330 Sir H. Davy’s new experiments on some 
If 13.1 be considered as the quantity of hydrate of potassa 
required to neutralize the phosphoric acid formed in the last 
experiment, and the 54.9 of hydrate remaining, be supposed 
to contain 43 grains of potassa, then the chlorine required to 
expel the oxygen from the potassa would be rather more 
than 40 cubical inches. 
We owe to the ingenuity of M. Dulong the discovery of an 
acid, which he names the hypophosphorous acid, and which he 
supposes to contain half the quantity of oxygen in the phos- 
phorous acid. I have satisfied myself as to the correctness of 
his views respecting the existence of this acid, and the pro- 
perties of its compounds ; but I cannot regard the method he 
has adopted for its analysis as entitled to confidence. He takes 
a given quantity of hypophosphite of soda, acts upon this by 
chlorine, converts the excess of chlorine into muriatic acid, 
precipitates by nitrate of silver and earthy salts, and from the 
comparison of all these data, in which some substances of 
uncertain composition may be concerned, draws his con- 
clusions. 
I have found that the neutral hypophosphite of barytes, 
when acted on by heat in close vessels, is converted into acid 
phosphate of barytes, disengaging an elastic fluid, which is 
almost entirely the hydrophosphoric gas, or phosphuretted 
hydrogen saturated with phosphorus. I say almost entirely , 
because in the beginning of the process, a little gas sponta- 
neously inflammable is produced, and a minute quantity of 
moisture appears : and when the heat is raised tc redness, a 
very little phosphorus is p educed, probably from the decom- 
position of a part of the phosphoric gas . Now supposing the 
quantity of phosphoric acid in phosphate of baryta known. 
