1870.] on Ttrrcnf Drtonnfinr/ Agents^. 81 



2)late of the kind used, is but little inferior to tliat of gun-cotton, and 

 decidedly greater tlian that of tonite, if it is employed in the frozen 

 condition. 



A series of experiments has been made with cylinders of lead 

 having a central perforation 1*3 inch in diameter extending to a 

 depth of 7 inches and leaving solid metal beneath of a thickness 

 ranging from 3*5 to 5*5 inches, according to the size of the cylinders 

 used. These furnished results of considerable interest as illustrating 

 the action of these several detonating agents. Charges of 1*25 oz. 

 of each explosive substance were used throughout the experiments, 

 and were placed at the bottoms of the holes. By the detonation of 

 the charges the cylindrical holes in the lead were enlarged into 

 cavities of a pear shape (and sometimes approaching the spherical 

 form), of various diameters ; in some instances the metal was besides 

 partially torn open in a line from the bottom of the charge-hole to 

 the circumference of the lower face of the cylinder ; and in the case 

 of some of the gun-cotton cliarges, the fissure in the metal in this 

 direction was complete, the base of the block being separated from 

 the remainder, in the form of a cone. In the first place the portions 

 of the holes above the charges were simply left open ; in the subsequent 

 experiments they were filled up to a level with the upper surface, with 

 dry, fine, loose sand, or with water. The dimensions of the cylinders 

 were increased in successive experiments until, in the case of every 

 one of the explosives used, the mass of metal was sufficiently great to 

 resist actual fracture at the base of the cylinder. Under the con- 

 ditions of these experiments, more or less considerable resistance 

 being opposed to the mechanical dispersion of the plastic explosive 

 substances, their detonation was greatly facilitated, though even then, 

 the holes in the lead blocks being left oj^en to the air, some amount 

 of the blasting gelatine evidently escaped detonation ; the widening 

 of the upper part of the charge-hole, in experiments of this nature 

 made with the gelatine, indicated that detonation was transmitted to 

 small portions dispersed in the first instance and in the act of escaping 

 from the block. In all the experiments, whether the holes were left 

 open or filled with sand or water, the effect produced ujDon the base 

 of the block by the detonation of compressed gun-cotton was con- 

 siderably more violent than with the other explosive agents, indicating 

 a sharpness of action which was only shared by the blasting gelatine 

 when used in a frozen state in one of these experiments. The dimen- 

 sions of the cavities produced by the gelatine were, at the largest part, 

 considerably greater than those j)roduced by the dynamite and nitrated 

 gun-cotton (tonite), and slightly greater than those of the gun-cotton 

 charges ; but in tlie latter, the fracture of the base of the cylinder gave 

 rise in most of the experiments to an escape of force, so that in these 

 cases the effects of the detonation could not be well compared by 

 measurements of the cavities. When the gelatine was converted by 

 freezing into a rigid mass its superiority in exj^losive force even over 

 compressed gun-cotton was well illustrated ; the base of the lead block 



Vol. IX. (No. 70.) o 



