copper copper.
nickel nickel.
arsenic arsenic.
bismuth bismuth.
mercury mercury.
antimony antimony.
silver silver.
_Note._--All these were unknown to the ancient chemists.--A.
SECT. XLIII.--_Observations upon Sebacid Acid, and its Combinations._
To obtain the sebacic acid, let some suet be melted in a skillet over
the fire, alongst with some quick-lime in fine powder, and constantly
stirred, raising the fire towards the end of the operation, and taking
care to avoid the vapours, which are very offensive. By this process the
sebacic acid unites with the lime into a sebat of lime, which is
difficultly soluble in water; it is, however, separated from the fatty
matters with which it is mixed by solution in a large quantity of
boiling water. From this the neutral salt is separated by evaporation;
and, to render it pure, is calcined, redissolved, and again
cristallized. After this we pour on a proper quantity of sulphuric acid,
and the sebacic acid passes over by distillation.
SECT. XLIV.--_Observations upon the Lithic Acid, and its Combinations
with the Salifiable Bases[53]._
From the later experiments of Bergman and Scheele, the urinary calculus
appears to be a species of salt with an earthy basis; it is slightly
acidulous, and requires a large quantity of water for solution, three
grains being scarcely soluble in a thousand grains of boiling water, and
the greater part again cristallizes when cold. To this concrete acid,
which Mr de Morveau calls Lithiasic Acid, we give the name of Lithic
Acid, the nature and properties of which are hitherto very little known.
There is some appearance that it is an acidulous neutral salt, or acid
combined in excess with a salifiable base; and I have reason to believe
that it really is an acidulous phosphat of lime; if so, it must be
excluded from the class of peculiar acids.
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