458 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ber of mines, and the results of tests made of it, although not 

 unfavorable, place its explosive force, which, however, does 

 not seem to be uniform, at at least three times that of an 

 equal weight of blasting-powder, instead of at five times, as 

 claimed at first ; the price has therefore been fixed by the 

 manufacturer on the basis of the former, at something less 

 than that of an equivalent quantity of powder. Great safety 

 is stated as one of the advantages of its use, as it is said 

 not to be exploded by contact with naked fire, and with diffi- 

 culty by friction or percussion, while it can be used with a 

 fuse in blasting. It is also said that but little, and that harm- 

 less gas, is left after explosion. In the Polytechnisches-Cen- 

 tralblatt, however, an account is given of an explosion and the 

 destruction of the building in which cartridges of it were pre- 

 pared by women, by stamping it into cases, although, accord- 

 ing to tests made under governmental supervision, the occu- 

 pation had been pronounced perfectly safe. The combustion 

 of the cartridges, when first noticed, was so slow that twenty- 

 two out of twenty-three persons employed escaped unhurt 

 before the explosion occurred. 6 (7, September 23, 1875, 375, 

 and 13 C, July 1, 1875, 851. 



INFLUENCE OF HEAT ON THE EXPLOSIVENESS OF NITEO- 



GLYCERINE. 



Sergius Kern, of St. Petersburg, has been studying the ef- 

 fect of heat upon nitro-glycerine. The sample examined had 

 a specific gravity of 1.6, and solidified at 4 Centigrade to a 

 crystalline mass. At 187 it entered into ebullition, w^ith 

 separation of orange -colored vapors; at 220 it exploded 

 strongly, at 262 more violently, and at 294 the explosion 

 was very feeble, being accompanied by a yellowish flame. In 

 other Avords, the explosive properties of the substance nearly 

 vanished at a high temperature. 1 .4, XXXIII. , 153. 



EXPEEIl^IENTS W^TH PRISMATIC GUNPOWDER. 



In the course of some experiments made by the permanent 

 Austrian Committee, it is noted that the Austrian prismatic 

 powder has a smaller kernel and a less density than that 

 ordinarily employed in Prussia for six-inch cannon ; and the 

 result of the experiments made w^ith this powder shows that 

 the maximum pressure exerted by it upon the common ball 



