446 New Experiments on some of 
nished, and not increased, by uniting with phosphoric and mu- 
riatic acids, so that the apparent absorption must have been less 
than the real one. Adding the second absorption to the first, 
and making the proper corrections, the quantity of chlorine 
uniting to four grains of phosphorus was 31:9 cubical inches ; 
barometer being 30:1 inches, and thermometer 46° Fahrenheit. 
Rather a larger proportion would be given, if the correction 
for the presence of vapour had been made for some of the other 
experiments : and the result agrees exactly with the mean de- 
duced from the absorption of oxygen in the formation of phos- 
phoric acid; for, assuming that 100 cubical inches of chlorine 
weigh 76:5 grains, then the sublimate will consist of one of 
phosphorus to nearly six of chlorine; and taking the composi- 
tion of phosphoric acid from this datum, it would consist of 100 
of phosphorus and 135 of oxygen. 
To ascertain the composition of phosphorous acid, I used a 
new method, that of converting the perchloride of phosphorus, 
or perphosphorane by phosphorus, into the chloride which 
affords phosphorous acid by the action of water. This is easily 
done by heating them together in a close retort ; and it enables 
us to determine with certainty, which opinion is correct, that 
assuming the oxygen in phosphorous acid to be three, or that 
which supposes: it to be 25, the oxygen in phosphoric acid 
being five. 
Five grains of phosphorus were converted into perchloride in 
a small retort of the capacity of six cubical inches: it was neces- 
sary toexhaust this retort twice, to remove the residual common 
air mixed with the chlorine, and some perchloride must have 
been lost during this process. A small quantity of chlorine, 
which could have been little more than sufficient to compensate 
for the loss, remained in the retort. Five grains of phosphorus 
were introduced, and the retort suffered to remain filled, prin- 
cipally with common air; heat was very slowly applied ; all the 
phosphorus, except an atom not so big as the head of a small 
pin, disappeared, and a little of the sublimate still remained, 
when the retort burst from the expansion of the vapour of the 
new chloride formed; but the chloride found on the fragments 
was pure, aud held no phosphorus in solution. 
A second experiment was made in a retort of the capacity of 
11 cubical inches. Five grains of phosphorus were converted 
into perchloride: the retort was twice completely exhausted, by 
which at least a grain and a half or two grains of perchloride 
must have been lost. Five grains of phosphorus were intro- 
duced ; alittle of the sublimate was lost by falling into the stop- 
cock of the retort; yet the conversion of the phosphorus by 
heat into the liquor was almost complete; there remained only 
a minute 
