An apparatus, devised by Horsley, was used, which consisted of an iron stand with a ring support holding a hemispherical iron vessel, in which paraffin or tin was put. Above this was another movable support, from which a thermometer was suspended and so adjusted that its bulb was immersed in molten material in the iron vessel. A thin copper cartridge case, 5/8 in. in diameter and 1-5/16 in. long, was suspended over the bath by means of a triangle, so that the end of the case was 1 in. below the surface of the liquid. On beginning the experiment the material in the bath was heated to just above the melting point, the thermometer was inserted in it, and a minute quantity of the explosive was placed in the bottom of the cartridge case. The temperature marked by the thermometer was noted as the initial temperature, the cartridge case containing the explosive was inserted in the bath, and the temperature quickly raised until the explosive flashed off or exploded, when the temperature marked by the thermometer was again noted as the firing point. The tables given show the results of about six experiments with each explosive. The initial temperatures range from 65° to 280° C. in some cases, but as the firing points remained fairly constant, only the extremes of the latter are quoted in the following table:

Description of Explosive.Firing Point in ° C.
Compressed military gun-cotton.186 - 201
Air-dried military gun-cotton.179 - 186
"186 - 189
"137 - 139
"154 - 161
Gun-cotton dried at 65° C.136 - 141
Air-dried collodion gun-cotton.186 - 191
"197 - 199
"193 - 195
Air-dried gun-cotton.192 - 197
"194 - 199
Hydro-nitrocellulose.201 - 213
Nitroglycerin.203 - 205
Kieselghur dynamite. No. 1.197 - 200
Explosive gelatin.203 - 209
Explosive gelatin, camphorated.174 - 182
Mercury fulminate.175 - 181
Gunpowder.278 - 287
Hill's picric powder.273 - 283
"273 - 290
Forcite, No. 1.184 - 200
Atlas powder, 75 per cent.175 - 185
Emmensite, No. 1.167 - 184
Emmensite, No. 2.165 - 177
Emmensite, No. 5.205 - 217

- C.E. Munroe, J. Amer. Chem. Soc.