90 
CAPTAIN NOBLE AND MR. E. A. ABEL ON EIRED GUNPOWDER. 
given; but for our present purpose it is convenient to give the proportions of the 
components, as found by analysis, in their elementary form. 
The pebble powder, then, consisted of : — 
Percentage composition. 
Composition by weight, 
grammes. 
K . . 
. . . -2886 
118-639 
C . . 
. . . -1212 
49-824 
S . .. 
. . . -1007 
41-396 
H . . 
. . . -0052 
2-138 
O . . 
. . . -3742 
153-828 
N . . 
. . . -1078 
44-315 
Ash . 
. . . -0023 
•945 
1-0000 411-085 
while the composition of the solid products of combustion was found to be : — 
K 2 C0 3 . . 
. -55220 
KCNS . . . 
•00244 
K 2 S 2 0 3 . 
. -14080 
kno 3 . . . 
•00084 
k 2 so 4 . . 
. -13200 
(NH 4 ) 2 C0 3 . 
•00067 
K 2 s . . . 
. -09700 
s 
Not estimated . 
•06058 
•01347 
Now almost any practical method of weighing the solid residue would give us 
inexact results, the weight of the vessel used for explosion being too great to allow of 
sufficient accuracy if weighed in the vessel, and the hygroscopic nature of the residue, 
as well as the difficulty of removing it, preventing its being weighed after removal. 
But we can arrive at the weight in the following manner: — We know that the whole 
of the potassium originally contained in the powder will be found in the solid residue ; 
we further know that potassium enters into the composition of potassium carbonate, 
hyposulphite, sulphate, sulphide, and sulphocyanate in the proportions respectively of 
565, 411, 448, 709, and 402 parts out of every thousand. Hence if x be the weight 
of the solid residue we have the following equation : — 
{•565 X -55220+-411 x T4080+-448X T3200 + -709 X -09700 
+ •402 X -00244 + -386 x -00084^=118-639, 
118-639 grms. being the amount of potassium originally in the powder. 
Hence x= solid products = 237-717 grms. =-5783, and by difference gaseous 
products = 173-368 grms. = -4217. 
We can now perform the inverse process, and, from the measurement of the gas 
and the gaseous analysis, arrive at the weight of the solid products. Since 1 grm. of 
pebble powder gave rise to 275-68 cub. centims. of permanent gases, 411-085 grms. will 
generate 113,797-9 cub. centims. But the analysis of the permanent gases, in this 
particular experiment, gave SH 2 -0170 volume, CO -1395, C0 2 ‘4952, CH 4 -0032, 
H -0235, N -3216 volumes, while a cubic centimetre of these gases weighs respectively 
•001523, -001254, -001971, -0000896, and -001254 grm. Hence we have as follows 
