
IMPROVED FORMS.OF BOMB CALORIMETER. 209 
easily be blown out and escape combustion. ‘The pellet press 
and mould are shown in Fig. 6. The press is so constructed 
that a pressure of 50 pounds (22% kilos), applied at the 
extremities of the screw arm gives a pressure of over Io tons 
(9,100 kilos) on the pellet pin. In practice such a pressure is 
rarely needed. 
The mould consists of three parts: a cylindrical block of | 
steel with a standard half-inch bore; a cylindrical pellet pin of 
the same size serving as piston; and a cylindrical disk which, 
like the pellet pin, fits the bore so tightly that when the finely 
powdered material is held inside the mould between the two, 
and the pressure applied to compress it into a hard cylindrical 
pellet, none can be forced in between the’ pin or disk and the 
mould. To remove the pellet the top of the pin is rapped with 
a mallet. ‘The disk falls out first and the pellet follows. The 
pellets of some substances as cane sugar are friable and easily 
shattered by the blows of the mallet. To remove these the 
mould is supported on two pieces of hard wood in the press, and 
the pin is gently forced down by turning the screw so that the 
steel disk is forced out and the pellet follows intact. 

Fia. 7.—CLAMP AND SPANNER. 
Clamp and spanner.—Considerable difficulty has been found 
in holding the bomb securely while the cover is being screwed 
down. ‘I'he external surface of the bomb cylinder is smooth 
and polished and gives very little opportunity for a tight grip. 
The form of clamp or vise shown in Fig. 7 was devised for the 
purpose and has proven very efficient. 
15 

