THE ARTIFICIAL PRODUCTION OF DIAMOND. 
73 
0'303-iiich diameter had been drilled to a depth somewhat greater than the length 
of the bullet, and in alignment with the bore of the gun ; the trigger was pulled by 
a string from without. Cylindrical bullets of steel with a copper driving band were 
used, shorter than the service bullet, and about one-half of the weight, some with 
cupped noses to entrain material, some with coned noses to match the l)ottom of 
the hole in the block. The velocity witli 90 per cent, excess charge was estimated to 
be about 5000 ft./secs. 
The substance to be compressed was placed either at the bottom of the hole when 
the coned-nose bullet was used, or over the mouth of the hole when the cupped-nose 
^o-sos'dia. 
bullets were used. Some of the bullets were of mild steel, but those with cupped 
noses were of tool steel. 
The substances placed in the hole are given in the Appendix, and included graphite, 
sugar carbon, bisulphide of carbon, oils, &c., graphite and sodium nitrate, graphite 
and fulminate of mercury, finely divided iron and fine carborundum, olivine and 
graphite. After each shot (fig. 7) the bullet and surrounding steel were drilled out, 
and the chips and entrained matter analysed. 
Several experiments were also made with a bridge of arc-light carbon just over the 
hole, raised to the limit of incandescence by an electric current, and the shot fired 
through into the hole at the moment the carbon commenced to vaporize, as observed 
in a mirror from without. Also an arc between two carbons was arranged just over 
