Application of Galvanic Ignition in Rock Blasting. 139 
Arr. XVIL—On the Application of Galvanic Ignition in Rock 
Blasting ; by Rosert Hare, M. D., Prof. of Chemistry in the 
University of Pennsylvania, &c. &c. &c. 
I wave ascertained that the process for blasting rocks may be ren- 
dered safer than the firing of a fowling piece, by a new application 
of galvanism. I was led to make this improvement in consequence 
of an application by a patentee (Mr. Moses Shaw,) for assistance in 
perfecting his patented mode of blasting rocks by an electrical dis- 
charge from a Leyden Jar. 
In a letter dated June Ist, 1831, he says, “I have been engaged 
in blasting rocks by means of a fulminating powder introduced into 
several cavities, and iguited in all of them simultaneously, by a spark 
from an electrical machine, by which means masses of a much lar- 
ger size, and of a much more suitable shape, for any object in view, 
may be procured, than by the old plan. I have, however, to lament 
my inability to succeed in this method of blasting during a great part 
of the year, when, in consequence of the unfavorable state of the 
Weather, the ignition cannot be effected by electricity in any mode 
Which I have devised, or which has been suggested by others, al- 
though I have consulted all the best informed professors to whom I 
have had access.” 
It occured to me as soon as this statement was made by Mr. Shaw, 
that the ignition of gunpowder, for the purposes he had in view, might 
be effected by a galvanic discharge from a deflagrator, or calorimotor, 
in amode which I have long used in my eudiometrical experiments 
t0 ignite explosive gaseous mixtures. ‘This process is free from the 
meertainty which is always more or less attendant upon the employ- 
ment of mechanical electricity for similar purposes. 
The expectation thus arising has since been fully verified. I have 
‘suited as many as twelve charges of gunpowder at. the distance of 
— hundred and thirty feet from the galvanic machine employed. 
This distance is much greater than is necessary to the safety of the 
°perator, as the deflagrator may be shielded so as not to be injured 
'Y he explosion, and by means of levers and pulleys, itmay be made 
a any distance which may be preferable. There are no limits 
: te number of charges which may be thus ignited, excepting those 
ssigned by economy, to the size of the apparatus employed. 
