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LIX. On the Heat disengaged during the Combination of 

 Bodies laith Oxygen and Chlorine. By Thomas Andrews, 

 M.D., M.R.I. A., Vice-President of Qtieen's College, Belfast. 

 [Continued from p. 339.] 

 § III. Combinations of Chlorine. 



MOST of the experiments to be described in this section 

 were performed with dry chlorine gas. The combining 

 substance, inckided in a hermetically sealed and very fragile 

 glass ball, was first introduced into the glass vessel destined to 

 contain the gas. The latter was then filled by displacement with 

 pure and tiry chlorine, and was afterwards closed by a dry 

 cork, which was traversed by a small glass tube terminating ex- 

 ternally in a capillary point. Alter the chlorine had attained 

 the temperature of the external air, the capillary orifice was 

 hermetically sealed. During this period the surface of the 

 cork was attached by the chlorine ; but careful experiments 

 proved that the amount of gas afterwards absorbed by the 

 cork was quite insignificant, at least during the length of time 

 occupied by the experiment. 



The glass vessel thus prepared was introduced into another 

 of copper, which served as a calorimeter, and was similar to 

 that employed in the experiments on the combination of the 

 gases, but of smaller size. The calorimeter was suspended, 

 as before, in a cylindrical vessel of tin plate. The tempera- 

 ture of the water in the calorimeter was taken before intro- 

 ducing the apparatus into the rotating cylinder. The whole 

 apparatus was then quickly shaken in order to rupture the 

 glass ball, and immediately placed in the rotating cylinder, in 

 which it was agitated for five minutes and a half. After the 

 final temperature had been observed, the agitation was re- 

 j)eated for one minute more, and the experiment was not con- 

 sidered accurate unless the thermometer afterwards indicated 

 a slight loss of heat. Finally, the glass vessel was inverted 

 under water, the capillary point of the tube broken, and the 

 weight of the water that rushed in (the levels having been 

 duly adjusted) ascertained. The residual air did not, in 

 general, amount to more than one or two per cent, of the 

 whole, and was in all cases free from the slightest odour of 

 chlorine. 



The determination of the heat evolved during the combina- 

 tion of potassium with chlorine involved experimental diffi- 

 culties, which for some time appeared likely to prove insupe- 

 rable, but were finally overcome by the employment of a some- 

 what novel form of apparatus. The chief source of difficulty 

 arose from the intensity of the heat produced by the conibi- 



