SHORT NOTES ON PROFESSIONAL SUBJECTS. 
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2. A detonating fuze containing 10 grains of percussion cap mixture was 
inserted into the perforation of a one-ounce disc of gun-cotton and fired. 
No explosion occurred; the gun-cotton merely burned away. 
3. A detonating fuze containing 10 grains of fulminate of mercury was fired on 
a hank of gun-cotton thread. No explosion—gun-cotton went off in 
sudden flame. 
4. A fuze charged with 5 grains of pure fulminate of mercury was inserted into 
the hole of a disc of compressed gun-cotton. Its explosion caused the 
gun-cotton to detonate violently, with very destructive effect. 
5. A fuze charged with only 2 grains of fulminate of mercury was inserted, 
through the cork, into a bottle containing f ounce of pure nitro-glycerine, 
which was placed on a thick plank of timber. A sharp explosion followed 
the ignition of the detonator, and a hole was blown in the timber imme¬ 
diately under where the bottle rested. 
6. A similar bottle of nitro-glycerine, fitted as above, was placed on a £lb. disc 
of gun-cotton. The nitro-glycerine exploded, but simply scattered the 
gun-cotton, portions of which were inflamed. 
7. An ounce of gun-cotton fitted with a 5 grain mercury detonator, was fired 
alongside a f ounce bottle of nitro-glycerine. The latter was detonated by 
the explosion of the gun-cotton. 
The above experiments demonstrate that an explosive mixture, such as per¬ 
cussion cap composition, will not detonate gun-cotton even if used in 
considerable quantities, whereas a charge of 3 grains of the same 
composition is sufficient to detonate nitro-glycerine. 
They also showed that it is necessary for the gun-cotton to be in a compressed 
condition, and that a particular kind of detonation must be produced, in 
order to ensure the detonation of the gun-cotton. 
The following experiments illustrate the force of gun-cotton as compared 
with gunpowder, when the former is ignited by a proper fulminating fuze : — 
8. A cylindrical paper cartridge, 9 inches long by 1 inch in diameter, was filled 
with ordinary gunpowder (5 oz.), and inserted in a hole bored in an upright 
timber balk 12 inches square. The powder fired with a puff, slightly 
splitting the wood. 
9. A similar cartridge filled with gun-cotton (4 oz.), was inserted in a similar 
balk. The gun-cotton detonated with a loud explosion, and the balk was 
cut off level with the ground. 
10. A stockade was formed of four wooden balks, each 12 inches square, let 
into the ground about 2 feet 6 inches, and well strutted behind. 
A 1 lb. disc of gun-cotton was placed in the centre of each balk, the intervals 
being filled with i lb. discs (10); thus all the discs were touching. 
One of the extreme discs was fired by a detonating fuze, when the whole 
exploded with great violence, cutting down the stockade level with the 
ground, and hurling the pieces all round. 
11. A 1 lb. disc of gun-cotton was detonated on a block of stone 2 ft. x 3 ft. 
X 1 ft. 3 ins. The stone was blown into powder; 
12. A 9 inch cast-iron cylinder of 250 lbs. weight, was drilled with a 1£ inch 
hole in the centre, and a charge of 4 J ounces of gun-cotton inserted, the 
hole being left quite open at the top. The cylinder was placed in a pit 
about 2 feet deep in the ground, and the charge detonated. The cylinder 
was blown into many pieces, which were subsequently found embedded in 
the sides of the pit. The base of the cylinder was driven into the ground 
to some depth. 
