50 On definite’ Proportions. 
that, like the mineral acids before mentioned, they cannét be ex- 
hibited in a separate state. 
We have also seen, that both the citric and the oxalie acids 
contain a portion of water which may be expelled, and which 
may he considered as water of crystallization, while the acid 
remains combined with another portion of water, which com- 
pletely assumes the place of a base, and can only be expelled 
by a stronger base. We may properly consider these combina- 
tions with water as salts, in which water is the base, and stands 
precisely in the predicament of the weaker bases among the me- 
tailie oxides, which are capable of combining beth with acids 
and with other bases. If we consider the water which escapes 
from the oxalic acid during its efflorescence as water of crystal-- 
lization, it contains twice as much oxygen, as the portion of the 
water, which is to be considered as the base of the combination. 
It is not probable that these determinations can be liable to 
any error from the presence of water in the oxalate of the prot- 
oxide of lead: for from 5 gr. of well dried oxalate of lead, pro- 
perly burnt in close vessels, 1 obtained in two experiments ouly 
from 077 to -O9 gr. of water, together with a quantity of car- 
bonie acid which afforded 3-708 of carbonate of lime. If we 
calculate the composition of the oxalic acid from the analysis of 
the oxalate of the protoxide of lead, the carbonate of lime, the 
carbonic acid, and water, this acid must consist of 34:9 of car- 
bon, nearly 1 of hydrogen, and 64:1 of oxygen. But we have 
seen that 100 parts of oxalic acid unite with so much of a base 
as contains 212 parts of oxygen, and 21:2 x3=63'6. We 
may therefore consider it as proved, that the oxalic acid must 
contain three times as much oxygen as the base by which it is sa- 
turated. Finally, we ‘* have found, that” the water contained 
in the crystallized oxalic acid contains exactly as much oxygen 
as the acid itself. 
It is true that these analyses of the vegetable acids differ con- 
siderably from those of Gay-Lussac and Thenard ; probably on 
account of the water united withthem. For, if we subtract 
from the acid of the tartrate of lime as much water as contains 
twice as much oxygen as the lime, we find the capacity of the 
acid for saturation such as is determined by my experiment gn the 
tartrate of lead. The same is true of the citrate and oxalate of 
lime, if we deduct from them as much water as contains a quan- 
tity of oxygen equal to that of the lime. With this correction, 
the analysis of the oxalic acid agrees pretty well with mine ; but 
there is still a considerable variation in our analyses of the tar- 
taric acid ; and time must decide which is the least inaccurate. 
B. Com- 
