T H E 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



MAY 1848. 



XLV. On the Heat disengaged during the Combination of 

 Bodies with Oxtjge?i and Chlorijie. By Thomas Andrews, 

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



[With a Plate.] 



§ I. Comhinatio7i of O.iygen with the permanent Gases. 



'^1 "'HE determination of the quantity of heat evolved during 

 the combination of oxygen with hydrogen has occupied 

 at different periods some of the most distinguished cultivators 

 of chemical science, among whom we may cite the names of 

 Crawford, Lavoisier, Dalton, Davy, and in more recent times, 

 of Despretz and Dulong. The heat produced in other cases 

 of gaseous combination has been made the subject of investi- 

 gation by Dalton, Davy and Dulong; but the methods em- 

 ployed by the two former were so defective as to render their 

 results of comparatively little value. 



The experiments of Lavoisier were performed with his ca- 

 lorimeter, an instrument capal)le of yielding accurate results 

 in certain cases, and when all due precautions are taken, but 

 for obvious reasons now rarely, if ever, employed in investi- 

 gations of this kind. Of the method employed by Despretz 

 no detailed description, so far as I am aware, has been pub- 

 lished. From the brief notice given by M. Cabart, we are 

 made actjuainted with the general form of apparatus employed 

 by Dulong. It is evident from this description that Duiong's 

 mode of operating must have been entirely different from that 

 adopted in the present investigation. This circumstance 

 should be kept in mind in comparing the results. 



In the following experiments, the mixtures of the gases, 

 prepared in the same manner as for a common eudiometric 



• Extracted from a memoir communicated to the Acadciny of Sciences 

 of Paris in Marcli 184.i. 



I'hil. Mag. S. 3. Vol. 32. No. 2 1 6. Maij 1 84b. Y 



