A Manual of the Chemistry of the Carbon Compounds

TUB CARBON COMPOUNDS. 27
= 2*1 parts, or 2 atoms of hydrogen,
v oA
no » 217 parts, or 2 atpms of silver.
In the yellow salt we find—
--•!•,*," = 1-05 parts of hydrogen,
62 '° x ^ 4 = 327-5 parts, or 3 atoms of silver.
io-y
From this we conclude that the acid is tribasic, and that the
formula C7H4O7 represents a molecule; and, as a further confirmation,
we find that we also know acid salts containing only one atom of a
monad metal The molecular formulas of the above compounds are
therefore— Meconic acid . . . . . C7H4O7
White salt C^AggO,
Yellow salt CjHAggO,
A great number of carbon compounds containing nitrogen are
bases, which combine with acids like ammonia; some are monacid
bases, others are polyacid. To fiud the molecular weight of such a
compound, we have only to ascertain the quantity of acid contained
in an anhydrous normal salt, or, better still, to find the quantity, of
platinum present in the double salts, formed by the combination of
the hydrochloride "with platinic chloride, and which, like ammoniumplatinic
chloride, contain two molecules of hydrochloric acid for each
molecule of platinio chloride.
Caffeine is a monacid base; its platinum double salt contains two
molecules of caffeine, and two molecules of hydrochloric acid, combined
with one molecule of platinio chloride; 100 parts of this compound
leave on ignition 24-6 per cent, of platinum; consequently, to find
out in how much of the platinum salt one atom or 197*5 parts of
platinum are contained, we have—
197-5 xlOO_ 9
24-6 '
From thU we find the molecular weightof vaffeine by the equation—
2» + (2 x 36-5) + 339-5 = 806-9
x = 197-2.
As we know the percentage composition of this base, we can easily
find its molecular formula:—
197-2x49-5 ana „ .
——Y7>»5— ~ 97'6 of carbon.
— 7 '\*0 5 ' 2 - 103 of hydrogen.
197-2x28-9 KIyft , ..
JQQ— a 570 of nitrogen.
1072 x 164 rtO„ .
j-00 = 32-3 of oxygen.