356 



Apparatus for Rock Blasting. 



powerful* Metallic arsenic, and chlorate of potash finely powder- 

 ed and mingled, made an excellent explosive powder for this pur- 

 pose ; being more ready to explode from heat, and less so from oth- 

 er causes, than fulminating silver or mercury. Sulphur maybe used 

 in lieu of arsenic. Yet the use of these is not necessary, as the gun- 

 powder will take fire directly from the wire, at least as effectually as 

 in the usual mode. 



Description of a Galvanic Machine, for producing ingnition in Rock 



, Blasting. 



Diagram illustrating the arrangement of the plates 



l 



A 



2 



C 



I C 



4 



a 



15 



3 



This machine consists of sixteen plates of zinc, and twenty plates 

 of copper, each twelve inches by seven, arranged in four galvanic 

 pairs. The plates are supported within a box with a central parti- 

 tion of wood, A B, dividing it into two compartments. Each of 



