in Comlustion, and in the Condensation of Vapours. 291 

 It.woalil seem frcm the results of this experiment, that 

 the water in the secondary receiver only began to be per- 

 ceptibly heated after that which had been in the prmcipal 

 receiver had been already heated from 15 to 20°; and as I 

 proposed to mvsclf, from the commencement of this work, 

 never to continue an experiment longer than the lenipera- 

 ture of the water in the principal receiver was raised to 10 

 or 12^ F. it may be conceived that as soon as 1 had learnt 

 by this experiment how much heat remains in the products 

 of the combustion, after they have passed through the 

 worm from the principal receiver, I renounced the project 

 which I had first conceived of working with the two re- 

 ceivers joined together. As it was evident, from the re- 

 sults of this experiment, that the second receiver could 

 never be sensibly affected, or indicate any thing, notwith- 

 standing the confidence which I ought to have in the m- 

 dications of the first, 1 have taken the resolution to get rul 



VVe shall see by the description which I have given of 

 this apparatus, that we may make use of it very conveniently 

 in order to determine the specific heat o^ the gases, as well 

 as that which is manifested in the condensation ot vapours, 

 and generally in all the researches for measuring the quan- 

 titv of heat' communicated by a given elastic fluid in its 

 coolin-r; and as it would be very easy, by a simple process, 

 to separate completely the products of ihe vapours con- 

 densed in the worm, and of the ga.es which pass through 

 it without being condensed, I do not retrain from hoping 

 that this apparatus will become useful as an instrument to 

 be employed in chemical analyses. Besides, this will be 

 onlv an extension of the method already employed with 

 so much success by M. Saussure and by Messrs. Gay- 

 Lussac and Thenard. ^ . , , t 



As soon as my apparatus was finished, I was anxious to 

 ascertain whai mianiity of heat I should find in the com- 

 bustion of «ax anrl of olive oil, that I might afterwards 

 compare rhe results of mv experiments with those ot 

 M.Lavoisier; and as \ have the most implicit confidence 

 in everv thing which this most worthy man has published, 

 I was desirous to find in this comparison a proot ot th& 

 exactitude of my method, and at the same time a confirma- 

 tion of M. Lavoisier's calculations. 



§ \. Heat developed in the Combustion of IVax. 

 The air of the room being at the temperature "f 61" F. 

 27bl t-rammes of water at the temperature of QG," F. were 

 ° 'J- 2 placed 



