386 
MINUTES OF PROCEEDINGS OF 
The resistance of the explosion vessels must be so chosen that the gas in 
the mortar, after explosion, has an excess of pressure of half an atmosphere, 
in order that it may subsequently be transferred to the measuring-vessels. 
The explosion-vessels which I used were made according to the directions 
of the late Lieut.-Colonel Ebner, and consisted of hollow cast-iron cylinders 
closed at one end, while at the other was a nut through which the 
arrangement for a galvanic explosion passes. Eor this purpose the nut is 
provided with an excavation in which is a thin platinum wire fastened on the 
one hand to the insulated copper wire, and on the other to the copper wire 
which passes directly through the nut. Outside the cover the wires are 
bent into knots, which, as previously mentioned, serve to support the 
cylinders and to complete the voltaic circuit. 
The weight of the gun cotton whose gases shall fill the exhausted mortar 
of 5216 cubic centims. contents so that there shall be the tension above 
mentioned, I have empirically determined, and find that it is 10 grms. The 
fact that 10 grms. of cotton somewhat compressed occupy a space of 10‘5 
centimetres in length and 2 centimetres in diameter, determined the internal 
dimensions of the cylinder. The thickness of the sides of the cylinder was 
also obtained from an empirical experiment, which showed that with a 
thickness of 8 millims. the cylinder just exploded with production of 
flame, and that thus, in accordance with the condition stated, the gun cotton 
burns away the moment the cylinder burst. 1 must here mention a peculiar 
circumstance which attracted my attention in determining the thickness of 
the side of the cylinder, and which serves to characterize gun cotton. 
Tor the above investigation I successively filled with gun cotton cylinders 
4, 6, and 8 millims. thick in the side and exploded them in a hole. Although 
the cylinders of 4 and 6 millims. in thickness contained comparatively a 
larger charge, the pieces produced were considerably larger than those of the 
cylinder 8 millims. in thickness. The former were often only split length¬ 
wise ; their cover and bottom remained unchanged, while the pieces of the 
cylinder of 8 millims. in thickness were scarcely larger than hazel-nuts. 
The above bursting vessels might also probably be constructed oC glass. 
Yery strong thick glass tubes are taken, and at each end corks cemented in, 
one of which has been provided with a galvanic conduction and the small 
platinum wire. The length of the vessels and the thickness of their sides 
could then be regulated by the quantity of gas and the desired resistance. 
The qualitative analysis of the products of the combustion of gun cotton 
under the circumstances described gave carbonic oxide, carbonic acid, 
nitrogen, marsh-gas, and a trace of a sulphurous gas (probably a bisulphide 
of carbon compound), which, from its small quantity, escaped analysis and^ 
could only be detected by the smell. This probably arises from a small trace 
of sulphuric acid adhering to the gun cotton, which either was not removed 
in washing, or by subsequent treatment with potash remained as sulphate. 
The quantitative gas analysis was made according to the following 
plan :— 
Absorption Analysis . 
Vol. at o° 
Volume, 
Pressure. Temp. and 1 metre. 
0-6242 19-1 
0-6048 20-2 
Original volume. 114-78 
After absorbing CO 2 ... 84-88 
66-94 
47-81. 
