the Combinations of Phosphorus. 447 
a minute fragment. In this experiment, however, the liquor 
held phosphorus in solution. When this phosphorus was pre- 
cipitated by water, and obtained with the fragment by sublima- 
tion in a small glass tube, it did not equal 7-10ths of a grain, 
and was no more than could be expected from the loss of the 
sublimate. 
These two experiments prove distinctly that the oxygen in 
phosphorous acid is half that in phosphoric acid; for if the 
proportion had been that which M. Dulong and M. Berzelius 
indicate, 1-67 grains of phosphorus, at least, ought to have 
remained after the action of the sublimate. 
A coilateral experiment was made. 32:7 grains of the fluid 
chloride, made by passing phosphorus through corrosive subli- 
mate in great excess, were acted on by water, and precipitated 
by nitrate of silver; the precipitate was immediately separated 
fromthe fluid, after it had been greatly diluted with distilled 
water. Distilled water was then repeatedly passed through it, 
and it was dried and fused, when it weighed 98-4 grains ; which, 
allowing 24-5 per cent. of chlorine in horn silver, would give 
the composition of the fluid chloride as 24-108 of chlorine, and 
8:592 of phosphorus. 
The comparative quantity of precipitate in this experiment 
was so much less than I had found in « former experiment, that, 
notwithstanding the care with which the process had been con- 
ducted, I resolved to make some more experiments of the same 
kind. In the first, in which the decomposition by water was 
made in a small bottle, from which no vapour could escape, and 
in which I superintended the weighing and drying of the horn 
silver formed, with the greatest care, 18:4 of the liquid chlo- 
ride afforded only 54:5 of chloride of silver, which agrees as 
nearly as could be expected with the former experiment. In two 
other experiments, made with equal care, and in which the 
liquid was poured into a solution of nitrate of silver, six grains 
gave 17:1 of horn silver, and 29°4 gave 89°9 of fused horn 
silver. 
In examining minutely the circumstances of the action of the 
liquid chloride, or solutions containing phosphorous and muria- 
tic acids, or nitrate of silver, I found no difficulty in explaining 
the cause of the error in the former experiments. Phosphorous 
acid acts upon nitrate of silver, and more rapidly in proportion 
to its concentration, and gradually produces a copious precipi- 
‘tate from it; so that if there be an excess of nitrate of silver, 
and the precipitate be not immediately separated from the solu- 
tion, there is always a considerable increase of weight, M. 
Dulong, and M. Berzelius, whose experiments agree with my 
former ones, may have been misled by a precipitation from the 
nitrate 
