374 On definite Proportions. 
These results are also confirmed by calculation: for 100 
parts of sulphuric acid saturate 191°427 of baryta, and 279 
of protoxide of Jead, and 100 of phosphoric acid 259°7 of 
baryta; whence we have 191°497 :279=259'7: 378°51. 
The slight difference amounts only to 7,45 of the weight 
of the salt, 
Now 360'56 parts of the protoxide of lead contain 27°21 
of oxygen, which, doubled, gives 54:42. Consequently, 
according to this calculation, 100 parts of phosphoric acid 
should consist of 45°58 of phosphorus and 54-42 of oxy- 
gen. The late Mr. Rose found that 5 gr. of phosphorus 
absorb 5°555 of oxygen, or that 100 parts of phosphoric 
acid consist of 47°62 of phosphorus, and 52°38 of oxygen. 
If we take into consideration the moisture unavoidably ad- 
hering to the phosphorus when it is weighed, the analysis 
of Mr. Rose wil! agree very well with the computation. 
This gentleman attempted also to convert a determinate 
quantity of phosphorus into phosphate of the protoxide of 
lead, and obtained from 50 grains of phosphorus 481 of - 
this combination, If this experiment were perfectly cor- 
rect, the phosphorus must take up less than its own weight 
of oxygen, or, calculating upon the analysis of the phos- 
phate adduced by Mr. Rose, the acid should conisist of 
equal parts of oxygen and of phosphorus: so that the two 
experiments, which give 22°3 for the acid contained in 100 
parts of the phosphate of the protoxide of lead, and 481 for 
the phosphate obtained from 50 parts of phosphorus, are 
inconsistent with each other, and lose their pretensions to 
accuracy. ~ ; 
With the phosphorous acid 1 am not acquainted from my 
own experience: but it is very possible that this acid also 
may be found to contain twice as much oxvgen as the base 
by which itis saturated. Jn this case it would follow that 
such salts when exposed to heat in close vessels, should af- 
ford phosphorus, and leave a neutral phosphate behind : 
which, according to Fourcroy and Vauquelin, is the actual 
result of the experiment: and itis not probable that so ac- 
curate a chemist as Vauquelin would have overlooked the 
excess of base, if the phosphites had been decomposed by 
heat in the same manner with the sulphites. Consequently 
the phosphites must stand in the same relation to phos- 
phorus, as the hyperoxymuriates to oxygen; [that is, with 
regard to the operation of heat only. ] 
VI. THe Actps of ARSENIC. 
We have several good analyses of the arsenic and arses 
pious 
—s = < 
— ee 
