CRANE. | Developing Mineral Properties. 205 
vice versa. Kach miner must, however, determine for himself 
the charge to be employed, which is governed by the kind 
and character of rock, position and size of hole, etc. 
No firing tubes or barrels are used, as most of the blasting 
is done above the water level in so-called dry holes. 
Giant No. 2 is the powder generally employed, although 
forcite, a seventy-five per cent. powder, is being introduced. 
Giant No. 2, when used in water, is somewhat difficult to 
place, as the base or dope with which the nitroglycerine is 
mixed is light and tends to float. Dynamite gelatine is more 
readily handled and remains where it is put, as its specific 
eravity is greater than that of water, and it also holds to- 
gether well. It also tends to fill the cracks and crevices 
which may intersect the hole, and therefore prevents loss of ' 
the explosive force of the charge by its expanding in empty 
cracks. Care should, however, be taken to prevent an actual 
loss by such action, which would result from leaving the 
charge in place too long. Gelatine does not seem to generate 
as much noxious gas as does giant No. 2. 
The composition of these powders is as follows : 
Dynamite 
Giant No. 2. gelatine. Forcite. 
Saltpeter.. 2. A RIO emma battery CEN Me (ASU Ss alas Se aR ha irae 10% 
Sawausteneen: DAL es MLAs Bee a dee LIENS Ree a ee en meee 8 
INitroslycerinem40 meen DSR as persian Vda chat ee 75 
Guncotton..... QU eae Ok h te ZOU SEL A ENN oe Aa 7 
Giant No. 2 is used mainly for drifting and stoping, while 
dynamite gelatine is used for shafting. This is not a general 
rule, however, and there is no special reason except from the 
standpoint of strength and quickness why one should be used 
for one kind of work in preference to the other. 
After the ore has been loosened, large boulders which are 
exceedingly difficult to break up often remain. These bould- 
ers may be reduced by placing a fraction of a stick or a stick 
of dynamite upon them and covering the same with dirt or 
sand. When fired, the rock will be fractured, if not wholly 
broken, and the remaining portions can readily be reduced 
by sledge. This method of proceeding is known as ‘‘bull- 
dozing.”’ 
