C H E M 
very little oxygen, not ftifficient to impart to it the na¬ 
ture of an acid, and in this it is nothing more than an 
oxyd : fuch is fulphur coloured red or brown, by expo- 
fure to the air, and a degree of heat inadequate to produce 
inflammation; when it is oxyd of fulphur: 2dly, Con¬ 
taining- more oxygen than in the preceding cafe, and 
enough to become an acid, though weak ; as in the lid- 
phurous acid : 3dly, Poffefling ftill more oxygen than in 
the fecond inftance, and having acquired powerful acid 
properties; fuch is the fulphuric acid : 4-thly, Conjoined 
with a.larger dole of oxygen than is necefl'ary to conlli- 
tute a powerful acid, an acid in ic ; when it is termed an 
oxygenated acid, or even luperoxygenated. 
From the coniiderations above enumerated, it follows, 
that we have two modes of forming at will acids with 
different proportions of oxygen. One is, to combine the 
radicals with fitch determinate quantities of oxygen as 
are necefl'ary to convert them into the date required, as 
is done with fulphur, phofphorus, or arfenic.: the other, 
to extract from acids containing the greateft poffible 
quantity of oxygen, different proportions of this princi¬ 
ple, by means of combultible fubflances which abl'orb it 
with great avidity. The latter method, founded on the 
affinity of oxygen for different combultible fubflances, is 
frequently employed with fuccefs for the complete de- 
compofition of acids, by depriving them of all the oxygen 
iheycontain. It is in this way, that acids inflame com- 
budible fubflances. To produce this effeft it is fufficient 
that the acids employed do not contain oxygen in a ftate 
of folidity, and that the inflammable matter brought into 
contaft with it will abl'orb it in a more folid ftate than 
that in which it fubflfts in the acid. But thele conditions 
being reqjuifite, inflammation by no means takes place in 
all decompofitions of acids by combultible fubflances. 
Hot charcoal is fuccefsfully uled to decompofe all acids 
fufceptible of decompofition ; but it is not the only com- 
bultible fubftance that will anl'wer the purpol'e ; for molt 
metals, phofphorus, fulphur, and hydrogen in a dry and 
folid ftate, as itexills in vegetable compounds, poflefs the 
fame property. 
All the acids, the fpecific nature of which is owing to 
their particular radicals, as has been already faid, ma'y 
be divided into four clafles, according to the nature of 
their bafes being known or unknown, Ample or com¬ 
pound. The firft clafs includes acids with known and 
Ample radicals, or fuch as are formed by the union of 
indecompofable combultible fubflances with oxygen. Its 
fpecies are the following : Sulphuric acid, nitric acid, 
carbonic acid, phofphoric acid, arfenic acid, tungftenic 
acid, and molybdenic acid. The fccond clafs comprifes 
acids with radicals that are unknown, but ftrongly fuf- 
pedted of being Ample. In it may be reckoned the mu¬ 
riatic acid, fluoric acid, and horacic acid. In the third 
clafs may be ranked acids with binary compound radi¬ 
cals. Such are all the vegetable acids, the common ra¬ 
dical of which'is a compound of hydrogen and carbon. 
In this clafs the fuccinic acid lhould alfo be placed. To 
the fourth clafs belong all acids of which the radicals are 
at leaft triple compounds. In this are comprehended the 
animal acids, the radicals of which are combinations of 
carbon, hydrogen, and azot. . 
Not only is each of the clafles in the preceding fedtion 
diftinguifnable by general charadters inherent in it, but 
each individual acid alfo poffefles properties by which it 
is charadterized, and which prevent its being confounded 
with any other. And thefe properties may even be de¬ 
noted by Ample and eafy expreffions, by phrafes Amilar 
to thofe which naturalilts have learnt from Linnaeus to 
employ. A fketch of this method we fhall prefently 
exhibit. 
AH acids with Ample and known radicals are capable 
of being decompofed by combultible bodies, which they 
burn with more or lefs rapidity, and are thus reduced to 
their radicals. It is by means of this decompofition, 
that the nature of their radicals becomes known. We 
Vox,. IV, No. 186. 
[ S T R Y. 161 
can alfo form them from their conftituent principles, by 
uniting their radicals with oxygen. Acids with un¬ 
known radicals, which are fufpedted of being Ample fub- 
ftances from ftrong analogy, have no other claffic charac¬ 
ter than thofe of being in fufceptible of decompofition 
by means of combultible fubflances, and incapable of be¬ 
ing formed by art. Acids with binary radicals, or vege¬ 
table acids, are diftinguilhable by the following charac¬ 
ters. 1. They are all decompofable by a ftrong Are and 
a fufficient addition of oxygen. 2. I11 this decompofition. 
they afford water and carbonic acid, formed by the dis¬ 
junction of their hydrogen and carbon, each of which 
unites feparatelv with a portion of the oxygen. 3. They 
are decompofed fpontaneoufly and (lowly in a temperature 
above 53 0 , if diffolved in water. 4. They cannot be. 
decompofed by any known combultible body, their radi¬ 
cal being compounded of two fubflances which have the 
Itrongeft attradtion for oxygen of any with which we are 
acquainted. 5. They are convertible into each other; 
which is owing to the difference between them confining 
folely in the proportion of their three conftituent prin¬ 
ciples. 
Acids with ternary radicals, and thofe wdiich are ftill 
more compound, or animal acids, though the leaft known 
of all, poflefs fome properties which may be deemed claffic 
charadters. Such are thofe of affording ammoniac when 
decompofed by fire, and furnifiling pruffic acid on the 
proportion of their principles being changed. To thefe 
claffic charadters their fpecific charadters may be added, 
thus attempting a language analogous to that of the bo- 
tanift and zoographer. 
Acids of the firft clafs , or ‘with fimple and known radicals .—• 
1. Sulphuric acid, formed of fulphur and oxygen by the 
combuftion of fulphur, inodorous, twice as heavy as wa¬ 
ter, very cauftic, lefs volatile than water, affording ful- 
phurous acid gas and fulphur, on being decompofed by 
red-hot charcoal, metals, See. and forming fulphats with 
earths, alkalis, and metallic oxyds. 
2. Sulphurous acid, having a powerful flnell, very vo¬ 
latile, gafeous, deftrudtive of blue vegetable colours, and 
removing Itains produced by thefe colours on white, gra¬ 
dually attradling oxygen from the air, and feveral acids 
or oxyds, and forming fulphits with earthy and alka¬ 
line bafes. 
3. Nitric acid, liquid, white, cauftic, of a ftrong and 
naufeous fmell, formed of azot and oxygen, inflaming 
fulphur, charcoal, zink, tin, and oils, yielding to com- 
bullible bodies various portions of oxygen, and thus 
giving birth to nitrous acid, nitrous gas, or nitrous oxyd, 
aeltroying colours, burning and turning yellow vegetable 
and animal l'ubftances, converting them into acids, de- 
eompofing ammoniac, produced by putrilying animal 
matter, forming nitrats with earths and alkalis, remain¬ 
ing (lightly united with metallic oxyds, and tending to 
acidify them. 
4. Nitrous acid, the fame as nitric acid, except in hav¬ 
ing a fmaller portion of oxygen, red or orange coloured 
in the ftate of gas, very volatile, depriving vegetables of 
colour, becolning blue and green on the addition of wa¬ 
ter, turning yellow nitric acid, to which it is united in 
different proportions, yielding nitrous gas on the contadt 
of combultible Jubilances, and forming nitrits with earths 
and alkalis. 
5. Carbonic acid, formed of twenty-eight parts of car¬ 
bon with feventy-two of oxygen, a gas heavier than air 
and difplacing it, filling fubterraneous cavities, dilen- 
gaging itfelf from liquors in a ftate of vinous fermenta¬ 
tion, extinguifliing lighted candles, killing animals, red¬ 
dening only light vegetable blues, precipitating chalk 
from lime-water, re-dilfolving the chalk in the water, 
mineralizing acidulous waters, baryt, lime, copper, iron, 
and lead, in quarries and mines, forming carbonats with 
earths, alkalis, and metallic o.xyds, decompofable by 
phofphorus alone, and when it is united to alkaline bales, 
particularly foda in the ftate of carbonat, 
T 1 6. Phofphoric 
