MECHANICS AND USEFUL ARTS. 97 



and the miners were asphyxiated by the cyanogen given off. 

 Editor. 



Dualin is a brownish-yellow powder, similar in appearance to 

 Virginia tobacco. In the open air it burns without an explosion, 

 and in a confined space it acts like gunpowder. 



It is proof against shocks, it does not decompose, or bake to- 

 gether, can be readily put into cartridges, and can be used as well 

 in warm as in cold, in dry as in wet, places. Its strength is 4 to 

 10 times greater than the common powder, and greater than that 

 of dynamite. 



Dualin consists of cellulose, nitro-cellulose, nitro-stdrJce nitro- 

 mannit and nitro-glyceriue, mixed in different proportions accord- 

 ing to required strength. 



We believe that dualin, with its present quality and with its 

 present price, has every prospect of being useful in mining opera- 

 tions, especially in coal-mining, when with its great, but yet not 

 too quickly, working power, it can rival powder. Bergeist. 



In the " Centralblatt," of July, can be found a long account of 

 this new explosive, taken from the "Deutsche Industrie Zeitung*" 

 Editor. 



COMPARATIVE EFFECTS OF GUNPOWDER AND GUN-COTTON. 



A number of experiments have been recently carried out by the 

 officers of the Royal Engineers at Chatham to test the comparative 

 effects of gunpowder and gun-cotton in various operations. The 

 experiments were all made under the direction of Colonel W. O. 

 Lenox, C.B., Y.C., Instructor in Field Fortifications at the school 

 of Military Engineering, assisted by a number of other officers. 

 The experiments were attended by a large muster of officers of 

 the garrison, besides those of the engineering corps, and also by 

 Major-General J. L. Brownrigg, C.B., the commandant of the 

 garrison; Colonel W. Pray, Colonel Graham, C.B., Y.C., Colonel 

 Fiser, Colonel Lovell, commanding Royal Engineers ; Colonel the 

 Hon. H. F. Keare, Deputy Adjutant-GeneralRoyalEngineers ; Colo- 

 nel Clarke, etc. Mr. F. A. Abel, chemist to the War Department, 

 was also present, and assisted in some of the experiments with gun- 

 cotton. The experiments commenced with explosions of gun- 

 powder and gun-cotton directed against a double stockade of 

 balks of timber 14 inches square, 3 feet 6 inches apart, and sunk 3 

 feet in the earth, each line braced together by strong cross-pieces. 

 A charge of 200 pounds of gunpowder, in bags merely laid at the 

 foot of "the stockade, untamped, was first exploded. It forced a 

 large gap in the front stockade, but, though partially shattered, 

 the second row of timber would have presented a formidable ob- 

 stacle to an attacking party if defended by a few resolute men. 

 Portions of the timber were hurled through the air to some dis- 

 tance. A charge of 80 pounds of gun-cotton was next laid in 

 bags at the foot of the stockade, some distance from the former 

 explosion. This also was untamped. It was fired by a detonat- 

 ing fuse. There was a terrific explosion, and an almost perfectly 



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