L. MECHANICS AND ENGINEEEING. 535 



sopliical Society in 1871. On all his ascensions in 1871 and 

 subsequently he has freely invited competent meteorological 

 observers to accompany him, his own time being required for 

 the management of the aerial ship. Notwithstanding the 

 losses during the great fire in Boston, Professor King has built, 

 and very successfully used, a large balloon, designed specially 

 for carrying delicate meteorological instruments. It would 

 redound greatly to the credit of New York City could there 

 be established a stationary balloon in the Central Park, as is 

 described in Glaisher's Travels in the ^^V, that could be used 

 not only for popular amusement, but for meteorological ob- 

 servations, in charge of the director of the Meteorological 

 Observatory. 



EXPLOSIVE PAPER CARTRIDGES. 



Paper prepared in the following way explodes without 

 foulness and only on contact with fire, and is said to be 30 

 per cent, cheaper than gunpowder : Add together 79 parts of 

 water, 9 of chlorate of potash, 4^- of nitrate of potash, 3$ of 

 yellow prussiate of potash, 3^ of finely pulverized charcoal, 

 -jy of a part of starch, and ^l^ of a part of chromate of 

 130tash ; stir well, and boil for an hour. Soak paper cuttings 

 in this liquid, and dry them and make into cartridges, in tubes 

 of proper size, formed from sheets of paper saturated with 

 the liquid, and dried at 167. Protect the cartridges from 

 moisture by a solution of xyloidin in acetic acid. 34 (7, 1873, 

 IX., 92. 



ACTION OF DYNAMITE. 



A series of experiments, by MM. Roux and Serrin, recently 

 conducted for the French government, upon the eff*ects of dy- 

 namite, have led them to conclude that this substance, acci- 

 dentally inflamed (as when in the midst of a fire) will not det- 

 onate, but that it may produce an explosion of the second 

 order, similiar to that of gunpowder. The maximum intensity 

 of the explosion, obtained when the sides of the case present 

 great resistance, would be such that one of nitro-glycerine 

 represents two of powder. They state, also, that it is only 

 by a percussion of sufiicient intensity that detonation or ex- 

 plosion of the first order can be produced. Dynamite is more 

 powerful, in proportion, than nitro-glycerine, as it is more 



