On definite Proportions. 373 
indicating a little more oxygen in the carbonic acid than 
the determination of M. Gay-Lussac ; but the variation is 
immaterial: future experiments will perhaps inform us on 
what this variation depends. In the experiment on the 
carbonate of the protoxide of lead, the quantity of carbonic 
acid was in all probability augmented by a little moisture ; 
for, when the experiment is performed in a small glass re- 
tort, a slight deposition of aqueous vapour always appears 
in the neck of the retort, and disappears immediately with 
the carbonic acid gas. 
It appears to me that we are right in considering the car- 
bonates of lime of baryta, and of the protoxide of lead, as 
neutral combinations: and in order to avoid inconsistency, 
we must denominate al] the carbonates, in which the acid 
contains only twice as much oxygen as the base, neutral 
salis, and the combinations completely saturated with car- 
bonic acid supercarbonales. For, if we attempt to infer, for 
example, the component parts of the neutral carbonate of 
soda from the analogies of the sulphates of baryta and soda 
and the carbonate of baryta, we obtain a result agreeing 
with the common carbonate of soda. 
V. Tue Acips oF Puospuorus. 
The phosphoric acid saturates so much of any Lase, that in 
the phosphates. as in the carbonates, the acid contains exactly 
twice as much oxygen as the base. 
a.) Four grammes of phosphate of baryta were dissolved 
in nitric acid, and a precipitate was obtained by means of 
the sulphate of potass: when ignited, it weighed 4°397 gr., 
which contain 2°888 gr. of baryta, and leave 1112 gr. for the 
phosphoric acid in the 4 gr. Hence the phosphate of baryta 
consists of Phosphoric acid 27°8 100°0 - 
BPG i. megtdin. ni ae 259°7 
4.) I dissolved five grammes of pure lead in nitri¢ acid, 
and dried the solution. The neutral nitrate of the protoxide 
was dissolved in water, to which neutral phosphate of am- 
monia was added: the phosphate of the protoxide of lead, 
thus obtained, after having been well washed and ignited, 
weighed 6°8 gr.; and no trace of lead was discoverable in 
the fluid by means of sulphuretted hydrogen, Now 5 gr. 
of lead require -385 of oxygen, in order to form a prot- 
oxide: hence 5°385 gr. of the protoxide had united with 
1415 of phosphoric acid: and the phosphate of the prot- 
exide of lead consists of 
Phosphoric acid...... 20°809 100°00 
Protoxide of lead%.... 79°19) 380°56 
Aa3 These 
