the Combinations of Phosphorus. 449 
it contains but 17°67 of soda to 20°33 of acid; whereas it 
ought to contain, according to the proportion indicated by my 
experiments, (ifneutral,) nearly an equal weight of soda. M. Ber- 
zelius mentions several combinations of baryta and lime with 
phosphoric acid, of which only two approach to a correspond- 
ence with the number | have given for phosphorus; that con- 
taining 45-5 of acid to 48°7 of lime; and that containing 39°1 
of acid to 60-8 of barytes. New researches are required to 
explain the anomalies presented by the phosphates. 
I shall give three experiments on the quantity of hydrate of 
potassa necessary for saturating given quantities of phosphoric 
acid made from given weights of phosphorus. 
Eighteen grains of phosphorus converted into phosphoric acid 
by combustion in oxygen, required for its saturation 47 grains of 
dry hydrate of potassa. 
5-7 grains of phosphorus converted into acid, required 14*7 
of hydrate of potassa. 
Five grains of phosphorus converted into perchloride, de- 
manded, to produce perfect neutralization, 65 grains of hydrate 
_ of potassa. 
These three experiments agree so well with each other, and 
with the proportionate number gained from the absorption of 
chlorine and oxygen by phosphorus, that it is impossible not to 
put confidence in them. 
If 13:1 be considered as the quantity of hydrate of potassa 
required to neutralize the phosphoric acid formed in the last ex- 
periment, 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 cu- 
bical 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 phospho- 
rous acid. I have satisfied myself as to the correctness of his 
views respecting the existence of this acid, and the properties 
of its compounds; but T cannot regard the method he has 
adopted for its analysis as entitled to confidence. He takesa 
given quantity of hypophosphite of soda, acts upon this by 
chlorine, converts the excess of chlorine into muriatic acid, pre- 
cipitates by nitrate of silver and earthy salts, and from the com- 
parison of all these data, in which some substances of uncertain 
composition may be concerned, draws his conclusions. 
I have found that the neutral hypophosphite of barytes, when 
acted on by heat in close vessels, is converted into acid phos- 
phate of barytes, disengaging an elastic fluid, which is almost 
Vol. 52. No.248, Dec. 1518. Ff entirely 
