


IMPROVED FORMS OF BOMB CALORIMETER. 207 
and for the thermometer. The covers and the thermometer 
are held in place by specially devised clamps fastened to the 
pails. ‘The current for igniting the iron wire over the sub- 
stance to be burned in the capsule (O) is conveyed by the 
rubber covered wires, of which one is connected with the valve 
screw of the bomb and the other with the insulated platinum 
wire (H) which passes through the cover. The thermometers 
used for determining the temperature are of special construc- 
tion and graduated to one-hundredth of a degree, and capable 
of being read to thousandths by use of a magnifying glass. 
Those here used were 
made by Fuess, and cali- 
brated at the Physikal- 
isch-technische Reichsan- 
staltin Berlin. A hook on 
the top bar of the stirrer 
holds a watch for time 
readings conveniently near 
the thermometer. 
ACCESSORY APPARATUS. 
Apparatus for moving 
stirrer and for igniting the 
charge for combustion.— 
The most convenient 
source of power for rais- 
ing and lowering the stir- 
rer we have found to be 
the direct or alternating 
; Fia. 5.—BOMB CALORIMETER READY FOR 
current of the city elec- A COMBUSTION. 
trical circuit with suitable 
motors. ‘The same current serves to ignite the charge. As 
yet no perfectly satisfactory substitute for these currents has 
been found. Six cells of the Edison-Lalande batteries have 
most nearly filled the requirements. In Fig. 5 a small motor 
is shown connected in series with a 16-candle power 110-volt 
lamp. ‘his style of motor is better adapted for a 55-volt cir- 
cuit, using a 55-volt lamp in place of the 110. A one-twelfth 
H. P. high resistance motor is generally used for 110 volts, as 
it is more durable. 

