S 34 > Sir H. Davy’s new experiments on some 
it contains water, so that it is a hydrated phosphoric acid. In 
carefully conducting the experiment, I find likewise, that a 
small proportion of water is given off with the perphosphu- 
retted gas. I shall give the results of an experiment: 17.5 
grains of hydrophosphorous acid were decomposed by heat in 
a small glass retort carefully weighed ; 6.5 cubical inches of 
elastic fluid were generated, and the loss of the retort was 4 
grains. Now, if it be assumed that the hydrate of phosphoric 
acid * remaining equalled 13.5 grains, and that it contained, 
according to the law of definite proportions, 1.88 of water, 
and that the bi-phosphuretted gas weighed 1.937, and con- 
sisted of 1 .6446 phosphorus, and .2924 hydrogen ; then the 
oxygen in the phosphorous acid will be to the phosphorus as 
44 to 66, which is as near a result as can be expected. 
For 4 proportions of phosphorous 
acid are - - 300 or the double 150 
and 10 of water - -170 
or 
85 
which together amount to - 470 
or 
2 35 
which form 3 proportions of phosphoric acid 
315 
or 
157-5 
with 3 of water to form the hydrate 
5 i 
or 
2 5-5 
3 66 
183.0 
4 of water decomposed, of which the hydro- 
gen is 8, to form with 45 of phosphorus 
phosphuretted hydrogen 
53 
or 
26.5 
3 of water given off - - - 
5 i 
or 
2 55 
making - 
47 ° 
or 
2 35 - 
* I proved it to be a hydrate by heating it with magnesia, when abundance of 
water was given off from it. 
