DETAILS AND RESULTS OF EXPERIMENT. 157 



introduced into a platinum calorimeter of a capacity equal to 

 1 litre. Owing to the displacement produced by the bomb 

 550 cub. cms. of water sufficed to fill the calorimeter and 

 cover the bomb, with the exception of the screw-cock. The 

 thermometer, which served at the same time for stirrer, was 

 put in place. The value in water of the calorimeter, the 

 thermometer, and of the bomb amounted to 770-4 grms. 



The whole was left at rest for some time, in order to allow 

 the equilibrium of temperatures to become established. This 

 accomplished, the following is the course of the thermometer : 



At the outset 13-295 



After 1 minute 13'295 



2 minutes 13-295 



3 13-295 



4 13-295 



5 13-295 



The explosion is then caused by passing a single spark, 

 supplied by a very small induction coil and a bichromate cell. 

 The noise of this explosion is faint, but appreciable with ethane ; 

 this gas, and diallyl, have produced the greatest noise. Often, 

 in this kind of experiments, the noise of explosion is not even 

 heard, and its existence only known by the heating of the water 

 in the calorimeter. 



The following is the continuation of this experiment : 



After 6 minutes (from the outset) 14-740 



7 14-745 



8 14-735 



9 14-725 



10 14-715 



11 14-705 



12 ... 14-695 



The readings are suspended. 



It will be noticed how short the combustion is, and how 

 sharply defined are the phases of the calorimetric measurements. 

 This done, the carbonic acid is extracted from the bomb with 

 the aid of the mercury pump, it is dried by passing it through 

 a curved tube of concentrated sulphuric acid, and a U tube 

 filled with pumice-stone and sulphuric acid, then it is slowly 

 passed through a Liebig tube with liquid potash, followed by a 

 small U tube with solid potash. 



The extraction being carried out, and the vacuum established 

 down to a few millimetres of mercury, air (freed from carbonic 

 acid) is allowed to enter the bomb, then this air is extracted by 

 the pump and passed in its turn through the potash. This 

 operation is thrice repeated in order to extract the last traces of 

 carbonic acid formed by the combustion. The extraction lasts 

 altogether about a quarter of an hour. When it is accomplished, 

 the Liebig tube joined to the U tube is weighed, the increase of 



