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POPULAR SCIEXCE MONTHLY 



and wider the hole in the gun cotton the deeper and wider were 

 the holes produced in the iron j^late, until when the completely 

 perforated gun-cotton cylinder, from which at least half of the 

 weight of explosive had been removed by the boring, was fired, 

 the iron plate was found to be completely perforated. 



Advantage was taken of this action of the rapidly moving mole- 

 cules to produce some beautiful effects by interposing laces, coins, 

 leaves from the trees, and stencils wdth various devices cut in them 

 between the base of the gun cotton and the iron plate, for after 

 the detonation of the gun cotton the objects were found to be 

 reproduced upon the iron with the utmost fidelity and in their most 

 delicate parts, and the impressions were raised upon the iron as the 

 objects had been before the explosion. 



In one instance a disk of gun cotton was placed in a tin which 

 had been used in canning peas. The disk was covered with water 



so as to be completely immersed 

 in it, and a second dry disk, with 

 which to fire it, was placed upon 

 the wet one. The face of the 

 can resting in contact with the 

 iron plate was originally the top 

 of the can, through which the 

 vegetable had been introduced, 

 and it was consequently grooved 

 where the cover was soldered 

 on, and it also had an irregular 

 drop of solder over the vent 

 hole, the solder being raised, 

 therefore, above the general 

 level of the face. On firing, the can was completely volatilized 

 or comminuted as usual, but the face of the can w'as reproduced in 

 every feature and with the original values of the surface, the groove 

 being indented in tlio iron, and the solder being raised above the 

 rest of the impression. 



In another instance a disk of gun cotton three inches in diam- 

 eter was placed in a tin can five inches in diameter, and the can, 

 which had a smooth bottom, placed on the face of an iron I-beam. 

 The can was filled with w'ater so as to just cover the gun cotton, a 

 second dry gun-cotton disk was placed on the wet disk of a primer, 

 both being in constant contact with one side of the can, and the 

 system detonated. As a result the can and water disappeared and 

 the face of the beam was torn off, but on recovering the pieces and 

 matching them it was found that not only was the smooth base of 

 the gun cotton and the face of the can reproduced in the iron, but 



Maplk I>eaf KEPRonucF.i) ox Iron Plate. 



