the Combinations of Phosphorus. 453 
phosphoric acid in phosphate of potassa, which may be de- 
duced from the experiments, page 449, it appears more conve- 
nient to represent the proportional number, or equivalent of 
phosphorus, by 45, or 45°2, than by 22°, or 22-6, which gives 
facility in adopting either hypothesis of the composition of hy- 
pophosphorous acid. If it be supposed a simple compound of 
oxygen and phosphorus, the series of proportions in the acids of 
phosphorus will be 
Hypophosphorous acid, Phosphorus. 45 Oxygen 15 
Ebesphorous,acid,.:. 0, sia) iae oo Oxygen 30 
TAM PROUIC ACI ro. 504, Fe a), pee te Oxygen 60 
acid 263... Phosphuretted Hydrogen | prop. 53 
I shall conclude this paper by a few incidental observations on 
the compounds of phosphorus. 
M. Dulong states that no phosphorous acid is formed when. 
phosphorus is burnt in excess of oxygen or atmospheric air ; as, . 
he says, [ have asserted. I cannot find that I have any where: 
made such an assertion 5 but notwithstanding what M, ‘Dulong 
pretends, the assertion is true, as the following experiment will 
prove. Half a grain of phosphorus was set fire to in a retort 
containing 16 cubical inches of common air; the acid products 
were washed with distilled water, and passed through a filter, and 
evaporated. When the acid became nearly dry, small globules 
of phosphuretted hydrogen were disengaged from it, indicating 
the presence of phosphorous acid. The experiment was repeated 
two or three times, care being taken to separate the red powder 
which has been considered as an oxide of phosphorus, and al- 
ways with the same result. 
Whenever phosphorus is inflamed, and suffered to become 
extinguished in oxygen gas in excess, unless the produet is 
strongly heated after the spontaneous combustion is over, an 
acid, of which the hydrate produces phosphuretted hydrogen by 
heat, is always found in the products; and this acid is probably 
produced by the action of the solid phosphorus on the phospho- 
ri¢acid in contact with it. This fact, and the circumstance, 
that much phosphorous acid is produced by the combustion of 
phosphorus in rare air, renders it almost certain that the.phos- 
phorous acid is a direct combination of phosphorus and oxygen, 
and destroys an idea which might otherwise be formed from the 
phenomena of the decomposition of its hydrate, namely, that 
it is a compound of three proportions of phosphoric acid, and 
one of phosphuretted hydrogen. 
M. Dulong and M. Berzelius speak of freeing phosphorane, 
or the liquid chloride of phosphorus, from phosphorus, by di- 
stillation. In experiments made in the laboratory of the Royal 
f 3 Institution, 
or hypophosphorous ¢ Phosphoric acid 2 proportions 210) 
