C H £ M I 
Genus”XXII. Oxalats : May be characterized by 
their tendency to form acidules of difficult folution, and 
their property of decompofing all calcareous falls. 
Genus XXIII. Camphorats : Too little known to 
have generic characters affigned them : they are to be 
diftinguifhed by the prefence of tlie camphoric acid, and 
the recognition of its properties, when leparated. 
GenusXXIV. Pyromucits : Similarly circumftanced 
with camphorats. 
Genus XXV. Pyrouignits : The fame may be faid 
of thefe. 
Genus XXVI. Pyrotartrits : Thefe rank with the 
three preceding genera. 
Genus XXVII. Ac tT at s : Yet too little diftinguifh¬ 
ed from acetits : evolving, when decomposed by mineral 
add, a very Itrong and pungent white vapour. 
Genus XXVIII. Acetits : All recognizable by their 
acid difengaged by means of {harper acids. 
Genus XXIX. Lactats: Very little known: their 
acid, leparated by. others, can alone characterize them. 
Genus XXX. Saccholats: As the laCtats : unknown. 
Genus XXXI. Sebats: Emitting the white vapour and 
acrid fmell of febacic acid on the contaCt of the Itrong eft 
mineral acids.- 
Genus XXXII. Lithiats : The weakeft of all falts 
in their attractions, being decompolhble even by the car¬ 
bonic acid. 
Genus XXXIII. Formiats: Very little known, and 
recognizable only by means of their acid. 
Genus XXXIV. Bombiats : Similarly circumftanced 
with the formiats. 
Genus XXXV. Prusstats : Completely characterized 
by their property of forming Pruffian blue with folutions 
•of iron. 
To determine the fpecific characters of nearly two 
hundred and forty-five fpecies contained in thefe thirty- 
five genera, they would require to be profoundly ftudi- 
ed, and in this refpeCt fcience is yet but little advanced. 
While our knowledge is thus defective, it is of import¬ 
ance to indicate at leaft the path we ought to purfue, to 
complete the hiftory of thefe compounds, and to afcer- 
tain with.precifion the method of inveftigating their pro¬ 
perties. Each compound earthy or alkaline fait prefents 
to our obfervation, ill. Figure, and the varieties of that 
figure. This ought to be defcribed geometrically : the 
inclination and degrees of its angles, the primitive for¬ 
mation of the cryftals, the interior form, their diffeftion, 
and the laws of decreafe which determine their varieties, 
fiiould be detailed, zdly. Its exiftence by art or nature, 
with a comparifon of the native and artificial fait, jdly, 
Tafte. 4tbly, The aftion of fire; whether it be null, 
filling, vitrifying, fubliining, or decompofing, See. 5thly, 
That of light. 6thly, The influence of the air; whether 
it be null, or impart water to the cryftals, or elicit water 
from them. 7thly, The union with water, the quantity 
neceflary to difl’olution at different temperatures, the ca¬ 
loric abforbed or evolved, the cryftallization produced 
by refrigeration or evaporation. Stilly, The attraction 
of earths which modify the fait, deccmpole it, produce 
no change in it, or unite with it to form a triple fait. 
91 h 1 y, The effeft of alkalis on it; whether null, decoin- 
pofing, or fometimes combining with it, fo that a triple 
fait is formed, lothly, The comparative aftion of acids 
different from that which it contains, decompofing the 
fait, changing its nature, or producing in it no altera¬ 
tion. nthly, The operation of other neutral falts on 
it; which may produce a complete union, forming a 
triple fait; a double decompofition, by an interchange 
of acids and bafes ; a precipitation, in confequence of 
their attraction for water; or no alteration whatever, 
iathly, The diffolubility or indiffolubility of the fait in 
alcohol. 13thiy, Its alterabiiity or unalterability by 
by means of charcoal, which may difeompofe its acid, 
or leave it untouched, iqthly, The influence of vegetu- 
Vol, IV. No. 186; 
S T R Y. 165 
tion and fermentation on the fait. 15th, and finally, Its 
aftion on the animal economy. 
If all thefe queftions were anfwered with precifion, in 
the prefent ftate of chemiftry, the hiftory of earthy and 
alkaline compound falts would not only be complete, but 
would throw confiderable light on various phenomena of 
nature and art, which ftili remain plunged in great obfeu- 
rity. Some faline combinations of an acid with two bafes, 
particularly magnefia and ammoniac, are already known: 
thefe compounds bear the name of trifules, or triple falts; 
but a far greater number exifts, of which we are not fuf- 
ficiently aware, and which demand all the attention 
that can be paid them by chemiffs'. The earth conceals, 
both at its fufface and in its ftiperficial cavities, faline 
compounds differing from thole which art produces by 
the limultaneous exiftence of two bafes, or even of two 
acids: borat of lime and borat of magnefia have already 
been found cryftallized together in cubic quartz, phol- 
phat of lime, and fluat of lime, in the earth of manr.it- 
rcch and the eftremadura ftone, Sec. Thefe data luctei: - 
fully lead to the knowledge of native falts: the cryftal¬ 
lization and purification of ufeful falts : the phenomena 
of folutions : the precipitation and preparation of alumin, 
magnefia, &c. the attraftion of lime, potafli, foda, and 
ammoniac, for acids: the formation cf neutral falts by 
nature: all the details of halotechny: the preparation of 
the nitric, muriatic, boracic, and leverai other acids. 
THE OXYDATION AND DISSOLUTION OF METALS. 
Metals have already come under confideratioir in 
page 159, as indecompof'ed or Angle combuftible bo¬ 
dies ; and have been charafterized by their molt linking 
properties. But thefe general obfervations. are not fufli- 
cient: the important parts performed by thefe fubftan- 
ces, in the phenomena of nature and the proceffes of the 
arts, require, that they fnouid. be feparately examined, 
and with fufficient minutenefs to enable us to appreciate 
the whole of their influence. Though metals are capa- 
b!e of uniting in their metallic ftate with each other, 
with fulphur, with phofphorus, with carbon, and with 
combuftible fubftances in general, it is much more com¬ 
mon to fee them combined with oxygen previous to their 
union with other bodies; or, in other words, for them 
to enter into the greater number of compounds of which 
they conftitute a part, it is neceflary, that they firft unite 
with oxyen, or be converted into the ftate of burnt bo¬ 
dies. Accordingly, all the lingular phenomena difplayed 
by metals in their combinations, and the changes of form 
they undergo, are'owing to their attraftion for oxygeii, 
and the different proportions in which they contain this 
principle. Though there are various circumftances under 
which metals may be united with oxygen, they may be 
reduced in general to three. The firft is the contaft of 
air, afiifted by caloric; the fecond is owing to the decom¬ 
pofition of water; the third, to that of acids. In this 
triple view the oxydation and diffplution of metals are 
here to be cohfidered. 
All metals heated in the air, and railed to a tempera¬ 
ture more or lefs high, are fuf'ceptible of burning with 
a vivid flame, great heat, and a true deflagration, either 
previous or fubfequent to their entering into fufion ; 
thus they ablorb oxygen in a ftate of greater or lefs fo- 
lidity : thofe which oxydate flowly, and without percep¬ 
tible inflammation, equally difengage light and caloric 
from the vital air, hut'in fo fmall a quantity at a time, 
that they are not rendered fenfible to our organs. Ele¬ 
vation of temperature favours the abforptiOn of the oxy¬ 
gen of the atmofphere by metals, and renders the com¬ 
bination of this principle with thefe combuftible bodies 
more folid. While there are fome metals which never 
burn in the air, except at a very high temperature, as 
gold, lilver, and platina, there are others that burn at all 
temperatures, even the loweft, and with great prompti¬ 
tude j as munganefe, which oxydates, and falls into pow- 
U. u dcr. 
