72 PROVOSTAYE ON THE ACTION OF 
is effected, some pieces of burning charcoal are held near the sub- 
stance, and gas is almost immediately disengaged with rapidity. 
The operation is terminated by increasing the heat, and evolving 
more carbonic acid, until the volume of gas in the gas receiver, 
which must contain a strong solution of potash, is not sensibly 
increased. Of three attempts to estimate the nitrogen by this 
means, two have been slightly defective, in consequence of the 
column of copper not being sufficiently long. I have assured 
myself that, at least in one of these instances, traces of nitric 
oxide were present in the nitrogen. These two attempts, the 
details of which I do not communicate, have afforded 11 and 
11°2 per cent. of nitrogen. It was after these imperfect endea- 
vours, that the length of the column of copper was increased to 
twenty-two centimetres, and copper was also introduced in the 
small tube. The third experiment succeeded perfectly. The 
numbers obtained were as follow :— 
0°624 gramme gave 63°73 cubic centimetres of nitrogen gas, 
under a pressure of 0°746 metre*, and temperature of 16° cent. 
(60° Fahr.). The corrections being made, we obtain 58°08 
cubic centimetres of dry gas at 0° cent. (32° Fahr.), and under 
a pressure of 0°76 metre. Adopting 0°975 for the density of 
nitrogen, this number will afford us 11°79 per cent. of this ele- 
ment. 
The water was determined by a separate experiment; the 
tube not having been sufficiently dried in the preceding, water 
was observed to condense in the cool part of the tube previous 
to the decomposition of the substance. The whole water, how- 
ever, collected does not amount to so much as one equivalent. 
0°734 gramme of substance, decomposed in the same manner, 
gave 
Water . . . . 0-0] gramme, 
so minute a quantity as to be entirely neglected. We have then 
as the composition of this substance, 
LL eR nf | 
Pires 15) a) RS 
Geren Al) 2. P03 
100°00 
which numbers correspond very closely with the formula S O,, 
N O, + 8 O, O, the per centage composition for which is 
* The metre is equal to 39°3710 English inches. 
