On the properties and uses of Gun-cotton. 1 1 1 



nitrogen, nitrogen, cyanogen, and aqueous vapour. There was un- 

 doubtedly an acid product formed, i. e. nitrous acid, from the 

 deutoxide of nitrogen. This was proved by placing in a bell-jar, 

 having some cotton at the bottom, a long strip of litmus paper, and 

 another strip of paper soaked in a solution of iodide of potassium. 

 On discharging the gun-cotton by a heated wire, the litmus paper 

 was reddened, and, on the other strip of paper, iodine was set free. 

 Beside this, it was made evident that the bell-glass contained ruddy 

 fumes indicative of the production of nitrous acid. The fact was also 

 subsequently illustrated by discharging a small pistol loaded with gun- 

 cotton at a sheet of litmus paper wetted and placed on a board : the 

 vapour in the discharge reddened the paper. On firing an equal weight 

 of gunpowder, it was proved that an alkali (sulphuret of potassium) 

 was evolved. It was stated that, weight for weight, the explosive 

 force of gun-cotton was as six to one compared with gunpowder. 



Even when the cotton possessed no acidity whatever, an acid 

 resulted from its combustion. The Professor exploded on a sheet of 

 litmus paper some of the cotton prepared by Schonbein himself, and 

 also an excellent specimen prepared by Mr. Bell, of Oxford Street.* 

 In both cases a wide red stain was left after the explosion. 



Gun-cotton is remarkably hygrometric, and absorbs water with 

 great rapidity. This interferes with many of its properties, and it 

 requires to be thoroughly dried before use. If a portion well dried 

 be balanced in a scale, it will be found to increase rapidly in weight 

 by a very short exposure. It also possesses another curious property, 

 namely, that it is remarkably electrical. The slightest friction deve- 

 lopes in it a large quantity of negative electricity. In order that this 

 property should be manifested, the cotton should be previously well 

 warmed, to deprive it of hygrometric water. A thin strip dried was 

 drawn between the fingers, and then placed over a gold-leaf electro- 

 scope ; the leaves diverged to a great degree in an instant. The 

 Professor remarked, — what all who have prepared this substance 



* This cotton, which appears to be even superior to that of Schonbein, is 

 prepared with the two acids in the same proportions poured over the cotton in 

 a perforated funnel for about five minutes. It is well washed in water, then 

 in a weak solution of ammonia, and afterwards dipped in a very weak solution 

 of nitrate of strontia, which causes it to burn with a bright red flame. The 

 suddenness of explosion in this cotton is perfectly astonishing. 



