150 



OALORIMETRIC APPARATUS. 



tion of heat, and contains more energy than the oxygen and 

 nitrogen which constitute it. This circumstance is all-important, 



for it explains the combustion 

 power of the oxygenated com- 

 pounds of nitrogen. 



5. This being established, we 

 proceed to describe the apparatus 

 employed, and to give some types 

 of experiments in order to charac- 

 terise the method. As for the forms 

 of the apparatus, they belong to 

 two models the ellipsoidal and 

 the semi-cylindrical bomb, the 

 method of closing these two models 

 being slightly different. But the 

 introduction of the gases, their 

 extraction, the ignition, and the 

 measurement of the heat liberated 

 are always effected in the same 

 manner. 



Fig. 21 represents the calori- 

 rnetric bomb employed for the 

 author's first measurements. Its 

 capacity is 218 cms., and its value 

 in water 51 grms. 



It is formed of a receiver, B'B', 

 and of a cover, BB (Fig. 22), held 

 together by a screw joint provided 

 with lugs, 00, both of steel plate, 

 2*5 mms. in thickness. They were 

 electro-plated internally with a very thick layer of gold, weighing 

 about 22 grms., which resisted all the explosions. At first the 



bomb was plated internally with 

 platinum, but platinum thus de- 

 posited does not stand prolonged 

 use. After a certain number of 

 observations, the platinum is raised, 

 I or eliminated, during cleaning, and 

 - the exposed iron becomes oxidised 

 during the explosions, especially 

 when water is formed. Platinum 

 electro-plating was therefore com- 

 pletely abandoned. The weight 

 of the gold fixed on the interior 

 should be determined by special 

 weighings, so as to be able to find the value of it in water, 

 simultaneously with that of the steel. The exterior surface of 

 the bomb was also nickel-plated, to render it less oxidisable. 



Fig. 21. Calometric bomb 

 (section). 



Fig. 22. Cover. 



