(a) Combustible base.
(b) Explosive base.
The explosives’ bases in (b), as above, may be of the nitro-substitution class, or the nitric-derivative class.
In choosing the dopes for inert bases of dynamite where wood pulp or sawdust is employed, it should be of some porous wood such as spruce or basswood. Woods differ considerably in the amount of nitro-glycerine they will absorb, ranging from 60% to 85%. Before introducing the nitro-glycerine they should be thoroughly dried. Good dynamite should not feel greasy. There should be no trace of free nitro-glycerine inside the wrapper of the cartridge. Slowly heated dynamite explodes at a temperature of 356 deg. F. If rapidly heated, it explodes at 446 deg. F. These temperatures apply only to Kieselghur dynamite. The American dynamites containing wood pulp and nitrates will explode with somewhat lower temperatures. Like nitro-glycerine it is most sensitive to shock and friction just above the freezing point. According to the dope used, it freezes at from 42 deg. F. to 46 deg. F. It is nearly, but not quite, insensitive to shock or friction when frozen. (See page 88, Manual of Field Engineering.)
Monobel. Monobel consists of:
| Nitro-Glycerine | 7½% | to | 9½% |
| Nitrate of Amm. | 66 % | to | 70 % |
| Wood meal | 7 % | to | 9 % |
| Chloride of Sodium | 14 % | to | 16 % |
| Rem. Moisture | ½% | to | 2 % |
Fulminates. These are the most powerful and dangerous explosives in common use. They consist for the most part of metallic salts of fulminic and amic acids. The commonest fulminate, known as mercury fulminate, is formed by dissolving mercury in nitric acid, to which solution when cool is added 110 parts of alcohol. Water is then added, causing a grey fulminate to precipitate. This is carefully washed and air-dried. The operation is attended with great danger. The color of fulminate varies from a white to dirty grey. Its specific gravity is 4.42 deg. F. It has a sweetish taste and is highly poisonous. It is extremely sensitive to heat and shock of every kind. Its firing point when slowly heated is 306.5 deg. F., and when rapidly heated 368.6 deg. F. When wet it is less sensitive, but not secure against explosion. The slightest friction will provoke its explosion. It may be destroyed safely by treating it with alkaline sulphides.
Fulminates of other metals are capable of being made, such as fulminates of silver, gold, platinum, zinc and copper, but these are more violently exploded and less stable. The only one which has come into any use being a silver compound. Mercury fulminate is the explosive used in the manufacture of detonators. (See page 89, Manual of Field Engineering, 1911.)
Detonators and Fuses. (See pages 89, 90 and 91, Manual of Field Engineering, 1911.)