric acid solution is heated strongly, the suU 
phuric acid is evaporated, and molybdic acid remains. 
Muriatic acid also' dissolves it. The solution is of a 



• Gehlen'i Jour. iv. 604. 

f Hatchect, PbiL I rant, Ixxxvf. 313. 

I Bnchois, Gthien, it. 626., 



ACID SUPPOKTEKS. 

pale yellowish green colour ; but it becomes blue win 
- saturated with potnsh. Nitric acid does not ^n' 
this acid •, 

This acid, when combined with potash, forms a 
lourless salt. 

Miiced wiih filings of tin and muriatic acid, it ii 
dialcly becomes blue, and precipitates flakes of t1 
same colour, which disappear after some time, if an c 
cess of muriatic acid has been added, and the li^noi 
assumes a brownish colour. 

With the solution of nitrate of lead it forms a wliiic 
precipitate, soluble in niiric acid. 

When mixed with a little alcohol and nitric add, ft 
does not change its colour. 

With a solution of nitrate of mercury, or of ninit 
of silver, it gives a white flaky precipitate. 

With the nitrate of copper it forms a greenisb preel' 
pttate. 

With solutions of sulphate of zinc, muriate of bis* 
muth, muriate of antimony, nitrate of nickel, murittei 
of gold and platinum, it produces white precipilatci 
when these solutions do not contain an excess of acid. 

When mellcd with borax, it gives it a bluish colonr. 

Paper dipt in this acid becomes in the sun (^a b 
liful blue colour f. 

From the experiments of fiuchoix we learn, t!bit 
when 100 grains of molybdenum are digested with ni. 
trie acid till they are converted into molybdic acid, aad 
then dried, they now weigh abom 140 grains, HcnceU 
follows, that molybdic acid is composed of about IDO 



• Haldirtt, Ptil. fr—r. Inrw 3J3. t V»uquelui, H»l. Maj. I. iSt. 



CHROMK 



,~ metal and 49 oxygen ; or very nearly two parts Ch» p.n. 
ital to one oxygen ; orfitr cent, of aboiit t 

61 molybdenum 

33 a:^gen 



or cmtoMic acid. 



L/HRONIC ACID, discovered lately by Vauquelin^ has p«|im>- 
oolj been found, in any quantity, tn tlie red lead ore 
of Siberia, and in chromate of iron. Its properties 
have been investigated by Vauquelin and Mussin 
Aischkin. 

It may be obtained by boiling the red lead ore with 
carbonate of soda, decanting ofT the fluid solution, and 
saturatiof it with one of the mineral acids ; a red pow- 
der precipitates, which is chromic acid. 

Chromic acid, thus obtained, is a red or orange-yel- ^"V^"- 
low powder, of an acrid and strongly metallic taste. It 
is soluble in water, and crystallizea in the form of elon- 
gated prisms of a ruby colour. 

When heated it gives out oxygen gas, and is conven- 
ed into green oxide of chromium. 

When mixed with filings of tin and the muriatic acid, 
it becomes at first yellowish brown, and afterwards as- 
sumes a bcantifnl green colour. 

■ Cchkn'i /«r. iT. GiS< 



StnCt ACID SUPPORTERS. 

Book IT. When mixed with a little alcohol and nitric acid, it 

immediately assumes a bluish green colour, which pre- 
serves the snme shade even lifter desiccation. £iher 
alone gives it the same colour. 

With a solution of nitrate of mercurj, it gives a pre- 
cipitate of a dark cinnabar colour. 

With a solution of nitrate of silver, it gives a precis 
pitate which, the moment it it formed, appears of a 
beautiful carmine colour, but becomes purple bj expo- 
sure to the light. This combination, exposed to tbe 
heat of the blowpipe, melts before the charcoal is in. 
flamed. It assumes a bUckish and metallic appearance. 
If it be then pulverised, the powder is still purple ; but 
after the blue flame. of the lamp is brought ia coniaclf 
with this matter, it assumes a green colour, and rtied* 
ver appears in globules disseminated throughout iti 
substance. 

With nitrate of copper, it gives a chesnut red preci* 
pitate. 

With the solutions of sulphate of zinc, muriate of 
bismuth, muriate of antimony, nitrate of nickel, aodi 
muriate of platinnm, ic products yellowish precipitates 
when these solutions do not contain excess of acid. 
With muriate of gold it produces a greenish precipitate* 

When melted with borax or glass, it communicates 
to them a beautiful emerald green colour. 

Paper impregnated with chromic acid assumes in the 
light a greenish colour. 

When mixed with muriatic acid, the mixture is ca- 
pable of dissolving gold like aqua regia : when this 
mixture of the two acids is distilled, oxymuriatic acid 
is disengaged, and the liquor assumes a very beautiful 
green colour. 



COLOHIie. 

Sulpboric acid, wbile cold, produces no effect apon 
; but when warmed, it makes it assuine a bluish 
colour, probably bj favouring the diseagagemcDt 
oxygen. 

Wbca tbis acid is heated along with charcoal, it is 
pcdnccd to the metal called thromium. 



or coluhsic acis. 



XHts metallic acid has hitherto been delected in one Pr«wn. 
'men only, in which it is combined with the oxide t*™- 
iron. Mr Hatchett, lo whom we owe the discovery 
Its peculiar properties, separated it from the iron by 
[dsing it with potash. The alkali combined with a. 
portion of the acid which was separated by water. Mu- 
lic xcid dissolved the oxide of irou thus deprived of 
acid \ and the ore, after this treatment, yielded ao 
■ddidoDal dose of acid when fused with potash. By tc* 
peuing this process, the whole of ihe acid was com- 
bined with potash : the solution was limpid. Nitric 
ftdd precipitated the columbic acid from the potash in 
the slate of while flakes. 

. The acid thus obtained is of a pure white colour, pf^mics 
not remaikably heavy. It has scarcely any taste. 
It is insoluble in water, but gives a red colour to paper 
stained with litmus- When exposed to a litroog hea^ 
it does not melt, but loses its lustre. 

2. Sulphuric acid dissolves il, uiti toinis a trampa* 
rent colourless solution : But when the uquid is dilated 
Fol. 11. 3 



3T4 



ACID lUfVORTERS. 



Bocdc IT. ^ith water, it liecomcB milky : a white 'precipitmtc filk 

< y f which becomes lavender blue ; and when dry, htow^ 

ith grey. It it aemitransparent, and breaka with a li. 

treous fracture. This substance is a compoond of laL 

phuric and columbic acids. 

3. Nitric acid does not dissolve this add ; nor doeiit 
produce any change on its properties. 

4. Muriatic aeid dissolves ii wbsn assisted by heat 
The solution does not become muddy when diluted with 
water. When evapprated to dryness, it leaves a pik 
yellow substance difficultly soluble in muriatic acid. 

i. Potash and ioda coddiine readily with colnmhic 
acid. With potash this acid forms a glittering scslj 
•salt likQ boracic acid. It coatains a slight cxoass of ^ 
kali; has an acrid disagreeable fliavovc; «laeS'iMtd» 
.solve readily in cold water ; hot wheh dissolved^ Ik 
Tfldlution is perfect and permanent. Nitric acid ftmfi* 
'fates the columbic acid. But ccdumbic «cid ia eapsbfc 
of expelling carbonic acid from potash *• 

The other properties of this add retaaia to be iami 
tigated. 



* Hatchctt, FhH. Trms. iSoa. 



KlS 






N 




CLASS irr. 

COMBUSTIBLE ACIDS. 



iHE adds belonging to this class were fgrmerlf disiin- 
lished by tlic appellation o^ veritable and animai ticidif 
almost the whole of tliem are piocured from the 
imal Mid vegetable kingdom. They differ essentially 
im the otbcT two classes of acidi in aeveral particulars. 
1. If they be combined with potash and distilled, ^ 
ey are completely decomposed, charcoal is usually c> 
roWed, and a considerable quantity of heavy infiam- 
: atf extricated -, whereas no combustible substance 
: procured by exposing the other acids to heat *. 
All of [hem contain at least two simple combust 
Ibic substances as a base; whereas the others never con- 
thau one. These two substances are always 
tirhon sod hydrogen. Some of these acids contain like- 
■\iit azote, over and above the two simple combus- 
ibles. Oxygen also usually enters into their composi- 
in considerable quantiiyt but not perhaps always. 
fa them, therefore, the theory of Lavoisier, respecting 



> Svlphuroui uid phoiphotoua u'tit cxcepCei], yMA etiiic lulphur 
I {ilwiftiumcd bjrdrogcn when (ipoicd lo bcii. 
S2 



I 



2<t0 



SOIUU8TIBLE ACIDS « 



**™' "-ji^ the necessitjr of oxygen as the acidifying piiociplE, dca | 
t.— ^— t not strictly apply. 

3. They do not seem capable of combining withdl 
ferent proportions of oxygen. Whenever the i^ui 
of oxygen is changed, (he proportion of the o 
Stituents changes a,Uo. Of course the termitm»^ 
their names ought not to indicate the proportton of cu 
gen which they contain ; but should, if posiible, be !» 
dependent of that proportion altogether ". 
I 4- They arc decomposed by (he action of (he a 
powerful acid supporters, and converted either inb I 
other combustible acids ; or each of their constiDMB | 
is saturated with oxygen, and converted into osidea 
acid products. 

5. The combustible acids may be very conveoienl 
subdivided into four orders ; which are diilioguilh^ 
from each other by the following properiies : 

The acids belonging to the first order Are crytuS 
zablc, and they may be rola[ilixed by heat without vk 
dergoing decomposition. 

Those belonging- to the second order are I 
crystallizable, but they cannot be Tolatilized trithoUtl 
composition. 

• The French chcmitti who formn] the new noinrncUturc ■wttt tf 
led here. They aiiAc umc ol the nunc* of ihc combuitiUc k4i||1 
in iV, u i[ ihcj wen uturaietl with oi]rg<ii ; aod olhcn in Mr, Ull 
tbejwcre capable □( comb ising with >n iddilioDil cIuk. Tbcfaci^ 
ilii( n«ie of ihcm arc, lUiclly speaking, lalunted with otTf^: fatd 
d ihtm ire capable of combiQing vrith mtrt. Bu ihcn thcjr a 
'fciae with more without bein^ (oialljr drtompoieil, aiul convened ^ 
water, urbonie icid, &c. I have iduplfd the rule rropotcd by Mr Q 
nerii, which ii catcuLtted [oituid ill ambigu'ljti the niniM «f all A 
cwiibuitiblc acidi are niiJe to fiul in ■•:, and ihit vriiheut rctetncl M 



'■ COMBUSTIBLE ACIDS. 

belonging to the third orderareootcryitalllzable. 
' the fourth urder axe placed three acids> which, 
: singulaiiiy of their properties ought to be se- 
From the rest. For want of a better name we 
inguish them by the term colorific. 
allowing Table contains the names and corn- 
arts of all the acids belonging to each of these 
s far as thej have been ascertained. 

IDCX I. Crystallizable. Volatilizable. 



[>nia. 


CoiulitueaiL 


Etic 

wic 

acic 

^nic 

Toxylic 

nphoric 

tlic? 


Carbon, hydrogen, oxygen. 


ER II. Crystallizable. Not volatilizable. 


Jlitic 
laric 
ric 
ic 
lactic 


Carbon, hydrogen, oxygen. 


= 


Carbon, hydrogen, azole, oxygen. 


■dc 




Order III. Not crystallizable. 


lie 
wric 


Carbon, hydrogen, oxygen. 




dtTt 



JD0M»U8TI«|«. dMSM* 




OxfiER IV. Cbloriic. 



^■Iirtwi 



R 



•met. 



MMI* 



Gallic 



Prussic 



S. dAI^lititeted 
hydrogen 



ix 



■ii^<< 



GmrboDy hydrogen, tajfa. 



Carbon, hydrogen, azote. 



Sulphur, hydrogen. 



We sbiU cc»naider the ^operttea ^f the acida U 

lo the three first orders in the following Sectiom 
fourth order, for reasons to be assigned hereafti 
occupy a separate Chapter. 



SECT. I. 



vinegar. 



OF ACETIC ACID. 

■ 

Xhis acid is employed in three difierent states 
have been distinguished from each other by ] 
names. When first prepared, it is called v 
Vfhtn purified by distillation, it assumea the i 
distilled Tinrgar, usually caHed tictttms acid byd 
%vhen concentrated as much as possible by pecol 
cesses, it is called radical vinegar^ and by chemi 
tic acid. It will be necessary to describe each i 
states separately. 

1. Vinegar was known many ages before i 
covcry pf any other actd, those only excepted 
exist ready formed in vegetables. It is mentioi 
Moses, and indeed seems to have been in comz 



ACETTC. rrfr 

MUig Ibe Israelites and other easlem nations at a very Chip. II. 
rly period. It is prepared from wine, from beer, ale, — 

«3 tttber similar liquids. These arc apt, as every one 
■Aws, la turn soar, unless they be kept very well cork- 
II Now sour wine or beer is precisely ifae same with 
■Mgar. 

• fioulutave deicribet the following method of inaking 
', which is said to be still practised in different 



Take two large oaken vats or hogsheads, and in each ^."J>^^ 
>^lbcse place a wooden grate or hurdle -at' the distance 
if a foot from the bottom. Set the vessel upright, and 
10 the grate place a moderately dose layer of green 
Vwigs of fresh cuttings of the vine. Then full up ibc 
'\-essel with the footstalks of grapes, commonly called 
Ibc raff, to the top of the vessel, which must be left 
^aile open. 

Having thus prepared the two vessels, pour into them 
the wine to be converted into vinegar, so as to fill one 
of them quite up, and the other but half full. Leave 
them thus for twenty-four hours, and then fill up the 
half-filled vessel with liquor from that which is quite 
full. Four-and- twenty hours afterwards repeal the 
AStoe opeiaiioa ; and thus go on, keeping the vessels al- 
ternately full and half full during every Iwenty-four 
faoDTs lilt the vinegar be made. On the secoad or third 
day there will arise, in the half.fiUcd vessel, a fermen- 
tative lUDlion, accompanied wilh a sensible heat, which 
will gradually increase from day to day. On the con. 
trary, the fermenting motion is almost imperceptible in 
ihe full vessel ; and as ihe two vessels are alternately 
full and half full, the feimentntion is by that means, in 



COMBUSTIBLE ACrOa. 

some ncBtutc, interrupted, and ii only reaewtd r 
' other da; in each vessel. 

When this motion appears to have entirely c 
«veniii (hehalf-fiUed vessel, ilisasign that the formal 
tation is finished ; and therefore the vinegar is ll 
be put into casks close stopped, and kept in ■ 
place. The process in su miner usually lasts fifteettdiyiA 
in winter it lasts longer *. 

All that is necessary to convert wine or beeraiftfl 
vincgitr is the contact of ihe external air, a 
of S0°, and the presence of some substance to • 
ferment. Rut the theory of this operation bdongitt I 
the Second Fan of this Work -, our business at p 
is, not to invesligalc the method of making vincf^r, btf 
to examine the properties of acetic acid. 

Vinegar is a liquid of a reddish or yellowish colw, 
a pleasant sour taste, and an agreeable odour. Ittipb 
cific gravity varies from rOl35 to I'OSal, and it dif- 
fers also in its other properiici according lo the liqoil 
from which it has been procured. It is very subject H 
dccotnpositionibutSchei-lediscoveredithai ifit bemadi 
to boil for a few moments, it may be kept aittrvmHi 
for a long time without alteration. Besides acetic scit 
snd water, vinegar contains several other ingrediei 
>uch as mucilage, tartar, a colouiing matter, and oftfll 
also two or more vegetable acids. When distilled ai 



* An Ktoiini ortbeDwde ofmikiiv vincfu JnPtasiee, ^moN 
(iKl|r die Mine with tlut given in the lac, wai paUitkol in the f 

■upliical TtauuciioBi fur if'jo, tdI. v. p. tcoi. 1'lic nicthoili >t pi 
ptaitiKd in France ate dcKribed iit the jd Volunic ol llic EIrmrmi i 
ni'r, puMiihcd by l)ie Dijqn Academy , p. 6. Mutjr «iU follow the pi 

.-e>) dciccibcd in ihc tcit s oilicni diffcrcai one. 



temperature not exceeding that of boiling water, (ill a- 
bout iwo-thirds, or five-stxihs at most, ol ii have pass- 
lover, all these mpurities arc left behind, and the pro- 
ict i* pure add, diluted with water. The residuum 
•till an acid liquid, and often lets fall crystals of 



2. The acid thus obtained is a liquid as traiispareni Ar^toua 
and colourless as water, of a strung acid ;aslt and an 
agreeable odour, somewhat dUrureDi from that of vn)<;« 

gar. In this state it is usually called acetous add or 
tiutiUed vinegar. 

It may be preserved without alteration in close ves- 
sels. When exposed to a moderate lical, iievapoiaics 
completely and without undergoing anv ch-iiigc in its 
properties. When exjiosed to the acticii of cold, part of 
it coDgeals. The frozen ponioii, which consists almost 
entirely of water, may be casilv separated} and by this 
method the acid may be obtained in a high degree of 
concentration. The more conctntraied the acid is, the 
greater is the cold necessary to produce congelation. 
IVfr Lowitz has ascertained thai the acid itself, how 
much soever it be concentrated, crystallizes or congeals 
ai the temperature of — 22". 

3. When asetate of copper, reduced to powder, is put ^^^''^ 
into a retorf'and distilled, there comes over a liquid at cecic iiciiL 
first nearly colourless and almost insipid, and afterwards 

a highly concentrated acid. The distillation is to be 
continued till the bottom of the retort is red hot. What 
remains in it then is only a powder of the colour of 
copper. The acid product, which should be received 
in a vessel by itself, is tinged green by a. link- copper 
which passes along with it -, but when disiilied nver 
again in a gentle heat, it is obtained perfectly colourless 



262 COMBUSTIBLE ACIDS. 

Bool H. and transparent. The acid thus obtained is esocedms. 

I ^ Ij pungent and concentrated. It was formerly distil. 

guished by the names oi radical vimegar and viatgat %j 

This process was known to the akhymtsts, and \ai 
often been repeated by chemical philosophers ; bnt tfat 
prodact was considered as merely hijghly odocentraled 
acetous acid, till Berthollet published his experimeiti 
on itin 1785 *• That skilful philosophy affirmtd^flMI 
it differs from acetous acid in taste artd smell, in its affioi. 
ties for other bodies, and in the compounds which it 
SoMowd forms with them. When it is Obtained from acetate of 
dUfefeBt copper by distillation, the powder which reBiaiiis in the 
retort con&ists chiefly of copper in the metalUo state. 
Hence he supposed, that the acetic acid gave out phlo* 
giston to the copper, and received from it ozygeo. 
When the existence of phlogiston was disproved, this 
theory was a little altered. It was concluded, that dv 
ring the distilktion, the acetic acid deprived the oxide 
of copper of its oxygen, and combined with it ; and thst 
radical vinegar therefore is acetous acid combined with 
a new dose of oxygen. For this reason it received the 
name of arctic acid. 

This tlieory was generally admitted by chemists, till 
Mr Adet published his experiments on acetic acid ia 
ll!)! f. He observed, that when acetate of copper if 
di stilled y the products arc not only acetic acid and wa« 
ttr, bur likewise carbonic acid and carbureted hydro- 
gen gas ; and that the residuum consists of copper and 
cbarcosl. He found that acetous acid did not absorb 



* M.r. Var, 178J. \ Arnt . dt Cl'uff, txvii. 299. 



Acnic. H 

BKjrgen vrfaen dislUled bff black oxide cf manganese. Clui-II 
knd that acciic and acetous acids have exactly ihe samt 
ciTcct upon metals. From these and some ot^ r similar 
Cxpcrimenis, lie concluded that acetic and acetous acids 
do not differ from each other except in concentraiiun. 

This conclusion was considered as hasty, as he did 
not attempt to account for the very striking difference 
iu the taste and smelt of these acids, as he had nci- 
4bez repealed nor refuted the experiments of Bertho.tr r, 
«n which [he opinion of the difference beiv.ren these 
ivio acids IV a » founded. Tlie conclusi&r. of Adei was 
Opposed in liss b^ Chaptal, who pubhbhed a set ot ex- 
periments on the same subject". This philosopher 
fcndeavoured to demonstrate, as BenhoUet had done be- 
■iorc hiro, that acetic and acetous acids, even when of 
tbe same strength, posscaa difiLreiil properties, andliiive 
different effects on other bodies. From the effect if 
Mllphuricacid iipou each, and fiom the quantity of ciiai- 
-coal which remains m the retort when i^qual quantities 
of each SBluiated with potash are distilled, he concluded 
ahat acetous acid contains a sn.ailer proponion ot car. 
boo than acetic acid. And this he considered as the 
caute of the difference in their proptrlics. 

Jo 16U0 a new set ot cxperiiuents on the same sub- 
ject nai published by Mr Dabii ofNantcsf. This 
chcoust endeavoured to ptove that acetic acid contains 
a greater proportion of uxygcu than acetous. When he 
distilled a mixture ol acetate of potash and sulphuric 
acid, the product was acetic acid ; but when he ^ubsti- 
tnied mtuiaiic acid tor sulphuric, he obtained acetous 



CDMSL'STISLK ACIDS- 

scid ; but when to this list mixture b litile bliclc oxidij 
of manganese wai added, he assures us tliat he obtained 
acetic acid. And iji none of these cases wa« llicic uij 
carbonic acid cmiltcd till towards ibe end of the diiiil. 
Ulton. 

The experimenis of Dairacq have at last fmallj Kb 
lied this dispute, bjr demonstrating ihat acetous and i- 
celic acids dilTcr merely in concentration. This ablt 
chemist repealed ihc experiments o( Adet, which be 
foimd perfcctly^ accurate, and performed several 
ones i all of which left no doubt that acetous and a 
acids contain precisely the same proportion of oxjgeib 
lie tieiLi tried the opinion of Chaptal respecting the pro- 
portion of carbon in each. When ecjual quantities of 
acetic and acetous acids are combined with potash w 
Koda, the dry salts distilled leave the same quantity o( 
charcoal, and yield the same quantity of other produclt. 
When reduced to the same specific gravity, the two 
ucids form precisely the same salts with all alkaline 
and carlhy basc^. Finally, acetous acid gradually be* 
comes acetic acid when distilled repeatedjy ofTdry 
riaie of lime j and in this case no |;aseous body what- 
ever is evolved. I'Voni these facts, it is impossible to 
enlcrtain a doubt that the two iubilaiices are essentially 
the same, and that these apparent dificrenccs are ow'mg 
lo the great ({uantiiy of water with which acetous adi^ 
is diluted, and the niucilagiuous matter which it stiU 
retains ". 

The same results were obtained also by Proutt, wfaa 
had ilrawn the same condosiont before he cunt ic> 



* D^riacij, .^t. A Cilm. xV, 164. 



ACETIC. 365 

quainted with Darracq's paper ". Henceforth the term Chip. 11. 
' ttctttms add must either be wholly dropt by chemists, 
or employed in a sense diS(:(ent from what was former- 
\j affixed 10 il. 

4. This acid is transparent and colourless like water. Piopenicr 
' It has a peculiar aromatic smell when in the stale of 
acetout acid ,- but concentrated acetic acid, when procu- 
red ID the utual way, has an empyreumatic odour mix- 
ed with ihe natural smell of vinegar, owing to a small 
portion of oil formed during the process f. 

Another method of procuring this acid in a concen- 
trated Stale, has been proposed by different chemists, 
aod brought to a slate of perfection by Lswilz of Pe- 
tenburgh. Distil a mixture of three parts of acetate 
of potash and four parts of sulphuric acid, till the ace* 
tic acid has come over into the receiver. To separate 
the sulphuric acid with which it is in some measure 
contaminated, rectify the liquid by dislilliog it off a 
portion of acetate of barytcs. The acid that comet 
over cryslalliMs in (he receiver. 

The specific gravity of dittilltd vinegar varies from 
I'OOT to I'OogS i but radical vinegar is much more 
concentrated, its specific gravity being as high as 
1-080 J. In that state it is extremely pungent and 
acrid i and when it is applied to the skin, it reddens and 
corrodes it in a very short lime. It is exceedingly vo- 
latile ; and when heated in the open air, takes fire so 
rcadDy, that one would be tempted lo Suspect the pre- 
sence of ether in it. It unites with water in any pro- 






f A»ii,diCiim.iaiu. lit 



26<l COMBUSTIBLE ACIDS. 

^^ "« portion ; and when concentrtted. the murtnre evolves a 

Divittoo IT. 

< y I good deal of heat. 

5. Courtenvaux had long ago obseryed, that the hit ' 
portions of acetic acid, which* come over during tfaedit- 
tillation^ were susceptible of crystallizing in m made, 
rate cold. Lowitr proposed a very iDgemoot meA&i 
to obtain this acid in the state of crjratals. He ndw 
distilled vinegar into a paste with welUmmt ehareoil, 
and exposes the mixture to a heat not above 212*. 
The watery part is driven off, and the acid remains. A 
stro ng er heat drives off the acid itself in a very coo- 
centrated state. By repeating this process it may be 
obtained in crystals. The process of that chemist, de- 
tailed above, is more recent, and in every respect pre- 
ferable. 
Actum of 6. Neither oxygen gas nor air have any very mark- 
^'y^ ed action on this acid : nor do the simple combustibles 

or incombustibles alter it at the common temperature 
of the atmosphere. 

7. It is capable of oxidizing iron, zinc,coppery nick- 
el, tin. It does not act upon gold, silver, platinum, 
mercury, bismuth, cobalt, antimony, arsenic. Its action 
on tellurium, tungsten, molybdenum, uranium, titani- 
um, and chromium, has not been tried. 

8. It combines with alkalies, earths, and metallic 
oxides, and forms compounds known by the name of 
acetates, 

9. It is decomposed by sulphuric and nitric acids. 
The action of the other acids on it has scarcely been 
examined. It dissolves boracic acid, and absorbs car- 
bonic acid. 

10. It has the property of combining with a great 



ACETIC. 



F 

^Hplher of vegetable bodies, sucli as oils, mucilage, and 

^^mcnaiics. 

11. Whan nitric acid is made to act on this acid, it 
converts it into water and carbonic acid. When acetic 
Bcid, combined with a fixed alkali or caiili, is exploded 
lo B strong heal, it is almost completely decomposed ^ 
^w»ter, carbonic acid, and carbureted hj-drogen gas, arc 
cnitted, and the base remains mixed with a quantity of 
charcoal. From these facts it follows, that it is compo- 
■ed of carbon, hydrogen, and oxygen, into which all 
tfaese products may be ultimately resolved. But the 
proportion of these ingredienis has not been ascertained 
with precision. 

By distilling lesograinsof acetate of potash, Dr Hig- 
gcns obtained the following products * : 

Potash 3862-994 groifiB 

Carbonic acid gas 1413-564 

Carbureted hydrogen gas 1047*6018 

Kesiduum, consisting of charcoal 15*0000 

Oil , IBO-OOOO 

Water 940*0000 

Deficiency! 120*9402 

This deGciency Dr Higgins found to be owing to a 
quaotiiy of water and oil which is carried off by the 
cltutic fluids, and afterwards deposited by them. He 
calculated it, in the present case, at 100 grains of watcc 




4F«r Bj-i g 



■itu of otf gcu pi9 bid alx} diuipjKiret! from fhc lir tf 



COMBUSTtBLI ACIDS. 

ind 3c;-g402 grtim of oil. Now, since KcUteof pMid 
is composed of acetic acid and potash, aod nitcc 'i» 
whole of the polafth remained unaltered, il foUon, 
that the acid W9i converted into carbonic acid gu, a>> 
burcted hydrogen gas, carbon, oil, and wstcr ; all tt 
which arc composed of oxjgen, hydrogen, and cttrboi. 

Now I473'56i grains of carbonic acid gsa ate oe«> 
posed of lOfiO'fiea grains of oxj-gco aDd415'599 
of car boo. 

104'I*ti01& grains of carbureted bydrogco gn, 
a comparison of the experiments of Dr Higgina and I* 
voisier, may be supposed to consist of about ^li^Mi^ 
grains of carbon and 333'COlo of hydrogen. 

200*9402 grains of oil contain 103'4S28 
carbon and 43'4514 grains of hydrogen, 

1040 grains of water contain SS4 grains oFo^ja 
and 156 grains of hrdrogcD. 

Therefore 3S17 006 grains of acetic acid an cos 
posed of 1944'et.6 — 29'1=: 1915'866 grain* ©for 
gen, 5''v'4594 grains of hydrogen, and IsaS'CBl 
grain* of carbon. Consequently ion parts of 
acid are composed of 

50'lfl oxygen 
13'B4 hydrogen 
»5*8T carbon 

100-00 
These numbers can only be considered as vefyii 
perfect approximations to Ihe truth j for the object 
Dr Higgins was not to sscertain the proportiona of t 
ingredirnis which compose acetic acid i and therefl 
his experiments were not conducted with that rigidl 
curacy which would have been necessary for ibK fi 



IBlfZOtC. 

Me. MrProurtendeavoured to prove that azote likc- 
'■!te is a cimpuneni |}Ut of acetic acid \ an opinion 
hich had been eatertained by Lavoisier. But when 
'rommsdori' repeated the experiments of Proust, which 
Hisisted in dtsiilling different acetates, he obtained 
o mccs either of ammonia or of prusuc acid, as had 

announced bj> the chemist of lUadnd. Hence he 
poncludes titat acetic acid contains no azote, and that 

si's esperiments must have been made upon im- 

acid •- 



OF BENZOIC ACID. 



DSMZOIH, or BCNjAMiK as it is sometimes called, is a Hi«otj. 
kind of resin brought from the East Indies ; obtained, 
•cconling lo Dr Dryander, from the slj-rax benzoe, a 
tree which grows in the island of Sumatra. This sub^* 
Stance consists partly of a peculiar acid, described as 
long ago as 1608 by Blaise de Vigenere, in his Trea- 
lise on fire and salt, under the name oijio-weri of hen- 
tMH, because it was obtriined by sublimation ; but it is 
BOW denominated heitaoic add, 

1. Tlie usual method o^ obtaining this acid is to pat Prceuv 
K qwaniity of benzoin, coarwly powdered, into an earth- *""'• 
to pot) to cover the mouth of the pot with a cone of 



• Am di LtiM. Itiii 190L 

T 



99f0 COMBUSTIBLE ACTOrS. 

Book If. thick paper, and then to dpplj a ^try moderade slni 
heat. The benzoic acid 15 sublimed, and attaches itsdf 
to the paper. This method was tedious a«i4 difficnh; 
it being hardi j possible to prerent the heat from icorek 
ivg the benzoin, and volatilizing some empyteiKw 
oil, which soils and injures the acid sublimed. Nes- 
man proposed moistening the benzoin wiih aleohdianl 
distilling it in a retort with a low heat. The sdl 
comes over immediatelj after the alcohot, pmtlj mcrjm 
stals and partlj of the consistence of butter*. G^ 
froy ascertained, in 1739, that this acid m^ be obtaiiu 
cd by digesting benzoin in hot water. A portion ii 
taken up, which is deposited in crystals as the water 
cools. Schcele published a different method in 1775; 
which being easier and more productive than any of the 
preceding, is usually preferred. This process is ufol* 
lowsf : Upon four parts of un slacked lime pour twdit 
parts of water, and after the ebullition rs over add OS 

■ 

parts more of water ; then put 12 parrs of finely povad* 
ed benzoin into a tinned )>an ^ pour upon it first abool 
six parts of the above milk of lime, mix theni well to- 
gether, and tl)»s successively add the restof tlie nixtwt 
of lime and water. If it be poured in all at once, tKe 
benzoin, instead of mixing with it, wrll coagulate, and 
run together info a mass, lliis mixture ought to bt 
boiled over a gentle fire for half an hoar wich eenstaM 
agitation ; then take it from the fire» let it stand quitl 
for an hour, in order that it may set-tle ; pour off the 
supernatant limpid liquor into a glass vessel. Upon the 
f emainder in tlie pan pour oa parts of pare water > 



» Newman's Cbemiurj, p. 294. f Schcclf, l W%^. 



]IENZ0I(!. Sii 

loil them together for half an hour, then take it froib Chaft-^^ 
the fire, and let it settle ; add the supernatent liquor to 
the former ; pour upon the residuum some more water, 
boil it as aforesaid, and repeat the same process once 
more. At last put all the residuums upon a Bltcrr, ana 
pour hot water several times upon it* During this 
|NX>cess, the calcareous earth conlbines with the acid of 
Benzoin, and svparates it from the resinous particles ot 
this substance. A small quantity of the resin is dis- 
solved by the lime-water, whence it accjuires a yellow 
colour* All these clear yellow leys and decoctions are 
to be mixed together, and boiled down to 24 parts^ which 
then to be strained into another glass vessel* 

After they are grown cold, muriatic acid is to be add- 

, with constant stirring, till there be no farther pre- 
cipitation, or till the mass taste a little sourish* The 
benzoic acid, Tvhich was before held in solution by the 
lime, precipitates in the form of a fine powder. 

Mr Hatchett has observed, that when benzoin is di- 
gested in sulphuric acid, a great quantity of beautifully 
crystallized bentoic acid is sublimed. 'I'his process ii 
the simplest of all, and yields the acid in a state of •pu-'- . 
rity ; it claims therefore the intention of manufactu- 
rers •* 

2. Benzoic acid, thus obtained, is a fine light whitish Propertlti* 
powder, which is not brittle, but has rather a kind of 
ductility. Its taste is acrid, hot, and somewhat bitter. 
lis odour is slight, but peculiar and aromatic f . Its 



• Hatchctt*s Ail(!itional Expcrimi nt« on Tannin. PBil. Trams, i8oj. 

f This odour is ow«ng to a sn'iall portion of aromatic oil w ich ad^ 
heres to the acit^ It han beeo obtained without any imell by Giae, 
Set Bbit. Mag, iiT. 331. 




^ 



COMSITSTIBLE ACIDS. 

Specific gravity is O'Cfli t- It hardly affects ibc iofoa 
sion of violets, but it reddens that of turnsol, cspcciatlj 
when hot ||. 

Heat volaliltzes this acid, aod makes it give ouia 
strong odour, which excites coughing. When ejtpo 
to the heat of the blowpipe in a silver spoon, it melu^ 
becomes as fluid as water, and evaporates willioul M 
king fire. It only burns when in contact with fluB^ 
and then it leaves no residuum behind. When ibrom 
upon burning coals, it rises in a while smoke. Wlm 
allowed to cool after being melted, it hardens, and wtu 
diated crust forms on its surface ^. When distlD^ it 
dose vessels, the greater part of it sublimes unaltered 
but some uf it is decomposed. This portion is C 
verted almost entirely into oil and carbureted bydrogti 
gas. 

3. This acid is not altered by exposure to the air. 
Cold water dissolves no sensible quantity of iti bntit' 
is soluble enough in hot water: 460 gr;iins of botliif 
water dissolves 20 grains of it ; IP of these are depo. 
sited, when the water cools in longr slender, flat, Ceft> 
ther-like crystals *. 

4> It is not flSi-'Cted by oxygen gas, nor by aayof tlit> 
simple combustiblcj or tncombusliblcs. It does not 
seem capable of oxiHizing any of the metals f. 

i. It combines with alkalies, earths, and metallic 0& 
ides, and forms salts known by the name of benzoatii. 

6. Concentrated sulphuric acid dissolves it without 



t HuKfihtz, A-n. i. Ctim. iXTiii'. 1 1. 
n Motvcaq, EiHyi. MtthtJ. Ctim. I. 44. 
* IbiJ- t Trommtdorf. 



BEBACZG. 203 

lieaty or anj other change, except becoming somewhat ^Chi p. u. 
brown : when water is poured into the solution, the 
benzoic acid separates, and coagulates on the surface 
nrithout an j alteration \ Nitric acid presents precisely 
the same phenomena, as does also the sulphurous a- 
dd. Neither the muriatic, the ozjmuriatic, nor the 
phosphoric acids dissolve it« Acetic acid, when bot^ 
lissolves it precisely as water does ; but it crystallizes 
■gain when the acid cools f. 

7* Alcohol dissolves it copiously, and lets it fall on 
the addition of water {• Boiling alcohol takes up its 
own weight §• 

This acid is sometimes used as a medicine, but much 
less frequently than formerly. 



SECT. III. 



OF SEBACIC ACID. 



(Chemists had long suspected that an acid could be 
obtained from tallow, on account of the acrid nature of 
the fumes which it emits at a high temperature ; but it 
was M« Grutzmacher who first treated of it particular* 
ly, in a dissertation De Ossium Medulla^ published in 
17481]. Mr Rhades mentioned it in 1753; Segner 
published a dissertation on it in 1754 ; and Crell exami- 



♦ Lichtenstcin. f Id. | Id. $ Wenzeri Verwandi^ 

:chafii p. 3c«. B I«co&hardi. 



£94 OOMBUSTJ^LjC ^PIDS. 

Book II. ncd Its properties vpry fully in two dissertations pubt 
C-^'T ^ lished in the Philosphical Transactions for JISO «i4 
l'S2. It ^as called at first acid of Jet, ajid afterwaidi 
sehacic acid. 

But at the period \ahcQ thes^ chemists m^f^ their 
ejcperimeittS| the ciiarfcrei istic properties of the difftreqt 
acids were not suQkicntlv l^nowu to enable themtodtt- 
tinguish acid*> from each othtr uith precision. Tbenvd 
examihcd the subject in ISOlj, tritd all the procesietoC 
Crcll itnd Guy ton Moivtau, and lound that the acidt 
procured by them were eith^ acetic or the acid cnploj. 
ed in the process. Re.\l stbacic acid had hitherto c* 
fcaptd the examination oi che^iis^s. Thenard found, 
however^ that a peculiar acid u a^ formed during thf dis- 
tillation ot'talow. 1*0 it he consi^'ned the appellation 
oi scbacic acid. TliC cxj^iimeiits* of this chemist were 
repeated in isp4 by Mr Rose, who obtained similar re. 
suits, and coniiinu-d all the obsirvations of the Freoch 
philoNopher *. The subject hsb lately been resumed 
by Mr Berzclius, who in an elaborate dibsertalionj, pub- 
li:>hed in lS()b> has shown that the scbacic acid of 
Thenard bears a close rebcmblance to benzoic acidf. 
Indeed he coi.siders it a^ nothing elbe than benzoic acid 
contiin>inatcd with some ui.known substance derived 
from the fat, which alters some of its properties, but 
from which it may be nearly frt^rd by proper pre- 
cautions, 
yxrpaya- 1. The method of procurinpr scbacic ac:d pointed cat 

by Thenaid is as follows : Distil hog's lard, wash the 
product with hot water, separate this water, and drop iniq 



• CcMcn*;* Jour. iii. iro. \ il,ij. id Series, ii. i;;. 



o 



k cnetateof lead. A flaky precipitate appears, whieh is ^Cha p. I 
to be washed and dried, mixed with sulphuric acid, and 
licated. A melted substance^ analogous to fat, swims 
on the surface, which is to be <:arefulJy separated. This 
sabstance is sebacic acid. It may h^ dissolved in hot 
vrater, and on cooling crystalline needles are deposited. 
Xihia acid may be obtained also by evaporating the wa- 
ter employed in washing the product of distilled hog's 
faurd* Or this water may be saturated with potash, and 
^rerwards precipitated with acetate of lead as above *« 

During the distillation there comes over abundance 
of gas, which appears to be a mixture of carbonic acid 
•and carbureted hjdrogem Into the receiver there drops 
4i yellow^coloured water, impregnated with acetic acid, 
imt containing no sebacic acid. it may, therefore, be 
put aside. But a much greater portion of oily matter 
passes over of the consistence of butter. The whole 
aebacic acid is contained in this matter, and may be se- 
parated by boiling it in water and evaporating the wa« 
aery solution. The sebacic acid falls down in the state 
of small crystals. From the experiments of Mr Rose, 
we learn that the quantity of sebacic acid formed by this 
process is extremely small 4 a pound of hog's lard 
yielding little more than 40 grains, and tallow or suet 
atill lessf. 

2. Sebacic acid is while 4 it has no smell; its taste Propmet^ 
is a pleasant sour, leaving in the mouth a very slight 
impression of bitterness. It reddens the infusion of 
tomsol. When heated it melts like tallow : on cooling 
tt concretes into a crystalline mass* By a sudden and 



* Aiw, lU Ch'm. um. 194. t C^l^n, til 171. 



f M COICfiOSTIBLB AfclOS. 

Book IL violeat beat it is decomposed. Berzeliiis bts sboin 

X>ivnioDlL . 

^at it maj be volatilized without decompositioD, hv 

that it requires a higher temperature for this porpoie 

than benioic acid. 

Cold water dissolves but little sebacic acid, but boil, 
iog water takes up one-fourth of its weight. It sept. 
rates as the water cools in small crystals. The crystds 
are needles ; but by proper precautions it may be pro- 
cured in long, large, and very brilliant plates. Aleo* 
hoi dissolves it copiously, and so do the fixed and vols* 
tile oib,*. In all these respects, as Berzelius has showsi 
it agrees with benzoic acid. 

It occasions a precipitate in the acetate and nitrate of 
lead, the nitrate of silver, the acetate and nitrate of mer* 
cury. It forms peculiar salts with the alkalies and 
earths. It does not render lime-water, barytef|0r 
strontian water, turbid. Sebate of potash has little XM^ 
does not attract moisture from the air ; and when tnl* 
phuric, nitric, or muriatic acid is poured upon it, leha- 
cic acid is deposited : when its solution is concentrated 
and mixed with any one of these acids it becomes so- 
lid. Berzelius has shown, that in these properties alio 
sebacic and benzoic acid agree with each other. He 
has compared the different salts which each of these 
acids forms with the respective bases, and shown that 
they also nearly agree in their properties. Benzoic acid 
is usually combined with some extractive matter, from 
which it is nearly as difficult to free it as it is to free 
sebacic acid from the substances with which it is united, 
in short, from the experiments of Berzelius, there can 



* ThcDard ojid Rote, IbiJ. 



(doubt that the two adds, if not absolutely thr Chip.ii 
» at least approach very nearly to each olher. 



OF SOCCINIC ACID. 



^UIBEK is a well-known browr, transparent, influn- Hiuorr. 
Oiabli' body, pretty hard, and susceptible of polish, found 
■t vomc depth in ihe earth, and on the sea-coast of le- 
venl countries, h was in hi;;h e^iimaiion among the 
asciepts both as an orn^mcit and a medicine. — When 
this substance is distilled, a volarile salt is obtained, 
which is meniioned by Agricola under the name oi salt 
of amber i bui its nilure was long unknown. Boyle 
was the first who discovered that it wag an acid *. From 
MKvnwt, the Laim nam- of amber, this acid has recci- 
ved il>p appellation of luccinic acid. 

Mr pott seems to h;ive been the first chemist who 
nudeasetof experimenis lo ascertain its properties, and 
wfao demonstrated thai it difTtrs from every oiherf. 

I. It is obtained by the following process: Fill are- Prrp*™- 
tsrt half-way with powdered amber, and cover the pow- 
der with a quantity ot dry sand i lute on a receiver, 
and distil in a sand-bath without employing too much 
he«t. There passes over first an insipid phlegm ; then 



■ Bojic abridged by Shit*, lii. Jf-g. 
f tttm. triim, ija if da abKrsCC uf liis paper il 
«JMtvnun'( Citmiiiry, f, sj;. 



Lcwla't cditiun 



COMBViTZBU ACIDS. 

Bobk II. a weak acid, wliichy s^ccordtng to Scbeelc» if thcMctic^t 
'i then the iuccinic acid attaches itaelf to the veckftf the 

retort ; and if the distillation be continued, there coma 
ovtT at last a thick brown oil, which has an acid ta«i!e. 

The succinic acid is at first mixed with a quaotitj of 
oil. It maj be made tolerably pure by dissolvinj^ itii 
hot uatcTy and putting upon the filter a little coiioo, 
previously moiatciied with oil of amber : this substaLce 
retains mr st of the oil, and allows the soiUtion to pan 
clear. The acid is then to be crystallized by a geqtle 
evaporation ; and this process is to be repeated till tbe 
acid be sufficiently pure. Guy ton Morveaa has showi 
that it may be made quite pure by distilling off it a soJ- 
ficient quantity of nitric acid, taking care not toemploj, 
a heat strong enough to sublime the succinic acidf. 
Property ^' '^'^ crystals of succiiiic acid are transparent, whilfip 
shining, and of a foKuted, triangular, prismatic form: 
they have an acid taste, but are not corrosive: tlMj 
redden tincture of lurnsol, but have little effect oo thit 
of violets. 

lliey sublime when ex{X)sed to a considerable heat, 
but not at the heut of a wiiter-bath. Jn a sand-bath tbcy 
melt, and then sublime and condense in the upper part 
of the vessel ; but t!.e coal which remains shows that 
they arc par:ly decomposed J. 

3. One part of this acid dissolves in 06 parts of wa. 
ter at the temperature of 50**, according to Spielman {; 
in 24 parts at the temperature of 52** ; and in 2 parii 
of water at the temi^erature of 2 J 2°, according to Stock- 



* Bef|;nun*t Motet on SchciTcr. f Am. dt Chim, zxU. 165. 



SUCCINIC. 909 

de Neufom * ; but the greatest part crystallizes as Qhay.IL 
le water cuols. According to Roux, however, it still 
ttains more of the acid than cold water is capable of 
issolvingf. 

Xwo hundred and forty grains of boiling alcohol dis- 
>lve 177 of this add ; but crystals again shoot as the 
elation cools {• 

4* Sulphuric acid dissolves it with the assistance of 
i«at ; but does not appear to decompose it. The same 
canark applies to nitric acid. Muriatic acid has but 
iule action on it while cold ; but when heat is applied, 
he whole coagulates into the consistence of a jelly §. 

5. The compounds which this acid forms with alka* 
icsy acids, and metallic oxides, have received the name 
vt succuuitei. 

6* When combined with soda, it crystallizes in four 
Mi4 tix sided prisms. When this salt isdistilledin a re- 
lort, the succinic acid is completely decomposed. There 
passes over into the receiver an acid liquor, which is the 
icetic much diluted, and a quantity of brown oil. At 
ihe same time carbonic acid gas and carbureted hydro- 
gen gas are disei gaged, and their remain in the retort 
soda and charcoal ||. Hence it follows, that this acid, 
like the others of the same class, is decomposed by 
beat, and that it is composed of oxygen, hydrogen, and 
Wbqp. 



* Dt Svcduo. t MonreaUi Emey€, Mtth^d^ Chim, i, 7s, 

t Wcnzert errvamitschaft^ p. 3OJ. { Pott. 

I Morteau. Am, dt Ciim, ixix. 165. 



300 COMBUSTIBLE ACIDS. 

Book rr. 

DiviuoD If. 



SECT. V. 



OF MOROXTLIC ACIP. 



Hittoiy. About the year 1802, Dr Thompsoa obsenred t nUie 
exudation on the bark of the morus alhat or white nud. 
berry tree, growing in the botanical garden of Pakroo 
in Sicily. It coated the bark, of the tree in small graim 
of a yellowish and blackish brown colour. A qoaalii 
ty of this matter was collected and sent to Mr Klapmhi 
who published an analysis of it in 1803 *• 

It has a taste resembling that of succinic acid ; and 
when placed upon burning coals, it emits a yapour whkh 
irritates the organs of smell. In water it dissolves da- 
ringly, forming a reddish-brown liquid, which yieUi 
by evaporation small needlefDrm crystals, of die coloiir 
of pale wood, not deliquescing in the air. Bj dissoU 
ving these crystals in water, and treating them with varia 
ous reagents, Klaproth ascertained them to be fenned 
of lime united to a peculiar acid, which be called im- 
roxylicp because the salt containing it was a prodoctioa 
of the wood of the mulberry tree* 

The salt dissolves but sparingly in water j hot water 
laking up only 0*035, and cold 0*015 of it. From the 
solution the alkaline carbonates precipitate lime ; bat 
barj tcs causes no precipitate ; a proof of the absence of 



• Sthercr's Journal Jer Ciefr.h^ No. $$, p. i. But I use the tnuubcioo 
cf the paper pablishcd in Niiiholson'i Journal^ fij. 119, 



H0IIOZTI.IC. SC 

Ifthoric acid. It precipitates powerfully the solutions , Cbi p- 1 
silver, mercory, copper, iron, cobalt, and uranium, ia 
.trie acid ; and of lead and iron in acetic acid. Ba- 
rtcs water, acetate of barytes, muriate of tin, muriate 
gold, and niirate of nickel, produce scarcely any ef. 

Dt. 

To obl^n the acid, the solution of the salt was treat- 
1 with acetate of lead. ForCy-five grains of the pre- 
ipttaie thus obtained were mixed with 20 grains of sul- 
c acid diluted with GO grains of water. The sul- 
of lead formed remained in the state of a white 
lowder, while the moroxylic acid was dissolved and ob- 
tined by evaporation in the slate of fine needles of the 
wlour of pale wood. 
The acid thus obtained has the taste of snccinic acid : "'*I*"^ 
is not altered by exposure to the air: it dissolves rea- 
lily in water and in alcohol : it docs not precipitate the 
letallic solutions like its sale. 
When heated in a retort, a little acid liquor first 
over, which has the taste of the concrete acid: 
the acid rises unaltered, and adheres to the top and 
Beck of the retort in colourless and transparent prisma- 
ic crystals. A coaly residuum remains in the vessel. 
Bence it appears, that a gentle sublimation is the best 
node of obtaining this acid in a state of purity. 

When the calcareous salt of moroiylate of lime is 
Sistilled, a quantity of inflammable air mixed with car- 
bnnic acid is obtained, and an acid liquor comes over, 
on which swims a brown oil. There remains in the 
letort a spongy mass of a pale brown colour, consisting 
of carbonate of lime mixed with some charry matter. 
Fiom these phenomena it appears, that this acid, like 
the rest, is composed of oxygen, hydrogen, and carbon, 



S02 COMBUSTIBLE Atmt^ 

B«* It, though the proportion of the conttttuents is unltioti I'' 
Tlie compounds which it forms with alkalies hsveiet §^ 
ceived the name of moroxj/atei. 

Such are the properties of this substance ascertsi^ 1^ 
by Klaproth. The small quantity of the salt whichh 1^' 
possessed prevented a more complete ezamxuatioii. 1^ 



tlOO. 



SECT. VI. 



or camfhOric ACity^ 



Hkory. Camphor is a well-known white crystalline submic^ 
of a strong; taste and smel]| obtained from a tpeeictof 
laurel in the East Indies. It is so volatile that it on- 
not be melted in open vessels, and so inflammable tlal 
it bums even on the surface of water. 

When camphor is set on fire in contact with ozjga 
gas, it bums with a very brilliant flame ; much calorie 
is disengaged, water is formed, the inner surface of the 
vessel is covered with a black matter, which is na* 
doubtedly charcoal, and a quantity of carbonic acid gis 
is also produced *• Hence it follows, that it it coia* 
posed of hydrot^en and carbon, at least principally. 

Mr Kosegarten, by distilling nitric acid otf cantpkor 
eight times successively, obtained an acid in crjstalst^ 
to which the name of camphoric acid has been ^iven. 

P^eparv !• ^^^ experiments h.tve been repeated by MrBoDil*^ 



* Bouillon Ls Gran;^, Ann. de Cbim, xxliu rjj. 
t SofCgartcn ift Camfb^ra^ &C. I •]%$• 



eAMPtlORIC. 909 

I La Grange. The process for obtaining camphoric Cfcip. O. 
i^ as described bj this chemist, is as follows : l^iit 

a retort one part of camphor and eight parts of ni« 
; acid» of the specific gravity I '3 3. Distil with a 
d heat. A great deal of nitrous gas and carbonic 

1 gas is emitted, and a little camphor sublimes. This 
cess must be repeated three times on the same cam- 
>r ; so that 24 pnrts in all of nitric acid are neces« 
y. After the third distillation, when the retort is 
>wed to cool, a number of crystals make their ap- 
.ranee In it. These are camphoric acid. They a* 
unt to somewhat less than the half of the camphor 
ployed. 

2. Camphoric acid thus obtained is in snow-wbife PropertSeib 
stals, of the form of parallelopipedons *. Tliese 

stals effloresce in the air+. 

Camphoric acid has a slightly acid bitter taste, and a 

ell like that of saffron. 

It reddens vegetable colours, 

3. Tt is soluble in 200 parts of cold water, according 
fosegarten ; in 90 parts of water af the temperafure 
50^, according to Bouillnn La Grange. Boiling wa« 
dissolves T^th of its weight J. 

According to Ko^eesrten, it is insoluble in alcohol ; 
ordlng to Bouillon La Grange, alcohol dissolves it; 
t when the solution is left in contact with the air of 
atmosphere, the acid crystallfres. It is not preci- 
ated from its solution in alcohol by the addition of 
tcr f. 



* KoiegartfD Jc Camphtra, &c. 1 785. f La Grange, 

t Koscjrirttiu { Bouillon La Gnmgr, Anfi. /# Ckkt* ]iivii« 40. 



304 COMBUSTIBLE ACIDS. 

Book IT. 4, When this acid is placed on ignited coals, it eniti 

-_ ^ ' a dense aromatic fume, and is entirely dissipated. Bj 

AcUonof ^ gentler heat it melts, and is sublimed. If it be ptt 

into a heated porcelain tube, and oxygen gas be pasKd 

through it, the acid does not undergo any change, hit 

is sublimed. 

By mere distillation it first melts, and then sublimes; 
by which process its properties are in some respect 
changed. It no longer reddens the tincture of turasol, 
but acquires a strong aromatic smell ; its ttfSte becomei 
less penetrating, and it is no longer soluble cither in 
water or the sulphuric and muriatic acids. Heated 
nitric acid turns it yellow and dissolves it. Alcolul 
likewise dissolves it : and if this solution be left in 
contact with the air of the atmosphere, it crystallizes. 

5. Camphoric acid does not produce any change on 
sulphur ; alcohol and the mineral acids totally dissolve 
it ; and so likewise do the volatile and the fat oils. 

Camphoric acid does not precipitate lime from h'me- 
water. It produces no change on the solution of indigo 
in sulphuric acid. 

G. It forms combinations with the alkalies, earths^ 
and metallic oxides, which are called campborates. 



SECT. VII. 



OF OXAI.IC ACID. 



HiVory. 



VV HEN nitric acid is poured upon sugar, and a mode- 
rate heat applied, tiie sugar soon melts, an effervescence 



T- 



oxAue. 



1 



a great quantity oi nicfouigu and cubonic ^id C>up.ll. 

1 is emincd j and when the effcrvescenn ceau*, and 

S liquid in the leloii is allowed to cool, a nunbei of 

all tfansparcnl ctysuUs appear in it. Thew ciyiXais 

Dstiiutc a peculiar acid, which has recciv«d the name 

»xaiic aci4, because it exists ready foinKd, as Scbeelc 

s proved, ia llic oxaiii acttotetla, or wood-sorrel. At 

|tai, however, i[ was called the acid of sagar, or the 

ueeharint atid. 

As the earliest and hest account of the oxalic acid 

U published by Bergman, he was for a long time 

eckoncd the discoverer of it ; hut Mr Ebrhart, one of 

fcbeelc's intimate friends, informs us, that the world is 

idebted for its knowledge of this acid (o that illuBtri- 

U obenttsi ', and Hermbstadt and Westrumb assign the 

lucovery to tlie same author f. The assertions of these 

jcatlemen, who had the best opportunity of obtaining 

(Cctiraie information, are certainty sufficient to establish 

|ie fact, that Scbeele was the real discoverer of oxalic 

1. 

. Bergman gives us the following process for ob- Pnpiri- 
siniog this acid : " Put one qunce of while sugar pow- 
jkred into a tubulated retort, with three ounces of 
ftroag nitric acid, the tpeci6c gravity of which is to 
^at of water as l*5fi7. When the solution is over, du- 
Inng which many fumes of the nitrous add escape, let 
HI receiver be fitted, and the liquor made to boil, by 
I which abundance of nitrous gas is expelled. When the 
liquor in the retort acquires a reddish-brown colour, 
~«dd three ounces more of nitric add, and c 



t'/t AftthHtr'm, \1%i% put i. p. lA- 



I 



COMBUSTIBLE ACIDS. 



boiling tin the fumea c«ue, uid the coloor of the Iiqa« 
vantthes. Thm let the contents of the retort be emp- 
tied into % wide vessel ; and, upon cooling, k crymlli- 
zatioo will take place of vlendcr qatdrUaicral prion, 
which ire often afTixcd to each other at an angle of 45*. 
These cr^ttals, collected and dried on blotting 
will be found to weigh i^^di. 19 gr. Bj boiling tlv 
remaining lixivium with two ounces of nitric acid ii 
the retort till the red fumes almost disappear, tnd 
repeating the crystallization as before, ^ dr. ISgr. 
solid acid will be obtained. If the process be 
once more upon the residuum, which has now a ghlil 
nous conustence, with ihe successive addiiiooa of 
quantities of nitric acid, amounting in all lo two 
a saline brown delJijuescent mats will be 
weighing half a dram, of which about a hsdf will 
lost by a farther parificatton. The crystals obtainci 
thus at diSierent times may be purified by solution nl 
crystallization, and by digcsiing the last liziviiin 
some nitric acid, and evaporation with the heat of die 

By the same process Ber^an obtained it from gna 
arable, alcohol, and honey : Scheele, Hermbstadt,Wes> 
tnimb, Holfman, $cc. from a great variety of Otber re* 
getable p -eductions ; and Berlhollet &oni agreat BUI- 
ber of aniii.at substances. 

It is of great consequence not to use too macb nilttt 
acid, otherwise the quantity of oxalic acid will be dtnu* 
nished i and if a very great quantity of nitric acid ba 
used, no oxalic acid will be obtained at all *. Ob Al 




SOT 



ittnrj, Hermbsbdt affirms, that if too small a quantity Ch»r. II. 
nitric acid be used, the acid obtained will not be the 

Xklic, but the tartaric. But I have not found this can- 
d upon trjing the experiment. A 100 grains of 

Dgar, when properly treated, yield 58 grains of crys- 

■Uized oxalic acid. 
2. Oxalic acid, thus prepared, is in the form of four- Propertiw. 
led prisms, whose sides are alternately larger, and 
cy are terminated at the extremities by two-sided sum- 
lits. They are transparent, and of a fine white colour, 
ith considerable lustre : they have a very acid taste, 
id redden vegetable blues. These crystals contain a 
ortioa of water, as happens to most crystallized bo- 
dies. When cautiously heated on a sand-bath they 
AdJ to powder, and lose about a third of their weight ; 

tet a part of this loss is to be ascribed to acid volaiili' 

Wd. From an accurate set of experiments made on 

purpose to investigate this point, I conclude them to be 

composed of '77 real acid 



So that the water of crystallization amounts very near- 
ly to Jtb of tbe weight '. 

3. When this crystalhzed acid is exposed to heat in J^"^ •' 
•n open vessel, there arises a smoke from it, wliich af- 
fects disagreeably [he nose and lungs. Tbe residuum 
is a powder of a much whiter colour than the acid had 
been. By this process it loses-Jdof its weight, but soon 
ncoven it again on exposure to the air. When dis- 



The reader uKferredrr i ict of eipcrintcnti bj me eo anlic icid, 
Ihc FUl. Trim, for iioj 

D 2 



OOMIUSTOILB ACIDS. 

tilled, it firit 1ok> itt water of crysUOUutioo, thru li 
( fie> and becoinci brown ; a little ptilegn paueicn 
a white uliuc cnist tubltmct, some of which (u: 
into ttic receiver ; faut tlie gieatcsi put of the acidi| 
deitrojed, leaving in the retort a mass tW*}* ^ 4| 
whole, which has an em pjrreu malic amell, falackai 
aulphoric add, rendcn nitric acid yellow, aod djssolfd 
in muriatic acid without alteration. That part of i|| 
acid which sul>liin«s ii unaltered. When tlu« acidii 
distilled a second time, it gives out a white lou 
which, coitdeniing in the receiver, produces a colooo 
leu uncrystallizabic acid, and a daik coloured i 
remain* behind *. During all iiii» distillation a na 
quantity of elastic vapour makes its escape. From X 
grains of oxalic acid, Bergman obtained 1 09 cubic tnck 
of gas, half of which was carbonic acid, and half orb 
rcted hydrogen. Fuotana from an ounce of it obtajad 
430 cubic iDchcs of ga», one-third of whidt was cvW 
nic acid, Ihe rest carbureted hydrogen. 

4. The crystals of oxalic acid arc soluble in tbctr oi 
weight of boiling water : water at the temperature of 
ilS"I° dissolves half its weight of them. The spccifit 
gravity of the solution ia 1'05S3 f. Ooe hundred p 
of boiling alcohol dissolve 50 parU of these crystaisi 
but at a mean temperature only 40 parts 1. Li^uiJ 
oxalic acid has a very acrid taste when it is conceotiv 
ted, but a very agreeable acid taaie when snttcientlydk 
luted with water ^. 

It charges all vegetable bines except indigo to a i«& 
One grain of cryataltixed acid, ditsolved in ItzO g 



water, rcddcBi the blue paper with which sugar Chtp-t^^ 
res are wrapt : one grain of it, dissolved in 3600 
iaa of water, reddens paper luined with lumsol *. 
ling to Mocveau, one part of the crysullizcd acid 

SuSident lo coamuintcatc a sensible acidity to 2033 

ins of waier f. 

Its fixity is such, that none of it is sublimed when 

uer containing it in solution is raised to the boiling 

nfMralure. 
5. Oxalic acid is not affected by exposure to the air, Pj^^^** 

r to the sctioD of oxygen gas. The effect of the 

nple corobascibles on it has not been tried; bat in 

1 pcobabilily is inconsiderable. 
It is capable of oxidizing lead, copper, iron, tin, bis* 

totb, nickel, cobalt, zinc, mangaiiese. 
It docs not act upon gold, stiver, platinum, mercury. 

0. Oxalic acid combines with alkalies, earths, and 
letalhc oxides, and forms salts known by the name of 

tttattt, 

1. Muriatic and acetic acids dissolve oxalic acid, but 
iriihoot altering it ]. Sulphuric acid partly decompo- 

it by the assistance of heat, and a quantity of char> 
goal is formed. Niliic acid decomposes it at a boiling 
beat, and converts it into water and carbonic acid $. 
From this result, and from the products obtained by 
distilling pure oxalic acid, it follows, that this acid is 

posed of oxygen, hydrogen, and carbon. The best 
method of ascertainitig the proportion of these consli. 
inenis, is to distil at a red heal determinate quantities 



' Btrgmui.L ;5;. \ Kriiyt- Alrlltif. »i 

I Oit^mtl: 5 Foottrej, TU, r. 



COHBOSTIBLZ AClDft. 

of dry oxalates. So far as mj ex|ieriments htvc pm, 
the oxalic acid is decomposed precisely in the 
way, and the same new products formed wtiatcrcr oi» 
late we u&e ; but the oxalate of lime is moKl coOTcnieo^ 
because we can ascertain its composition with the gmb 
est accuracy. When oxalate of lime is distilled iw 
small retort by means of a heat gradually raised lo iti. 
oess, the oxalic acid in completely decomposed and 
verted into five new substances ; namely, voter, corime 
arid, carbonic oxide, earharrtcd hydrogm, and cbarnd. 
The water is small in quaiitity, ihc carbonic add lar|^ 
and partly in the state of gas, partly combined with 
base of the oxalate. The carbonic oxide and ciil 
teted hydrogen are in lite slate of gases, and in tlie pio> 
portion of about 2\ of ihe former to 1 of the 
The charcoal is small in quajilily, and mixed with tlit 
residue in the retort, lo which it gives a grey coloort 
By carefully ascertaining the proponion of each 
these products, and c&iimaftog ihcir composition ate 
cording to the most exact analysis hitherto insde 
each, 1 found that the composition of oxaXw scid n^ 
be suted as follows, oxygen 64 

carbon 32 

hydrogen 4 



This result differs very considerably from that ai 
ccd by Fouicroj and Vauquelin as obtained by ittcii 
experiments. Oxalic acid, according to them, is com- 
posed of oxygen "ll, carbon 13, hydrogen 10*. Bull 



w 



SECT. VIII. 



OF MELLITIC ACID. 



1 



■m petsuaded that my nutubers are much nearer the 
umth tbiui these. The proportioa gf carbon contkined 
Lia tbc carbonic acid, evolved by the distillation of oxa- 
'iste of lime, is a good deal greater than the whole of 
tfae curboa which they assign to tbc compoutioa of oxa- 
lic add. 

Tills add is too expensive to be employed for the 
iparposcs of domestic economy ; but it is extremely use* 
fal in chemistry to delect the presence of lime held in 
solution. For this purpose, either a lillle of the pure 
acid, or of the solution of oxalate of ammonia, is dropt 
into the liquid supposed to contain lime. If any be 
present, a while powder immediately precipitates *• 
The reajon of this is, that oxalate of lime is altogether 
insoluble, and oxalic acid in conseciueacc is capable of 
y^^^limc firoro every other acid. 

Tx BEKE is a mineral of a hoQey-y«Uow colour which HiKorr, 
is found in small solitary crystals among the layers of 
Woodcoal at Anen in Thuringta. At first sight it has 
some resemblance to amber i but Werner recognised it 



' Pioviiled the liquid doei do( contain la cucat of mj of ilu 
pi^wciful icidi. In tbii raic ihe Cicea tUBK be Mlnmcd wilh ai 
nil bcjarc adding tli: oxilic acid. 



^^^E COMBUSTIBLB ACIDI. T 

|HHEMn. u 1 peealiar substance aboat the jcu 1700, Btid pn I 

■ it the name of htnigttti* (honey.ttone), wbicli Eortigi I 

inincrKtogim convcrttd laXo mtlktt. This mioeral ii I 

■ very rare. Hitherto indeed it hai been foand ooljji 

Thuringia and in Switxcrlatid*. 

McUitc has usually a honey-ycIlow colour, but tone- 
times a itlraw-yellow. It is always cry »alli red in oct^ 
hedrons, but they ate rartly entire \ somctiines iodMd 
almoit ihe whole of one of the pyramids is winiing. 
ThtM surface is generally smooth and brilliant, andis* 
teriarly ihcy have a glassy lustre. They arc semicraaii 
parent, brittle, soft, and easily reduced to powdo.. 
When pounded, they aanime a yclIowiali<giey colourf 
Their specific j^avity is about 1*550 f- 

Mineralogists soon discovered that mcllilo 19 pirtlj 

combustible; but lliey did oot agree about itsconp*. 

nent parts. Lampadius and Abich undertook ils cb^ 

miciil analysis about the same lime. AccordiD| t9 ibl 

first of these gentlemen, it is composed of 

8fi-4 charcoal 

3'3 biiuinea 

2'0 silica 

3-0 water 

According to Abicli, it contains the following ia{rt- 
dients 



• Brocbicl'i Mitral^, «. JS- 
t KUpnth'* M>r<i<,ui llj. 



IIELLITIC. 919 

40 carbonic acid Cfca^ W.^ 

28 water 

16 carbonate of alumina 

5t benzoic add 

5 benxoate of alnmina 

3 oxideof iron 

24 n^sin 

loot 

rbe retnlts of tbese analjaes diScred so moch from 
each other, that little confidence could be placed in 
either. Besides, it was evident from the way in which 
their experiments were conducted, that the original 
component parts of mellite had been altered by fire. 
Klaproth analysed it in llM, and ascertuned it to be a 
compound of alumina and a peculiar acid, to which he 
gUTC the name of melliiic %• And this analysis was soon 
ifter confirmed by Mr Vauquelin ||. 

1. Hitherto mellitic acid has been found only in the P'qpva- 

tioiu 

mellite. It may be procured from that mineral by the 
following process : Reduce the mellite to powder, and 
boil it in about 72 tinges its weight of water. The acid 
combines with the water, and the alumina separates in 
flakes. By filtering the solution, and evaporating suf- 
ficiently, the mellitic acid is obtained in the state of 
crystals. 

2. These crystals are either very fine needles, some- Propcrtici. 
times collected into globules, or small short prisms. 



f Crell*t AnMUt 1797, ii. p* 16. \ Biitrage, iii. 1 14. 

\ Amt* it dim* xizvf. aoj« 



CUMSUSTtSLE ACIDS. 

They have 1 browniih colour, utd i taste at first mttU 
iib-sour, and afterwards btiterith. 

3. Thit acid ii not verj soluble in water; bat t] 
Precise degree of solubility hat not beco asccnaiocd. 

4. When exposed to heat, it is rcadilj dccompoK^ 
cjibaling an abundant smoke, which however is dnii> 
tute of smell. A small quant! i; of insipid ashes i^ 
main beliind, which do not alter the colobr oflitnu^ 
paper. 

5. All stlempts to convert it into oxalic acid bjr t 
action of nitric acid have failed. The nitric acid nta 
ij caused it lo assume a straw-jellow colour. 

(S. The elTcct of the simple bodies on thia acid h» 
not been tried. 

7. It combines with alkalies, earths, and metallic ox* 
ides, and forms with them salts which ate distinguiik 
ed b^ the name of mtUatts. The properties of lliea 
compounds will be coosidcred afterwards. 

e. From the analysis of Mr Kiaproth, we lean thil 
the melliie is compoMd of 

40 mellitic acid 
16 alumina 
3S water 



Now when mellite is distilled in a retort, the scid is 
completely decomposed, and its elements combine to- 
gether in a different way. By this method Mr Kli- 
proiti obtained from 100 grains of mellite 
^4 cubic inches of carbonic acid gas 

IS hydrogen gai 

39 grains of acidulous and aromatic watci 
] aromitic oil 



n 



9 ••*..... cbarcoal 

16 alutniita 

From this analysis Jl is obvious, that inellitiG acid is 
iposed of carbon, hydrogeo, and oxygen, like moit 
of the cotobustible acids. Ii does noi, however, fur- 
msh us with sufficient data for ascertaining the propor- 
tion of these constituent pHiis. 

Mellitic acid hears a great reseroblance to the oxalicj 
bul it differs from it in many particulars, e^pedxily la 
the nature of the compounds which it forms with di£b> 
rent bases. 



or TAKTAXIC ACID. 



Xa«ta», or cliEAM OF TARTAR, » it 18 commonly jjj^ 
called when pure, has occupied the atleniion of chemists 
for several centuries. Duhamel and Grosse, and after 
them Margraff and Rouelle the Younger, pioved that 
it was composed of an acid uniiedio potash; butScheelc 
was the 6rst who obtained this acid in a separate state. 
He communicated his process for obtaining it to Ret- 
zius, who published it in the Sicckholm Transactions 
for 1770. It consisted in boiling tartar with chalk, and 
in decomposing the tartrate of lime thus formi'd by 
means of sulphuric acid. 

1. Theprocessemployedat present foroblMning tar- prtpm- 
taric acid, which is the same with that of Scheele, is *"^' 
;lie following : Dissolve tartar in boiling water, and add 



COMaVSTIBLE ACIDS. 

to ihc lolution powdered cbslk tUl all cfTcrvuccncc 
' ceawt, Bud the liquid does not redden Tc^etable bluti. 
Let Ibe liquid cool, snd then psn it lliroiigh > filun 
A quamitj of tarlrste of lime (which is nn inwlnUt 
white powder) remains upon the Rltrr. Put (hit ttf> 
traie, previously well wnihed, inio a gl&u cucutbiie, 
atid pour on il a. qaanthy of sulphtiric acid eqml la 
ihb weight of the chalk employed, which tnuM be 
led with water. Allow it to digest tm 12 hoor», 
ring it occaiiooally. The iiilph uric acid displaces Iht 
laiiaric : sulphaie of lime remains at the botloin, wbih 
ihe tartaric acid is dissolved in the liquid part. Decani 
off this last, and try whether it cootains any sulphuria 
acid. Ttiis is done by dropping in a little acetate of 
lead i a precipitate appears, wbicb a insoluble in acetie 
acid if sulphuric acid be present, but soluble if it be ab> 
sent. If sulphuric acid be present, the liquid must b« 
digested again on some more tartrate of lime ; if not, it 
is to be slowly evaporated, and about one third pan of 
the weight of the tartar employ od isobiaiocd ofcryttal- 
Ii»d tartaric acid. 

Lime may be substituted for chalk in this procesk 
lutbnt CISC the decomposition of the tartar is ceispleie 
wheieas by Sclteclc's method, ihe erxcesa of acid only 
combines with the chalk j but when lime is used, tht 
whole inrWatc of lime by no means separates. A coiu 
uderable portion is retained in solution by the potash 
of ihc tartar now disengaged. If the liquid be evapo. 
laied, this portion appears under tbe form of a transps. 
rent jelly. By exposure to the air the potash atlracti 
carbonic acid, which unites to the Kme, while tbe tar. 
taric acid combines again witJi the potash. To obuin 
tbe potash in a slate of tolerable purity, the best me- 



nod) aoCordiDg to Vauquelin, to whom we are indebt- . ^'"^ "- 
U for tbcK observation!, is to evaporate to dryness, and 
bcM the residue to redness. By iixivialing the mass, 
ifte potash wUl be obtained in a state of considerable 
Burity *. 

L2. Th« form of tbe crystals of tartaric acid is so ir- rropmis. 
guUr, that every chemist who has treated of this sub- 
lect has given adiSercni description of them. Accord- 
ing to Bergman, they generally consist of divaricating 
pUDcJIse f ; According to Van Packen, (hey assume oft^ 
^Uiesi the form of long- pointed pn'sms t i Spielman and 
^Corvious } obtained them in groups, some of them 
.'Iincc^aped, others needle- formed, others pyramidal. 
Morveau obtained them needle-form j|. Their specific 
gravity is l"5962 If. 

As they are sold by apothecaries in this country, they 
•re in groups, and appear to be very irregular four-sided 
^isms. By my experiments they are composed of 
W5 real acid and 15'5 of water. 

3. Crystallized tartaric add is white, and very firm, 
«ul is but imperfectly transparent. It may beexposed 
.lo the air for any length of time without undergoing any 
change. When heated a few degrees above 21 20 it 
melts and remains limpid and transparent like water. 
■At 230° it boils without losing its transparency or be- 
coming coloured. If the boiling be continued for a 
lihofl tine only tt does not lose above 4 per ctnl. of its 

y 



■ An*, it CUm. llvii. 1 47- 

I Emy. MtM. CUm. L .4«j. 
^ HwKnftw*. An. it CUw,. ui 



t Berg[nan,ni. ]6t. 



COUaOITnLE ACIDS. 

weight. On cooling i( concrete* agun into % h»ti h> 
tniirantparcnt mass, very much resembling ■ qu&btf 
of white sugar that has been melted at the »ine tcropc- 
nture. By this process the nature of the acid ii chlD> 
ged. h now deliquesces when exposed to the mir 

In the open fire tartaric acid buma without leaviB| 
any other residuum than a spongy charcoal, which ge> 
nei->lly contains a little lime. When distilled in dam 
vessels, ii is cnnvcrtcd inro ctrbonic acid gas and eati 
teted hydrogen gas, a coloured oil, and b reddiib aat 
liquor, which was formcrW distinguished by the 
of pyrolartta out acid, but which Fourcroy and Vuiqiwi 
lin have lately ascertained to be merely acetic acid 
prcgnated with oil *. 

Wh^ tartaric icid combined with » base, u t 
lime, is distilled in sl sufficiently strong heat, it iio 
pletely decompO!>cd. The products into which it h 
conrcTted, are, u'.jrrr, earbonicand.btavf in/laamabit 
air, oil and tbitrroal. The qunntily of carbonic acti 
which it yields it less than what is furnished by an •> 
qual weight of oxalic acid ; but it differs from oxalic 
acid, in yielding a portion ai brown coloured thick (a^ 
which hasanempyrcumHiic smell, and dissolTes in alcfr 
hoi. 

4. Tartaric acid dissolves readily in water. Ber^ 
roan obtained a solution, the specific gravity of wiiiti 
was l'230+. Morveau'bscrvcd, however, that cryfc 
tals formed spontaneously in a solution, the ipcdfie 
gravity of which was 1-084. It is not liable to Ipob 



TiJtfARie. 



SItf 

Chap. II. 



deeomposiiion wbeo dissolved in water, unles 

ition be considerably diluted. 
Neither its action on oxygen gas nor on simple 
IDmbustibles and incotnbuuibles has been examined } Action of 
knt it is probable that it is not capable of producing any di^^ ' 
lenrible change on them. It is capable of oxidizing iron 
M zinc, wid even mercury ; but it does not act upon 
indmony, bismuth, tin, lead, copper, silver, gold, nor 
platinum. Its action on the other metallic bodies has 
Icaicely been examined. 

' 6. It combineswiih alkalies, eaTibs,and metallicox- 
ides, and forms salts known by the name of tartratei, 
nough it forms with the alkaline earths salts which 
Mv scarcely soluble in water, yet it has not the proper* 
tj of precipitating any of them from their solutions. 
In this respect it differs very greatly from oxalic 
■dd, which precipitates them all except magnesia. 

7. The action of the greater part of the other acids 
on it is unknown. Hermbsladc has ascertained, that it 
may be converted into oxalic acid by distilliog it repeat- 
edly with six times its weight of nitric acid. By this 
process he obtained 500 parts of oxalic acid from 300 
jparls of tartaric acid X- 

8< From this result, and from the products obtained 
hen tartaric actd is distilled, it is evident that it is Compou' 
composed of oxygen, carbon, and hydrogen. Fourcroy *""'' 
(Informs us, that Vauquelin and he have ascertained 
' that these ingredients are combined in it in the follow- 



lN'.&/.ii/Cim 



(30 COHSVtTULS ACIDS. 



1 Book II- lO'SoxTgen 

1^ - I , ■ 10*0 CUMO 

^^^L 10*5 bydrogea 

Li 

I 

HUtOTT. 



lOP'O 

Tsrtatic acid, in s itate of purity, has fcircclj bi 
put to aoy UK i but some of the oontpouods intow 
it enters are tnuch employed m medicioe. ThU a 
bas the property of combining in two different p 
tions with a great number of bases. With poUsb, k 
iafltaDcc, in one proportion, it forma a a&It pretty mIi 
tcr, called tartrate ofpotaibi but wh«n add) 
in B greater proportion, tl forms tartar, a salt very i| 
perfectly soluble in water. By this property, the ^ 

ice of tartaric acid in any acid solution may eaul 
1w detected. All that is ncceiuiy is to drop in slo»l| 
• little solution of polash : if tartaric acid be pTCtol 
tatlBr immediately precipitates in tbc fonn of \ wfail 
gritty powder. 



SECT X. 



OF CITHIC ACID. 






Chemists have alwayi considered the juice of. 

and lemons as an acid. This juice tuniaint a 

of mucilage and water, which lenders the acid iibpan^ 

and subject to spflntaneous decompasitioit. Mi GeoT' 

gius look the following me'hod ti scparaii- 

lage. He filled a bottle entirely with lemon •juice, cerk* 



I four years tTie liquid ^^■'V- ' 



■ trt-Bfc, 

i it, ancl placed it in a cellar : ii 

'»s become as limpid as water, a quanliiy of mutiUge 
h*A fillm lo tlie boilom in the form ot flakes, and x 
lick crust had formed under ihe cork. He exposed 
fllis Bcid to a cold of ^3°, which frote a great pan of 
water, and left behind a strong and pretty pure 
*. Ii was Txheele, however, that first pointed out 
thod of obraintng this acid perfectly purCf and who 
dcmonstraied thai ii possesses peculiar properties. 

J. His pioccss, which is srtil followed, isihis : Satu> F 
Ic lemon juice, while boiling, with powdered chalk. " 
white powder falls to the boitotn, which is lime com- 
liaed with citric acid. StfparaCe this powder, and 
Snah ii with warm water till the water passes off co- 
lourless. Then pour upon it as much sulphuric atid 
as will saturate tlie chalk employed, having previouily 
diluted it with six limes its weight of water. Boil the 
mixture tor some minutes, and pass it through a filter 
to separate the sulphate of lime. The liquid is then to 
be evaporated 10 the consistence of a syrup, and set 
aside to cool. A number of crystals form in it : these 
citric acidf. 

ilr Scheelc advises the use of an excess oF sulphuric 
acid in order lo ensure ihe separation of all the lime; 
but according to Dizc, this excess i'< neces!>ary for atio* 
thcr purpose J. A quHnlity ot inucilage still adheres 
to the ciiric acid in its combination with lime, and sul- 
pliuric acid is necessary ii< decompose this mucilage | 
which, as Fourcroy and Vauquelin lave proved, il is 



• Slixlitlm Tr-. siKii, 177^ 
I N chulson'i JmrMt, ti, i|J. 



n 



COHlDSnaLE ACtDt. 

capiblc of dotQg. His proof of the preseoce of rane 
Ugc h, that when the solation of citric acid in wtu 
which be had obuuoed, wsi safiicientljr coDcentnttil I 
cvapoTation, it assumed a brown colour, asd even b 
came black towaids the end of ihe evaporation. T 
crystals also were black. By repeated solutions and 
VBporations, this black matter was separated, and fonai 
to be charcoal. Hence he concluded that mucilage 
been present ; for mucilage is composed of carbon, 
drogen, and oxygen } sulphuric acid causes the hydtt 
gen and oxygen to combine and form ivater, and cl 
coal remains behind. It isnot certain, however, ai 
Nicholson remarks very justly *, that the sulphuric! 
may not act upon the citric acid itacif, and that 
charcoal may not proceed from the decomposition of it 
at least the experimfints of Mr Dizc are insufficient I* ' 
prove Ihe contrary. In that case, the smaller the «• 
cess of sulphuric acid used the belter. 

Proust, who has published a memoir on the prcpan* 
tion of citric acid in ihe Journal de Pbyit^ttt for 1801 1, 
has observed that this is actually the case. When too 
much sulphuric acid is employed, it acts upon the citric 
acid, chars it, and prevents it from cry stalli ring. Thit 
error is remedied by adding a little chalk. This cbe- 
miat has ascertained, that four parts of chalk require far 
saturation 94 parts of lemon juice. The citrate of line 
obtained amounts lo 7t parts. To decompose Uut| 30 
parts of sulphuric acid, of the specific gravity 1*15, ire 
necessary. 

2. The crystals of citric acid are rhomboidal prisms, 



f /»»-. J, Pfy,, til j«. 



! sides of wtiich are inclined lo each otiier at angles Ctwp. IL 
aboat ] zo and CO degrees, terminated at each end by 
ir tnpeioidal faces, which include the solid angles*. 

Chey are not altered by exposure (o the air. Their 
ite is exceedingly acid, and even excites pain ; but 

rtien the acid is properly diluted with water, the acidtty 
pleasant. 

3. When exposed to the open fire, it first melts, then 
relJs up and exhales an acrid vapour, and leaves be> 
nd it a small quantity of charcoal. When distilled in 
osc vessels, it parily evaporates without decomposition, 
id is partly converted into acetic acid, carbonic acid, 
id carbureted hydrogen gas, which pass over, and 

barcoal which remains in the retort. 

4. Citric acid is exceedingly soluble in water. Ac- 
ording to Vauquelin, 100 parts of it require only 75 

of water. Boiling water dissolves twice itswtight 
S it f. This solution may be kept a long time in close 
isaelsi however it at last putrifies, and is decompo- 

i. 

5. Neither oxygen gas nor the simple combustibles 
.. incombustibles produce any effect upon it. it is ca- 
pable of oxidizing iron, zinc, tin. It does not act upoa 
|ald, silver, platinum, mercury, bismutb, sntiroony. 



0. It combinei with alkalies, earths, and metallic ox* 
ides, and forms salts known by the name of citratts. 

7. The action of none of the acids on it has been ex- Aciioa of 
untDCd, if we except that of the sulphuric and nitric. 
Sulphuric acid, when concentrated, converts it into a- 



*Ptst, NicIia(ao[i'i/«>ru/,ii. 33. 



3t4 COMBUSTIBLE ACIDS. 

Book 11. cetic acid *• Scheele said that he could not convert il 
iiriaoo .^^^ oxalic acid by means of nitric acid, as he had done 
several other acids : but Westrumb affirms, that this coa« 
version may be affected ; and thinks that Scheele hid 
probably failed from having used too large a quantity of 
nitric acid, by which he had proceeded beyond the con- 
version into oxalic acid, and had changed the citric add 
into vinegar : and in support of his opinioo, he qooiei 
his own experiments; from which it appeared tbat,lij 
treating 00 grains of citric acid with different qmh 
tities of nitric acid, his products were verj differest 
Thus with 200 grains of nitric acid he got 90 gratis 
of oxalic acid ; with 300 grains of nitric acid be ob- 
tained only 15 grains of the oxalic acid j and with 600 
grains of nitric acid no vestige appeared of the oxalic 
acid. On distilling the products of these expcrimeots, 
especially of the last, he obtained vinegar mixed with 
nitric acid. The experiments of Westrumb have been 
confirmed by Fourcroy and Vauquelin ; who, by treat- 
ing citric acid with a great quantity of nitric acid, coo* 
verted it into oxalic and acetic acids. The proportioA 
of the first was much smaller than that of the second. 

From these experiments it is evident that its compo- 
nent parts are oxygen, hydrogen, and carbon ; but the 
proportions of them have not b^en ascertained* 

The use of this acid as a seasoner of food, and in 
preparing an agreeable cooling drink, called iemtmadif is 
well known. 



• rosrcroy, ▼u. %o$. 



I^IKIC, 




SECT. XL 



OF KINIC ACID. 



pIr Deschamps^ junior, an apothecary in Lyons, some DUcofcrf. 
lime ago published a method of extracting from yellow 
Peruvian bark a peculiar salt, to which the physicians 
of Lyons ascribed the febrifuge properties of that bark. 
His process was very simple ; the bark was macerated 
in cold water, and the infusion concentrated by evapo- 
ration. It was then set aside for some time in an open 
vessel. The crystals of the salt gradually formed and 
leparatedy and they were purified by repeated crystalli- 
zations. From 100 parts of the bark about 7 parts 
of these crystals were obtained *. 

This salt has been lately examined by Mr Vauque- 
lin^ who has proved that it is composed of lime united 
to a peculiar acid hitherto unknown. To this acid he 
has given the name of iinic^ borrowed from the term 
auinquina, applied by the French writers to the bark 
from which the salt was extracted. 

Deschamp's salt then is ktnate oflimt^ It possesses Kinatettf 
the following properties. ^ 

Its colour is white, it crystallizes in square or rhom« 
boidal plates ; it has no taste, and is flexible under the 
teeth. It dissolves in about five times its weight of 



# ^u. ^ Qhim. ilTiil. X6a. 



otIUai 



120 COMBUSTIBLE ACISI. 

„?^''";, water at the tempcraiutc of 55*. It ii insoluble 

> tf < alcohol. 

When placed en burning coalt it swells, gives e 
2 smell like larUr, and leaves > mixiurc of carbonate 
lime and charcoal. The fixed alkalies and their 
D&tes precipitate lime from the aoluiioQ of this 
but ammonia produces no effect. Sulphuric 
•cid precipitAie lime likewise, but no precipiuis is pa 
duecd bj acetate of lead or nitrate of silver. The H 
fusion of tannin occasions a fljky yellow precipitate, 

SMTitim Mr Vfii.i(]iielin separated the lime from the kit 
tcid by means of oxalic acid. The oxalate of lime o 
tained from 100 grains of the salt weighed 27 graig 
Hence he concluded that the salt was a compound 
85 parts acid aud 15 lime. But the lime in 37 
of oxalate of lime very little exceeds 10 grains. Hei 
the salt ought to be composed of op parts icid aad 
of lime. 

The ktnic acid, thus freed fiom lime, was cona 
traled by evaporation to (he consistency of a syrnp, i 
then set aside for a week. No crystals formed in 
Spontaneously ; but upon being touched with a gli 
rod it wholly crystallized at once in divergent plates, 
lis colour was slightly brown (doubtless from so 
impurity) i lis taste was estrcmely acid and somew 
bitter, probably because it was not quite free frotD 
other constituents of iht^bark. It was not altered 
being lefr exposed (o the air. 

On burning coals it melted, froatbed, blackened, I 
exhaled in acrid vapours, leaving only a little clnrcffil 
behind. 

It combines with the different bases, and forms a 
ef salts called Hnattt. The alkaline and earthy ^ 




8AC&ACTIO, 

■ates are soluble and crjstallizable. This ac does 
■ot precipitate nitrates of silver, mercury, nor lead *. 

This detail, though imperfect, is sufficient to dis- 
lujuish the kinic from ever; other acid. Its decom> 
^tition bj heat shows that it belongs to the class of 
•ombastible acids. Its crystallizing, its great solubility 

10 water, and its forming a soluble salt with lime, and 
aot precipitating silver nor lead, sufficiently distinguish 

11 from all the other combustible adds with which it 
ought be coufounded. 



OF SACLACTIC ACID. 



X BIS acid was discovered by Scheele in 1180. After kk^j. 
having obtained oxalic acid from sugar, he wished to 
examine whether the sugar of milk would furnish the 
same product. Upon four ounces of pure sugar of 
milk, finely powdered, he poured 12 ounces of diluted 
oitric acid, and put the mixture ia a large glass retort, 
which he placed in a sand-bath. A violent cffcrves- 
encc ensuing, he was obliged to remove the retort from 
the sand-bath till the commotion ceased. He then con- 
tinued the distillation till the mixture became yellow. 
As no crystals appeared in the liquor remaining in the 
retort after standing two days, he repeated the distilla- 

> Am. JtCiithUt. i6i. 




MS COmOtflBU AdDl. 

tion as before, with the addition of eight oluioes of ni. 
trie acid, and continued the operation till the jdlov 
colour, which had disappeared on the addition of the ai. 
trie add, returned. The liquor in the retort conitia* 
od a white powder, and when cold waa obeenred fobs 
thick. Eight ounces of water were added to dflute this 
liquor, which was then filtrated, by which the wbtie 
powaer was separated ; which being edulcorated nd 
dried, weighed trdr. The filtrated tolntion waten« 
porated to the consistence of a syrupt and again tab* 
jected to distillation, with four ounces of nitric acidu 
before ; after which, tlie liquor, when cold, was ob* 
served to contain many small, oblong, sour crystals, to- 
gether with some white powder. This powder being 
separated, the liquor-was again distilled with more ni- 
tric acid as before ; by which means the liquor wsi 
^ndered capable of yielding crystals again ; and bj ooe 
distillation more, with more nitpc acid, the whole of 
^e liquor was converted into crystals. These crystal^ 
added together, weighed five drams ; and were found, 
ppon trial, to have the properties of the oxalic acid. 

Mr Scheele next examined the properties of the 
white powder, and found it to be an acid o( a peculiar 
natuie \ he thetefore called it the add of the sugar of 
tmlk *. It was afterwards calkd saclaetie acid by the 
French chemists. Foiircroy has lately given it the name 
of mucous acid, because it is obtained by treating gum 
fuiibic, and other mucilaginot^s substances, with oitrif 
acid. 



f 8e!.cde, u, 6^ 



8ACLACTie< 

'r Hermbstadt of Berlin had made similar experi- Chip. IL 
1 sugar of milk at ihe same time with Scheele, 
Hid with similar resulis ; but he concluded ibnt the 
^vhite powder which he obtained was nothing else than 
oxalate of lime with excess of acid, as indeed Scheele 
himself did at first. After he became acquainted with 
Schccle's conclusions, lie published a paper in defence 
of bis own opinion ; but his proofs are ver^ far from 
cstnbluhing it, or even rendering its truth probable *. 
He acknowledges himself, that he has not been able 
to decompose this supposed salt 4 he alluws that it pos- 
sesses properties distinct from the oxalic acid j but he 
ascribes this difftrence to the lime which it contains : 
yei all the lime which he could discover in 24O grains 
of [his salt was only 20 grains ; and if the alkali which 
be employed was a carbon.ite (as it probably was), 
these 20 must be reduced 10 ] J . Now Morveau has 
shown, that oxalic acid, containing the same quantity of 
lime, exhibits very difftieni properties. Besides, this 
•cid, whatever it is, when united with lime, is separated 
by the oxalic, and must therefore be different from it, 
U it would be absurd to suppose that an acid could dis- 
place itselff. The saclactlc acid must therefore be 
considered as a distinct acid, since it possesses peculiar 
properties. 

1. Saclactic acid may be obtuned by the following Piqiirv 
process; Upon one pari of gum arabtc, or other similar "°°' 
gam, previously put into a retort, pour two parts of nt- 
Uic acid. Apply a slight heat for a short time, till a 



t Morroti, £'<ji. MnM, I agl. 




iSO COMBUSTIILX ACtDf • 

little nitixms gas and carbonic acid gaa cornea ovfr; thei 
allow the mixtare to cool. A white powder gradaallj 
precipitates, which majr be easily separated hj Bstu 
tion. This powder is saclactic acid *• 

9. Saclactic acid, thus obtained, is under the totm sf 
a white gritty powder, with a slighdj acid taafe« 

Heat decomposes it. When cfistilled, there eonci 
over an acid liqnor which crystallizes in needleaa on cool- 
ing, a red coloured acrid oil, carbonic add gma|» and csr- 
boreted hydrogen gas. There remuas in the retort a 
hirge proportion of charcoal. 

Saclactic acid, according to Scheele, is aolnble m 00 
parts of its weight of boiling water; bat Messrs Hermb. 
stadt t and t Morvcau found, that boiling water only 
dissolred V^th part: it deposited aboatlf th part on cooU 
ing in the form of crystab f • 

The solution has an acid taste, and reddena the infii* 
aion of tnmsol ||. lu specific graTify, at the tempera* 
tnre of 53*7% is 1«0015 f. 

The compounds which it forma with earths^ atlr^fi fy^ 
and metallic oxides, are denominated tmcoknu. These 
salts are but very imperfectly known, no chemist ha^ 
vtng examined them except Scheele. The fiicts which 
he ascertained are the following : 

With potash it forms a salt soluble in eight parts of 
boiling water, which crystallizea on cooling. The sso* 
colate of soda also crystallizes, and is solnble in An 
parts of water. Saccolate of ammonia losea its base' bv 



* Fourcroy, tH. 146. 
t Emcyt, MtiM, L 190. 

r- 



r. 111. 




■ tTRIC. 

crate beat, while the acid [cmatns behind. The 
>uckIs which it forms with the earths are aearlj 
ble in water. It scarcely acts upon any of the 
i, but it combines with their oxides : it formt 
4most insoluble in water. When poured into the 
:s of silver, mercury, or lead, it occasioni a white 
lilate. It produces no change in the sulphates of 
:opper, zinc, manganese, nor in the muriates of 
1 mercury •, 



s<«a 



I 



OF ORIC ACID. 



lous attempts were made by chemists to ascertain ] 
tture of the calculous concretions which occasion- 
m in the kidneys and bladder, and produce one 
e most painful diseases to which we are liable. 
: attempts were atletided with very Utile succesB, i 
:heele published a set of experiments on the suba | 
I ma. He examined several of these urinary I 
i, and found them composed chie6y of a peculiar ' 
the properties of which he described. His resul 
soon after confirmed by Bergman, who had cn- 
. in a simitar set of experiments about the same 
[. To the acid thus discovered, Morveau gave a 
^^me of benoardic, which was after changed i 

^^^■^ f Ibid. L tayuid 110. Frnti Tr<» 



992 COMBUSTIBLE ACIDS. 



i»r*^"ii ^ ^i^^i^ by ^^ French chemists, when they contrivtj 
y ^ ■■> the new chemical nomenclature in 1787. This latt 
term, in consequence chiefly of the observations and ob- 
jections of Dr Pearson, has been recently laid aside, 
and the name uric acid substituted in it^ place. 

Scheele ascertained that uric acid exists always in 
human urine. Experiments on the urinary calculi were 
published by Mr Higgins in 1789 *, and by Dr Ausdn 
in 1701 ; but little was added to our knowledge of 
^ uric acid till Dr WoUaston published his admirable 
paper on the calculous concretions in 1707. Dr Pear* 
son published a copious set of experiments on the same 
subject in 1798» in which he enumerates his trials oa 
uric acidy and endeavours to prove that it is not entit* 
led to the name of acid^ but ought to be classed among 
animal oxides. This drew the attention of Fourcroy 
and Vauquelin to the subject : they published an excel- 
lent treatise on urinary calculi, in which they demoa« 
atrate that it possesses the properties of an acid, asd 
confirm the observations of Bergman and Scheele. Bot 
for the most complete account of uric acid we are en- 
dcbted to Dr William Henry, who made it the sab- 
ject of his thesis published in 1807. 
Pieptrft. 1. To obtain pure uric acid, Dr Henry dissolved puU 

^**' verizcd calculi (previously known to be composed 

chiefly of that acid) in a ley of potash, and precipitated 
the uric acid by means of muriatic or acetic acids. 
The powder thus obtained was first washed with a little 
ammonia, to remove any adhering foreign acid^ and 



^ Comparative vttw of the fblogi$tU aitd aMti^hitgbtk il fttr ktf ft ll^ 



olcoratcd wiih & sufficient quantity of i 



335 
Chap.!!. 



S. Uric acid thus obtuocd is a white powder, which properties 
icels harsh bat not grilty , and is destitute both of taste 
Ind smell. It reddens ihe infusioa of litmus. It dis- 
lolvcx in 1*120 pans of water at the temperature of 60°, 
iLDd in 1150 pans of boiling water. As this last sola- 
tioti cools, it deposites minute crystals of uric acid. 
The watery solution reddens litmus, but produces no 
precipitate when dropt into earthy or metallic salts •. 

3. It is rapidly dissolved by lised alkaline solutions, 
but less readily by ammonia. The alkaline carbonates 
have no effect on it whatever f . 

4. It decomposes ibe alkaline hydrosulpbureis, and 
pKcipiiaies their sulphur. It likewise decomposes 
apRp, provided a sujEcieni quantity of it be employed %■ 

5> It dissolves in niinc acid ; and when the solution 
is evaporated nearly to dryness, it assumes a fine pink 
colour, which becomes much deeper when vater is ad- 
ded, so as to have a near resemblance lo carmine, la 
this state it siaiiis wood, the skin, &c. of a beautiful 
IC'' colour. The watery solution of this matter loses 
its red colour in a few hours, and it cannot afterwards 
be restored {. 

When tl>e solution of uric in nitric acid is boiled, a 
quantity of azotic gas, carbonic actd gas, and of prus- 
sic «cid, is disengaged {|. Dr Pearson, by repeated dis- 
tillations, converted the residue imo nitrate o 
When oxymuriatic acid gag is made lo pass ii 



>H«rT. 



t ^^ri", ^tnraay, and Henry. 

f JMHHI mo, fcaiMTi, ind lUnif. 



p 



coMBirs-mtE ACIDS. 

containing this acid iuspcnded in it, the add atsutaet ■ 
' gelatinous appearance, then dissolves ; carbonic acid 
gai is emitted, and the solution fields by evapdratioa 
muriate of ammonii, superoralate of ammoma, mniiatic 
acid, and inaltc acid *. 

6. It combines with the different bases, uidfeniitt 
genus of sails called uratei ; for the examination of 
which we arc chiefly indebted to Dr Henry. 

7. When uric acid is distilled, about a fourth of tbe 
acid passes over altered in its properties, and is found it 
the receiver crystallited in plates ; a few drops of thidt 
oil make their appearance ; fib of the acid of coacreU' 
carbonate of ammonia, some prussiate of ammord^ 
same water, and carbonic acid pass over ; and there 
remains in the retort charcoal, amounting to aboat |tlt 
of the weight of the acid distilled \. According to Dt 
Henry, the decomposition goes on in the Ibllowiog 
manner : 1. A drop or two of water holding carbonalt 
of ammonia in solution passes into the receiver 
Dry carbonate of ammonia; 3. The ncid sublimate f 
4- The coal in the retort amounts to about ^ of the 
calculus distilled. 

The nature of the acid sublimate has been partictiUr< 
ly examined by Dr William Henry. Scheele had 
sidered it as analogous to succinic acid, and Dr Pear< 
son as approaching to benzoic acid in its properties. 
According to Dr Henry, it is a salt composed of ajt<- 
culiar acid combined with ammonia. The foUowiog 
he found to be its properties. 



L •BniinilcUi, 

I \ Fourcror, A 



it CJim. iivir. sfi;. Fiiur:ra7, t. SS*. 
Foiircrar, An. ii CUm. in. tU. 




Its colonr is yellow, and it has a cooling bitter taste. 
It dissolves readily id water, and in alkaline solutions, 
from which it is not precipitated hy acids. It dissolves 
■Iso sparingly in alcohol, tt is volatile ; and when 
lablimcd a second lime, becomes much whiter. Tlic 
watery solution reddens vegetable blues ; but a very 
imal) addition of ammonia destroys this properly. It 
does not produce an effervescence with alkaline carbon- 
Uet. By evaporation it yields permanent crystals, but 
ill defined, from a portion of animal matter adhering. 
Tbcy redden vegetable blues. Potash, when added to 
titesc crystals, disengages ammonia. When dissolved 
SD mtric acid they do not leave a red slain, as happens 
with uric acid ; nor does their solution in water decom- 
pose the earthy salts, as happens with the alkaline 
nrates : neither has it any action on the salts of copper, 
tiron, gold, platinum, (in, or mercury. With nitrates 
I of ulvef and mercury, and acetate of lead, it forms a 
I white precipitate soluble Jn an excess of nitric acid, 
il Muriatic acid occasions no precipitate jn the solution 
, of these crystals in water. These properties show us, 
[ that the add of the sublimate is different from the uric, 
I snd from every other known acid. Dr Austin found, 
that by repeated distillations it was resolved into ain- 
SDonia, azote, and prussic acid. Hence its coostitucnts 
■re doubtless the same as those of uric acid, varying 
only in proportion. 



S96 COllBUrflJltE ilCIBt. 

Booktr. 



SECT. XIV. 



OF LACCIO ACID4 



WMotf. AboiIT the year 11869 Dr Anderson of Mtdrumca* 
tioned, in a letter to the governor and conncil of thil 
place, that nests of insects, resembling small cowiy 
shells, had been bronght to him from the woods by ths 
natives, who eat them with avidity. These supposed 
nests he soon afterwards discovered to be the covering! 
of the females of an undescribed species of cocco% 
which he shortly found means to propagate with grest 
facility on several of the trees and shrubs growing 10 
his neighbourhood *• 

On examining this substance, which he called vftkt 
/ac, he observed in it a very considerable resemblsnoe 
to bees wax ; he noticed also, that the animal which 
secretes it provides itself by bome means or other uith 
a small quantity of honey, resembling that produced bj 
our bees ; and in one of his letters he complains, thst 
the children whom he employed to gather it were tempt* 
ed by its sweetness to eat so much of it as materially to 
reduce the product of his crop. Smull quantities of 
this matter were sent into Europt: in 1789, both in its 



• The Chinese collect a kini uf wlx, v^h t': tbcy cxW^'Jaf froma 
coccus, depob tci^ tor the ; urpo^ «>f bireiin^ ol « v tu Jirubs ud 
fn?nage it exucily -^ the JVicxiC4n«> m4* aji^ ;hc co hinr^l ..kect. It mf 
the ktiowleHgc ot tliii thit induced Dr Andenou to attempt to prpp* 
gate hii ioiecti 



LACCIC. iSY 

fttural state and melted into cakes ; and in 1793 Dr Chitp. \h^ 
sdrsoHy at the request of Sir Joseph Banks, undertook 
chemical examination of its qualities, and his experi- 
t«nts were published in the Philosophical Transactions 
^T 1794. 

A piece of white lac, from 3 to 15 grains in weight, 
L probably produced by each insect. These pieces are 
f a grey colour^ opaque, rough, and roundish. When 
rhite lac was purified by being strained through mus^ 
D, it was of a brown colour, brittle, hard, and had a 
ittcrish taste, it melted in alcohol, and in water of 
le temperature of 145^* In many of its properties it 
rsembles beeswax, though it differs in others; and 
)r Pearson supposes that both substances are composed 
f the same ingredients, but in different proportions. 

]• Two thousand grains of white lac were exposed in Properti«9< 
uch a degree of heat as was just suflScient to melt 
lem. As they grew soft and ff'iid, there oozed out 
50 grains of a reddish watery liquid, which smelled 
ke newly baken bread *. To this liquid Dr Pearson 
las given the name of of iaccic acid\» 
2. It possesses the following properties : 
It turns paper stained with turnsol to a red colour* 
After being filtered, it has a slightly saltish taste with 
ittemess, but is not at all sour* 

When heated, it smells precisely like newly baken hot 
tread. 



* The same Iquid appt^ars on prefting the crude lac between the 
Dgcrs; and we arc told that when newly leathered it is replete witli 
lice. 

f Pcar»on*^ TraHsl. «ftbt (ILtmUal K^menclature, 

VuL II. T 



SS^ C0MBUST7BL£ ACIXIS. 

Book IL On standine. it «rows somewhat turbid, aoddepoiiik 

Divivion !l. r -• 

a small quantity of sediMteiit. 

Its specific gravity at the temperftture of 60* i» 

A little of ir h ATI i.g being evaporated till it K^wvecy 
turbid, afforvled on st.'.nding small needle-shaped crji. 
tals in mucilaginous matter. ' 

Two hundred and fit'tj grains of it were poured isio 
a very small retort and distilled. As the liquor gmr 
\9ZTWy mucilage- like cU'uds appeared ; but asthehm 
increaNcd they dr&appeared again. At the temperatarerf 
200*^ the l*quor distilled over very fast ; a !imaU qoaatitj 
of extractive matter remained behind. Tlie distilled fi. 
quor while hot Kme^led Lke n^wly baken bread, and wu 
perfectly transparent and yellowish* A shred of paper 
stained with turn^ol, which had been put in Co the re- 
ceiver^ was not reddened ^ nor did another which had 
been i:iimersed in a solution of sulphate of iron, and also 
placed in the receiver, (urn to a blue colour upon being 
moistened with the solution of potash *• 

About 100 grains of this distilled liquid being eva. 
porated till it grew turbid, after being set by for a 
nighty afForded acicnUr crystals, which under a lens ap. 
pcared in a group not unlike the umbel of parsley. The 
whole o^ them did not amount to the quarter of a graio. 
They tasted only bitterish. 

Another 100 grains bting evaporated to dryness in 
a very low temperature, a blackish matter was left be- 
hind, wliich did not entirely disappear on heating the 
spoon containing it very hot in the naked fire ; but on 



i^C 



• A proof that ii'Jt acid wu not the pntwtc. 



: oxalic acid to a much less degree, it evapofated. Chap. If-, 

r not a trace behind. 

onate of lime dissolved in this distilled liquid with 

sceitce. The sol'ution tasted bitterish, did not 

aper stained with turnsol red, and on adding to 

3nate of potash a copious precipitation ensued. A 

f this solution of linie and of alkali being era- 

I to dryness, and the residuum made red hot, no- 

emained but carbonate of lime and carbonate of 

■ 
» 

1 liquid did not render nitrate of lime turbid, but 
jced turbidness in nitrate and muriate of barytcs* 
)00 grains of the reddish -coloured liquor obtain* 
nehing white lac, catboi.ate of soda was added till 
jrvescence ceased, and the mixture was lieutra- 
for which purpose three grains of the carbonate 
lecessary. During this combination a quantity 
:ilaginous matter, with a little carbonate of lime, 
ecipitated. Tiie saturated solution being fihra- 
l evaporated to the due degree, afforded on stand-* 
liquescent crystals, which on exposure to fire left 
residuum of carbonate of soda. 
e*.water being added to this feddish«.coloured li- 
)roduced alight purple turbid appearance; and on 
g there were clouds jusi perceptible^ 
buret of lime occasioned a white precipitation, 
sulphureted hydrogen gas was perceptible by the 

lure of galls produced a green precipitation, 
hate of iron produced a purplish colour, but no 
tation ; nor was any precipitate formed by the 
ri first of a little vinegar, and then of a little pot* 
the mixture. 

Y2 



54^ COMBUSTIBLE ACIDS. 

Book n. Acetate of lead occasioned a reddish prrdiotatiQii 
Divi nil) n. ,. . 

winch reaissoivcii on adding a Jittlc nitric uCid» 

Nitrate oi mcicury produced a whitish tur^ U. 
quor. 

Oxalic acid produced immediatelj the precipitatiimrf 
white acicular cr^^stals, owing probablj to the prcsoia 
of a little lime in the liquid. 

Tartrate of potash produced a precipitation not unlike 
what takes place on adding tartaric acid to tarcntc of 
potash ; but it did not dissolve again on adding potatL 

Such were the properties of tbitf acid discoveied bj 
Dr Pearson *• Before this acid can be admitted u i 
peculiar substance, it would be necessary to subject it 
to a more rigid ex minatioii. The quantity which Dr 
Pearson examined was by far too small to enable bin 
to obtain satistactory results. 



SECT. XV. 



OF MALIC ACIO< 



Preparf !• ■ ^^^ *^'^' which was discovered by Scheele in 
tioo. 178 f has received the name of malic acid^ because it 

may be obtained in abu dance from the juice of applet 
in which it exists ready formed Scheele has given us 
the following process for extracting it : Saturate the 
juice of apples with potash, and add to the solution ace- 



♦ Pbil, Tr0us. i794iP* 383. 



MALIC. 341 

Ite df lead till no more precipitation ensues. Wash , Char. H. 
^e precipitate carefully with a sufficient quantity of 
rater ; then pour upon it diluted sulphuric acid till the 
dixture has a perfectly acid taste, without any of tliat 
weetness which is perceptible as long as any lead re* 
nains dissolved in it ; then separate the sulphate of 
eady which has precipitated, by filtration, and there rc- 
bains behiiid pure malic acid *• 

Vauquelin has lately ascertained that it may be ex- 
racted, with greater advantage, from the juice of the 
i^mpervivum tectorum^ or common house^eek, where it 
Kzists abundantly comb*ned with lime. Tiie process 
which he found to answer best is the following : To 
the juice ot the house-leek add acetate of lime as long 
as any precipitate takes place. Wash the precipitate, 
and decompose it by means of diluted sulphuric acid in 
die manner directed by Scheele f . 

Malic acid may be tormed also by the action of ni- 
tric acid on sugar. If nitric acid be distilled with an 
equal quantity of sugar, till the mixture assumes a 
brown colour (which is a sign that all the nitric acid 
has been extracted from it), this substance will be tound 
of an acid taste; and alter all the oxalic acid which may 
have been formed is separated by lime-water, there re- 
mains another acid, which may be obtained by the fol- 
lowing process : Saturate it with lime, and filter the 
solution ; then pour upon it a quantity of alcohol, and 
a coagulation takes place. This coagulum is the acid 
^mbmed with lime. Separate it by fiitratioit, and edul- 



^ Sv/fJisb IruMt, and CreU*s ^ a«// for 1785. 
f j^, de Cbtm, xxii?. la;* 



^42 COMBUSTIBLE ACIDS. 

Hook II. corate it with frc.^h alcohol ; then dissolve it indii^lld 

Divi^iiOii If. . All Ml • . 

^ _,_ ' water, and pour in acetate ot lead till no more preapu 
tatioii ensues. The precipitate is the acid combiiicd 
with Icady trotn which it may be separated bj diluted 
sulphuric acid *. 

Buuillon La Grange haslarelj endeavoured to prove, 
that this acid is uotliui^ else than the acetic combiDcd 
with a peculiar vegetable matter. He has shown that 
acv.tic acid exists in the juice of apples, and thinks he 
has proved that nitric acid forms with sugar a peculiar 
e«c(rucii\e stuiT wiiich exists also in. tpples f • Buihii 
observations do not appe.ir to me to prove the coino. 
dence between acetic and malic acids, as they possess 
properties so very difleicnt from each other. 
Properties. i>. Malic acid, thus obtained, is a liquid of a reddish 
brown colour and a very acid taste. When evapora. 
ted it becomes tliick and viscid like a mucilage or sj- 
rup, but It docs not crystallize. When exposed to adry 
atmos}>hcre in thin layers, it dries altogether, and aw 
sumes the appearance of varnish. 

W^tien heuied in the oy.Qn liie it becomes black, swells 
lip, exhales an acrid fume, and leaves behind it a lery 
vohiiiiiiM/Us co.il. Wiicn distilled, tiie products are aa 
aciJ waier, a little carbureted hydrogen gas, and a large 
proportion ofcarboi.ic acid J. 

3. his very soluble ia water. It gradually decom- 
poses spontaneously, by undergoing a kind of fermenta- 
tion in the vessels in which it is kept. 

4* Sulphuric acid chars it, and nitric acid converts it 



* Srvr/is.'.' 'Irtttt, and Crel '•« Annali for 1 7 85. 

f CJthicii'o Jeut, 2U 5ufc*. ii, 173, I Fuurcriiy, vii. 199. 



ITALIC^ S4S 

into oxalic acid *• Hence it is evident that it is com* ^^P* ^* 
posed of oxygen, hydrogen, ai.d carbon, though the . 
proportions of these substances have not been ascer- 
tained. 

Malic acid combines with alkalies, earths, and me- 
tallic oxides, and forms salts known by the name of 
miilat€i. 

T- is acid bears a strong resemblance to the citric, 
but differs from it in the toliowiug particulars : 

!• The citric acid shoots into &iv cr^SiaU, but this 
acid does not crystallize. 

2. The salt formed from the c trie acid with lime is 
almost insoluble in boiling water ^ whereas the salt 
made with malic acid and the same basis is readily so* 
lable by boiling water* 

3. Malic acid pitcipitates mercury, lead, and silver, 
from the nitrous acid, and also the solution of gold uhen 
diluted with water i whereas citric acid does not alter 
any of these solutions* 

4. Malic acid stems to have a less affinity than citric 
acid for lime; for when a solution of lime in the for- 
mer acid is boiled one minute with a salt formed from 
volatile alkali and citric acid, a decomposiiion takes 
{dace, and the latter acid combines wiih the lime and is 
pirecipitated. 



^ Scbocle aod Hermbttsdt. 



544 COMBUSTIBLE ACIDS. 

Book IT. 

Diviiiinn If. ' —————— 



tiOD. 



SECT. XVI. 



OF SUBERIC ACID. 



Historr. ^ORK, a substance too U'ell known to require any de. 
scription, is the bark of a tree which bears the uik 
name. By means of nitric acid, Brugnatelli converted 
it into an acid *, which has been called the subiricadi, 
from suiir, the Latin name of the cork tree. Severil 
chemists affirmed that this acid was the oxalic, bectuie 
it possesses several properties in common with it. These 
assertions induced Bouillon La Grange to undertake t 
set of expcrimtnts on subiTic acid. These experiments, 
which have been published in the 23d volume of the 
jlnnales de CLimie, completely establish the peculiar na- 
ture of suberic cid, by siiowing that it possesses pro* 
pcrtics different from those of any other acid. 

Prcpara. ]• Subeiic acid may be formed by pouring six parts 

of nitric acid of the specific gravity l'2dl on one part 
cork grated down, or simply broken dow^ into small 
pieces, and distilling the mijcture with a gentle heat as 
long as red vapours continue to escape. As the distil* 
laiion advances, a yellow mutter like wax makes its ap* 
pearance on the surface of the liquid. While the 'mat- 
ter contained in the retort is hot, it is to be poured into 
a glass vessel, placed upon a sand-bath over a gentle 
tTre, and constantly stirred with a glass rod. By this 



« Crcli'i Anna.'j, 1,^7. 



irans it become* gradualiy thick. As soon as white 
■pours, exciling a tickling in tlic throat, begin lo 
tsefigage themstlves, the vessel is removed from ihc 
aih, and the mass coitiinudlj slirred till it is almost 

did. 

B)r this means an oranj^-coloured mass is obtained 
f the consistence of honey, of a strong and sharp odour 
rhite hot, but having a peculiu aromatic smell when 
old. 

On thi% mass twice its weight of boiling water is to 
c poured, and heai applied ttli it becomes liquid ; and 
hea that part of it which is insoluble in water is to be 
Bparated by filtration. The lilrered liquor btcomes 
inddjr; on cooling it dcpoiits a powdery sediment, 
od a ihio pellicle forms on iis surface. The sedimenB 
1 to be separated by filtration, aud the liquor reduced 
I ■ dry mass by evaporaiing in a geulle heat. This 
lass is tuheric acid. It a sLiU a little coloured, owing 
1 some acddental mixture, from wliich it may be pu- 
i6ed either by saturating it with potash and prectpila- 
tng !l by means of an acid, or by boiling it along with 
barcoal powder. 

2. Suberic acid thus obtained is not crystal liiablc, I 
ut when precipitated from potash by an acid it as- 
umes the form of a powder ; when obtained by evapo- 
aiion it forms thin irregular pellicles, 

3. Its taste isacid and slightly bitteri and when ilii. 
ttlvcd in a small quantity of boiling water it acts upoti 
lie throat, and excites coughing. 

It reddens vegetable blues; and when dropt into 
solution of indigo in sulphuric acid (Ajcirf hlue, as it 
I called in this country), it changes the colour of the 
olution, ai]d renders it green. 



• « 



S4tf COMBUaxiBLS ikCIDS, 

BomIl n. 4. Water at the tempi racure of 60* or even 10^ dis. 

solves^ only ^{..^ j)ai i of iu weight ot suberic acid ; and 
if the acid be very pure, only t7t^^ P^^^ * boiling wa. 
ter, on the conirary, dissolves half its wei^^ht of it. 

Witen expose)., lo the an, it attracts moisture, t:sp(. 
ciali^ it it be inipuie* 

5. When tx^^used to the light of day, it becomes at 
last brown ; and this tiFvCt is produced much soo:.er bf 
the direct rays of the sun. 

^Viien heated in a matrass, the acid sublime^ and the 
inside of the glass is bui rounds. d with zones of differeDt 
colouis* If the sublimaiiun be stopt at the proper 
tioie, the acid is obtained on the sides of the vessel in 
small points formed of coi.centric circles. When ex* 
posed to the heat of the blow- pipe on a spoon of plati* 
num, it first melts, tiien becomes pulverulent, and at 
last sublimes entirely with a smell resembling that of 
distilled oil. 

It is not altered by oxygen gas :— the other acids do 
not dissolve it completely. Alcohol developet an aro> 
raatic odour, and an ether may be obtained bj means of 
this acid. 

It converts the blue colour of nitrate of copper to a 
green ; the sulphate of copper also to a green; green 
sulphate of iron to a deep yellow ; and sulphate of zinc 
to a golden yellow. 

It has no action either on platinum, gold, or nickel; 
but it oxidizes silver, mercury, copper, lead, tin, iroo, 
bismuth, arsenic, cobalt, zinc, antimony, manganese, 
and molybdenum. 

6. With alkalies, earths, and metallic oxides, it forms 
compounds known by the name of suherates. 



FORMIC* . 34Y 

C1itp.IL 



SECT. XYlL 



OF FORMIC ACID. 



s acid is first . mentioned in the Philosophical Hi^oiy* 
sactions for 167 1» in a paper bj Mr Raj, giving 
xount of the observations of Mr Halse, and the ex* 
aeuts of MrFisher^ on the acid juice which is spon* 
»uslj given out by ants, and which they yield when 
led *. Mr Fishtr compares this liquor with vine- 
but points out some difi^rencet between them, 
rely any addition was made to these facts till Mar» 
published a disstrtation on the subject in the Ber* 
lemoirs for 1749, in which he describes the me« 
of obtaining the formic acid from the forimca rtt^ 
r red ant^ and points oat its properties with his 
i precision and method f. A new dissertation was 
ished on the same subject by Messrs Arvidson and 
n in 1782, in which the discoveries of Mar^raff 
confirmed, and many new particulars added. 

r 

abstadt's paper on the same subject appeared in 
i's Annals for 1784. His researches were directed 
ly to the purification of the formic acid. He de« 
itrated that the juice of ants contained several fo« 
. bodies, and among others, that a portion of malic 
might be detected in it. Richter published expe« 
iits on formic acid about the year 1703, pointing 



PUl. Tr.:nj, v. 3063. t Maiyiifi 0/«/*. i. Spf. 



348 COMBTTSTIBLE ACIDS. 

Bot>k n. out ft method of procuring it in a very concentrate! -^.. 
__ State*. Dcyeux soor attcr examii ed ft, a-^d fourd n My,- 

analn^ous to the acetic 'icid+. This o.^niun of the l^.o : 
Frt'nch ciiemisi was copfntptdin 1802 by Fonrcroyand Mirx\ 
Viuquelm who published a disseitatior on ar.rs, H IrJ^ 
coi eluded fioni their ex,.erimet.ts, t^n* tl c Wm'CiLi Ijt^' 
is nothing else than a Mixture cf the acetic and itii\% ^^?'' 
acids J. The opinion maintain- a by these celebrated 
philosophers induced Sucrsen to •- .:iinine the subjtobj 
ex|>eriment. This cltemist, in :ti. elaborate disscrtdtioa 
OD tormic acid, published in 16C:' •$, shows that most ot 
Jihe facts pointed out by Fourcr<y and Vauquelin had 
been already ^iscertained by pic.^aing chemists ; tlm 
the experintents which they detail were not sufficient lo 
warrant their conclusions ; that formic acid when pro- 
perly prepared contains no malic acid ; and that it pos- 
sesses properties different from the acetic. These con- 
tusions have been farther confirmed bj the experiments 
of Gehien ||. 
y The simplest method of procuring formic acid in a 

state of purity is that of Margraff as corrected by Rich- 
ter. Suerscn accordingly had recourse to it. This me^ 
thod is as follows : Iniuse any quantitj of ants in t- 
bout thrice their weight of water, put the mixture into 
a silver or tin coppered still, and draw off the water 
by aistillation as long as it continues to come over with* 
out any burnt smell : for the distillation must be stop- 



• Gchlcn, iv. 7. 

f Fourcru)', i. 491. Enj:. trans. I have rot leeo cither the diiim>> 
cioD ol KichCcr 01 Deycux« 

tP .M.,. % 1 Z. { Gclilcii'i /•i.r. ir i. 



^ 



roKMIC. S\t} 

I as w»on as that smell begins to be perceived. Sato- Clnp. ii. 

Bihe water inlhc receiver with carbonate of potash, and 

iporate to dryness. Mix the white mass thus ob- 

scd with as much sulphuric acid, previously diluted 

|li iu weight of water, as is sufBcienl to satutaie the 

!Bsh. Introduce the mixture into a ritort, and distil 

fc»ly to dryness. The liquid which cnmes over into 

I receiver i» to be a^ain rectified by a very modcrsito 

il, to get rid of any portion of sulphuric acid that 

\T be present. It is now punjormic acid. 

TorTnic acid thus procured is colourless like water. Propcnlu 

raonoi couiain malic acid, because ibai acid cannot be 

tilled over alon^ with water. 

[l3 smell is peculiar, and Vrry d'lffereni from thai of a. 

icacid. lis taste i-aod. I. reildens vegttable blaei. 

Its specific gravity vaiies from I-IOJ to I'M^i 

lereai the most concemrared ^cdicacidis only I-OSO. 

It does not appear susceptible of bring brought lo the 

Ic of crystals; at le^^t Lowiiz ailttnpTed in vain Id 

hibii 11 in that state, though he succeeded le^dily with 

Mtc acid. 

Notwithstanding its greater speciSc gravity, it isca- 

,ble of neutralizing much less of alkaline bodies thait 

t0e acid, as appears from the following trials of 

Unen. He reduced formic and acetic acids, each lo 

B Specific gravity 1'0525, and ascertained how much 

rfaonate of potash, carbonate of lime, and carbonaic of 

ignesiR, the same weight of each of these liquids was 

iMibIc of neutralising. The result may be seen in tbo 

Uowing little Table. 

, Fuimie Acid Acetif Acid. 

Potash 3<IA*a 465-1 

Lime 16S 231 

Magnesia 1 5U 313 



S50 



COMBUSTIBLE ACIDS. 



Boftk 11. 
DivUiofi II. 



Ana1o(^ 
with acetic 
aciJ. 



Such arp the differences between the formic and acetie 
acids pointed out by Suerson. In other respects there 
appears to be a striking analogy between the two acids, 

Both of them form sohibic compounds wirh all die 
alkalies and alkaline earths. They precipitate no me- 
tal from its solution, and of coarse form likewise so. 
luble compounds with all the metallic oxides; but there 
IS one striking difference pointed out long ago bj Mr 
Fisher, which has not been noticed by any modem die- 
mist. It is this : Acetate of lead when distilled yieUi 

m 

no acid liquor whatever ; bat formic acid may be ob- 
tained from formate of lead precisely as acetic add is 
procured from acetate of copper. 

Upon the whole, thouj^h the experiments of the Ger- 
man chemists are sufficient to separate the formic aod 
acetic acids, their analogy in other respects is so great, 
that farther researches are still requisite to elucidate the 
subject: Above all, an examination of the salts which 
the formic acid forms with the different bases ought to 
be undertaken, in order to ascertain whether formic 
acid may not be a combination of acetic acid with some 
unknown body. Gehlen indeed affirms that the form- 
ates differ from the acetates, and instances the formate 
of copper, which he says is a blue salt crystallizing ia 
cubes. 



SECT. XVIII. 



GENERAL REMARKS. 



1. The preceding Sections of this Chapter contain as 



CENCKAL REIIAIUCS. S3I 

ICcount of all the acids at present known, except five ; Oh«|> IL^ 
Mrhich for obvious reasons have been referred to other Acid 
pmrts of this Work, The first three of these will be 
described in the following Chapter. The other two^ 
Munely» the rosacic and amniotic^ are never employed 
as instruments of analysis. Tlieir acid characters are 
mmbignbus, and their properties have been but imper* 
fectly investigated. It appeared better, therefore, to re* 
serve theni till we came to treat of those animal sub^ 
ttaoces \v\ which they are found. 

2". Several acids usually described by chemists will Aci^dr 
not be found in the- preceding Sections, because their ^^ 
peculiar nature has been destroyed by the more precise 
invevtigation of modern analysis. The most re]iiark«> 
able of these acids are the five following. 

I. Lactic Acid. 

When milk is kept for some time it turns sour. 
Scheele examined the acid thus evolved, and gave it the 
name oi lactic acid. He directs the following method 
of procuring it. 

£vaporate a quantity of sour whey to an eighth Prqws- 
part, and then filtrate it : this separates the cheesy 
part. Saturate the liquid with lime-water, and the 
phosphate of lime precipitates. Filtrate again, and 
dilute the liquid with three times its own bulk of wa- 
fer y then let fall into it oxalic acid, drop by drop, to 
precipitate the lime which it has dissolved from the 
linne-waterj then add a very small quantity of lime- 
water, to see whether too much oxalic acid has been 
sidded. If there has, oxalate of lime immediately pre- 
cipitates. Evaporate the solution to the consistence of 



352 GEVERAL REM AttS. 

Book ir« honey, pour in a sufficient quantity of alcohol, aod Hi* 

Dmsion IF. ^ , * "^ . 

» 1^ I trate again ; the acid passes through dissolved in the iL 
coholy but the sugar of milk and every other substuue 
remams behind. Add to the solution a small quantitf 
of water, and distil with a small heat ; the alcohol paui 
es over and leaves behind the lactic acid dissolved is 
ix'ater *. 

From the properties of the acid procured by this 
process, Scheele concluded that it was very analagoot 
to the acetic, but tliat it wanted something to briag it 

that state. He even pointed out a method of pro* 
curing vinegar from milk in considerable quantitji 
and ascertained that it always yielded a little whes 
distilled f. 

From the recent experiments of Bouillon La Grange^ 
we learn that the lactic acid is not a peculiar acid, bnt 
a mixture of the following substances : 1. Acetic acid; 
2. Muriate of potash ; 3. A little iron ; and 4« Anaoi- 
xual matter J. 

II. ZooKic Acid. 

When animal substances and those vegetable priod* 
pies which possess similar properties aie distillea, the 
product contains an acid liquid, which Berthollet cno. 
sidered as peculiar, and called xoonic ;icid. 

To obtain it, he mixed lime wirh the distilled liqaid, 
evaporated nearly to dryness, then diluted and filtered. 



• Schfclc, Stockholm Train. xySo. f Scheele, il 66 • 



dXKkRAL kEMARKS^ 853 

»horic acid was then added, and the mixture dis- ^Chip.n. 

The receiver contained the zoonic acid *• 
tn the more recent expq^ments of Thenard, we 
that this supposed acid is no other than the ace- 
•Iding in solution a peculiar animal matter resem^ 
oilt. 

III. pTROMUcous Acid. 

lEN sugar and other sweet-tasted substances are 
sd, among other products there is always a nota- 
lantitj of an acid liquid. This acid, when recti* 
btained the names of syrupous acid, and afterwards 
uctms acid. It is now known from the recent ex* 
ents of Fourcroy and Vauquelin, that this acid is 
ig else than the acetic, holding in solution a por- 
f empjreumatic oil X* 

: V. Pyrolignous and Ptrotartarous Acids. 

SEN wood is distilled in close vessels, it alwajs 
; more or less of an acid juice : the same remark 
!S to the salt called tartar. These liquids were 
guished by the name oi pyrolignous and pyrotarta^ 
icids : but they are now known to be only the ace« 
iguised by the presence of a peculiar oil $. It is 
r to observe, however, that Gehlen has lately 
,ed that the last of these acids is quite different 



« Ann. dc Cllm, xxvi. 86. \ Ibid, iliii 176. 

\ lbi<l. XXXV. 131 

{ Fourcroy and Vauquelln, Ann., dt. CMm, xxxT. 131. 

w. //. z 



CENKKAI. XEHAIKI. 

trom Ike aoetic. When creun of tartar ii diitilLcd, j 
yields an acid liquor, which, b^ proper conce 
depoiites brownish crysuli constituting an ircid «U 
cannot be acetic, aud u hich difTers equally froa thflj 
laric*. 

3. The acids at present known, not reckoiung d 
which Temain to be described, amount to 34. Of ika 
one, the muriatic, potscsses the characters of a pa\ 
substance ; seven arc products of combustion, t 
nine supporters cf combustion. The remainiif 
arc combustible. Oxygen is essential to the add 
of (he products and supporters. The combustible « 
almott all contain it ; but it cannot be shown to be 
seniial to their acidity. Ii has been usual v 
mt«t» to divide the combustible acids into vcgetabki 
animal, because most of them are obtained from 
vegetable and animal kingdoms. Several of tbto) 
acids have been denominated mineral for ■ similar: 

SOD. 

4. Let us take a general view of all the acids, in 
der to ascertain in what degree each of them pMH 
those properties which are usually considered as i 
raclerising acid bodies. Th<;se properties are, I. 
acid taste i 2. Tiis power ototaxvtVMg vegeiableb 
into red j 3. Solubility in water i 4. Ttie properif 
forming salts. 
* All the acids have a sour taste, except the 

tic, the lungstic, ihc columbic, and the uric. In teri 
the acidity is mixed, and even almost concealed, by ni 
other more powerful lasie. But this will be best uai 
stood by inspecting the following Table. 

• An. A aim. U, 79. ' 



WWHIiiT IfWIMt 



$5S 



THte. 



IC 



ibic 



onatic 



uc 



cylic 



ic 
>dic 

ff 

lie 



«» 



None 



Hotf ftcnd 



horic 

ic 



Astriogent 



Acid, as- 
tringent 



Acid, me- 
Ullic 



AtlilL 



Solphoric 

Phosphoric 

Phosphoroat 

Nitric ^ 

Muriatic 

Flaoric 

Acetic 

Oxalic 

Tartaric 

Citric 

Kinic 

Malic 



Add, bitter 



AcidySttlph. 



Carbonic 

MeUitic 

Sebacic 

Saclactic 

Formic 



Itee. 



Acid, 



Acidy weak 




ML the acids are destitute of smell excepting the 
ing: 



Addi. 


SmelL 


ulphurous 


Sulphureous 


Phosphorous 


Phosphureted hjdrogen 


tfuriatic. 




^ooric 


Muriatic acid 


)x7muriatic 


Aqua regia 


Ijperoxjmuriatic 


Nitrous gas 



Oiattt 



Za 



$56 



(JEKtRAL IXMAACS. 



Book IT. 
DiTition If. 



Acidi. 


SmdL 


Nitric 




Acetic 


Vinegar 


Succinic * 

• 


Distilled nutgalls 


Camphoric 


Saffron 


Benzoic * 
Moroxylic 


Benzoin 



Action on 

iregetible 

bluet. 



Solubility in 
water. 



Carbonic acid, though a gas, has no smdl wkatevtc 

6. All the acids convert vegetable blues to red; tat' 
thej differ exceedingly in the extent to whieh they poii 
sess this property. The greater number convert d- 
most all vegetable blues (except indigo) to red} whik 
some, the carbonic, for instancCf only act upon the mot 
delicate, as the tincture of tumsol. The cause of Abl 
change of colour has not been ascertained. In muj 
cases it seems to be in consequence of the saturadonoC 
an alkaline or earthy substance vhich was previooslj 
combined with the colouring matter. This is the case 
evidently with respect to litmus. If this held alwajs, 
the conversion of vegetable blues into red would be 
merely in consequence of the affinities between acids and 
alkaline bodies, and of the superior taSnity which thej 
have for them. 

7. All the acids are soluble in water ; but in this re- 
spect also they differ exceedingly from each other. Two 
of thtm are so soluble in water, that they have never 



• In these two the odour U accidental, and owing to an oil. 



^ QIVEKAL REMARKS. SSI 

1 obtained except ia combination ivith that liquid. ^Chip»IL 
;se are^ 

1. Sulphuric, 

2. Nitric. 
s rest may be obtained either in the state of gas, or 
a solid or crystallized form. Six of them are 
es, which are readily absorbed by water to a certain 
Dunt ; after which the water being saturated, refuses 
ibsorb any more. The weight of each absorbed by 
) parts of water may be seen in the following Table. 

1. Muriatic 54*6 

2. Sulphurous O'lS 

3. Carbonic 0*18 

4. Oxy muriatic unknown 

5. Hyperoxymuriatic....«.unknown 

6. Fluoric unknown 

lie weight of the remaining acids, when solid or 
(tallized, soluble in 100 parts of water, is exhibited 
le following Table. 
Phosphoric 



Phosphorous 1 



Accti Very soluble, proportion 

f not determined. 
Tartaric 

Malic 

Arsenic » ••••» «....152 parts 

Citric 133 

Oxalic 50 

Boracic • 1*0 

Saclactic • 1*0 

Succinic • 1*0 

Suberic. ••••••.• 0*7 

Camphoric ••■•• 0*5 



BocikIL Benzoic O'i 

T_ , ' Mol)bdic 0-1 

All the acidx axe more or leas soluble in kItoba),a 
ccpl pliogphcric acid and the metallic acids. Tlit i 
pburic, tiilric, and oijmuriatic, as we ahall w 
wards, have the property of decomposing atcohoL 

8. AU the acids are capable of combimog wii^A 
lies, nrchs, and metallic ax idea, and of forming « 
them compounds known by the i 
subwancc wnicli wants thi* property ought lobcM 
lirfcrcd as an 
Combina- g. The two first classes of acids, as far at it k 

■Uwl^ 4n* at present, arc move simple than the third J atihitd 
""^ belonging to them contain only two ingredieDtioi 

whereas the combustible tcidt. contain three ora 
Compoji- four constituent \istJts. These last are cnmposedd 
of oxygen, liydrogeni and carbon. Heoce (hiq 
■en that several of itiem may be converted into a 
by the aciion of nitric acid. This acid alien A 
portion of liieir ingredients either by Lbtiraciiiig p 
of their carbon and hydrogen, or by ccRiinuDiaai>| I 
oxygen, or by both together. But ii is impossible to I 
explain precisely vhat these changes actually a 
to, without being acquainted with the component jam I 
of every combustible acid, the manner in which thttc I 
component parts are conbinetl, and ibe ef!iniiies«hidi | 
exist between each o( ihtm. This, however, is verj | 
fat from being the ca&e at presefli. Tl)i>ugli a vast n 
ber of experiments have been made on purpose to throw 
light on this very poiol, the difnciiltica wbich were ta 
he enconnlered have been *o great, that no accurate re- 
sults have yet been obtained. All thai is known st 
present is an appioximatiou towards the componct: 



OmtRAL REMARKf. 



ssa 



ree acids. This may be seen in the follow- ,Qi»^nj 



Acids. 


Oiygen. i 


Carbon. 


Hydrogen* 


Lcetic 
Oxalic 
*artaric 


50-19 

04 

70-5 


35-87 

32 

IS 


11*94 
4 
10*5 



le time ago ^apposed by chemists, tha each 
icids was composed of a peculiar compound 
dical, combined with oxygen. The radical 
sed to be a combination of carbon and hjrdro- 
no proof whatever has been given of the 
is opinion, nor has the smallest evidence been 
;hat any such radicals exist. It is much more 
bat all the ingredients of the acids are com* 
ther, and constitute a triple combination. 






360. : CQLQRiriC ACIM* 

B^ n. 

Dttuioii IL 



CHAP. m. 



OF COLORIFIC ACID9. 



Under the name of colorific acids (till some more^ 
propriate appellation occur), I include three bubsunces, 
which po»ess such analogous properties that thej 
ought to be classed together. As chemical bodies, tliej 
are all applied to nearly the same purposes ; nainely,^ 
to detect the presence of metallic bodies, and to sepantc 
them from other substances. They act with great coergj 
upon the metallic solutions, and at the same time prcd- 
pitate them in powders remarkable for the inteniitj 
and variety of their colours. It was this circumstance 
that induced me to apply to them the epithet colorific. 
Two of these bodies, namely, />n//^»f and gallic acidi, 
have been long considered as acids by chemists ; though 
the second docs not seem capable of neutralizing alkt- 
lies, and therefore is scarcely entitled to the name. A 
third of them, sulpbitreUd hydrogen, has been shown bj 
BerthoUet to act as an acid ; but the compounds whicb 
it forms with alkalies are only transient. Its import* 
ance depends upon the energy with which it acti 
upon metallic bodies. Along with these three acids I 
class a fourth substance, tannin, which, .ihough not 
an acid, is applied to the same purposes as the other 



COLORIFIC ACIDS. 361 

three. Indeed it would be difficult to assign any reason ^Chtp. Ilf. 
for giving the title of acid to gallic acid, which would 
exclude tannin. Upon the whole, perliaps, it would be 
better to distinguish these bodies altogether from the 
acidsy and to assign them a peculiar name of their own. 
In describing them, it may be proper to begin with the 
body in which the acid characters are best marked, and 
to terminate with that in which they can no longer be 
perceived. With this view they may be arranged in 
the following order : 

1. Sulphureted hydrogen 

2. Prussic acid 

3. Gallic acid 

4. Tannin. 

These bodies may be distinguished by the following 
characters : 

1. They unite with alkaline bodies, but are all inca« 
pable of neutralizing them except the first ; and the 
compound which it forms cannot be exposed to the air 
without decomposition. 

2. They act with great energy upon metallic solu* 
tions, usually entering into combination with the oxide, 
and precipitating it in the state of an insoluble powder. 

3. They have a tendeucy to enter into triple com- 
pounds with a variety of bodies, especially metallic ox- 
ides and alkalies ; excepr the sulphureted hydrogen, 
which is commonly decomposed by metallic solutions. 



M2^ COLO&iriC ACIDi* 

BooklL 



SECT. I. 

or tULraVKBTBD HTMlOOBir. 

This tubsttiice forms the liok by whicb the eobiiir 
acids are joined to the acids strietlj so called. Tli 
Germans have given it the naoie of fyJroMomc mL 
llie method of preparing this sabstaoce^ and the moit 
remarkable of its properties, have bees detailed ins 
preceding part of this Work *• As an instnuncat of 
chemical analysis it is usiially employed in two stalei. 
1. Dissolved in water ; in whidi state it is called Afstf 
sulfbureted byirogm. 2. Combined with alkalies bj 
causing a current of sulphureted hydrogen gaa to ps0 
through an alkaline solution till the liquid refhses ts 
absorb any more. The liquid is then heated^ to ezpd 
the excess of gas. In that state the compoond ia caBcd 
an altaline bydrosulpbunt. 



SECT. II. 



or rRuuic acis. 



WftnTj. ^Vk are indebted to an accident for our knowledge of 
this important substance. About the year 1710 Dies- 



• See VoL L p. 89. 



rxustic. 



K-a preparer of colours in Berlin, wishing lo pre- Clitp. m 
Bomt lake by precipiiating a decoction of cochi- 
neal, alum, and green vitriol, with potash, borrowed 
some alkali for thai purpose from Dippel. This che- 
mist was ihe discoverer of a peculiar animal oil which 
goes bj his name. He prepared it from blood; and the 
alkali with which he tumished Dicsbach had been em- 
[dojed in ihe process. Instead of the red precipitate 
which he expected, a beauriful blue powder fell to Ibe k 
bottom. On mentioning the circumstance to Dippel, ? 
that chemist ascribed the formation of the powder to 
the action of his alkali on the alum and vitriol. It is 
not unlikely that he had calcined the potash together 
with a portion of blood. Be that as il may, he succeed- 
ed in discovering a method of procuring the blue pow- 
der at pleasure, and it was announced as a pigment in 
Ibe Berlin Miscellanies for 1710. The preceding his- 
tory, however, was only commnaicated to the public by 
Stahl 2D years after *. 

This powder was called Pniitian blue ,- and the me- 
lliod of procuring it remained concealed, because it 
bad become a lucrative article of commerce, till Dr 
Woodward published a process in the Philosophical 
Transactions for n24, which he had procured, as he 
informs us, from one of his friends in Germany. This 
method was as follows : Detonate together four ounces P"r«a- 
of nitre and as much tartar, in order to procure an ex- 
temporaneous alkali ; then add four ounces of dried 
bullock's blood i mix the ingredients well together, and 
put them into a crucible covered with a lid, in which 






* 



36 \ COLOJliriC ▲CIDS. 

Book II. there is a small hole ; calcine with a moderate fire till 
the blood emits no more smoke or flame capable of 
blackening any white body exposed to it ; increase the 
fire towards the end, so that the whole matter cootaiiMd 
in the crucible shall be moderately but senaiblj red. 
In this state throw it into four pounds of water, and bd 
it for half an hour. Decant oflf this water, and cootiiHie 
to pour on more till it come off insipid. Add all these 
liquids together, and boil them down to four pounds. 
Dissolve an ounce of sulphate of iron in half a pound of 
water, and eight ounces of alum in four pounds of boil> 
ing water : mix all the three solutions together while 
boiling hot. An efiervescence takes place, and a pow- 
der is precipitated of a green colour. Separate this pre- 
cipitate by filtration, and pour muriatic acid upon it till 
it becomes of a beautiful blue ; then wash it with wa- 
ter and dry it*. 

Different explanations were given of the nature of 
this precipitate by different chemists. Mr Brown im- 
mediately repeated the process of Woodward, ascer- 
tained that other animal substances, VLnbeef, may be sub- 
stituted for blood ; tliat the alum is useful only to dilute 
the colour ; and tliat the blue pigment is produced by 
the action of the alkali (altered by blood) od the iron 
of the vitriol. He ascertained, too, that prussian 
blue is insoluble in muriatic acid, and that the green 
colour is owing to a mixture of prussian blue and oxide 
of iron, and that the muriatic acid developes the blue 
colour by dissolving the oxide of iron f. 

These facts were of considerable importance ; but they 



« r.''i/ Tram, xxxiii. 15. f Ibid. 1 7«4. xixlii. 17- 



w 



^ 



llirew no lighl upon ihe theory of the process. An es- Clur. 1», 
(ilsnation of this was first aiteiDpted by Gcoflroy, who 
had ascertained that any animal body whatever might 
be flubstituted for blood. According lo him, the blood 
communicates a portion of inflammable matter, or phlo- 
giston, lo the alkali, and this inflammable matter revives 
the iron of the vitriol and brings it to the metallic state. 
A greater quantity of blood, by increasing the infiam- 
nable matter, will enable the alkali to revive still more 
of the iron, and thus to strike a blue at once, instead of 
a greeu *. Though this explanation was approved of 
at the lime by the best chemists, it was far from saiis- 
facioryt. Macquer soon after proceeded, by way of 
experiment, and added a new step to the facts ascertain- 
ed by Brown, 

Tliat celebrated chemist ascertained the following Esjitri- 
facls : 1. When an alkali is added lo a solution of iron Maciiutr. 
in any acid, the iron is precipitated of a yellow colour, 
aod soluble in acids -, but if iron be precipitated from 
an acid by an alkali prepared by calcination with blood 
(which has been called a pnissian alia/i'), it is of a 
green colour. 2. Acids dissolve only a part of thii 
precipitate, and leave behind an insoluble powder which 
is of an intense blue colour. The green precipitate 
therefore is composed of two difltrent substances, one 
of which is Prussian blue. 3. The other is the brown 
or yellow oxide of iron ; and the green colour is owing 
to the mi.'dure of the blue and yellow substances. 4. 
When beat Is applied to this prussian blue, its blue co- 
lour ii destroyed, and it becomes exactly similar tocom- 



^9m 



» 



COLORIFIC ACIDS. 

mon oxide of iron. It ii composed therefore of im 
smd some oiher subttance, which heal has ihe ptopeitj 
nf driving nff. 5. If it be boiled with a pure alkili, 
it lo9c« its blue colour also, andai tlie sune time thcil. 
Lali acquire* the property of [rrecipiiatiiig of a blue a- 
lour solutions of iron in acids, or it has become 
cisely the same with the prunian alkali. 6. Pniiiin 
blue, therefore, is composed of iron and loinethiat 
which a pure alkali can separate from it, lometbing 
which has ■ greater affinity for alkali than for irin. 
*]. By boiling a quantity of alkali with prusiion blot, 
it may be completely saiurated wiih this somelhinp, 
which may be called colouring mailer, and then posK»- 
tes the properties of a neutral salt. S- No acid cm 
separate this colouring matter from iron after it iaenct 
united wtih it. 9. When tron dissolved in an acid \\ 
mixed with an alkali saturated with the colouring mil- 
lei', a double A' composition takes place ; the acid uoil» 
with the alkali, and the colourittf; matter with the iroo, 
and forms piussian blue. 10. Tlie reason thai, in the 
common method of preparing prunian blue, a quaatily 
of yellow oxide is precipitated, is, that there it nM ■ 
sufficient quantity of colouring matter (for the alkali is 
never saturated with it) to aaluraie all the iron displaced 
by the alkali ; a part of it therefore is mixed with pms- 
slan blue. Muriatic acid dissolves this oxide, carries 
it ofi*, and leaves the blue in a Mate of purity. — Such 
were the conclusions which Macqucr drew from liis 
(experiments; expericnentfi which not only discovered 
ihc composition of prussian blue, but threw a ray of 
light on the nature of aiTinilies, which has contributed 
much towards the advancement of thai important brmch 
of chemislrv. 



naliirc of ihe colouring malltr, however, wm Ch^. Ii'^ 
onknown. Macquer iiupposetl it lo be pljlogiston. 
According to liim, prussian blue is noiliing else than 
iron supersaturated with phlogisioii. This overdose 
protects the iron from acid", and prevents the magnet 
from acting on tl. Hest drives oflT this dose, and Itivci 
the Prussian blue in the slate of comiDon iron *. From 
this theory, which differed but linle from that of Geof- 
froy, the alkali saturated with the colouring mailer of 
Prussian blue received i\k name ol phlogisticaud alkali. 
Macquer having observed that it did not aci on alkaline 
lad earthy solutions, while it precipitated all the metals, 
proposed it as an excellent test for detecting the pre- 
sence of these last bodies. 

The subsequent e.tperimenis of chemists threw an 
xir of suspicion on Macquer's theory. Baiitnc ascer> 
isincd, thai when prussian blue is distilled, il always 
yields a portion of animal oilf ; a product not vcry 
lijccly to appear if the powder contained nothing; but 
plilogislon and iron. Deyeuic and ParmeQiier, Berg- 
man, Erileben, Delius, and Scopoli, submitted p/ui. 
sian blue lo disiillaiion, and obtained a quanliiy of am- 
monia. FonUna ascertained that pru^inn blue deto- 
nated with nitre. Laiiilriaiii obtained, by dislUIalion, a 
little acid liquid and oil, and a great quantity of azolic 
gas and carbureted hydrogen gas. These facts were 
klill more iMConsisteni, if possible, iviih Macqiier't the. 
ory. MoTveau advanced another in 1772; namely, thai 
ihe phlogislicated alkali, besides phlogistor, cunuined 
alto an actd which acted the principal part in the phe- 



• S.e MMijuet'i D'utUiurj,i 



\ Biumi't CliMulrj, a 



368 



COLORIFIC ACIDS. 



Book IT. nomena produced *. Sage afiinned that the coloiinn{ 

vnuon . jQ^tter in phlogisticated alkali was phosphoric add; 

but this opinion was refuted bj Lavoisier f • Bergmta 

also announced his suspicions that it was an a^d, botia 

unknown one %. 

Such was the knowledge of chemists respecting the 
nature of this colouring matter, when Scheele all at once 
removed the veil, and explained its properties and com. 
position. This he performed in two dissertations oq 
Prussian blue, published in the Stockholm TransactioDs 
for 1782 and 1783 ||. 

He observed that the prusstan alkali, after being ex- 
posed for some time to the air, lost the property of 
forming prussian blue ; the colouring matter must there* 
fore have left it. 
jDitcoveiy He put a small quantity of it into a large glau globe^ 
®f ^^''^^ corked it up, and kept it some time ; but no change 
was produced either in the air or the prussian alkali. 
Something must therefore displace the colouring mat- 
ter when the alkali is exposed to the open air, which is 
not present in a glass vessel. Was it carbonic acid gas? 
To ascertain this, he put a quantity of prussian alkali 
into a glass globe filled with that gas, and in 24 houn 
the alkali was incapable of producing prussian blue. It 
is therefore carbonic acid gas which displaces the co- 
louring matter. He repeated this experiment with this 
difference, that he hung in the g;lobe a bit of paper 
which had been previously dipped into a solution of 
sulphate of iron, and on which he had let fall two drops 



* Di^rett'iOHt AiaiUmijnes^ p, 24^. f Mem, Par, I 777, p. 77. 

; Notcj on Schcffcr, j l6<. j; Schcclc, ii. Z41. 



an alkaline lixivium in order to precipitate the iron. Chj p. m, 
rhis paper was taken out in two hours, a ad became co- 

ercd with a fine Wue on adding a litlle muriatic acid. 

^tbontc acid, ihen, ha; ihe property of separating ihe 

olonring matter from alkali without decomposing it. 
He found also that other acids produce the same ef- 

rct. Hence he concluded that the colouring matter 

night be obtained in a separate state. Accordingly he 
made a great many attempts to procure it in that state, 
and at last hit upon the following method, which suc- 
ce«ds perfectly. 

Mil together ten parts of prussian blue in powder, P"Pm> 
five parts of ihe red oiide of mercury, and thirty parts 

if irater, and boil the mixture for some minutes in a 
glass Tessel. The blue colour disappears, and the mix- 
ture becomes yellowish green. Pour it upon a filter ; 
ftad after all the liquid part has passed, pour ten parts 
tof hoi water through the filter to wash llie residuum 
completely. The oxide of mercury decomposes prus- 

iian blue, separates its colouring matter, and forms 
wilb it a salt soluble in water. The liquid therefore 
iwhicb has passed through the lilier contains the colour- 
combined with mercury. The other com- 
ponent parts of the Prussian blue beifig insoluble, do 
nol pass through the filter. Pour this mercurial liquid 
opoii 2i parts of clean iron filings, quite free from rust. 
Add at the same time one part of concentrated sulphu- 
ric acid, and shake ihe mixture. The iron filings are 
dtssolred, and the mercury formerly held in solution ii 
piecipiialed in the metallic itaie. The cause of tbis 
sudden change is obvious : The iron deoxidizes the 
nercury, and is at the same instant dissolved by the 
■alphuric acid, which has a stronger affijiity for it than 
JJ. Aa ' 



«i 



!<d a quantity of S»l ammoniac in small piece?, which Chip ID. 
pushed lo the bottom of the melted mixture, kept it 
^ in the fire for mo minutes till it hod ceastd lo give out 
J%«pour» of ammonia, and then threw it into a quantity 
^^rfWBter. The solution possessed all the properties of 
^Ae Prussian alkali. Thus Mr Scbeele succeeded iti 
^fcrming the colouring tnaiter. 

^_ This colouring matter was called ^ruMiVoci'rf by Mor- 
r Teau in the first Tolume of the cheiTiicalpart of the£«- 
^^tjfefoptdit Mtiliodiqut i an appellation which is now 
^"generally rccei^-ed, and which therefore it will be pro- 
P^rf lo employ in the remaining part of this Section. 
f^ These adtnirableexperimenis of Scheele wefe repeat* 
^«d and carried still farther by Berthollet in nST ; who 
applied to the explanation of the composition of thff 
colouring matter the light which had resulted from hisf 
previous experiments ori the component parts of ammo- 
niH. This illuSltious chemist, nol inferior lo Sciieele 
to ingenuity Ind address, ascertained, in the first place. 
thai the phlogisiicaied alkali is a triple salt, composed 
of prussic acid, the alkali, and oxide of iron; that ic 
mfty be obtained in ociah. dral crysisls ; and that when 
mixed with sulphuric acid, aitd extjosed to the light, ii 
lets fall a precipitate of prussian blue. His next object 
W&s lo ascertain the component parts of prassic acid. 
When oxymurisiie acid is poured into prussic ;icid, ob- 
tained by Scheele's process, it loses its oxyL^cn, ard ii 
converted into common muriatic actd. At (he same 
lime the prusste acid beciimes mofe odorotis and more 
Volatile, less ca;iab!e of combinitig with alkalies, and 
precipitates ir.m from iis solutions, nol bine, b\n grten- 
Thut prussic acid, by combining with oxygen, acquirer 
new properties, and is converted iiito si new (ubMianny 



L 



3*72 COLORIFIC ACIDS. 

Book IL which may be called oxy^prussic acid. If more oxj* 
muriatic acid gas be made to pass into prassic add, tni 
it be exposed to the light, the prussic acid sepanm 
from the water with which it was combined, and pi> 
cipitates to the bottom in the form of an aromatic oO; 
which heat converts into a vapour insoluble in water, 
and incapable of combining with iron. When the 
green precipitate, composed of oxj-pmssic acid ind 
iron, is mixed with a puce fixed alkali, the oxy-pmsac 
acid is decomposed, and converted into carbonate q{ 
ammonia. 

From these experiments, Berthollet concluded, thtt 
prussic acid does not contain ammonia ready formed ^ 
but that it is a triple compound of carbon, hydrogo^ 
and azote, in proportions which he was not aUe to ii- 
certain. This conclubion has been still farther veriSed 
by Mr Clouet, who found, that when aoimoniacd gu 
is made to pass through a red hot porcelain tube coiu 
taining charcoal, a quantity of prussic acid it fomied*. 
Thiik experiment does not succeed unless a pretty stroog 
heat be applied to the tube f. 

Fourcroy and several other chemists believe, that the 
prussic acid contains also a portion of oxygen ia its com* 
position, testing chit fly upon an experiment of Vauque* 
lin t* This is certainly possible, though it hu not 



* Ann, dc Cl'im. xi. 30. f /twr. A PEcole P^tyieekm. I. iii. 436. 

\ Vauquelin'h experimentt were ai foUowt : 

£xpi.ii. I. Put into a retort loo parti of the murUte of aousooit, 59 
parts nf iinie, and 2< parts of charcoal in fine powder ; sdipt to the re- 
tort i r.'ceiver concaiiiiiig a slight solution of the sulphate of iroa, ud 
immerse into it the bcMk of the retort ; then ippiy a brisk heat, and COB- 
cinue the action of the fire until notbiug more it diiengagcd. 



PKDSSIC. 31S 

been proved ; and the experiments of BertlioUct render C^p- P- 
M somewhat unlikely. 

Having thus traced the graduid progress of philoso- 
phers, in ascertaining the nature of the prussic acid, it 
tmiy remains to give an account of its properties, which 
were first examined by the indefatigable Scheele. 

. Prussic acid obtained by Scheele'a process is a co- Pfopmiei. 
Imtrless liquid like water. It has a strong odour, re- 
sembling that of the flowers of the peach, or of bitter 
jlmonds. Its taste is sweetish, acrid, and hot, and apt 
to excite couglt. It does not alter the colour of vege- 
ttble blues. It is exceedingly noxious when taken i'^- PoImiuhii. 
lernally, even exposure to the fumes of it proves fatal 
to unall animals. The poisonous qualities of the dis- 
tilled water of bitter almonds and leaves of laurel are 
•scribed at present to this acid, which is known to ex- 
tai in these waters in considerable quantity. 

It is very volaiile, and evidendy capable of assumiog G»=ous. 
the gaseous form ; though hitherto it has scarcely been 
examined in that stale. The following experiment of 



EiFEK. II. Put into t titon loo fiitiof [hcmuriitcof animenui, 50 
fan* of Klni-'vitreou] ovide uf lead, anil jj parti of charcoal; adapt! 
■cnivcT tontiining a whition of tulphstc of iron, and prtKetd u before 
Air wcil ihe liqaon contained inlhe refcivcrf, and npnac ihcm 10 the 
■ir fur Kvenl days in order thai the (Dinbuiii<aab(twc(.n the oaide of 
imci cod the prutcic acid aaj be pccfnE, and that ihc pnuuatc of iion 
may aliiorti ai much oiygcn ai it neceuary for iti panog to the naie of 
k1i>« pruuiaie, and [<tr ilt lcin|; ptOof agaiOiit acidi; then pour into ihne 
-Uquoneqaalqirantitiu oT HlphOTic tc id well diluud with water, aod 
]vii will have piUHJati bbe, the quaniiiici of which will be u one tn 
Ml { tbai iilo My, tlic pruuian blue cf the elpcrimcnt in whiih Vau- 
^udui Employed uiiile of lead, wat hi timet mure abundant than ihit 
of (he cipicimciit in whiihhc imp;M]'c>l ci.ty lin;t tg divrgage llie am. 




COLOKinC AUDI. 

Grindel, if aceurtte, &how> that it nuy be procund ii 
git. He put a quaiilily of prussian blue into a gli« 
fljsk, and filling lo it a bent lube, applied ihc tani of| 
lamp i at soon as tbc sm«ll of billcr almond* bccunt 
perceptible, the tube was plunged under metcnry, vd 
llic gai evolved received in 3 jar coniainiiig liquid pot. 
aih. The gas was absorbed by the potakti, and the i^ 
qui4i on being evaporated, deposited cryaiaU, v 
pLib\cs3cd all the propcriics ot [jrusiiaie ot pMaah'i 

From the recent experiments ol Rtchicc and Bucbolt, 
we Kain thai this acid is capable of resisting • mutk. 
more violent heat without dccomposiliOt thantojoE 
the vegetable adds. It is formed only wb«n the pot 
ash a<>d blood are exposed to a red heal. Whcu uniiBd 
to potash, a cousidciable heat may be applied to tl 
coDibination without occasioning dccompoMlion ; bat 
when Ihe sail is dissolved in water prussic acid ii im* 
mediately disengaged, as is evident by tlic odour 
bilier almonds evolved ; while at the same time 
tion of ammoniu and ol carbonic acid is turnied. Tdni 
we see that waier destroys the lombinaiion of this 
and alkaliii. Biicho'Z supposes thai the c&cci is pro* 
tluced by the mutual action of the acid and water wbtcEi 
decompose each other +■ These facts cxplata Ihe rea> 
son of the laciliiy wilh which the alkaline prussiaifl 
are decptnpoied by irerc exposure 10 the air, and by.aU 
the acids, and slmw us that ihej can scarcely be applied 
(0 any useful purpose in chemistry, even if their difB- 
culi foi maiion did not present an un surmountable bar Id 
fheir introduction. 



» GdilcnV y««-. i. 4cfi 



«» 



Eresence of a metallicoxide serves to fix ihc con- y^^F-^'- 
ul pruvsic acid, and to prevent them from being 
)n by water or any oiiier body. Hence those 
lu loio which a oicialiic oside enrers are much mare 
perinanent in tlieir nature, and of course may be used 
tu chemical purposes. 

Pmsiic acid ihcn may be prefKired as a reagent in 
-iMtr states : 1. In a stare of purity, eilher gaseous or 
dissolved in water. 2. United lo alkalies. 3. United 
to alkalies and mcialiic oxides at once in the Mate of & 
Dcmral sail. 4. United to [oecallic oxides alone. 

1/', In Ihe iiatc of prussic acid its action on metallic Auionoo 
solutions is bui feeble. Of all the meialUc solutions 
tried by Scheele, pure prussic acid occasioned only a 
precipitate in three : namely, 

1. Nilrate of silver precipitated while. 

2. Nitrate of mercury black. 

3. Carbonate of iron green becomingblue. 

It has no action on the oxides of 

I. Platinum, 4- Lead, 7. Manganeae^ 
a. Iron, 5. Bismuth, 6. Arsenic, 
3. Tin, 6. Antimony, 0. Molybdenum. 
10. Gold precipitated by the alkaline carbonates in 

rendered white by this acid. 

II. It disengages carbonic actd from the oxide of 
ailver, precipitated by the same alkalies ; but the oxide 
xemsios while. 

12. It dissolves red oxide of mercury, and forms with 
it a sail which toay be obtained in crystals. 

1 3. Ox'de of copper precipitated by carbonate of pot- 
ash effervesces in it, and acquires a slight orange-yel- 
low colour. 

J 4. Oxide of iron precipiutcd from the sulphate of 



m 



COLOUIIC AClDt. 

iron \if carbonate of potash, eflcrveiocs ia it, and bt. 
cgmca blue. 

15. Oxide of cobalt precipitated by the sune allcdi, 
gives in it some inarki of cffcivckccucc, and becoao 
yellowish brown •. 

2d, From the experimcnis of Scheclc, Richier, mi 
fiucholz, we iearn, ihsi the alkaline pruxsiatn la villi 
suiKcient force upon tnelsillic Rolutioni, und prodoei 
morc'bcaulitul prcctpiiales than llir triple prt»aiitH( 
bui, for tile reasons already assigned, they canoot be au 
troduced into use with udvantage. 

3ii, As the triple prussiaics arc usually prepared bf 
digesting alkuline bodies on prutsian blue, the aside tt 
iron IS the metallic body which enters into combi 
with the acid und bust, and con»titutca the camp0UD<j| 
triple salt. Poiaiih has, with one consent, been adopid 
by chemists ai most convcnicni ; but other alkalis 
dies w-ould doubtless answer equally well. Ferrvgu 

. aoui prvtiiaU of fiotasb, then, is the substance usnilly 
employed as a reagent. It is a yellow-coloured talt 
which cryslslliies in flat cubes. ItJs used to detect 
the presence of metallic bodies by the coloor of the 
precipitate formed, and in nn e<'pccial manner to detect^ 
iron, which it docs by the blue colour that the selutttB 
assunies ■., and to free solutions from iron, wbidi it d 
by precipitating the iron in the form of pnissian bloe. ' 

,f Mh, Tlie only soluble combination of pmssicacidiirf 
a metallic oxide is prussiaic of meretury : the mediod 
of ohlaining which is described above. It is a wbiM 
salt of a disagreeable metallic taste, crystallize* m, 



OALtlC. "^ 'ST7 

O^edleSy and forms a colourless solution in water. This Clup. in. 
tall is employed with great advantage in several cases. 
Bj means of it, for example, Dr WollastoD has pointed 
oat a method of separating palladium with facility from 
crude platina. Dissolve crude piatina in nitro-murp. 
«tic acid ; throw down the platinum with sal ammo- 
aiacy neutralize the remaining solution with an alkali, 
and then drop in prussiace of mercury ; a yellow pre- 
cipitate gradually forms, which, when heated to redness, 
leaves pure palladium. 

The only earthy bodies precipitated by the prussiattfs 
are zirconia and yttria. This property distinguishes 
these two earths from all the rest, and points out an 
imalogy between them and the metallic oxides. 



SECT. III. 



OF GALLIC ACID. 



X HERE is an excrescence, known by the name of /nsr/- Hiitory 
gaily which grows on some species of oaks. This sub- 
stance contains a peculiar acid, called from that circum- 
stanco|f a/& acid ; the properties of which were first ex« 
amined with attention by the commissioners of the A- 
cademy of Dijon, and the result of their experiments 
was published in 1777, in the third volume of their 
Elements of Chemistry *. In these experiments, how- 
ever, they employed the infusion of galls, in which the 



^ Vol. III. p. 4QZ* 



Mcli iteombined with ttnnin. It wa> reteive^ i« 
&lieclc to obiRtn it nearly in a state of patUy, 

I. lie obKcrvrd, in an infuMon of ({allt made wA 
cpM watei, a xetiiinFnt, which provMl on rxamnHtrat 
to Itave B crystallitte form and an acid tatte. B)rlcitn{ 
an infuiion of galU rcmaiti a long iini« cxpov«d loib' 
air, and rcmcn'mg row and then the mouldv ika 
which formed on ilk luKace, • large qu^niiiy of diii 
tediinent was obtained i which being edulcorated nr.h 
cold water, redtMolvcd in hot water, filiraied and »»■ 
poralcd vrry atowlj, yielded an acid ull in cry •»!» M 
fine as sand *. 

Dey^iix has proposed a oiuch apeedicr method if 
obtaining gallic acid f ; but it does not succeed with- 
out a good deal of pcccaurion. It con&ists in eapoiiag 
pounded nut-galh in a large glasi retort lo a heal ta^ 
tinusly and slowly raited. A number of bnlliaft whiia 
erystaUioc plaits arc sublimed, which possess all the 
properties of gallic acid. Care must be taken net B 
ap|;ly too great a heat, and le Mop the process bctott 
any til begins to come over, otherwise the crystals iriS 
be irdtasolved, and ihe whole labour lost. 

Mr Davy has lately pointed out another mrthad 
which yields gallic acid in a state of considerable pa- 
rity. Boil fur some lime a n:ixiure of catbnnate of bi> 
rytes and inlusion of nut-galls. A bluish frreen liquid 
is cbtatncd, which consisu of a aoluiion of gallic adi 



• SluUtlm Ttm-,. I jii—Tht crriuli obluiinl by thii nwtM iK 
wiyt coi.tain ■ purtiap of [innin, anc] arc oi ■ brown culour. 

+ Thi. Bitthod w» in fatl JiK-wrwl bj Scluele i hat Driem » 
pciud i[. and pointed uut ihc prapci |it<;cautiant.— -See Ci(U'« Jmjl, 
i 19. £ng. I'rmiL 




OilLItC. SIV 

nod baryles. Filler and saturate with diluted sulphu- Cli»i>.IIL 
tIc acid. Sulphate of barjtes is de]>osiied in the ttate 
of sn insoluble powder, and a colourless solution of gaU 
lie acid remains behind *. 

Many other processes besides these have been propo- 
sed by different chemists, but as they are all liable to 
considerable objections, it is not necessary to cnume- 
tale tlicm. The following method proposed by Rich- 
ter, though c^tpensive and tedious^ is one of the best : 

'* Intuse iti cold water one pound and a half of gait Meiholtf 
nnti, previously reduced to fine powder, taking care fre. '"" 

quenily to agitate the mixture. Pass the liquid through 
a cloth i add water to the pulp which refuses to go 
through, and again put it through the cloth, using a 
press to separate the water. Join the liquors, and with 
a gentle heat evaporate ibem, and a matter of a dark 
brown colour, and very britik, will be obtained. 

" Pure alcohol poured on this matter, reduced to a 
fine powder, acquires a pale straw colour. The drpositc 
infused again in alcohol communicates but little colour 
to it. The brown residuiina now left is composed al- 
most wholly of pure tannin. Mix the two alcoholic ex- 
tracts, which di&til in a small retort to one eighth. 
What remains will be almost a solid mass. Pour wa- 
ter on it, and expose it id a gentle heat, and you will 
obtain a clear and almost colourless solution. 

" Evaporate this solution, and you will obtain from 
it very small, white, prismatic crystals. The liquor 
furnishes more, but they are commonly a little colour, 
ed. It is lufBcient to levigate them with water to ob 



«S0 COLORIFIC ACIDS. 

Book II. tain them verj white. By this process half tnoooce 

Diviitiop II. ^ , . , - 9 ^ tt * 

\m y I of crystals is procured from one poand of galls ; thex 
crystals are extremely light, and consequently occupy t 
considerable space *.'• 

Method of The method of Scheele is by far the cheapest ; but 
it never yields a pufe acid. Mr Proust has propowj 
ifae following method of remedying this defect: Fotbi 
atrong infusion of galls, set it aside tiU impure crystili 
of gallic acid are de]^osited. Dissolve these crystabk 
water, and drop muriate of tin cautiously into the so- 
lution. Flocculi are deposited, and the solution becdtaei 
clear. Filter and evaporate. Pure crystals of gallic add 
are deposited, which require only to be dried upoo 
blotting paper f • I have tried this method of Proiut, 
but it did not succeed. BerthoUet has proposed ast 
substitute to heat this solution of gallic acid with reoeot- 
ly precipiuttd oxide of tin. But this method likewise 
failed in the hands of Bouillon La Grange, who hu 
lately published Sr dissertation on gallic acid, and en* 
deavoured to prove that it is merely acetic acid oom- 
.bined with tannin and extractive. But his proofisn 
not sufficiently conclusive. He has shown, however, 
that nutgalls contain acetic acid, and that the diffeient 
gallates, when decomposed by sulphuric acid, emit the 
odour of acetic acid }:. 

rt'T rtic^ 2. Gallic acid, when pure, is in the form of transpa* 
rent plates or octahedrons. Its taste is acid, and some- 
what astringent ; and when heated it has a peculiar and 
rather unpleasant aromatic odour. 



• P'^rf. Afjff. ,5xii;. -4. ^ j^^f.^ jg Poyt, Ixi. 1 17. 

J A'in, de Cbim, Iz. 1 5 6. 



r 



3. It is soluble in 14: parts of boiling water, and in t 
2 pans of cold water. When tbis solution is healed, 5: 

he acid undergoes a very speedy decompbidiian. Al- 
totiol dissolves one-fourth of Ha weight of this acid at 

le icropcTature of the atmospheie. When boiling hoi, 
dissolves a quantity equal to its own weight. It is 

iluble also in ether. 

4. When exposed lo the action of heat, it is sublimed, A 
but its properties are somewhat altered, as Bouillon La 
Grange has shown. In like manner the acid sublimed 
by Veyeux's process differs in iis properties from the 
crysialltzed acid of Scheele and Richter. Deycux an- 
noanced, that when ihe gallic acid is distilled it yields 
oxygen gas. When Berihollet repealed the experiment 
lie obtuned only carbonic actd. Bouillon La Grange 
has shown, tliat besides the carbonic acid, there comes 
over likewise a portion of heavy inflammable air, and 
that water is formed. By repealed distillations the 
whole acid may be decomposed and converted iDtotbfse 
products. Hence it is obvious that gallic acid, like 
most of the other combustible acids in composed ot 
oxygen, hydrogen, and carbon. TIjc proportion of car- 
boo, if we judge from the quantity of caibonicacid c- 
volvcd, must be very considerable. 

5. Gallic acid in crystals is not altered by exposure > 
lo the air. Neither oxygen gas, the simple combusti- 
bles, nor azote, seem to have any particular action ou 
it. Its action on the metals has not been examined. 
Wheti the solution of this acid in water is expoted to 
the air, it gradually acquires a brown colour, and the 
xcid is destroyed ; the surface of the liquid becoming 
covered with mouldiness. 

6. It combtucs with alkaline bodies^ separating th« 



f 



carbonic ictd if thty were in the slate of eafbouiei: 
The compounds formed have received ihc oame aigal. 
latfi ; but hiihcrlQ have scarcely been examined. 

1- In Blkaline solutions it occasiont no deposite, but 
when dropi into barytes water, itrontian water, or Iidm 
water, it gives them a bluish red colour, and occauoDi 
a flaky precipitate, composed of the acid combibed with 
the earth* *. 

Gallic acid Occasions a. pteCipitale «*hen poured into 
lolulifliis of glucina, yitrift, and tirconia in acid*. Tiiil 
property diaiinguishea ibete three bodies from all W 
Other earths, none of which are precipitated front tlieif 
solutions in Heidi hy gallic acid f . 

6. Upon the metallic solutions it act* with coasiden. 
ble energy, changing the colour, and producing pred pi- 
tates in many of them. Hence it is freijuenilj used ai 
a reagent to detect the presence of meiallic bodies; 
but the difliculty of freeing it sufficiently froiD tannin 
renders it scarcely safe to trust the expcn tncnts htlheno 
made oi> that point. Richter has shown, that it is not 
capable of taking iron from sulphuric acid, us has been 
hitherto supposed, unless it be asiisted by the a 
of some other body which has an aflinity for atilphnric 
acid. He has endeavoured to show, too, contrary H 
ihe experiments of Pioust, that it strikes a black with 
ell the oxides of iron. Hcnhoilcl has more lately em- 
ployed his ingenuity to establish the wme doctriDct, 



It untklic1|r iIiK thcK piKipil 
tile imniti, ind Ihii ibcj k 



tn *rc onaiiaiicil bf lb« fx- 

utJ ■liwppeu' iftbcwid itcft 



f If we eitepi iheir loluliuns 
Mled ttODi icidfliy iiifuiiun afn 



iibnnic K\,i. AlBDtinaii ftal^ 



rt Inrs by no means silenced Proust, who has publish* Chtp » nt^ 
experinnents apparently decisive. 
"When it precipitates metallic oxidfS, gallic acid ap- 
smrsto act by bringing them nearer to the state of me* 
Isy and some of them, as gold, are completely leduoedv 



SECT. IV. 



OF T A N N I K, 



HuTGALLS contain several other ingredients besides Hiitary. 
[^lic acid ; but one of the most remarkable and iro- 
)ortant is the substance called tannin, which will occupy 
mr attention in this Section. 

The first attempt at a regular examination of the prp- 
lerties of nutgalls was made by Dr Lewis, during a 
tx of experiments undertaken to ascertain the best mode 
f making ink *. He detected in them a substance 
rhich precipitates i/aci f with the oxides of iron, and 
jagulates uith isinglass :t t but chemistry in his time 
ad not made sufficient progress to enable him either 
> separate or examine this substance. Deyeux was 
erhaps the first chemist who ascertained the peculiar 
ature of tannin. He pointed it out in his analysis of 
lUtgalls ^s a peculiar resinous substance, but without 
assigning it any name §. Seguin soon after engaged 
n a set of experiments on the art of tanning leather |[ ; 



* Phil- t9phtcal Cbmmeree of the Arts, p. 377. 

f Ibtd. p. 346. I Ibid. p. 387. 

^ Ann. tt CJfim. XviL Sj. || Ibid. ZX. 3S. 



384' COLORIFIC AOIDS. 

Book u. during which he discovered that tamnm his the propeitr 
of precipitating glue from its solotions in water, andrf 
combining with the skins of animals* This led hio n 
suppose it the essential constiment of the liquids c» 
ployed for the purpose of tanning leather. Hence the 
names tannin and tanning principle given it bj tk 
French chemists ; but it is to Mr Pnmst that we are is- 
debted for the first investigation of the nature and pro- 
perties of tannin, and of the methods of obtaining it in a 
separate state *. Much curious and important io&r- 
mation has likewise been obtained by the experimcon 
of Mr Davy on the constituent parts of astringent vege- 
tablesy and on their operation in tanningf • Fiedlert, 
Kichter §, and Merat Guillot ||y have also published io- 
lerestiug experiments on this difficult subjoct. 

An elaborate dissertation on tannin was published bj 
Trommsdorf in the summer of 1804 ^^ in which he 
analysed the opinions of Proust, and examined the pro* 
perties of tannin with his usual industry. Many of his 
conclusions had been anticipated by Davy, whose h* 
boursy however, they serve to corroborate and confirm; 
but the recent labours of Mr Hatchett have formed a 
new era in the history of tannin. This sagacious phi. 
losopher, during a set of experiments on resins and bi- 
tumens, discovered a method of forming tannin artifi- 
cially from almost every animal and vegetable bodj, 
and thus furnished chemists with the means of proco- 
ring it with facility in a state of purity. His disserta- 



* Ann. de CLim. XXV. 125. — xtxv. 31, — and xlii. S9. 
f Piil. Trans. 18:.;, p. 233. and /wr. eftbt Foyal Instit. vo!. ii. 
I yui/r. de ChiiK, i. 86. § Ibiil. iii. 3C7. and 334. 

»; Ann. de CLim. xli. 32J. \ Gchlcn'i J9ur, iii. xil. 



nn an xnlticUl taiuiing subsiance were read to the 
Bytal Socicij in the summer of 18(>5. 
fXhcie diiCDX'cries will make it proper for us lo di- 
^ thii'suiijecc into tno parU. We arc aow ia pos- 
onof.two kinds af tanning one kind formed iii 
LS by tho pioccsica tif vvgetatign ; another formed 
ctaltj by itie mcthada poinied out by Mr Hatcbetl: 
of thcbC appears capable of .-assuming diiTofeot mo- 
ificatioti9,«i[herfrom «lig>>i allcraiiont in (be constiiu- 
|tl^ or from tbe combmauon of small portions of fo- 
il bDdici4 

i- 

I. Natural Tannin. 

1. Tann'In existsiuagrcatnumbrr of veeelable sub- 
ancesi but it nay be procured mou readily and in the 
rctttest purity from nutgal/s and catechu. 
NuTGaLLs are excrescences formed on tbe leaves of 1 
le oak by ibe puncture of an insect which deposits its | 
|gs on them. The best are known by the name of 
y*ffa gaiit, imported ifl large quantities into this 
BUQiry for the use of the dyer;, calico-printers, &c. 
^»Cy >rc hard like wood, round, often nodulated on the 
Bfface, of a bUiiili'coloUT, and »n excessively distagrce- 
Mile taste. They ate in a great measure soluble in wa- 
fer ; what remains behind is lasicless, and possesses the 
ipcrtiea of the fibre of wood. A very great propor- 
af water m necessary lo carry off every thing so- 
. Deyeus found, that a French pound of f utgalls 
red SB French pini.i of waitr, iijipr- i i-i CO »MTir- 
it portions one after tlie t'll'i, and allowed lo maee- 
PW. //. B b 



coLoktric Actoi. 

rate each s considerable time'. Tlii>, redaoedto«i 
sundard, gives us about ISO English pints to a p 
tray of nutf;alls. But Trommulorf exbaosicd thew 
ble part of nutgalU, by meaui of 40 times theit « 
of water, applied in three succetsivc portions, eactitail 
tiituing tno days on the galU, at the temperature of 6a*fil 
From the analyses of Dcycux and IHrjr, it faUoa^f 
that the soluble pact of nutgalls consists chiefly of fat* 
ingredients ; namely, ta&nin, extractive, mucih^^l 
gallic acid, and vallate of lime. Mr Davy found llnti 
500 grains of Aleppo galls formed with water ax 
lion, which yielded by slow evaporation 185 gniairfl 
nnticr. This mntier lie found computed of 
I'M tannin 

31 gallic acid and extract 

IS mucilage and extract 

1 2 lime aud saline matter 



185$ 

So thatthe tannin const! lutei rather norc than Iwo-lbirA 
of the whole. 

2. No fewer than live methods have been propoitJ 
to separate tan from the infusion of nutgalls, and pn)> 
cure it in a state of ptinty ; but none of ihcm ■ 
the purpose completely, 

Firif. When a solution of muriate of tin ii drappil 
'' into the infusion of nutgalls, a copious ycUow pfcdffc 

: immediately falls; whicli) when separated byfik 



■ Jtna. (/i dim. XTJi. I a, f Gehlen'i Jtur. iit. 1 1 j. 

1 Eiiriciin and omcilage itt ic|;Fiible (ubiuace*, wtiicb «ill 
IfnieJ sT m 1 lubiojiicnl pur of thii Wot£. 
i Piii.Tnm.itOi, 1st- 



tion and dried, assumes ihe appearance of a bufF-co- 
ired light powder. According lo Mr Proust, who 
Br^t examined this powder, it is a compound of oxide 
Df tin and tannin. If it be mixed with water, and a 
barrent of sulphureted hydrogen gas passed through it, 
ndphuret of tin is formed, which remains insoluble i 
the tannin, as it is separated from the oxide, dis- 
bolvet in the water. This water, v/hen freed from thc- 
■nlphurel by filtration, and evaporated to dryness, 
leaves a brown coloured substance^ which Proust con- 
sidered BI tirst as pure tannin *. But as the infusion of 
Inotgalls contains a portion of extract, which is likewise 
'precipitated bj muriate of tin, it is obvious, that b; this 
'process we do not obtain pure tannin, but a combina- 
tion of tannin and extract. Neither is the whole of the 
tannin precipitated ; a portion of ic combined with the 
lozide remaining in solution, unless thrown down bj an 
Mkalif. Mr Davy has rendered it probable that this 
■precipitate contains also muriatic acid J. From these 
{facts it is obvious that pure tannin is not obiained by 
til is process. 

I Steond, When the infusion of nuigalls,^ somewhat 
(concentrated by evaporation, is mixed with a saturated 
kolution of carbonate of potaih, a yellowi h white mal- 
tter precipitates Bbundanily in the form of flakes. When 
llhis precipitate is dried, it assumes the form of a whitish 
^wder, whicli vras first examined by Deyeux, (O 
lirbomwe are indebied for the process J. Proust consi- 
iden this precipitate as pure tannin; and accordingly 
\ 




• Aim.il CLUt. uv. 1)6. 
IfW. Tr™. «aoj,p. i49. 



f PmUH, An: ^i Cl<m. ilii. tf. 




a heal above 212°, lie obiained a yellowish coloured 
iquid, which gave a black, colour lo oxj^uljiliaii: of 
'S, though it formed no piecipiiaie with gelaiine ; it 
llcfcfore coiiiained gallic acid •. TrommsdorCs cx- 
ncnis show us likewise that this method does not 
Iield pure lajtninf. 
Faurtb. inime-water be mixi-d with SQ infusion of 
itgalls, a cDpious precipitate fall?. When this prcci- 
laie is treated with diluti.d nitric or muriatic aud, sn 
Icrvcsceiice lakes place, |i>c liquid becomes deep co- 
loured i and when filtrated leaves behind it a substance 
if a brilliant black culour, which AIcrat-Guitlot, to 
rhom we are indebted for lliis process, considers as 
mre lannint- Bui Mr Davy has shown thai il mu»tal«a 
Bontain (he extractive matier, which is thrown down in 
bombinaiion with lime as well as the tanning. The 
effervescence indicates sufficiently llie presence of cai- 
lic acid ; a proof that the precipitate is even still 
re complicated. This method, then, is scarcely pre- 
lirable lo the former. 
Fifth. The process praclited by Trommsdorf, tIiou);h 
>t uiMiiccptionahle, appears to yield tannin in a state 
bf greater purity than any other hitherto thought of. It 
Ik as follows: Three pans of nuigalls were reduced to 
powder, and digested with 40 pans of water for three 
days, at the temperaiure of fitj", ihe mixture biding fre- 
quently stirred. The whole was now passed through 
I linm strainer, the liquid set apart, and the powdered 
lutgallt remaining on the strainer were treated as be- 
Ewre with 40 parts of water. This digestion with fresh 



* fM. 'en. liaj MC. 
f Jmm. il dim. ill 313. 



( Gchkn't Jiar. m. 117. 
\FLU.^nm.\%Oi.\f,^. 




COLOKtriC KfilDt. 

water was continued lill four different 
hid been drawn nff tlio nuigills. Tbc lau of theie «it 
colourless, atid pruduccd ao change upon ilie wluticintl 
irnn. These infusions were mixed together, and cvapotu 
led ;:«iitly down to one fourth in a porcelaia basin. Th| 
liquid being now muddy wss passed ihrouf;h a iliii]) 
Ji'cii cloib, hy means of which a quantity of n 
via<i -.rparaied. The whole was then evaporated loth 
coiisisiencr of a jelly, and placed upuii a flat porcc 
dish near a stove till it became quite dry. The hn 
coloured substance thus obtained was digenied i 
thriire its weight of purt alcohol * i and this digcuim 
was repealed in all three times, till the Ukt portion ^ 
alcohol was found to contain no trace of gaUic add. ]| 
order to make sure of removing the gallic acid, tlie ib 
residue was digested twice succtGsivcly with alcolHl 
coniainiug \ra ptr tent, of water. It was now con^ 
dered as tannin in a considerable degree pure, bats 
contaminntcd with some cxiraclivc and mudlaginoai 
matter. To get rid of these, the whole was dinolvtt 
in distilled water, and repeatedly evaporated id dryui^ 
in hopes of rendering the extractive insoluble ; but OO' 
thmj; was scparaied by this process. When the loltuiok 
was left for some time in a warm place, a mould roU 
Icclc'd on the surface, which was removed, and ascribei 
Id a portion of mucilage which had been present. Tht 
soluiiun being now tillered, and evaporated to dryacH^ 
Irfi a residue conMsting of tannin in a state of considet*> 
Lie purity, but still coutaminaicd witti a quantity o 
sulphate ol lime. To get rid ofthii tali. Mi TrMnai* 



■ • Alcuholordicipeuficgrairicf o-;96i>i[p«K»t (ownlcreda/wii 
n bci Uvn »at(t. 



brf employed the following method ; The tannin was t*'P ' 

tnlved in water, and carbonate of potash dropt in as 
g u any precipitate fell. The liquid was separated 
rom this precipitate by filtration, and mixed with ace- 
kte of lead. A powder fell, consisting of the oxide 
B lead combined with tannin. This powder was wash- 

£md dried ; and being mixed with water, a current of 
pliureted hydrogen was passed through. By this 
Ibeani the lead was separated and remained in combi- 
luioQ with sulphur, while the tanam dissolved ii> the 
Inter. The liquid being now filtered, boiled, and eva- 
porated [o dryness, left a residue, which may be consi- 
lered as tannin in a state of as great purity as it can be 
Reared from nutgalls ". 

' 3. Catechu, or tirruyo^ojnVfl as it is also called, is Fn>m« 
k substance obtained by decoction and evaporation from ' '^ 
i species of mimosa which abounds in India. It has 
ft reddish brown colour, an astringent tasie, leaving an 
hnpression of sweetness ; it is not altered by exposare 
k> (he air. There are two varieties of it; one from Bom- 
lay, which has the lightest colour, and a specific gravis 
Ijrof l"30; and one from Bengal, which is of the co- 
lour of chocolate ; its specific gravity is I'SSf. This 
labsiance was examined by Davy, and found to consist 
chiefly of tannin combined wiih a peculiar species of 
pxlraciive. If the darkest pans of liic calechu be se- 
lected, and infused in cold distilled waier for a short 
Lime, the infusion, when evaporated to dryness, consists 
bfianain combined wilha very minute quantity of exiract. 
It may therefore be employed to asceriain the properties 
of tannin. 



i D"r, n 



^02 COLORIFXC AGIOS* 

^onk i(. 4^ Tannin procured from natgalls hj TrommsdorTi 
I ^\- method^ is a substance of a brown colour, brittle^ an4 
in.pcrtica. breaking with a resinous fracture. Its taste is bitter 
and very astringent| like that of nutgalls. 

It dibsolves readily in water,; both hot find cold, sod 
fornris a solution of a brown colour, which, frofnTromai. 
dort*s experiments, does not seem liable to becooe 
mouldy, nor to under|;o a spontaneous decompoutioa 
wijvn c^cpostd to the air in a moderate heat. 
ln?»oluWc ID i\jy., ..icohol does not dissolve tannin ; but it isrea. 
diiy si^iiibic in alcohol diluted with water, even though 
the ^j.if.ion of waier be but small. Thus alcohol, of the 
spii jfu jM*i^".ty 0*818, di.NSolves it, though it co«)tainS| 
acc.UwjiiM'- lo Lowjiy/s table, only* Y'^-th of water. Thtie 
ia)|joi :ai;i tacts .>evni first lo have been observed byRicb- 
tci, aiivi to have lurnidhed him with the method fort 
nxTly dcdCribMi, ot piocuring gallic acid in a state of 
purity. 

t\. From the experiments of Proust, Davy, and Dej« 
eUA, vvc learn that it is capable of combining with ozj- 
gen , but at the same time it is either decomposed alto- 
gcthcr, or its nature completely altered. Thus nitric 
acid converts it into a yellowish brown matter soluble 
in aicoho), and similai* in its properties to an extract*. 
()\y:nuriaiic acid produces similar cficcts ; and Mr 
PrcHist has observed, that the peroxide of tin changes 
it nlso into an extract f, perhaps by communicating 
oxygen. 

6. The action of the simple ccmbustibles on taonia 
has not been examined. 



Arti'in of 



^ l>.ivy, i» ,;. ;,„«/. i: rj.. 241. f A/m. de CUtf.: xLi. 9;. 



TAMHIK. 393 

action of the metals upon tannin <locs not Chtp. lit. 
to be gieat i but almost all ihe metallic oxides Acnonuf 
an affinity for it, and arc capable of combiuiog "'''1''^*^ 
it i the compound is usuiilly nearly insoluble in 
I^lence the reason wliy the infusion ofnutgalls 
[tatcs metallic soluiions so readily. These com. 
have been hKlierto in a great measure overlook- 
ed by chemists. The following observations contain 
3 £acts at present known. 

When the peroxide of tin or zinc is boiled in the in- 
fuuon of galls, it acquires a dull yellow colour, and ab- 
ftracis all the constituents from lite infusion, leaving 
bebind only pure water. The oxides thus combined 
with tannin, Sac. are partly soluble in muriatic acid, 
and the solution iiidicales the presence of tannin and gal- 
lic acid •. When peroxide of tin is allowed to act upon 
the cold infusion, ii abairacis all its consiiliients in a 
few days i but MrProu^tf siErms, that in that case 
the gallic acid is mostly destroyed, and a portion of the 
lanoin brought to the state of extractive. 

When the metallic salts are mixed with the infusion 
of galls, the precipitate consists of the metallic oxide 
combined with the tannin, the extract, and the acid of 
ibe infusion ; and, according to Davy, it contains also 
a portion of the acid of the metallic sail 1. 

Tannin docs not seem to produce any change upon 
the solution of sulphate of iron : but when it is mixed 
with a solution of ihe oxysulphaie of iron, a deep blue 
coloured precipitate immediately appears, conusling of 



• Djtj, em. TrMi. 1803, m. 

I nil. Irati. 1803, 14S. 



t ^n.ACtw-xUl^i. 



COLOXtnC ACIDS. 

ihe tannin combined with tho oxide. Thii prccipiou, 
when dried, assumes s black coloor. Tt ii dcoompoid 
by acids. 

When too great & proportion of oxysulphatc of troo 
is poured into a solution of tannin, the sulphuric idd, 
set ai liberty by the combination of the iron and tnnlti, 
is sufficient to re-dissolve the precipitate as it apptin; 
but the precipitate may easily be nbtained by cauiiouil; 
saturating this excess of acid with potash. When [lis 
experiment is performed in this manner, all the nj- 
sulphate of iron which remains in the solution undecom- 
posed is converted into sulphate. Mr Proust suppoxi 
that this change is produced by the tannin abtoTbitig 
oxygen from the iron. 

&. One of the most important properties of lannin ii 
the insoluble compound which it forms wilh^Aif or^ 
laline, as this substance is termed by chemists. It is 
therefore employed to detect ihe presence of gelatine is 
animal fluids ; and, on the other hand, solutions of |c> 
laiine are employed to detect the presence of tannin ia 
vegeinbla iluidx, and to ascertain its quantity. Now 
-dhhough the compound of geUiine nnd tannin i* 
lubte in water, it is soluble both in the solution of tao. 
nin and ot gcbtine when suflicicnlly diluted. It is itc- 
cestary, therefore, that the solution of gelatine, uMd 
delect tannin, should he as concenirated «> is consiueat 
wiih its perfect fluidity ; for ghic, when gelatinous, 
not act upon tannin. It is necessary also that it should 
be employed quite fresh ; for when in a state of paiTc- 
fiiction, it loicji Its property of precipitaiiog tani 



• 1 6nd ihai nra ihc idilition of u Diuch alcfihul u >• ci 
the eeluiac remaining inicluiiiD, iou uot ytttem iX io* ytv^n* 



T Davy hitj ascertained, thai the best proportion for 
a solution of 120 grains of isinglass • in 20 oun- 
XI of naier. Care must be taken not to add an excess 
Bf ihe soluiioti to ihe liquid from which the tannin is 
be separated ; because ihe compound of tannin and 
latine is re-dissolved by the solution of gelatine. Ac- 
Bording to the analysis of Mr Davy, this compound, 
Kben dried in the temperature of 150*', is composed of 
54 gelatine 
46 tannin 

JOOt 

r i>. Potash and soda combine with tannin, and form 
|;Wilh it a compound less soluble in water than pure tan* 
^M, and which does not precipitate glue till the alkali 
Bs saturated with an acid X- Ammonia produces the 
name efieclt. The fixed alkalies occasion a precipitate 
Un concentrated solutions of tannin, but ammonia throws 
j^wn nothing J. 

I, When potash or soda is added lo the infusion of nui- 
galU, the liquid assumes a reddish-brown colour, and 
loKS the properly of precipitating gelatine (ill the alkali 
W saturated with an acid. When the alkalized infusion 
is evaporated to dryness, an olive coloured mass re. 
Siains, of a faint alkaline taste, which deliquesces in the 
Ammonia produces the same effect upon the infu- 
ion of galls i but when the mixture is exposed to the 



IT gtUiim 



Wh«t. 

I fPti/. rru/.t£oj.p.33j.uidijc- 

I, 1 TrcmmHlaif, Gchlcu, iii. 1^4. 




I7 pure, attai becD thowQ bjiA^i 



306 COLORiriO ACIdS. 

BorvV TT heat of boiling '^water, part of thr ammonia flies off, t 
q precipitate falls, consisting of most of the tannin sad 

gallic acidy while the exfract remains in solution ^. 
Of carthi, jo. When barytes or lime water is poured intoaio- 

lution of tannin, a precipitate falls, consisting of taasia 
combintd with the earth, and the solution becomcsnear- 
Ij colourless. The precipitate dissolves with difficult 
in water, and does not act upon the infusion of gluedtt 
the earth is saturated with an acid *. 

When newly precipitated magnesia is agitated with 
the iniubion of tannii , it unites with a portion of i^ 
and foniis a smokj brown powder insoluble in water, 
but soluble in acids* Alumina produces the same cf* 
feet, and forms a simiia' compound f. 

When bar\ tcs, strontian, or lime water, is poured ia- 
to the iniuM<tn of ^ails, an olive coloured prcdpitite 
falls, which consists not only of the tannin, but also of 
the extract, and roost of the gallic acid cumbioed with 
the earth. When magnesia is n^ixed or boiled with 
this infusion, it combines with all its constituents; the 
gallate remains mostly in solution, and gives the liquid 
a green colour ; while the tannin and the extract form 
with the magnesia an insiiluble compound, and give its 
dirty yellow colour. Alumina in small quantity pro. 
duces exactly the same tiiVct ; but when u%«:d io a great- 
er proportion, it separates all the constituents of the in- 
fusion :{:• 

When the earthy carbonates are boiled in the infusion 
of galls, they separate the tannin aiid the extract, while 



5 Divy, Phil. Ir'ns l8o;,n. 141. 

• Tronur.svl' rf, G'-hltn' J r. i.i. 14J. | Ibid. 

I Davji Fiil, Lrum. 1^03, p. 241. 



f_ cortlbine wlih the acid, and form with it a salt Chip - HI. 
I remains in the liquid, and gives it a green co- 



Most of lie acids have the property of combi- 
ttig with tannin, and of farming solulions more or less 
Acetic, phosphoric, oxatic, and malic acids, 
ccuian no precipitate when tlropl into a concentrated 
elmion of nutgalls. Arsenic acid produces a copious 
irecipitsie, soluble in boiling tvatcr, and prccipiiaiing 
loe after ihe acid has been netiiralized b)- an alkali, 
ifuriaitc acid likewise produces a precipitate most- 
f soluble in hot water. The same remark applies 
to sniphuric acid. But this acid alters and gradually 
Secooiprigcs tannin. Niiric acid produces no preeipi- 
Ite in the infusion of nulgalh. The mixture becomes 
loi, and assumes a red colour, tvhich gradually chan- 
Ifes to 9 yellow. By the aciion of ihis acid a bitter- 
JHsted substance is formed, which possesses the proper- 
malic acidf. 
- 12. When tanniii is distilled, il yields an acid liquor, 
'tiich blackens solutions of iron, because it contains a 
litde tannin unaltered: there cotnes over also some 
frtnpyreumaiic oil, and a voluminous coal remains be- 
hind, amounling^ to -^'^ of the tannin distilled t' 
^' IS. Soch are the properties of the tannin of nutgalls, 
ts far as they have been ascertained. ThediSiculty of 
procuring it in a state of purity renders some of them 



• Da»7,P4//. Trwi iSo 
t Tronuiui'.orf, Gihlcn'* . 



COtOBtnW ACIDt. 

_ ■mbiguoui, and hns induced chemitU to employ i) 
reagfcnt the entire solution of naigall*. 

This solution is employed in considerable qnublia 

by the (trcrs, jtnl it fotni', ilir principal iDgrcditmi 

•writing ini. It \i not known at what period tbii i^ 

portani liqtiid came into use ; but the ink of the b 

cienis wni composfd of very difTerettt iagrcdicDli, W 

I Ing analogoas to the ink used by the priolcn u p» 

\ tent. We are indebted to Dr Lewis for a valuable 

I 'of experiments on (he best mode of making ink. 

W' This liquid consists of ft solution of sulphate of im 

l"3n the infusion of nulgalh, and seemn to owe itsfahd 

pcolour chiefly to a combination of the lannin iritb lb 

t'oxidc of iron, or perhaps with the sulphate, and ptrt|f 

o to the combination of gallic acid and oxide of in 
C*Thc fullest black is produced when eqaal nvighlti 
V^grcen vitriol and galls are used ; but the ink rttjm 
'fades. To make it permanent, the galls ought loll 
thrice the weight of the vitriol. No other soliuiMd 
iron but the sulphate forms with nutgalls a full blui. 
When the mixlureof the infusion of nuignlls and grra 
vitriol is diluted with much water, the black matnt 
precipitates, and forms a sediment not again soJubk, 
The addition of logwood increases the blackncM of ilx 
ink. The following formula was ascertained by Or 
Lewis to yield the best ink. 

Logwood............! ounce 

Nutgalls in powder. . . . K 

Green vitriol 1 

Water 1 to 2 quarts 

Boil the logwood and nutgalls in the water, adding new 
liquid in proporttoD to the evaporation, then iinia 
through a cloth, and add the vitriol to the water, tdi. 




ing at the same lime from one to two ounces of gum Clup. llf. 
nbic. As soon a« these have dissolved, the ink isfic 
W use *. Some recommend the addition of a little 
n powder to prevent moutdiness. 
14. Mr Proust has announced it as his opinion, that 
:xist various species of lannin in the vegetable 
UBgdom, differing from each other like the oils, resins, 
|cc. He has even enumerated several of these varie- 
, and pointed out their characteristics f. 
It is by no means unlikely that this opinion is well Sp«iei»f 
jided, and the experiments of Mr Halchett serve to 
Dctnfirm it : But it is impossible to admit it as demon- 
rated till a process be discovered for obtaining tannin 
3n m state of purity ; for llie differences between the 
varieties pointed out by Proust may be owing to the 
of foreign substances which disguise its 
properties. At any rate, this subject will come under 
tmr consideration more properly in the Second Part of 
this Work, when we enumerate the different vegelablc 
mbstances that contain tannin. 

II. Artificial Tahnim. 

TflE important discovery, that a substance possessing Di«mttT7. 
similar properties to the tannin of nutgalls may be 
formed artificially by a very simple process, was made 
by Mr Haichetl in the course ot a sl t of experiments 
on the slow carbonisation of vegetable bodies, and de- 
tailed by him in two papers read to the Royal Society 
in 1B05. 



■SceLe«a'tP^i/.C«>.p.]77. f J*<. tfi CJin illi.94 



■ Proptrtie*. 



cflLoitfrre ACIDS. 

1. To form ihis arlifieiaiiannia, we liavc only toe 
gest diluEcd nitric acid on charcoal till the wlioli, 
nvAtly the wbole, is duiulved. Mr Hotchcit imiuI 
employed ICID grains uf charcoal, aad $00 gniu 

'nitric acid of the specific gravity l-40, diluted with tirj 
'lis weight ofwaicr. On tlealtpg this tniiiurciiiaaai 
9wirau a conudernblc cRVrv««ceiic« wa» produwd, i 
rnich niirous gas escaped. Afict (wo days djj 
lUore ntiric acid w» added, and ihu digotion wm « 
linucd till the tolutiou was complete. The *oluii 
thus obtained wat tf jusparcni, and of a dark brawm 
lour i which being evapotaicd lodryncM, Icavctabiatq 
wloured mass. Ttiis is the ariilicial tannin. To fiu 
if from the last poriioni of uiiric acid, Mi Hauhct 
^und the best method wmb |o dt»5oIvc it repeated!/ 
iTitier, and evaporate cautiously to dr^neu with km 
lie heat. 

By this method IDO grams of charcoal were conTtnt 
•d into 120 grains of artificial tannin: but of iht* 
Mr Hatcheit supposes three grains to be morsioic. 

2. Tannin thus prepared is a substance of a bn 
colour, has considerable lustre, and breaks with i 
trcous fracliire. lis taste is bitter and highly 
gent. It lint no smell. 

Ii dissolves readily in cold water, forming a 
jsrcni solution of a deep brown colour> 
^jtsolvca it*. 



• The akohol u>fd by Mr Hiichcit nw prohiMy y 
tion el pure alc.>h<:Mia> not Iwcn tricil. Were it uluble 8g 
form i marked <<i<iuictiiin Iwtween nicural uid trti 
tlie dTcct of lUohol pT the ipctiGc Krivity o-Sc«, ij 
mj eg«eMk>iL 1 1 fatmed > pale ycUbw nhitign. 



3- The solui 
pitaies glue. 



;ion of artificial tannin immedialely pre- Chip. III. 
or isinglass, from water. The precipi- PrecipiUiM 
or less brown according 10 the strength ^'''•' 
the solutions, and always insoluble both in hot and 
Id water. To ascertain the proportion in v.hich these 
Aits unite, Mr Haicheil disWved 50 grains of artifi* 
bonlD in 4 oi. of waitr, and ihcn precipitated by 
ie«n> of a solution of isingbss. Forty-six grains of 
Me tannin were prccipiinted in combination with eighty- 
h^ grains of isinglass. Hence ilie precipitate is com- 
■•ed ot' about 
r 36 tannin 

04 isinglass 

ICO 
tlie solution containing the four grains not precipitated 
'jr the isinj;1ass being evaporated to dryness, left a light 
■ciitlc substance of a pale broiVn colour, sAietling strong- 
^ of prepared oak bark, especially when dissolved in 
Vaicf. The solution tasted bitter, and from its proper- 
ics approached nearer to tbc vegetable matter called 
fjitratiive than tannin / a proof that even the ariiScial 
laanin prepared from charcoal is not quite free from fo- 
r^cign bodies. 

4. When sulphuric acid is added to a solution of «r- itiii, 
tificial tannin, a copious brown precipitate falls^soluble 
in bmling water, and capable of throwing down gela- 
tine. Muriatic acid produces precisely the sai 
Artificial tannin dissolves readily in nitric acid, but is 
cot altered in its properties, though that acid be repeat- 
edly distilled off it. In this respect it dtflcrs very ma> 
tcrUlly from oil the species of natural tannin hitherto 
cjuunioed, which wcie fbimd by Mr Hatchett to be en- 

r«/. II. ^ Co 



COLOKIVIC AClDi. 

tirtly decomposed by nitric acid, ibotigh with d 
degrees of f«ciliiv. 

5. Arrllicia) tannin onilei rcadi);' with ibe alki 
both lixedaiid rolaiile. When dissolved in a 
evsperated to drynesi, and again diMolved in wawr.fl 
new soWition does not precipitate gelatine nolen il 
previouity mixed with a small portion of ronriaiicK 
A proof that il still retains the amtnonia in CDmhi 
tion. When the fixed alkalies are added to a solid 
of artindal tannin, the colour is imincdialcly dtepa 
and after some liour^llic solution becomes inrbid. I 
botiale of potash produces the same effect, anij li 
some time .1 brown magma is deposited. 

6. The alkaline earths nniie with artificial tnuis, 1 
and form compounds litlle soluble in water. Hen« ii 
forms a precipiliie when mixed with nitnunof li 
barytes, &c. 

"7. It precipitates likewise most of the metallic oi 
from their solutions in acids. The colour of the pn| 
pilate is usually brown, inclining to chocolate. 

8. When artificial tannin is thrown upon a hotnj 
it emits an odour similar to that of burning feilho 
When exposed to a graduated heat in a retort, there p 
ses over, in the first place, a portion of water ; andfl 
is succeeded by a litile nitric acid, from which itis4l 
eult to free it completely. • A little yellow DqoorM 
makes its appearance ; and upon raising (he Cm, amsK 
niacal gas is disengaged with 'gteal rapidity, Thit n 
followed by ihcevoimion of carbonic acid ga*, tcgtthw 
with a small portion of gav which seems to poMest thf 
properties of azote. A bulky coal remains iuihert- 
tort, amounting in weight to fy42S of the original tk- 



Ui> Xhis coal being burned, left some brown asbes, 
posisting chiefly of lime. 

From this decomposition by the action of fire, it is 
brioiis, thm artiliciid tannin is composed of oxygen, 
itMe, hydrogen, and carbon. The last ingredient ob- 
iousty predominates ; though the proportions have not 
bitherto been ascertained. 

Soch arc the properties of the artificial tannin from 
llurcoal, as far as ihey have been hitherto ascertained 
if Mr Hatchett, to whom we are indebted for all the 
frcU xbove detailed. From the experiments of this in^ 
Mcfatigable i.hemisl, we learn that every kind of chgr- 
l^oal yields it equally, from whatever substance it has 
Jieen formed, whether vegetable, animal, or mineral, 

erovided it be in the slate of charcoal. But the action 
,f nitric acid on charcoal, though the readiest and easi- 
est process, and that which yields the greatest quantity, 
i not the only one by means of which artittcial tannin 
nay be formed. Mr Hatchett has pointed out two 
libers, by means of which certain vegetable substances 
may be converted into tannin. 

g. The first of these consists in digesting nitric acid 
turith certain substances that appear to contain an un- 
cotnmon portion of carbon in their composition i indi- 
go, for instance, and many of (he bodies called resins. 
Indigo dissolves readily in diluted nitric acid, and the 
ilution, when gtmly cvaporaied to dryness, leaves an 
' •range-coloured mass of an intensely bitter taste, solu± 
ble in water, and possessing the property of forming an 
I Insolnblc precipitate with gelatine. Htnce it resembles 
tannin j but it acts more feebly on the metallic salts 
[ than tannin from charcoal. A similar substance was 
procured from common rf ?in by digesting it for a long 



Secontl y, 
(■etyofa 



eOLOMRO ACISt. 

Bmii tl. time in diluted nitric acid. Most of the mine md 

PiTiifun II. . . . 

«— V resins gave a similar product ; but no tanaiii cnaldh 

procured from the gnm*. 

Third*!- IC The other pfoccM for procuring artificit] 

*' coHMsIs in dissolving reiins and camphor in siilphvic 

acid, digesting the solution till it betomes blick, vi 
then prccipitattitg by ihrouing it Inlo cold w>»r. 
black powder falls. If lliis povrder be digetledtm 
cntiol, a brown sitbsinnce is taken up, which ii solol 
boih in water and alcohol, forms an insoluble predj 
t tale with gcUiinc, but ac« only feebly on oxy-tnlpbi 
oF iron. Camphor by this process yields nearly half i 
weight of a brown resinous-like tnaiier, which potsn 
the properly of forming an insoluble precipitate vilfi 
gelatine i and when digested tvith a little nitric tci^ 
becomes precisely similar to tannin from charcoal. 

Thus there are three speoips of ■nilicial tannin. I. 
Tannin procured by the action of nitric acid on chir- 
coal. 2. Tannin, by digesting nitric add on indigo nl 
resins. 3. Tannin, by dissolving resins or eamphi 
sulphuric acid *. 

Such are the properties of the colorilic acids. Tiitj 

act with most energy on metallic suluiiuns, foniiiii| 

precipitates which vary in colour according to the mu 

Cheminl '*'• '' '^ ''''* propeny which renders them of 

^5**'''" importance in a chemical point of view. The coloaf 

cidi, of the precipitates which each of these bodies farmt with 

the different metallic bodies, as far as is knntvD RI pre> 

sent, may be seen from the following Table. 



* See Mr Haichctt't |ii[>en, P'l/. Tnuu. iSoj aoJ ited. Inm 
wbich &U tU t:cti tcnKcucganificol laaain hue bc^u iiLeik 



COWRIWC ACtDS- 



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4^* fdMPoimD couiomiLEt. 



CHAP* IV, 



OF COMPOUND CO?*"*' 



1 HE dompound combustibles are almost mil oonpfiel 
of carbon and hjdrogen, or of carbon, hydrogen, tnl 
ozyoeo. Thcj are a vetj numerous class of bodies, 
comprehending the greater number of antma) and vc« 
getable substances, and of t)ie product^ obtained fnm 
^um!)fr of these substances. But The present state of chemistrT 
fominirti. does not permit us to takp the term |n that coBDpre. 
^^ hensive ftense : The investigatlpii of yrge table and sni- 

mal bodies is too incomplete j their propcrtiea are too 
imperfectly known to allo^ us to introduce them into 
the first principles of the science; and the utiliijofthe 
greater number of them as chemical instruments is too 
inconsiderable to warrant any such introduction, ertn 
if their propenies were completely investigated. For 
these reasons, it will be proper to treat in this Chapter 
of those compound combuMibles only which are em- 
ployed in chemistry as instruments of investigation, re- 
serving the remainder for the Second Part of this Work, 
These may be reduced under five classes ; namelyi 

1. Alcohol 4. Fixed oils 

2. Ether 5. Bitumens 
r*. Volatile oils 

The properties of tlieie bodies form the subject of the 
frllowing Sections, 



or ALCOHOL. 



X HE liquid called alcohol, or ipirli ofviinc. Is obtained fii<«7, 
ty distilling -xiise, beer, and similar ferirented liquors. 
7hese liquori appear to have been known in the ear. 
licst age!. The Scctpiure informs u. that Noah plar.l. 
cd a vineyard and drank wine ; ar,d llie heathen wtU 
teft arc unnnimoui m ascribing the iiivcntion of (his U- 
c|uor to their earliest kings and heroc*. Beer, too, seems 
to have been discovered ai a very remote period. It 

WHS in common use in Egypt during ihe time of Hero- 
dotus*. Tacitus informs us that it wat the driuk of 
%ht Germans f. Wheticr the ancients had any method 
of procuring ardent spirits frcui these or any other li. 
qiiors docs not appear. The Greeks and Romans seem 
ta hav« been ignorant of ardent spirits altogether, at 
7eatt we can 4'!covcr no traces of any such liquor in 
their writings ; But among the northern nations cf Eu- 
rope, intoxicating liquors were in use frota the earliest 
Kges. Whether these liquors resembled the beer of ihe 
Germans we do not know. 

At what period these liquors were first subjected to 
distillation is unknown ; though it can scarcely have 
preceded the Itme of Ihe alchymists. The process is 
ciinple. Nothing more is absolutely necessary tbaa 



f Dr Atrrii. Gi-». A li 



^O COMPOUND COMBQSTIBLES* 

Book IT. to boil them in a still. The first portion of what comes 
> ^" over is ardent spiriis. It is cortmin^ mt least, that the 

method of procuring ardent spirits by distillation was 
known in the dark ages $ and it is more than probable 
that it was practised in the north of £urope much car. 
lier. They are mentioned expressly by Thaddanis, Vil- 
lanovanusy and LuUy *• 
^ It is by the distillation of fermented lienors that ar- 
dent spirits are obtained ; and they receive varioas namei 
according to the nature of the substance employed. 
Thus brandy is procured from wine, rmm from the fer- 
mented, juice of the sugarcane, wbisip and ^m from the 
fermented infusion of malt or grain. Now ardent tp^ 
rits, whatever be their name, consist almost entirely of 
^bree ingredients; namely, water, ^«r« jr^firiV or alco- 
hol, and a little oil or rejin, to which they owe their fla- 
vour and colour- 
Rectified 1. When these spirhous liquors are redistilled, the 
•ptriti. g^^^ portion that comes over is a fine light transpareat 
liquid, known in commerce by the name of rectified 

m 

Spirits, and commonly sold under the denomination of 
alcohol or spirit of wine. It is not, however, as stroig 
as possible, still containing a considerable portion of 
water. 
Pk'cpantion The method usually practised to get rid of this ws- 
ter is to mix the spirits with a quantity of very dry 
and warm salt of tartar f . This salt has a strong attrac- 
tion for water, and the greatest part of it is insoluble in 
alcohol. It accordingly combines with the water of 



* Bergman, iv. art. ii. 4. 

} laipiirc pct?-ih not fully saturated with carbonic acid 



ateoBOLT ' "■ ■ '*W 

"■the spirit; and llie solution thus formed sinks lo ihc Ch»p. IV. 
botiom of the vessel, and the alcohol, which is lighl«r, 
swims over ir, and may easily be decuiied o&'; or, 
what is perhaps belter, ihc solution o£ potash may be 
drawn off from below it by mean* of a stop-cock placed 
at the bollom of the vessel '. The alcohol, thus ob- 
tatued, contains a little pure pota&h dissolved, which 
TDay be separated by distilling it in a urater bxili with 
a very small heat. The spirit passes over, and Icavct 
the potash behind. It is proper not to distil lo dryness. •'-*• 

This process is first tneniioned by Lully. The liquid ,'3 

procured by means of it has been luually distinguished "• 

by the name of alcohol. 

Alcohol is said lo have becu dtscovcrcd, or at kast 
first accurately described, by Arnold de Villa Nora, 
who was born abonl (he end of the thirteenth century. 
This chemist, who was professor of medicine at Mont- 
pelier, first formed tinctures, and introduced them into 
• nedionef. 

The spcciBc gravity of spirits, as highly rectified »s Strtofth d 
possible by repeated disiillations, seems lo be about J^j[3!*" 
O'620, at the temperature of 60'' ; but ihe aicohol of 
cnmmerce, which is nothing else than rectified spirits, is 
. seldom under -SSTl. By means of salt of tartar Mu- 
schcnbroeck biougbt it as low as *815 ; but, in general, 
the alcohol concentrated by ihai process is not under 
- *S2I, owing to the weakness of tiic spirits employed, 
liven at the specific gravity "815 the alcohol is by no 



• Scrlhiipraccu dcKrikd by HnfTniii: at new, ia hit Oiurvjlltn 
Fiji'CijB. Scfxf.p. 36. publUhcdin 1711. 

t He hu uid aim to hi*c been ihc fim who obciuicd the oil of lu 
pontine. He frocurcd it by diHiliing lurptminc, ind rmplojtd it *i 
(uIventuftutnL 






means pure, still confining a considerable pertiond 
water. Dr Black, hy repealed distilUtionsoff noniic 
ot lime, obiaiiied it ns low as -SOO; but it wai Lotria 
of Pricriburgb who lirst tiit u,.on a mctfrad of cbtBuiBg 
aJ CO ho I in a Mate of abtalme punlT> or ai leatlraj 
ncBrlj lo. His process \v^\ publi»lird in I70n* 
(he !.amc year R:chr«r made known another, by whid 
the «air.c puiificaiiorv wasaccompitshcd wilh >tUlgi 
facility +. 

The procet* of LowJi* is m follows : Take a qunii^ 
of fixed alkali t perfectly dry, and 6t)ll marm, andni 
Ij fill triih it a rciori. Upon Ihis pour such a ijuxntii^ 
of alcohol (pieitDUsly brought To '831 by meamot mH 
of tartar) as can be aUorbed by the alkali ccmplettJj, » 
.lliai llie whole (.hall have ihe appearance ot a »oIid man 
without any alcohol ^wimining aboT«. In gciieial, ihe 
pioporiioB ou{j,hl to be tuo parl& alkali and one pait al* 
cohul. Allow iliis misiiirc to remain for 24 hours, and 
then distil by a heat ^o nioderait, that about [wosrcotidl 
clapK between Ibc falling of the drops of alcohol hi^ 
liie beak of ihe receiver. When this tnierval ircrrsst^. 
the receiver musi be tliangtd ; for it is ft »ign that A 
the strong alcohol has come over. What cornea o 
next is wckcr. By lliis process Louiiz obtained aU 
cohol of the specific gtaviiy OTQl at ilic temperaiult 
of 6S». 

When Richtcr repeated ilie cicpcnmenl of Lowiti, ha 
reduced the aJcoliot to the specific gravity 0-102 at the 
ten>i)eraiuie of (>&% but could not bring it any loner. 



] 1 prctuinE In the italt fl luVcirliOi 



upon trial, that the following method, which n"p-nr.^ 
itich more expediiious, answered equally well with 
of Lowili: : He exposed a quantity of the salt cal- 
mariatfi nf lime lo a red heal, reduced it to powder, 
and introduced it white yet warm into a retort, and 
^ured over il at intervals a quantity of alcohol, of 
0*821, nearly equal to it in weight. A violent hcnc 
W*s produced. The retort was put upon a sand-bath, 
a receiver adjii«ed, and the liquid made lo boil. The 
a>It was dissolved, and formed with the alcohol a thick 
•oloiion. The portion that had parsed over into the re- 
ceiver was now poured back, and the whole distilled 
by a genilc boiling nearly to dryness. The alcohol ihsit 
vame over was of the specific gravity 0192 at the 
temperature of (iS*. 

2. Alcohol obtained by ibese processes is a Irnnspa- Propertic*. 
rent liquor, colourless as water, of a pleasant smell, and 
a strong penetrating agreeabit taste. When swallowed 
it produces intoxication. Its properties differ some- 
what according to its strength. When procured by 
Lowilz'sor Richler's process, we may distinguish it by 
the name of pun alcoho!. as no method known can de- 
prive it of any more water. Wh<n the specific gravity 
is higher, the alcohol is contaminated with water, and 
the proportion of that liquid present increases with the 
specific gravity. Chemists, in general, have employed 
this impure alcoho], or this mixture of alcohol and wa- 
ter, in their experiments ; and as ihey hare too often 
neglected to point out the specific gravity of the spirit 
used, we are ttill in some measure ignorant of the pro- 
perties of this important liquid *. 

■ F«lu«ah^ w*i one of the Tint who ■Keriuncd nine of chc re- 



COMPOUND COIiflUSTISLES. 

B»^ I'- 3. Alcohol is excecdingl)' fluid, and bw never b 

frozen, tliougli it has been exposed to a cold to g 
that the thcnnomeCer stood at —OO"- ludeed, 1 
Wnlkcr simk a spirit of wine ihcrinomeier lo — ei^ 
wilhout any appearRnce of congelation. 

It >i a very volatile liquid. Fahrenheit foond d 
alcohol of the specific gravity of about -820, Ulheic 
^raiurc of 60°, boiled when healed lo 176°*. Whi 
I Aif the specific gravity 'Suu it boils at I13J". 
ihis Ileal it assumes the form of an clastic ditid, capah|| 
f resisting the pressure of tlic atmosphere, but whii 
' ycondeo&cs again into alcohol when that lcinper>lDr«iii 
■Mteduced. In a vacuum it boils at 30", and ezhi&M 
^vtbe same phcnomctka : u that w>re it not foe ihc p 
■vsorc of the almosphere, alcohol would Always cxittU 
k .ihe form of an clastic fluid, as iransparcni and inriiiblea 
imoii air. This subjcci was first examined u 
■tltention by Mr l.avoiMecf . The fad* however, ittM 
been known long before, 

4- Alcohol has a strong aflinily far water, and jfl 
misciblc with it in every projiorlioti. The ipecitic gl 
viiy varies sccoiding to the pcoportioa of the twol^ 



RUtkililt jiroptrtiei i>ri1c»ho] wiih eiuinna. tti> alcohol «na lilt 
KiAc ^vii; -8)j It the ttnipcnmre of 48°. Sm 1^1. TrtMi. 

• p. ii4> Foutcrny infatmi ui that (he ificdfic gntitjitM 
It hijjMr iccrificil aLohol u O'^lgj, withnul ipccJjinf the ti 
rbc ciircinii|r ui DiUBit't hydiomctct (at tiiirit* (K 
Idiolian'i tkble, ^^ri* fnr.l }$.) aniwcn (o the ipeclfi 

|>' JJ*'> ThItiiMf be coniiitiTcd ubcjond ilia ttra]|ib(/ A 
phiA uiej. In Ocxnunr, bcTor* Lowitl't eiperiqia>t*i th 
[ akohnl KC'iii wliiani id have u^ecdcdo'Sal u 6G'' ; aad in 

j>mnioiil7 <oniidciiibl]r weaker. Tbe Iii^hen poini of Cbd 
bydrunieler coirciponfli w'rth ikohol of thtml ■Bj4 t J0". 
MMM iIm pureil ■Icobol of the ^eeific gnviij •jaq — X n pm't Cttt I 

• r/.;;. Trj™^ i :ij. toI. iiiiil p. 1. t /"e. a Ptjt. ijlj- 



{nkis combmed ; but, as happens in almost all com- ' 
unations, the specitic gravity is always greater than 
he mean of the two liquids ; consequently there is a 
DUttial penetration : and as this penetration or conden- 
ation varies also with the proportions, it Js evident 
hu the specific gravity of different mixtures of alcohol 
itid water can only be ascertained by experiment. As 
tie spiritous liquors of commerce are merely mixtures 
if alcohol and water in different proportions, and as their 
trength can only be ascertained with precision by 
deans of their specific gravity, it becomes a point of 
rerj great importance lo determine with precision the 
>roporlion of alcohol contained in a spirit of a given 
ipeciGc gravity : and as the specific gravity varies with 
he temperature it is necessary lo make an allowance 
'or that likewise. 

The importance of knowing witb precision the pro- 
jortion of alcohol contained in spiri ts of every specific 
jravity, has induced many dificrent persons to make 
experiments in order to ascertain thU point with cxacC< 
less ; but as ihey set out from alcohol of very different 
nrettgths, it is not easy to compare their results with 
:ach other. We have seen that tbe pure alcohol, by 
l^wilz's process, ij of the specific gravity -791 at the 
.emperature of cs". That chemist mixed various pro- 
portions of this alcohol with given weights of pure wa- 
ter, and after allowing the mixtures to remain for 3\ 
flours, took the specific gravity of each at the tempcra- 
isre of 68". The following Table exhibits the result 
»f these experiments. The first two columns contain 
llic proportion of alcohol and water (in weight) mixed 
logelhcr, and the third the specific gravity of the mix- 
tifc at he". T have added a fourth column, containing; 



I 



416 



COUFOOK0 CtfUMBTULXt. 



Bo^ It ihe tpedfic gravity at 00% the temperaCniid coamodj 
pr^iTcd in Ibis coonuy *• 




TkUeefth* 

•ircngthof 
Akoholof 



jmriovi 



AloiihJ 



iAU. 



lOOPsrtr. 



100 
90 
PS 
91 
96 
95 
94 
9S 
92 
91 
90 
89 
88 
87 
86 
85 
84 
83 
82 
81 
80 
79 
78 
77 
76 
75 
74 
75 
72 
71 



Wat 



1 

2 

3 

4 

5 



7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 



-■ ' ■ ' 



fcw 



Sp. Ofavity. 



rite*i 



M.68«.|tt>D9. Alfobi 



791 
794 
797 
$Q0 
803 
805 
808 
8J1 
813 
816 

its 

821 
823 
820 
828 
831 
834 
830 
839 
842 
844 
847 
849 

851 
853 
850 
859 
861 
863 
866 



^96 
1f98 
801 

804 
807 



IQO Piiti. ^p».Of«viQ. 



851 
853 
855 

857 



863 
865 



867 i 42 



870 



76 
69 

07 

66 



809 I 6i 
812 I 04 
815 I OS 
817 I 62 
820 I 61 
822 I 60 
59 
58 



825 

827 
.830 I 57 

832 B 56 
55 
54 
53 
52 



835 
838 
840 

.049 
^846 II 51 
848 II 50 



49 
48 

47 
46 



860 I 45 



44 
43 



Wtu 



41 



\ SO 
31 
32 
3? 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
40 
47 
48 
49 
50 
51 
52 
53 
54 
55 
50 
57 
58 
59 



mUr^iw^6e^ 



1 



80B 
S1t> 
872 
875 
877 
880 
889 
885 
8ST 
889 
892 
894 



890 
901 
90S 
905 
907 
909 
912 
914 
917 
919 
921 
923 
925 
927 
930 
932 
934 



'871 

874 

875 

879 

880 

889 

886 

889 

891 

89S 

896 

898 

900 

90S 

904 

900 

908 

910 

912 

915 

917 

920 

922 

924 

920 

928 

930 

933 

935 

937 i 



9 Crell'i jMMsli^ i796» i. soju 



^r ALCOaoL. 411 


1 


■ «4 1 "'"" "' 


VMp.l«, 


1 


1 tODPvU. 


Sp, Gntiiy. 


, icoPiru. 


Sp. CniriiT. 




...c^. 


W.t. 


1^68? 


itfio". 


Akoh. 


W»t. 


It 6f>. 


itte". 


, 40 
39 
38 


fiO 


936 


939 


19 


81 


974 


975 


fil 


938 


941 


IS 


82 


970 






t 


62 


940 


943 


17 


83 


977 








31 


63 


948 


945 


16 


84 


978 






^_^J 


38 


64 


944 


947 


15 


85 


980 






^^H 


35 


65 


946 


949 


14 


S6 


981 






^^H 


34 


06 


948 


951 


13 


87 


983 






^^H 


33 


67 


950 


953 


12 


88 


985 






^^^1 


32 


68 


952 


955 


11 


89 


980 






^^H 


31 


69 


954 


957 


10 


90 


987 






^^H 


30 
2D 


70 


956 


958 


9 


91 


988 






^^H 


71 


957 


960 


S 


92 


989 






^^H 


se 


72 


950 


962 


' 7 


93 


991 






^^H 


1 s^ 


73 


901 


963 


e 


94 


992 






^^^1 


26 


74 


063 


905 


5 


95 


994 






^^H 


25 


75 


965 


987 


4 


96 


995 






^^H 


24 


70 


966 


968 


3 


97 


997 






^^H 


23 


77 


968 


970 


2 


98 


998 








22 


78 


970 


972 


1 


99 


999 








21 


79 


971 


073 


— 


100 


1000 








20 


80 


973 


974 














The Importance of this object, both for the porp 


OSes 


f revenue aad commerce, intiuced the British Govenf 




aetit to employ Sir Charles Btagden to injtitute a very 




»inute Mid accurate seilesof experiments. An account 




^ these was published by Blagden in ihe Phiioiophi- 




tml Transactions for IT90 ; and a set of Tables, exhi- oOiuo'ioir 




baiifig the result of them, was drawn up by Mr Gilpin, blw. 




|»ho had performed the experiments, and published in 




Ibe Philosophical Transactions for 1194. The follow- 




pig Tabic, extracted from these, contaiDS the specifia 




gravity of diflcrent mixtures of alcohol and water at 




Foi. II. O d 


H 



water. From the pfecediog Tabk, we aee 
of -825 is composed, of .89 pore alcohol 

11 water 

100 



I ^ • 



8» 


aoSaaaiaaUUicoot-r-r- 


-*ar-io-i>.nbo-tco!Oop*ci 


Is 




la 


mmmum 


11 


mmmiim 


u 


mimmm 


i! 


mmmiim 


85 


mimmiim 


8" 


mmmmii 


^1 


miimmii 


1 


°S S S S ?. S g 2 ? ? i 2 S - §1 



4t3 
Chip. IV. 



coMPotmo ^ommjmBtnm 





J 

I 



s 






8 



i 



AOiaicioiaoiSpicia 



I* !• t* 

^ 01 O 



- I- *» 



5* 



*il 



I 

8£ 






f^ ai f* m e^ 

an fW "S^ ^ «| 

01 01 Ob 01 a 



oiSSoiSSsftSS 



o 01 01 01 oi^o aoioaAAibtt 






iA«i««oir'^^^*S** 
oSoiQoioioioioiSS 




S 



Mo5(»F^cip«iAet#««o^iQ 

0iOr**Am*^0ir"#0IO9P«^<<i 



oioioiaiaiaooioioio 



ss 




85 



r"QO>-»^r»ooAao<^ 

OOidOOlQOkOIA 



«t a o c M 01 

t* A O •> O • 

CO « ^ 01 o r 



Ob 01 « 



1*^ 

§5 



-f^C«pHOt«'<ro«jbioO« 
^ MCcrtinco — oie^Qc 
— if-tpHpooocbaoioi 
OkAAOkaiabOiflOaoaico 



Em i» 

« 9 «D 



e .• 



•^•^<ooo'*»t*o»Oiai 
Oii*«Ok««cfbOr'-Mf>*4 

— OOOOOkOlCObOb 

oiObAOk9iaOfl04»«« 



i^ i£l « 9 lA 

oD e r- 9 M 

r* o «» f^ c 

(» (» fd • » 



5 
S 



o»no«oo«no«no»no%nQinc 
cf)M-t^tn»nfo<or"i*QO«oiaio 



^'' 





AtCDHOl. 


OuP. IV. u 




2^ 

Is 

ii 


aaoioiSdoiooioioi 




jf!gs;K2Sgss 
sss.tsssss5; 


-^1 
11 






SSgPSSSSSSS 

chOiOictaiaoiaaaiOi 


11 

S8 


— 0.003*«"«0*^ 


1^ 

is 




1 


O * O) O JJ O ■«■ -1 ^ J- ■© 


r-Oi«)Oa>«t-ooDmm 

OtOiOOiO>cio>OOiSiOi 


II 

88 


oiaoioiaaaoiaoiaoaao 


J fssssssss SPSS gag 


1 


E~ 


■^ 







4W 



eOMFOOVO COMBUSTIBCBfff 



Bopklf. 



Uf 






to* 



J* 
::8 



comer. er)ei^eiM^-«OQ 



I- 4b 



ei I 



^ ^ «n «^ >r, CI ^ ^ 

00 oo r- r- t- r- <o ■''. "O 
oofiooooooooooooD oo fio oo 

0^00>OC»OabOw Ob 



ol 

en 



• 


CI 1- eooo er. O 


<0 <0 00 


« kT. 


1^ 


^ O 1- eo Ok -^^ 


r- o 


«« , 


^ <* 


•♦■ eo « «o * ©1 




o 


C.O0 


M e\ 


00 00 00 00 00 00 00 00 oo 


1- r- 


o 


O: O P» O I> 0^ 

• 


Ob o 


Ob 


o a 


■5 S; 


00 ;c cr o o r- 


•HfO 


<o 


•n fcT. 


-^ ^ 


O 1- CO 00 N ^ 


r- 00 


o 


a 00 


^ ? 


'-^ C O Ck OiOO 


r* (O 


u^ 


•t « 


4 M. 


oo 00 00 «- r- r- 


r- 1- 


1- 


r- r- 


88 


Ck O) Oi O Ok o 

• 


a o 


o 


o» o 


• 


o fN r- <o c o 


O Ob 


-Ti 


to er 


•^ ^ 


VO O cr. (C 00 O 


- o 


C OO V 


'-■ If 


00 00 1" 'w *n »n 


^ en 


r« 


O C: 


— ^ 


r- 1- f- ♦* 1^ r- 


1- r- 


r- 


r- <o 


- o 


c^ c^ o» a o 0) 

• 


Cb Ob 


Ob 


a Ob 






:.8 



■5 t, 






S8 



*n»ei'f*'^^'*o<ooooo 
CO 4n I- oo oc oo r- »r> er. c 'C 
O »rb *h CO <M -H o Ci oo I- m 
i-r-r-i-i-fr-^oo^oo 

ObO^CbCObC&ObCbCbCbO 



000>00»OI-ClO^-t'CI 

i-^i-4WiHar-»n<Noo-*»Ci 

•fcr. •N-wC^OOl^^O'^'riP- 
C)Ok30»0bCbO)C>Ob0iC& 



o 'or-ooo'nr-ootor-^o 
cooo-roi^enoo^foo ♦^i 
'NO o. 00 f- kn '^ ei ^ a oo 
I- I- yD o <o 'c o r <o »n ko 

OiCbC'OkCbObQObObCbOb 



"3 J: 


1- o 


o 


CO 


o 


<M 


<M 


CI '^lOQ 


r- 


-^ ♦^ 


<c •*« 


o 


'O 


OJ 


r- 


CI 


O O CO 


<o 




O 00 


1- 


\n 


•* 


<NI 


9^ 


C. OO o 


-* 


O X) 


<o 


'O 


<o 


O 


o 


»o »n it; 


»n 


•oO 


a a 


o 


Oi 


a 


Ob 


Ob 


Cb Ob Ob 


Ci 


* ^ 



















I" 

f 



O^COO-*«»rtObCl»^ 

r-cooo'^ioO'^<oob»H 
kn^ciMaooo^'^*-*, 
to o <o o »'*. »n »n w^ %r. in 

OObOiCbOtCbObObObOb 



o 




















" 


». ' 


»n 


o 


\n 


o 


»n 


o 


*n 


o 


m 


o 


M 


CO 


"* 


•*• 


in 


»n 


o 


^ 


r- 


r-oo j 



r 



|B)r the excise Uwt tt present existing in this ceun> ' 
ft ihe dutj on spirits is levied by the bulk, esiimatcd 
iS psrticuUr sticnglb, to wliicli all spirus of whatever 
[cngth arc brought by means of a set of lables caicu- 
Ipd. Tliis &lien{rth is regulated by a very inconvcni- 
|; hydrometer, iovcnted in njO by Mr Clarke*, 
|ce wliich lirue it has undergone various changes and 
[proveinents. Thisinslrutticnt was adapted to a very 
jkutd kindof language, which had previously come into 
pimon use aaiotig dealers, and seems from them to 
kve made its way into the excise laws. A mixture ot 
|ua] bulks of alcohol and naler was cMed proof sp^ 
'i, sod sometimes double ipirit. Clarke's hydromeiEr 
^sisisof a ihin coj^per ball, lerminaling above in a 
Bl( slender stem, ai^d below, in a mctaljic builon, to 
pep i( perpendicular. It is so light as to swim in pure 
fcohol. There is a mark upon the mtdd'e of the slero; 
od small weights accompany the instrument, to be put 
n in order to suit the various icmperaiurei of the li- 
raid. There is a weight marked proof, so adjusted 
pat when it is placed upon ihe stem along with the 
broper weight for the temperature, the stem sinks lill 
lie mark on ihe middle of it is on a level with tbe sur- 
Kc of the liquid. 

From ftn act of parliament passed in I'OZ, we leani 
bat, at the temperature of 60°, the specifi^c gravity of 
woof spirit ought lo be OSIB. But Clarke's hydro- 
peter, loaded wiih the proper weights, sinks lo the 
park indicating /'^on/'in spirits of tbe specific gravity 
1-920, at the same lempciaiuce. From the table oi 



• See ihe Gill Jtittipiiono/it in fUl. 



eoMrooHO (!0NttriTiBi-ls. 

Lowi't, given ibove, we learn ihil s nixtuit ofeqU 
Wrights of water ind pure iteobol has the specific |Tfa 

vity -on at 60°. The legal proof sptril differs buiru. 
tie from ihisi Ctirke't proof contiiu of 49 piTU tf 
pure alcohol and 51 of water. The ne«r coincidrace 
of these numbers to the truth, indicates s considcnbk 
approach to accuracy. Had Sir Charles Blagden mijr 
choice of an alcohol of 'BOO for his aUndftrd, the sped*') 
lie gravity of proof spirit would have been foQnd utit- 
viatevery little from that of Clarke. But if by ptorf, 
spirit were to be understood equal 6u/it of water 
alcohol, BS was doubtless the case, then both the 
and Clarke's proof differ very far from tlie truth. 

The strength of spirits stronger thav firoof, or owiv 
proof, AS it is termed, is indicated on Clarkt's hydroEne. 
ter by the bulk of water necesisary to reduce a givM 
bulk of spirits to the specific gravity denominated proeC 
Thus, if one gallon of water be required to bring 20 
gallons of the spirits to proof, it is said Xa be eni- te (Q 
tntrfroof; if one gallon of water be necessary to briW 
15, 10, 5, or 3 gallons of (he spirits to proof^ its 
■aid to be one to 15, one to 10, one to 5, i 
respectively, over proof, and so on. 

The strength of spirits weaker than proof, or sn^ 
proof, is estimated by the quantity of water which il 
would be necessary to abstract, in order to bring ibt 
Bpirils in question up to proof. Thus, if from SO git 
Ions of the spirits one gallon of water must be abstract- 
ed to bring it to proof, it is said to be ont in i 
proof i if from 15, 10, 5, 2, £tc. gallons of the i^ 
rits, one gallon of water roust be abstracted to bring it 
to proof, it is said to be respectively one in If 
10, one in 5, one in 2, &c. ttnder proof. 



M/coMt^ 



4t^' 



rhe fdlM^g TaUe points oat tlie specific ptntf ^Cft•^^r> 
piiits of the 'Varioos strengths indicated hj Clarke*i 
Irometer at the temperature of 60^ *• 

Dtgrecik Sp. grairity. 
in 2 M44 &A)MfB. 

— S 0543 

— 4 9458 

-^ 5 9424 

— 6 0385 

— 7 0304 

— 8 9344 

— 9 0334 

— 10 0320 

«-*15 9286 

~20 9265 

TtooI. ••• 0205 

tO20.«.. •.9102 

— 15 9135 

-^10 OlOt 

-^ O 009S 

^■^ o« •••#••••••• •••00 #1 

— 7 9047 

— 9000 

— 5 8O01 

— 4 8013 

— 3 88l7 

— 2 8590 

Alcohol 8S38 

\ retnoTC all confiision from the duties ctt spirits^ 
ij ought to be levied by ihe weight, and not by the 
Ik. This might be done with sufficient aocnncjr 



^;WilMi*t TaUeit^ i 



420 COMPOUKD COMBUm BLSS. 

^^^ ''-. either by actaal iveiehing, or by oonstmctinf tMa 
<■■ y ' lodicaung the weight firom the bulk and speci&c fpm 

vitj. 
Actioo of 5« Neither common air nor oxygen gas hat any ac- 
■aTaBdco^ tion on alcohol in moderate temperatures, whether is 
^^ the liquid or gaseous state ; but in high temperatorci 

the case is different. When set on fire in the open air 
it burns all awaj with a blue flame, without learag 
any residuum* Boerhaave observed, that when the va- 
pour which escapes during this combustion is collected 
in proper vessels, it is found to consist of nothing bot 
water. Junker had made the same remark : and Dr 
Black sus{>ected from his own observations, that tbc 
quantity of water obtained, if properly collected, ex. 
cceded the weight of the alcohol consumed. This ob- 
servation was confirtped by Lavoisier ; who found that 
the water produced during the combustion of alcoboi 
exceeded the alcohol consumed by about (th part*. Mr 
Saussure junior has shown that 100 pans of alcohol 
when burnt, yield 132 parts of water f. A proof that 
it contains a conkidcrable proportion of fhydrogen ass 
constituent. 

When the vapour of alcohol is mixed with ozjgen 
gas in the proper proportion^ the mixture detonates 
when presented to a lighted taper, or when fired bj 
electricity, as a mixture of oxygen and hydrogen ga&et 
do. This fact seems to have been first obser%'cd bj 
Dr Ingcnhousz, or at least his experiments on ether 
appear to have led to it t* Tlie density of the vapour 



• :; Pur, i:fi,f 4'}:.- 



^^^Bliet is considerable, and hence ihe quanlitj of Chjp. IV. 
B^^ii necessary lo consume it is great. The pro- 
.8 of the cotnbusiion are w;iler and carbonic acid *. 
. Alcohol lias but little action un the simple coni- 
tastiblcs. On hydrogen, carbon, and charcoal, it docs 
Bot appear to have any effect. 

It dissolve&a lilile phosphorus when assisted bjr heal. Phonphu- 
This phosphorized altohol exhales the odour of phos- hoi 
phureted hydrogrn gas. When a little of it is dropt 
jblo i glass of water, a flame instantly makes its ap. 
pcarance, and waves beautifully on the surface of the 
kfsRrf. This phenomenon, which is occ^ioncd by 
the emission of a liiile phosphureted hydrogen gas, 
tn only be observed when the experiment is performed 
, a dark room. 

When sulphur and alcohol arc brought into contact Sulpliurrt. 
^n the state of vapour, they combine and form a reddish 
coloured liquid, which exhales the odour of sulphureled 
Avdrogrn. Tbis compound was first formed by the 
iCount dcLauraguais, who employed the following pro- 
.ccss. Some flowers of sulphur were put into a large 
i^Iass cucurbite, having a glass vessel in its centre cou- 

! Mining alcohol. A head was adjusted, the cucurbite 
placed in a sand-bath, and heal applied. The sulpbur 
Wat volatilized, and the acohol converted into vapour at 
ionce. Tbc*c meeting together in the head, united and 
llortned ^ red liquor wanted t- It was supposed by 



* Ciuikihaulu, Nidialuui'e 
t Brngiutetll, jU*. A Clia. 




eoMrouK ti eoHBtfsTtBtEf. 

ch«inijtt that sulpttur cuinoi be dissolved in deehi 
except hy a similir proceii * ; but from the late 
rimenti of FavrC, ihii does not appear to be tbe ( 
He digesled, during 12 liouis, one part of 6o«i 
lulphor in eight pana of alcohol, of ihc spatifii 
vilj 0-837, in a htat not sufficient 10 produce bo 
The alcohol assumed a yellow colotir, and ac^uirfd 
tmell and ra&teofaulphuretcd hydrogen. Another pi^ 
tton of the tame alcohol wasdigestcd for aitionihiOt^, 
en sulphur. The effect was the same. On Itji 
Cohol of various sirenglhi froin '817 to *S07, be 
that the altohol acted with more energy in pro| 
to iit sTrengTb. 

The sulp!iurered alcohol prepared bj Lsartgintfj 
method, contains about ^th of sulphur. Tha tnlplw 
is precipitated by w. ter. 

1. Alcohol dissolves the fixed aUcftliea very readily, 
and forms with ihem a reddish- coloured acrid 
It is from this wlutton only that these alkalies ou k| 
obtained in a siale of purity. When beat is applied ft 
it the alcohol mij be distilled over. Ii appears 
ever, 10 be partly decoinpoiei! t bni the nature of tbi 
products has not been accnraicly ascertained. Attme, 
Ub also combines -with alcohol with ibe assitiaoce tt 
Ileal : but at a temperature somewhat below the bofl. 
mfi point of alcohol, the amnicnia flies off in 
«f gas, carrying with it, however, a liiile alcohol in ■••. 

8. None of tbe earths are acted upon bj alcohol, 



• Seethe £/>wmA 



.VofihcDiJDoAtideBr.iiLitr. f<matfl 
t Gehleo't J«rr. ti. J43 



ALCOHOL. 429 


m slrooiitn and barjtes be excepted. It absorbs a. Cl.»^ iv. 


ool iu own weight of nitrous gas, which cannot after- 


irwds be expelled by heat J. 


9. Of the acids, the sulphuric, nitric, and oxymuri- AtU^ 


tic, decompose alcohol ; but all the other acids are so- 


uble io it, except the metallic acids, phosphoric acid. 


tod perhaps also ptusstc acid. ^ 
10. Alcohol is capable of dissolving a great many Siia. 




be ^uantiiiei soluble, is exhibited ia the following 


PaWesV 


I. SMbtlancet dutohed in large ^antiliti. 










tan. 


140 put! of AL 




Oxysnlphaic of iron 






Nitrate of cobalt t 


54-S'' 


£40 parU 






54*5 




alumina +"'.".'.'.*." 


54-5 


240 - 




litncl 








magnesia f 


180-5 


694 




Muriate of zinc f 


54-5 


240 




aluminat 


54*5 


240 




magnesia t 


180-5 


1313 




iroDf 


in 0-5 


240 




copperf 


I8O-5 


240 




A^tat* nF Ipad + . . 


154'5 






£SIKtBIQ Vi lt*U p .......tl... 












Nitrttt of zinc decomposed f 




iron decomposed f 




bismuth decomposed f 








I Pr «lty, L 3:9. 




1 • Morrean, J-r. J, Piji. tjts- 'M 


{ J Withcriog,fiJ/. rr«..UxtLj3fc ■ 



430 



COMPOUKD COMBVSTIBtKS. 



Book II. 
DirWan II. 



IL Substa'fUes distohed in smaO ^mantkiiu 



Names of the Sulttancet. 



fl40 pam of AkM 
iCtlieboil^ 

■ 

I 



Muriate of lime f 

Nitrate of ammonia f • 

Oxy muriate of mercury ••••• 

Succinic acidf ••••• ••• 

Acetate of soda t ••• •••• 

Nitrate of stlverf ••••••• 

Refined sugar f ••• •• 

Boracic acidf ••••• •• 

Nitrate of soda f ••••••••••••• 

Acetate of copper f •• 

Muriate of ammoniaf ••••••• 

Superarseniate of potash f ••• 

Oxalate of potash f 

Nitrate of potash t ••• 

Muriate of potash f •••••••••• 

Arseniate of soda f 

White oxide of arseniq f ...^ 

Tartrate of potash f 

Nitrate of lead } •••...• 

Carbonate of ammonia § •••• 



240 ptm 

214 
212 

ni 

112 

100 
59 
48 
23 
18 

n 


7 
5 
5 

4 
3 

1 



III. Subftances insoluble in Alcohol. 



Sugar of milk 
Borax t 


Sulphate of potash f 
sodaf 


Tartar + 

Alumf 

Sulphate of ammoniaf 


magnesia t 
Sulphite of soda 
Tartrate of soda and 


limef 
barytes 5 


potash 
Nitrate of mercury f 


iron f 


Muriate of lead f 


copper f 
silver f 


silver J 

Common salt f 


mercury f 
. zinc f 


Carbonate of potash 

soda 



ALCOHOi;. 491 

These experiments were made cbieflj by Macquer ,Cha y.nr. 
nd Wenzel *• The alcohol employed by Macquer was 
tf the specific gravity 0*840. Wenzel does not give 
he density of his alcohol ; but as he compares it with 
hat of Macqnert we may suppose it nearly of the same 
trength. AjS the'solubility of salts depends upon the 
drength ol the .alcohol employed^ the experiments of 
ihese cheniists must be considered asdefoetive^ becaose 
they have confined themselves to one particular density. 
This defect is in part supplied by the following very 
valuable Table of Mr Kirwaa% oonstmcted ficooa his 
own- experiments f • 



• VtruMudiHi^ft, p. aoa The nhbailf flf all the ttki iiitik«d f 
WM aaccrtifiied by Wands dio*c WMtkad U ^ MtcqiMr; and thott 
nuked {» by Witheriog. 

t Om Mmtrtl WsUr*, p. SM- 



coupoDHD comoimus. 

: Solubiiity of Sakt ia 100 parti of jVnh^ of ^ma^ 
Dtantui» 



Siltn 


aUUc/ 1 


0>900 


0-872 


0-848 


0*834 


0-811 


Salphmte of soda 


y 


0- 


0- 


0- 


0- 
0- 


Sulph. of magneiia 


r 


1- 


0- 


0* 














Nitfjte of potash 


ri6 


1 

6- 





0- 
0-38 




0- 


Nitrate of soda 


iO-5 


Muriate of potish 


4-62 


1*66 




0*3I> 


0- 


MurUbofsoda 


5-8 


3-«7 




0-5 




Muriate of ammon. 


6-5 


4-75 




1-5 




Muriate of magne- 
»ia dried at 120" 


21-25 




Z3'75 


3a-25 


50- 


Muriate of barytcs 


1- 




0-29 


0-185 


0-00 


Ditio crystallized 


1-56 




4'12l 


0-92 


0-oe 


Acetate of lime 


2-4 




4- 75 


4-« 



When alcohol containing certain saline bodies isn 
lution is set on fire, its flame is often tinged of dUTeil 
colours according to the body. Tbusnitiale of stroatiJ 
tinges it purple ; boracic acid and cupreous sails ti 
it green ; muriate of lime gives it a red coloor ; 
aod oxymuriate of mercury a yellow colour. 



Al* Different opinion* were cntertaiited by chemists Ch^ I 

II the nrilure of dcohol. Sulil iHought that it was Compvu 

,[»o«ed of a Very light oil, united by means of an add '"*"' 

a quaiuitv of water. According lo Junker, it was 

m{>osed of {ihlogiitlon, combined with water by means 

in acid. C^nhcuser, on the other hand, afGrmed that 

ontatned no <icid, and that it was nothing else than 

'e phlogiston and water. Bnt these hypblheKS were 

r* ass^riiont supiwricd by no proof whatever. Laj 

isicr was the fir&t who aitempied to analyse it. 

Sc tel fire to a quantity of akolio] in close vessels 

mesni of the following Bpparaiui: BCDE (lig. 13.} 

vessel »f marble filled with mercury. A is a strong 

a vi-tsel pl.iccd over il, filled with common air^ and 

ibic of containing abom 15 pints ^FrenchV Into 

vessel is put the lamp R filled with alcohol, ihc 

ligtit of which has been esacily deiermined. On the 

ck of the lamp is pnl a sui^Il panicli: of phosphorus. 

.c aiCKury is drawn up by suction to the height IH. 

lii glasi conimunicaies by means of the pipe LK with 

plher glassvestel S tilUd with osygcn gas, and placed 

:t a vessel of water T. This com niitni cation may ba 

t up at pleasure by means of the slop-eock M. 

Things being thus disposed, a crooked red hot iron 

ire is thrust np through the mercury, and made to 

Uch the phospliorus. Thisinstanlly kindles the wick, 

id the alcohol burns. As loon as ihc Same begins tai 

row dim, the srop^cock is turned, mtd a ctmiimunica- 

opened between the vessels S a.nd A; a quantity 

oxygen gas rushes in, and restores the brightness of 

Bame. By repeating this occasionally, the alcohol 

f be kept burning fcrsomc lime. It goes out, hew-- 



COMroOM D COHBOmtLES. 
^■LHbK, HOtwithitKnding tlic fldmttnan ol um 

tW femlt of t^iis experiment, which Mr Iati 
efltd* jTe»i number of time*, wi^ nii>Ht^\: 



..1O-10S.T gnnnttnj 
Oa.j|uign eonsumcd •io-:rOi<o 



T0al...„ 107-2143 

AAsr the coBibuittonF (licrc wai foond in thc|)l 
vokI 115'41 cubic incliet of c^tbotiJc nid g«i, 
woght of which waj 78'l 102 graitit troy. T>i*rei 
ttrrae foond » considerabte quinthy of w« 
VomI, but it was not pontble to collect aid wngh 
Mr Lnoinn, however, csiiinHtrd its wcij^fit a 
gntai ; ai he concluded, with reaton, that tbcftl 
«f the tabiiances cm|)Iojed wcr« *ti)l in the nt 
Haw (he whole cnntcnts of ihc vMtcl consisted ofi 
Woe acid gas 2nd water ; therefore ihe carboDic 
gn aid water together must be erjual to (be axyfiet 
wd alcobol which had been consumed. 

Bm lS-1192 grains of caibonic acid gat co 
■onfiag to Mr Lavoisier's calcolaiioD ", S5-Z1J> p 
of «x7vcn: pri*506 graini, however, of oxTgengU 
; therefore 35'^'?' grains inusi bm 
D forming water. 

3^*221 grains of oxygen gaj require, in ai4ctto 
WaRT, t'0i9 graina of hydrogen gas ; and ibe 
«f wwer farmed by (his eoi-nbinaiiao is 41'265 |n 
Vtfdkcrewere found S<> 003 grains of W4ter n 
*fa^vr«e1; therefore 41*83 grains of wa|«r miHl 



d ready formed in the aleetin]. 



s 



ALCOJFlOL. 435 

h follows from all these data, that the 7fl'7083 grains Ci»i>- '^ 
IsCaleoholy consumed during the combustion, were com* 

of • * • • 'J2'4d carbon 

0-03 hydrogen 
47'33 water 



767 



Such Vi^erethe consequences which Mr Lavoisier drew 
frotD his analysis. He acknowledged, however, that 
^here were two sources of uncc-r taint j, which rendered 
liis co'iclusions not altogether to be depended upon. 
The first was, that he had no method of determining 
the quantity of alcohol consumed, except by the diffe- 
fence of weight in the lamp before and after combus- 
tion ; and that tlierefore a quantity might have evapo. 
rated without combustion, which, however, would be 
tkkcn into the sum of the alcohol consumed. But this 
^rror could not have been great ; for if a considerable 
quantity of alcohol had existed in tiie state of vapouf 
in the vessel, an explosion would certainly have taken 
place. The other source of error wa.s, th'*t the quanti- 
ty of Water was not known by actual wtight, but bj 
calculation. 

To this we may add, that Mr Lavoisier was not war- 
ranted to conclude from his exjjeriment, that the water 
found in the vessel, which had not been formed bv the 
oxygen gas used, had existed in the alcohol in the state 
of water: he >vas in titled to conclude from his data, 
that the ingredients of that water existed in the alcohol 
before combustion ; but not that ihey were actUiJlj 



• Mem. Pjr 178 1. 

E e 2 



436 COMPOUND COMBUSTIBLES. 

Book II. combined in the state of water, because that comUi^ 
tion might have taken place, and in all probabilitj tt| 
partly take place, during the combustion. 

The alcohol emplojcd by Lavoisier was of the sped. 
fie gravity u*8293. Hence it contained I3fercm,d 
water. If we subtract this portion of water, and mab 
the requisite corrections, we &hall have the constitoeMi 
of alcohol indicated by the preceding analjsb nearlj u 

follows : • • • 49 oxygen 

34 carbon 
17 hydrogen 

100 

A result certainly far from the tnatb. From the ci. 
periments of Cruikshanks, made by detonating a mix* 
ture of the vapour of alcohol and oxygen gas, it followi^ 
that in alcohol the proportion of carbon is to that of bj. 
drogen as nine to one *• But this is not snfficicat Ib 
give us the component parts of alcohol with predsico. 
The subject has bee:i lately resumed by Seussore jo- 
nior, who has published a very elaborate set of ezpeii. 
ments on the analysis of alcohol. The alcohol wbid 
he employed was obtained by Richter*s process, aiid,fl{ 
course, of the specific gravity *702, at the teroperatmc 
of 6S*. He eoiployed three different methods of ana. 
lysi^ ; the first method was similar to that of Lavoisier. 
He burnt a quantity of alcohol in common air mixed 
with oxygen ga<, and ascertained the weight of alcohol 
and cxvgen consumed. The only sensible prodncH 
wete carbonic acid asd warer, the first of which ht 







ALCOBOt. 437 

rared, and the second he calculated. The follow- Chap. IV, 
is the result of his ezperimjcnt : there were con- 
Mimed 35t grains of alcohol, and 129*83 cubic inches 
»f oxygen gas, while 77*87 cubic inches of carboni^ 
ft^d gas were forrtled *. From this experiment, calcn- 
Ating iri"the usual manner, he deduced tluit alcohol is 

iposed of oxygen 47*296 

carbon 36*890 
hjdrogen 15'814 

100*000 1 

fomid, that when a considerable quantity of alcohol 
irrnb burnt, and the water formed collected, it contained 
% portion of ammonia. Hence he concluded that azote 
is one of the constituents of alcohol. 

His seeond method of analysis was to mix the vapour 
ftf alcohol with oxygen gas when the thermometer 
Mood about 70^, and to detonate the mixture by means 
off electricity. He estimated the quantity of alcoholic 
▼mpoor present by means of Mr Dalton*s formula, ex- 
plained in another part of this Work. To make the 
nixture capable of detonating, he was obliged to add a 
•mall quantity of hydrogen gas. The result of the ex- 
periment was, that iS*I9 grains of alcohol in the state 
of vapour consumed 75*88 cubic inches of oxygen gas« 
There were formed 46*69 cubic inches of carbonic acid 
MS, together witii a portion of water. From these da- 
ta lie calculated the ^mponent parts of alcohol as fol- 
lows: 



*Thewdghu and measoret mentioned in these ciperimentt are 
fireoch. 

tl>licbobio^/Mrr. Ttl %%S- 



439 COMPOUND COBVUSTUtXS, 

W'v^n. oxygen 3T36 

- carbon 4G'82 

hjdrogen 15*83 

100-00 • 

This result differs from the preceding, and ought I 
more accurate. It deviates, however^ verj far froi 
conclusiofia drawn by CruiV^hanl^s Irom a simtL 
of experimfiits. 

The third method of analj&is was to decempc 
alcohol by passing its vapour through a red hot ; 
lain tube : the products were a little charcoal, : 
oil, partlj in crystals, partly fluid, a portion of 
holding in solution acetic acid, ammonia, and i 
acid which resembled benioic, and a great quar 
heavy inflammable air, to which Saussure ga 
name of oxycarbureted hydrogen gas, and which 
his analysis, he considered as a quadruple compi 
oxyge!>, carbon, hydrogen, and asLote. The fol 
is the composition of alcohol as deduced from tb 

lysis :•• • ^.oxygen 37*85 

carbon 43*05 
hydrogen 14*04 
azote 3*52 

ashes O'O*^ 



loooot 



These results, though probably as exact as the ] 
state of our knowledge will enable us to go, are 
^e considered as exact. The absolute alcohol of 



f inctiiol|M*s fmn^. mA ^p. . t Ibid- ^ ^J,' 



.^oubilegs contains a jiortion of water ; and our igno- 
ce of ihe quaatitjr tenders every attempt lo analyjc 
>tiol uncertain, I do nolconiider the analysis of ihe 
•carbureted hydrogen as made by Saussure lo be cx- 
, The proportion of azote which he inters van pro- 
iy an error in ihe experiment. The presence of 
DODiSf however, in the water rrotn alcohol, seems to 
■ proof that aiole actually exists in alcohol, though 
pj-dportioQ of it is so small that it may have becif 
e«i from some foreign body accidentally present. 
bC it contains oxygen, has been proved by a very 
Otis set ofexperimenis performed by Messrs Four- 
,.Kid Vauquelin. When equal parts of alcohol 
slpfauric acid are mixed together, the sulpbu- 
d suffers no change ; but the alcohol is decom- 
&>eing partly converted into water and partly 
K:&^r. Now it is evident thai the alcohol could not 
9 converted into water unless it had couiaiucd 



I 



OF E TU£K. 



X.t9 alcohol is mixed with sulphtiric acid and k- 
^tber acids, and the action of the acid is as^iiited 
a^ty tbc alcohol is decomposed, and converted part)/ 



• Vkholum'i Mr 



COMFOrVQ OOMVOSTtBLZS. 

into a very light mlalile frajfr»nt liquor, known k^Ai 
axiae of ttler. The proprriiei of I he elher ( 
are sui>poted to vary s Utile according to the Mmtsa 
ployed : necorijingly et-ery pviiciilat kind U 
goi*lied by ihe acid used in it» pTepsrBtion. TW 
the cihcr obiained by means ofiulphuric acid itcaJW 
sulpburir tihir i ihal by mean* of oiinc wid, 
tthtr. It will be proper to consider each of these ^ 
cjes sepaniely, 

I. SULPIIOBlt Etheh. 

The method of making nilphuric ellurr is d«oiW 
in the dispensaiory of Valerius Cordus, puMiihed 
Nureflnberg about the yesr 1640 ; from whicft Coctrtf 
Gesner trariicrihed it into hi* 7>r/CT»nw KuoHjmi di Rft 
mfdih Secrctit. published in 155?, where ii it 
OltKm yilntiidwiee". It appears lo have been ki 



• Whoe^rrwillcnniidrr tbefonn«la gWm fur prqwiHff lliii 

the ilaUiJi^ tUi of ihe modirtii. v.i lh*t il umw hm hetn a aani 
th,UI,rthr. md ■«■'» «!•/ f W- The Ulowti^t » iIm tMMp>|i 
iwr, MqDMr<) ^ H"ffmiD.trinn whomh« Wo ukrn rbcbi 
facn [cq«cling the fcnowlcilgc ■J«liir poiKucd \>j til* 
wriicri. '' Recipe viniardcHinacerrupilc irrniblln 
olei »itrloli »n«rri iJiniunJem. oiiwe in «inli. .'■ liit", &p«w|M 
crliHun pkrnni .njiu.to utifitio.* lulo uptitiiu .^ofiooiB (l»dr, 
(mite ir» ptr intcjTiim n.enKm »<" «'■<'-■ D""* HTi.nde in <• 
tui. CD) w imnicdute ■nnnttm itnuliieam, niJB" Bjaram ahiki 
^ncdeiodcm pir.im(oni«eni, »c diniidwm rJM pmtm elnoe abl 

vncUi KI nni wdpiEia qu4u infuilist. Ui *cin taiiiu btic fiiU, |H«r 
b'lpnim M«ti« I ik pdum Tioiini iJi.ipi( rJf o iKrudrt. t-um eitr 

•aimi p*f bUnnon inloMt "uci*t «t» vioi wt', r""' ^' 1"'*' "^e*' 



stheh. 441 

-tfumgh not in a sttle ofpuriiy, both to Basil Valen- c^'p- '^-^ 
'tine and Paracelsus. But in the wrilings of dieinists 
poblished about the end of the 1 'ill ccnturj, I have not 
been able lo find any traces of it ", except in those of 
Mr Boyle. He was evidently acquainted with it, as ap- 
pears from diSfrcnt passages of his writings i-, though 
be no where describes it particularly. But it was a pa- 
per in the Philosophical Transactions for nan, by a 
German who cniled hiitnelf Dr Frobenius, describing 
aercral ofils most singular properties, thai first drew 
the attention of chemists to this curious litjuor J. In this 
paper it first received the name of e-ther. The German 
chemists long distinguished il by the name of naphtha, 

1, Sulphuric eihcr is usually prepared by the follow- Prepir*. 
ing process ||; A mixture of equal parts of alcoht^l atid ""^ 



cufurbitx 


patiem«ringM.aera)»o* 


" 'ppli"' 




umigMiM 


& MflMm atnbe anuHm 


ci.ib>>a, ,1. 


nr< nihil htimi.U >mpli<ii in 


rn.im.. tar 


& dlll)(enTU, ul isatm iti 


n.bi<i latii 


i m. Nam s hune ehulli. 



Ctr, in /Dtctcrin, of aiena mcdiim < 
«aCDO rcripicric eoquc pud magwn 
[I Claude. Auende dciaile ir.oduti 
kumiiJitMcni qrii rrlia* «« in tut 
fimdo (ppircit; BJhibhiiemptrm 
tBoderfrii, nc (trolliit mque i<l alei 
tin tttl^ric, KtUrv licni putn, Lcque prohbcrf, igiiin in reccptanluiu 
•yrciliatur, if (otuni vlcum ftidu ; toUl rnim lacillmc cbuUire. Turn 
«i(lebit duo totirii Mi in f, aqutimi niilcUn humorcm at pirguem ; ic- 
gnp}iu vein unum ib ilicro -iai;m, ira ut nih:l aqunim id oJco rctln- 
■nm. fimm iqumllialninicarfiniipit; Kgrcgi^oninkuinutuIieKm." 
'Tbe ttlnm ^'i/rwrt o./fr o! Lcn>rr>, liit iiiirantr.wTerji diffarat 
{ran ihu doiilbrd bj Guocr- (Sec hia Cu<ri iV Uijm'u, f. jci.) 

f Sec Shao'i Boyle, i. jjo. and i. 169 ; wliirrc the pruccu for making 
fflbCTt md tome of iii fntdl tnrur'kable proj>f nic'i arc ^ctailfd it length. 
t Pttt. Trot. IKIVT. iKj. Thi> paper it liiilc (Ik than ■ rhipKidT )n 
Aa BkhynilHlcal ttj\t. Ai ib< end of it ihcrc it 1 noic by Mr Gudficr 
(Hankwllt], Mr Bojie'* opmior, nieniit>iiing the ejperimenti romitrly 
B»*de upM il t>]t Mr Bofk snd S>r luae Newton. 

) Prabdlillt' procos WM fint pobliihcd in the Philoiophiral TiaiiSK. 




COMrOUMD COUMSTISLIt. 1 

fulpboric acid it (ml into Ihe rati^ lo which slnp It 
ivqcivei t* ihen luted, it ii pcopcr to kurnwr^ ibt re. 
ceivcr with ice, or at Icavl wiih cold water, Ilctm 
applied i iuid as suoo us ilie iniicturc boil*, thr cttv 
comet over and is coiidtntcd, and luni hi lu^^c ttn 
dowu the side* cK ihc receiver. As &oon ux ii laioodi 
to one half of llic ult^jlol tniploycd, (he ptiteru ttiU 
be tlopl. Tlic elliec ihua obiamed is nut cjuiK fiuii, 
almost alwajrscontAiiiing s Iiitir sulphoruu* add. 

This acid mxjr be Mparaied b^ pouring the nliS 
on a liide poia&b, miA distilling it over susiii hy a 
of a model Hlc ticat. Mr Diz£ •'IHi ois ih^i biaclt uside 
ol oiuigancic piuduc«s tliii ctfecl sliil nioii complatij 
than potash. All tliat u oceesiai^ is to mijc a qnsau- 
ty o( Uiik black oxidoii) powder with the iiupurc ether, 
and to let it rctiiuiii for «ome irn-e, agitaiinjj it i>cca.ii«t> 
allv. The Hiilpluiroii^ acid is couvrritd inio sulplwnc, 
»i)d ci>mhtnet wnU the mah^aneic. I'hc eilier is diu 
to be diitilled av«r by llic h»t □( ii water baiti*. 

The scpaiation of the liqaid tiotn lh« sutpbor 
acid, with which it U mixed, -,\ called the ttcti/itmtm^ 
of tht tthtr. The ustul meibud, and I ma^' udd ihftu 
best, is the followring, first employed bv Mr WoUei" 
Fill thrce-fnurths cf a bottle with the Impare ctber/ 
add a little watei mid a portion of ^bckcd liiiic. Aj[i- 
latc the boltlt with vioicace, and keep u fur sotne linOt 
in water before txkmjjom the crrk. If thr smell oftha' 
acid be not rctuovcj, add a liitic mere lime, am! a^ 
tate a second time. Decant off the ether loto a Ma(\, 
suid disiil it over f . 



'' Wyr. slti. Ifp* 



\ fna*, Ata,4i C^im. aU ^ 



KTHUt. 44f 

J ether procured by this process is not quite pure, Chap- IV._ 
ficr all the acid has been removed. The first 
l^oruon of liquid that comes over during the distillation 
Ea merely alcobal impregnaicd with a lilile elher. Com-t 
Oon eiJier ii iii reality a mixture of ether and alcohol. 
7b« usual method of separating this liquid is by mixing 
the ether wiili water, and then proceeding to disrillalion 
with a Tcry moderate heat. But Mr Lowitz has sliown 
that this method does not succeed. The following pro- 
cess yielded him an eiher much purer tlian any that had 
been previously obtitincd. Into Hi parts of Ct her, of the 
specific gmvity 'nain the lewipcritiure of 60", he threw 
dty powdered salt of tartar, till the last portions were 
no longer wctitd by ilie liquor. The tnixltue being al- 
lowed to digesi, the eiher was then diawn off. Its spe- 
cific gravity was now only "^ iti. liy this means it was 
^prived of the water whkh it contained. To lemove 
the alcohol, dry powdered muriate of lime was thrown. 
iaio the liquid in the same manner, as long as it wouhl 
dissolve. On standing, the mixture separated into Iwo 
porliona ; the alcohol holding the salt in solution sunt 
to ilie bollora i the ethf t swam on the surface. U'heo 
separated from the inferior liquor, its speciHc gravity 
was now only -032 in the lemptiamre of oo". It was 
therefore much purer than any former elher described 
bj diemisttt since it never before had been procured 
lighter than (J'ia5*. The ether thus prepared con- 
tains a little of the salt, from which ti may be freed by 
But in that case its specific gravity in* 



» l-VvilXiCrtU't Jaah,f;<]i, I 419, 



COHFOITKD C0UBT7&TIBLU. 

*5^"- ereiwi. The reason seems to be, that the pnreit 
lion of ilie ether Bssiime» the form of clairic flntd. 

2. Ether thus obtained it a limp<d and colouikuK* 
quor, of a very fragrant smell, and a hot pan^ent tutQ 
II is so volatile thai it can scircelj be poated fro* 
one vessel lo another without losing a conatdcrabttjMV 
tion of it bjr evaporation. When poured oot 
«pei> air, it disappears in an instant; and dtirtn^i 
P poraiton produces a very contidersble degree nf coll." 
r If a glass vessel containitig water, and surronnded "illl 
I '• cloth, be dipt into ether, two or three tiines, tni \tit 
T eiher each time be allowed lo evaporate frooi the cloili, 
I Ae water in the glus freezes. In the opr n air etha 
I boils at OB*, and in a vacuum at — 20". Were it 
flierefore for the pressure of ihc atmosphere it W( 
I tlways exist in the gaseous state. 

When e:iposed to the open air tt speedily aisu 
flit gaseous form. This happens, for inttanee, ifi 
little of it be pouted into a glass phial. The vafxy 
of clhcr displaces a considerable portion nf (he air ofti 
phial, and is not soon dissipated. IngcnlioiKz brfj 
shown ihar the specilic gravity of tliis vapour is vtrf* 
ronsiderable *. 

Mi Dalttin has fonnd it 2-J5, the specific gravity of 
common air being l. According to the -estimate tP 
Saus^QTc at the temperature of 72i , two Frmch oonce*' 
of ether, when convened into vapiiur, occupy Ihe spao" 
of about R French cubic footf If this eMifualc becw- 
TVCI, 100 cubic inches of eihenal vapour at that icai- 




rmture weigh only 45*15 grains troy, which woul4 ^^'^ 

ikc its specific gravity only 1*45* This estimate is 

eatly below that of Mr DaltoD, and in all probability 

low the truth. ^ 

£ther, when exposed to a cold of — 40^» fireezes and 

f stallizes f • 

3. Neither oxygen gas nor oogimon air produce aoj 

Eect upon ether in moderate temperatures; but in high 

oaperaturcs the case is very different. Ether is ex-» 

edingly inflammable^ and when kindled in the stale 

: vapour bums with rapidity^ with a fine white flame, 

id leaves behind it a trace of charcoal. During its 

imbustion carbonic acid is generated. How well so* 

rer it has been rectified^ it always exhibits traces of 

ilphuric acid %. 

When ether is admitted to any gaseous body stand* 
ig over mercury, it always doubles the bulk of the 
is^ as Dr Priestley first observed. If oxygen gas, 
tus expanded by ether, be presented to a lighted candle, 
m ether bums with great rapidity, but produces no 
cplosion. But if one part in bulk of this expanded 
cygen be mixed with three parts of pore oxygen gas, 
id kindled, a very loud explosion takes place : the 
x>ducts are water and 2^ parts of carbonic acid *• Mr 
ruikshanks, to whom we are indebted for this instruc* 
re experiment, ascertained, that one part of the vapour 

ether takes 6*8 parts of oxygen gas to consume it 
tmpletely ; and from the relative proportions of the 



t Fonrcvoy tncl Vaa^elin, Jw. dc Cbim, zxix. 189 

I Sdieele, iL 108. 

• CraiMiMiH NichoItoD*s /turmai, t. aoj. 



i 



CoMrODND C0tf8l'iTIIIt.tS. 

two products, he has shown th>l the csrbon which tAa 
conlninit ii lo it) hydrofivn u five to one. 

According to t>allon, one p«fi of rihcr by weigh: !» 
(juiics for itf combiistinn ^ parts of nxygen ; llifM 
ducti arc l^ parts of wntcr, and 3i of car^omctddt. 
Saus^ure junior has lately endeavoured to •scertita At 
ean&ttiuents of ether, by mixing a known qamtiiT if 
(thrriil vapaiif with oxygen gai, detomilhig the mir. 
lure, and csiimatinjt the proponion ofoxfj^en coo 
■nd of carbmiic acid {brnut. The following k ibc f> 
suit of his expei'imenit. Klher is ootnposctl of 

carbon gs*2 

hydrogen 22* 1 4 

oxygen 19*60 

lOO'OO II 

What renders rliia renult not lo be impliciily depend- 
td on is, tie pnibHbtl iiy that the ether of Sainiure, nhidl 
was of ihe specific gravity 0"T I -, still coitKiined 
tion of alcohol. We sec from it. however, thni luljiha- 
ric ether cotiiuiiis muth less oxygen Bud much 
mrbon and hydrogen than alcohol. 

Ingetihou&t wns the first who ascertained that the Vl^ 
pour of nhcr detonates with commun air and oxj|;a 
g«^. His acetinnt of ihe cxpeTimenl was first ptiblishtd 
in a letter to Dr Priestley, in one of the originsl to. 
lumcs of th»t ijhiIo«opher on Atr, and likewise in [he 
09th volume of the Philosophical TnnsactioDs. ffis 
Rieihod was exceedingly simple. A single drop of 









ITHER. 447 

iHher, let fall into a bottle holdinir aboot 1 cobic inches C^. TV* 
of air, gives it the property of detonating. Too much 
ether destroys the detonation. With oxygen gas the 
tenie method succeeds *• 

Wh^n ether in the st^te of vitpoiir is itiade to pafss 
through a red hot porcelain tube, it is deconftposed coft)«> 
pletely, and a great quantity of carbureted hydrogen 
gas is obtained f . Saiissu^e jnnit>r has lately repeated 
the experiment with precision. He passed 1103 parts 
of the ether through a red hot pdrcelain tube; the pro- 
ducts were as follows : 5^ parts of charcoal in the tube, 
3 parts of volatile oil crystallized in thin scales and 
smelling of benzoin ; 4S parts of a volatile oil neai4y 
black, partly fluid and partly of the cotisistenee of 1^ 
fiey ; 3 parts of water and Q49 patts 6f heavy inflam- 
mable air. The loss amounting to 100*15 parts was 
chiefly owing to the escape of oil in the stdie of va- 
pour J. 

4. Efhct does not combine witli water in any pro- 
portion i when the liquids ^re shaken together, they se- 
parate again ; but the water retains a portion of the 
«ther, v^hile the ether on the other hand remains unrited 
to a part oH the water. From the experiments of the 
Count de Lauragnais, vt learn that ten parts of water 
take Dp one of ether |. Alcohol, on the other hand, 
unites wiA ether in any ptoportion whatever. 



♦ Sec Tngrenbdun* FxpertfHcer^ p. t7i. 

f Dutch ChetnistA, Jour. *h Pl\t. xlv. 184. 

I Nicholson's Jovmal^ sii. ,';2). 

{ Mem, Pa-, tfjs^. From his ervrrim-iits it seems to fullow, that 
the portion taken np bv water is not other, but a substance which mny 
be obtained in cryitah by cTaporatioo. 



COMPHUKD COli80aTIBL£S. 

5. Of the Minple combuttiblea, ether scciuiu 
' only on pbos[>horu« and lulpbur. 

It is capable nfitisiolving a tmall proportion of pha 
phoTus. Tlic solu-.iuii is inniparent i but the a 
uf a iiule alcohol to it rctidcn it milky. Thit futniii 
u> with :l method of ascenainiog whciber ether be q 
phittiotrd with alcohol t> 

Ether wat luppoted incapable of acting on sotpbq 
except when both were in ibc slate of vapour, 
in(> to the expcriineiiu of Lauraguais i but Farre b 
kbowQ that a lolutioD ttiaj be obtained by di|n 
flowers of Eulplmi' in cold ether, and th^t the wlmE 
power of the ether is promoicd bj exposure lo tbtl 
light. By a croiilh'it digestion, he dti&olved nearly oi 
part of sulphur in 12 of sulphiiiic clhcr -, the >oIutiail 
was nearly colourless but had tlic taue and im^nfa 
Milphurttrd hydrogen +. 

G. Eihcr has no action on metals, but revives tbo 
thai hav« a weak affinity for oxygen when mixed wlit 
tlicir solution in acids, as gold and silver. It diuolrc 
the imiriuc of gold and the nxymuriaie of oicrcarjr. 

I* It is probable that it has no action tm fixed >Jkin 
lies snd earths; but it combines, or at lust mutein 
dily with ammonia. 

It absorbs nitrous gas in considcraBle quantity. 

3. Siilphupic acid sccmn capable of conves«ing tt ti 
a peculiar kind of oil known by the name of swcti o 
of wine. 

If wc fill a boltle capable of holding three or foDT J 



I DnigMicIli, ^H A CUa.t) 

i Orhko's/iBr. it. at;. 




b pints with oxymuriatic acid ^^ taking uretb 
• water as completely as posiible, and then 
tlirow into it about a dram, or half a dram, of good 
' ether, covering its moi;th immediately with a piece of 
light wood or paper, in a few seconds white vapour vrill 
tw perceired moving circular in the bottle : this will 
be soon followed by an explosion accompanied «ith 
flame ; at the same lime a very considerable quantity of 
diKTCoal will be deposited, and the bottle will be found 
U) contain carbonic acid gas *. The action of the 
other acids upon ether has not been examined with at* 
tenlton. 

9. Ether dissolves the fixed and volatile oils, faitu- 
inens, those at least which are fluid, and resins ; bat it 
does not act upon gumf. 

10. Chemists entertained vanous opinions respecting 1 
the nature of ether. Macquer supposed that it was \ 
nterely alcohol deprived by the acid of all its water. 
But it was generally believed that the acid entered part- 
ly into its composition. Scheele published a set of ex- 
periments on ether in nS2 J ; from which he drew as 

a consequence, that during the process the alcohol is de- 
prived of phlogiston. These experiments were varied, 
and tarried still farther by Pelletier ; who adopted the 
theory of Scheele, modified according to the disco vC' 
rics of Lavoisier. According to him, ether is alcohol 
combtned with oxygen. This theory was embraced by 
tlie greater number of chemistSj and it was supposed 
tfaattbe alcohol obtained the new dose of oxygen from 



P 



* Crnikihuiki, NithoUoi.'i Jiir. «. soj. 

f MimutdtCiymii by iti- Dijon Ataritmy, iii. p.3l^ 

t Schctlr, i!. toj. 

PW. II. V f 



COMrOUHS CaMBUSTTBLES. 

(he sulphuric acid. Rut tl)e formxiton of dW 
been litcly examined with much rare hy Fuurcru) 
Vtinqucliu. These ingenious chemtsis liavc cmdi 
from tlieir esperimcnii, thai during the- prnceuthe 
bal is completely decomposed, iind tliai citiet is 
posed of ihe tame ingedients » alcohol, but com 
in differciil proportions. Kiher, according to tU% 
contains a greater proportion of hydrogen and oijip^ 
aod a smaller proportion of cu-boo ibaii alcohol *. 
Th< ihcory (if these chemists was disputed b; ] 
detf and DHbit t. who endeavaured to prove thai < 
gen is always necessary for the fortnation of cih«> 
This they did by repenting ihe experimenta on eihs 
which had been forirerly made by Scherle. They liik 
tilled a mixiuie of sulphuric acid, black, oxide of 
ganese, and alcohol. The sulphuric acid was not <1^ 
composed, as in common casts, no charcoal ivas dcpoii. 
ted, no gas came over, the black oxide lost pai 
oxygen, and the quatitity of tlifr obtained tvaa gnua 
than usual. Accord inj; to Dabit, cihcr contain* a siii>l> 
Icr proportion of hydrogen, and a grcaler proporlioo of ' 
oxygen aitd carbon, than «lcoliol. These cbjcc 
were almost immediaiely answered by Fourcroy 
VauqueJin, who proved that ether obtained by m 
of (he black oxide of manganese possesses very diffcr> 
cnt properties from sulphuric ether. Coii»e4]ueiil]y tit 
formation and composition cannot destroy titcir coiKia> 
aioni respecting the formation ard composition < inL 
phuric ether f . From the preceding nnalysxi of Sun* 



t Ibid. uiiT. )()■ 



Hire it fol]6wSy that ether coutaii<$ less oxjgen that! kU ^Q«p » IV. 

' teholy hut more carbon and hydrogen* 

ll4 As the action of sulphuric acid on alcohoL and Af^K»5>f 

. . •aiphttnc »• 

' the formation of ctberi is one of the most interesting cid on ako* 
' phenomena in chemistry^ and as it may enable us to 
fiorm more precise ideas, both respecting the composi- 
tion of alcohol and ether, it will be proper to ejuunine 
it with attention. 

. When four parts of sulphuric aoid and ooe part of i . Okfiaoi 
mlcohol are mixed together, and a moderate heat ap. ^^ 
plied, the mixture blackens, boils violently^ and a great 
quantity of gas is disengaged. This gas^ which was first 
examined by the Dutch chemists, received from them 
the narne ot olefiant gas* It has been described in a 
former part of *this Work> under the name of sufer^ 
carbureted hydrogen *• 

What remains in the retort after the disengagement 
of this gas is chiefly sulphurous acid blackened with 
diarcoal, and probably also some vegetable acid* 

When equal parts of sulphuric acid and alcohol are s. OuQa 
nixed together, the phenomena which take place are 
considerably different* If the mixture be made cau* 
tioosly, and allowed to remain at the common tem- 
perature for about 30 hours, crystals of oxalic acid often 
form in it f * 

A combination of two parts of sulphuric acid and one 
of «lco&>I elevates the temperature to 20 1^^ become* 
imaiediatelj of a deep red colour, which changes to a 
Uodt s fiew daya afterwards, and emiu a smell percep« 
liUj othereaL 



• See V«L I. p. jlS. f Cadet, /#«r. d* Pbyt. IL 13!. 



rw> 



COMFOUKD COMIDSTIILES. 

When > mixture of equal pans of alcohol ud 
i phutic acid is exposed to the actioa of lieat in a 
ajiparatus, the following phetiomena take [4Ke, 
been atcertaincd by Fourcroy and VautjucHn. 

When the temperature is elevated to 208", lie 
boils, and emits a. vapour whicli becomes co 
cold into a colourless, light, and odorani liquor, «1 
from its progenies has received the name of ttkt. 
the openiiou be properly conducted, no pcrmaneai 
is diiengaged until about half the alcohol has 
ever in the form of eiher. Until this period there pih 
MS absolutely noihing but ether and a bmall portion ll 
water, without mixture of sulphurous or of carbedt 
acid. 

If the receiver be chan|;ed as soon as the sulpbona 
acid mamfciis itself, ii is observed that ito na 
is formed, but the svrcci oil of wine, water, and 
acid, without (he diiengagcmeat hitherto of a vo^ 
bubble of carbonic acid gas. When ibe solphuric ad 
constitutes about four-iifihs of the mass which rcintii 
in the reion, an inflammable gas it disengaged, wbid 
has the smell of ether, and burns tvtth a while t^ 
flame. This is ivhat ihe Dutch chemists have ealli 
tItfiMU gal. At this period the lemperainre of l| 
fluid couiamed in the retort is clevaied to 2S0* rf 

as*' 

- Wlien the sweet oil of wine ceases to flow, if the fV 
ceJTcr bo again changed, ii is found that nothrug noa 
paiscs but sulphurous acid, watett carbonic acid gaj 
and that the residuum in llie letori isa bl«ck masi^cMj 
sistiug fur the most part of sulphuric acid tiuckened bj 
carbon. 



, From these phenomena Fourcroj* tad Vauqaelin C*»p. tv. 
i drawn the following deductions. 

A small quantity of eiher i» formed spontaneoiislj, ?"?^ "^ 
Imd witfiout the assistanoe of heat, by the CDmbiDition p<w'iaii of 
Bf two partt of conceamted sulphuric mcid and one put ttiphari/ 
«f»lcohol. ""^ 

As soon as ether is formed, there is a production of 
WVtET at the same time i and while the first of these 
fiomposilions takes place, the sulphuric acid undergoes 
no change in its intimate nature. 

As soon as the sulphurous acid appears, no more 
etber is formed, or at least very little i but the sweet 
oil of wine passes over, together with water and acetic 
acid. 

The sweet oil of wine having ceased to come over, 
nothing further is obtained but the sulphurous and car- 
bonic acids, and at last sulphur, if the distillation be 
carried to dryness. 

The operation of ether is therefore naturally divided 
iato three periods : the first, in which a small quantity 
of ether and water are formed without the assistance of 
heal ; the second, in which the whole of the ether which 
cm be obtained is disengaged without the accompani- 
ment of sulphurous acid ; and the third, in which the 
sweet oil of wine, the acetous acid, the sulphurous acid, 
aad the- carbonic acid, are afforded. The three stages 
have no circumstance common to all but the coniinuil 
formation of water, which takes place during the whole 
of the operaiion. 

A combination of sulphuric acid and alcohol in equal 
parta does not boil at less than COT* of tCDFcraturc, 
wfail« that of alcohol alone boils al ne". Now itoce 
^ollitioa don not tdce place till the higher Irmperaturc, 



454 eOMfOUKD OOMBUSTIBLSS. « 

^mo\ lU ^t 18 clear ifiat the alcohol i» retained by the aflfeh? of 
the sulphuric acid, which fixes it more considcraUj, 
Now organic bodies^ or their itnmrdiate products, wbea 
exposed to a liFely brisk hear, without the possiluliYj 
of escaping speedily enough from its action, suffer i 
partial or total decomposition, according to the degrte 
o{ temperature. Alcohol tindtrrgoes this last alteratiori 
vfhen passed through an ignited tube of porceliiE. 
The reason therefore why alcohol is not decomposed 
W'hen it is submitted alone to heat in the ordinary ap. 
paratus for distillation is, that the temperature at whidi 
it rises in vapours is not capable of affecting the scpan. 
tion of its principles ; but when it is fixed by the sul* 
phuric acid or any other body, the elevated tcmpentore 
it undergoes, without the possibility of disengagement 
from its combination, is sufHcient to bfTect a commence^ 
ment of decomposition, in which ether and water are 
formed, and carbon is deposited. Nothing more there* 
fore happens to the alcohol in these circumstances 
than what takes place in the distillation of every other 
vegetable matter, in which water, oil, acid, and cortI,are 
afforded. 

Hence it may be conceived that the nature of tic 
products of the decomposition of alcohol must vary ac* 
jcording to the different degrees of heat ; and this ex- 
plains why at a certain period no more ether is formed 
but the sweet oil of wine and acetous acid. In fact^ 
when the greatest quantity of alcohol has been changed 
into ether, the mixture becomes more dense, sod 
the beat which it acquires previous to ebullition is 
IDore ooQiiderable. Tlie affinity of the acid for alcobol 
b^bg tncreaaed, the principles of this acid become kp 
fNIMll mt^ 90 tl»» we baiid, iu ox^gea seizes tin 



ETHER. 4S6 

hydrogen, and forms much water, which is gradually vo- Chap. IV. 
latilized ; while, on the other, the ether reiauting a 
^eater quantity of carbon, with which at that tempera- 
ture it can rise, affords the sweet oil of wine. This 
Inst ought therefore to be considered as an ether con* 
taining an extraordinary portion ot carbon, which gives 
it more density, less volatility, and a lemon- yellow "co- 
lou.'. 

Such is the ingenious explanation of the formation of 
sulphuric ether proposed by Fourcroy and Vauqueiin. 
They have succeeded completely in proving that the 
opinions formerly entertained respecting that singular 
process were erroneous; though their own explanation 
is i.ot sufficient!} precise to enable us lo ascertain exact* 
I J the component parts of ether. 

II. Nitric Ethek. 

Nitric ether is first mentioned in an epistle written 
by Kunkel to Voight, and published in 1081 *; but no 
attention was paid to it by succeeding chemists till it 
vrab discovered a second time by Navier in 1742 f, and 
a third time by Sebastlani in 1746 (• 

The method of preparing it, proposed by Navier, Prepan- 
vas this ;. Twelve parts of alcohol are put into a strong 
bottle, which is kept surroimded with water, or rather 
with ice : eight parts of nitric acid are poured in at 
intervals, the mixture being agitated after tvtry addi- 
don. The bottle is then well corked, and the cork se« 



• Bfiddm ttiOwm Spiwkwm J'MnsfejUUb. 

f Mm. FjT. I74t« t ^>W'« ^^ ^'ro, 1 746* 




"PPfia,o,i 











gueoui toriD, while Ibe liquid lo 
to coostdered nitric eitier, ww s 
waUr, ether, nitroos, wid ueiic m 
kd him to the followiag methw 
nitric ether. 

Equal weight) of alcohol and ni 
ciGc graviif 1>883, were put intc 
beak o( the retort waa luted a glai 
ged to the bottom of a loog narrow 
with a latnrated lolutian of con 
From the lop of this jar paned i 
went to the bottom of another aini 
filled with t lolution of common ti 
five similar jan were connected w 
half filled with a aaturated toluli 
From the lait a tnbe paised to a 
ceivc the gaaeoai products in pro 
tfiete five jara was surrounded witi 
■nd salt 10 keep it as cool ai posi 
heal being applied to the retort m \ 
began. It waa found neceasary ti 
and even to moisten the outside of tl 
in order to prevent the vessels fir 



F 



ityt Bjr this method, knowing the specific gttvity of 
the vapour, and ihc products furDished by its deconipo* 
Btifin, ii would have been easy to have deduced its con- 



Suring the formation of nitric ether a vast quantity 
of gas is evolved. The Dutch chemists examined this 
gas, and considered it as a compound of nitrous gas and 
nfacT i but Thenard has shown, that it is much more 
complicated in its nature. The result of his examina. 
Uon is, that it consists chiefly of nitrous oxide gas, 
mixed with a little nitrous gas, azote, carbonic acidi 
•cede acid, nitrous acid, and a considerablet proportion 
of etherial vapour. But the proportion of this last in- 
gredient diminishes according to the degree of cold to 
whicli it has been subjected. 

After the mixture of alcohol and nitric acid has 
ceased to give out ether, there remains in the retort 
Aaut three-fifths of the original quantity. This residue 
Thenard also subjected to examioation. It has a yel- 
low colour and an acid taste. It consists chiefly of 
water, holding in solution some nitric acid, some alco- 
hol, a very small portion of acetic acid, and a matter 
which Thenard could not separate, but which very 
readily assumed the state of charcoal. 

Thus it appears, that both the alcohol and acid are 
decomposed during the process of making niiric eiher, 
and that the constituents of both enter into the ccmpo- 
tition of the cilicr formed. We are not sul!ipientlj' ac- 
qnaioled with the composition of alcohol, and with the 
proporticn of the other ingredients evolved, lo he able 
to enter into the minutix of the dci 




it may bc<jbrowa upon the subject by a careful ex- 



I 



CtlKTomD COHHVSTrSLR. 

•raiaftltea of ihc phenomena which taJu plicc iiM 
the aciion of niitk add cm alcohol. 

1. Wlien «]iul pani of alcohol and nitric malm 
mixed, a vioUni ctTctvcHicncc takes plicc ; i| 
oMs]j if ihe acid be (.mi cent rated ; on the appbi 
heat if the acid be diluted. This efTefvevceocc i 
10 ihe emiviion of the gat, which the Dutch i 
considered as a mixlute of ether and oitroua gtt, k| 
which Tbeoaid has thown to conaist chicSy ol 
oxide and ether. The Dutch chemisU have nQtd 
nilrous ethenz.til gas *. 

Ttiii gaslliii. a<liM){recable ethereal odour: tl 
with a ycUow flame; is completely abM>rbed br 
alcohol, and the lulution of potash i ammooia hu 
action un it. Wlicn fiicd nlonfj with oxjgen gaaiti 
lonitet. Suljiliuric, luJpbuTous, nitric, and tnani 
acidi, decompose it. 

2. When one part of alcohol and three parttofnii 
acid, of the specific gravity rzGI, am miaicd 
and a very moderate heat applied, a great qiuntiiyi 
g»s isdisengaged, which consists chiefly of niironseil 
ri»cd gas and nitrous gas. When o(iIy ,\d partof 
liquid remains in the retort, if it be allowed to cm), 
Dumhcr of crystals of oxalic acid are farmed f . By lU 
process l-ia~ parts of oxalic acid may be obfajoed iroa 
16 parts of alcohol t- 

3. When one part of nitric acid is poured Upon 
own weight of alcohol, and one part of sulphuric .-i 
it added a little after, the mixture takes lire and biu 






^reat rapiditj. When this experiment is pet- Clup.ir. 

td in close vesicls, ihr products are ether and oil, ^3Sl 

'^elides what remains in the vessel in whicb the com- ^^H 

"bisiion takci place *. ^^H 

4. When nitric acid, partly saturated with mercury, HnwntW 
n poured upon alcohol, and heat applied, the products fulmmujni 
are nearly the same, but the phenomena are very diffe- 
ivnt. The curious appearances which accompaay this 
Snixlure were first observed and esplsined by Mr 
Howard f. The process, as described by him, is as 
AlUows: Dissolve, by means of heal, 100 grains of 
■SDercury in a measured ounce and a half of nitric acid, 
«f ilie specific gravity of about 1-3. Pour this solution 
upon two measured ounces of alcohol, and apply heal 
rill the mixture begins lo effervesce. Tlie heat is thca 
to be withdrawn. The action becomes violent, andcon- 
tioues for some time ; a dense white smoke issues front 
ihe vessel, which is heavier than the atmospheric air, 
and may be poured into glass jars, where it continues 
for some time like fine white clouds, Mr Howard has 
made it probable that ihis fume is composed of cthe- 
nstd nitrous gas holding oxide of mercury in solution. 
Meanwhile a white powder falU lo the bottom of the 
mixture. When the efTerveicence is over, this white 
powder is lo be separated by filtration, washed with 
pure water, and dried in a heat not exceeding 212°. 

Mr Howard has examined the properties of this pow- 
der, which hw the appearance of minute crystals. He 
has given it the name of fulminating mercury. 



I 



n.itChSm.TiM 

bf Nicholiuo'>/«'*df, i<r.t7j. 



£ther« 463 

■ti mercury, and more of the peculiar vegetable iiiattier« ^Chap. I v« 
^, When the mixture is boiled for half an hour, the pow- 
der is composed of oxalate of mercury and a very small 
_ quantity of vegetable matter. It does not detonate, but 
«L decrepitates when heated*. These experiments of Four- 
5 croy enable us to reconcile the seemingly opposite rc- 
. sulu of Howard and Benhollet f . 



in. Muriatic £th£R. 

After the discovery of sulphuric and nittic ethers^ 
various attempts were made to obtain ether by the ac« 
Uon of muriatic acid on alcohol : But this acid in its 
usual state is too much diluted with water to act with 
much energy upon alcohol. It was thought necessary^ 
therefore^ in order to procure muriatic ether, to employ 
the acid in a different state. Two methods have been 
discovered. 

1. Those muriatic salts are chosen which may be ob- e^epm. 
tained dry, and at the same time have a strong affinity '***"• 
for water. All the salts which have been hitherto tried i. By alu} 
vrith success have a metallic base in the state of a per- 
oxide {• The ox jr muriates of mercury, iron^ arsenic, 
and antimony, produce ether when distilled with alco- 
hol : but the salt which answers best is the ozymuriate 



^ Jotirmat •/ tk* Koyat Imttit. i. 156. 

4 According to Bcrthollet, fulminating mercury is composed i^f am* 
monu, oxide c^ mercury, and altered alcohol, which produces carhonie 
acid when decomposed. Pbit. M«/. >iL 9s. 

X IdittingiMih this state of ozidizement in the metallic salts by pre- 
Aying •my to the ttioal names of the salt. 

Vcl. It. o g 



m 



courotrvo coHaosniut. 

^ of t!n. Bjr BUMS of this sail 
/ cthtr, in 1 15P. bjr (he following 

of fuming ozvrauriate of lin and one puti 
mixed togcttit^r ; and after the vapoun 
Cerf have siibsiilcd, the mixiure i> put 
which two large receivers are attached, uj 
There comes over first a Utile nlcoHot, ibn itiettfj 
This salt has b*en lately recommcndtd mtoj 
for making muriatir ellier by Klaprothi-. 

3. Pure alcohol i^ naiuraied with mutiaticioi' 
free from witter as jjoisifale. Th« following is *•■ 
Rtula rccommeiidcd by Mr Basse. Keep a ^< 
common salt for an hour in a state of fntBOO, ^ 
lo d«prire tt of its water of cry itallizaUsn. 
piTU of this salt into a tubulated retort, to the 
which is fitted a bent tube, plunging into Wo«I£i 
lie, ooniiiniDg 10 parts of alcohol as stroDgga 

Introduce into the retort, in small ijuantitiea M 
10 parts of the roost concentrated sulphnnc a 
losriog the common air to escape from the boll 
laitiinA the alcohol ; then distil in a saxid bath 
moriaiic acid comes over, keeping the alcohol 
c«e) ai possible during the process. The alcoh 
samratad with acid, is put into a retort, and ooe 
it disiiUtd over. Agitate this portioD with an i 
IcT, and then decant off the ether which ! 
•vrtacc : it (UBallv amouots to 2^ parU t- 



ThH grmtm mm Jimmwt ^ 






ETHER. 



467 



e was known of the properties of muriatic Chap, iv.^ 
titlGehlen published a dissertation on the sub- 
t 1804*. He employed two processes: 1. the 
«if the fuming oxjmuriate of tin oa alcohol t 2. 
i0ceis of Basse detailed above. Both of them fur- 
1. mnriatic ether, the peculiar propertiea of which 
^S described wiih accuracy. Theaard published 

«flisserlBtions on it in 1801 f, pointed out the siro- 

process for obtaining it, examined the eSect of ozy- 

l.tes on alcohol, described the properties of mun- 

tfier in detail, and m^e a set of experimeats to 

ain its constitucnis. To the dissertations of tboe 

bemists we are indebted for all that we know of 

cry remarkable substance. 

e process recommended by Tlienard for procuring ThenirtlH 

ther is the following; £,qual bulks of muriatic scid 

Boholf bothasstrongas possible, arc put into aretort, 

H a siic as not much more than lo hold the mixture. 

I grainsof sand should be put into the report, to pre - 

bcviolentboilingwhich might otherwisetake place. 

the beak of the retort a tube pass<^s into a glais 
Kioe the size of the retort, and furnished with three < 
k«. This jar should be half tilled with water, of 1 
mperature of about lo". Into the second mouth I 



proMu. 



i, kf dinillingi Rilitare of two pint of camrnon 

pan of n)phuric acid oitii « Wiiulfc't •ppuaiui containing two * 

alcshoL Mil ihii ■stunted alcohol with hilf i part of btack 

manganrw, uid put into ihe Woulfc't appualut i tolution of 

UMb in water, and dinil wilh a iow heat. Tho edwr and oif. 






, 3cc^-.rffa«.l 






the aeid from ai 
T. 1*1. 



t ,Vfm.rf"^r.«i/,i. 



COMFOCS'D COMBUST 

of (in. By menus of this sal 
' ether, in 1750, by the follow 
of fuming oz^ munate of tin 
mixed togtthcr ; and ifter 
ced liavt snbsiiJed, the i- 
which two UrRe receiv 
There comei over firs' 
Thi'i salt has been la'' 
for making muriati'' 

2. Pure alcohol 
free from water ^ 
miila rtcommpi' 
common lall (■ 
to deprive it 
parW of this 

which isfiri" •' 

lie, containi- .■■■ivkhi 

Introdti 
JO parti • 
lowing tl" 
tainiric tn- 
muriaiji^- 
cool a- •" 
■alurWP*" 
it riittik*' 
kj , — 
tur.'a 



I- being I. 
a ovni WU 



■•••■■M of 52*. it lem i 

< i'Ljiiid ether. It may be] 

^ ;i state by paising ii into a dry 

>':h ice. Muriatic ether, in itaKqi 

.-. ::ke waur. vtrj li^aid, has no a 

: ::tin, tad hsf the iBine nneU and ti 

.wsiaie. At the temperature of 41*. 

ol the qwdfic grarit^ 0*874*. It 

dun alcohol, or crrn aulphoric e 

tate vhen not liollcr tb 



il of ihr iprcilic gravity 0810, ani) CdS 
-eisht «i a mart of j-uriiy. Heme t 



^«« • 409 

the presence of any Cha p, iv. 
^vetabk blues, nor 
'ine ley, or oc- 
^d wiih ni* 
' with a 
•ired 
acid 
. This 
Gehlen : 
.id. When 
)ntact with an 
.uriatic acid, and 
urate of silver after 
ilie quantity of preci- 
Bat in neither case is 
prived of the property of 
N iien burnt. 
.'.s of Thenard it appears, that Composi- 
. ot muriatic ether no gaseous pro- 
. jived but muriatic ether ; nor is any 
:icc evolved, unless a portion of water 
J. A portion of the muriatic acid as 
! ritr alcohol disappears ; and when the ether 
:. posed, exactly the portion of acid is evolved 
liad disappeared. It is extremely difficult from 
c facts to form an accurate notion of the way in 
w hich the ctfaer is formed. Is it a compound of alco- 
hol and muriatic acid ?<— The little effect which these 
two bodies bave on each other, even when mixed in 
the state of vapour, renders ifaat opinion unlikely. It 
is cqDsJly difficult to conceive the state of the muriatic 
ecid in that liquid. It seems to be perfectly neutraK- 
Mdy ai sUits fisiial properties are concealed i and it must 



u il 



■r>\ 



COMFOUND COHinTtXLES. 

be retiuned very powerfully, i'lacc oooe of tbowabi 
■ <uncei oa which it acts with the greatest eongy 
c»e its prrscncc when mixed wiib tbc ether. At At 
mne time, difficult as it is to explain how it ii 
ed, it is more probable that it exists in the stale ofan* 
riaiic add than decomposed, if wc consider how S& 
cah it is to decompose this acid, and how obstinaidj 
hat resisted the numerous attempts to ascenainitte 
position. 

Tbenard has endeavoured (o ascertain the cdid| 
tion of oinriatic ether. From the quantity ofnwr 
acid which disappears during its formation, be has 
culaled that 1 00 parts of mumcic ether contain S9*44 1 
Kcidi sneoonnout qoantity, sinceit exceeds the 
tion of real acid in the strongest muriatio acid of c 
nerce. By mixing deteiminate portions of muriatic 
gas with oxygen gas, firing the mixture, and ascemii 
the prodncti, which are only carbonic acid and wster, 
cndeavouced to ascertain the proportion of the oil 
constituents. Ttic following is the result of hisexai 
natioD : 20*44 muriatic acid 

36-61 carbon 

23*31 oxygen 

10-64 hydrogen 

JOO-00* 
If any confidcDce can be put in this analysis and 
Ast of alcohol by Saussure, we may infer from the 
that murisiic ether does not contain the alcohol ini 
c of alcohol, since the carbon, oxygen, and hjinpm 
» bear to each odier the same proporlioo in tlie c* 



" Mbm. O'Jratit, L 341, 



^obaU 



Ihejr do in alcohol. The proportion of car- ^^'P- 
: ether is a good deal more, and that of the ox- 
less than in the alcohol. 
After ihe discovery of oijmuriatic atld, Scheeic 
•bowed that eiher might be obtained by ditliUing a 
tnbclurc of alcohol, black oxide of manganese, and mt]> 
natic acid ; or by distilling sulphuric acid, common salt, 
Uack oxide of manganese, and alcohul : but the quan- 
tity which can be obtained by this process is trifling; 
tot the oxymuriaiie acid acts upon the ether formed, 
and converts it into a kind of oil. Indeed, if we believe 
Mr Basse, ether is never obtained by means of oxvmu- 
riatic acid, but merely an oil which sinks in water*. 
This has been amply confirmed by the tale experiments 
of Thenard+ ; Irom which we may conclude, ihatoxy- 
muriaiic acid converts alcohol into oil, and not into ether, 
and that which has been taken for ether is noiliing else 
thsti alcohol holding some of this oil in solution. 
IV. Aci^TlC Etber. 

Ether may be produced also by the action of acetic 
acid on alcohol. This was discovered by the Count de 
Laaraguais in 1159 t- He obtained it by distilling a 
mixture of acetic acid and alcohol with the same pre- 
cautions as are employed in the distillation of sulphuric 
ether. 

The process, as corrected by PcUelier, is as follows : PMpir*. 
Mix together, in a retort, equal quantities of acetic **• 
acid (from acetate of copper) and alcohol, and distil 
OKT the alcohol. Pour it back into the retort, and di- 



_• /nr.JrCiim.il.SZ. 



aim. li'AmiU. i. 47. 




ty a. violent boitiDgi the pboipborU Chip . IT. ^ 
ack, and stria in abundance appeared on ' Jj 

cit of the retort. The diKlillation was 
he phosphoric acid became dry. There 

the receiver, Ist, 1 20 pans of alcohol, I 
ofeiher; 2d,260partsofa colourlcs&light | 

r strong of ether j 3d, 60 parts ofwalersa^ || 

licr, over which swam 4 pans of a yellow 1 

ch resembling ihe iwett oil ftfu-ine in ap. 
, another liquid of a disagreeable odour, 
vegetable blues. When saturated with i 

iporaied, it left a quantity of acetate of D 

als. The lime waier became milky, but ! 

Ite end of the process. A-quaniily of gas 
rbtch burnt like elher, and seemed to con- 
cthei uncondensed. 

II products being reclined on muriate of Fropstic*. 
60 parts of a liquor bearing the closest 

1 sulphuric ether. Il had the same smell 
ime specific gra»ity, dissolved in 8 or 10 
rater, boiled at ihe temperature of lOO", 
IS and phosphorus, barnt with a white 
t trace of charcoal, but giving no indica- 
wnce of any acid. 
[>esu^ that phosphoric ether approaches 

sulphuric ether, if it be not absolutely 
it, and differs very considerably from ni- 
and acetic ethers. 

be formed also by several other acids, 
ed it by distilling a mixture of fluor spar, 
' manganese, alcohol, and sulphuric acid ; 
by means of oxalic acid. Scbeek found 



476 COUfOZSn COMBVSTnitL 



Bwkn. thit the followi::' acids did not former!? 
hol*. 

1. Mjrrr.-c, 4. Benzoic, 

2. Fiucric, 5. Tartaric, 

3. B?r2c:c, e. Citric, 
Thus it appears that there are varioai 

thers difiVrin;; rerr much from each other n 
pertics. Sulphuric ether is the lightesbs! 
▼oUtile of the whole. la muriatic and acttic 4 
acid seems to enter as a constituent part, butitspRf 
are concealed altogether while the liquid mnn 
composed. It is not unlikely that nitric ether 1 
to contain an acid. It is obvious that the theofj 
formation of nitric, muriatic, and acetic ethcni 
quite different from that of sulphuric and phoipb 
thers. The theory of the two last is probabljs 



SECT. III. 



OF VOLATILE OILS, 



X HE term oil is applied to a number of unctt 
quids, which, when dropt upon paper, sink inti 
make it seem semitransparen:, or give it what i 
a greasy stain. These bodies are very numen 
have been in common use from time immemoria 
mists have divided them into two classes ; nami 
/a*ik wadjixidoilt. We shall consider the propi 

•Scheele,iU n;. 



VotATTtS OILS. 



Bk«se classes in this Section. The/Woils Oi^ 

Spy our atleniion in the next. A third class 

lighlbe added which possess intermcdiaie pro- 

Miween the fixed nnd [be volatile. 

LTILE OILS, called also eiieniial oilt, are distin> 

bv the following properties : 

quid^ often almost as liquid as water; some- chmctokl 

(cid. 

cry combustible. 

n acrid taste and a strong fragrant odour. 

olatilized at a temperature not higher than 

iluble in alcohol, and imperfectly in water, 
vaporatc without leaving any (tain on paper, 
tis last test it i» easy to discover whether they 
eti adulterated with any of the fined oils. Let 
of the volatile oil fail upon a sheet of writing 
uid then apply a gentle hem to it. If it evapo- 
ihoul leaving any Main upon the paper, the oil 
i but if it leaves a stain, it has been coDtamina- 
1 some fixed oil or other. 

tile oils are almost all obtained from vegetables, » 
f exist in every part of plants ; the root, the t*"". 
M wood, the leaves, the flower, and even the 
lOUg'h ihey are never found in the subblance of 
rledons ; whereas the fixed oils, on the contrary, 
ost always contained in thee bodies*, 
n the volatile oiU are cotiliined in great abun- 
l plants, ihey arc sometimes obtained by simple 
ton. This is the case with the oil of oranges. 



'^^ 



." -. .J»l- l.UitJlI«9TtBi.L 






fl%»^ 1.4. 



.'•.<^J.>.. • 



«.%Ma.«h<Mi»*. i^ . V. .. •■'U'. ilK-' 1^ &till I^jI.. aQMB 

■•«.«. •».. . i. ;A^r. ..«c. o!: uv inc MppiiMuaiit.i 

Ww««k-. .ACr. I «j'. v.. wULli*: --UVrl iUUlll.' WlU! *tKl 

y../*i.0 «••. i>jbr..jfr^ i«i'. u.. (.1 pCfHicriur. .. 

Vs..«Uc «•'. • \.«:f. ilib:;- Cliiri . UiJt.ititir 
^.. ,4«i;«CJt«' t«.'. Ui U. LU'p^Ulll!*. . IK nil.: lA 

t^L^.. «o.<^ r.:.-«/%»i. f uu: i>^ Uk;i: iib«r lit CUmUSlTT BE! 

j . i >'( ^ I « . .1 f liUtliOt.J U \L';c;l!l'. I'li. ail 420 
it.,.\.j ...•.»«' ..t . ■ IiijjiC. i:: V' <r.'.*c' . a'nU Liii'^ '.' liDlS 

i #. : *:: li.' '.isM: V% ; lii (M I'JiiUViilJi . UHIUtTi^. O: 

i.uvi: iJii i^jl^ vj^iflity. J; v<;^ieb II. tntru. :t- sJ; 
«j.i^ifi^ £.is.«l«a&^ • ii^vid^ ciiiiiS&iAiUii. Oliitrii iiavt 

tijjft ut^ {iiAlbky, lilliAC-l^ iilllbCrdp \jAw. O'M^Vt Tyi 

U/.C by kluw LVtf|i<inilioii. 'lliiai :% \ht i^.hc uiii. i./. 



veLATItE OILS. 

le consistence of butter •. This ii the 
with the oil of hops and of pepper. 
Hie colour of the volatile oils is as variou* u i 
filer properties. A great number are limpid 
iirless, as oils of turpentine, lavender, rosemtrjr, 
[ aniseed. Some are yellow, as spike, ber^ 
Some are brown, as thyme, savonjr, worm- 
I Others blue, as camomije, motherwort. Others 
w milfoil, pepper, hops, parsley, wormwood, 
|mt( juniper, sage, valerian. Others, though at 
colonrless, become yellow or brown by age, as 
es, cinnamon, sassafras t. 
, Their odours are so various as to defy all des- i 
lion, II is sufficient to say, that all the fragrance 
y vegetable kingdom resides in the volatile oils, 
bste ia dlways acrid, hot, and exceedingly un- 



r specific gravity varies very considerably, i 
f in different oils, but even in the same oil in dif- ' 
F^trcumstaTices. The following are the specific 
Sties of several of the volatile oih, as ascertained by 
Lewis t. 



if sassafras.. 1-004 Oil of Mint., 



Cmnamon 1'035 



■975 



Nu 



megs . . . 



Din,.,...-9>J4 
Kimy royal '91S 



Carraway s< 
Origanum . 
Spike .... 
Rosemary . 



t Nnutua'i C/ur. F- S7t. 



COMFOUtfS COMBVSriBU 

OQtffjQtiiprrberrin 'fill Oil of TarpaiH^ 
* Orugca..,.,,-88B i 

Wben the voUule oil* are heated in Af ij 
ther cvapoTM* nnulitr, and wiihont altniBa^ 
ibcir pcculiai odoun all aiotind ] but thnriii 
derabladtScrc-nccbetivcrn the diftercot oi1ib( 
peeC WHea diftilied in close vaxlt, t^ ii 
rnidily amucoe the furm of vapour. Htuct i 
their odour, become darker in coloar, ni m 
decoinpD^. Oil* do not seem ver^ intcepriBi 
Ruming the gaseous foim, uoless lome Mbernl 
- _t» water, be pretent. 

OM. iWhcn exposed to tbe action of cold, thejea^ 
,. tft«4x<doilsi bai the umperaiuto neccenjtiii 
'ilhUeficct variekKcotdiog to the oil. Sonc(f 
a» oil of anise and of femtel, become tolid it d| 
- 1 frratuc of M* : fitexeo oil of bergamotte ud tf i 
,bMOttie liquid at 33' ; oil of turpentine at 14**. 
Xueron expowd several *olstiIe oils lo ■ ccUof- 
ITjey concealed or rather a-jrsullizcd paniiQ;,! 
Ihe same line emitted >o claitic fluid. Tbex^ 
consisted patllj: of the oils themselves, pmlfd 
aubtiances. Some of them had the [rropertteiof 
toic add f.' 

d. Volatile eils, whenexpoKdtotheacM»«(E 
dose veuelt, and excluded from common tk,u 
verj singular changes. Their colour bccotnoA 
they acquire a great deal of const srencj', and ihfll 
cific gravity ia conaidcrably increased. The ta 




a Mtfxncnni, /nr. A fty. xU. t j6. 



I 



* TOLJITILE OILS. 

* _, 
Onanget is but impcrfecily known. Tingry, to Wup. IV. 

■i we nre indebted far these imeresting researches, 

a^ved tliat lli^ht is a necessary agent. It was sup> 

■i formerly tlial they weie occaiiioned by the ab- 

(fco of oxygen ; and when oxygen is present, it 

IH^a ascertained that it is absorbed : bat Tingry 

l^ovcd lliat the mme changes go on when oxygen 

eluded. This philosopher ascribes them lo ih« ] 

enoDight. If this be die real cause, the qiiantiij' 1 

jilt fixed mtisl be enormous; for as the specific 

17 of the oils is increased considerably while ibe 

cvniinues ihe same, il is evident that the absoIulA ' 

jl must be increased proportionably. One cir- 

[sncc, however, rendtrs this conclusion somewhat 

fill, at least in its full extent ; and that is, that the 

iVf of change was always proportional to thfe 

i(y of the oil and the quantity of air coolained in 

»a«l*. 

HTfatn volatile oils are exposed to the open atr, ibey Abtorb 

jlly become deeper coloured, and acquire more '"i'P"' 

ore viscidity, while at ilie same time their odour 

sites. Dr Priestley fiist ascertained that ihcy 

• oxygen with rapidity, and that llie changes arc 
to this absorption. He tried the expecimeni only 

il of turpentine, but he found that the air above 
vrtintand cinnamon, confined in [ihials half ful)^ 
prived of its oxygtn f. He ascertained likewise, 
kdcpendcni of this disposition to absorb oxygen, 
turpentine bos the properly of itrtbibiug a cuiisi- 






>l*i. t£j,inil 14V. 



'.r Tp-vwTc ihe volatile oils asi 

*-. -he rolnlilc oils are healed 
. rxy ukc fire and burn « 
-T:;-i'n^' A vast ijuantity of smo 
.mbuiiion, btsides ihe soot, •■ 

V.tn a|>it3l»1 with water, tlic j 
..i'ilc oils render it n ilky, and 
f — .!'ar odour. Several of then 
: he sugar be afK-rwards di 
. :rrmanciil soluliuii, to wliicli 
.*■ It lias been j(iven. Marguei 
■pertT belongs onlv to the pni 
r oc the oiI». 

'" ife all soluble in nleohol, elh 
^ Tievvary consider.'blv in the fi 
r.::s :o aleohol. Oil of turjientii 
'o intie slowly with that liqi 
nat oil is di^^olved in seven 
eparatci by i!ei:rt'es, and siink; 
~:e action of thf simple combi 



Volatile oils. 4Sft 



I as far as is known, ncUher are they altered Clup. iv._ 
al. When digested upon sulphur at the tem- 
nhire at which the sulphur melts, they dissolve a 
rttonofit, acquire a brown colour, and a disagree - 
it taste and smell. These preparations are call- 
itUtamt of sulphur. A portiou of the sulphur crys- 
Uzcs as (hey cool *. When these balsams are heated 
DDgly, a vast qnantily of gas (probably sulphureled 
"drogen) is evolved so rapidly as (o occasion very 
:ot explosions, unless proper precautions be taken f . 
The volaiilc oils dissolve likewise a portion of phos- 
orus in a digesting heat ; but most of ihem depositc 
whole of it again as ihe solution cools. Hoffman 
tinted out a method of rendering the solution perma- 
nt. It was the following: Triturate together ten 
tris of camphor and one of phosphorus. This mix- 
in dissolves readily in most volatile oils, as in oil of 
Oves, and forms a solution which has the property of 
tndering every thing luminous which is rubbed with 
, and this without combustion t- This seems to have 
ten the solution so much used by Boyle, under the 
,me <>i liquid pJjospborui. 

10. The alkalies and earths act but feebly upon the ofalkaiio 
)|aule oils. The French chemists have proposed to »u'le»«'l^ 
ITC the combinations which these bodies form with 
le volatile oils the name of laiionuhs, which Dr Pear- 



bam it CtjmV of the DijuD Academy, Ui. 3J7. 
oSinaa rdaui a rcniirlubte itoiv of ihe violent cAicti of lucb u 
too hy wiy of oiatiaii to ihe chunun of bis Hmc—Oi-maiiini^ 
ftjt. Ctim. p. 308. 

I liuflhuD, Oiiirv. Phy. Ctm. f . 307. 

Hhj 



;. COMBCSTIBLi.- 



: -.:? ticalcd as Jtbo. -. 
.-.:i wax, soluble ;:. • 
i/r'-oinposttJ by a?i •---•- 

/it it liu'J a]>pro:;tl.Li: : 



.Vi 



... 1 



I -. 



.. .'iS much kss :iclion on tr.ir. 
.T. Acliurii's trials it clissoiv j *. :. 
"; oil of sassafiiis. 'I'hc jjrr::,:. c... . 
.- ilftrcd 1 . 

*. . acid is tliruwii upon them :.uciucr.:Vyk:: 

. J. ."wtd ilate, it acts uith such energy l> '...v. 

:* . but wlicn sullicicntly diluted whh v.-*f 

—.^-m, and converts them into a vcllo-.v siU 

^.»r to resin. Uxvinuriatic aciii atr^i.iih' 

^ -- 'hough with less energy. 

. action of the volatile oils on ntetais iia^no: 

' .-. z aed with care, but it caiinot be rcinarkabk. 

,:— _• . ha^ tried the ciVccl of some ct fiie Snl's ■..♦ 

- .- .::^n several volatile oils. Tlie foil owir.ir art 

■.-:. i:ctTtai;;c.J by lliis chemist . WIjCII oil ol rcit- 

--•* i'-iJt o\i'r niuaie of mere ;ny, the salt is gr.jLL- 

_ .r.:m;)'.ysid, ..: il tlic i.il acquires a dcej) colo:::. 

.-- -:-ale (if mt.viiry, iii hke manner, deeper.s if- 

: and incrcu>es ilie consistence of oils of ci:iur., 

.;rrru, hy sop, lavt:ijir, rosemary, and pep-jcimiu!. 
5-:lcitiial die s.»:iie tin.e partlv converted xr.romLr!- 
.It of mercury. Neither the mi;;iu:e of mercury, nu: 



• /firr. Jf Pijis. IT:. 4C9 
, f MJUmmt ^ Clynit of die Dli;.n Acitd^Jr ; i. .:c : . 



VOLATILE OILS. 497 

the sulphuret of that metal, produce any change in the Chap. iv. 
oils of lavender and rosemary ^ but by this last oil the 
red oxide of mercury is converted into the black, though 
the oil does not experience any sensible charige. The 
(ixymuriate of antimony is likewise decomposed by the 
oil of rosemary *• 

13. From the effects of the acid supporters on the vo» 
latile oils, and from the products which they yield when 
burnt, it has been concluded that they are composed of 
hydrogen and carbon, sometimes united with various 
proportions of oxygen according to circumstances: but 
qo exact analysis has yet been made of any of them. 

14* Volatile oils are applied to a great number of uses: 
Some of them are employed in medicine ^ some of 
them, as oil of turpentine, are much used to dissolve 
resins, which are afterwards employed as varnishes* 
M'ot to mention their employment in painting and in 
perfumery. 



SECT. IV, 



OF FIXED OILS. 



A HK fixed oilsy which are of such extensive utility in Discovery. 
the arts^ were known at a very remote period. They 
are aientioned in Genesis, and during the time of Abra- 
hmm were even used in lamps f. The olive was very 
early cultivated, and oil extracted from it, in Egypt. 

y ■ 

• Am, dt dim. zlviL 66. f Geo. Xf . 17. 



489 

^. _, -^f allydeposi- Chap. IV.^ 

""**^"^-^-itf' ^ . :»o in the eggs 

^^ *" J" ■" in several parti- 

:.,.^ ^ ■ articulars in cora- 

^ i all the fixed oils is 

.leir diflFercnces to ac- 

jomplctelj ascertained, 

•erto been made ; but it 

^ : oils hitherto tried have 

e products. In the present 

c would be useless to give a 

all the fixed oils, as even the 

.m have not been accurately as« 

aallj a liquid with a certain degree Propertlei. 

vig to the sides of the glass vessels in 

.ained, and forming streaks. It is 

.ransparent, having always a certain de- 

, most usually it is yellowish or green. 

J is sweet, or nearly insipid. When fresh 

jr no smell. 

it also in the vegetable kingdom a consider^ 
r of bodies, which at the ordinary tempera- 
tmosphere are solid, and have hitherto been 
IS fixed oils. Palm oil may be mentioned 
pie, which has been lately subjected to a 
imination by Dr Bostock f . The various 
sed in India and Africa as substitutes for 
BS unguentSy may likewise be mentioned. 



^9 ▼>>• 319* 



"•Tt ▼!«• 3*9- 

lOa?S /NrrM/| ZTt. i6u 



40O COMPOUND COMBUSTIBLEf. 

Book ir. jviojt pf them are obtained from the seeds of trcct ; dif- 
< i ferent species of the basna, a:> the butyracea^ longifoSot 

laiifolia^ obovata^ yield this butjraceous matter. Tbej 
have been described b j Dr Roxburgh $• The shea or 
batter tree of Africa described by Park, seems abo to 
be a species of bassia. These substances, from the ex- 
periments of Dr Bbstocky appear to differ a littk from 
the liquid Axed oils in their properties, and to approach 
the nature of ^vax. Thus they are sensibly soluble ii 
alcohol and ether, and do not combine so readily with 
alkalies as the fixed oils. 
Specificgno 2. All the fixed oils hitherto examined are lighter 
^*^' than water ; but they differ greatly from one another ia 

specific gravity. The same difference is observable is 
different samples of the same oil. The following Tabk 
contains the specific gravity of such oils as have bees 
examined. 

Oil of palm * • • • • 068 

Hazel-nuts* 041 
Poppies* ••939 
Linseedf ••032 
Almonds* 932 
Walnuts* ••923 to 947 
Beech-nut* 923 

Ben* 917 

Olivcst ..013 
Rape-seedf 013 
Cacaot •• 892 
ActiaasT 3. Fixed oil does not begin to evaporate till it be 



\ NMiolton's Jmt, III. 371. 

* FabroDi, CreU'e AmmaU^ t797f ii- ISJ. 

t Shaw's B^le, ii. 346. % Bri 




FIXED 011.3. 

1 above the boiling point of wstcr. As the heat Ctap. V. 
eases, a pretty copioas vapour maj be seca rising 
, but the oil does not begin to boil till it is 
d nearly up to the temperature of 600°. At that 



lys 



Uperalure il may be di&tiikd over i but it Is alwi 
aomcwliat altered by the process. Some water : 
acetic acid seem to be formed, a little charcoal remains 
ia the retort, and ihc oil obtained is lighter, more fluid, 
and bas a stronger taste than before. OiJ, thus distilled, 
was formerly disiinguished by the name oi phil(uophi~ 
satoU. During the distillation, a great quantity of 
heavy inflammable air is oblBined. 

Fixed oil, when in the state of vapour, takes fire on 
tii« approach of an ignited body, and burns with a yel- 
lowish white flame. It is upon this principle that can> 
dies and lamps burn. The tallow or oil is first con- 
wetted into the stale of vapour in the wick ; it then 
takes fire, and supplies a sulHcicnt quantity of heat lo 
convert more oil into vapour ; and this process goes oa 
while any oil remains. The wick is necessary to pre. 
seat a sufljciently bmall quantity of oil at once for the 
beat to act upon. If (he heat were siifiiciently great to 
keep the whole oil at the lemperalurc of tiOO", no 
wick would be necessary, as is obvious from oil catch- 
iog fire spontaneously when it has been raised to that 
temperature. When oil is butm in this manner, either 
in the open air or in contact with oxygen gas, the 
«nly new products obtained are ivaier and carboair acid. 

When exposed to the action of cold, fixed oils lose 
ibetr fluidity, and are converted into ice ; but this 
chxuge varies exceedingly in different oils. 

. When fixed oils are exposed to the open air or to Attloi 
dilferent changes according to ""■ 



4d0 



COM ^ES, 



**— V fcrent species of - of absorbing oxTttt- 

latifoUa^ obovat. -.tic more and more vW 

liave been dcst solid state, being apni. 

butter tree of . :- Now there arc sciw 

be a species (- ..ircncy alter they have \jt- 

periinenis of ' .ccomc opaque, and assumt 

the liquid fr. r wax. This circunristaT.u 

the nature <• -iv'sion of uic fixed oilsin'.8 

alcoliol and ■ remain trarisp:ireiit art caM 

alkalies us -^ :Jiai become o].at]ue are called 

^p .ciiiogr:;. -. All ' 

than water ^ used as the vehicle of paints ard 

specific gi -=• '^u'f poppy, and hemp seed oils, 

different • • I'hcsc oils in t?jeir natural state 

contains ' -<rof drying oils but imperrectly. To 

examim. .-:■•'''<? use of the paii tor and vanii^h 

.rr^^^ied lor some time in an iion pnr. 
.,.^vtjZTt partly decom|>oscd ; abundaijcc 
^^cror and of carbureted hydiogen g:i% is 
^^KTttm. They bftome dceprr coloured, 
. .n-r«rconsisti-nry. it i^ coinruon for y;mt 
^,^,:s;ihem nn fm-, to jjHou iht^ni to burn for 
^ -:. r f rimruish ilifii. bycoveiinu up the ves- 
^ ...-ifctvare coiiuuitd, and to coniiiiue the 
^^.:,:kr acquire the proper dc-^qree of viscidity. 
|.3j;.'S0r*s they lose their uj.Ltut.us qualify in a 
irt:***^' ^ ^^ "^'^ '^ ^^^vr a ^r,,.H..jr stain upoa 
-^Uiionof ^aiipproach the nature of resin«, with this dif. 

^aaihey do not bccomf bntile, but retain a 
^rfw«hnessand ducf.ify, not unlike whario 
iris called wought rosin, or shoemaker's ro. 
iBCOmoion also in prepaung the drying oijs lo 






heat. 




^£D OILS. 493 

tie litharge. The change which ^P'Hr.^ 
iy this process has not been pre- 
'^ Probabl J they absorb oxygen from 

ow that they undergo a partial de- 

-len they burn for some time^ their 

is much more completely destroyed 

lethod which has yet been 'practised r 

iowed frequently in preparing the dry- 

-^'amishes, and always for printers ink^ 

es to be as free as possible from all unc- 

las been found preferable to all other oils for 
k ; though the dark colour which it acquires 
-iling renders it not so proper for red ink as 
;. Linseed oil is considered as next after nut- 
:iis respect. Other oils cannot be employed^ 
.c they cannot be sufflciently freed from their 
osity. Ink made with them would be apt to 
e off and smear the paper while in the hands of tho 
k-binder, or even to spread beyond the mark of the 
pesp and stain the paper yellow. The process for 
making printers ink is as follo\ts : 
The oil is made to boil in an iron pot only half Printers 
filled, set on fire, and allowed to burn for half an hour 
or more, then boiled gently till it acquires the proper 
consistence. In this state it is called the vamisb. Two 
kinda are prepared, a thicker and a thinner. The 
thicker ia of such a consistence that it draws into threads 
when cold like weak glue. This varnish is afterwards 
groand with lamp-black in the proportion of two ounces 
and a half to sixteen ounces of oil. When newly pre- 
pared oil is used for making ink, it is said to be neces- 
sary to add a little boiled oil of turpentine and a little 



COUFODND COMBUSTISLES. 






litharge ; but iliis is said to have the eficct of cua^ 
the ink to stick so Grtnlj to the typ«s, that it oa<nk 
difficulty be removed. Old oil df>es not nqain dji 
add! I ion *. 

Oil prepared by the process above described, istn 
insoluble in alcohol and water, but it iiniiea leadSy la 
more oil. It dries into a tough maas like turptnot^ 
and afterwards is scarcely msceptible of nniting widtoi 
Dr Lewis found ihnt linseed oil, when thm conv 
into a thick varnith, lost ^th of its weight i when b«U 
till it became qiiiic stiff wlicn cold, it lost ncaHy 
of its weight f. The property which printers ink htt 
of adhering to moistened paper shows that the oilyii^< 
lure of the body ts greatly altered. In tiome respecuft 
has approached the nature of mucilage, though rn otbctt' 
the difference is very great. 

5- The Jat oUi, when exposed to ihe atmi 
gradually become thick, opaijue, and while, and anm 
ail appearance very much resembling wax or talloi 
Olive oil, oil ofsweet almond*, of rape-seed, and of be 
belong to this class. 

When oil is poured upon water, so as to fonn a t& 
layer on its surface, and is in that maancr expowd 
the atmosphere, these changes are produced much tog 
cr. Berlholtet, whu ttnt examined these phcnomcaa 
with aiiention, ascribed them to the acttoti of light: bat 
Senncbicr observed thnl no such change was prodiued 
on the oil though ever so lung exposed to the Itgbi, 
provided utmoiptterical air wis excluded; but itistit 
took place on the itdmiuion of oxygen gas, wbethct tlit 



• l«ri>, nih Cm. \ 



rrxEO OILS. 

was exposed to the light or not *. It cannot be 
lublec), then, that it is owing to the action of oxygen. 
It U supposed at present to be the consequence of the 
absorption of oxygen and ics combination with 
oils. 

:tion of fixed oils upon the simple combus- 
very remarkable. 
Hydrogen, as far as known, does not act upon them. 
When they arc filtered through charcoal powder, they 
'ttre rendered purer; but on account of the great difli cut- 
ty of separating the charcoal from fixed oils, it cannot 
be employed with advantage for purifying them f . 
Slack paint is usually nothing else than charcoal in 
some state or other ground up wiih a drying oil. 

The fixed oils likewise dissolve a small proportion 
ef phosphorus when assisted hy lieat. The combination 
■succeeds easiest if a mixture of oil, water, and phos- 
phorus be boiled for a little in a glass vessel. These 
«ily phosphurcis emit the odour of phosphureled hy- 
drogen, and yield, when distilled, a portion of that gas. 
When rubbed in the open air, or when spread upon the 
surface of other bodies, they appear luminous, in conse- 
quence of the combustion of the phosphorus. When 
hot oils saturated with phosphorus are allowed to cool, 
the phosphorus crystallizes in octahedrons, as Pelleticr 
ascertained. 

They readily dissolve sulphur when assisted by heat. 
The solution assumes a reddish colour. When distill- 
ed, there comes over ttgreatqaantityof sulphurctedhy 



Action of 

buKiblu. 



t Kdi, (^rcS'i Aiu>ali> iii. 174. Eogr, Trw. 



3 COMWDSTIBtK, 



:^ ^aluiioik ii alioMrcd ts ai,^ 



U^ 



cryitah. By ihis ptonsKk l* ^, ■ 

.1 rrgular octahedropi. ■ -■■ 

i.-c all insoluble in watei. Vm 1 
.- riinid, i!ie mixture beconKitsftj, 1 
.irs ^adually tcpnrate and iwianji 
.<;rience uf 3 inucilstginDUtiubstso, I 
_ --r-nli tile oil froniseparaiinj^, aniK- 
--, :> permanent milkincH. Such »ii 
-nLioiu. They are oflen fonnej kj 
iL-di, as almond;, with waic: ; 
— r«»Ty to form an cmuUion, chI id^h 
^^« >fn3eat in (he need, 
-^it oiii arc insoluble in itlcohol. TIm^ a 
— ..hV in it cvcfi after being thickened bjr In 
b« united to an alkali, and afterwi 
. .,d(l, they will be found to 1 
cT^vof dissolving in alcohol i 
■ ,1 (iergone an alteration in iu c 

'rc,.l lo an alkali*. 
^ .Lrc aUo insoluble in clher; 
.:''■. each other, with volatile oils, a 
■riiminoui and resinous substancts. 
,^««Jk*Jics unite readily with the fixed oils, V 
^-iT— ""' compouiuU called loafi/. The I 
^v ram (bete 'ombinationi more rcadilj than 8 
■ ^ The earths likewise combine with itM 
^1% and forni a kind of soap insolnbU ia i 
^ 4 tr efare tiel capable of be iog applied tol| 
^0 :a common soap. 



u dk CtjHH ul ibc Dijon AcaJemf , iU. 40 



40t 

.^ IS known at pre- ^ChI^IV^^ 
. .. iicr has the muriatic Acid0» 
.'iiusphoric acid, when 
;i , and gives them a pc- 
• .^isttd by heat: a proof 
t'lie sulphurit acid acts with 
he oils become immediately 
i'lily the properties of bitumen 
-.riiiui^nce of the action. If the 
I main long enough, they are com- 
, water is formed, charcoal precipi* 
. evolved f • Other products doubtless 
. ?.j)pearancey though the action of this 
is not yet been examined with sufficient 
acid acts with still greater energy. When 
dcnly upon the drying oils, it sets them on 
I lie same effect is produced upon the fat oils, 
I'd the acid be mixed previously with a portion 
sulphuric. When the nitric acid is sufficiently 
I, it converts the drying oils into a yellow resi- 
;ke mass, and the fat oils to a substance very like 
. But the action of this acid opon fixed oils has 
I been sufficiently examined. 

Bj attempts have been made by chemists to form Acid toaps. 
Dcnt compounds of the concentrated acids and oils 
tbe name of add soi^s. The only acid which 
ond to answer was the sulphuric. Achard pub* 
m number of experiments on these compounds, 
dissolve in water, and lather like common soap ^ 



-l.ivl 



* Elmemi ie Chemie of the Dijoo Academy, ui. 14^ 
t Fourcroj, vii. 330. 

1/. //. I i 



_ 409 

.encc of an oint- Chap. iv. 
»vater decanted off. 
^ _ ihe consistence of a Sweet pri 

- - ." Schecle termed the °P^'''°* 

-» t crystallize, is solu- 

converted into oxalic 

■ ^- . When heated, it is 

*- ^ n oil, and partly volati- 

.ice he obtained also from 

; rom oil of almonds. Even 

.) yielded him a little of it *• 

^ .pposed to exist in all fixed 

;.'ir rancidity by putrefaction. 

ne degree diminished by agita- 

completely destroyed. Mr Dos- 

itation with the fixed alkaline so- 

e answers the purpose sufficiently 

Is for burning in lamps ; but that 

crty of coagulating a portion of the 

i-er may be prevented by adding a 

g brine, which occasions the separation 

odies from the oil f . 

oil is burnt, the only products arec arbonic 9*^P?**T. 

, . tXOD of OlU. 

.er. When repeatedly distilled, or when 

agh a red hot tube, it appears to be com* 

iverted into water, carbonic acid, and heavy 

'jle air. Lavoisier analysed olive oil by burn- 

a vessel filled with oxygen gas. During the 

oa there was consumed 



k*s O^fmn. ii. 189. f NicholiOB*^ Jemr. v. 5. 

Ii2 



COHfODHD COamSTIBLZS. 

Of oil 15"I0 graias tn^ 

Of oxygen gu 50*86 

Total 00-65 

The products were carbonic acid and water. 

tonic acid obtained amounted to 44'50 gnini; 

weight of the water could not be accuiatdj uecm 

ad i but as the whole of (he substances coniamcd « 

■ Converted into carbonic acid gas and water, it ttt 

l<iSent, that if the weight of the carboaic acid be t 

k tracted from the weight of theie substances, theie a 

I Htnain precisely the weight of (he water. Mr Lai 

■tier accordingly concluded by calculation, thai 

«ight of ihe water was satSgrains. Now theoD 

^fity of oxygen in 44*50 grains of carbcmic acidgu 

?*04 grains, and the oxygen in Z2' 1 5 grains of m 

I 18'S2 grains 1 both of which tnken together tau 

50*90 grain*, precisely the weight of ibe ozygtnj 

•in ployed. 

The quantity of charcoal in 44*50 grains of cmIm 
acid gas is is 47 grains; a'ld die quaniiiy of bj 
in S2*1S- grains of waier is 3-32 grains i both of wl 
when taken together, amount to IS'IO gtatni, wbi^ 
the weight of llie oil consumed. 

Il follows, therefore, from this analysis, that 15" 
grains of oil ore composed of 12*41 carbon 

S'32 hydrogco 
P4Hive oil therefore is composed of aboot 
19 carbon 
21 hydrogen 



■■ lur. ijtf, and /-r. A fiy. tat ijS; , Jttf. 



rrtED oits. 5 

This, however, can only be considered as a very im- Clup . i 
]>CTfcct approximation towards ihe truth. The fixed 
oils no doubt vary in the proportion of their constitu- 
ents; and the pheuomena of their decomposition lead us 
to conclude, that many of them conlatn oxygen as a 
component part *. 



Besides the volatile and fixed oils, there is another Poinnou* 
act which exist pretty frequently in the vegetable king- °' 
doni. Their chemical properties are intermediate be- 
tween the fixed and the volatile oils. Like the volatile 
oils they dissolve in alcohol ; but like the fixed they 
cannot be distilled over with that liquid. Hence they 
may be obtained by digesting the vegetable substance 
that contains them in alcohol, and then sepHraling the 
alcohol from the oil by distillation. They have all a 
strong acrid Uste, and most of them possess poisonous 
Qualities. The alcoholic solution of some of them has 
tlie properly of precipitating sulphate of iron of a reddish 
colour, which becomes green when mixed with an al- 
kaline solution. Vauquelin detected an oil of this tia. 
4 lore io the root of thehelleborus hyematisf. A similar 
oil appears to exist in tobacco and in many other plants. 



* Seiidci the oili wbich niit read; fcrmed Jc die Tenable ind inr- 
aal kibijdani, ihtrt tre ■ variciy o\ oikrn whirti ifc ebuined whtn 
aoinud or vcgrt^bl: bodlct arediU'llcd b\ mc-int of a h»t above Uuc of 
boiliog walcr. TkfU uililiaTc recei*i-d ihc ippcHitiori of rrfyrnm^iic, 
fceouK ihtj are f'^nned by the iLtion of bre. I'hcf h>iT« D.icr bc^ 
CMinined with aniniioO[ bul mod of them term tn pfi^stw iht pcap^n- 
tiaaf the voUttile oUi. Their oJour ii alwiyxs.ctdiuglj diB(rei.iU(^ 
■adtkelr U(te «crid. 

i J^A Afw. fSia. N,it No- iJiil Sa. 



couromrD xouiostibles. 



OF BITUUEKS. 



1 HE term hitumtn bai often been npplied by cbeaiin 
to kU the inflammable substances that occur hi the eutb; 
but thit UH of the word is now so far limited, tbu n 
phur and mtUiti arc most comioonlj' exclitdcd. 
would be proper to exclude amber likewise, and to ^ 
ply the term to those fossil bodies onlj which hsvt i 
certain resemblance to oily and resinous substanti 
1b this restricted sense the word is used ia the ptM 
Section. 

Bituminous substances may be subdivided inU t 
cUues ; namely, bltuminoui oili, and bitUKMu, proptd) 
so called. The first set poiseii nearly theprapertiag 
volatile oils, and ought in strict propriety to be c 
with these bodies ; but as the chemical properties i 
bitumeni have not ycl been investigated with I 
precision, it was deemed rather premature to i 
tbem from each other. The second set possess propcfi 
ties peculiar to themselves. Let us endeavour to ( 
schbc the substances belonging to these two clauci a 
&t u pouiblc. 

I. BtTL'HIXOUsOlL&. 



Omit two species of hiiumioous oils have bees 
i by chomiit^ Others iadccd bave bi 




\t^, but xhc'xr exis 



MEWt. St^ 

ICC lias not been sufficiently ChKp. ly. 
^^ccics lift c.>ik.;l fitrtkum, — 

malila or tfa^vjox ,■ the first la liquid, the second 

]. Pe.roleum is an oil of a brownish yellow tolcur. Petroleum. 
Vlteo pure, ii is fluid aa vial^T, ird >-iTy vdaiile ". Its 
peoi6c gi3vii)< VBiici from T lO tu O-STb-t". Jl ttass 
ietU'>at smciu Wlii.ii ikealcd, ii may br distilled over 
vnitioui altei'tion. Ii uoiio* wiih alcuhol.eiher, voia- 
titc and fixed oils, >ii>d, a» hir m knuwn, po&seasesall ibc 
cbaracicrs of volatile oilii. 

Petroleum is found in the earth in TaHous slates of 
Hiriiy i soniciimes without any mixture of foreign 
sobsiances. In this state it is usually diilinguislicd by 
the name of naphtha, and is said lo occur in great abun- 
■ dmnce on the shores of [be Caspian and in Persia. It 
ACcursalso in diSereni parts of Europe, especially Italy 
' and Germany, When less llnid and darkt^f coloorcd, 
' h it commonly caUed petroUum. It is supposed to owe 
'Utax increased spissitudc and deepened colour to ilic ac. 
tion of ilic air- When distilled, it yields a quantiiy of 
pure petroleum, while a portion of bitumen of the con- 
sistence of tar or pilch remains behind. When long 
exposed to the air, peiroleuni becomes bUck, and ac- 
- quires the semifluidiiy of tar. In this slaic the greatest 
part of it is insoluble in alcohol \ so that it has assumed 
tbc state of true bitumen. 



■ ThcmUtilityMenii l<ib>TcbceiiuTcr-r. 
On mimg mil recufiftl petcalcuni with wi 
(he witcl CDuU be rcid )y •lixillttl onr m 
whote peuoleam teauiaed behind. 

t See Kifwui'i tdmirMtg-^, ii. 43. 



lib) aLkichemlLilirriten. 



a moilcrate hat, while ihc 



AAoicaa U lUEi! IB those covatrici wbcTC itibi 

■dmrnmau ha^et, «m1 of the propez bimncu, 

X ■iiJiii wtdi bcQIty. 

^ £«a-(M«, or mtJiha, U a solid sobrtsHC Ifl 

■te Bulul lake ia Sabetia. It U «rbiu, 
riMHiii. and •■ coohig usuoiet Uie co«s« 
ccnK. It duMtm mdil^ ia Blcohol, and i 
mpecu apfwan lo poucsi Uw chancwn af ft a 

iMile oil- lu propntiec, bowsver* bft'vv 
perfectljr czamiDcd. KUproth found tbu. • 
nUtancc wu obwiacd bj dittilliag ■ 
eta/, called f<irfi (m/ bj the Gcrmat)* 

The ubitancc described by ILifwan mdcr.liw 
auMtral lallovt, 2nd lud to h»ve been fiMiod an I 
«f Fuluid, in the Swediah lukei, uid ia a feital 
Strtuborgb, seems to appToich very nculy to 
lu tprcitic gvarity is O'llO. Ii it white. bni 
fSpei like oil, mells wlieti healed^ and 
blue Rune and much smoke -, dissolves inj 
ia bot alcohol, but icadilj ia olive oil f .. 



II. ProPEK BlTVMCKS. { 



TuE true bituminous substances maj 
cd by the Tollowing properties: 

1. Ttie^ are cither solid or of the ooostl 
a. Their colour is usually brown or black. 
3. Tbej have a peculiar imcll, or at least I 



BITDUEKS. 

rubbed. This smell is known by the name 
HtHtninous odour. 

4. They becooae electric by friction, though not ia- 
lUtedf. 

5. They melt when heated, and burn nith a strong 
S bri^lit ilame, and much stnoke. 

- 4. They are insoluble in water snd alcohol, bat 
live most commonly in etber, and in the fixed and 

Volatile oils. 

> T. They do not dissolve in alkaline leys, nor form 

aoftp. 

S- Acids have Utile action en them ; the sulphuric 

Bcarcely any : the nitric, by long^ and repeated diges- 
tion, dissolves them, and converts them into a yellow 

lafastence, soluble both in water and alcohol, and simi- 

ijar to tlie product formed by tbe action of nitric acid ou 

Btcatait. 

The bitumens at present known may be reduced to 
Ifatee; namely, aipbaltum, mineral tar, and mineral 

leaottcheuc. Bitumen has been found aKo united to a 
resinous compound, in a curious substance first accurate- 
ly examined by Mr Haichctt, to which he has given 
the name of retinasphallum. United to charcoal in va- 
rious proportions, it constitutes the numerous varieties 
et pit'CoaJ, so much employed in this country as fuel. 

J. Asphalium. This substance occurs in great a- ' 
tnindance in different countries, especially in the island 
of Trinidad, on ihe shores of the Dead Sea, and in Al- 
tHUiia, where il is found in vast strata. It is supposed 




COMfOOVD COHVTSTIBLei. 

that it was first liquid, and thai it acqaired u1i£if 
by exposure (o the air. > 

lu colour ia black, with a shade o( brown, red, a 
grey. lis specific gravity varies. That ot Albani^ 
ai ascertaiocd by tUaproih, was I'SOS * ; but a «u' 
somewhat coittaminatetl with carih. Kir» 
specimens, found the ipeeificgraviiy to vary from |'B 
to 1*163 f . Klaproth hat lately published an auclfiivl 
of the asphaltum of Alb:ii)i3. 

He found it insoluble both luacids aod alkalies, » 
in water and alcohol ; but soluble in otU, peunl 
and sulphuric ether. Five parts of rectified \ 
dissolved one part of asp halt um without the aiuiti 
of heal, and formed a blackish brown solution, win 
by gentle evaporation left the atphalium iu the ■ 
of a black brown shining varnish. The toluiiou i 
ether was of a pale brown red colour ; and when enpo 
rated, the asphalium remained in the state of ati 
fluid substance of a reddish colour, still insoluble il 
alcohol. ' 

A hundred grains of this asphaltum being distilled ii 
a retort, by a heat gradually raised to redness, yicti 
the following products : 

CnkB 
3fi cubic inches (German) of heavy inflammable air. If 

A light brown fluid oil 

Water slightly tainted with ammonia , 

Charcoal 

Ashes 



104 



BITOMEHS. ~ 



SOT 



KKftsbes consisted chiefly of silica and alumina, with Clap. XV. 
me iron, limr, and mangaaete*. 

The asphaltum found in Albania is supposed to have Ukl 
nttituied the chief ingredient of the Crtetjirt. The 

Egyptians are said to have employed this bitumen in 

iMbaJming. It was called mumiamaeralii\. The an- 
its inform us ihat it was used instead of mortar in 

uilding the walls of Babylon. 

:. A^phallum is seldom absolutely pure; for when 
ihol is digested on it, the colour of the liquid be- 
imes yellow, and by gentle evaporation a portion of 
troleum is separated J. Mineral tar seems to be MineoJwr, 

Dthing else than asphaltum contaioing a slill greater 
iportion of petroleum. When alcohol is digested on 
a considerable quantity of that oil is taken up ; but 
lere remains a black fluid substance like melted pitch. 
It acted upon by alcohol, and which therefore appears 
possess the properties of asphaitutn, with the ezcep- 

ion of not being solid \. By exposure to the air, it ta 
id to ussume gradually the stale of asphaitutn. 
3. Mineral caoutchoucisasingularsubstance.hither. Minrnlca- 
found only in Derbyshire. It is soft and very clas- 
, not unlike common caoutchouc, or Indian rubbfr, and, 
;e that substance, it may be employed to eflace pen- 



)Uapro(h'> Jiitrfrj', iii'i'''' i Waium'a Cttm, Eiitjiita.^, 

X Hatdiclt'i Oi.irwH'c*. (A lit Chai>i< •/ itmi <•/ tin PrimiifUi rfVtjt- 

btlt BilMmi*. Pbil.lruiti 1804. 

( Cboniui and minEnlogiHt luvc unittd mineral lar 10 pclnikum 

it be true ihii f'Tt pctrolcuBi ii inulubie in alwhol, 

i« rigKl : but I laipect a miiuke. 1 had no opportu- 

•f trying u/i'^,- hut ihc pntcn (xtroleum I have bcm able lo 

R KadUjficIdi to alcohol, unlcwithM been icft 01 poMd 10 the air. 



COHPOmrD COMBUSTIBLES. 

cil marks from paper -, but it loUs tlie papec t.'iaild.] 
Itx colour ii dark brown, *otno(iinc> with a ifaiAt 
^rceii, St olhrr times of nrJ. The fiitt iiccoum o{ 
pi:bllTihed by Dr Litter in the Philosophical Ti 
tipiofor lets *. It occuicil in an old fofiakcan 
Dcrbytliire. He calU it a subterraneous fungiu, mA\ 
nnccrlain whellicr it belongs lu ibe vegetable « 
al ki"g(loms ; but rather inclines to the foraitr 
on, and hints that it ma^ have growD out o^^ 
btich prop! usrd in the mine. It waa &i 
deiciihed by Mr Hatchell. Delan 
mined its properties i and an analyaia of it hi 
Ijr published by Mi Klaprotli. 

arding to Klaproih, it resists the aciioD of i 
all liquid menstrua ; neither .-ilcohol, alfcalics, 
acidafTecttng it. Even oils were not found by hli 
'dissolve it, though Oclameiherie assure* □« that b* 
taincd a solution of it in nlivc oilf. Petroleum lOb 
f ceedcd best with Klaproih, assuming a brigtit jcUam 
ij, while the caoutchouc wasrenderedtranspanai;. 
When heated it tnells, tskcs fire, and burnt iriih i 
bright flume and » bituminous smell, Xhe melled niM 
Still continues adhesive, and may be drawn oni into 
threads. It is now soluble in oilxf. 

One hundred graius of this substance being distilUd 
I gradually raised to a red heat, yielded 
following products : 



i.p.«i7S. 
t tiilngt, jii. 10$. 




Binrxiifs. 501 

■ Gn!ru. Cu^ iV 
^ibic inches (German) of heavy ioHam- T 

sair >- 13 75 

4 inches (German) of carbonic acid gas . . \ 

A brown thin bituminous ail... ...,73*0 

Water slight); acidulous 1-5 

Charcoal 6*25 

Ashes 5'5 

lOO'OO 

The ashes consisted oflime and silica, with some iron^ 
sulphate oflime, and alumiua*. 

Mr Haichete supposes the elasticity of this substance 
to be owing to a quantity of air confined between its 
pores. 

4. The retinasphaltum of Mr Hatchett is a substance Kniot- 
blthcrto found only accompanying Bovty coal, ia De- 
■vonshire. It was lirst mentioned by Dr Millesibut 
■we are indebted to Mr Hatchett for every thing luiows 
respecting its chemical properties. 

This substance has a pale brown ochre yellow co- 
lour. It is very brittle, and breaks with a vitreous 
fracture. Its specific gravity is 1'135. Whenheld in 
the band for some time, it emits a slightly resinous 
smell. When heated it melts, smokes, bums with a 
bright flame, and emits a fragrant odour, at last tainted 
Wiih a bituminous smell. The melted mass, when 
cold, is black and brittle, and breaks with a glassy frac- 
ture. 

Water does not act upon it; bnt it is partially dissoU 



• Klaptotii, BtUfZh 



510 COMPOUKB COMBUSTIBLES. 

BcMk IT. ved by alcohol, potash, and nitric acid ; the dltsolnd 
^^"*^ ' portion having the properties of a resin ; the undiadnd, 
of asphaltum. Mr Hatqhett analysed it,* and foiod 
it composed of *. 

55 resin 
41 asphaltum 
3 earths 

PSfe^oal^or 5. Ktcoal, one of the most useful of all the miaenl 
thfw kmdf. productions, has been divided by mineralogists into va- 
rious species, according to its external appearances, 
and the nature of the strata in which it is found ; bat 
in a chenrical point of view, its most important varie- 
i.Browo ^^' ^^7 ^ distinguished into three sets: 1. Those 
^^ that still contain several vegetable principles^ strictly to 

called, and thus give evident marks of their origb. 
To this head belong most of the varieriet of coal tr- 
ranged by Werner under the head of hro%on coal. Mr 
Hatchett has shown, that in some of the substances be- 
longing to this class there is to be found a portion of 
vegetable extract ; in others, as in Bovey coal, a por- 
tion oi resin ; besides the charcoal and bitumen, which 
constitute the greatest part of its constituents. From 
another species of brown coal Klaproth obtained, by 
means of alcohol, a brown red tincture, which left be- 
hind it on evaporation a reddish bitter extract par- 

_, . tially soluble in water f- 2. Those kinds of coal that 
%, Black -^ . 

coil, contam ncx traces of unaltered vegetable principles^ bat 



« HaUhett,on the Charngt •ftmfftbt Primages •jVtgeiahia t9 Bi' 
twauM. put, rr44w. 1804. 
t Beitr^', iii. 3 as. 



BITUMENS. 



511 



ure composed of various proportions of bitumen and /^'^P- ^* 
harcoaly contaminated like the former with earthy 
natter. To this head belong the varieties of coal ar- 
ar>ged by Werner under the name of black coal^ which 
ibound so much in Britain. Kirwan has given us a 
'erj ingenious analysis of several specimens, founded 
Lpon the property of nitre to deflagrate with charcoal^ 
>ut not with bitumen. By throwing coal reduced to 
mall pieces into a given weight of melted nitre, he ob« 
lined a defl;igration, and judged of the proportion of 
harcoa] present by the quantity of nitre decomposed *• 
^e following is the result of his analyses. 



loo Parts. 



C mnel coal 

Slate coal 

Whitehaven 

Wigan 

Swansey 

Leitrim 

Newcastle 



Chircoal. 


'■ '.iineii.| 

1 


75*2 


21*7 


4T6 


32-5 


5T0 


41*3 


61'7 


36'7 


73*5 


23*1 


714 


23-4 


58 


40 



Earth. 



3-1 
19-9 
1*7 
1*0 
3*4 
5-2 
2 



Sp. GraT 



1*232 
1*426 
1'257 
1 268 
1*357 
1*351 
1*271 



A number of experiments on the constituents of dif- 
srent specimens of British coal have been lately 
ublished by Mr Mushet f. He subjected the coals to 
istillation in close vessels, and thus ascertained the por« 
on of volatile matter which they contained. By buni« 
ig the coals he determined the portion of earthy matter 
I each. The following Table exhibits the result of his 
cperiments. 



♦ Kirwan*A M ifro/igy^ ii. ^14, 
t Phii Mag. xzzii. 140. 



COMPOUllD COininTTBLCS. 



WcUh furnace coll.. . . 

Atfrcton furnace coA , 

Builerlj furnice coal ... i 

Welsh stone coal 

Welsh slaty coal 

Derbyshire canoe) coal . 
Kilkenny coal .,,..... 
Stone coal under basult.. I 
Kilkenny slaty coal .. . 

Scotch cannel coal 

BoolavooncCQCoal "J 

Corgccdo > Irish 

yuten'scountydo. j 
Sionewood, Gianj'sCaus- : 
O.ik wood .... 



S'5 a6-O0B 
. 45-S 53-45fi 



2-044 1-335 



!-8332- 
■00 80' 
1-10S4- 

:-oa48- 

I'OO.BO- 
I-8082' 

riosT 

V3o|8(l' 
i-3:54' 

1-00 10' 



4-28S 
2'30l-' 

fl-725 

4 •ass 

£•813 

IS'flOO 

6-525 

4'Pt)0 
3-240 
3-40U 
3-HO 
I1-P33 
500 



1-264 I 

1-3&S I 

40G 



■445 

•♦5« I 
1-403 I 
1*«03 1 



3. Those kitids of coal which neither dmUln m 
of unaltered vegetable principles nor of bitofncD, 
Kcm to consist entirely of charcoal contaminated i 
some earthy matter. To this head belong the diffci 
▼arielies of coal arranged by Werner under ihc id 
ot fitinrt-toat. "I'his kind of conl is less common i 
L Ac preceding. Ii is remsikable for its metallic lusl 
Utd for the slowness with which it eoniumes. Mi 
ipecimens of this coal have been suhjoeied to chenu'l 
analysts ; the resnli was always llic s«m«. I shall 
join a few speciisetis *. 



The firn uulyi:! frj Kirwin (Mlii*,r,f,, \i. j,f.) Tht 
bjr HcrUird i!e Thury. Stt Ccfalcn'* JWr. ». ^tj. 




xoo Pants CharcoaL rartli. 

Kilkenny coal.,««... ••••••97*3 3*7 

Anthracite^* 90*0 10*0 

Ditto • 72 20 

Ditto 97-25 2-75 

Coal of Notre Dame de Vanx 78-5 20 



When coal is distilled, the products vary according to Ptoductil 

fr*m from COAla 

the class to which the mineral belongs. The coals of 
the third class yield no volatile products whatever. 
Those of the second give out abundance of heavy in- 
flammable air ; a .bituminous oil| at first fluid, then of 
the consistence of tar i and water impregmted with am- 
Bapnia* The residue is coif, a species of charcoal ap* 
plied with the greatest advantage to many of our ma* 
hnfiactures. It burns long and equally^ and yields a 
great deal of heat. .The oil has been ^plicd by Lord . ,» :. 
Ikuidonald to the various purposes of vjomub. Coalf 
belonging to the first class yield abundance of heavy 
inflammable air, a bituminous oil, and water either very 
tUgh|dy impregnated with ammonia, or containing a 
quantity of acetic acid, as has been ascertained by the 
experiments of Klaproth and Hatchett. 



VoLJI. Kk 






nUHAU COWOOMM. 



SKHXBKS 0:< THK niMARY COMFOCSDt. 



BtrcH arc thepropeni« of the PfcnWAitT Cm 

B 9 dns of bodies whidi' hn been longer knmM 
I 6d>tr, which hat fce«n cx»iTih)«l with pcealisrcvc,! 
vhtch comprehends m»ny of ihe moar in»port»Bt in 
nienn of chemical rnvcitiganon. 

1'hc sabilnrtcci incliKlcrf ander the nnne of f 
compounrli were Hivnied inlo four scti ; namely, ( 
meidt, colvrijit ttriit, md tvmfvtnt tma^ttihitt. 
turn first Bc» are cowaierparts to each otli«rr ; bolb ll 
compoKd of the mmc tnfrrcdienl», »ni both i 
the Mme subdiviMDni. They conM&t of oxf gca n 
to [he simple combvfirblcs, incomfasstiblcs, or n 
Htid are distinguished bj iheir acid ptepenies, or di*] 
want of that claractcrittic. They may be divided inu 
product) of combuHion, supp^rttra of eomhufiion, andn 
buslihla. 
I Every iaovm prtidart of combustion is a prim 
'' compound i for it is retnarkable, that in all i 
combustion, the bodieswhich undergo it, however o 
plicated a) first, always arrange (hemselvcs so as to fod 
Ihe simplest possible cotnbinationi. The apparcBtci 
rcptiona cossist of subtianocs nhiab hftve Dot in tcalifir 



iergDDC combuitisD. All the producli of coAbtiS'^ 
R kiwwn fti prnoit «rc the fallowing : 

1. Waier; 

■2. Carbonic acid ] 

3. Acid of phosphonix ; 

4. /^cid of sulphur ; 

5. Metallic oxides. 

B tike tBiiiina' >11 the iiwwo ivfporuri of coBibustioB ' 
leJong to itiis cJasi, and arc of courie primary cotn- 
mnds, excepting oxjgcn itself. Theje subuances an 
II decofnposed by the action of heal i a prbpenj which 
ittinguisties ttiem very readily from the products. The 
dlewJDg are all the supporters known to exist, eacept- 
►g BJtygwi. 
1 . All the compounds of azote with oxygen. 
^. All the compounds of muriatic acid with oaygea< 
3. The metallic acidi. 
rhc nature of ihecomhuslible oaidts and adds hubcen 
at imperfccily inveBtigaled. Conaiderable obacuijr^ 
ill bangs over them. As chetQical agents, they ar« 
iferior in importance to oxide and add products and 
lpponer% and much more liable to undergo changes iti 
heir constitution. With a few exceptions, they arc 
triple compounds, containing oxygen united to two 
boinbusiiblc bases, most comtnonly hydrogen and car- 
bon. Sometimes azote seems to enter into their con- 
■litution. 

The colorific acids, strictly speaking, belong to the * 
Mme class, and were separated merely on accountof the 
different purposes 10 which they are applied in chemical 
Investigations. 

The eofflpound combnslibles, there is eyery reason la 
Kk2 



FXIWAXT COMrODHm. 

' beliei^ ire more variable iti theit coastitocnts ihan 
preccdiiit; classes, mod accordingly are more liable 
change th r naiHic. Chtmists have noi yet been i! 
to anal sc ihcjn in a ^atufactor^ manner ; but ihc p 
sent iiaie of our knowledge leads us to conclude, tl 
as far as iheir constliuenis are concerned, they maj 
arranged under ihtce classesi namely, I. Those th»t 
composed of hydrogen aud carbon. Zlhcr and the' 

■~ latllft oils, when in a stale of purity, seem to belong 
tliH class, 'i. Those that are coiupoa«d of bydreftt, 
cm-bon, and oxjgta. This appears to be the case inik 
alcohol, vriib cnosi of iht; fixed otb, and with those n- 
htilr oils that have been exposed to the air, or ate Ix. 
ginning to lose thctr Kuiditj. These oils, by dui 
change, lose their smeU and most of iheir dil^; 
gui'ihing qualities ; but.lbey are in some 
HoTcd by dtstillaiian with ether, which aeeuis lo 
them back to their lirst condition. 3. Those ibai 
Oompoicd of bydngin, carbon, oxygta, and as^ott. 
I^pears lo be the case tvithtlhc bilumrns ; at least if 
■re to judge from the oil, uater, and ammonia, sthklk 
tiicy yield whcu dtatiilcd. 



roeasoTC l^H 
ems ^M^H 
lose (bat ui^ 
9sM«. This 1 
It least if m I 



• T . Book n 






DIVISION m^ 

1 

. , . . .. 
OF 






SECONDARY COMPOUNDS- 



JBt the term Secondary Compound is nneant a combina* 
tion of salifiable bases or primary compounds with each 
other. These combinations are numerous. Thus a- 
cids combine with alkalies, with earths, and with me- 
tallic oxides, and form compounds called salts i the 
earths combine with the fixed alkalies, and form glass; 
oils coiiibine with alkalies, and form soaps. These 
combinations come now under our consideration. 

The secondary compounds, as far as we are at pre- 
sent acquainted with them, may be arranged under the 
five following classe"^. 

1. Combinations of earths with each other, and with Amnee- 
metallic oxides. "^itt. 

2. Combinations of earths with alkalies. 

3. Combinations of acids with alkalies, earths, and 
metallic oxides. 

4. Combinations of sulphureted hydrogen with alka-. 
lies, earths, and metallic oxides. 

5. Combinations of oils with alkalies, earths, and 
metallic oxides. 



ComAtATIIMn Vt SAtTBI. 



CHAP- I. 
P COMBINATIONS OF GARHIS. 



It of ihc «i^rt^J at* cap«ble of errt^ring into com- 

irilh cuch other and with meiaHtc oxide*, and 
log compcunds di^inguislied by various mmies 
ig to their externa] appiarance. Some of these 
Itions aie formed into vessels known hy the 
af slonruwr^, p^rcttaui, tnantel, &c. many of 
ire of great importance in manufstcturcv and do- 
toonoiny. 

class of bodies is cf the highest importance; ti 
fti not hitherto been examined by chemists with 
;rce of attention to whirfi it is entitled. A few 

t}>e compounds into which the earths and i1k 
: oxides ire cflpable of entering have been form* 

still fewer of these have been described with 
m. The subject indeed is dlfGcuU, «nd tilUate- 
not susceptible of acciirncy, because the proper- 
tlte earths, and (he n>et)>ods of obtaining thetn 
'ere anknowu. It is true, indeed, that the great- 
ber of these compounds exist ready formed in 
tcral kingdoDi, constituting the stdid basis of this 
if ours. But sot withstanding the rapid progress 
ibe analysis of micerals has lately made, it is 
rjr imccriBtn whether it would be safe to trust 
lier the result of these analyses ; especially as «t 



UO BECOSDAXT COKrOtlKSS. 

nf^lii ""^ "^^ "^''^ '** form ainliciallj compound! tinitaiiil 
■— y — ' iliow whidi mtt Tcadj formed in the earth. 

Il will be betlCTr Uierefore, to refer the conudtniia 
of ihcse numerous native coinpoMnda to the Second^ 
of this Work, and to satisfy ourselves at ptescntwukq 
gcDcral view of the compounds which the canbt m 
capable of forming, n di-tcription of those i 
which are employed in the manofiactorc of itonei 
and porcelain, and an account of those conibinaum^ 
earths and metallic oxides which form Uw dt£ 
, enamels with which these substances are covered. 1 
t topics wilt form the subject of the two fo)lowiii||| 
I tioDs. 



SECT. I. 

pr EARTflT COMBINATIODS IH GENrSAt-* 



That several of the enrihs have a strong sffmtty ftj 
each other, and aie thtreforc capable of forming combi- 
nations, is a fact now well known to ihe chemical wotld. 
Difficiilirof But il ii by no means an easy matter lo form ihtie 
wih*!""* combinations artificially. If (he earths be mixed to- 
gether in a slate of ponder, they do not combine io- 
timalely ; and as few of ihem are soluble in water, tt- 
coiiTsr cannot be had, except in a very ftvr case*, to the 
intervenlion of ihst liquid. Clicmtsts, therefore, whm 
they wish to combine the earths logeiticr, hav« acirct. 
ly nny other apent to cmpluy eaccepl fire. Thii*grtl 
answers exceedingly well in combining the metals wjlfc 
each other, and eonvcrting them into alloys : 



COllfttftlffldWS of tfAfttHs; 



r 

^■9^' t° 'Ii^ earths the case n viry rfiffttent ; for no' 
SA'lvhic'h can be produced Is snffia'enlly TJolertt to melt 
ai con^derable quanitty of any of the «*»«hs, barytes 
and strontian excepted. ' , .. , , 

It i s true indeed that silica, and perhaps afl the other Their fa. 
earlhs, may be melted by a process invented by Saus- k,^,"™' 
SlftTi He cements a Very minute' particle of quaitz,oi; 
any other tnbsiance whose fusibit^ry is to be tried, to 
& Slendw fibre of eyatiilr*, and crpftses it in thai state 
ft> tfte action of the bloW-pJfj*. He supposes the inten- 
sityoiftlie heal inversely proponional lo ihi- diameter 
»f the g!ofau1e prodtictd. Any heat thfcrefore wImffMr 
may be communicated by means of the blo%T-pif*, hy 
diminishing sufficiently the bulk of the particle subjeoCv , ~..^ .- ; 
«tf lo its action, ■ The limit of intensity is whtmhe 
particle cannot be farther diminished w-ifhout rcndeitw 
ing the globule produced too small to be seen distinctly 
by a microscope, and to be measured by means of tt mi- 
croineleT.' Sausstfre fonnd that the lieat necessary to' 
melt quartz is equal t© 4043" WedgeWobd";- "that which 
niclts alumina is 189^0' Wedgewood't; " ■ ' ' 

The temperature, then, at which live Ahhi nielt n Lawercdb; 
intpnceivably high ;. b*5t the quaiitity'of- these bodier ""^"'"* 
which can be in this manner subjected to -experimAit,' 

' is by far too minute to draw much satisftctory infdt- 
mation from it respecting the nftiure of the compMin^ 

I wrhich the earths are capable of formirig'with eatfi'othet/ 

' Luckily it is in many cases not necessary to have 'itJ 
course to it. It is well known that' several df fhcOie- 



* TM* tfa Uk ccdonHd ttai^dimt itane, talc afttnrardi dncribe^l 



■xeovDuiT cowrourat. 

Ulif which re^ifc ■ vaj high (cmpeiattm lo \a:'a^ 
thwn Is fuuM, Bwlt mdily «rh«a totxcd with > fv 
tion of sonn« oihcr nMuI. Tliux plaiinnm. ih* bh 
iafoiible o/ ihem all, neliimdtly wh«neoinbintd«q]| 
Wtenic. Tb« MRM thing bappcnt with >cvvral of (lit 
earths, s« Conkct firK diK»-cnrd : alumina, for ta. 
atincr. though p«rlnpa the mott refractory of ihra 
■II, enters very »p«c4iiy into fuaioa when mix^d <nik 
a proper prApernon o( tilica and liror. Chemiut Itin 
ta]c«n adiraiitagc af thi* profwrty. They hxTe taiti 
thfl aanhi together in various propontooa, wad tim 
aubjecwd them to heat. The aiSaiiy bnwees thm 
was jodged of ky the degTM of fasion which ihcy utMkr< 
went. Mr Poit was one of the first chemists who hid 
epan this tnsthod of proceeding- His ZJth^ngnvia, 
whicli was ptiblished in I74fi( most hare been ihs rc> 
suit of immente labour. It m^j be coniidcred as tha 
harbitigcr of all the miocralogictl dficoveriea which foL 
lowrd. Achard * of Berlin publfshcd, iit tTSOf a lonf,- 
list of cxpeHcneiitt, in wbich he exposed various mix. ■ 
turea of earth to the heat of a pomlaiu furnace. T>ii( 
wai the first direct tct of experiments on the corobins. < 
(ions of tarthsj for Pott, and Mxcquer and Oarcct who 
followed hioi, had confined the[ntel<rci to native cofflbi* 
nations. Mr Kirtvan, in J 704, published a still mere 
accurate set of experiments f on the same snbjrct. 
Since that time (he combination of the earths has occn. 
pied the atteniion of Morveau } i not to mention the 
intcreuiog cxperiincnfs of KlaprothJ and SaussurejL ' 



• Mm. Btr/i., 1 jgo, p 69. I JUinr -Ugj, i. < j, 

t /Mr. A ric/i ftljiKii.. V III. a^ iBil A»». * Ciar. tiii. si& 



COMBWITTOWI or SART8S, 539 

And the iogenioui speculations of Saussure and Dolo- Chip. t. 
mint •. Bui Ihe mo^i important experiments on this 
subject are those of Darracq + and Chenevix J ; because 
the^ have been made with substances in a slate of pu- 
rity, and with the proper precautions to prevent erro- 
neous icsulis. From the experiments of these philoso. 
pher*, and from the accuraie mineralogical analyses of 
Klaproih and Vauquelin, the following cooKquences 
iiHj bedrawn. 

J. There is an aflinity between most of the different ^"'""^ 
•mbs : But this affinity varies considerably in iniensi- on aih 
tj. Certain earths combine readily wiih each other in 
•lincsi ei.'ery situation, while others cannot be combi- 
ned without difficulty. There are some combinaiions 
of earths which are found native and abundant ; others, 

' An the contrary, seldom or riever occur. 

' i. Certain earths when ttiixed together become very 
fusible, while other mixtures are as refractory as the 
ucBplc earths themselves. The afGniiy between the 
rartha must not be judged of by this increase of fusi- 
btltty; foraeveral earths which have a strong affinity for 
each other do not form fusible mixtures at all. In ge- 
neral, mixtures of earths are fusible only when mixed lu 
certain dcierminate proportions. 

S> The ihtee alkaline; earths, lime, baryles, and stron- Alliilrne 
tian, resemble one another in their disposition to unite ''^ ^ 
with the other earths. Like the alkalies, they com- 
bine with alumina and silica, but show no affinity for 
magnesia nor for each other. Their action on the new 
earths has not been examined. 



mjmr.APtyi. 
I fHl.lrtni.l'. 



Wlipn htTftn xnA alumina are boUed togcthct i>( 

nffic^mt quantiry of wntrr, xhcj crnnbiM, und bti 

two compnands : one of which, containiog an cmq»4 

baryici, rrmaitis in solution ; the otlier, contiiniogri 

excess of alutnma, is in the ataic of nn iniotubU p 

dcr. Wherr bzrytcs iiid silica «rc fused togcihcr u k 

platTtinm ctutiblr, ihey combine, and form i fmlk 

MislcTed mas», of an Bpple giWen colour, whldi ii ih 

I lublc in all the acids, bin imperfectly solubts in « 

If this compound be boiled to water, it separaietiA 

> portions; one, contaiiiin|; an excess of bsrjio,^ 

lolvcs, bntllie pr« scnce of the tilica prevenuthcWfm 

I cr^itilliKing ; the other rctnaint in the 1 

^'tn infoloblc powder. B&rj-tcs, [lunfied in tbe nnl 

^ ^&y. nlwajs contains n portion of siltca, which KpMi 

f babiy takc& from the crucible to which it is prepBieA.) 

) grot is the afnniiy ofibaryies for silica,' tlw iti 

s silica frflm polashf . The afltniiy faciwceail 

ilia aniT barytes i» not strong enough loscparan il 

9 earths when the soluliont of them in the nmci 

mixed together.' Muriates of baryies and alirai 

ibr instance, when mixed together, aiFord no p 

'providei! the salts be pure J. 

Baryies is usually found native contbtncd with tdi 
Init It occun sometimes tiflitRl to silica ( aitd ibc ti 
j«/j/c, which is a n-;insparnii crrsntlized stone, i 
componnd -of silica, alumina, and barjrtes. ' ' 

4- SWotitim resemblra baryies exactly iti id'aSoiii 



I Dntieq, IbW/iiI. J; Chtncri* n 

tfcl. 



t Morwan, tWd. ai 



^HBitu-lbs. It 
Imtt alumina and sili< 

It sliowa no tendency 
is its affinity for alumina strong 



COMBIKATtONS OP EARTHS. 



precisely in the same way 

and precipitates silica from 

magnesia ; 

igh to occasion 



s of stroHliao and alumi- 
It shows no tendency to unite 



predfntate when the in 

B Mte mixed together 

itb buy tea. > 

Stroniian always occurs native combined with addfj' 

t least it has never yet been found united to eantn. ■"• 
5. Like the other alkaline earths, lime lits a strong 3' 
mffinity for alumina and silica. Scheele fir« observed, 
ibat when alumina is mixed with lime-water, tt com- 
li)iie& with the lime, and leaves the w&rer in a slate of 
purity*. The compound thus formed is insoluble in 
water. Chenevix has shown, thai this affinity be. 
twceti lime and alumina facilitates the solution of lime 
io a fixed alkali. When a solution of potash is boiled 
upon pure lime, no more of it is dissolved than would 
have beea taken up by the water alone which holds 
the potash in solution ; but when potash Is boiled in a 
mixture of time and alumina, thts last earth is dissol- 
ved, together with a much greater proportion of the 
lime than can be ascribed to the action of tlie water 
alone +. The affinity, however, of these two earths for 
ench other is not strong enough to occasion a precipi- 
tate when their solutions in the tame acid arc mi^ed to- 
gether. Thus no precipitate falls when muriates o(' 
lime and alumina are mixed J. nj . 

> GwloliafirUjemarkedtbat-limQ^watBr forms a pre. 



• Schtelc. i. 196. i Ptil. Tr«j. lEoi.p. 346 

t Du-ncc;, A*.d^^!iM.iJ,jg. lad Cheuerit, Ibid. 






rsaB^MBait tin 



coHatHAttoas or zax^iu. 



sn 



liiu be present, (he alltsjine otrbonate throws down Cha p. |. 
of the earlbs in combinaiign- Wtien pot»h is 
fi upon tliis compoiiBd of magnesia aod alnroiaa, 
a very email proportion of the xltimina is dissol- 
I tfae greater part being retained by i|s HJItnily for 
aagnesia. Bj dissolving tlie residuum in tnurialtc 
Mid precipiiaiing by CHrbonatc of poia&b, a por- 
of the ma^ncMa is retained in solution. Potash 
d on the residue dis»olves s new dose of alumina. 
Cfwaiing these processes alternately, the two earths 
be Separated from each other *. Thus sve see that 
Ktion of magDcsia on alumina is the rever&e of the 
n of alacnina on lime ; the last pcomoles the m^B» 
■f the b<ac, whereas the first prevents tltc soluiioA ' 
e alumina. 

agneiia, when mtxtd with silica, forms a fusible ] 
»Mind i but the mixiure of this eanh with bar^tc% 
strontiitn, with lime, or with alumina, is not fusi» 1 
1 the heats of oiur furnaces. 

agnesiA is frequently founiJ narive cotnbined viA i 
ther canh*. Thete native combittBtiaos consist 1 
limes of two earths, somecimes of three, and in gt^ 
some metallic oxide is also present. Tbej majr 
itnprcfacndud under three classes : 

1. Alumina and magnesia, 

2. Silica and magnesia, 

3. Silica, alumina, add magnesia. 
M first of these classes bckings the ruity ; to the 

B third, I 



1 iifiii/Jt, 



: tj/amtt 



t Sttttssure. A toapf feel, and a ccrtaift 



■ CheOCvil «n Cr-v..', 



SZCAMDaRY COHPOdKDS. 

dc^rte o(«ofntFS< ftndopaciij, has been cooudendut I 
charactnistic 6( the earthy combmationt which o 
nw^esia; but the roby and cyanitc are both of dm J 
tTHiparcnt and hard. It is u-orthr of atlenttoD, Ihs 1 
mBgnena ctitcrt inio fcnrer fiuible compounds ttiio Uf 1 
of (be alkalinf earths. 

1. Alninma; at has been already renuuked, li* I 
an affinity for ail tti« BikaliiM: earths. It hat aboit I 
affinity for silica. When silicated and alutninated pc^ J 
xA are tnixcd tofcthrr, the mixure in about an I 
becomo opaqoc and gelatinous, evidently in ctn 
qtience of the cotnbinstion «)f Uie two earths *. Wbe 
■his [nvcipitaic ii dried and analysed, it yields b 
lies and alucoina. The prcieuce of alumina, ai 1 
CFicnrvix hxi remarked, facilitates the solution ofnl 
in poiath. When a mineral containiog both s 
almntna is fused ia the usual way with a i 
qoantily of potash. »nd then dissolved in muri 
a number of white jlakes frcqacntly remain^ 1 
acid U incapable af dissolving. Theve wttici 
fiurc siliceous earth. Their quantity is gn 
the proportion of the silica over the aluaiin 
When the proponioa of alumina is considi 
insoluble residue is less, and in some cases it d 
altogether t. 

Alumina enters imo fusion witll none of tlie i 
earths except lime, and not even with the fixed a 
If this respect it differs exceedingly from silica j whi^ 
^mtlie oumcTous fusible compounds that it i 
blc ol Eorming, was formerly called ihc vitrifiabUu 



1, Ann, A C^>ii.xui.S4l. -(KiJ. i 



reOIiBWATKWS or BaRTBS. 
Bat alumina enters inlo several triple earthy mixtures 
which are fusible. Thus mixluies of alumina and si- 
lica with any of the alkilitie earths, and with magnesia, 

* «rc fusible. 

* Alumina is found native in great abundance, and al- 
' most always combined with other earths or with me- 

^ tallic oxides, for which it has a very strong afHnily. 

% Tbe native earthy combinaiions, of which it consti- 

h tatet an ingredient, may be divided into !.ix classes. 

\ These are, 

I* I. Alumina and magnesia, 

l!| 2. Alumina and silica, 

B3. Alumina, silica, and barytcs, 
4. Alumina, silica, and lime, 
I ' 5. Alumina, silica, and magnesia, 

I 6. Alumina, silica, and glucina. 

I To Uie first of these classes belongs the rvi^ ; to the 
I MCOnd, mica, chalcedony, &i.c. ; to the third, itaurolile ,- 
to the fourth, zeolites ; to the fifth, cyaaile ; and to the 
sixtb, tlie emerald. These minerals will be described 
hereafter. All the compounds idio which a consider- 
able portion of alumina enters are pretty heavy, and se- 
veral of them are exceedingly hard. 

, Silica, as wc have &etn, has an afGnity for the al- ^ 
luline earths and alumina. It has likewise an affinity 
fonirconia. When a mixture of this last earth and 
silica is l.eated strongly, it shows a tendency to fusion ". 
It fuses, as wc have seen already, with barytes, stron- 
lian, lime, and magnesia ; so that alumina is the only 
«arth hitherto tried with which it does not enter into 



tECOMDAXr COMtOVSjn. 

Silica is found native more abundantljr tfata taji 
the other earths. It alio enten into s grcuet v 
of combinations, but almo&t always with eatihy 
The combitiiktioQi of which it is known to conttitBic |J 
fkrl may be reduced under eight cUmcs i nvncljr, 

1. Silica and alumtna, 
3. Silica and lii&e, 

3. Silica and magneaia, 

4. Silica and lirconia, 
.S. Silica, alamtna. and Itme, 
6. Silica, alnmina, and magnetii, 
1. Silica, atumina, and glucina, 
8. Silica, alumina, and barylc). 

All of these classes have been mentioned alrcadj, uj 
instances given of minerals belonging to och, ctcrpt 

L the fourth, to which belong only the mrcou ud ilic If. 
acintb. 

The most bcauliful »nhy combinations are ihox 

I which Gontitt cKirQy of silica and aluminB. To dm 
clajs belong almosL all ibe gems. The combioaiioilief 

I tllcse VM9 carrhs are also the most useful ; for they aiD> 
•tiiuie the basis of porcelain, stoneware, glass pots, lai 

I all iha difSerent earthen uIcumU. 

g. Several of the earths are capable of cotDbinii^ 

- KIcewise with mvtallJc oxides^ and of forming conk 
pounds ; the nature of which has scarcely been usmi. 
ncd by chemists. All the oxides wliich fuse rcuiilj 
into a glass arc capable, in that state, of combiiunjj 
with earths by the assisiaace of beat, and of forming 
opatjue compounds, known by the ntimc of tmituii, 
some of which wiU come uiider our coosidcratioQ ii- 
tnwaids. 



COHSIHATIO^fS at ZA8THS. 



Hind 



only six metals in the sia 
nitive combined with ear 



; of oxides have 
IS. These arc, 



1. ChrotniufDj 

2. Nickel, 

3. Copper, 
Chromium cunsiitu 

latter of ilic raiy, in 
hin> and magnesia ; 
any remarkable 



but 



4. Zinci 

5. Manganese, 

6. Iron. 

very frccjutnily the colouring i 
hich it is combined with alu. 
metal does not appear to 
idencjr to combine with earths 



izcept when it is in the state ef an acid< 

Nickel has been detected by Klaproih to the chrjso- i. Nitkct 
fctisc, and in tlie green mailer called pimelite which 
Dmetimes accocnpantes it; but whether the combina. 
ion is chemical, or merelj a mixture, has not been as- 
^riained. 

The oside of copjwr shows no pecnliar tendency to 3 Copper. 
jnite with earths, and hitherto it has been detected in 
ne earthy compoand only ; namely, the smara^ditc, a 
lineral which contains Vb pti cttil. of oxide of copper. 
lUt whether thii oxide be chemically combined or 
Krely mixed with the other ingredients is not known. 
The oxide of zinc has been found native combined <■ ^<'^- 
riih silica in diffirreni varieties of calamine. That 
lliese bodies are chemically combined has been demon- 
led by Mr Smithson in his valuable paper on cala- 
nines*. 
It has been found likewise combined with alumina in 
lingular mineral latrly analvstd by Eketerg, to which 
: has given the name oi atitomelitt. This mineral ii 
\£ a dark green colour, crystallized in ottulMdront 



1 



♦»« 




^,M««*|^ 



4' Iron. 




Bttt it U m ilic oKJide* 
cbllf flic Utter, tbji tl«r 
rrMi^llic axi<dcf it OBOit 
man^aoeMT <KCifr% nathre 
ft u tttttallj a ooottitMSt cf 
Imircd 9tofft«'«t m /rfar/^ 
nrd with ear«h«, sf we except 
caiMH Kitherto obicrved, a Tery 
co'iifK)iind. 

The oxide of iron it one of 
tuei.tt of mineraU. It it f'jund in a 
ttoti with alm^Ht tvtxy earth. To h 
Cb«e«^ it the colour of minerals to be 
i««« than Mrvftn dtttinct coloarf, besMles a 
of %h tdcti, ;irc observed in mi 
aiid to the irori in mott ca^es if the coloor 
Wd. 'I'hrne colours 'are, 

1. White The somcnite, &c, 

2. Bittck Obsidian 




to 



4> Gehleo't /i/i^r. v. 442 



eoMBiNATiowa or earths. 333 

recti. Euclase, Ihallitc Chap. |. 

Blue ....Lazuliie, native prusstan blue 

Gamci, tub; 

EcUow...... .....Topaz 

Bfown Tourmaline 

experiments of Kirwan*, we learn that 
fusible mass when raized with barytes, 
tiiinina, and silica^ when it exceeds ihe propor- 
B of earih considerably. Wiih magneiiia it forms au 
mel, but scarcely fuses completely. li renders a 
Utyv of alumina and silica fusible at a very low heal 
■ in the proper proportion. 
, During ihe fusion of several mixtures or coinbi- Einhy 
of earths, especially those which are found na- 'ZSx^ 
:, the mixture very often froihes considerabh, and fi'*i q"- 
bta a great number of atr bubbles. The emission of 
ke air bubbles can only be referred to one or oiher of 
we causes, iilither a quantity of ivatcr leaves the 
Otture in the form of steam, or the mccaliic oxides, 
lich are almost always prrscni, arc reduced, and al- 
fi iheir oxygen (o escape in the form of gas ; or, 
Hy, the earths ihemselvcs undergo some change, 
i let go a portion of ihcir oxygen in the form 
^as. It is probable that the phenomenoa is part- 
Wwing to all ihesc causes ; for these earthy mixtures 
t much Itghier after having been exposed to the ac' 
e of the hre than they were before. Thus a mix- 
't of equal parts of silica and magnesia, after b'llng 
■ied to 134° Wedgewodd, lost 0-i35 of its weight ; 
d a mixture ot equal parts of alumina and barytet 



L 



k 



tECoxDAJLT comocnt. 

loti in the same lituatioo 0'S15 et its — jgkt*. 
so grot a lost ai ibis cannot be aacriied I* a 
cause than t)ie evapomrioa of water. 

Again, several mmerals whicb are c a to w ti^ym 

tallic oxide become [ranspareni wl 

violent beat ) a cbangs which matt W i 

the revival or dtisipalion of the m«tal. Tlku ii 

case, for inMatice, with the brown obstdiaa lavarfOi 

lomieu, with the lazuliir, and with s^iorl t. Naaj| 

is escerJingly itifTicult to free ibc earth co^plci 

all mttalltc bodies t cipecijit^ alaaiina. iltt mdi ■ 

remarkable for giving the propenj of frothily taa 

mixtures. 

Concerning the third caute of the frothing af ■ 
rals, nimelv, the decompouiion of the i 
selves, nothing like preciMon could be rxpi 
component parts of the earths were discovi 
boldt annotinred some lime ago. thai the e 
property of absorbing oxygen frotn the aim 
that case the frothing might, in some insniK 
he aicribod to the emisiion of this oxygen a 
cation of heat ; btit the experiments of HuiDboI<It hi 
been trie<I without succt-ss by Saus^urc, Fabroni, Cbi 
py, Bei'lhollct, anA Delameiherie |. He h^ latj 
however, announced that be has repeated his expc 
ments succcwfully in concert with Gay-LaiHc; 1 
even declares liis belief that earths are capable of tx 
bustion as welt as other bodies^. Mr Humboldt b 
|]ol yet publislied a detailed account of tbcae ianerd 



1 ther 



* Mamm, Jtur • 
t S.^uwiri, /ht. a 



r£nj, Ftiju-Uiifwt^ t Si. 306. 

FUy. x\i, 16. f !lii.L In, i». 



COHfilNATIOKS or EARTtlS. 

irttnenis ; of course, we are ignorant of the way in 

■•h'ch (hey were performed, and of the degree of pro- 

t Wbiliiy which i hey give to his opinion; an Dpiiiion 

^ concerning which it would be unfair to decide without 

^ &nher evidence. 

^ We now know froai the discoveries of Mr Davy, 
^ tb»t the bases of tht alkaline earths are very coinbusti- 
i^ ble metals. These earths of courK are products of 
k* combustion, and tberefofe incombustible. If Mr Hum- 
m WIdi's opinion referred !o the bases of iliese earthy bo- 
ttt. ^s> It was correct ; but if it refef red to <hc earths them- 
ll aelves, it was erroneous. 

11. There Jsanoihcr pbenotnenon reelecting the fu- 
|( ston of earthy combinaliotra which has not been hither- 



to explained. Some nunerals, when exfosed to the hc- 
tian of lieai, meli very readily, and generally with a 
g«od deal of frothing ; but if the heat be continued, 
they soon become solid again, and do not fuse unless 
the temperature be considerably augmenled. This is 
Ktie case with friLniu, thallile, ai)d iotne Je/jfiart. Thus 
the prehnitc undergoes iis first fusion at 21" Wedge* 
wood, its second not till it be heated to 81^ *. It can. 
not be doubted that in this case some one or other of 
the ingredients which contributed to the first fusitm 
miut be driven ofF^ especially as the mioeral after fu- 
sion loses entirely its oiiginal appearance and proper- 
lies. The late important experiaienls of Sir James Hall 
on the exposiure of carbonate of lime to strong heats, 
under such a pressure as prevents the escape of the car- 
bonic acid, have shown that this substance, under these 



* SauMurc, /(vr. ir Fiji, iIt. 14. 



bU futiao. 




lECOHOAKT coMroosoc. 

circumstincTS acts the pan of a Sux, xnd caBtiitetm 
the fusion of the carbooatc of lime, wbidi he ben. 
complislied in a gnu Tariei; of mataaco. It i 
not be surprising if the first fiiaioa of the snfittt 
owing to the picscnce of carbr^nic acid, -and the fiKJia 
to (he escape of thxl substance. This conjecture Mm 
to hive struck Sir Jatnts Hall, n-hosc skill inUuififc. 
cult department of chemical investigation iviil nodn 
enable him in a short lime to confirm or refute i". 

12. A change no les< ciirions is producrd on tlMtp>^ 
pesrancc and faMbitilf of some miners)* bj the il 
ness or rapidity with which itiey are cooled after b 
subjected lo fusion, Whinstooe {grtenrtom ofWs, 
ncr), for instance, is a mineral which faces when r 
to a lemperatore between 40'' and Sb" Wcd^woodi 
If it be allowed after fkision fo cool rapidij, it is n 
veiled into a dark-colouitd gloss much more fod 
than the original whinstone ; but if it be made to c 
very slowly, it assumes an appenmncc which faaisoH 
resemblance (o tlie original whinstone. In this si 
is much less fusible than the glass. Sir James Hall, th 
dKcovcrer of ihis curtous fact, lias given the whin ii 
this la'l state ihe name oi tryilallitt, a term suggc«[<4 
by Dr Hope. Thu« ihe lock on which Ediabnigl 
Gasile is buitt fusts at the lempmiure of 45° Wedge 
wood. By rapid coaling it it convened inla a gian 
which melts at 22" ; by slow cooling into a eryitai 
which melts at gS". The whin of Salisbury Craig &u 
ses at 55" ; its glass at 24" ; m crystallite at 5B^' 
Lavas agree with these tniaerals in' this rc»pwt. Tbt 




CcHiSIHAtlom OF CAHTRS; 



53T 



wing Tabic eztiibits the degree cjf Wedgewood's 
meter at which the rocks tried by Sir James Hall 
rgo fusion in their natural state, in the state of glass, 
in the state of crystallite *. 



Chap. t. , 



Substances. 



in of Bell's Mills quarry, 

greenstone), •••••••• 

in of Edinburgh Castle, (por- 

hyry slate), 

umns, Arthur Seat, (gr. stone), 
liu near Duddingston Loch, 

greenstone), • 

kin of Salisbury Craigs, (ditto), 
lin from Water of Leith, 

ditto), • 

kin of StafTa, (porphyry slate), 

'a of Catania, ••••••••••• ••• 

'z of Santa Venere, Piedi- 

nonte, % 

ra of La Motta, 

ra of Iceland, 

^a of Torre del Greco, 

ra of Vesuvius, 1785, 



Original 
Scace. 



40* 

45 
55 

43 
55 

55 
38 

33 

32 
36 
35 
40 
18 



qlass. 



15^ 

22 
18 

24 
24 

16 

14i. 

18 

18 
18 
15 
18 
18 



i^mi. 



Crystal-] 
lite. 



32' 

35 
85 

38 
38 

37 
35 

38 

36 

^56 

43^ 

28 

3^. 



• 



!r James Hall has ascertained, that the crystalliza* 
of these bodies depends upon the length of time 
' are allowed to remain in a higher temperature 
I that in which the vitreous fusion takes place. A 
ute or two is stifEci^nt to induce the change ; but it 
lore complete the higher the temperature is above 
point of vitreous fusion while the crystals are form- 



* >5y»>. Trans, v. 75. 



SCCOHDAKT COHrOOVD*. 



\l 



, ■•( i provided always it be not to high u t« ptiot 

■ dM crjrtnlt from shooting. 

The uriking difference in the fusibilitj oi ihcitk. 
liin secmi lo dcpeitd upon the war in wbtch i^ cnn. 
poneni part* of the rriitierji are corabtocd. Wbenod. 
ed rapid!}', these component parts have not time t«i 
bine according Co lti«tr AlTiiiiiics bof^rc huddled mt- 
gvlarly together. Ot course the lorce of the 
of those component parts which have • tendencjU ens* 
bine, must conspire with the actioo of the fire to 
the cohesion of the pacts ; the conseqaencc of »Uh' 
mnst be I'auon. Whereas in the crj^iaUite, lbeco»i 
poncnt pans having had lime to oombitw •coordjag' 
tbeir aSiiitics, instead of conspiring with the divcilat 
action of the fire, npjiose it by coinciding with the km 
of cohesion. In the fir&t case two forces 
prodoce fusion ; in the seciwid, onl^ one. 
aimiUr to this m»y perhaps take place in those 
which undergo a double fusion, the itrU in a lover 
than the second *. 



• Upa)iM(iub)<rirlic ' -' - j Ii ■ iiiiriiH|ii|iii Iji1j1| 

Mr Gntfoi} Win. »h(»c ptcm^riire dcuh mnt be dccfif rtgrmj[ 
(k( luliirtion nf chcmicit Ki'ni& Hffnxfj about wven brndi 
algnait'^t Ji t futOKt, dllowrd ii co (■«! ■Ivwff . au.. ihcn 
iU nriou daagct it bsJ unjcrg^nc Sk tii/, Tmt, llo«. 



or STONEWARZ. 

■C dislingaishing ctiaracter of alumina ia la contrnct 
bulk, and to acquire the hardness and solidity of a 
mj bod;, if it be made up into a paste with water, 
icd slowljr in the open air, and then exposed to the 
-ong heat of a furnace. It communicates this proper- Pr 
to the numerous tribe of clayi, which arc so com- 
oo in most countries; a propertj* which has doubt- 
is suggested the applying of clays to form various 
ssels and other bodies for the purposes of the arts and 
domestic economy. Claysconsist essentially of alu- 
iaa and silica mixed in various proportions i and iaieJ 
>y, of course, must be considered as a compound of 
CM two earths. We shall, in the present Section, take 
ihort view of the manufacture of the various substan- 
■ formed of baked clay. As there is no single term 
our language which comprehends all these bodies, 1 
ive givtrn to the Section the title of itoniviart, which 
dudes the greater number of them. These bodies 
ay be divided into four sets; namely, bt-idi and tiiet, 
ti anA emcibiei, ttoneware and porceiaiM. A detailed qj^, 
count of the manufacture of these bodies would be 
iproper in this place, and is not intended ; such ■ 
etch only is meant as may lead the reader lo the prin- 
a of the art. 




$40 %ttow%AU comfmaw 

BookH. 
IH^UionTir. I^ BaiCKS AKD Tfl-TS. 



Bricks are oblong masses of baked claj, used ait 
substitute for stones in buildings aod iUes are prepared 
for covering ttie roofs of houses. The ase of them maj 
be dated from the roost remote antiquity ; and wfaea 
properly prepared, thej are little inferior in dorahilitf 
to ston J bodies themselves. Manj anrirt oMioiiiBcnts 
t built of brick still remain entire. 
Tbc cby. Bricks are prepared from the eommoa Use d^, 
which occurs in abundance in aloiost all coontries. It 
coght to be of such a natore as not to be liaUe to &• 
sion when exposed to a strong heat ) si leasl if ths 
bricks arc intended to withstand the action of fire. The 
presence of a portion of lime rcodera elnjr fnsiUe. If 
the claj contains too little sand, the bricks are liahb 
to crack in cooling ; too much, on the other haad, pre* 
vents the proper degree of cohesion. Henoe the good- 
ness of the bricks depends upon the daj of which the/ 
are made, which can only be ascertained bj experience. 
It depends also upon the degree of heat employed in ba- 
king them. When not sufficiently burned, they are li- 
able to crumble down in a very short time. 
jIj^ f^^. The clay is dug out of the earth, and after being ex- 

XH'^S* posed for some time to the air is reduced to powder, 
and foTired into a paste with water. The bricks are 
then formed in moulds;, exposed for some time to dry in 
the open uir, and than burnt in a large furnace con- 
structed on piirpobc. Tiles are formed in the same way. 
The clay, however^ is fiiier, and it is usually ground io 
ii mill. Britks and tiies shoiild he impervious to water: 
They sliouKl be capable of withstanding the actioo 



y 



nOHKWASE. 



541 



, 2nd not be subject to moulder. The clay of Chap. I. 
Sch these substances are made always contains iron ; " 

aice the red colour which they acquire in buining. 



II. Pots akd Crucidles. 

For various manufactures it is necessary to have 
vessels capable of resisting very violent heals without 
fiiuon, even when in contact with bodies that act the 
part of fluxes. This is the case for instance in glait 
mating, and in the smelling of the ores of tlie difficult- 
ly fusible metals, as iron and copper. The glasshouse 
pots arc formed of the purest kinds of clay that can be 
procured. By pure clay is meant a clay free from lime, 
wid from any great proportion of iron. Stnrbridge clay 
is compionly used for the purpose in this country. To 
prevent it firom coniraciing too much in bulk when heal- 
ed, it is mixed with a proper proportion of old pots re- 
duced to powder. The pots are baked in a mould with 
great atieniion, and afterwards allowed to dry as slowly 
2s possible. They are afterwards baked in the requi- 
aile degree of heat. 

The crucibles used for chemical purposes are pre- Cmciblct. 
pared of similar materials. Sometimes sand is usird in- 
stead of nld crucibles; si'mcriimcs plumbago is substi- 
tuted. The crucibles are then caljed hlacJs lead cru- 
cibles •. 



* For 1 rietailed account Dfcmcibleiaitfi cUy riirriica, ih« reader it 

nterrcdtn Bjumc't ClvMum, iii. ilj.. The ben aC(..vnL or;%'«i(> Tm 

; chemical piirpoKt which h« hilhrr.D ipprare.l in ih' Engl'nh language, 

t» (H»a> byl^f Lewifit ihi beglnnmyof h'! PW-^phital C'lmirti '/Ih 

-j#ft. Piacticil chemiKi wiU do veII to coiuult ilul imporcvit ireitlK. 



, ^id w^ p — fcafclj cauricid on ■% I 




1. Hm body oC the vomI callcti ibe iittvit. i. IV 
g*>W7 «**«™^ •** which it n coated ctlMtk 

Thcbbcuitn ceinpoaM of two ingretKentt i Ac fa 
is ft fine white cUy, kaown bj the namei of nAan, 
fipt rtay Md ^"^ tl»Jw »nd th« »econd a Sac while 
tand. !n thi> coontrj the sand is precarcd by cala- 
nlng flints lo whiteoes*, u»d griadiog ibem io ■ miE 
The gUte conjim of Tsriou lagTrdlents according i» 
circuTDiUnces. We sh«U first t»ke s rtew of the pre- 
paration of ihe biscuit, aod iben of the glaze. 
t Staffordstirc is the coaniy in which the grwtni 
quantiiy of stoneware is made ut Britain- Hence it it 
often calUd Siajbrdihire wart. The clay employed in 
the manufactures is brought from Dorset and Defoa- 
thire, and ihc Hints fiotn the south-eastern couDtlu. 
Th< clay U ndoced nearly to the conustence ef'mi^ 



STOHEWARE. 



549 



I water, and ihe liquid pasKd ihrough lawn sieves Chap. I. ^ 
lually increanng in fineness. By tl)<^ aieans all 
coarse sand is Kparated, and only the minutes) par- 
's of the clay left suspended in the water. The flint, 
riously graund lo a very line powder between mill- 
es of chert (honistone), is mixed with waler se- 
tiely, and brought to th< consiil<rnce of crearD. 
;sc two liquids cnnlaining the clay and the flint are 
<d together in various proportions according to 
nmstancet; the flint liquor, in some cases, amount- 
to ^th) in others to ^ih of the whole. The mixed 
id, after being well stirred, is let into traugbs, and 
poraled to the proper consistence. This mixture ii 
) taken out, and kneaded into a fine dough. This 
1 of ibe process is tedious, but essential ; as it is ■<• 
ary that the whole should be equally mixed, and of 

same consistence. The dough thus prepared, W 
>t for us« in daotp vaults ; from which it is taken ■« J 
uioa requires, aud given lo the workmen, w 
did it on the lath lo the proper shape. The vessel* , 
s rudely formed are in good wesiUer dried in tha I 
n air ; but in bad weather, in sIotcs healed for th* ' 
pose. When sufficiently dry to bear it, ihey ar« 
■ied back again to the lath to have their a^writiea 
en off, and the exact shape given. They are then 
iwed to dry as completely as possible. Afterwards 
•f are put into cylindrical earthen vessels, formed of 
indcd fire-bricks and clay, called leggars ; and when 

shape will admit, each seg(>ar is filled with the ves- 
i to be baked, laid one above another. These seg- 
E are piled one above another tn a large circular 
1 capable of holding a considtrable number. When 
seggars are put in, the door of the kiln Is built up 



IZCOVSART CC 

with bricks, and plaatered ovi 
> of furnaces built rouod the ki 
to the middle of it, are then li 
kiln and its content* to a very 
fire i( kept up for 4S hours, ai 
Tlie veSBcli, when taken out 
iisemit. They reicmble a tol 
ud like it absorb water with 
be employed coromodiously, * 
ij, till their surface is covem 
The glavr employed to c< 
may be diiiingui^hcd into thr< 
or sulphuret of lead, eotnmon i 
* Catena is employed only t< 
sest kinds of stoneware. Wl 
and exposed to the proper tei 
diuipated, and the lead oxid 
strong tendency to vitrefy, anc 
earthy bodies. The brown g 
ware, then, is nothing else thar 
aels aie dangrrous when used ( 
as the glaic is easily corrodec 
and various saline bodies. 
n Common iiult i&cmployed t( 
stoneware vesseU. The proi 
the biscuit is suflicienily bake 
IaU is introduced into t)ie k 
this salt into a vapourj iipcne 
hulei left on purpose, aud surr 
amiosphiTL' <it salr. The salt 
surt'^ice ot itie biscuit, disposes 
Enamel is notliing else tliiii 
over the surface of the biscuit 



c\ 



8t()!*EllrAltE.- 



iii 



various proporiion<i of oxide of lead mixed with Ctu p.I. 
id Mid glass. Mr Wtdgewood published ihe foUow- 
ihe enamel wliicli he used : One liundred paris 
k«d arc melrtd wiih from 13 to +0 parts of tin, and 
lixiure oxidized completely, by. exposing it to heat 
open vessel. One liundred pans of this oxide are 
ixed with 1 00 parts of a fine while sand, composed of 
R pans silica and one part of lalc, and with about 
pans of common salt. This mixture is melted, then 
daced to powder, and formed into a liquid of the 
WMStcnce of cream. According to Dr Waison, the 
tllow glare used in Staffordshire is composed of 112 
irt> of while lead, 24 of ground flint, and sis of flint ' 
law, mixed with water to tlie consistence of cream*. 
fie biscuit is dipt into this liquid and drawn out again; 
f this means its surface is covtrcd wiih the sdlid mat- 
'r of the enamel, the water being speedily absorbed. 
!rHe vessels ate put into the seggars as before, but a lit- 
is of stoneware is interposed to keep them sepa^ 
jmrale. They are ptil again i^iio the kiln and heated as 
St first. The enamel melts into a glass, and spreads 
equally on their surface. The excellency of a good ena- 
mel is, thai it easily fuses into a kind of paste at the 
beat which is necessary for baking stoneware, and 
spreads equably ou the vessel, forming a smooth glassy 
•urface, without losing itsopaeiiy, or Bowing complete- 
ly into a glass. Its whiteness depends upon the prO' 
yortioD of the tin, its fusibility upon the lead f . 



i FoF an Bccounc of the manuricture el tl<incwirc, the reader maf 
ni'* ChemiKry.iii. 1:7, and Wiiaon's Cirmiial Eii'ji.it- 



••Ii,Im« Imm MxroifHiJ, M WlHt*k«f iafiiF»i », ^ ^yi 
IH itw f hHk <■( rl.i Mitum I.7MW. TV- >■■• /— i^ ■. 
WhiuhH, tnni*«ri"inili« KrcHti nnc i4 tb< five /•■i^ 
/>wif*'«, wldtbtiMtpirfU-cnknuedBawn. Ii gM tkx J 

bl '1 'VaNi •/ //mMM mr a, Jlf., lis. 



r 



STONEWARE. 



|duriiig; a set of experiments in order to ascertain the 
beat raixiUTcs for making crucibles, stumbled ii^^'on a 
compound whicli yielded a porcelain similario theEast- 
Cftu Inconsequence of this discovery, Saxony soon 
jwoducfd porcelain scarcely inferior to that of Japan in 
Msuty, and superior lo h in solidity and strength : But 
lis composition was kept secret! nor were there any 
Accurate idi;as respecting the connpiineni parts of porce- 
lain among men of science, till Reaumur published his 
lissertationson the subject in n2i and ItJQ. 

That cetebfRted philosopher cxarnined the porcelain 
•f Japan and the different imitations of it which hail 
oten produced in France ajid oiher pans oi Europe. 
The texture of the first was compact and solid, but that 
of the imitations was porous. When both were expo- 
sed to a strong heat, the first remained unaltered, but 
Hlc others melted into glasi. From these experiments 
lie drew the following ingenious conclusions- 
Porcelain owes its semitransparency to a kind of se- 
ffiiviirificalioti which it has undergone. Now it may 
;receive this two ways; 1. Its component parts may 
'%e such as easily vitrify when suflicienlly heated ; but 
itlie degree of heat given may be just sufficient to occa- 
Ision a commencement of vitrification. This parc*.Uia 
when Mrunijly healed will easily melt. Such, thtrc 
.(ore, was the composition of the European imiiaiions 
{of porcelain. 2. It may be composed of two ingre- 
'dienis I one of which vitrifies, but the other is not aU 
tered by beat. When a porcelain composed of such 
materials is baked in a suflicient heat, ibe fusible part 
imelf, e;riveiopes the infusible, and forms a semitranspa. 
siibstanc,-, v hich is not fariher alieicd hy the i.;mc 
tgree of heat. Such ilieit <bre must be the porcelaia 
M m 3 





COMBIVATIONS OF EARTm. 

of Japan. Father Entrecolles, a miuionary le Chioi^ 
had sent an account of the Chinese mode of n)akinj[p«. 
c«lain, which coincided exactly with ihis ingcniou 
thought of Kcaumur. The ingredients, according lo 
liiin, are a hard stone called pttuntt, which they grind 
to powder.and a white earth called AtioUn, which iiin. 
timatcly mixed with it. Reaumur found the peiiinieb> 
sible, and the kaolin iufusible, when exposed WJ 
to a violent heat. 

These notions were not pro»ecnled farther by R< 
mur ; but in 1158, the Count de Laursgais, astiited by; 
l)arcet and he Gay, began a lel of cxpertmenit nhi( 
were continued for four year*, and which led lo tl 
discovery of a porcelain pos^esied of the aaiuc <)ual!d 
with that of China, and inferior only in whiieneib 
Macqiicr, who at that lime tuperin tended l>»e manufi 
tory of Sevres, advised the French government to pn» 
pose a reward for the dJMOvcry of earthy substances 
pableoffotminp awhile porcelain. This was done [ 
and in consci]cncc of it, VilUris, an apothecary of Bone 
deaus, announced the existence of a while caitb 
Saint-Yriexla Perchc, in the department of llie Haolt 
Vicnne, which in his opinion would answer the pnrpoWf 
■. It was tried br Macquer with the expected &ucce-s. , 
porcelain manufaciory was established at Sevres, ti 
at present there arc no fewer than 30 in France". Dj 
fcrcnt manufactures of porcelain have been successfvlh 
established likewise in England ; first at Chelsea in 
neighbourhood of Lnndou, and afterwards in Coalbrook 
dale, and in Derby. 



,T III Onri-ri A Terrt, aifi, f. 7*^ 



STONEWARE* 54t 

'^ The essential ingredient of porcelain is a very pure Chap. L ^ 
''^ claj known by the name oi porcelain clay. This is Poi eiatn 
"- equivalent to the kaolin of the Chinese. Macquer **' 
^ and Baume, in the course of their experiments, ascer-> 
^ tained that very fine porcelain may be made hy using 
''^: the earth of alum instead of clay; but the great ex- 
^^^. pence prevents the possibility of introducing it into the 
Qt manufacture of that article with advantage. Sometimes 
porcelain clay consists of materials mixed In such pro- 
^ portions that no addition is necessary ; the biscuit made 
from it being susceptible of undergoing that semivitrifi- 
cation which gives the transparency and compact nature 
i¥hich distinguish porcelain. Such is the porcelain 
day of Limoges. According to the analysis of Hasseu- 
fratZy it is composed of 62 silica 

IP alumina 

12 magnesia 

7 barytes 



100 



The porcelaintiay of Cornwall, which does not acquire 
transparency without addition, yielded to Mr Wedge* 
wood «.60 alumina 

20 silica 

12 moisture 
8 loss 

loot 



^JUw. d€ Cbim. xiv. 144. f Kifwan'f V.h, i. 1 79. 



COUBTNATIOKS OF EAKTMS. 

Giebert lias announced that porcclaia euth it lont. 
ttcnc* nearly pure magnesia and ailica t- 

Wh«n an addition is ncccMnfiTr tlic itibstanct mri'a 
J<lspar, which is equivalent to the pelDntC oftbeCtii. 
ncic. Accoiding loan aoun^Dioua German wriw, the 
finMt Saxon porcelain is formed by mixing togttlitr 
equal u'ciglils cT ground felspar and porcelain tU)}, 
Tile tncihod of forming the biscuit of pnrcelam u iht 
Skmc a') of sioneware, and therefore requires no pwi- 
culai descripiion. 

Porcelain is always covered with a glaze, eompoKJ 
of earth« ingrcdienis without any mixiure of nitutk 
oxides. Hence the high lemperaiiirc nccetsary to fue 
it, and tlie property which pomlain vessels have si n. 
aiariug the uctiunof iht moM corrosive ra b& lancet pn- 
cisely a> common glass does. The substance comoni. 
ly employed \\ ftUpar ,- which is composed cuentiallf 
of silica and aluniitia united (o some potash, to nrhidl 
, the fusibility is to be ascribed, Thia is the glaze mi 
I to be used in Saxony, and, as Brogniari informi u, 
likewise ai the manufactory of Sevres, near Paris. 

Vessels both of stoneware and porcelain ale earn- 
monly painted of various colours. Tb«»e paintingtm 
often excellcni, both inelegance of workmanship aiidti 
brilliancy of colours. The colours are given by metu 
of metallic oxides, which are mixed up with other in- 
gredienis proper to constitute aa enatDcl, and apnJiedin 
the usual manner with a pencil. 



i if.<« A ' r.,M .■..<rf..«, 4c. p. tog. It the end of the Fiw* 
trantUtioD of N'cr.'i ^n ef GVnniraJuij. 



V 




. STOKEWAltS* 

On this subject much light has been thrown by the 
^experiments of Wedgewood ; and Brogniart has latelj 
{inblished a general account of the processes at Sevres, 
of which he is director *. ^ 

The process differs a little according to the substance 
on which the colours are to be applied. When the ves- 
sels are covered with enamel, less flux is necessar j, be«* . 
cause the enamel melts at si low heat, and the colours 
readily incorporate with it. But this rendets them 
more dilute, and makes it often necessary to retouch 
them* The colours on enamel generally appear bril- 
liant and softy and are not liable to scale. The flux is 
cither a glass of flint and lead, or borax mixed with 
flint glass* The colours are usually made into a paste 
by means of gum water or volatile oils. Some of them 
are liable to alteration by the action of the lead on 
them. 

The colours applied upon hard porcelain, or porcc- pointing on 
lain glazed with felspar, are nearly the same as those ap. r^^^****"- 
plied on enamel, but more flux is necessary. They 
are not liable to dilution, as the felspar glaze does not 
melt at the heat requisite for fusing the colours and 
their flux. They are liable to scale oflT when repeated- 
ly heated. 

Colours are sometimes applied over the whole surface 
of the porcelain ; the flux in that case is felspar. 
But such colours are not numerous, because few oxides 
can stand the heat necessary for melting felspar without 
being altered or volatilized. 



* PbU. Mog. xiii. ,M^. 




P59 COMBINATIONS or EARTHS. 

)hrl?'ilr ^' '*"*'P^^ " givtn by means of the purple oxidtof 



gold precipitated bj the smallest possible qaaotitj d 
muriate of tin. This oxide is mixed with a proper qua. 
tity of powdered glass, bornx, and oxide of antimooj, 
and applied with a pencil. It cannot bear a strong bat 
without losing its colour. 

2. Red is given by oxide of iron, A mixture of tvo 
parts of sulphate of iron and one part of alum is calciixd 
slowly, till it acquires a fine red colour when cold. This 
powder is mixed with the usual flux, and applied with 
a pencil. 

3. Yellow is given by the oxide of silver, or bjox. 
ides of lead, antimony, and sand ; green, by the oxide 
pf copper ; blue, by the oxide of cobalt ; and violet, b^ 
the oxide of manganese. 

For farther information on this subject, the reader is 
referred to the dissertation of Brogniart. 

Gi-lding upon porcelain is performed in the samewaj 
as painting. The gold is reduced to the state of an im- 
palpable powder by solution and precipitation. It is 
mixed up to the proper consistence with oil and a small 
quantity of flux, and applied with a pencil; the vessels 
are baked a second time. By this the gold is made to 
attach itself firmly to the vessel, and by the burnisher 
it acquires tlie requisite lustre, Klaproth has latelj 
shown, that platinum may be applied upon porcelaia 
with a simii<ir eSect. The fine powder of platinum ob. 
tained by precipitating the metal by means of sal am* 
moniac, and exposing the precipitate to a red heat, is to 
be ground with a little flux and oil to the proper consist, 
ence. and applied will) a pencil upon the vessels. By 



STOKE WARE. 



K these vessels and burnishing, tlie platinum ac- 
thc requiiiite lustre *. 
A aiiiting common stoneware vessels would enhance i 
their price loo much ; but this is avoided by an ingeni- I 
BUS mode of copperplaie-prinling, said to have been first 
iavented by some person in the neighbourhood ot' Liver- 
pool. The figure which is to be paiined on ihe vessel 
is engraven on a cogj^erplaie in the usual way, except- 
ing only that it is not reversed as is done iu common 
copperplate-engraving. The paint to be applied to the 
Stoneware is brought to the requisite conMslence, put 
upon the copperplate, and the impression taken off, 
U usual, upon moist paper, by means of the roll- 
ing press. The paper, ivhile still moist, is apphed to 
(he stoneware biscuit and pressed upon it. By dipping 
Ihe biscuit in water and agitating gently, the paper is 
washed off without injuring the impression upon the 
vessel, the paini having been made up with oil. The 
impression upon the paper was reversed, but upon the 
stoneware it is precisely rs it was cut upon the cop- 
perplate. The vessel being now baked, the paint is 
slazcd on, and assumes its characieribtic colmr and 
brilliancy. By this contrivance any number of vessels 
may be easily printed with the same figures in a very 
short lime. This ingenious process seems to be at pre- 
sent confined to Britain ; at least none of the foreign 
stoneware that I have had an opportunity of examining, 
exhibited any marks of having been primed. Neither 
has any mention of the process been inserted ioto any 
work which I have met with. 




§M GomnrATmirt or BAftxn. 

The tpecifie gmvitj of the different kinds of tm. 
•ware diffen considerably noodnling to the comptctiQ 
of the texture. The followiog are the reioitt obtamc 
bj Dr Watson ^ and Brisson : 

East Indian Chinaf 8' 385 

East Indian China t S*34G 

LimOges porcelainf 2*341 

Bristol stoneware t ••••• 2-340 

PUntwaret « 2-lSft 

Sevres porcelainf 2*140 

Yellow ware t 1'0S8 

efliwlnlJ[«»y,a.si*> tBrimn. |1 



CHAP. II. 
OF GLASS. 



lA, when mixed with the fixed allcklief, and ex- 
to a strong heat, enters readilj into fusion. It 
melis aha wh«n heated along with some of the alkaline 
earths, especially lime, provided a little alumina be pre- 
Kni. These mixtures arc very ductile while in fusion, 
and may be readily moulded into any shape we please. 
If they be suddenly cooled below the temperature at 
which they become solid, tliey retain their transparency, 
and assume those peculiar properties which belong to 
tlie substance called ^/ajj. G!aji then is acombination 
of the fixed alkalies or alkaline earths with silica, either 
alone or conjoined with alumina, brought into complete 
fusion, and then suddenly congealed. Metallic oxides 
are sometimes added : they assist the fusion like (he ■!• 
kalies, and communicate frequently a peculiar colour to 
the vitreous mass. 

The method of making glass was known at tt very . 
early period. According to Pliny, the discovery was 
owing to an accident. Some merchants, with a ship- 
load of soda from Egypt, had cast anchor at the mouth 
of the river Bclus in Phcenicia, and were dressing theJr 
dinner on the sand. They made use of large lumps of 



SECOMDART COMrOUNDS. 

soda to support tbeir kettles, -nd lighted firt» vah 
_ them. Tlie heat tneltcd the sod^t and the ultceoai a4 
together, nnd rtie result wat glau. For some UiMitB 
this accidental discovery the maniifBCturc of glti 
conRncd to the river Bclo». This mannfacmtc 
lo have been carried to a considerable degree of pa. 
fcclion among the atuicDis. They meiitioii dtinlkiw 
gUsies, glass prisms, and coloured glnsscs of vuign 
kiiidj. But |)erfECilj traniparenl glass was coniiioH 
as very valuable ; for Nero gave L. 50,(^00 for »« 
glass cups with handles ; a proof that their procma 
must have been far less perfect ttian ours. Itwasu». 
a1 for ihcm to tnell the materials of their gUuinigi 
black mass called ammomtrum, of whicli ststuet nre 
sometimes made. This amiDOnitrum was again ntlitd 
snd purified by refiners. Glass panes seem la hm 
been first used in windows in the third century, butlbej 
did not come into comttioo uu till long after *. 

While glass is in fusion, the substances which 
into its composition may be consideied as 
will) each other so as to lonii a homogeneous matt, 
milar to water, holding a variety of salts in sduticn. 
If it be cooled down very slowly, the different teadcncj 
of the coostttuencs to assume solid tuims at pecutq; 
temperatures will cause them to separate 
in crystals i jusl as the salts held in solui 
assume the form of crystals as the liquid is slowly 
evaporated. But if the glass be quickly cooled do»D 
to the point of congelation, the constituents have oat 



• See Dr Filconer'i p»pe' on thu Kibjcct, MmAtHtr M-mtn. it 
95. and Hr Mciretf'i Prcfjce to hi) Litin Trindatloii of Nafi ^i 



4 



GLASS. 557 

ne lo separate in succession, and ihe glass remains the Clui'.U.^ 
me homogeneous coinfiound as while in a Slate ol !ii- 
Od i just as would happen to a saline solution if sud- 
Mlj exposed to a cold sudicient to congeal it com- 
leielj. Hence h appears that the viireous quality de- 
( entirely upoii the fusibility of the inixiure, and 
le suddenness wl[h which it is coaled down to the 
oint of coTigelaiion. The substance, though solid, is 
rcciscly llie same as toils chemical composition aa if 
were still in fusion ; the sudden cooling having 
ted ihc constituents before they had lime to assume « 
■w arrangcmeni. 

All fusible mixtures of the earths proper with fixed 
ikailies, alkaline earths, or metallic oxides, may be » 

lade ai pleasure to assume the form of glass, or the 
|>pearance which characterises stone or porcelain, ac- 
xding to Ihc rate of cooling; and glass may be de- 
rived of its vitreous form mertly by fusing ii, and 
tooling it down with suHicieiit slowness to enable the 
instituents to separate in succession. 

Many curious experiments on this subject were 
lade by Reaumur and Lewis, who pointed out the 
mcihod of converting dilTcrent kinds of glass into an 
'opaque, white, hard, refractory substance liLe porcelain, 
which is commonly distinguished by the name of Reau- 
ftnur^i porcrlaia. Dr Lewis, by a variety of experiments, 
idemonsiraied that all kinds of glass could not be con- 
id into porcelain. He succeeded only with those 
that were composed of a variety of constituents '■ The 
iTCasod it obvious; such glasses alone contain ingredients 



• Hil- Cob. '/Ill .1<lj, p. IJO. 



Chttifia in 



tECOXDAir COMFOrVDS, 

"^^ Am become solid in tuccenion. Grt«n glm %(t^ I 

■ I *i bnt wiib him. Indeed this glsM is vny tpusb I 

^■iR « CTjriMOIizcd form. Tbc tempcnrare bwid 

m ibe rttugc i( ihat in which the glMa i; 

«M beini^ oKlted. 

It wu the corKNn cxpnimftits af Sir Junn Billa 1 
h^rfvnnd greeattooe, detailed in the precrding Ck^ I 
WT, thtt first eipLiinnl upon w)iat the viireoiit n 
wibMiBoa depends. He found thai glna (cooti«n|if I 
< M i« «* tax^j bodies) always Io«es iiN vittcom na, 
«rf tmm*am thai or a itone, if more than a mtnatt m 
fwelapwi white it is cooling down from compleuii. 
«■■ H the poini at which it congeals. 

>(^^ TWtv ate £fleTcnt kinds of glass in cooubod <att k 
Ata coaatiT for varioui purposes. The fineii utfUlt- 
gima, af which tcK>kin|;.);UKes are made, imiJ^B.^ 
auryiial, used for the fiiKSt vessels. Theie a 
fcctif trtntpareni and coloarlesi, heavy and b 
Tbev arc canpoied of fixed alkalt, pure siliceowHi 
d fliBU,andliihargv. The manufscturen comJ 
a of their ingredients with great ate*. 



encomJ 
rat OR*. 



• he the hMm atttum tt ^n-mtUmg, ike readw il idin 

SmbIw M ikc M^^jrCT pnUHtm) h} Ncri, an IiatiiB 

:o t^ijn uwirdi the end of the irtliw- 
aaj ncKr<. Kucktl itui^attd tUt !.«■ 
HUB German, and added W ibt «gri b 
« ^wnickiTK, ukI [he v-rifiuitfB «( d 
■■ «( KcfL KankrJ't work wu iracilaied into Froub, nd 
fifcitfl na^oarw voImm >b i;ji. A nry dibonte itcmi J 
^^■■mkiPlt hu becD poMiAcd *bii in the ji,i, h Mii;ft. dent if 
iBdM tlkr direttioB tJ ihr FrrDch Amlcm;. More Uttly. lanilln 
hM* oo (U»-Dukili|t ***• l"*™ wri"tn •*• Frriwh by Lofwll Tlr p>^ 
MMes u Ik dcKTibcs ibem, ditfct in nun)* rt^cii froo) (boK (iillwd 
h ikW c ustrj. 





I. 



plate glass is pouted melted upon a table covered Chip. 1L 
.f, ibeel of copper. The plate, as cast, is about an 
Jcki but it is ground down to the proper degree 
and then polished. The only manufactory 
in Britain is at St Helens, about 10 miles from Liver- 
pool. Fliiit-gla-s contains much o^fide of lead. Dr 
!wis extracted from it one-fourth ef its weight of ibat 
iBctal in a maiieable stale *. Though it be very solid, 
^itdqesnol seem lo be absoluiely impeivious to gase- 
S'OIU bodies, at li-asl when healed nearly to the melting 
^ point. Dr Lewis surrounded a piece of it with char- 
I ,COal powder, and kept it for some time in a heat not suf- 
k fident lo melt it. The lead was revived in drops 
1 tbrough the whole substance of the glass +. DrPriest- 
I«jF ascertained, that glass tubes filled with hydiogea 
^- MS, and healed, became black, from the revival of the 
t kajl. When aJkaline hydro^ulphurets are kept in glass 
i phials, the inside is soon coated with a black crust. I 
am informed by Dr Henry of Manchester, that this 
Uack crust is nothing else than lead separated by the 
sulphur from the glassi 

Crovin-glais is made without lead. It is therefore Cmva 
much lighter than flint-glass. It consists of fixed alkali ^ "" 
fused with siliceous sand. As the earthy matters em- 
ployed by the glass-makers are seldom quite pure from 
some mixture of iron or similar ingredient, the glass 
would have a green colour unlci,s some means were 
taken to remedy it. The addition of some black oxide 
oE manganese remedies this defect j hence it is used for 
that purpose by the glass- makers, and was formerly 



> NeuBUDo'* Citm. p. 55. 



SSCOI(l>AXr COMFOUKDS. 

caXitdioafi afgtais. \i too much be oscd, the glanik 
quires a purple cast ; a colour very comnion io 
window-glass made in England. In Scotland tli««ik 
dow-giass has always a considerable shade of gnen. 
As no esncc analysis has yel been tnade of itic ( 
kinds of glass, we are not acquainted with the pro| 
(ion of ill constitlienls. They no doubt vary coosii 
ably. As the fixed alkalies are volalilixed by am 
heat, it would be wortit while to examine whether, 
portion of them is not driven oft while the gltn i 
fusion, or whether the previous steps of the proccn 
vent that from happening, 
t Botth-glaJt is the coarsest and cheapest kind; Kl 
or no (ixed alkali enters into its cntnposilion. It 
sists of an alkaline earth, usually lime, combined 
alumina and silica. In this country it is composed 
sand and the refuse of the soapboiler, M-hich cont 
of the lime employed in rendering his alkali caui 
and of the earthy matters with which (hat alkali i 
contaminated. The following arc the ingredients u 
in the botde-glais manufactory of Lafond in Fraace 

Sand, from 33 to 40 

Lijclviated ashes C3 to 55 
Soda 5 to 5 



100 100 
A specimen of this glass analysed by Vaoqaeltn 




fieiridte a {iortion of pbUsh so stnall tliit if eoiild not P^ P J^^ 
be appreciated *• 

Of the different species of glassy the tnost fusible if 
flint-glass^ and tht least fusible bottlb-glass. Accord- 
ing to the experiments of Saossure^ flint-glastf melts at 
the temperature df ig^ Wedgewood, crown glass ai 
30*^, and bottle-glass at 41 ®t* The specific gravity 
bf glass differs considerably according to \\i eonstitu- 
entS4 The following are the results obtained by firis- 
won, as published in the Appendix to Lavoi^ier^s Che» 
tnisujt 

BotUe.glass . * • . .2-7325 ^^tfifm 

Green glass • • i • .2*042^ 

White glass « • , , .2*8922 

StGobintrystdK.Z 4882 < 

Leith crjstd « . .'. 3*1 8&6 

Flint-glto. . • • • • 3-329^ 

Th6 prop€frti6s that distinguish good glass are well j^ phmef : 
known* It is perfectly transparent; its hardness is ^^ 
Very considerable ; its specific gravity Varies from 2*3' 
te 4, according to the proportion of ihetallic oxide 
Ivhich it contains^ When cold it is brittle : but at a 
red heat it is one of the moSt ductile bodies known, 
tad mity be drawn out into threads to fine as to be 
scarcely visible to the naiied eye< It is almost per- 
fectly elastic, and of Course is one of the most sonorous 
of bodies* There are but few chemicid agents which 
have any action on it. tHuoric acid dissolves it with 
great rapidityi and so do the fixed alkalies when as« 



* 

* Jnr. dc Fiji. U. 4I0. 


t Ibid. tlr. t4 

Nq 



IieOVOART COMFOUfm. 

BmA n. lUted by heal. Dt Printlej bu ihoora kIm, tltu Ih 
vT' , . i' long continued sciion of hot water ■> npxble of dto^ 
poiiiiig it: A diMovcry which expUint wfidai^ 
the liliceous earth obtained b;' Boyle and Mirptf 
when they subjected w«cr lo udio«u distiUaiiaai ■ 
glass vessels. 

Mrthojot After mixing the materials of glatt together, it '» 
Jha^ usual to expose ihem for M>me time lo a moderate bat. 

This terves several purposes. It drfvci off aHcon. 
busiibte bodies which may happen to be mtstdwiA 
the sand i it produces a coaa men cement of coiibiik 
tioD which makes the glass afterwards less Ksblc ■ 
corrode the clay poll in which it ia melted; andt^ 
alkali, by this incrpi«ni combination, is not so apt tabt 
volattlixed ; which might be tbe case if the mattriib 
were c^sposed at once lo a tioIcih heftt. The tnisintt, 
after being thus heatrd, is called tlic _/W>. Through 
the domes in which the ftil is healed, it ia utiial to tct 
very thin bubbles of ghss passing ; a proof that soot 
of ihc matcnaU are volatiliacd daring this first partcf 
the proccis. 

The frit, while still hot, i> introduced intolargei 
made of a mixture of pure clay and baked clay, a 
posed to a heat snffctent to melt it completely. 
fusioo must be continued till the effervescence 
sioned by the sepiiratioQ cC the carbonic acid fnm 
soda has subsided ; and the opaque scum, knotvn by ihe 
name oi giaugali, which collects on tJie surface of the 
glass, must be removed. This scum is occasioned by 
the common salt and other foreign bodies which are il- 
ways mixed with the soda of commerce. Whea itw 



fusion has been coniinued the proper time, the fu 




kSB flowed locool s little. In that state the gUnUeX' ^ Chtp. il._ 
^VMdlngljr ductile, and readilj' a»unies any shape that 
1,'tbe Workman pleases. 

^ If the gUss vesicls, after being formed, were cooled 

npjdly, they would cotiiraci unequally, and bec<nue in 

L OBtneqtience aohritllc ns to tall to pieces whenever ibey 

1^ wtre handled. To prcveoi (his inconvenience, they arc 

tpM into ft large red hot furnace, which is allowed to 
cool very slowly to the temperature of the air. TbU 
|>rocess is called annealing. 

Gla^ is often tinged of various colours by pitxing CoI<ni»id 
ith it while in fusion some one or other of the melaJ- 
C oxides. 

Blue glass is formed by means of oxide of cobalt. 
Green, by the oxide of iron or of copper. 
Violet, by oxide of manganew. 
Red, by a mixture of the oxides of copper and iron. 
Purple, by the purple oxide of gold. 
White, by the oxide of arsenic and of zinc. 
Yellow, by the oxide of silver and by combustible 
bodies. 

Opticians, who employ glass for optical instruments, i;, jefntt 
often complain of the many defects under which it la* 
boun. The chief of these are the following : 

. Strealt. These are waved lines, often visible in 
glass, which interrupt distinct visiun. They are pro- 
bably owing sometimes to want of complete fusion, 
whirh prevents the diflcrent materials from combining 
tafiicieotly; but iu some cases aUo they may be pro- 
duced by the workmen litiing up, at two different 
tiroes, the glass which is to go to the formation of on* 
Vessel or instrument. 

Nn2 



M4 



If. 



2. Tftfrr. Theic are while 
sioocd by the Ttcrified dsjr off the 
presence of some foreign 9mIu 

3. BMIis. These are 
beeo allowed to escape. They 
plete fbsioo, either from loo licde alkah, 
cattoQ of too little heat. 

4. Cords. These are aqiesitiea on the 
glatfy iQ coosfqiience of too listlc 



rkyAi 
Vmia 
AttnE. 



rfte 



i 



CHAP. iir. 

OF S ALTS- 



word Salt was originally coWEncrf ta muriate of Dc&nitlM. 
; a substance which has been known 
Irom the remotest ages. ! t was af- 
terwards geiieraliz,edbychemivts, andenoploycdby ibeiB 
1^1 a very extensive and not very definite sense. Kvery 
body which is !>apid, easily melied, soluble in water, and 
Dot combustible, has been called a taU. 

Salts were considered by the oldei cheonists as a class 
cf bodies intermediate between earths and water. Many 
disputes arose about what bodies ought to be comprc- 
licnded under this class, and what ought to be escluded 
from it. Acids and alkalies were allowed by all lo be 
salts ; but the difficulty was to deteroiine concerning 
earths and metals ; for several of the earths possess all 
the properties which have been ascribed to salts, and 
the metals are capable of entering into combinations 
which possess saline properties. 

In process of time, however, the term talt was re- 
stricted to three classes of bodies; namely, acids, alka- 
iiet, and the compoundt which acids form with alkalies, 
earths, and metallic oxides. The first two of these 
classes were called limple salts ; i he salts belonging to 
the lAird class were called compound or neutral. This 



9«S 



BZOOXDART COMrOBITDt. 



— y^' K. tulai>peIl>tioti originated from an o|Knionloog« 
<■ I ^1 ■■ uined bj chemiiii, that acids »id alkaliei, o( w)ui| | 
thcj are coDapotrd, were of a contrary nsiur?, at ifai ' 
they counteracied one amnber ^ to that ibeiewliiiu 
compoundi posM&sed neither (be properties of addiu 
of alkalies, bot properties in termed iate between tbc 
two. 

Ciiemittt have Utely restrietcd the leTto mi aQ 
more, by lacii))' excluding acid* and alkaliet fron ^ 
cbii of lalis altogether. At present, then, ti daiom 
only the compoundi formed bjr (he combioitioo t| 
acids with alkalies, earths, and tnrtaMic oxides*. 

No part of chemistry has been cultivated with mote 
zeal than the salts, ctpecially for these last 40 mn. 
JJuring ihat time the number of saline bodlct has bew 
enormously incrensed, and the properties of a s 
gnM number ha-ve been determined with predil 
Still, however, this wide and importanr regioti JtH 
from being complexly explored. 
f Chemists have agreed to denominate (he salts t 
the acids which they contain : The earth, alkali, i 
metallie oxide, combined with thsu acid, ii cillc^||| 
iatf uf the salt. Thutcommon salt being a compc 
of muriatic acid and soda, is called a muriate, and *o£ ' 
is called the base ofcommon salt. Now since there tn 
34 acids and 05 bflses, it would appear, at Gnt ugfit, 
(hat there are 2210 salts; hot of the 53 metallic oi. 
ides at present known there ire a considerable namber 
which cannot combine with all the acids. This it 



ij'l itid Hrxfri/ itll irc often tonfoiisdtd. la thli ■ 
i/ it cunfincd to sjIm hatiox no oicca of acid ar l» 




bubis. 



sen 



0W case nlso with silica, snd perhaps with some of the _^*P - 'H. 
otber earths. We must therefore subtract all these 
deficiencies from (he lull number 2210. However, to 
eompciiSAie this, at least in pan, cheie are several ncida 
capable of comhiiiing with two bases at once. Thus 
the tartaric acid combiner at once with potiisb and soda. 
Such combinations are called trifiU salts, and ihey in- Triplenlu. 
create the number of salts considerably. There are 
SDme sails, too, which are capable of combining with 
■n addltioaal dose of their acid, and others which com- 
biae with an additional doseof their base. The French 
chemists denote the tirst of these combinations by add- 
ing to the usual uame of the salt the phrase wub ^xcest 
nf acid, or by prefixing to it the word acidulous : Tiiey 
deootc the second by subjoining the phrase with «xrfjj 
nf bait. This oaeihod has the mertt of being precise ; 
bur it is awkward and tedious. The ingenious mode of 
OMning these combinations proposed by Dr Pearson 
ought certainly to be preferred. Jl is equally precise, 
if not more so, and far more convenient in every respect. 
It consists in prefixing to the usual name of the tall the ^"P"^* 
preposition .Ttt^^, to denote an excess of acid, and the uhi, 
preposition luh, to denoie an excess of base*. Thus 
stilphati af potash denotes the salt in its slate of perfect 
neutral I zai ton, without any excess either of the sulphu- 
ric acid or of the potash ; luptrmifi/ale i^ potash is the 
same salt with an excess of acid; snhsvlpbatt of pota^ 
is the same salt wilh excess of base. These three di/. 
fereni Linds of salts must increase the number of saline 
compounds very considerably ; but the precise number 



* Tcttsoa't TniiMt* 'fttt Clmicat Ktwm.-htt^-.-.jh sf' 



I 



t marethui lonUtn-l 



of salts is not known, b« man^ of Ihcm rcmstn itrH n. I 
examined by chemists. Propabl r there ate mi niA 
fewer than aooo. Some idea may be {ArmtdnfAi 
projrre&s which this branch of cbemistvy hai mtdr, iy J 
recollrctmi; that 40 ycnrs aga n 
all were known. 

Of these 3000, however, a considerable number mfU 
be considered at still unknown, aa they have been n 
ly formrd without being ej»mined. Oflboie a 
are known, lite greater number have not been ap^k)' I 
(o any use, and ihcrelore do not deserve » rerjr f 
lar description. 

As the difK^rcnt genera of salts are denominaied fras 
tbeir acids, it is evident that iherc must be ti miaf 
genera ax there are acids. The termiftstions of 4% 
names of these genera difficr according to tha natiirt 
the acid Vfhich constiiuiei ihem. When thai actdtc 
tains a maximum of oxygen, the termination of tbe ^ 
nut is alt ; when it does not contain a maximum of o^ 
gen, the termination of the gamis t» »Ve. Thui dtt- 
salts which contain sulphuric acid are called n^»^«^ 
those which contain sulphurous acid arc called nt^MMJl 
This distinction is of some consequence, because ll 
sails differ very much, according as the acid ti saiund 
ted with oyygen or not. The itet are seldom perms-^ 
nent; when exposed to the air, they usually aiiractf 
pzygcn, and arc converted into afet. 

Kvery particular species of salt is distinguished b 
subjoining to the generic term the name of its bamf 
Thus the salt composed of sulphuric acid and soda i| 
flailed sulphate af soda. Triple sahs are distinguished 
by subjoining the names of both the bases connected by. 
hyphens. Thus the compound of tartaric acid, potuji^ 




■ filTS. SflJf 

k 

ttttA so6a, is tilled tartrate of potatl>-a)id-joda. An- Chip. IIL 
ttber mode of naming these triple salts is sometimes -^ 

^'bllowed. One of the names of the bases is prefixed to * j 

^Ihe generic name so as to act the part of an adjective. ■* 

^For example, soda-tnurtatc of rhodium, means the triple 
B^BsIl composed of muriatic acid, soda, and oxide of rho- 
>^dium. Sometimes the name of the base prefixed ,is sl- 
, . tered a liiile, as amtntmio-siilphate of magnesia {sulphate 
of magneiia-Wtd-ammonia) ; ferruginout sulphate of %inc 

h(tutphalt of juinc-and-iron). This is a less unwieldy 
mode of naming the triple salts, but it is not always 
■ possible to employ it in our language. 

Before the correction of the chemical nomenclature Arrange- 

P by Morveau in 1781, chemists usually referred the ge- 

, nera of salts to the bases, and distinguished the species 

by the acids. That celebrated philosopher entirely re- 

j versed the method by introducing ihe new generic 

^ terms formed from the acids ; and his ingenious na-> 



li 



in«nclaiure having been sanctioned and improved in 
1*787 by Lavoisier, Berthollei, and Fourcroy, whojoin- 
cd with him in forming a new chemical nomenclature, 
has now become universally prevalent. As far as re- 
lates to the salts which have alkaline and earthy bases, 
this method introduced by Morveau is certainly pro- 
per; for in them the acids in a great measure stamp the 
character of the salt, and therefore ought to constitute 
the generic distinction. But it docs not apply equally 
well to the salts whose bases are metallic oxides ; for 
in them it is not the acid but the base which stamps 
the character. In them, therefore, the genera ought to 
be reversed; they ought to be derived not from the 
fcids but from the bases, or rather iiora the metaU 
frboM oxides coustitute the base. 



. The ulu, then, natorally divide ih«in 
I gnntt cla«»c» i the ftru ofwbich cotnprrhi 
'I line and carthjr ullt, which derive theii mott 
chuaclers from tlieir acids ; the secoDd en 
ihe mctailtnc salti, whose baacst on tbc coQir 
their DoU impottaiitpiopertict. I shall dM 
vide thii Chapter into two Sections: in- I 
which I »haJl deicribe the alkaline aod Ofdj 
the Mcosd, tha oMialline* fl 

SECT. I. '4 

or ALKilXIHE AHD EARTHY SJi^R 



A» the lahi belonging to this Sectiaa maj b 
will) great propriety according lo their i 
Buurally divide tliemselves ixto 34 g«tMr«» 
ticuUr acid cooMituiiiig a genus. But ft tta 
Mico nusi be omitted altogether ; becaoM 
iriiicfa belong to them have not been examiaa 
gcont will comprehend under it u niuijr •peei 
■re biaea » bcaidea the tripU ulta and liw tm 

A> these genera are verjr numerooSf H i 
tended with considerable advantage to the 1h 
Mibd<v<<l* them into sets according to I 
Yliitit fttttrnptcd in the folivwing TabU 



SAXrXS. SftI 



Table of the Alkaiim anJLEarAf ScMs. Citoy.HL 

IncombttstiUe Salts. T«bk«f'tlie 

a. Not altered when heated with combustibles. 

1. Muriates. 

2. Fluates. 

3. Borates. 

4. Phosphates *• 

i. Decomposed without combusSioa when heated 
with combustibles. 

1. Sulphates. 

2. Carbonates. 

c. Set fire to combustibles, or jield cOcygen gas 
hj heat. 

1. Nitrates. 

2. Nitritest 

3. Hjperoxjmurtate^t^ 
4* Arseniates. 

5* MolyhdaUs* 

6. Tungstates. 

7. Cbrcmates» 

8. ColumbaUsX* \ 

L CSombustible Salts. 

a. Acids partially dissipated, Icaying salts in tf/^« 

1. Sulphites. 

2. Phosphites. 

^. Acids totally dbsipated, lcavin|; the base and 
charcoal. 



II II I , wn ' I 'l l! i i:^ 



* Ffiosphate of ammonia is dttompoted hj heat and tumAmMa, 
\ The nitrate and hyperoiymnriate of ammonia are comb m t i hic aiooa. 
bey disappear completely when heated. 
I The genera io italics arc plaacdfrora anabgf co^ 




^ . siconMUiT eoMMovm* 

1 1 ' Arl li | i^ |w h rtj r iBiMinwwl nMtewi* B is 

9* SocdntieSto ■ in 

9. Morozylmtef. ■ c 

4. Benxo«tes» ■ j 

4-+Aoidt wholly deoompotcd^ 
& Onbte* ' 

7. Mellaiet. 

8. Tartntrs. 

9. Citntet. 

11. Saccobitet. 

12. Untes« 
IS. Sebates. • 

14. Malate^. 

15. Formiates. 
10* Sobcratai. 

11. Grallates. 
18. Prasiiatea. 

Let Qfl take*a view of all theae genera, fellowing die 
order of the Table. 

As the salts coostitote a class of bodioa of great ioi- 
portance to the practical chemist^ bot so numeroos that 
It IS di£Bcult to remember the properties of each, it isof 
abme importaoce to facilitate the meana of compariog 
them together as much as possible. It will contribnte 
considerablj^to.tbis if the salts belonging to each geiras 
be described ezactlj in the same order. This shaU be 
attended to as much as possible in the f<dlowing accoont 
of the salts. 

The importimce of the salts as chemical instromeats 



t4LT9« 



fii 



as very much^'connccted with their solubility In water. ^^Np^m*^ 
Some are insoluble in that liquid, others dissolve in it 
with more or less facility. I shall laj hold of this cir- 
cumstance to subdivide each genus into two parts : the 
first shall contain the salts which dissolve in water ; the 
second those which are insoluble. Many of the salts 
have not yet been applied to any useful purpose, while 
others are of importance either to the chemist or for the 
purposes of civilized society. After having described 
the properties of the salts belonging to each genus, I 
shall add a third part, in which some of the most im- 
portant uses of the salts shall be mentioned. It will 
hot be expected that I shall indulge in minute details^ 
or attempt to exhaust so fertile a subject. Eachgenns^ 
tben^ as far as possible, will be divided into three parts } 
namely, 1. Soluble salts; 2. Insoluble salts; 3. Uses 
of the salts of the genus described. 



• * 



ORDER r, 

INCOMBUSTIBLE S.4LTS. 

CfNUS I. MUUATES. 

Xhc mariales ve the salu which have been Ic 
known, and from vrbich indEcd the whole of 
have borrowed their name ; for to Ihcn beloogt com. 
tnon salt, the molt JmportBiit and the most Indiipcnubl; 
necessary of all the sslts. Tliejr ma/ be dUunjuubed 
hy the following properltei: 

1. When heated, tliey melt, and are volotiliKd, ■ 
Icui in pan, without undergoing decompoaitiuQ. "ttt 
first portions which &y offconiain an excess of add. 

2. Not in the least altered by combasublei, n 
when assisted bj heat. 

3. Soluble in water. For the most part iticj n 
the boiling point of water. 

4. ElTvrvesce with sulphuric acid, and white ac 
fumes of muriatic acid are disengaged. 

5- When mixed with nitric acid, ihe^ exhale the p 
dour of ox^muriatic acid. 

The alkaline and earthy muriates at present kst 
amount to twelve. 



Sp. 1. Muriate of Potash. 



This salt was formerly called fehrifugt or d^titni 
salt of Siivwt^aad rtgtneratid ita tall. 



515 ' 



It may be prepared by dissolving potash in murinilc 
Bid, and evaporating the solution till the sail crystal- 
Kesi but it is commonly obtuned during olber chcml- 

. processes. 

It) crystals are cubes, but often rather irregular. 

It has a disagreeable bitter taste. Its specific gravity 

1-836 •. 

When boiled in water, it dissolves in 1-7 times its 
rcighl of that liquid +. Ii requires three parts of cold 

■rcr J ; but this difference is not sufficient to enable us 

obtain regular crystals by allowing a saturated boil- 

g solution of this salt to cool. Regular crystals can 

ily be obtained by abandoning the solution to spoa- 
■ncous evaporation. 

It suffers little alteration from exposure to tbe air. 

Wheti exposed la heat, it decrepitates, melts when 
icated to redness, and at last is volatilized in a white 
anoke, but without decomposition. In a red heat it 
loses 2-86 per Cftit. of its weight ]|. 

It is not sensibly soluble in pure alcohol. 

Many different analyses of this salt have been pub- 
Sshed, but they by no means agree with one another, 
fbe following Table exhibits the constituents according 

tbe respective znalists. 



n Wenzcl, Ibid. p. ]ia. 



DiriHoalll. 

Coniptsi. 







t 


t 


J 


II 


"X 


Add. 


21 


" 


31 


34 


35 


36 


Base. 


1 + 


»3 


01 


dO 


05 


6* 


Water. 


5 


' 


8 








Toiai. 


100 


lOOl 


lOO 


too ino 


mo 



TliCK results appear altogether irrecoDCileablt 
cacli other; but ihc i]iir:rences arc rather appuou 
real. The quantity of muriatic scid w»s estimi 
precipitating it by means of nitrate of silvert icd 
ing the muriate of silver obtained. Now Bi 
formed hii esiimaie by luppoatng that lOuparlt 
ate of silver coniain only ir5 muriatic aciJ, 
ihey seem in reality to cgiiiaia IS. Ha^I be lucd 
true proportion, the quantity of acid instead of 21 vgtU 
have been 33. The water was estimated by czpoW 
the sill to a red heat ) now io this tctuperaturc, loocil 
the acid probably escapes as well as the water, C(m 
the whole, the estimate of Wenzcl appears to mc to k 
the nearest to accuracy. 

5^. 8. Muriate of Soda. 

This salt has been known and in comoica use n i 
acasoDer of food fram the earliest ages. Ii ia knomlrr 




ii. i wkgkb, an. 

fBttgmin, Ofi.u. ,. tj4. ) Rok, Gdilcn*) /ht. *i.]i. 

H Woitcl, ''iruia'Jiiiia/i, p. loo. The water ■■ n 
1 KitwtB, Nicheboti's ^*r;* /or. iii, »ij. 




MOMATES. 



377 



of common or tea tall i someiimes it is called Chap. tH-^ 
gtm. In this coumry the term salt is usually ap- 
ed toil withoui sny addition. The nature of its acid 
IS discovered bj Glauber, if it was not known earlier. 
kbl afBrms in his Speemtn Beccberianurn, thai its base 
an tlkah j but Duhamel was the first who show- 
. bow to obtain that buse in a separate state, and who ' 

ntonsiraied the difference between it and poiash. 
This salt exists in great abundance native, and there- 
re is ticvcr formed artificially' by cbcmisls. Immense 
MKS of it arc found in different countries, which re- 
dre only to be dug out and reduced lo powder. In 
tU state it is called rod lall. The water of the ocean 
40 contains a great proportion of ihis salt, lo which 
taste, and the power which it pos- 
Essei of resisting freezing till cooled down Co SS'S". 
(Then ihis water is evaporated sufficiently, the salt pre- 
pitales in crystals. It is by this process that it is ob- 
liiwd in this country. But the salt of commerce is not 
ifficienily pure for the purposes of chemistry, as it con- 
itns usually muriate of magnesia, &c. ; but it may be 
Ibtained pure either by repeated crystallizations, or by 
he following process: Dissolve it in four limes its 
ireight of pure water, and filter the solution. Drop in- 
solulion, first of miLri»re of barytes, then of car- 
lonale of soda, a» long as any |r ci|]iiale coiiliiiues to 
ill. Separate the precipraii-s bj filiation, and cvapo. 
me slowly til! ll'c 'alt crysi-.l ^c^. 

Muriate of soda usually cry!itai<<zet in cubira, whtc^, T^ropcrtiei. 



iccoiding to Hauy *> 



itht 



pnmitive form of iis crys- 



SALTI. 

taU vii of it« mtevrant [nrticlei. Sonethool 
I of ihc cubes «ie truncated ; and 'n urine thei 
common *ali, a* Koarcroy and Vtuquelbi kl 
tuned, aisumc the form nf octahedron!. 

Ill tanre it univrrully knnwn, and \% adii 
ly ipcak.ii))[ dc no initiated imh. It> specific 
3-135*. AcrordinK to Bcrgmiin, it is uIbI 
liiDei its neiKht of cold water, and in fK 
weight of boilinji; water f. MThen it iabeile 
lime in water, it diswlves in K'50 times iu 
thai liqnrii X- The specific gravity of 
lutioH ii I-IPB, trmpmture ■♦s^J. Pure al 
not diiwlve tbii suit, but it is somewhat so] 
ctthol of *S30. 

It in not ■S'rcted by eipotnre to dry air. T 
of (oda of comiicrcc. indred, contains a quaai 
riiie of ma^netia, which renders it deliqa 
coniiini alto Hulphaie of mif;neua and fulphi 

When heated, it decrepitates. In a r«d bl 
and evapnraKS in a white smoke withoat 1 
decompatrtion. In a rvd heat it losea abattt i 
of iti weight II . Part of this loaa t* to be ■ 
the mBrlalic acid ^. 

The follotrinji Tablv exhibits the result of 
ou* analytn that ha\-e been made to asocnaa 
portion of the coasiitBtnis of this salu 






■ 


+ 1' 


4 


11 


IT 




Acid 


23 


38'98 


40 


43-20 


40 


52 


44 


Base 


00 


53-00 


53 


56-80 


54 


43 


50 


'Water 


e 


8-12 


2 






6 


6 


St.,:^ 


too 


100 


100 


100 llDO 


100 


100 



Chip, m. 

Compotl- 



[ha imall proportion of acid obtained by Bucholz is 
ribed to his mode of cstimaling the constitu- 
S of muriate of silver. When corrected it would be- 
ne 44'3f which approaches the result obtained hy 
Mid ai it is nearly a mean of the analyses of 
pirwan and Bergman, is probably very near the truth. 
"he last column, then, founded on this result, is an ap- 
nxiroation to the constituenis of muriaie of soda. 

Sp, 3. Muriate of Ammonia. 

This salt was known to the ancienis, and was called , 
T them sal ammoniac, because it was found in great 
|ii«Bt!ties near the temple of Jupiter Ammon in Afri- 
composition was first pointed out by Geof- 
toy junior in niS and 17Z3t+, and afterwards more 
kIj by Duhamel in l~35tt- for many years 
e whole of the sal ammoniac used in Europe was im- 



t Kjrwio, NKholunV ^tit 

I Wicglcb, Buihalx, Ibid. 

k 1 Wenicl, FrrainJiiitiafl, p. 



$ ROK. Gehkn'i /wr. <n. 31. 







'X 



MURIATES. 



591 



this salt is sublimed with gold leaf, there is ^^"P- '^ 

;fae neck of the retort an ametlijst-coiouted 

ordering on purple, soluble in water, and iorm- 

pie solution. When filtered, there remains 

purple powder. This salt seems Irom this to 

le of oxidizing gold *• 

mstituents of this salt seem first to have been 

d by Tourneiort in 1700 ; but he did not suc- 

Acertaining their proportion. The result of 

ent experiments made for this last purpose is 

i: 





t 


X 

40 


J 


II 


IT 




1 


31 


42-73 
2500 


49 


7(5-3 


48- 




69 


60 


51 


23-7 


14-9 


tcr 


32-25 




37-1 


>1 


100 


100 100 


100 


100 


100 



Compoti* 

■tion. 



»w estimate of acid in the analysis of Bucholz 
as has been already observed, lipon h state- 
the proportion of acid in muriate of silver. 
•rrected, the true number turns out 48 Which 



r.C^eli't Krw Dui9veri»4^ &C Part u. p. 41. 

f#, iii. 146. I Wiegleb, Ibid. 

UcB0jt^ p. 102. 
tbc ffCMik of ao aaaljn, but of a cakvbtion fonodeA 
, that cqaal bolkaol animohia<«l and muriatic acid gas 
1^1 which iajiot ^ from tbetmtb. Id the fint aa4 
ii iacladcd in the proportion of bate auted. 



lomea verj aear the evtitnate of Wcnrel. Utbeoi. I 
< mate staieil in the >ixih coluinD of the praecdin); TiUt I 
be nesrlj correct, t,% is to be presumnS, ihcn tbt nwa I 
in 100 parti of sal Mtnmoniac muM antotmi (o }rL I 
From these data, the numbcira iu the last colimn ifib 1 
Tabic were obtsincd, which exhibit an approxnutia I 
to the true pioportions of the constitocnis of this tk. 1 
Variations iu ibc propnTlion of the water, which ^ I 
be expected in diffirrent tamplei, will acctnuit for Ai j 
discmdaoce in the different aijalyKa exhibited abort. 

5/. 4. Mitriate of Magtutia. 

This salt exists in sea-water, and in s«verat niixiil 
springs, particularly that at Ljrmington in HampiliiK. 1 
It was fitsi described bj- Mr Brown in the Philowphiol J 
Traniaciions for 1123 *; but iu composition was B4 I 
uiicferstood till long nflcr, when the experiinenti <{ J 
Black and Margraf had established the pecaKar natare T 
of iiii base. Bergman aficrwafd* published a detcn^ j 
lion of it t- 

As it i> found native in abuadance, it is leldna I 
formed ir iliciaJIjr j but it may be prepared byditaolring 1 
CJitbouate of Oiijaeiia it) muriatic acid, mnd evapontinc j 
th^ solution to » propCJ- coniiiicncy. 

It is not easily crystallized. Bergman's inctbodiru 
to evaporate it by a conatdcrablc faeatto the propcrde- 
gicc of coiiccniraltun, and llien to expose it to a si 
cold. By this method he obtained it tn stDall an£ 
Its specific gravity is l-fiOl }. 



, • na. IViBM. tixll 34S. \ (>«i. i. j8i. 



MUXtATBS. 389 

I taste is extremelj biiier, hot and bi'^Df;. It re- ^'P 'P-_ 
m raiher more than half its weight of water to dia- 
I It { for when exposed to the air it runs into a !■• 
I and attracts ^^ parts of its weight of water ". 
tolubility in alcohol increases wirh the sirenglh of 
liquid. Alcohol of 817 dissolves half its weight 

but alcohol of -900 onlj |rh of its weight t. 

sataraCed solution of it quick]; forms a jelly ; oa 
b, if hot water be poured, spongj masses are form- 
Dt even soluble in muriatic add %, 

deliquesces very ipeedil; when exposed to the 



strong heat decomposes it completely, according 
turcroy. When dried in a high Icmperaturc, it is 

le followiog Table exhibits the proportions of its 
iiueuts, according to the experiments of difierent 
ists: 





II 


ir 


• • 


Acid 


34 


34-5g 


57 


Base 


41 


3101 


43 


Water 


25 


34-34 




Toul 


100 


J 00 


100 



Ettcmaii. Ofiur. i, 13a. t Kiiwsn »■ Mimtnl WMtTi, p, ST«- 

irpiun. i. '^t. f Wntniml), Ami- Ji Ctrm. n. 13;. 

rgquu, O^wi 1. ij6. 1 Kuwan, NioJk ^M<t/)k>'. tikSij. 

IVtnicI, Vimam^utafl.f. lOj.. 



■-<1l 



lime 





bv 

# 

del 
Ct 



l< 




Uf^ 



7 tilX ui* ia* btjes 




lf*t*ttc90f^Ui. J 7*. 



f ^<iw. * Cus. jr. sxi 



isually prepared from the residue of ihat pro- Chap, nr. 
I it may be oblained b/ dissolving carbon^El: of 



-ysinU are «ix-sided slria'ed prisms, terrainati-d pc«perckB.a 

' sharp pyramids. It is not cnsy lo procure it 

:als, in ccin»ec)tieiicc of iis cxlreme lendency :o 

ict. Indeed, In summer, it is nexl to itnjjo.sJ' 

procure good ci ysials ; bal in winter they toita 

eouily, if we dis&oUe four pans of the salt in 

wsler, of llie temper^iture of "O", and expose the 

I in an &iinosphere of 33°. 

taste of this salt is very bitter and pungeat. lit 

graviiy is 1*t6 ". 

extremely soluble In water; water at fiO" di^ 

very nearly four times its weinht of it. The 
iiv diminishes very rapidly wr.h the tempera- 
U^nce water at 30* ilae* not dissolve above half 
arttity, while at lOO" it dissolves any quantity 
liatever. In hot wenihcr, there. ore. it cnnnot be 
din crystals, but only IT a hard, white, solid mass. 
Walker has ascertained, that when the evapora- 
the so'ittion is carried on till its specific gravity 
SO at the temperature of SO", it crystallizes 
EXfoscd to an atmosphere whose temperature 
. When its specific gravity at 80* Js 1-4S0, 
noes on cooling [he form of a hard pearl- coloured 



)hoI dissolves this sa!t so copiously when con- 
ed, that I presume itis capable of taking up con- 
»Iy more than its own weight of Ibe salt, evea 



f N'ictiulran'4 Jo- rnJ. T. Sl6. 



thnneh previonsljr expoied t< 

,' thr moisture. So much beat 

luiioQ as to causF the alcohol 

Wheo this silt is «zpe>ed i 
turr very speedilj, uid dcliqu 

When expoied to the aetic 
nclrs, and then loses its watt 
violent heat separates a small ] 
thus rcdaced to a lubmuriale, 
ning in the dark, as Hontberg 
has been called the phatfhorms 

The following Table ezhibi 
ent experiments made to asce 
this salt, not in the stale of crj 
to a dry mau. 



Acid 


31 


- 


Base 


44 




Water 
Total 


25 
100 


1 



These analyses diScr very mm 
of Itirwan is nearest the mean, 
correct. 



•Bergnv,!. 136. Thri.lin 

t Kir«.n, NIdiul*.!.'. ^ i. 

ycncA in a red hcai before mm vt >. 

(WcMfl,/'.ftM«/,.i»/(,p,l 



jflltl 



Sp. 7. Muriate ofBaryUi. 

The properties of this salt were first investigated by 
feheele*. Dr Crawford wrote a tr«ameon it in noo. 
Knee that period many procestea have been published 
preparing \k\. To Kirwan, Hauy, Bucholz, and 
Bouillon La Grange, we are indebted for most of the ad- 
jditions made to the description of thia salt by Scheek^ 

The easiest method of preparing it would be to dis- Pnptrj- 
bolve carbonate of barytes in water and crystallize the 
volution ; but as the carbonate of this earth is rare, the 
[Ult is usually formed by calcining in a crucible a mix- 
'tnre of sulphate of barytes and charcoal, decomposing 
■'by means of muriatic acid the sulphurel formed, filcrz. 
[ting the solution, evaporating it till a pellicle begins to 
•form on its surface, then allowing it to cool slowly. The 
.crystals of muriate of barytes gradually deposite. If the 
'^alt happens to be coniaminaied with iron, which is 
'often ttie case, the crystals are to be calcined, dissolved 
.in water, the solution filtered and crystallized again. 
By this process the oxide of iron is separated. The 
improvements proposed lately consist in promoting the 
fusion and decomposition of the sulphate of barytes, by 
adding to the mixture sulphur, muriate of lime, or com- 
inon salt. 

The primitive form of muriate of barytes is, accord- piopenie 
' ing to Hauy, a four-sided prism, whose bases are 
squares. Its integrant particles have the same figure X. 



■CKir(..lnu;i,iu.6. EDgiish Truilitioo. 

+ Se»V»DMoiu, ywr.A /'iji. il», 197. Gotu^iv^, Pbd. Mai.txa. 
4l)8. Bouiltou Ij Orange, .4».^cC&n>.iWii. IJ9. Re-it, Ibid. It.JI. 
) Fwrcro;, iii. a|i. Englith 'Xna% 



It cr^'ttaltJEn tgost efratmonly in Ubics. ScnciiiRn 
mttiDC^ the form of two «ighl'S>dcil pjimjiids sp}a44 
bair le buv *. 

It hu a pungcnl aiKl very disagreeable tMt , mi, 
like all the oilier prepaiatiMii oS bar/tcs, >i pasoMu. 
It« tpcciiic grtvii^ is 2'Sa5'I K 

ll requires i"i» pacu of water* af the tenptntKc 

IQO^, to dtstoWc one of this salt. It is ■caTcelj' Icnn- 

hiubic in cold Kitcr. Hence it cannot be prooirad n 

F eryiiils hy cocking a satuiaud soiutioti of it in bat «*. 

t«rl. 

Froia the expcrLtncDli of Bucbolz wre learn, ihupon 
alcohol white cold diswlvei no sensible portion ef iii 
but at a boilinf; heat it is soluble in 400 parts of tbtd ii. 
quid f. Weak alcohol dissolves a little of it, and tW 
solubility increase* with the dilution. Alcohol of "OOO, 
Jpr intiaoce, dissolves T-rn of its neighl of (his uli ||. 

It is oot altered by cxposnic to tbc opcD air. Wba 
heated, it decrepitates and dries, and when tbctciopcn- 
' ture is very high it mdis ; but do heat which we an 
apply is capable of decomposing it. 

The following Tabic exhibits tlic experiroenii aiidt 
by cUcmtsts to ascetiain the proponion of its cnutiru- 
cnts. 



1 



• Cnwianj. 

t HdMRfnti, Jin*. JtCiim. iivin. i^ 

t Cr.«fr.r.l. f Btftr^, B. U 

t Kii«*». ill MimtTjI H'sUn, p. ST4. 



MURIATES. 



5S9 



i 


* 

20 


^ 


* 


t 


Acid 


22*93 


23*8 


24 


Base 


64 
16 

100 


62-47 


•;6'2 


00 

16 

100 


Water 


14"o0 


. ■ '■ 


Total 


100-00 


• ■ * i 

'100 ' 




These analyses a^Yee nearly witheadi other. Mr Kir- 
^van'Sy from the great care with which it was made, 
seems entitled to the most confidence. 

^» $• Muriate of Stroatiam, 

This salt was first described by Dr Crawford in 17P0« 
It was afterwards examined by Dr Hope, by Klaproth, 
Pelletiery Fourcroy, and Vaaquclin. 

It may be prepared by dis^lving carbonate of stron. 
tian in muriatic acid, or by decomposing suiphuret of 
strootian by means of that acid. The solution is then 
to be evaporated to a proper consistence, in order to ob- 
tain the muriate in crystals. 

Its crystals, according to Hauy, are very long, slen- Propenan. 
der, hexagonal prisms \. It has a peculiar sharp, pene- 
trating taste. Its specific gravity is 1*4402 ]|. 

Three parts of these crystals are soluble in two p^rts 
of water at the lempereture of eo^. Boiling water dis- 
solves any quantity of them whatever ^. From the ex- 



sz 



* Kirwao, Kidiolion*! i^«rf« /mtm/, iii 25: Tlie sak ia the tecood 
ccdoom was in cry^aU, in the fourth dried 
f Aflcen, NicholioD*t /Mr. zxii joi. 
% Fdurcroy, itl 236. EngL TrasA. { lb. 062. 

1 Matsenfracs, Amm, de Ctim, xxYiii. 12. 
i ikf coidiog to Crawford, they dinoli e In 0*825 ^ water of the tern* 



penmentsi 
alcohol, at 



f Bucbol; 
he ictnpcrtii 



: learn thM S4 putt tf |» I 



inreofeo*, Staohmmt 



P«>< 



this ult land tbat it ii Mtlable in 10 paru of part W. 
ing alcohol *. The alcohol Kiluiioo burai wiiii « ^ 
purple colour. 

The cryatil suffers no change when cspotedteAt 
Btr, except i[ be very moUt jin which case tbey dtfr 

When heated, the; lirn undergo the vtmutj bmm, 
and arc ihcn reduced lo a white potrda, A vaj vittai 
beat it said to decompose this sail. 

^lurialic acid,prccipi(atea this salt fraa its soloba 
in water f. Hence it crystallizes most readil/ vba 
there is an excess of acid in the solution. 

The constituents of this salt, according to the ihIt- 
tes hitherto given, are as follows : 





t 


i 


t 


M 




Acid 


" 


23-6 


31 


38*33 




Bmic 


4D 


36-4 


69 


61-07 




Waler 


42 


40 








Total 


]00 


100 


100 


lOO'OO 





Sp. 0. Muriatt oj' jllumma. 

This salt was first described hy Margrof ia his di»- 

senatioa on the Earth a/ Alum, published in the Beilio 



pennrc 190°; but thtj are mndi lea toluble In cold water. Hon 
ibej' cr)Milliic in couling. 

• Bucholi' Ritr^r, iii. 19. f Ki^. 

I lUrwui. NichoUno'i ^ rf Jtwr. iii. 115, 

} Viuqarlm, V.mnrtj. ui. S«J. Eogl.Tnsi. 

I ReM.Ochlcn-« J.^. iri. jj- 





591 



lion has been CTn| >. HI. 
\d, except by Bu- 



rialicacid: 



the form of cry. Propert««. 
or in the slate of 



'ecnoirs for 1 154 ". Scarce! 
lade 10 ihc facrs which he 
holi: + and Wenze! %. 
It is prppared by dissolving alu 
is always in the state of a supei 
It is scarcely possible to obtain 
,U: it is nsually either gelatin 
bite powder. 

It is extremely soluble in water, one part of that lU 
id being sufficient to reduce four parts of the dry salt 
the consistence of a syrup J. When exposed to the 
ir, it speedily deliquesces into a liquor of a glutinous 
insistence. 

Pure alcohol, in the mean temperature of the atmo- 
iherc, dissolves half its weight of this salt ; and when 
itling, it takes up at least iwo-thtrds of its weight, 
ml deposits again a part as the solution cools ^. 

When heated, it melts and loses its actd, while the 
llumina rcmains.behind in a state of purity |] . 

Its constituents, according to the analyses hitherto Compon- 
lade, are as follows : 





** 


*k 


H 


Acid 


19 
30 
51 


2g-8 


27 1 
72*3 


B»e 


30-0 


Water 


40-2 




Total 


100 


100 


100 



■ Mirgnri O/ui.'.ii. Ii8. t Bn'raf*,iii. tog. 

t y,rt<ia/iitiuti/i,p- 1 IT. f Buchala, Ibid. p. II5> 

1 MtrgtaT.md. Ib'Jptll- 

• • Burhpli, Ibid. The leeonil calumfi conwUn hit idiIthi u he 




The« atiilrw^ >rp aIto([«her 
suppose that Wenxcl'> earth 
Wju not dt'ud sudicienllj. 

Sp. :o. Maria 
This salt has been examin 
quelin f, snti KUprolh %• It 
to the nitrate of ytiria. Like 
ficnlty, melts in « gentle heat, 
Tf rapidl^r from the atmofph< 
lixe, but mni into a jell/. 

Sp. 11. Murial 
Tbis salt bu onljr been exa 
little more knowa at ptcs< 
ties than that it rctembletnitr 
osil; crTstallized. Whea c 
it forms an agreeable sweet lii 

Sp. 12. Muriat. 

This salt was first examii 
aftrrwards described more pai 

It is easily fbrmed by pour 
]y precipitated zirconia. It 
very astriiigeni j by evaparati 
p:tr«Dt crystals in needles, whi 
iu the air. Muriate of lircoi 



r:lr* ',• ; th' ihiH t'\i t^EK laaljkt, 
ii •'('■ •-r.rtf clujd. , 



MUXIATtS. 609 

-p„ „ in alcohol ; to the flame of which it does not ,t^»P- ^\ 

fmnmiinicate any particular colour. Heat decomposes 
4ti and it is decomposed likewise hy the laliv^i when 
ihe mouth. 
When muriate of zirconia contains a little silica, it 
.bic crystals without consistence, and resem- 
liog a jelly. These cryaials, when exposed to the air, 
adualij lose their transparency, and diminish in vo- 
; and there are formed in the middle of the salt 
•rhite silky needle-shaped crystals. 

Muriate of iirconia is decomposed by sulphuric acid ; 
part of the sulphate precipitates, and part remains dit- 
lolved in the muriatic acid. When this acid is driven 
iff by heal, the remainder of the sulphate is gradually 
kpo&iied : if the evaporation be stopped before the 
BSM be reduced to dryness, it forms a kind of jelly 
vhcii cold. It is alio decomposed by the phosphoric, 
citric, tartaric, oxalic, and saclactic «cids, which form 
llh zirconia insoluble compounds that precipitate in 
hite flakes. 

The pallic acid poured into muriate of zirconia pro- AttionoT 
* ,_. . . . ,. :, ■ galUcaeii 

duces a white precipilaie ; but a greco, bordering on 

grey, if the zirconia conlai ts iron ; and this last preci- 
pitate becomes, when dry, of a bright black colotir, and 
resembles China ink. Tie liqud preserves a greenish 
colour : new portions of gallic acid produce no farther 
precipitation ; but carbonate of ammmiB separates ia 
great abundance a flaky matter of a purplish colour, 
not unlike that of the leys of wine. From these ex- 
periments it follows, that gallic acid ha» a greater af- 
fifiitjr for zirconia than muriatic acid has ; and that the 
lea of zirconia and Iron are soluble ia muriatic 



1 




m 



CarboaSfe of |>on).li deoompewfl mnriatt of linam, I 
and pan of the carbonic add combuin wittt luta 
and tendtn it easily soluble in actd* rhouirb drici,J 

Ciibunaie ofarnmonTaoccaiioikS a precipiiuc, gj 
ii mnsily diMolved by adding more coiboBUv. 

Fiuitiaic of racrcury produce* sn abundmp 
laic, which is solubtr ia muriatic acid j and whK^q 
aequcnilf it not miiriaieof metcury. 

A plalcof zinc, introduced inia a aolution of n 
of zirconia, occasion* a alight cflerreacence ) ibcEj 
I bccoiBci milky, and in a few daya atiumei the fii 
« whiteaemitransparent jelly. 

Alumina decomposes mtuiate of zircoaia with d 
atslance of a slight heat ; tlic alumioa diuolvd, d 
ifjuor becomes milky, and assumca the form ofajj 
When the muriate contains iron, it remains in thc^ 
tioo, and the precipiuied xirconia is quite pore, 
then, is a method of ftectng zircooia from iroa *. ] 



Such are the ptopcTtiet of those murtatenhatm*. I 
kible in water. No alkaline or sanity mnriite it t 
present known that is ioioluble in that liijuid ^of 0( 
the second division of this genus does not exisL 



The following Table exhibits the aolobtlity of At 
murTtatesia water and in alcohol, and the propoct>«saf 
the constituents of each, selected &oai the analjrtis ibt 



stciQS best entitled to conSdeocc. 




■to of 


SolnbihtT 


Saluhility 
Alcdiol. 


Alcohol. 


Coi.«liu..-n:! 1 


Acid. 


Bi-e. 


•■■"■ 


noDia 


3o*n 


1-5 


•834. 


100 


33 


18 

99' ^^ 


nciia 


151 


50-0 


■en 


100 
100 


89-8 
114 




35-46 


0-5 


•834 


14 


t 


400 


IQO+x 


-800 


100 


iie-3 




8h.... 


33 


0-38 


■834 


100 


185-T 




itian 


150 


4-16 


■796 


100 


210*2 


233 


tes... 


43 


0-00 


•"96 


100 


314^5 


87 
135 


nina 


400 


50 


•T96 


100 


lOO 


ia.... 








— 








•ilia 




— 










Chip 1 



hat have been hitherto applied to any useful pur- ^''"'* 
. The following arc the most imporlani, 

Mmriate of potash. This salt is employed by the 
[i-DtiakcTS to procure the cry stall izai ion of alum, . 
is prepared from the waste leys of the soap-malLcrs 
hat purpose. 

I. Muriate of aoda. This is without doubt the 
t valuable of all t)ie salts ; the uses to which it is 
ied are too numerous to be detailed here, and, he> 
i> they are very generally known. 



>M SALTS. 

n**^ 'tit ^* * teuoneir of food it Bcrmi lo be tlmoit nuitf 
- yi — ^ to health, like inliabttants of mwitimr djwkiiai 
too eaiily supplied with it to be sensible of iunl«j 
but the vase it vctt diSereot in tlio«e oouoiriei duiai 
tt a diitaocc from the ocean. Wherever it ii bnl't 
tlie toil of llic inland parts of America, ihitbcr A 
wild beasts resort in multitudes. Thrj appJj Ai 
tongues to the imptegnaicd earth, and gather u wtd 
H will aati»fjr their wants. These places are qfla 
fieii by the Anglo-Americans. So ea^r arc iha 
animals to obtain sail, that they will suficr ibemaln 
to be caughi rather than Icsve the spot *. 

It is needless to mention the great constmptioa I 
aalt in order to preserve animaJ food frotn pDtre&dB 
the application of )i to the glazing of pottcrj, ta|| 
the preparation of leather ; the use of it in atctaSitin 
in purifying oiU, in aOap-making, uul a bondred gAi 
arts. 
Utthc-Jt M ^" uliliiy in chemistry is equally extensive. Fw 
it alone are munMic and osymuriattc acidi obtaisd 
and from it also, of late, ^reat quantities of sodafeii 
been extracted, and iniroduced with advantage Mil 
Kittite for the soda formerly obtaioed from the oa^| 
ttoa of vegetables. ' 

The ncid is easily extracted from this sail by nca 
of sulphuric acid : But to obtain the alkali U a cha 
rate is not so t;asy. The methods which hav« i 
sycceedeil may be reduced lo two. 

1. Mnriaie of soda is decomposed by as 
subsunce which has a stronger afGatly for n 






• S«c Kil. Alff. n. fj. 



I thirgr. 



MURIATES. 3 

ihan soda has. The soda by this process is set at. Chiji, i 
ty, and msy be obtained by evaporation and crys- 
Eation. Baryies and potash would answer this pur- 
complelely ; but unluckily these bodies cannot be 
Attained sufficiently pure, except at an expence which 
iludes ihcir employirient. There are, however, 
substances, which are also capable of setting 
t base of common salt at liberty, and of furnishing 
da^ cither pure cr in the state of carbonate. Thete 
; iilbarge, lime, and iron. 

When about four pans of litharge and one of com- «- Bj- 11. 
Ml salt, properly pounded and mixed, arc macerated 
« little water for several hours, and stirred repeated- 
y, the muiiaiic acid gradually combines wiih the ox- 
de of lead, and forms a muriate, while the soda is left 
n solution, and may be cibiained separately by filtra. 
ion and evaporation. The decomposition goes on 
itill more rapidly if the mixture be heated during the 
)rocess. 

The fact, that the red oxide of lead decomposes mu- 
iate of soda, whiclt was first observed b^ Scheele, has 
[iven occasion to much speculation among chemists. 
"Mr Hassenfraiz endeavourtd to account for it, by sup- 
posing that the oxide is combined with carbonic acid, 
and that therefore it is a case of compound affinity. Mr 
Caraudau has proved that carbonic acid, instead of pro- 
noting, impedes the decomposition ; and that, in fact, 
carbonate of lead is incapable of decomposing muriate 
of soda. He concludes, therefore, that the phenomenon 
cannot be accounted for by the commonly received laws 
cf affinity '. Vauqueliii has proved more lately, that 



the decomposition by meant 
provided the ^juintity of that 
of common salt j that the 
submuriaie of lead totally insc 
• is not decomposed by alkalie 
decom poll lion to the attractii 
an excess of oxide *. But tti 
pletely for the decompositioR, 
oxide of lead has a weaker aQ 
soda has. Berthollct haa at 
rent anomaly by proving,' thi 
mixed with a third, for wbici 
divide it between them in pre 
the quantity of each : And il 
one of the»e subtt&nces with i 
Bubiiance combines with the 
and takis it completely Anoi 
insoluble compound being in 
themixmre, the decompositit 
again a% ai first after every ^ 
oxide of lead and muriate of 
tlie oxide atid alkali divide i 
them, so that some of the co 
and some muriare of lead for 
mixture. But this being in 
altogetlicr insolublci separate 
ju consequence of which a ne 
acid between the oxide and t 
this continues, provided the < 
ficter.t, till the coniffioa salt i 



MDSIATES- $9* 

the alkali may be extracted from commott salt Ch»p. m. 
;aieans of lime, maj be considered as a fact for which ^ lij lune. 
are indebted lo Scheele. Cahausen indeed 
bad hinted at it in 1111; but his treatise had been 
lbrgott«n '. Schecle ascertained tliat a ini:<lUTe of lime 
ud common sair, formed into a paste, and placed in a 
noist cellar, was covered with an elHorcscence of soda 
in 15 daysf-. in I'SS Morveau and Cainy procured t* 
^lenl from the Fnncli government to establish a ma- 
mfactory at Croisic for extracting soda from common 
i>It by means of lime. Tlieir process was exactly the 
Hune with that of Schecle, only upon a larger scale. It 
Iocs not appear, however, that the manufactory was 
Ever established. Berthoiltt has rendered it probable 
that the soda which is Hund abundantly on (he west of 
Egypt, is formed naturally by a similar proctssj:. 

To Schecle likewise we are indebted for the disco- 3-Byir«fc 
rery that common salt may be decomposed by iron. 
Be observed that a wooden vessel placed in a cellar, 
knd containing brine, had its iron hoops covered with 
ka efHorescence of soda. This induced him to dip a 
plate of iron into a solution of common salt, and to sus- 
pend it in a cellar. After an interval of fourteen days, 
be found his iron incrustcd with soda J. The same de- 
kCeroposilion takes place also if zinc or copper be sub- 
jRitUted for iron ||. 

The second method of eslracling soda from com- 

lOn salt is Ic-s direct. It consists in displacing the 

acid by means of some other acid, which may 



• See fait HiiwHlm. 



be afterwards c»ti\y decompottd or dlipUccd in w 
thus the soda i% left behind at U*X in a nstc cf p 
Ttic acids which have been made cboi<:c of ate thcid 
: and the acetic ; the boracic, phmplionc, a 
c acidt might indcrd be cmplDvcd, as iierit 
compote common salt in a high icm[icmufc. 
products in ihu case would be borate of soda, oi t 
phosphate, or arscniaic, of the same bate, acoacdia(fl 
the acid. These &alts toight be aftenKiudtdi 
by means of hme, and iLe soda obtained separaie. ] 
these Hcids urc a gicat deal too high priced lo ai 
tbcir employment. 

Sulp>iuric acid may be either employed in a m 
state, o( HI contbinaiion with bases, when ttte saJtivWk 1 
it then forms can be procured at a sufficiently cbop I 
rate. Alum, sulphate of iii»c, and solphaie of ii 
hare been respectively employed scilh advBntS{;c tg 
decompose common salt, and obtain sulphate of h^l 
Alum is said to have been first employed for that pti- 
posc by Cousiantini, a physiciao of Mellc, ncuOiu- 
butg, about 1750. Tlie proceas, ii is afiirmcd, does Kt 
ftuccccd except at a low tcnipctaiure *, Sulpfian of 
lime decomposes cotrmon salt when farmed wiib it ioit 
balls, and exposed to a strong heal f. Much dttc>it> 
sion has taken place among the German chcmiiHabtal 
the possibility of decomposing common salt by i&eui 
of sulphate of iron. That sulphate of soda maj be cb. 
tained by exposing a mixture of these iho salts loi 
Strong hedt, was Grit announced by Vandcr Balka> 
Tbti was contradicted by Hahneman, but confiimed I) 



• J»r, Jc ATn. Ho. iii. f. $!• 

t M tUtcibc ud AAcan, <ta. * CH» ak. 



MOXfATES. 



Iiperipicntsof Tulleii*, Liel»ltii.-f, inid Wieghbt- 
ccecded commie ir If witli ilic tre^icli cociniissiunctf, 
•X^ievTc, Pellcuer, LurcLt, sua Giruud. v lio were ap> 
^inicd in l~&4 lo cxamii.c ilie d^ffortiit pn.cesKs for 
obuiiiing soda ii<.'n> (.onrnroii mU. liny uteriaiDcd 
fldso ihui pyiiics oi su^i-c^iiliihuret of iiou ma^ be em- 
ploj^ed foi ilie same puipoic j. 

After obtaining itie iiulph uc of soda, il is necessary 
to expel Uic acid in order to produce the soda &epai alelj . 
^Elis is accomplished hj calcining the salt mixed with 
m certain portion of charcoal or of pit-coal. By this 
process it is converted into sulphuret of sc-da, and the 
sulphur may be abstracted bj ihe intervention of iroa 
or ciialk. When the sulphtuet of soda is nearly in 
Ju%io]i, small bits of iron (the parings of linplate aiiswcr 
be^l) hje thrown in gradually in suHicient quantity to 
decompose the sulphuret. The fire is raised till the 
mixiuie melts. The sulphur, having a stronger aSinity 
( for the iion, combines with it and leaves the soda, 
which may be separated by solution in water, filtration, 
and evaporation || . Carbonate of lime may be employed 
also for th^samc purpose U". 

Some G he mists have proposed to decompose common 
salt by means of acetate of lead, using either the ace- 
tate of commerce, or one formed on purpose, by conO' 
bining litharge with the acid liquor obtained by distil- 
ling wood. The acetate of soda formed by mixing 




» Cn\ytA"uili,ngo. 0.^06. t Ibid. J 

t Ibid, I793> ■■ l°4- i ^™- '' 

I Allun, A-i. dt Ciia. xix. 77.— The jracta w 
bflbr. So. Jur. A Mim. No. lii. f.ij. 
^ l.cl>bi.c, ^Im. A Okm. liz. 61. 



aim.lix.st- 

I ducovcicd \>J Mil- 



CO 2 SALTS* 

Drxik II. common Sait with these acetates i» ai'terwacrd) cuosati, 
in order to decompose and expel ihe acetic acul. Bu 
these salts arc too high priced to be cirplojed «ii 
advantage to extract soda trom commco salt*. 

III. Muriate €if Ammonia • This salt is in scuxde- 
gree combustible. Hence its importance toprevecttbc 
oxidizcmeiit of metals. For manj jears the whole ci 
the sal ammoniac used in Europe was impcned fro^t 
Egypt. In that country the greater part of the foci 
consists of the dung of their cattle iotvaitA iato balls and 
dried. These excrementitious matters seen tocootaii 
muriate of soda, or rather muriate of ammooia readj 
formed ; owing perhaps to the saline matters on whicti 
the animals feed. The soot formed during the ooiDbus< 
tion of this fuel is carefully collected and pot into laigi 
glass bottles, wliich are exposed, in furnaces constructed 
on purpose^ to a pretty strong heat. The sal aafao< 
niac gradually subliniesy and attaches itself to tbe up 
per part of the bottles, where it forms a cake of soom 
inches >n diameter. Though this process was comzmK 
nicatt:d to the Academy of Sciences in i IIU by Lemere, 
French consul at Cairo, it was a consideraBle lime be- 
fore the chemistb in Europe thought of imitatiag it, oi 
of preparing sal ammoniac themselves. The first ma- 
nufactory in Germany wa^ begun by Gravcnhorst ia 
1750 fo Soon after it u as made in France b^ fiauiDc, 
I and in Scotland by Dr Hutton. 

PTcpi.-a- The processes most commonly followed in Europe 



cu)a. 



• For a dctaiLH accotiiit of th : processes of maLfng »«]e folloireW k. 
difiVrcnt coMiitrics the reader \% referred to Brotrnriy'r'i An «/i».»i/^ 
Common Sa't^ and to WatsouS Cb:nu*l E^ayt^ ii, .^t- 



t 



HURIATSS. 

Pbeen, 1. To forma sulphate of ammoiiia; to mis 
1 » ilh muriale of soda ; and to expose l!ic mix- 
ture 10 a heat suHicient to sublime the muriate of am- 
monia. 1 he ammonia is usually obtained by ihe diMJl- 
lation of animal substances, or from soot. 2. To de- 

npo^e louriare of lime by meatis of ammonia. 3. To 
> coDibine niuriaiic acid directly with araniQnia, and to 
Siblime. 

Tbii salt is applied to a great variety of purposes. It 
is from tC rhat pure ammonia is usually extracted. A 
Cunsidciable portion of sal ammoniac is consumed by 
coppersmiths, 6tc. who employ it to prevent the oxi- 
dizemeni of ihe surface of the metals which they arc 
covering wilb tin. Dissolved in ntrric acid, it forms 
K(|ua regia, employed in the solution of gold. It has 
the curious property of rendeiing many metallic oxides 
volatile, and is often used by metallurgists to separate 
I metals from each other. These different melallic^ow/n, 
as they were called, or combinations of sal aiamoniac 
with metallic oxides, were formerly tjscd in medicine. 
Great quantities of this salt were once consumed by 
the dyers, though it is difficuh in many cases to see for 
what purpose. At present, much of ihe sal ammoniac 
made in this country is said to be exported to Russia. 

IV. Aluriatc of Lime, This salt t»'as proposed by 
FourCToy as a remedy in scrofulous diseases ; but it 
does not seem lo have come irio use in this country as 
a medicine. The discovery of Lowiiz of the great cold 
wbich it generates tvhen milted willi snow, has made it 
extremely useful as an ingredient in freezing mixtures. 
X.'^'C same chemist has taught us the method of purify- 
ing alcohulandetberby meansof ii, from the water and 
ilcobol with which they are respectively contaminated. 



V. Marittit of Barytes. This lah liss beta n 
mcadcd Bi a cuic for scro^toiu diwrden. Tbe i 
is from live lo twenty drops or mure. Care ovg 
be taken not to use il in too great quaniitici, u, h 
other barytic &al(s, it is poijonous. 

In chemistrr it i* much employed ■* m rewtiTC Id J 
Icct lh« prCKHce ol Hilpfauric acid. When dropi ii 
B liquid holding that acid tn soltilion, an insoluble pn^ 
viptutc of sulphate of barytcs immediately appan. 
BergtDBD intottos tn that this precipttHic is liiible 
when the acid amounts only (o O-0009 of the U^cJd. 
Even when only O'onoop of sulphuric aetd is prcKni, i 
alight cloud appears in a few minutes after dropping is 
the muriaic ". 

The olh^r muriates have scarcely been brotlgbt iota 
common um ciDier in cheinisiry or the aris. 

GzNDs n. Flitates. 

TuESI salts were first made known to the world bf 
Scheele in J'iTl f ; and succeeding cbeniist* hare d 
little more than repeat aad coufinn hit rx|>rrimei]tt. ■ 

Fluaiea may be distiiiguiihed by tbe following p 
perties: 

1. When sulphuric acid is poured apoo tb«m, ihtj 
emit acrid vapours of fluoric acid, which have the pro* 
perty of corroding glass. 

S. When healed, several of them phosphofESOe. 

S, Not decomposed by heat, nor altered by comSfl 
tlblci. 

4> ConlHne readily with silica by mcaas of but. 



edon 
cpro» 



* tcrgaoB, i, lOO. 



4SclHirIc,i.s6. 



PLOATES. <505 



Most of them are but sparingly soluble in water ; Chip. in. 
but their properties have been bat imperfectly exami- 
tied. 



^.1. FluaU of Potasb. 

This salt is most readily procured by fusing in a pla« 
timim crucible a mixture of fluor spar and carbonate of 
potash. The mass, digested in water, yields a solution^ 
^hichy filtered and evfiporated, leaves fluate of potash. 
It has scarcely been examined. 

According to Scheele, it does not crystallize, but 
forms a gelatinous mass almost without taste, which at* 
tracts moisture from the air. It dissolves readily in wa- 
ter. When exposed to the fire it melts without any e« 
buUition *• 

Wenzel says, that it forms crystals when free from 
all admixture of siliceous earth f • 

5^.1, Fluate of Potoib-and^Silica. 

When fluoric acid is obtained by the common process 
in glass vessels, it is always combined with a portion 
of silica. If into this impure acid a quantity of potash, 
or the carbonate, sulphate, nitrate, or muriate of that al- 
kali, be dropt, a gelatinous precipitate immediately ap- 
pears, which, when dried, becomes white like chalk, 
and separates into small loose grains like the sand of an 
hour-glass. This powder is a combination of fluoric 
acid, silica, and potash. Its nature was first ascertained 
by Scheele. 



I. SOLVRLC 



♦ Srhcck on FJu$r, I a6. f Gr«i*i HamStuBf I 531, 



iftOl 



Ii Ihs aa add taste, and is soluble In aboat 150 pu 
nf fauilxBg water ; bat is again partly deposited as i 
■nittt^fm cools. When strongly heated, it melts imi 
ixaBCparent glass, and loses its acid *• 

Mr Scheele has shown, that a similar triple nbiB 
be fanned bj using soda, or the sales conuiniog » 
astead of potash. 

Lime also is capable of combining with these tri 
mlt% and forming with them quadruple salts, compo 
•f iooric acid, silica, fixed alkali, and lime f. 

Sf. 3. Fluate of Soda. 

Tbu salt maj be formed as the fluate of poti 
When the solution is evaporated till a pellicle forms 
its surface, it jiclds on cooling small cubic crystal 
fsate of sods. These crystals have a bitter and ssti 
gent taste ; they do not deliquesce in the air, aad 
but sparingly soluble in water. Before the blow-f 
ibey decrepitate, and roelt into a transparent globule 

Sp. 4. Fluate of Ammonia. 

This salt may be obtained by applying a suffici 
heat to a mixture of sulphate of ammonia and fluorsp 
Fluate of ammonia sublimes ; or it may be prepared 
saturating fluoric acid with ammonia. The solnti 
yields by evaporation small crystals of fluate of amo 
nia. When heated, it sublimes in the state of a sap 
flaate. 



• Schcek, Crell*s Am^^ i. S14. EqgU TkantL f Fbid. 119- 

% fannnjt iii. 306. 



FLUATCS. 607 

Sp. 5. Fiuate of Alumina. .^^^' "^ 

This salt does not crystallize ; but assumes, when c& 
V'aporAted, the consistence of a jelly. Its taste is astrin- 
gent, and it contains always an excess of acid. 

The fluates of yttria^ glucina, and zirconia, have 
not been examined. 



5^. 0. Fhmte of Magnesia. 

This salt may be formed by dissolving carbonate of 
magnesia ia fluoric acid. The salt precipitates in a 
gieat measure as the saturation approaches. 

It is not soluble in water except there be an excess 
of acid% In that case, by spontaneous evaporation, it 
forms hexagonal prisms^ terminated by a low pyramid 
composed of three rhomboidal sides. 

These crystals are hardly soloble in water. Alcohol 
dissolves a small portion of them. Heat does not de* 
ciompose thetn ; nor are they decomposed by any acid*. 

Sp* 7* Fiuate of LUne. 

7\li8 salt exists abundantly native4 It is from it in- 
deed that fluoric acid is always extracted. 

It is found frequently crystallized. The primitive 
form of its crystals, according to Hauy, is the octahe- 
dron, but it occurs more frequently in cubes ; soaie- 
times the angles, and sometimes the edges of these cubes, 
are truncated. The form of its integrant particles is 
die regular tetrabedcoo* 



•' 



IT. tNtOtCK 
■LE FUl- 
ATCI. 



tl%U* 



Thi) salt h« no taste. lu ipecific graviiy is j-u 
It is insoluble in water, and not altered by expen 
the air. 

When heated, it decrepitates and phospho 

atronglj in (he dark. It.emits tliis light ertn bi 

water, or in the vacuum of an air painp. When Iteji 

hot for some time, it ceases to »hine, and the phoiph> 

r*scenl properly cannot be again restored to it bj mt 

process known, except by decomposing it allogelhttbj 

means of sulphuric acid, and forming it anew. Scbwle 

I ucertained that new>foraied fluate of lime is eqnilli 

' phosphorescent wiib native. The cause of ihiscuiion 

L jropcrly is not well understood. After being bnied, 

I <ie salt, though 't refuses to phospboreace si»f iwm, 

I feas not lost any perceptible weigh', nor it it altcral in 

I may of it* other quatitie*. When strongly beaied, ftaic 

[ ef lime melts into a transparent glass. AccordiogW 

[ Baussnre, this takej place At the temperature of 51* 

9 Wedge wood ". 

When heated with sulphitrie, phospliorie, or ■ 
. ccid, the fluoric acid is drivt 

either the nitric nor muriatic decompose it, a 
to the experiments ofScheele. Tlie fallowing 1 
. exhibits its constiiDCDts according to the n 
^ Malysisbiiherto ntnde. 






16 


t 
324. 


II 

sat 


Acid 
Base 
Water 


57 
27 


G7t 

100 



100 


Total 


100 



Sjf. 3. FUfoli of Baryta^ 

IS salty as BtrgAliti infbfftts us, mty ht fbtmed 
aring fluoric acid into nitrate or mttriatt oif barjtes« 
; of barytes preripitites in -the fom of a white 
^r, which requires ft Considerable p i ro portioo of 
to dissolve it. 

* 

[8 curious compound has been found native lili 
ilandy and described by mineralogists linder tbtf 
of cryolite. It has the appearance of a 8tone« 
colour is greyish white } it has some transparent 
yhen broken its fragments are Cubical. It is sofN 
n fluor spar, brittle, and of the specific gravity 
. Before the blow^pipe it melts. Accordttig td 
alyses of Klaproth and Vau^ttelin it ii Ootnpoied 



C09 



::s 



±safe 



n^t y cwi f i ag , u 533. Hut tailfM It Ytry errooeo m* tc it t#< 
i Schcele; but I cannot 6n<: it in either of tlie diitemtiont on 
dd wrictcB hj that iliiittrioiit diemitt. It if giteo b^ Rirwtn#^ 
quoting Schctle. 
■y toalyds. | tOoprotb, hdiw^i it. jC|. 

si. It. Kt 



Acid ind water 40 «>... 47 

Soda SO 33 



lOO* 



loot 



Sj). iQ. FTuatt c/SSictt. 

Fluoric acid, when obtnined by the uvulftaoB 
in gUis vessels, contains alwiys m portion of silica, iri 
forms therefore in reality a iup«rfluateof that earth. If. 
tbis aolaiion be allowed to reotain for a conudeolH 
time in a vessel not completely shot, it depositee nfl 
btilUant, transparent, ihotcboidal oystats. ThcicFeiv. 
croy hat ascertained to be fluaie of silica. The add 
may be separaied by means of heat, and b^ conccan. 
ted acid. This salt is stolublc in alkalies, and fonu 
with ihem triple- sahs {. The silica which precipiiun 
when fluoric acid prepared in glass vessels is abioibed 
by water, rctaiai some of that acid eveti after it has 
been dried. 

The flnate of strontian has not beca examined. 



I 



Such is an imperfect detail of the properties a 
fluatcs, a set of compounds which have bitliefto atinu. 
ed but little of the attention of chemista. Tlie reccol 
discovery of fluoric acid, however, as a conttitucnl of 
many bodies in the mineral kingdom, .where it was not 
suspected, will no doubt raise this neglected gennju 



] FoUTcrav.iii. ill. 




taOTt repute, and induce some experimenter to favour Cha p. JU. 
the chemiciil world wilh a more complete detail. Kicll- V. 

ter indted seems to have subjected the greater number 
of them to au analjrsis* The fotlotving Table exhibits 
the rmulc of his CKperiments and calculations *■ 

FtoKci (if Add. Ba»e. Crmxitu- 

Alucnina,...i...,100... 193 emicftba 

Magnesia 100 144 **"^ 

Ammonia....... 10O...« ..157 

I.ime lt,0..,.d,,4...,lSQ 

Soda ....10D...4 201 

Stroniian luO 311 

Potash ;..100 316 

Bar/Ks lUO <...520 

_ m.Un«i 

Thb only fluate hitherto applied to any use is the ^'■'"■^"- 
fluaie of lime. In Derbyshire it is turned into boxes, 
candlesticks, and various trinkeis: it is emplojed to fa- 
cililaie the fusion of diflercnt kinds of ores. From It 
all the fluoric acid is procured, to what use soever ihit 
acid is to be applied. 

GKKt;S III. BORAtES; 

TlfOtioa some of these salts have been long known, 
and one ot them has been in gcnetal use for maiiy year^, 
their nature is still but imperfecily understood, because 



* ihiKnnI been 'hie (a procure a n^}"- of RichiTt'a very eiirTUia 
and iinpqrMnt writing on Sirciimiirt, in whichhii sbitmiiuna an ihe 
itwin ir: lu Sc i-und. TI i tibk ii< tht 'en w« cikuliten frani a ihcn 

Rra 



thej btve been 1>nt soperfidi 
u the on)^ cbemitt, if we cao 
tempted s dncription of Ibea 
gnnhed bj the following pro 
1. Before the Mow-plpe ll 
2> When tbcir concentrate 
snlphnric aod, and allowed ' 
boractc acid are deponted* 

3. The^ areaot altered bj 

4. With noil BetalUc oxi 
and form globule* of coIoium 



Of. 1. Bonn 

This ult, which wu fint 
little known. It maj be pn 
tnre of boradc acid and nitre 
nitric acid, and leevet ■ wbiti 
diMolved in water, yicldi try 
four- sided prisms. It is cap 
excess of hzic, and formin 
From tiic experiments of We 
constituents secmi to be *. 

Acid 

Base 

Sp. 2. Bora. 

This «!t, which may be f 
with boracic acid, has ntver 



k -x 



18 US, that about half itt weight of boracic acid is 

teuary to saturate borax*. Its specific gravity is 

t*S51 1- It is soluble in 2-5 of water at the tcmpcra- 

k(ture of 147° t- From the experiments of Wenzel, the 

Ik^oporlion of its coast it ueiits seems to be J 

Acid IQO 

Base ii 

Sjt. 3. Sorax er S»t>-bornli */" Sotta. 

Tuts salt, the only one of the borates which has been ' 
accurately examined, lb supposed to have been known 
to the ancients, and to be the substance denominated 
tbryiocoila by Pliny. At any rate, it is mentioned by 
Geber as early as the ninth century under the name of 
iorax. Its composition was tirsl pointed o«l by Geof- 
frey in 1732, and Baron in 174&-. Bergman was the 
first who demonstrHied that it has an excess of base, and 
is therefore in the state of a sub-borate. 

This salt is brought from the East Indies in an im- 
pure state under the name of tiatal, enveloped in * kind 
of fatty mailer, which Vauqueliu has ascertained to be 
a soap with soda for its base. When purified in Europe, 
it takes the name oi borax. The purification is per- 
formed by the Dutch ; but the process which they fol- 
low is not known. Valmont Bomare infomis us that 
they extract to parts of pure borax from loo parts of 
tinkal. The operations are conducted in leaden vessels, 
and consist chieHy in repeated solutions, filtrations, and 



1 



* Boxman, iii. jlj. Accoidiog to Withering, twice ici weig 

— Bcrgnun't Siiagrafiia, p. sA. Eog* Tnin. 
f HaMcnfralt, Ant. A Ctim. tiTiii. 1 1. 
1 WdlMl.Ibtd.p. ^03. ( frrtraritictaft.f. U^. 



014 8ALVB* 

Book n. crystallizadons, Valmont Botnare tntpectf Ait faj 
»— ^^ * employ lime-water; and Fourcroy has shown thattKi 
might be useful in decomposing the soap in whidi tnk 
borax is enveloped ^. 
fropcrtiri. BorajL, thus purified, maj be obtained crystaDiidii 
hexangular prisms^ of which two udes are much ImL 
er than the remainder, and terminated by triangular pj* 
ramids, Ii is of a white colour. It$ spectre ^rtfitjii 
1*740 f. It converts vegetable blues to green, b 
taste is styptic lAud alkaline. 

It is soluble, according to Wallertus, in 20 tiflKsin 
weight of water of the temperature of 60% and six tines 
its weight of boiling water. 

When exposed to the air it effloresces slowly sal 
slightly. 

When heated, it swells, loses about foorvteoths of ill 
weight, becomes ropy, and then assumes the form of t 
light porous, and very friable mass, known by tbenaas 
of cabimid borax ,- in a strong heat it naelts into atnos- 
parent glass still soluble in water. 

When two pieces of bofax are struck together in the 
dark, a flash of light is emitted %. 
p4)mppfi- 'jThis salt, according to Bergman, is composed of 

^ 89.cid 

}7 soda 
44 water 



100 II 



♦ Fourcroy^ iiu 33a 

f Ktrwan. Wallcriuc makes it 1720 {Cheimutry^ p. iA6) ; Dr Wat. 
5on, I 7J7 (K.'/n/, v. 67 .'. 
I Accpnf)» Nic})oUop*t /mtt. ii. a8. Bcrgman't DOtet 00 Scbcficr. 



r 



Sf. 4. Boralt of jlmmonia. 



*■ This salt lias been described bj Wenzel. It forms 
^ JMmianent cryslnb, which have a considerable rejein- 
P falKiice to borax. When healed the ammonia flies off, 
^ carrying with it a portion of the acid, but leaving a 
F' pan of it in a slate of purity. From tbe experiments 
^ «f Wenzel, its constituents aie * 
fc lOti BCtd 

^ 34 base and water. 

1^' Sp. i. Borate tf Stroatian. 

This salt has only been formed by Dr Hope. It is 
a white powder, soluble in about 13U parts of boiling 
' water. The solution turns the syrup of violets green t- 
* It it therefore in a stale of a sub>borate. 



Sp. 6< Borate of Magnesia. 

BCKOMAV formed tliis salt by dissolving magnesia in 
fcoracic acid. The solution proceeded slowly; and on 
evaporation, the salt was precipitated in small irregijlar 
crysuls. It is soluble in aceiic acid. Alcohol decom- 
poses it. It melts easily in the ilre without being de- 
composed X' This salt has been found native in the 
mountain of Kalkberg near Luneburg in Germany. It 
was first analysed bj Wcstrumb in 1188. 



• f'erutm/i'iba/i, p. 149. \ Hope, £^w. TrJ^ iv. 17. 

] Bcrgnwn, i. jSC. 



^^1« 



It ii in (he form of traa^parent or opaqoc nhkUayt> I 
taU, coiisiiiinft of cube*, ).>vttif[ ibrir cdgn andEeoi^l 
lb«tr aDj{le!i trunc-itcd. ll ift to hard a* to Kiaidi 0»aM 
and lo ktrike fiie with kieel. lis specific p»itfil 
3-3(J6. Wlicn heated, it becomes electric ; and, *^M 
» singular, the truncated aagln we alwajri pwtn^l 
elrctric, wliile (he oppoiiie entire one* «re negatiic*. 

These crystals are insoluble in water, and not il 
by fXiiOiurc lo the air. When healed, ihejr d 
tale: in a red heat they lose thair lustre, bai i 
■ensibly dimmish in weight. In a while heal ll 
0"i03 of iheir weight. When cxpoied to ihe 
of a very violcnl heat, ihey melt into a ycllow.C 
glass. 

According to Wcatramb, (hejr ore composed of 

73*5 acid 

li-6 magncsift 

11-g hme 

lOO'O 

Hence the salt was considered as a triple compon 
of boracic acid, lime, and magnesia ( but Vauquelta ^ 
shown, that ihe lime is foreign, and that the mincnl i 
boraic of magnesia f. 

Sp. 1. B«raU of Lime. 

This salt may be formed by mixing together lin 
inter and the aqueous solution of boracic add, or \ 
boiling together lime and pare borax in water. In d 



• Ktujr. 4nt. 4l Ciim il. J9, 



Ctt$e, the borate of lime precipitates in the state of 
while powder, tasteless, and difHcultly soluble in 
wrBter". 

Sp, 8. Borate of Baryta. 

Alt in»Iuble white powder, which has scarcely been 
examined, formed by the same process as borate of 
lime. 

Sp. 9- Borate tif Alumina. 

a This salt may be formed by mixing together the lo- 
ladons of borate of soda and sulphate of alumina. It 
is said 10 be scarcely soluble in wster, and not to crys- 
tallize. 

When boracic acid and silica are exposed to a strong 
heat, they melt together into a Iraospareni glass. This 
compound has received the name of horatt oftilka from 
Fourcroy. 

The other borates arc unknown. 



The only salt belonging to this genus that has been 
applied to any useful purpose, is borax. It ts some« 
times used in medicine as an astringent. It is used as 
a floxformeials, and enters into the composition of some 
of the coloured glass pastes made in imitation of gemsj 
but Its great use is to facilitate the solderiag of the more 
precious metals, ll is employed also as a Sux by mi.. 
neralogists in essaying the properttei of mineraJs by the 
blow-pipe. 

* Bcrpnu, iii. 3fij. 



" 



m.UtM 

Borates. 



Gemub IV. ] 



This clau of talts was fin 
MargraC Several of the p 
euunined b; Haspt *, Scfalo! 
Wewrunib and Scheele { bat 
count of them we are indeb 
quelin. Thejr may be diadi 
propertiec 

1. When heated along wi 
Dot deeompoiedt iwr U photp 

2. Before the blow'pipe 
globale of glasit which ia ui 
othen opaque. 

3. Soluble in nitric acid v 
prectpUated from that aelutioi 

4< Oecompoied, at lent pa 
and their acid, which is aep 
charcoal and heated to rednesi 

5' After being strongly he 
resce. 

The phosphates, like the si 
with aa czcvss of acid, and U 

The phosphates at present I 
of which are triple salts. So 
different states, constituting vi 



• Di Sah Min-iiii Prrljli, IJ40. 

j, In rhe dcKripiioD of the phoqitu 
woAi. ihcf ban betn cuufounilcj with 
guidrd bj ibe eiperinmcf o( Vinqueli 



I'^w 



FIIOSFHATES. 



Sf. 1. Phosphate of Potash. 

\t this salt there are two varieties: The first, which 
Is in reality a sufrr^hosphate, was first described by 
Margrair in 1740 ', and distinguished froai the phos- 
phate by Lavoisier in 1774> The second, which is a 
neutral salt, was also noticed by Margraff in 174(J f, 
but its constituents remained unknown (ill ihey were 
lately ascertained by Darractjt. 

Variety 1, Superphosphate. This salt may be pre- 
pared by dropping carbonate of potash into diluted 
phosphoric acid till all efTcrvcscence ceases, and then 
evaporating the solution. It crystallizes with great dif- 
ficully into striated prisms ; assuming more readily the 
fortn of (a jelly, and when the evaporation is carried 
farther, becoming dry altogether. Its specific gravity, 
when dry, is 2'851(ij. It is exceedingly soluble in 
water ; and when dry readily attracts moisture from 
the atmosphere, and is converted into a viscid liquid. 
When heated, il fir^t undergoes the watery fusion ; then 
allows its water of crystallization to evaporate, and is 
Deduced io dryness. In a high temperature it melts to- 
to a transparent glass, which deliqueaoes again when ex- 
posed to the air. 

Variety 2. Phosphate. This salt may be formed by 
nixing together superphosphate of potash and pure pot. 



throughout Indeed there i) «rong reaten to iiupect, (hil the diffi-renc 
ttciwecn (hoe >wd genen nf alti dependi more upoa uher circuuutan 
f.a tbin upon the lulure of the add. 

* C^K. i.S4. t Ibid]>. l6x \ Ant. it Cii'n. iL S7A. 

I HuMnlTMi, An. A CUm, uvlil. i» 



ash, nnd exposing tliemtoaiircng beat in i platinum ot. 
ciblc. A white coloured mbiixnce is obtained, « 
ii the phosphate in question. Or wc may boil my d 
the alkniine supcrphosphaiei in » tolutiun of |kmA 
A while powder falla, which ii the talt vnwud. By 
thii lust pcuce&B it wat procured b^ Margnf. 

The phosphate of poiaili is tastelest and tnwlnUci 
cold water, but loluble in but water i and it [ 
as ihcaolution cools in a gritty pouder. Iliicxntt 
ly fustible i roelting betoie.the blow-pijic into ■ Ua 
parent bead, which becomti opaque on coolio);. |(' 
soluble in niiric, munatic, and pho«ph&nc aciih; 
solutions ate ibick, giuiini>a3 and adheaive. Wtaa 
sufficiently diluted, the alkalies occa&ioo no prcdpta 
til these solutions ( but when ihcy are con centra ted, 
piccipitatt appears. 

According to ihc analyst* of Sauuure junior, iitcrat 
position is as follows i 

acid 35 

base 05 



This sail has the property of comhtnmg. Hid of foronEB 

a triple insoluble compound with 1 

Sp. 2. Plwphatr 0/ Soda. 

This salt exists ready formed in urine, and was iIb 1 
first known of all the phosphates. It acciipTed a good .{ 
deal of the attention of chemists ; and the difficult of I 
analysing it gave occasioa to various hypotbcKl c 




niosrsATKs. 

centing iis nainre. Hellot remarlced it in urine ; and Ctup. nt. 
deicribed il, in 1737, as a salt different from those that 
liad usually been observed. Hanpt described it in 1740 
under the name of sal niirabi/e pertatutn, or " wonder- 
ful perla'cd sail." It was called ptrlatid fronn the 
grCf, opaque, pearl-likc colour which it assumed when 
melted by the blow-pipc. Margraf examined it in 
t 145, and found it would not yield phosphorus wh«tt 
treated with charcoal as the other salts of urine did, but 
ascertained thai it contained phosphoric acid. Roucllc 
the Younger analysed it in mo ; and concluded from 
his expert menis that it was a compound of phosphoric' 
acid and soda •; but Mr Proust, being unable (o ob- 
tain phosphnnii from ii, concluded that its acid wb» 
not the phosphoric, but another analogous to the bora- 
Bicf. To this substance, which Mr Proust actually 
cbiained, Bergman gave the name oi frrlated acid, and 
'Morveau afterwards called it ourttic acid. But Mr 
Ktaproih soon after analysed it, and proved that 
it consisted of soda lupersaiu rated with phosphoric 
acid t- Schecle soon after made the same discovery J. 
The acid of Mr Proust, then, is merely phosphite of 
soda combiited.wiih phosphoric acid, or luperpbotpbate 

Dr Pearson, who introduced it into medicine as s 
purgative, gave the following process for preparing it: 

Dissolve in a long necked matrass 1400 grains of P«pK*- 
crystallized carbonate of soda in 2100 grains of water 
»t Ihc temperature of 150". Add gradually 500 grains 






t Ibid, a }&;. 



of photphofic acidof ih« specific gr&Tily I-SS. Bdl 
the liquor for ionic minutes ; and while it u b«l'ui| 
hot, Altralc ii, and pour it into 2 shallow vessel. Lfl 
it remain in 3 cuol place, and crystati will cootiniu u 
form for several days. From the «bove ^uaalitiei «f 
niaieriaU he has obtained from 1450 lo 1550 gtuMd 
cr^atals. Apothecaries oniatly prBi»an it from llic»< 
pcrphatpliue of liiDC, obtained from bones bj incaai rf 
sulphuric acid. Aii excess of curbouaie of sods i»td< 
dcd (o separate the lime- The liquid it then Sltaol 
and evsporatctl slowly lill it cr7stalli31.es. 

lu crystals are rhoinboidal prisois^ of which the a. 
cute angles are 60°, and the obtuse angles I20', w. 
minated by a threc-»idcd pyramid. Its specific gniisj 
is 1*333 *- Its taste is almost the same with that of 
common salt. It is soluble at the tnnpcraiure »( ttf 
in about four pans of water, and in two pans of boiIii[ 
water. This solution cry^ullizes oa coolings but, ii 
order to obtaio the salt properly crystaUizcd, the solo, 
tion should cont^iu a slight excess of alkali. Wha 
exposed 10 the air, this salt very sooti cffioresces o 
siirfsce. When lieaied, it undergoes the watery fn^ 
At a red heat it tnctli into awhile enamel. BefMi 
blow pipe it mclls into a tranapareut globule, will 
becomes opaque on cooling, and its lutfscc aequitaifl 
polyhedral figure. 

It is not altered by combnstiblei nor metaU. WiA 
.metallic oxides it enters into fusion, and fom» s colour, 
fd globule of glass. Sulphuric, nitric, and 1 
acids, decompose it pttnially, and croDTcrt it inio n 




PHOSPHATES. CSl 

'*to*phaie of toda^ In this stale it is more soluble in Ch»p. m. 

:r, and not so easily crystallized ; but may be ob- 
tained by proper evaporation in the state of thin scales, 
!not onltke boraoic acid. It was this superphoipbaie 
vrhich Proust obtained, and which be coniidered as a 
peculiar acid. 

The greater number of earths may he fused along 
With this salt, and converted into glass. 

5"^. 3. Phosphate of Amtnimia. 

This salt also exists in urine, and seems to have been 
first accLiiately distinguished by Kouelle. It was af- 
terwards examined by Lavoisier in 1774) and still more 
Jsiely by Vauquclin *. It is usually prepared by sa- 
turating with ammonia the superphosphate of lime ob- 
tained from bones, and evaporating the solution to such 
It consistency, that when allowed to cool the phosphate 
•f ammonia is obtained in crystals. 

It crystalliies in four-sided prisms, terminated by Pr«p«ii*». 
equal-sided pyramids. Its taste is cooling, salt, and 
ammoniacal. lis speci^c graviry is rB05lf. Ii is 
soluble in four parts of vuRler at the temperature of 
, and in rather a smaller proporiion of boiling wa- 
it is by spontaneous evaporation that it is obtain- 
ed in the stale of regular ciystals. It is not altered by 
exposure to the air. When heated, it undergoes the 
watery fusion : it then dries ; but if the heat be conti- 
nued, it swells up, loses its alkaline base, and the acid 
melts into a transparent ^lass. It is the only one of 
the earthy and alkaline phosphates which can be decom* 



• /w. it fEaU Ptlytnh*ifrt. 




pnKcI by hnt : hence the reason thM it yicldt f 

phorui wliei) distilled ilong with charcotl. 

It ii decoinpose<1 by the sulphuric, nitric, tndff 
lie Rcidi, and by iho lixed alkalies and alkaline a 
It it capable of combining with »n additional deK#^ 
acid, and of passing into the state of a supcrpbotfbtt. 

Sp. 4. tboipbate of Magfteiia, 
This salt was first formed by Bergman io \Tii*. 
It has lately been examined with much precision bjifat 
indefuligable V»u<jucliD+. It is usually prepsrtd bj 
dissolving carbonate of magnesia in phosphoric sd^ 
and evaporating the solution gradually till the sail ap. 
tallixesi but it may be obtained in large regular cryslil] 
by a much easier process, lirat pointed out by Fott' 
croy. Mix together equal pans of the aqueous tolt;* 
tions of phosphate of soda and sulphate of magneni. 
No apparent change takes place at first ; but b a fea 
hours large transparent crystals of phosphate of mtgsC' 
iia make their appearance in the solution. 

Its crystals are six-sided prisma, the sides of which 
are unequal. It lias very little taste ; however, it Icim 
a cooling and sweetish impression upon the toogoe. lt> 
specific gravity is 1-5480 J. It requires about 15 p»rH 
of cold water to dissolve it. It is more soluble in txul- 
ing water, but it crystallizes in part as the sabtioe 
cool*. When exposed to the air, it loses its water of 
(l-yslallizaiion.and falls down in powder. Whcnbeal- 



t HuKubsis, Ma. it aim. utiiL 1 1. 



J 



PHOSPHATES. 



i roodeniiely, it is aho reduced to a dry powder. In 
'high teinperalure, it melu into a Iransparcat glass. 



Sp. 5. Photpbate of Soda-aad- 4tm 
TaoUGH this salt, known to chemists hy the oamu 
' imerocoimic lalc and /iiu'htt ia!t of urine, wasexlract- 
M froin urine, and examined much sooner than any of 
le other phosphates, it was long before philosophers 
ero able to form precise notions concerning its nature, 
r even to obtain it in a stale of pnriiy. Margraf was 
X first who pointed out the method of procuring it pure, 
and who published a detailed description of its proper- 
He showed that it contained ammonia, and that it 
yielded phosphoms ; but he did not succeed in discover- 
Ig its whole couitiiuents", Fourcroy was the first 
'Iio gave a precise account of the proportion of its 
hnmponent pans-f . According to him, it is composed 

Itf 3? acid 

Y' 24 soda 

1? ammonia 
25 water 









The properties of this salt are nearly those of the 

Eihate of soda and phosphate of ammonia joined to- ' 
r. It answers better than the first of them as a flux; 
se the beat sooti drives off the ammonia, and leaves 
CSS of acid. Its specific gravity is 1*509 J. When 
id to the air, this salt effloresces, and gradually lo- 



t Am: it aim, «ii. ilj. 
uiiiLtl. 

S » 






ST* in ammoni* i a (act fir« obsefvcd by ihe E 

Chwlnes. Margraf hadobKrvwl ibai tbe »m 
dissipated when the solution of it in water is et»(wa«i 
Sji. 6. Phoiphatt of yJnmoHia'iMJ-Magmnia. 
Tbis ash wM first discovered by Fourcroy, Mb 
CouikI it ia a calcalous concretion formwi in ihcethi 
oft horse. Smoc this discovery, Foorcroy sod Vlfc 
(juelin have observed it »lso in human urine. 

It might be prepared by mixing u^etber solmmid 
ihc phosphates of ammonia and of magnesia in wm 
the wiplc sail immediaicly precipitates in the fciui 
a. white powder. When urine ia aUowed to tmm 
considerable time in dose vessels, it often dcpostti Ar 
salt in rcgulw ciystais oo iJie sides and bollom at d 
resBcl. These crystals aresoiall four.*ided prison, fc 
n)i»ated by irregular four-sidcd pyrsoiid*. This a 
is tasteless, scarcely soluble la water, aad not litUc 
be altered by exposure to the air. When heato^ 
falb to powder, give* out its amraooia, and is ihil 
teiDpcrature melts into a transparent globule. Vb 
distilled along wtih charcoal, phosphorus is eblaioe 
Fourcroy has asecriaiaed that the phorsphatc of ama 
nia-and- magnesia, obuincd from tlie calcaloiuai 
(ions of the horse, is comjioscd of 

33 phosphate of amnuMiia 
33 pboiphate of magonift 
, 3S Wdter 



I'HosfHArrs. 



J/>. 7. Pboipbatc of Lime. h.*th. 

.Or lliis sail there are two varieticB; the first neutral, 

ither a snpersall. 

Variely 1. Photjihatiof Lime. This iDteresling sair, 

htch constitutes the basis of bones, was pointed out 

Scbeele «nd GalM-in m4: but for the first precise 

Bcount of its properties we are indebted to Eckebcrg*, 

^WUcioj, and Vauquelin f. 

As this salt constitutes the basis of bonev, it i> not ptepat^ 
IBBessary to prepare it artificially. It may be obtain- ''°"* 
id in a Slate of piiritv by the following process ; Cal- 
ue the bones to whiieness, reduce them to powder, 
wash them repeatedly with water, to separate se- 
ll soluble salts which are present. Dissolve the 
irhole in muriatic ncid, and precipitate by means of am- 
Dnia. The precipitate, when well washed and dried, 
pure phosphate of lime. 

Ptfti^phate of lime, thus prepared, is always in the Propcrtio. 
Mate of a white powder ; but it is found native in re. 
^lar crystals. In thai state it is known by the name 
«£ apatiu. The primitive form of its crystals is, ac- 
cording to Hauy, the regular six-sided pristn ; and the 
primitive form of its integnmi particles is a ihree-sid d 
prism, who^e bases are equilateral triangles : Bui it ve- 
ry often assumes other forms. It is destitute of taste, 
insoluble in water, and I'ot l:able to be altered by expo- 
gore to the air. It may be exposed to a strong heat 
vithout undergoing any change ; but in a very violeat 



i rCrclr. ^««/., 1798, i. 313- 



SALTS* 

heat it becomei soft, and ti converted into ^ «hiti 
mi trans parent enamel, or ruber porceUin- A«n^ 
to the experinienti of Siussurc, a heat of 3~a" Vi'dft. 
wckk! ii r>eces%ary to produce tliis effect 
in nitric and muriatic acid without cfrervcwma, ^ 
any be again precipitated from them una] tend bjj 
riate of atninonia. 

Sulphuric, nitric, moriatic, fluoric, and 
get&ble acids, are capable of decompe&ing phofpl 
time i but the decompotiiion if onljr partial, im. 
croy and Vauqiielin have ascertained, thai these ui 
are only capable of abstracting 0'40 parts of the liai, 
while tbc remainder continues combined with the jh» 
phoric acid, constituting a tuptrphotphati af limt. Utsei 
the reason thai phosphoric acid is capable also of dccn- 
potiog partially the combination of these acid* kub 
liinci it abstracts ai much of the tinac as it sufficitoiK 
convert it into superphosphate. Tbc constitamit cJ 
phosphate of lime, according to tbc most Kcctmtc isk 
lyscs, arc as follows : 





t 


' 


f 


[1 










Acid... 


30-5 


39 


41 


45 




Bue... 


69-5 


30 


53 


55 




Water. 




25 








Tot.l 


100 


100 


lOO 


100 





• Jmr. it fbj,. x\t. ■^. t Kta(irotb'i Sa*r^. BL Mf 

t EduhcTK. t.'rd|*> AikmU, i;^, i. jii. 

f Pcwrmr aad VMfJtlin. ^ RichMr, £Miff» CMpi.i. vim 



FHOSFHATES. 929 

TThesc analyses do not differ rouch from each other, if Chf. m. 
Swe except the first, which doubtless gives the propor- 
liOD of acid loo small *. 

Varielj 2. Superpbosfbatr of Lime. This variety Prep»ra- 
iwns first distinguished as a peculiar compound in n95 '""^ 
[by Fourcroy and Vauquelio. .It had indeed been often 
formed before, but chemists had neglected to eKamine 
it. It is ihts salt which always remains in the aque* 
aas solution when calcined bones are decomposed by 
neans of sulphuric acid ; and it may be formed artifi- 
cially by dissolving phosphate of lime in phosphoric 
Vcid, till the acid refuses to take up any more, and af- 
lerwards evaporating the solution till the salt crystal- 
lizes. 

Its cryUals are usually thin brilliant [lates, rcsem- Propertci. 
bling mother-of-pearl, which easily adhere together, 
And acquire a kind of gluey consistency. Its taste is 
strongly acid. Water dissolves it, and in a greater pro- 
portion when boiling hot than when cold : hence a sa- 
turated solution of it in boiling water crystallizes on 
cooling. It attracts a little moisture when exposed to 
the air. 

When heated, it readily undergoes the watery fu- 
sion ; then swells up and dries. In a high temperature 
it melts into a semi transparent glass, which is tastelcH 
and insoluble, and is not altered by exposure lo the air. 
When this salt is healed to redness along with charcoal, 
its excess of acid is decomposed, and converted into 
phosphorus, and phosphate of lime remains behind. It 



• KUptntli iaiecA clc'Srhere gin* ilie cooiiiioenu of ihii uit enct- 
hr aj in the liK (olttmo of the table in the tnt- 



ii ^m thii salt that phc 
but the process of Fourcro 
posing the tuperphosphate 
lead, and afterwards decon 
b^ means of charcoal, mu 
portion of phosphorus. 

No acid hitherto tried ii 
salt, except the oxalic, wl 
pletel}', and precipitates wi 
lime: but it is decompose 
phosphate of lime b^ all tl 
It is composed, according 
and Vauquelin, of. ! 



Sp. 8. Phoip 
This salt has hitherto 
Vttuqueliii ". 

It may be prepared eith< 
acid wiih barjrtcs or carboi 
together an alkaline phosph 
barjies. In cither cate the 
pitates immediately in the I 
This salt is tasteless, incr 
in water, and not altered b 
specific gravity it I'^sei \ 
melts into a gre^-coljured 
its component parts is unkn 

t HiMcnfruz, Am 



o. 



FHOSFHATES. 



«n - 



phosphoric acid is dropt inio a solution of ,'^P-"t,, 
■s water, a precipitate of phosphate of bary tes im- 
mediatelj falls ; but this precipitate is redissolved by- 
adding an excess of acid *. Hence it follows, that this 
•■It is capable of combining with an additional dose of 
id, iuid forming a superpbosphalt of bary tes. 

Sp. B. Pbo.<pi>ale of Stroatian. 

This salt was first formed by Dr Hope ; but it was 

ore particularly described by Vauquelio in i~Jn +. 

Like the former salt it may be formed by dissolving 
carbonate of strontian in phosphoric acid, or by mixing 
logether nitrate of stronlian and phosphate of soda. A 
whire precipitate imaiediaiely falls, which is the pho^ 
phaie of strontian. 

This salt is tasteless, insoluble in water, and not al- Profotiet. 
tcrablc by exposure to the air. It is soluble in ar» excess 
of phosphoric acid ; a properly which distinguishes it 
from phosphate of bary tes. Before the blow-pipe it fuses 
into a white enamel, and at the same time emits a phos> 
phoric light. It is completely decomposed by sulphuric 
acid, but by no other. According to Vau(|uclin, it is Compou- 

composed of 41'34 acid 

58*10 strontian 



Sp. 10. Pbojphalt of Aliimn». 
This salt has only been examined by Fourcroy. It 
may be formed by saturating phosphoric acid with alfi- 



• Feurtroy mi V»u^tl'li, Mar. dt CbuHt. a. ll. 
t J<MT. ic Mi*. An. n, p. k}. "^ 



mina. It U * twulcss powder, iasolobl« i 
Unsolved in phosphoric acid, it jrieldiagriujiK 
And ajummjr solution, which \>y licai i* convCTtcda(| 
a tiaosparcntglus. 

Sj>. 11. Phcipbaie of Tltria. 
THfs Balthasonly been formed by VatMinelb. ' 
the sohiiion of phosphate of sixls is mixed wtih ibe ■ 
phate, miralc, or tnuriaLc of ytiria, phoiphaic of ]td 
precipiuici in gclatinou!> iiiikcs ' . 

Sp, 12. Pbcsfhate of Gticiaa. 
Ti)I> salt ha> been examined onlj by V'auquelin. 
obtained it by pouring pliosphatc of soda into the u 
lion of gluciaa in sulpbunc, nitric, or munitic a 
The phosphate of glucina iii in-ccipiiatcd inihc statci 
white powder. It docs not cryMaiii<tc. It i* tatid 
iowlublc in water, unless it contains an excess uT % 
and not liable to be altcnd by exposure lo the 
When heated strongly, it inclls into a transpM 



Such are the properties of the phosphates as 
ve an acquainted with them at present. UilhcrtB 



t Phophoric >dd ud Vilica, when Diii«d Mvgcthcr and cipowd 
ffioag hclt, tnclt Into ■ beinriful uini{<trCTit g\»m, trhicli n not del 
pOMd diher by the «rfton of ici.l, or irf albtic*. Foaranj hu f 
thit conipouDii the nunc «f phaqthiic r\ln\^e^l but Ir ii caniiiillr i 
lent from nltt, ud soght ihertfoic imhcr tt> be ranked i« mK « 



FH0ftPaATS3. ^35 

CWtplftr anal jtis of their cotistitu^ts has been publish. Chap, m. ^ 
«d except bj Richter. The followiog Table exhibits 
the result of his experiments and observations *« 

Phoiphiteof Acid. Bi«e. 

Alumina. ••••« ••loo 63*0 

Magnesia lOO 02*8 

Ammonia. ••• • ...lOO 66*6 

Lime.. ••..•• ••.lOO.. .« .. ..SI 

Soda .' 100 87-7 

Strontian • 100 135*7 

Potash 100 1 C4 

Barjtes 100 227 

m. Uias 

Four only of the phosphates have been hitherto ap. Ph^' 
plied to any useful purpose* »«ati«. 

1. Phosphate of^soda* — ^This salt has been introduced 
into meciicine as a purgative; and as its taste is not disa- 
greeable, it has be<(n much employed. It is usually ta« 
ken in broth, which it is employed to season instead of 
common salt. It may be substituted for borax to pro* 
mote the soldering of metals. Mineralogists employ it 
as a flux when they examine the action of heat on mi- 
nerals by means of the blow-pipe. 

2. Phosphate of ammonia. — This salt is much em. 
ployed as a flux in experiments with the blow-pipe. It 
enters also as an ingredient in those coloured glasses 
cMtd pastes, which are made in imitation of precious 
stones. 

3. Phosphate of soda- and^ammonia, — This salt, like 



• StatU/tte ChmufM^ 1 136. 



"^ 'ill ''" preceding, is ued to e 
V— * pip^t v><I aiuwtt& Rinarica 
rcsdtocis with which it pai 
4. Pbtipialt ofVmi.— 
making capeb ; from it d 
phosphortu cmplciyed by c 
•nplojrtd likewise •&.« ma 

GcHOs V. : 

These s*lt3 have been I 

time, and their propertie* > 

VauqucliD f. Thej inaj 

lowing properties : 

ntten. '- ^ben bested they en 

2. When distilled in a s 
little phosphoms, and are c 

3. Detonate whca h«ate 
of potash, md are cQnTcrie< 

4. Converted into pbospl 
riatic acid. 

5- Fusible in a violent Y 
The phosphites at preset 



Sp. 1. Phatp 
This salt is formed by di 



< The near resemblance bctweec 
{.xiaA me' 10 plate ihrm next tacii a 
porate then in the cable uf ihe irra: 

I hvt.-itt' £.).'< P./i((ttii/gi>E,l. 



PHOSPHITES. .^36 

in pbosphorons acid, and evapoi aring the solution slowly CT-.^r- ^n^ 
till it deposites crystals of phosphite of potash. It crys- 
tallizes in four-sided rectangular prisms, terminatied by 
dihedral sumnnits. Its taste is sharp and saline. It is 
soluble in three parts of cold water, and still more so- 
luble in boiling water. It is not altered by exposure to 
the air. When heated it decrepitates, and then melts 
into a transparent globule, which becomes opaque on 
cooling. It does not phosphoresce so evidently as the 
other phosphites, perhaps becausie it contains an excess 
of potash, which saturates the phosphoric acid as it 
forms. 

It is composed of.. ;3Q*5 acid 

49*5 potash 

11*0 water 



ioo'O 



$f 2. Phosphite ^Soda. 

This salt may be prepared exactly in the same wajr 
as phosphite of potash. Its crystals are irregular four- 
sided prisms or elongated rhomboids. Sometim.es it 
assumes the form of square plates, or of plumose crys- 
tals. Its taste is cooling and agreeable. It is soluble 
in two parts of cold water, and scarcely more soluble in 
boiling water. When exposed to the air it effloresces. 
Before the hlow-pipe it emits a beautiful yellow flame^ 
and melts into a globule, which becomes opaque on 
cooling. 

It is composed of....»«...16'3 acid 

23*7 soda 
60*0 water 

lOO-O 



* J 



f73(J 

/?*!^"- Sp.3. Phospbiit of Ammcma. 

Tbis salt may be prepared bj tl)e same pr occ w w n 
the two last described phosphites. It cfystallizestOM. 
times in long transparent needles, and sometiain is 
foiir*sided prisms terminated bj foitr-sided pyramids 
It has a very sharp saline taste. It is soluble is two 
parts of water at the temperature of (10?, and still noit 
soluble in boiling water. When exposed to the aif, it 
attracts moisture, and becoraies sKgbtly dellqorscem. 
When distilled in a retort the ammonia is disengaged 
partly liquid and partly in the state of gas, holding pkiA. 
pboros in solution, which becomes lamtnoos wkcn 
mixed with oxygen gas. Before the blow-pipe on chv* 
coal, it boils and loses its water of crystallizitioo ; it 
becomes surrounded with a phospbocescent light, aid 
bobbles of phosphureted hydrogen gas are emitted, whidi 
bum in the air with a li^ly flame, and form a fine os. 
ronet of phosphoric acid rapour. This gas is emitted 
also when the salt is heated in a small glass bnlb^ tbc 
tube belonging to which is plunged uiMier mercury. 

This salt is composed o( 26 acid 

51 ammonia 
29 water 

100 

Sp. 3. Phosphite of Ammonia ^and^ Ala (^m si a. 

This salt may be formed by mixing together the 
uqueous solutions of its two component parts. It is 
sparingly soluble in water, and may be obtained in crp. 
tals ; but its properties have not breu txamip.td with 
precision. 



rHOSFHTTES. CS7 

■ 

Sfn 5. PbospUtt of Alumina. - CfayL IIL 

Tfiis salt mnj be prepared bj saturaciog pbospiioroat 
«cid v;itti aluminay and then evaporating tiie aolulioa 
to.a pf^op^.consistence. It does not crystallize, but 
for^ns a glutinous mass, which dries gradually^ and does 
ffiqt afterwards attract jnoisture from the air. Its taste. 
is astniigpnl« U W vtry soluble in water* When heat* 
ed^ it froths and gives out phosphorus, but it does not 
fcadily oielt into a globule of glass. 






Sp. 6* Phosfbiu tf Magnesia. ►aire*. 

This salt is best fdoxied by mixing together aqaeous 
solutions of phosphite of potash . or so|^ and tulpbaie 
of magnesia ; the phosphite of magnesia gradually pc«* 
ctpitales io beautifu} ^h\tt flakes* It has no sensible 
iastc. It is soluble in 400 parts of water at t)ie tempe* 
ratttrecf .90^, aril scarcely more soluble in boiling wa- 
ter* W)ien its solution is eraporated slowly, a transpa- 
rent ^licle forms on. its surface, lakes are deposited, 
and towards the end of the process small tetrahedral 
crystals are precipiuted. When exposed to the air, it 
elBoresoes. When heated, it phosphoresces and melts 
into a glass which becomes opaque on cooling* 

It is composed of* 44 acid 

5to magneda 
' 36 water 



100 

Sp. ^^ Phosphite of Lime* 

This salt may be formed by dissolving litne in phos- 
phorous acid. When the saturation is complete, the salt 




■ALTS. 

pKcipitatcs in ihe state of a white powder. It ii tuit. 
leaa uid insoluble in water ; bill ii diuolTei in an ct. 
ceis of acid, and forms a laperphoiphite. Thtt li^ 
»U may be obtained io priMnatic crysiaU bj cnpo. 
raiing the solution. This nit is not alleccd b^expe- 
sure to tlie air. When heated it photphorcKct tal 
emits a little pbosphonis. In a violent heat itoitln 
into a transparent globule. 
It is composed of 34 add 

51 hmc 

13 water 



100 



1 

nbfMTiliBnMi- ' 



5/. 8. Pbojfbitt of BaryUt. 
I'mi salt majr be formed by pouring pboipbK 
acid into baryies water, or this last water into a wlu' 
tton of phosphite of soda. In ciilicr case pliosphiteof 
barjies prrdpitam in the foim of a white powder. Il 
is tasteless, and but rerj spatingljr soluble io watet, 
unless there be an excess of acid. It is not altered bj; 
exposure to the air. Before the blow. pipe il mtltj, 
anj is surrounded with a light so brilliant that the eye 
can scatcelj bear it. The globule which it forms h 
oomes opaque as it cools. 
It u compo&ed of 41'1 acid 

51'3 barytes 
TO water 

100-0 
Hitherto none of these salts have been applied t* « 
useful purpose. 




OAXA0NATE9. 



Chjp. in. 



Gewus VI. Cahbokates. 

TTiougU several of [he carbonates were in the hands 
»f chemists, and employed by them in the greater num- 
r of ihcir experiments, their nature and composition 
;re entirely ■uiiknoii'n till Dr Black discovered it in 
175fi. Since that time they haa-e been examined with 
P'cat attention by almost every chemist of eminence ; 
I that at present no family of salts is more accurately 
Wndei'stood. The Grst treatiseao the subject was pub- 
lisbed-by Bergman in m*". 

They may be distinguisbed b^ the following proper- 
tic*: 

1. When sulpliuric acid' is poured upon them, they OiarKtair 
ilFcrvesce vJoleoily, emiliing tarbonic acid gas. 

2. When healed strongly, the carbonic acid it drrien 
•«S, and the hattt remains in a state of purity. Some 
carbonales require 2 very violent heat to be thus de- 
«oinposcdi but the operation is facilitated by mixing 
them with chaccual, wlikh decomposes the carbonic 
acid altogether. 

3. The alkaline carbonate* t'lnge vegetable blues 
peen, and have an alkaline taste. 

. The alkaline carbonates are soluble in water ; the 
carbonates with basc4 of the alkaline earths are insolu- 
ble, birt dissolve when an excess of acid is added. 

Many of these salts exist native; but (hey may be 
all formed ariiGcially by dissolving or diffusing the base 
', and making carbonic acid gas pass into the 
Iii]uid till it be saturated. At prcscni i l species are 



known, Kvcral of nhicfa i 
an excess of acid. 



I Soups L> 
Carso- 



Sf. 



Cari 



Tms nit bis been long 
fine Its coinposiliwi Wu 
characterized bj a great v 
the manaer of preparing i 
tartar, vtgttahit alkaS, '• 
described with precision V 
krc two varieties of it ; th 
tuning an exceu of alkali 

Varictj l . CarhoHtUi. 
ntiDg potash frith carboni 
exposing a aolutioa of poti 
CBrbooic acid gas, or bj ci 
■ solution of potash till h 
The potash of comtDcrce i 
pure potash : Bjr distillin 
ammonia, it may be also 
potash f . When potash is 
it always lets fall a ijuan 
has propoied this satdratic 
fying potash from the eart 

It crystallizes, accordinj 
lar prisms ; the apexes of 
inverted triangles, converg 
According to Pelletier the 



priBms, with dihedral summits. The complete crystal Char - 1 
has eight faces, two hexagon's, tivo reciangles, and four 
itlombs*. It has an alkaliae, but not a caustic taste, 
and still gives a green colour lo vegetable blues. Its 
specific gravity is 2*0I2-|-. It is soluble at the com- 
tnon temperature in about four times its weight of wa- 
ter!. Boiling waterdissolvesjlhs of its weight^. Al- 
cohol, even when hot, does not dissolve above tiW^'> 
p«tt of it. Pellelier has observed , that when the crys- 
tallized salt is dissolved in boiling water, bubbles of 
carbonic acid gas are emitted. It is not altered by ez- 
posnre to the air. Heat deprives it of its water and 
part of its acid, but does not decompose it completely. 

The constituents of this salt, according lo the most 
accurate analyses hitherto made, are as follows : 





II 


n 




H 


Acid 


20 

48 


. 




43 
41 


TJ-3 


40 


B.K 


W.ttT 


32 




n 


IG 


Told 


100 


100 


100 


100 



The coincidence between the experiments of KIrwan 
■nd Fclletier is very great, and induces us to coofidc 



« A—. Ji Cbim. IT. 19 
\ Bcigmin, i. 13. 
^ Richter, Statijm Ct: 
•• Kirwut, Nichol»on"> ^. 



f HiMcafnti, Alt. ii Chim. oriit u. 

4 Pellelier. |i Bcrgnutt, 0/.j<. i. 14. 



<t 0. much nioie Lit their results tlian t 



e of the oiUr ^. 



V»rieijr 2, Smbeari^maU, The potash of conmoti 
always occurs in this uiie i but its parity n dampi 
hy the mixtarc of foreign &ubsiances. Puce nibcuw. 
naie of potaih mav be procured hy beating ncuinloi. 
bonait, prcpire«l by the process above described, ton^ 
ness, in a silver or platinnin vessel. A portion <j||i 
carbonic acid is driveo olT. Tlie subcarboiutt t^ 
fbrtncd has » stronger alkaline taste, andaciswilba 
energy on animal and vegetable substance* i 
caTbonaie. When exposed to ibc air itsooodeliqac 
and a.«suiucs ttic con si si en cir of ao oil. It does & 
sorb carbonic acid sensibly from the BtmospLeic ; i: 
excess of alkali cannot be removed by treating the b 
with alcohol. Dr WoiUsion has shown thai t 
contains exactly ene half of ihc a^id wbicta i 
carbonate of potash *. 

The poiaih of coinmerce is alMrays io the stale oTi 
. sitbsalli but it contains likewise several forri|n idIk 
stances which render itie proportion of alkali vanahlt. 
Mr Kirwan has pointed out a very ingeojous mtiliod of 
detecting the cjuaniiljr of alkali in any specimm, byAt 
properly whidi it hat of precipitating alnmina hm 
alata ; aod Vauquelin has published a still simpler tnt. 
Ihod, namely, the quantity of nitrtc acid of a gtm 
density Deces!>ary to saturate a given weight of tJitn 
From hisexperiments, wc learn that the following lc 
of tbis salt known in commerce contain the folloi 
inp'edienis f . 



t Am*, a Ctim. il. : 




WidlBB. 

> ^imM 

•etufiP 
here; the 
S itw all 
I tUtiB 

■ ^ 

itaie of I 

vanahlt. 
DC ihod of 
■n, by At 
ina hn 
pier tnt. 
a gim 

tJitida 

'J 



ARBOMATES 










, 


1 


■3 


"5 


50 


■II 
|| 

254 
IIP 
308 
190 
304 


1 






• Potash of Riifsia 


772 


es 


5 


1152 
1152 




754 

603 


154 

80 
165 

152 


20 
4 
44 
14 


2 
G 
24 

-19 


American I'eaTl-aih 
Potash of Ttevc, 


1152 

-.152 

U40 


D..,u,. 


Vosgsi 


444 


148 


510 


34 


304 


Sf.2. 


7ar6o 




a. 


-OUO 


f Sod 



This sftlt has bceu also ver^ long known. ItUusual- 
By obtained by burning and lixiviacing uarine plants, 
For by decomposing common sail. In commerce ii ix 
kcalled hiirilla or loda. In that slate, however, it is 
Itiever perfectly pure, containing always a mixture of 
learthy bodies, and usually common sail ; bui it iDa> be 
kpurified by dissolving it in a small portion of w^irtr, 
FfilCraiing the solution, and evaporating it ai a low heat, 
I skimming off the crystals of common salt a^ they form 
Bon its surface *. Of this, like the preceding, there are 

wo varieties; the first neutral, the second containing 

B excess nfi>lkali. 



I * 8m • ileisil ot ibc (lifTcrcnC planu irom tthich tliti iiibitance it pio- 
^^^^^daf die mcthud of procuring than, in ibe Amulrr ii Chimii, 




Varietur 1. Carboaatt. Though this nil octnnn. 

live ID Africa in coniiderabte quantities, il wurwti, 
tinguitlied Irom ihe loda of commcrcic, which tti kL 
carb an at t, possess! n|{ very diBifr^nt propet Iim, 'iF^ - 
1BU2| Kbproih published an account of it in 
volume of his works*, < Il is luund in the | 
Sukcna near Fcczan, and is called trona by '.'i I 

It is cryiialliicd in hard striaieri mas&cs, not ali::d jj 
«XpoBUre 10 the air, and of auch harduess that ibcviih 
of Ctttf, B fort now in ruios, >'c »><! ^ '"tc W 
^boiltofit. 

This carboDate majr be formed artifitrtally b; cqt. 
'vngttie common aubeartinnatc of soda loaoaunniJa 
of carbonic acid ^33. In tliat situation it doeinoidtp 
site cryiluh likcsubcarbonaie of potash, butformiin. 
lid shapeless mdsi, having some rcsrinblaace loUbeJU 
frican carbonate. 

When the carbonnte of lodn is exr>oscd to a ttd ht^ 
it losct its water of crystallizatian, and h'kewise i pn^ 
tton of its acid. Its consiituciiii, as detemuned bf lli 
experiments of Klaprotli, ave as follows : 

Acid 30 

Base 38 

Water -2% 



V.iricty 2. SuhcarhariaU. Whal is usuallja 
carbiinaic of soda is merely this salt. It crysialli^ 
dec;iliedf(;ns, composed of two four.sided pyramidi i 
plied base to base, and having their apexes tniacBtedt.fl 



CASBOHATES. 

i is often obtained also in Urge transpKrent flsl rhom- 

>idal prisms. Its taste is precisely the same with that of 

arbonatt of potash. Its specific gravity is l-a59l'. 

soluhit: ill two parts of coJd water, and in rather 

than its weight of boiling water. So that when 

I'lnolved ill boiling water it crystallizes as the solution 

>ols. When exposed to the air, tt very soon efflo- 

•ces and falls to powder. When belted, it under- 

les the waiery lusion ; indeed the soda of commerce 

imciiDQcs contains so much water of crystallization, 

hu, when once melted, it remains pennaneiiily liquid. 

If the lieatbecoiitinued, the water gradually evaporates, 

id Ihe salt becomes dry. In a red heat it melts into 

transparent liquid. A very violent heat drives off 

part ofitiacid. This salt melts rather more easily 

than carbonate of potash, and for that reason it ia pre- 

I f erred by glass manufaciurers. 

''' Iisconsiituenis, accordin); to the analyses of it hither- 
Ho made, are as follows : 



. 




t 


t 


14-42 


40-14 




Acid 






lu 


23 




Base 


20 


21-39 


59-86 








Water 


64 


62 


64 






Tolal 


100 


100 


100 


100 














„ • HuMofraia, At*, ii dim 
f Bergman, Ofi.ii. i. iS ; ui 
I Cogl.Trjnt. 

) KlaiToth, iii. 6j Engl. Tti 



Faurcioy, Syilrmi di Cfu 



ChiV-UI 1 



But either i1i«K aoalj-scs or that of the caHiMfit 4 
inaccorstv, or ihf salts examiued wcfe impoie. 
Dr WoiU»on ha« thowiit tliat wlieti a |>ur« caih« 
of soda ii cxiJOMd to a red best it i> cooveited itftii I 
snbcaibonate, and loicf exactly one half of iu acid', 

Sfi. 2. CarBwtau of Ammoma- 
This >alt hit bcra alto long known. It tt«fba«k I 
uuoed bjdisiilltng animal subataaces i but ford 
cat pUTjioKs it is belt lo cxirsci il from ta] a 
br meaiii of chalk. Two parts of cbalk and one pM I 
ot ill ammoniac, both as dry as pos&iblr, are mixed a^ J 
gftlicT and put into an earthen reiari. On the applies | 
n of a sufficient beat, carbonate of ammonia sublimM, 
i obtained in the state of a wlute crjtulkuj 
onsB. This salt, like tbe other aJkalinc carb<MLUn,ii<if 
two kinds, the neutrai and tahctir&Miatt. 

Vuitty 1. CariHmaU, Tbis salt otaybcobuitidbj 
exposing llic con.mon subcarbonaie of ammoataiolk 
air, or by cauiiog a current of carbonic acid gaa to {N 
through a solution of it in vnier, Jt crystallizes in 
sided priKOi, usuallj' small, has no smdl, and less a 
than the subcarbonaic. According 10 ibc expcriai 
of Schrader, it is composed of about 
, 56 acid 

10 base 
35 water 



lOOt- 



Variety 2. Suhcarhonate. This sail n» iC 



• FU.7n:.i%0l. 




CARBOt<AT£». 

rained iu crystals, but they are so small anil so iTregular, 
that il is diiHcult to ascertain their form. According to 
Bergman, they may be obtained in octahedrons, having, 
for the most part, their two opposite apexes truncated *. 
The tasie and smell of this salt, though much weaker, 
sire the same tviih those of pure ammonia. Ltke all thi: 
alkaline carbonates, it couverls vegetable blues to green, 
precisely as pure alkalies do. Its specific gravity is 
O-ges t- It is soluble in rather less than twice its weight 
of cold water. Hot water dissolves its own weight of il. 
Boiling w^ter cannot be employed, because at that heat 
the carbonate is volatilized. It is not altered by expo- 
sure to the air. When heated it evaporates very spee- 
dily. 

Mr Davy has shown that the component parts of this * 
salt vary exceedingly, according to the manner of pre- 
paring it. The lower the temperature at which it is 
formed the greater is the proportion of acid and water 
which it contains i and, on the other hand, the higher 
the tcmperaluru the greater is the proportion of alkali. 
Thus caibonate of ammonia, formed at the temperature 
of 300", contained more than 50 ptr etnt. of alkali, 
while carbonatt! formed at 6o°, contained only 20 per 
cent, t- Il> constituents of course must be variously 
stated by chemists, according to tbe state in which ihej^ 
fonnd it. The following table exhibits some of these 
results. 



• Bergman, i, 



I H<iKBfrali, Aim.iUCt'm- a 



64§ 

Bookir. 
DhrisimftL 



tALtSi 



tl. IlltOLU« 

■lkCar* 

•ONATIt. 



Prepara- 
tion. 





t 


f 


II 


K j 


Acid 


45 


48 to 50 


50 to 52 


68-5 


Base 


43 






31-5 


Water 


12 

• 

100 








Total 






100 



Sp. 4. Carhonate of jimmonia'^nd'' Magnesia. 

Tuis salt has been formed bj Fourcroy bjr mismi 
together aqueous solutions of its two component paitSi 
but it properties have not been examined. 



Sf.5* Carbonate of Magmesia* 

This salt has been long knou^n. Its compositioB 
was first discovered by Dr Black ; afterwards its pro- 
perties were investigated bj Bergman and Botiniy and 
more lately by Fourcroy *. There are two varieties of 
it : the first neutral ; the second containing an ex- 
ce^s of base. 

Variety i. Subcarbonate. This salt is usually pre- 
pared by mixing together the solutions of sulphate of 
magnesia and carbonate of potash, and applying heat. 
The carbonate of magnesia precipitates in the state of a 
white powder. Such is the state in which it occurs Iq 



t Bcr^'min, i. 21. 

( Schrailrr, Gchlcn's Jour. n. 583. When in a toliJ matt. 

;• Ditto. When crvntalJifcd. 

^ Kirwaii, Nicholson** ^ irto Jcvr. ilL ai5. 

♦ -lin.de dim. ii. 2; 8. 



CARBONATES. 649 

eommerce 5 but Foorcroy has shown that in that state Chtp . in. 
if does not contain a maximnm of acid. It is therefore 
onlj a subcarbonate ; but it maj e saturated with acid 
bj difFusing it in water, and making carbonic acid gas 
pass through it till it be saturated and dissolved. 

Variety 2. Carbonate. . The carbonate, thus formed, 
yields by evaporation crystals which are transparent 
hexagonal prisms, terminated by a hexagonal plane : 
these are partly in groups and partly solitary : their 
length is about six lines, their breadth two *. But it 
may be obtained in more regular crystals, by mixing 
together 125 parts of sulphate of magnesia and 130 
parts of carbonate of soda, both dissolved in water, fil- 
tering the solution, and then setting it aside. In two or 
three days the carbonate of magnesia crystallizes. 

This salt has little taste. Its specific gravity, when Propettki. 
in powder, is only 0'2Q41 according to Hassenfratz f • 
It is soluble, when crystallized, in 48 parts of cold wa- 
ter ; but when in powder, it requires at least ten times 
%s much ; and what is very remarkable, it is more so- 
luble in cold than in hot water impregnated with car- 
bonic acid X* When exposed to the air, it effloresces, 
and falls into powder $• When heated, it decrepitates, 
falls into powder, and is decomposed. 

The constituents of this salt are as follows : 



* Butisi, tur U Ma^nu'u, f Ann. de Cbim, xxviii. Zl. 

t Butinf. ) Folircroy, Anm. dt CUm. iL 098. 






t 


t ' 


Acid j 50 JO 


36 


Baje 


25 43 


43 


Water 


55* 25 


21 


Total 


100 lOO 


100 



Bot the carbooate examiocd bj the two last chtabb 
does not teem to have been £uUj saturafed with tod* 
The maf^nesia of comoiercey according to Kirwan, ii 
composed of •••••••••• 34 acid 

45 magnesia^ 

21 water 

iOO|. 



I^opertietk 



Sf. 6» Carbonate of Jime^ 

This substance, under the names of marble, chalL 
limestoncy &c. exists in great abundance in natare, 
.variously mixed with other bodies. It is perhaps the 
most important and most generally used of all the salts, 
unless we except muriate of soda. Its properties of 
course have been very completely investigated. 

It isoften found crystallized and perfectly transparent. 
The primitive form of its crystals is the rhomboidal 
prism with angles of 101|«> and 78t°. Its integrant 
particles have the same form. But, besides the primi- 
tive, no less than G16varietiesof its crystalshave been dis- 



• Fourcroy and Kirwan. 
{ IC'u'Solioti*s Jour, iii. 215- 



f Berztnin. 



t Bttdei. 



CARBONATES. 



654 



covered and described by roinertlogists. It lias scnrcely Chap^ ni. 
uny taste. Its specific gravity is about 2*7. It is inso- 
luble in pure water ; but ^\'ater saturated with carbonic 
mcid dissolves -rrv?^ P^^ of it; from this solution it 
gradually precipitates, as the acid leaves it, in the form 
of a white powder ^. It suffers little or no alteration by 
being exposed to. the air. When exposed to heat, it de- 
crepitates and loses its water, and afterwards its acid se- 
parates as the heat is increased : But to separate the acid 
completely, a pretty strong heat is required. 
Its component parts are as follows : 

Coin|K)li- 
tififi. 





t 
34 
55 
11 
100 


t 

45 

55 

100 


50 


Acid 


Base 


50 


Water 




Total 


KiO 



Some very interesting experiments on the fusibility of 
this salt were made by Sir James Hall. The result was^ 
that when the carbonic acid is prevented from making 
its escape by strong compression, the salt melts at a 
red heat, and assumes an appearance which has some 
resembldnce to granular limeitone* A portion of the 
carbonic acid is usually dissipated. This portion is 



• Bcrginmii, 1. 16. | Bergman, O/v/c. i. aj. 

I Kirwsm, NichoIiOD*8 Joymal^ iil 215. 

{ In this analysis the water is confounded with the acid. This wate 
seems in crystallized pure carbonate to amount to three or four /rr ctmt ^ 

* 

but I have not b^en able to ascertain its proportion, became the whole 
el* it separates in combinacion with the carbaoic acid. 



• Book ir. sometimes vcrv small, and very often it docs ocia. 

«.— Y^-. ceed 4 or 5 ptr cent. Buchoiz has latelj ver&i 
thrse experiments in a very unexpected manner. Be 
put 4t pounds of waslied chalk (carbonate of lime wi^ 
only 0-005 of. foreign matter) into a crucible, prtSKi 
it stronglj down, and exposed it covered to a strong 
heat in a furnace. The chalk, except a smaU ponioQ 
on the surface, was converted into a foliated, hard, 
yellowish mass, having considerable transpareacj, 
which obviously had undergone a commenoeiDent ol 
fusion. It was obviously in a similar state with Six 
James Hall's carbonate of lime, and contained 42 /tr 
cent, of carbonic acid *. Here the same effect was pro* 
duced without compression. It must have depended 
no doubt upon the degree of heat to which the crucible 
was exposed. 

Sp. 7. Carbonate of Barytes. 

This salt seems first to have been examined by Berg* 
man. Withering first found it native in 17S3. Hence 
it has received the name of Witbcrite. Since that time 
it has been examined by Kirwan, Klaproth, Hope, Pel. 
Ictier, Fourcroy, and Vauquclin, and its properties de. 
scribed with great precision. It may be prepared arri- 
ficially by exposing barytes water to the open air, or 
by passing carbonic acid gas into it. In either case 
the carbonate precipitates in the state of a white pov?'. 
dcr. 
Properties, It is found native crystallized. Its crystals have 
been observed to assume four different forms ^ double 



• Gchlcii*! JbkT* ad Series, i. 271. 



CARBONATES. 



65^ 



^ six-sided and double four-sided pyramids, six-sided co« Chap.nL 
:v lumns terminated bj a pyramid with the same number 
[^ of £ftcesy and small radiated crystals half an inch in 
. . length and very thin, appearing to be hexagonal prisms 
^ coooded towards the point. It has no sensible taste ; 
. yet it is poisonous. Its specific gravity, when native^ 
is 4*331 ; when prepared artificially, it scarcely exceeds 
3*163. 

Gold water dissolves tjVt P^^» ^°^ boiling watei^ 
•rrvT P^^^ ^^ ^'^^ ^^^* Water saturated with carbonic 
acid dissolves ^4^ P^^ IT* ^^ ^^ ^^^ altered by exposure* 
to the air. It is decomposed by the application of a* 
very violent heat ||, either in a black lead crucible, or 
vrhen formed mto a paste with charcoal powder. 

The constituents of this salt, according to the experi- 
ments of different chemists, are as follows : 



Compcs!- 

tion. 





-IT 


f 
20 


•« 


t 
22 


J 


Acid 


7 


21-67 


22 
78 


Base 


65 

28 


80 


78'33 


62 


Water 




16 


Total 


100 




100*00 


100 


100 



Sp. ^» Carbonate of Strontian. 

Tins salt was first pointed out as distinct from the History, 
last species by Crawford in 1790 ; but we are indebted 



\ Fourcroy, Ann. de Cbim. iv. 64. 

* Bergtntn, Oputc. i. 31. f Withering. 

• • Aiken, Nichobon's /wr. xHu 303. 

§ Kirwan, NichokoD*! ^otf Jwr. iii. %%$% 



fl Dr Hope. 
\ Pclleticr. 



ofboijj 



SALTS. 

fo[ the first accurate account of it to Dr Hojk. Ki 1 
' cxptrtmcnt* wrrc arierwartls cDofirmed hy KJipMi, 
Pelleticr, Fotircrojr, and Vaiiquclin. It has beta tgnl ' 
native &t Stronti-Jii in Ar^yluhire uid at LndbiSi ■ 
Scottafid. It is 111U1II7 ia striated xcmitrint 
ai&»>c§, which have a greenish linge. 

li ha* no iBMe. It requires 1530 partfof b 
water to flissolvL- it *. Its specific gravity is about ^ffi. 
It is not alicrcd by exposure to the air. Wben Ksm^. 
\y heated in a crucible, it loses part of its tai; ^ 
this decompositton is facilitated by making it lEto 1 
paste with chiircoal powder. Accerdrng to Samnt, 
it melts inio a transparent glau at the tenperxiiinrf 
526* Wcdgcwood t- When ihrovrn in pcnrdtr ti 
burning coals, it produces red sparks. 

Its component parts are as follotvft : 





I 


^ 


« i 


Acid 


30-2 


30 


30-0 


Base 


01-2 


02 


1)9' 5 


Water 


8-t) 
100-(1 


8 


0-5 


Total 


100 


IOH-0 



Sfi. 9. Caibonait of Altt/nina. 

The greater numbtT of chemists have agreed in t 
laitting the existence of this i)\\. Bergman couM j 



• Hope. 7*™.. Kdi*. i». 
I Hope, Tm,. Eil.. i(. 
\ KlJprnlh, Bcilrj'!,!. 1 



i r<llctier, .^a. A eum. n 
uiil KUwaD, Nicbolsuci'* /wr.i&l 



CARBONATES. Ci5§ 

fbrm it artificially; but he allows its existence, because ^W- *W. 
Mr hen alum is nuzed with an alkaline carbonate, part of 
the alumina remains in solution till the carbonic acid 
be driven oflf *. Saussure has shown lately, that water 
Saturated with carbonic acid, is capable of dissolving 
aluiuina ; but this coAibination is destroyed bj simple 
exposure to the air« Carbonate of alumina, then, can* 
not exist in a 'dry state. What had been considered for* 
merly as a dry carbonate is a triple compound of alumi- 
na, carbonic acid, and the alkali employed in precipita* 
ting the alumina f . 

5^, 10. £arbonate of Yttria» 

TiHS salt may be formed by precifiitatinf yttria frofm 
its solution in acids by means of an alkaline carbonate. 
It i« a white, tasteless, insoluble powder, composed of 

18 acid 

55 yttria 

J27 walcr 



100 J 



.S^* II. Carbonate of Ghcima. 

This salt has been examined only by Vauquelin. It' 
«ay be prepared by precipitating glucina from its so- 
lution in acids by an alkaline carbonate, and washing 
the precipiute sufficiently with pure water. It is in the 
state of a white soft powder, which has a greasy feel. 
It has no taste, and is exceedingly light. It is insolu- 



% Klaproth*s Beitrage^ liL 67. 



€50 &AZ.TS* 

Book n. ble in water, not altered by exposure to the tir, eadr 

< ■y t decomposed^ and iti acid driven off bj the applictdtttf 

heat. 

i 

I Sf. 12. Carbonate ^ 

\ This salt was formed bj Vau^uelin bj predpititb 

zirconia from iu solution in acids bj alkalinecarbooUci 
It is a tasteles white powder, composed of 

44*5 acid and ^prater 

55*5 urconta 



100-0 



When heated the carbonic acid is driven off. This 
salt is soluble in the three alkaline carbonates, and kobs 
to form with them triple salts. 



Such arc the properties of the carbonates. The bt- 

lowing Table gives a view of their constituents according 
to the most accurate analysis : 



F 



CARBOHATCS. 





SWubiLi^ 


Co-uiimnU. 






W.Wr 


100 


33-9 


W..*,. 




A.nmonia 


50 


44-6 




Magnesia 


2 


ion 


50 


50 




Poiash..., 


25 


100 
100 
100 


S5-8 


37 








Soda 

Lime 


50 



fir4 

122 










Sironiian i o 

Tuda....| 


loo 

100 


231 






305-5 


150 




Baryies... i) 


100 


354-5 







All the carbonates are insoluble in alcohol ; but the 
illkaiine subcarbonates are patliall^ soluble in that li- 
quid: 



From the peculiar nature of the acid whirh exists In 
these sjIis, (heaikaline carbonates were long confounded 
with tiieir bases. The alkaline character of iheje bases 
is by no means destroyed by the presence of the acid, and 
it is easily removed either by means of heat, or by the 
ftction of aOme other base. Hence the alkaline carbo- 
nates are applied lu all the uses for whicli the pure al- 
kalies are adapted. These are too numerous and well 
known to rcijuire a particular detail. The use of cir- 
^naie of lime as a manure, a paint, and a mci'icine, 
k Hader t^L; names of lime, Whittug, ciab'ii eyes, Sw. is 

pu. li. u tt 



j^^ C(,u«llr well lamwu. NanesTl 

^^ V • have cocM into uw, except the i , 

^ >■■, which b occwfooallj- rmplujij v s 



Gi;itvs VII. Sm.rm*3m. 

Solprhxk acpd i« capable of «^|^ 
the BlkalietMdnrUiii except silica. TWa 

nlmost all capahlc of atmtning a « 
Their i«tp. wh«n ihey have any, ia^ 
They may be iltsdnguishni A^Mtietbcr 
the following prapcrtifa. 
•aweef* I. Tl.eyare mmluble in alcohol. , 

dijiolved ia «,»,«,, alcohol prccipitatea tW_ 
liquid, aDd it precipiiafe* them crysialfiucl 
2. Heat does not readily decompotc A^ 
tins there art numeroas cxcepticma, Haa J 
■ulphaiei arc deeom[«»ed by a red beat caM 
or totally ; pan of the ,cid escape, oftaltrmi. . 
a, h« been .ho«-nby tt.c cx,>eriment.of Gaj-I^ 
i» decomposed into sulphnrotis acid and oirpa , 
Ip.hcalkUi«e supersulphatea .he e«e., of ;d*il 
panted .n the »me way, partly onaJtefed. . 
the stale of siilphorom acid and oxrgen gaj, 

3. When heated torednew alon/wiih cha 
are con\-erted into sulphurela. 

4. When barj-iic waier, or a tohiiion of u 
(aining barytes, is dropt into a oolutjoa of t 
sulphates in waler, n copion. white prccipita 
(liately fails, which it insoluble ia acetic a 



*ji;'--/-^r/«tf,i.„^ 




w 



^ 



Sfi. 1. Sulphate o/Potaib. 



I^^Jbe genus of sulphates contains more species than Clup. i 
1^ other, owing to the great tei^ency which the add 
to farm triple salts. Many of the sulphates are ca- 

, sk of combining with an excess of acid, and of 

^niag mferialtr. 

I 

ngpr diissalt there are two varieties. The first )s 
^eutral, the second contains an excess of acid. 

Variety 1. Sulphate. This salt may be formed by 
'pturating diluted potash with sulphuric acid, and then 
Waporating the solution gently till crystals appear. It 
k»m3 to have been known at a very early period by 
piemists, and a great variety of names were given to it, 
Iccording to the manner of forming it, or the fancy of 
Be operator. Some of these names were, sfecificum Nimti. 
Isrifffn^, nitrumj\\uni, arcanum daplicatum,panacta bol- 
tatica, sat dt duobui, sat pctychrest gtaseri, Sn-C. but it 
ins commonly known by the name of vitriotatej tar- 
br till the Freuch chemists called it sulpl/ate o/polatb 
kvben they formed their new nomenclature in 1137 *■ 

When thesoluiionofsulphateof potash is sufficiently Propettict. 
Bilnted, it affords by evaporation bexahedral pyramids, 
or short ht^xangular prisms, terminated by one or more 
bexangular pyramids. But these crystals vary much in 
tbeir figure, according to the care with which they are 
pre pared. 

It has a very disagreeable bitter taste. Its specitic 



* Bergmin called it aliali ti^tl-ttUi vilihhtvm, and Mdttciu vi'lriW 
0U2 



h. 




^n^ty according to WaUeritu * U a-2M ; Mcanb|i 
H«*enfr»ix, 2-4013 f : according to Wuxo, riH] 
At the irmpcratuTc of 60° it di«solTn in lo ami 
Weight of water ; in a boiltog beat it i% wlnUcab 
timn In weight {. When it it boiled in min, A 
tiqaid diitoWci 0-242 partly or ncMtly {th of at Wf 
of it II. 

It luf&n no alteration when esposed to-tbe lir. n 
placed upon butaing coal», it dcrrepttatea,baiB&i 
other alieraliaa. In a red heat it mcll^ nd 
ftr eent. o( it) weight. It ia sometimes 
difki as Mr Giofaen hat observed 

Ita component pina, according to the saaljKttiA 
to puBtishcd, are zi follows : 

IT 



t mclt^ '"'''9 
dT T 



Acid 



Water 
Total 



36-4 



++ 




38 5 



40 



TT 



7! 



M- 



5S- 1 5«-a 

77 



Variet;- 3. Superntlpbatt. This sak majr be pttya 
h/ beaiiog t<^etfaer a mixture of three parM of aol^ 



•• TbcaaW toA Roud, .rfM.ib Ciw. Bi. ^ 

BB 

n Tlu w the rCMik af mj uulfu. lOO Orunt «f Aucd w 

p«( ii8 al' nlfhiM of birjle 

itill indkMe 411. 
B JSiirwu, NidubM'i Jicr. iS. ■■/. f| Wa 



1 



r 



fftJLPHATxs. est 

V^ potash and one part of sulphuric acid. It was first Ch^p . IIL 
l^4>itinguished from the first varieiy by Rouelle senior, 
h It usuali)' crystallines id long slender needles, but it ftopucitb 
^Biay be obtained in six-sided prisms. lis taste is acrid, 
i^Uid it reddens vegetable blues. It is sohible in live 
^|»rti of water at the lemperaime of Gu" *. It is scarce. 
Jy altered by exposure to the air. When heated it 
l^clis readily and assumes the appearance of oil, but it 
jilbecomes as while as ever when allowed to cool. A 
}vtTy violent and^ong continued heat dissipates the ex- 
kicess af acid, and converts it into sulphate. Dr Wol- 
fluton has shown, that this salt contains just twice as 
ijnuch acid as the tuipbatt \. 

t, But besides these two varieties, there are several 
ttthers not yet particularly described. At least 1 have 
Lfoimd the proporiioo of acid to vary considerably in di£. 
^rent states of the salt, 

Sp. 2. Sulphate of Soda. 

This salt was first discovered by Glauber, a Germart 
.chemist, and for that reason was long known by the 
^ame of Clauhtr't salt. He* himself called it tal mlra- 
ait. It may be prepared by saturating &oda with sul- 
j)hunc acid ; but it is more usually obtained by d» 
■composing common salt in order lo procure muriatic 
acid. Like the sulphate of potash, it is capable of ex- 
isting in two states. In the one it is neutral, in the other 
at has an excess of acid. 

Variety 1. Sulphate. This is the state in-which fli* 



■ Uuk, CrtlTi Ammak, 1796, i. 16. 

4-On nipcncid ui4 tubicid siti. Flat, Tr-ni, iSoL 



I 





SALTS. 

salt 1UUBII7 occars la commeree, bdng prepmii 
fjceal qiiBiitict by the manufactured of sal 
lis crysi-tls arc transparent, and when fonaal hy im 
cvapoiatiun, arcaixsldcd prisms, terminated bj£l 
sutnmiis. The sides of the prisms are ittaall; 
nelled, and the ciysiah arc almost nln-a^s eut«£if|f 
ineniilar. Its sprcific gravity, according to WiDm^ 
is Z-24C * ; Dr WaisoD, by a oivihod not micrpuUcif 
much precision ^on account of the ready solaiuIi:ji£ 
this salt), found it l'3S0 f- 

Its tsMe at lirst has some resemblance to thatof otft 
mon sail, but soon becomes very ditagreeabty tnotr. 
It is soiubte in 2'Sn limes its weight of water u fit 
temperature of 60", and in 0"8 of boiling waierl. Vha 
heated to rednesi) so as (d drive off* its water of ctjuA 
Jization, and then pounded in ■ mortar, it ditsolits ii 
3-3 it* weij-ht of water at the tempcraiUTe of lM*t 
When exposed to the air, it loses great part of iuat. 
ter, and falls into a while powder |(, but it is riot odic- 
wise altered. It loses about 56 frfr eent, of its irci^lnf , 

When exposed to heat, it first undergoes xhwSiir) 
fusion"', then its water is evaporated, itisiedundto 
a white pnwder, and in a red heat it melli. Mi 
^irwan has observed, that pan of the acid, •> 
the water, is driven off by the application of a 
heat ft. 



• WiQerini* Ctrmit fijiua, iii. 

n SalneincM which Tall lo powder in thi* 



• • Wlicn nibmncMi 



f WeiJicl. p. 



^* Its constituents, according to the most accurate ana- Chifk^. 
hitherto made, are as follows : _ ' 





• 


+ t 


i 


Acid 
Base 


2:1 -52 


27 55-7 


56 
44 


18-48 


15 


44-3 


Waler 


58-00 


56 




Toial 


ino 


100 


100 


100 



These analyses differ but little from each other; that of 
Kirwan is probably the nearest precision. 

Variety 2. Superiulpbate. Wfaen the sulphate of 
9oda is dissolved in sulphuric acid, if thetolulion be set 
«side, it deposites spontaneously large rhomboidal crys. 
lals which contain an excess of acid. They effloresce 
to the air, and lose their excess of acid when moderate- 
ly heated. At the temperature of 66° they dissolve in 
twice iheir weight of water [j. 

Sp. 3. Sulphatt of jitmnonia. 
This salt was discovered by Glauber, and called by 
him stcrtt lal ammoniac. It was also called ■vitriolattd 
ammoniac. It may be prepared by saturating ammonia 
with sulphuric acid, or by decomposing sal ammoniac 
by means of sulphuric acid. 



* Kirwan, Nicholson'i ^dri>yui', iii. iij. 

t BcigmaD, i. 133. 1 WeBlel't Vtra^mJlutaft, p. j«, 

) Kirwan. JJU. Ths two firM amlyia were made upoD th; cryKali 
tf the nit, the two i»i uputi the ult Hj>po*cd Ircc Inun vu^^ 
g Link, Crell') AM-th, 179$. i. 17. 




Tis crystals are gcnertiily small ■ix-aidedpritmi, 
planes are unequal, teritiinattd hy lix-stded pyi 
I h«* a (harp biller Ust*. It i» soluble in t« 
own weight of water at ihe (etnprraiure of 60", 
weight of boiling water. Water of the 
mure of I4-*^ dissolves 0-78 of its weight of ^ 
When exposed to ihe air, it slowly Uiracts meu 

When healed, it first dccrcpi<aies, then ro«ltl, 
close vessels iiiblimcs, but with some loss of il 
li f. In that state it might be called lUprriM^ 
ammonia, as it contains nn excess of acid, baa 
lasie, and reddens vegerable bluei. Whra hcue 
\j to rednesi, ibe greatest part of il is dccoil 
tulphurous acid oomea over ftnd some am 
a great quantity of aiolic gas is diaengaged, sm 
piobability water is formed J. 

Its coastiiuenCs have been dctemttned asli 




■OLFUATES. fas 

These analyses differ very much from each other in Chap. Tif. 
Ihe proportion of ammonia. Tbe statement of Kiiwaa 
appears to be ifac most correct. ' 

Sp. 4. Sulphatt of Magneiia. 
Tins salt is held in solution in the springs at Epsom 
in England, and was procured from them hj evaporation I 

more than a century ago. Hence the term Efiom tak, ' 

bj which it was long distinguished. Some account of 
it was given by Grew in 1615 j and in 1123, Mr Brown 
published a description of the piocess employed in ex- 
tracting il from ihe springs, and in purifying it *. In 
Italy it is manufactured from shislose mineratt, con- J 

taining sulphur and magnesia. By roasting these mi- I 

nerals, and then moistening them and exposing them to 1 

Ihe air, the salt effloresces on their surface. By solu- 
tion in water, with the addition of a little lime to preci.. 
pi tate any metallic substance that may be in solution, 
and repeated crystallizations, the salt is obtained in a 
Itatc of purity +. 

It exists in considerable quantity in tea-water ; and 
the uncrystalliied residuum in the salt pans, after all 
the common salt has crysialliiedj consists partly of this 
salt dissolved in water. This residuum is usually cal- 
led hittern, and sometimes in Scotland spirit of i alt. 

Sulphate of magnesia crystallizes in quadrangular properties, 
prisms, whose planes are equal, surmounted by qua- 
drangular pyramids, or by dihedral summits. The 
primitive form of its crystals is, according to Hauy, a 
ibur-sided prism, whose bases are squares. The form of 

•fUf. T»». ui>ij«8. 

f .ilM. i!c Oix. ilvui. Eo. G(«alioGcblcii')/»r. iu.J49' 



fc 



I 



i 

it 



"-^<C im 




*ju Tkajul 







MMfMsfett, 




•fdbc 




MM 



Acid .j 20*35 



Bate 



Water 



Toul 



n 



30-04 



]6'S6 



•t 



53*65 52-30 



100 



101 



T~=^ 



tf 



32 3J^ 01-9 , 03-32 



19 19 3S-1 > 30-6S 



40 40 



100 lOO lOO IlOO 



• MsNctifnts, Am.itChkm. %%^u la. f 

I Ihid. p. 377' II Ibid. 

\\ Richwr, 5#tf/fy»# Chfmi^mr^ I. Ij6. 



Ofmtuui^, 



Wcszd, p. 6l 



SULPHATES. 



^^^Hfatse analyses do not difr<.r much from each other ; 
^^nbably a mean of the whole would come pretty near 
L the accurate result. 

I Sp. 5. Sulphate 0/ Potath-and-Ammoitia. 

* This salt, which was first described by Link, may 
1^ be formed by saturating the supersulphate of potash 
I with ammonia. The crystals are brilliant plates, h^ 
W ving B bitter tasle, and ootalteied by exposure to the air, 
Tbcy arc composed of 

fiO sulphate of potash 
40 sulphate gf ammonia 

100* 
sp. 6. Sulphate of Polaih-and-Magnesia. 
Thie salt, as well as the last, was Ersi described by 
Link. He formed it by saturating supersulphaie of 
potash with magnesia. Berthollct formed the same salt 
by mixing together equal solutions of sulphate of pot- 
ash and muriate of magnesia, and evaporating the mix- 
ture. Crystals of sulphate of potash, with a little mu- 
riate of magnesia, are first obtained, and then the triple 
salt in rhomboidal crystals, which are not altered by ex- 
posure to the air. Their solubility is nearly the taoic 
as that of sulphate of potash t- 

The lastc of this salt is bitter. It is composed of 
3 parts sulphate of potash 
* 4 parts sulpba-ie of magneua 

n 



• Linli,CrcU't ^"h/j, I7g6. i. tg. 
\ Link, (Jrcll'i Jma/i, 1796, i. je. 



Sfi. T. Sulfhalt of Soda-and.A'nmimia. 

This salt W2sfir}i described bj L<nlc, wlio foniwdit J 
bjr iaiur3ling»ui>erbulphai«; of soda vriilt imiuonia. Sexfl 
guiii formed ttby mixing logdher tlic soluiioosofakl 
phatc of soda and sul[ihatc of Kln^>onia^ and cvipo 
titig the ni'Xiure. The triple aali is obtained in a 
TliCM crjaials are tegular, and are aoi alirred bj Ufa. 1 
sure to the air. Tlicir laMe it pungent sod bms. 
When hcaicd they dectepitale and swell, aiuDoaiiK 
Gnt di-cngnged, and supcrsulphaie of aramaaiaandiiil. 
phitc (if soda remain. Soda cle«oinpotes it bjr drtTiBi 
off ibe ammonia *. 

According 10 Link, it ii compoaed of 

5 parti lulphate of »oda 
B puts tulpbatc of ammonia 

I4t 

Zp, S. Sttlfthate of Saia'tutd- Magntsia. 

Link obtained thitiali by saturating Mipersolphatc 
of soda with magnesia, and evaporating the toluuoB. 
The nystiilt arc prismatic, large, hare s bitter laat^ind 
cSorcscc in the air. li i> composed of 

5 parts sulphate of sod* 

6 parts lulphate of msgoesM 

in 



*jmr. it Athi. An. lap. let 
I Unk, Ibid. 



t CrcU'* <<«•!(, iJlrfiLj^ 



Sp. 9- Sulpbatt of Magncsia-ani-Jlmtnonia. 

This salt was pointed out by Bergman ; but Four- 
croy was the first chemisl who examined its properties $. 
It inay be prepared by mixing together saturated solu- 
tions of sulphate of ammonia and of magnesia. Cry- 
stals almost immedtaiely precipitate, which consist of 
tbe two salts combined together. Or it may be prepa- 
red by pouring ammonia into a solution of sulphate of 
(nagnesia. Part only of the magnesia is precipitated. 
This is 10 be removed by filtration ; and on evaporating 
the solution, the compound salt is obtained in crystals. 

This salt crystallizes in octahedrons. Its taste is »• 
crid and bitter. Its specific j^ravity ts 1-690 *. It it 
Irss soluble in water than either of its component pirt(< 
When heated it undergoes the watery fusion ; and if 
the heat be increased, it is decomposed. It is not al- 
lered by exposure to the air. 

It is composed, according to the analysis of Four, 
croy, of 

SS sulphate of magnesia 
32 sulphate of anunonia 




Com pad* 



Sp. 10. Sulphatt of Alumna. 
This salt may be formed by dissolving alumina la 
■ulphuric acid, evaporating the solution to dryness, dis- 
solving il again in water, and evaporating it till it cry- 
stallizes. Little attention has hitberto been paid to this 
■all, which was never property distinguished from alum 



• HiMcnrn:*, Ibid, i: 



till two memoirs, nne by Vaiiqn<dra aod 9 
t Cliapfil, en l)ic ratufc of alum, made tbctr »pptc« I 
in the Z.-d Volume of ihe Amtalti d* Cbtmu. 

Il crjrsixllizeii in ihin plates, soft and pliani^ait^i 
pearl; lusire. I» taste isaMringeni. It is vcrjnhilfe I 
in water, Kiid does not cryttallize without jifiab. T 
When hcsied il loies its water of crTStallititina, hj I 
falls to powder. A Strang lieat decompasei il Ofr 1 
pleirly by volatilizing llie acid. It is not alwnl ^ I 
exposure lo llie air. 

Sj>. II. //Aun. 

Of this sail there are no less than fnur vaneties, d ' 
of which are triple salts; two n«utra!j and two in Ai 
State of supcrsalts. These varieties tnajr be distinga^ 
ed hy the followitig names : 

1. Sulphate of »lumin>>and- potash. 

a. Sulphate of al uniina-and-amm on ia. 

3. Super^ulptiuir of alumina-and-potnsh. 

4. SupcTsulphaie of alutnina^aQd-ammonia. 
The two last of these varieties are usually confoi 

ed together under the name of a/imi .- ibe two first b 
been called (t/am snlurated uiith ilt tartht, and ■ 
limes aluminattd alum. It will be proper to o 
the two last varieties first, because they have \ 
longest known, and are the most important. 

Variety l. Tht luptrtulpbatn. The mmfim of|| 
Greeks, and the alumn of the Romans, was a b 
substance, which appears to have been nearljr rehl 
to gretn vitriol or 3u!phatr of iron ,- and which t 
quetitly was very different from whal wc at pro 
denominate tilum. From the researches of Profea 
ficckman, il Appears that wc owe the discovery of li 



l^o the Asiatics ; but at what period, or by what means. Chip. lU. 
it ,i*e discovery was made, 15 altogether unknown. It ' 

CBOntinued to be imported from the cast till the l5lh 
~ eentnrj, when a number of alum works were csiablish- 
^ ed in Italy. In the 16th century it was manufactured 
in Germany and Spain ; and during Queen Elizabeth's 
t «etgn an alum work was established in England by 
J Thomas Chalomer. The alum of commerce is usually 
obtained from native mix[ures of pyrites and clay, or 
Milphunc acid and clay. 

Bergman has published a very complete dissertation 
oa the process usually followed *. The earth from 
ivhich it is procured is usually calied aluminous schittas, 
because it is slaly. Its colour is blackish, because it 
contains some bitumen. In most cases it is necessary 
to burn it before it can be employed ; this is done by 
means of a slow smothered fire. Sometimes long expo- 
sure to the weather is sufficient to produce an efflores- 
cence of alum on the surface. It is then lixiviated, and 
the water concentrated by evaporation, and mixed with 
putrid urine, or muriate of potash ; crystals of alum 
and of sulphate of iron usually farm together. 

The composition of alum has been but lately under- 
stood with accuracy. It has been long known, indeed, 
that one of its ingredients is sulphuric acidf ^ and the 
rxperimenls of Pott and Margraf proved incontestibly 
thai alumina is another ingredient. But sulphuric acid 
Bud alumina are incapable of forming alum. Manufac- 



• 0^«. i.179. 

fSoiTK chemiHi have ihoughc ptop«r U 
tUSedbydlKiUiDiilainiyirif ^tJa-t. 






turers knew that the addition ofa qnantily o(pebm 
I or of atnroonia, or of some &ub«iancc coniaining d 
alkalies, it almost always nrcestarjr ; attd it was p 
that in evtry case in which such wldiliona are u 
sary, the earth from tvhich the alum U ohtaiucd contsn 
already a qiiantiiy of potash. VatioBS cotijecmret win 
made about ibe part wliich potash acts in ibis CKie|l 
Vauquelin * and Chaptal f appear to haw been tl 
chemists that ascertained by decisive experimeti 
alum is a triple salt, composed of sulphtiTtc acid, ij 
na, and pntaih or ammoDia, anited together. 

Alum crystallizes in ccffiilBr octalicdfons, con 
of two four-sided pyramtds applied base to base. 
sides are equilateral triangles. The form of its inie. 
f(rant panicles, according to Hauy, H ihe rr^ubi leiiv 
hedron. Its iHSte is sweetish and very asirtni^t. It 
always reddens vcgeiabic blues. Its specific grariirii 
l-71(J0t' At the temperature of bO° it issolablein 
from 15 to 2u parts of water, and in |ihs of its weiglil 
of boiling water. When exposed to ibe air it c 
mces slightly. When expoicd lo a gentle ha 
dergocs the watery fuiion. A strong heat est 
awell and /oain, and to lose nbuut 44 f*r crat. of 'i| 
weiglit, consisting chiefty cf water of crysialliutionl. 
What rcmnins is called ealeintJ or burnt alutHy and is 
tometiires used a« a corrosive. By a violeot heat, tbe 
greater part of the acid may be driven off. In that case^ 
•■ waa Gtsi observed by Gay.Luuac, a porttoa of the 



v^ 



• An: i, Ctlm. ..ii. ijl. f Ibid. »g9. 

t IIiiMnfriTi, jfH. Jr rUm. iitiii. It. Walloriu* boad K 
{Chnmhtry,f.ii,6)i sndDf Wumd, |-7JT < Miuy.i.ti), 
iFjft. {fM. TrMi. liil. 114.) ) BtrpiMA,La»r. 



is decomposed into sulphurous acid and oxygifn g9*. ^f*»p-ni . 
hoagh the properties of alilm afe in all cases pretty VuictiMi ^ ^ 
ly Ihc same, i( has been demonstrated by Vauquc- 
ihat iliree varielies of ii occur in commerce. The 
it supersulf'hott of alurtiina-aitd-potash ,' ihe sc- 
\, tuperiulpbate o/ altimina-anii-amtTionia ; the third 
mixture or combination of these two, and contains 

I potash and ammonia. Il is the most common of 
doubtless, because the alum makers use both urine 
miiriaie of potash to cryslallize their alum. Van- 
tin, Thcnard. and Ruard have lately analysed a num.* 

of specimens of alum manufactured in dilTerent 
Mries. Tlie result was that they all contain very 
ly the same proportion of ingredients. The meui 

II their trials was as follows : 



*_ 


t 


Acid 


30-52 


20-04 


Alumina 


10-50 


12-53 


Potash 


10-40 


10-02 


Water 
Total 


48-58 

1 00-00 


51 '41 
100*00 



^rooi the }ate analyses and e:Xperiinentl of ThenatA 



Vauqudin, ^aa. Ji I 



■rtdiu 



Tal. 



£m>11 qi». 



rhcntrd lod Roard, A-n. it Cl'im. Kx. 71. Yhc wid «» cnimited 
tin^Trf <ul[>halt of torjlen, which [hcjr couiidend is connalng onljr 
r tfi of fulpliuric unl i whcmi it cDntaini^J/ir ..'rl ; tif fvuT-M 
im|)0(tion uf thiCMidiB tbctaUeiiwo toulU 



» 



ualty conumi i \^\ 



and Roard, it appears tb&t alum itsualty cj 
njlpliatc ct' iron. lugood qualities as a moriaii' 
dyeing, depend upon ihc proportion of that nli i^. 
3cBl. The freer it i« from it the betUr. Tfacpsq 
alum examined contained about iVsn^^ pW (fa 
weight of sulphate uf iron, the imparen aboai^ 
When freed frnm tulpha'c of iron every t;«aai( 
alum tried acli exactljr la the same manner at lut. 
dani'. 

When an untinial quantity of potsuh is added to dM 
liquor, the «eiU loies its u^unl form and crjttallhai 
cubes. Thii consiimies a /ovrtb Tarieiy of ali]n,ga 
ally disiingutshed by tin- Dame ot cvbU alum, ttn 
tains nn excess of alkali. 

When the pousli is still further increased, Cbapi 
has observed thai the salt losea the property of cryn 
lisitig alrogether, and falK down in flakes. Thun 
eiilules ^ fifth variety of alum, consisting of suIpkiK. 
potash combined with a small proportion of alunnsa. 

Variety i- The sulphatei. All the varieties of dt 
are capable of combining withati additionaJ doseofil 
naina, and forming perfecily neutral compc 
posse&scd of nearly the sairc propenics^ and ( 
confounded together as one s 

It may be prepared by boiling a Solullon A 
with pure aliimiria ; the compniind, as it fonm^ f/oA 
ally piccipiiales in the form of a white pow<Ier. It w 
formerly denominated a'um saturated vnth ittrvb 
Thia salt does nut crysiaDiztf, but h^s always ihc btl 
«f a la^iclirss powder. It ii insoluble in water, UdM 



ai dose 01 u 
mpoaadiu 

■ltd Aid 

:iioii«rln 




StTLPffATSS. 



S75 



i by exposure to the air. Heat has no effect upon Ch^p. nt- 
alcss it be very violent ; and in that case pan of the 
'luid is disengaged. Sulphuric acid convens it into 
^-lluin. It is le^s easily decotnposed by other bodies than 
Several of the acids dissolve slowly its last dose 
"'if alumina, and convert it into aluna. This salt has not 
j^AMierto been applied to any use. Alum is capable 
|l tbo, as Chaptal informs us, of combining with several 
■pother bases, and of forming many triple salts, which 
■•llisve never yet been examined with attention*. 

If three parts of alum and one of flour or sugar be HombcrE'i 

. pfropoorui. 

rmclled together in an iron ladle, and the mixture dried 
:s to swell; if it be 



P: 



itill it becomes blackish and ceas 

l^'tfaen pounded small, put into a glass phial, and placed 

kin 8 sand-bath till a blue flame issues from the mouth 

of the phial, and after burning for a minute or two be 

•allawed to cool f , a substance is obtained known by the 

of Homberg's pyrophorut, which has the properly 

-of catching dre whenever it is exposed to the open air, 

; especially if the air be moist. 

I This substance was accidentally discovered by Hom- 
bcrg about the beginning of the ISlh century, while he 
was engaged in his experiments on the human fieces. 
He had distilled a mixture of human fsces and alum till 
he couldobtain nothing more from it by means of heat; 
and four or five days after, while he was taking the re- 
siduum out of ihe retort, he was surprised to see it take 
fire spontaneously. Soon after, Lemery the Young- 
er discovered that honey, sugar, flour, or almost any 




* Aiu. dt Cblm. uii. 19J. 

t CtrcjDust be ukcn not 10 keep it 100 long etpoicd lo ihe heit. 



J 



Bnimal or vegetable matter, couU be sobttiiiitEj fa 
human facta ; and afttirwardi Mr Lejojr de SoTin] 
showed tlut severs) other tails conuiniBg tulpliKi 
ttcid may be sub»ttuted lor ftlum *. Scbecle pant 
itiat alum deprived of potash is incap^le of fv^ 
p^rophoiu^ and ihRt sulphate of potaih may be h^ 
tuied for alum f. Aiid Mr Proust has thown ijn 
nanaber of neutral salts, composed of vegetihlen 
snd earths, when distilled by a strong &te ia a Ml 
leaves a rcsiduamwhich takes Qreapoouiicouil/ cat 
poture to th« air. 

These facts have Annm ■ great de^ of light on i 
Mature of Homberg's pyiophorus, uid enshlcd u 
some measiwe to account for its spontzncoDs iaiaqB 
lion. It has been ascertained, ibat part of ibenilpl 
TIC acid is decomposed during the foroMtMn of the i 
f ophorus, and of course 3 p«rt of the sikaline bsM I 
comes uncombined with acid ; and the charcoal, wli 
gives it its black colour, is evidently divided iato v 
minute panicles. It has been ascertained, that dm 
the combustion of lite pyropborus a quantity of oxri 
ia absorbed. The inSammalion is probably occHU 
by the charcoal j the mlphurct of potash alio acti 
csseotial pan. Perhaps it produces a sudden iocrc 
of temperature by the absorptioo and solidtficuite 
water from the atmosphere. 



• a« M*(quert Ktlkiury. 

t Sthccic on P,rt V\i on Pyrff^cnt. 



Sp. 12. Sulphate of T/tn'a. i 

salt was fifsi formed by Gadolin, and sftcr- 
ivas examined with more pieciuon by Ecke- 
', Vauquclin f, and Klaproth J. 

Sulphuric acid dissolves ymia readiljr, and some ca- 
Joric is evolved during the process. As ihe solution 
goes on, tlic sulphate ayatailizs% in small brUiiani 
grains. 

These crystals arc irregular, but most frequenrly, | 
according to Eckeberg, iliey have the form of li.ii six- 
n<ied prisms terminated by four-sided summiis. These 
crystals are not altered by expauire to the air. Their 
taste is astringent and sweetish, though not so much so 
as sulphate of gtucina. I'hcir colour it a light ame-' 
thyst red ; their specific gravity 2'7U1. They require 
at least 30 pans of water at the temperature ut tin" to 
diswlvc them. At a red heat they are partly decom- 
posed. 

Oxalic acid, prussiate of potash, atid the iafusion of 
auigalls, occasion a precipiiaie in the aqueous solution 
of this salt. It IS decomposed by phosphate of aoda. 

Sulphate of glucina L readily distinguished from this 
salt by its being colourless, lighter, and more soluble 
in water. 

Sp. 13. Sulphate af Glucina. 

This salt was first examined by Vauquclin, the dis- 
coverer of its base. 



• CreU*. A^nth, t 



SALTS. 

It is prepared by saturating sulphuric acid whh jt ' 
J cina. The ncid dissolves the earth readily, and ihiv. 
lution by evaporation yields small needle-form ctynl^ 
the figure of which has not been ascertained. 

It has a very sweet and somewhat flstiiDgeni tUttj 
It is very soluble tn water ; tlie solution readily n. 
somei the consistence of a syrup, but ts brought «iA 
difficulty to crystallize. When healed it uodcrgoctllK 
watery fusion, loses it* water of crystallization, xndEdli 
to powder. At a red heat it is decomposed compl 
the acid is driven dtF, and the carrh remaint ina 
of purity. The infuMon of nutgalU, when dioppc 
to the solution of this salt, occasioni a ycUowith « 
precipitate. 

Sp. 1 4. SuiphaU of Zir,o 

This ^alt was first formed by Klaproth, bat Vanqne. 
Iin has described it with more precision. It is p 
by dissolving^ zirconia in sulphuric Kid> and en 
ting the solution to dryness. 

It is usually in the form of a white potrdcr. 
however, be obtained in small needle-form crystals. It 
has no taste, and is insoluble in water. It is not aliei- 
cd by exposure to the air. It is very easily decomposed 
by heat : The acid readily flirs off, and leaves ttiecnth 
in a state of purity. This decomposition may be •£• 
complisiied even by boilmg in water; the earth pi« 
piiales, and the acid remainit in solution. Klaproiblj 
forms us, that with excess of add sulphate of xirefl 
forms transparent stelliform crystals, soluble iu « 
and having an astrlngeot taste*. 



It Vanqne- 
5 prcH|^ 



It Fiji, UlH 



:» 

I 



:^ 






SULlfHATES. 67# 

Chap. in. 
II. In so tu- 

Sp. X5> Sulphate of Lime, phates.' 

Of this salt there are two varieties. The first con- 
tains water, and is called common sulphate : The second', 
which is destitute of water, is called anhydrous sulphate. 

Variety l. Common sulphate* This salt was well 
known to the ancients under the name of gypsum ; buit 
the composition of gypsum was not known till Mar- 
graf and M acquer analysed it, and proved it to be a 
compound of sulphuric acid and lime. The salt formed 
by the artificial union of these two bodies was former- 
ly called selenite, probably from its whiteness* 

The properties of this salt were first examined with Propertia. 
precision by Bergman* It is found abundantly in dif- 
ferent parts of rhe world, so that it is seldom formed 
artificially. When pure, it is freqntiitly crystallized. 
The primitive form of its crystals is, according to Hauy, 
a right angular prism with rhomboidal base% whose 
angles are 113^ and 67^. Its integrant particles have 
the same form ; but it is more usually found crystalli- 
zed in octahedrons, in six-sided prisms, with four- sided 
summits, or lenticular. These crystals are often ex- 
ceedingly transparent. 

It has a slightly nauseous taste, scarcely perceptible^ 
except by drinking a glass of water impregnated with 
it *. It is soluble in 460 parts of water at the tempera- : 
ture of 60^t> and in 45(J of boiling water. Mr Paul 
has observed, that if this solution be saturated by pres- 



^ ■» 



f Bucholz, Gchlea** Jutr, v. 165. 



^■v 



I>M<innllt. 



sure with hydrogen gat, the mlphaie in about un 
is converted into a tulphuret %%. Tlic nit ti nelfl 
hj exponire to the »\t. It i« soluble in wlphoni 

When healed, it louis ju water oT crjvttal limit 
crepitates, and falls into a aoft white powder, 
powder, when its water hai been driven oH by i 
plicBttOD of a Ted heai, abMirbs water very rapid) 
BoUdifics ii ; at the samf lime a slight tncrnit i 
peratuTC tskci place: so that if it be formed i&to 
with water, it diies in a few minutes. In ibis : 
is called plasttr of Parii, and is mach emploj 
forming casts, £cc. in conseqaence of lliis proper 

Sulphate of lime, when exposed to a violeo 
mclls ; before the blow-pipe it gives tm opaque 
ous globule. The tein]><raiurc neccssarj* to p 
this cflect iif according to Sauasun^ 31* of V 
wood ${. 

The following Table cihibili the result of the 
cnt experiments hitherto made to aspcnain the 
tion of the coostituenls of this salt. 



C*.np«l. 




" 


T" 


t 


"»~ 


-•-r 


••- 


' 




Atid 


43 


♦3 


40 


55-75 


5e-58| 57 


5T57 






Base 


33 


5, 


32 


4V25 


43-42' *i 


42-43 


- 




Water 


=. 




22 










Total 


lonioo 


100 


100 


100 iUO 


too 


1' 














tt tli'. Mt. IT. 63. 





SULPHATES. 



«8l 



Tliete numbers, except the analysis of Chenen'x, ilo Chnp- "t_ 
* not differ much from each other. The analysts of Bu- 
ohok seems most correct. It scarcely differs from the 
result of my experiments. AnhT'l"'ii* 

I Variety 2. Aahydrous Sulphate. This variety is SulfluK. 
i {bond native in dilfi^reiil parts of ihe earth; Sweden, 
I Tyrol, Berne, &c. It seems to have been first pointed 
< out by Hauy. A specimen of it w;ts defsctibed with 
much precision by Fleuriau in the "JouTnal de Pbisi^e 
for 1 708 i and analysed by Vauquchn, who first ascer- 
tained its composition. It has since been desctibed with 
more precision by Bournon+, and a purer specimen of 
it analysed by Cheoevixl, and more lately by Kla- 
frotb j. 

It is usually crystallized. The primiiive form of 
lit crystals is a rectangular prism, having two of iis 
faces broader than the other two. It has considerable 
lustre, and the broad faces have the appearance of pearl . 
Its specific gravity is about 2'PiO. Its hardness is, 
considerable, being not inferior to that of calcareous 
spar. It usually phosphoresces when heated. It it 
transparent, insoluble in water, and in ita other proper- 
ties agrees with common sulphate. 

In the proportions of its constituent parts it coincides 
exactly with common sulphate, excepting in the absence 
af water. 

Sp. 18. Sulphate of Barjitet. 

fiais salt is found abundantly in different parts of 
■rtb, and vas formerly denominated ^om/frotu 'par. 



tiMin. An. I. ii.3<j. 



I 



(tetm Us great weigbl. lu compositum watfint ficn, ] 
I txtiied bj Gahn. 

Haay h» ihou'ii that the form of its iQtegmtfK. 
l!clei iss right. angled prism, whose bues an t\ 
wiih anglci of im;" and 781". Tlie pritniiin fi 
of ita cj^'siaU i> the same i bui it occur* a 
riciy of other foTnis. h cuinot be cr/slaUizcdb] 
Th» sah i« iriwluble in water, or ai least <m\jii 
iti 43010 liuiL-s in weight of water at the t 
of the aimosjjhere *. Sulphuric acid dissolve! it 
concentrated and boiling, but it is precipitated hfti 
adaiiion of water i. 

When suddenly healed, it breaks in pieces tod tin 
xboui with a crackling noise. Tliis phenomenon, irluch 
is called Jtcrtpilalion, is occasioned hy the sudden « 
Version of the water which it contains into i 
When heated very violendy it melts, and befbte j 
blow-pipe is converted into a white opaque glob 
According to SauMure, a heat equal to 35" Wcdgcwotd 
is icqnired to fuse it %. When formed into a ibin olu 
with Hour and water, and heated to redness, it phoiptw. 
rcsces in the dark . This was first observed in a varie^ 
ot this substance known hy the name of Bologna stoiM. 
Lemer; informs us, that the property was discovered 
hy an Italian ^ocmaker named Vincenzo CatciafDlfc 



fbnji 



t T: u> it lornii a kind of lupcnnlphaie, opible of ci 
Withring Gm Dl»rrTc<i. Mr Komr l>» iU<> n»^i>Uaned it in />itt jj __ 
V' .\j* 'I'hc (ui w» ceil kiKiwn 10 chrmiiu. llua laluiin, lam 
ttti. It but nety unpeifetlly tiiiiikJ lo the name if rapcnulphalt d 




SULPtlATlfs. 



683 



^his man found a Bologna stone at the foot of Mount Cbap. nr. 
Paterno, and it? brightness and gravity made him sup- 
pose that it contained silver. Having exposed it to the 
fire, doubtless in order to extract from it the precious 
inetaly he observed that it was luminous in the dark. 
Struck with the discovery, he repeated the experiment, 
and it constantly succeeded with him. It is evident that 
by the calcination it must be converted, at least partly, 
into sulphuret. 

The following Table exhibits the result of the differ- 
ent experiments hitherto made to ascertain the compo- 
sition of this salt. 





t 


t 


) 


II 
32 


IF 


«« 


tt 


Acid 


24 


25-lS 


31 


33 
67 


33-96 


:^4 


Base 


76 


74-82 


69 
100 


68 
100 


66'04 


66 

100 


iTotal 


100 


100 


100 


100 



tion. 



These results differ very considerably from each oth^. ' 
The analysis of Kirwan seems most correct. It is of 
great importance to have':ftn exact analysis of this salt, 
as it is by means of it that the proportion of sulphuric 
acid in different compounds is determined. 



f Chenevix, Nicholsoii's /tnrr. ii. 196. 
I Thciiard, Ann, dt Cbim, izxiL 266. 
I Vauquclifi, Ann.Je Chim. L x68. 
\ Ktrwan and Kuproth, Gchlen« ▼. 51J. 
•• Aiken, Nicholtoo'B Jwn xxii. 304. 



} Bucholc, Bfitragtt iii. 3X4 



ft Fourcroy, Iii. aj. 



L 



Sp. n. Sulphatt of StroKlura. 

This salt, for the discovery of which wc we inddi:. 
cd to Dr Hope and Mr Klaprotb, may be coonpostd ». 
tilicully by dro[>ping sulphuiic acid into suootita wa. 
ter ; in which case it has the forni of a white powdo. 
But it exists ahundantly in difTerenl pirii of the wotkl, 
usually ctystaltized in rhomboidat ptiimf. 

This salt is tasteless. It is soluble in 3S40 pirttof 
boiling water. Sulphuric acid dissolves it readily nhca 
assisted by heat, but it is picctpitatcd by tW addiiioD 
of water to the solution *. In the greater numbcT of 
its properties it has a considerable resemblance to ml. 
phate of barytei. 

It is compoMd, according to the aaalysit of Vawiw. 

lin f, of. 4^1 acid ^m 

.^4 sCrontian ^H 



According to Klaproth t, ClayEeld }, Henry ^, and 

Kirwanft, of 42 acid 

58 ftroatiaa ^| 



100 ^1 

This salt is soluble in sulphuric acid, and therefore 
forms an imperfect lupermlphate**. 



• Hope, rr«j. Edi.. i». lo. 
I Brarmf,, ir. 97. 
t Ibid, p- IJ}. 

«• Hume. FLU. Maf. xir. Jj8. 



f Jnr. it Mil. 
j Nicholnn'i . 

tf Ibid- p. s 




r 



1 



Such arc the properties of ihe sulphUcs. The fol- 
lowing Table exliibiis ihe solubility of each salt in wa. 
ter, aod the proponion of the constituents, » fu as 3ls» 
ccTtwned. The; are all insoluble in alcohol : 



Sulpbatci ol 


WiH^f. 


'•■-'— 1 


Arii 


a..c. 


WMcr. 


Ammonia 


50 


100 


2605 


51 


Magne.ia 


100 


100 


5TP2 


182-8 


Lime 


0-22 


100 


-6-10 


55-8 


Soda 


35 


lOO 


78-3 2 


246-6 


Poiash 


e-2 


100 


1 to 


SO 


Scroniiati 


0-0 


lOU 


133 




Baryteff 


0-0 


100I203 





"The genos sulphates contains several salts of consi- 
derable importance. 

1. Sulphate of potash was formerly used in medi- 
cine ; but on account of its disagreeable taste and Httle 
sulubitily it is now laid aside. Apothecaries, indeed, 
sometimes »se it to facilttaie the powdering of vegetable 
cathartics. To the alum-makers it is of considerable 
importance, as it eaters into the composition of alum, 
ivbieh cannot be obtained crysEallized without potash 






£. Sulphate of sodti is one of ihe most CMDcnaoif i 
all tlic cooling furgativa, as ihcy have b«o tcmcdj 1 
immense quantities being nnniwlljr mnia&cturad ai I 
consumed. 

3. Sulphate of ammonia is aometimea cmploied la ^ 
chemical aoalysci. Thus it w«s used with adTnui|c 
by Ualchetl in examining the moiybdaii of Itai. 

4. As great quantities of the lulphai 
are prepared for commercial purposes, ll 
bably in common use on the contiocnt as a 
Its intensely bitter taste has brought it into duute ia 
this country. WEial is »oId by apothecaries tUKktllx 
name of Epsom sah is often nothing clae than tulphaie 
of »oda in small irregular crystals. 

5. Sulphate of lime is much used ss a cement, i 
the name oi ptcuter of Pari/. It is employed also fii 
moulds, and for casting into statues, &c. Ii is fim 
heated, in order to deprive it of its water. In this uate 
it forms with water &lii|ui(I paste, which in a few mt- 
iiuics becomes solid iu consequence of the combination 
of the water with the sulphate. It constitutes the chief 
ingredient uf ntueco ; and is in many places used at i 



/ """■ 

e of reapw^u 

le salt is p^ 

s a potgani^ 
isute ia 
Kktilx 
ulphaie 

also 6? 



6, The sulphates of barytes and slroDtian are not 
apphcd to any useful purpose directly i but they fur- 
nish almost all the- barytes and strontlan which tlie 
chemists employ. 

7- But ihe most important of all the sulpbat 
undoubtediy alum, which is applied by maniifac 
to too many u^cs fur a complete enumeration. To Uia 
dyer and calico printer this salt is indispcnsiblci ai 
alumina, its earthy base, forms oue of the best of all tbc 
morJantf, or substtinccs which have llie propt(Qr«ffiXa 



IphateaiJ 
ifactunM 



SULPHATES. 687 

lag colouring matters in cloth. It is used by the tan- Chap. ni. 
ners in' the preparation of leather. Indeed, some kinds 
of leather may be considered as nothing else than skins 
altered by being steeped in a solution of alum in water. 
It is often very useful in clarifying liquors, froqi the 
property which alumina has of forming an insoluble 
precipitate with many vegetable substances. Surgeons 
sometimes take advantage of the properties of this salt, 
and use it as an astringent or styptic ; but it would be 
too tedious to enumerate the purposes to which this salt 
is applied by paper-makers^ goldsmiths, candle-makers^ 
bookbinders, &c. 



END OF THE SECOND VOLUME. 



Printed by John Bkown,? 
Anchor Cloie, Edinburgh. 5 



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