the Combinations of Phosphorus. 44} 
much from each other, and from mine, are stated. I ventured 
to conclude that the phosphoric acid contained double the quan- 
tity of oxygen to that in the phosphorous acid; and that phos- 
phoric acid contained about 3-5ths of its weight of oxygen. 
M. Berzelius considers the oxygen in phosphoric acid to be 
128-17, and M. Dulong, 124°5, the phosphorus being 100. M. 
Dulong and M. Berzelius suppose the quantity of oxygen in 
phosphorous acid to be to that in phosphoric acid as 3 to 5. 
The motive which immediately induced me to resume the in- 
quiry respecting the phosphoric combinations, was M. Dulong’s 
paper. This ingenious chemist has not only endeavoured to 
establish new proportions in the known compounds of phospho- 
rus, but has likewise attempted to prove the existence of two 
new acids of phosphorus; and has denied several facts which I 
considered as sufficiently established. 
The details which I have to lay before the Society in the fol- 
lowing pages, will serve to correct and fix, I hope, with tolerable 
accuracy, the proportional number or equivalent of phosphorus, 
and at the same time will show the truth of the general series 
of proportions that I assigned to its compounds. In a case 
where my conclusions differ so materially from those of M. Ber- 
zelius and Dulong, it may be supposed that I have not adopted 
them without considerable caution ; and I have preferred my own 
results to theirs, only because they have been confirmed by mi- 
nute and repeated experiments. 
I was certain from various experiments, made both long ago 
and recently, and the results of which had been confirmed by 
Mr. Brande, that the proportion of oxygen, which M. Dulong 
assigns to phosphoric acid, is considerably smaller than that de- 
noted by the combustion of small quantities of phosphorus in 
oxygen gas. I knew that minute portions of phosphuretted hy- 
drogen were separated from phosphorus by Voltaic electricity ; ; 
and it occurred to meas possible, that water might be formed in 
the combustion of phosphorus, a and separated from the phosphoric 
acid when it entered into saline and metallic combinations. To 
ascertain if this were the case, I passed phosphorus to saturation 
through red-hot lime in a green glass tube connected with a mer- 
curio-pneumatic apparatus: the combination took place with 
vivid ignition ; but no elastic fluid was produced. A portion of 
the phosphuret of lime formed, was introduced into a trav of 
platinum, and heated in a glass retort filled with oxygen gas ; ‘the 
phosphuret of lime burnt brilliantly, and became partly converted 
into phosphate of lime; but on restoring the original tempera- 
ture of the retort, there was no appearance of vapour or of mois- 
ture. 
Having examined the phosphate of lime formed in this opera- 
tion, 
