170 ON THE PASSAGE OF HEAT THROUGH FLUIDS. 



It cannot be It may be fuppofed perhaps, that the quantity of caloric thus 



mXHiS^t conve J ed b )' the veflel W*»H not be fufficien^ to produce the 



happens. rile of temperature which took place in thefe experiments. 



But how is this to be afcertaincd. It may appear probable, 



but until it is proved, the point muft remain doubtful, and the 



experiments mull be therefore inconclufive. 



To furrovnd the Jt was an obvious idea, that this fource of error might per- 

 veflfel externally , , , . , . r , r , ° _ . 



with water ' na P s De obviated in a great mealure by iurrounding the veflel 



with water, which would carry off the caloric conveyed by 

 its fides. It is evident, however, that it could carry off only 

 part of it, for part muft ftill continue to be abftracied from the 

 internal furface by the water in contact with it. And even 

 the quantity taken from the external furface of the jar by the 

 water furrounding it, would be only fomewhat greater than 

 what would be carried off by the afmofphere w f hen the expe- 

 riment was performed as defcribed above, 

 pmmifed to be The experiment however of furrounding the veflel with 



of ome u e. wa £ er might afford fome information : it would at leaft prove, 

 .Experiment. ■ . 



Heat was found that caloric was conveyed by the fides of the veflel, and it 



to defcend in m ight indicate in fome meafure the quantity conveyed. I ac- 

 the internal and to . . . l J f.-,. 



external water, cordingly performed it in the manner repreiented in Fig. 2. 



D being merely a cylindrical glafs veflel fix inches in diameter, 

 in which the apparatus ufed in the former experiments was 

 placed. Water was poured into it, to the fame height as in 

 the internal veflel, and a thermometer was fufpended in the 

 water, the bulb being at precifely the fame diftance from the 

 furface, as the bulb of the bent thermometer in the veflel A. 

 The brafs ball heated to 212° was fufpended in the water in 

 the latlqr veflel, and at the fame diftance from the thermometer 

 as in the preceding experiments. The following were the 

 refults. At the commencement of the experiment,, both 

 thermometers were at 46°. 



In 3 minutes, the internal thermometer 



A 46 j the external E ftill 46 



5 min. 47 1 4«i 



10 - - - - 48| 47-| 



1.5 - - - - 49 J - 48 J 



20 - - - - 4ij 48J 



30 - - - - 49 - 48 



Many reafons This experiment proves nothing more, than that a quantity 



why thisexperi- y caloric is conveye( | by the fides of the veffel. It might 



perhaps 



