TRANSACTIONS OP THE SECTIONS. 45 



0« a Calorimotor for Igniting Gases in Eudiometrical Experiments, and 

 Gunpowder in Rock-blasting. By R. Hare, M.D. 



This is a galvanic instrument of two pairs, for producing ignition at 

 a distance from the apparatus : when it is an object to produce ignition 

 at a greater distance. Dr. Hare resorts to analogous apparatus of larger 

 size and consisting of four pairs. 



By means of potassium ignited by this instrument. Dr. Hare has 

 been enabled extemporaneously to evolve silicium or boron from fluo-si- 

 licic or fluo-boric acid gas. 



He has also been enabled to explode gunpowder at a great distance. 

 In one instance, twelve charges had been exploded at 150 feet from the 

 calorimotor employed. 



A projector of the name of Shaw had attempted to effect the explo- 

 sion of gunpowder by means of the Leyden jar, for the purpose of rock 

 blasting, but finding mechanical electricity too precarious, had applied 

 to Dr. Hare for means of rendering his process more certain, and this 

 had led to the following contrivance. Two iron wires of about the 

 size No. 40, and one of the finest kind were twisted together, and the 

 larger afterwards nipped, so as to leave a small portion of the fine wire 

 uncut between their nipped extremities. All the wires were secured 

 in a saw kerf in a piece of hard wood, having a small hole filled with a 

 fulminating powder, consisting of arsenic and chlorate of potash, 

 through which the fine wire passed. The powder was secured by paper 

 pasted on by means of gum arable. One termination of the twisted 

 wire was soldered to a dish of tinned iron, by which the lower end of 

 a tube of the same material was closed. The tube being then filled 

 with gunpowder was closed by a cock, through which the upper end 

 of the twisted wire was made to pass. To the outside of the tin tube 

 a strip of metal or a wire was soldered. By connecting these wires 

 with the poles of a calorimotor, ignition of the gunpowder in the tube 

 might be effected at every distance, or in any situation, and as well 

 under water as above it. 



Many accidents had happened in the ordinary mode of blasting, from 

 causes which could not be operative in the use of the means above de- 

 scribed. The principal source of danger is the liability of the gunpowder 

 to explode during the ramming of it into the perforated rock, or before 

 the workmen had time to get out of the way. 



In Dr. Hare's method, the gunpowder being inclosed in a metallic 

 tube previously to its introduction into a perforated rock, is not liable 

 to ignition from the process of ramming. 



Dr. Hare conceives that the intervention of the fulminating powder 

 would greatly accelerate the combustion, and of course increase the 

 force of the explosion. 



