148 STORRS AGRICULTURAL EXPERIMENT STATION. 
current,) and the arrangement above referred to for moving the 
stirrer. The manipulation requires the same skill that is demanded 
for accurate laboratory determinations in general and no more. 
The actual process is briefly as follows: ‘The substance to be 
burned is, when convenient, pressed into a cake, and, after 
weighing, put in the small platinum capsule; the latter is then 
placed in the ring support under the small iron wire connecting 
the two platinum wires H and I. The bomb cover, which holds 
these wires and with them the capsule, is then put on the 
cylinder, the collar is screwed on, the oxygen 1s introduced until 
the pressure indicates at least 20 atmospheres. The bomb is 
then put in the calorimeter cylinder inside the larger cylinders; 
the covers, stirrer, thermometer, and connecting wires H and I are 
properly arranged; and the apparatus is allowed to stand, generally 
for not more than three minutes, until the temperature of the water, 
which at the outset is two degrees or a little more below that of the’ 
room, begins to rise. Six initial readings are then taken at inter- 
vals of one minute, these generally show a rise of from two to four 
hundredths of a degree. At the moment of the sixth reading, 
which is taken for the initial temperature of water and apparatus, 
the current is turned on, the wire is ignited at the same moment 
and falls, igniting the substance. The combustion takes place 
quickly but quietly, and the temperature forthwith begins to rise. 
The thermometer is read for five minutes at intervals of one 
minute and again after ten minutes more. The first of the initial 
readings, the one at the moment of turning on the current, the 
five which follow and the last one are used in a formula* for 
computing the correction for the influence of the temperature of 
the air in the room upon the change in temperature of water and 
apparatus during the combustion. The result shows the actual rise 
of temperature of water and apparatus (bomb, calorimeter cylinder, 
stirrer and thermometer) due to the combustion. The next steps 
are to find the number of calories of heat which correspond to the 
rise of temperature of water and apparatus and then the calories of 
heat actually developed by the combustion of the substance. For 
the first it is necessary to know the thermal water equivalent of 
the apparatus. This has to be determined for each apparatus 
and under the circumstances in which it is to be used. The 
methods here followed are essentially those described by Stoh- 
mann, Kleber and Langbein.t The quantity of water thus 

* The formula here used is essentiaily the same as developed by Stohmann, Kleber and 
Langbein, Jour. f. prac. Chem., 147, 1889, 517-523. + Loc. cit. 524-536. 
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