DESCRIPTION OF A NEW CALORIMETER* ]QQ 



means of mixture; for in pouring the hot liquid into the in- Inaccuracies 



terior chamber, the pipe of the kettle may enter it, so ttf ° bviatedb 7 



1 r J ' this apparatus. 



entirely to prevent the abstraction of heat, and the vessel 



must act in a similar manner on both fluids. 



It is one of the most important questions in chemistry, to Whether the 



determine, whether or not the capacities of fluids are pei*~-"Pj CI ' ies of 



r r fluids be per- 



manent from 32° to 212°: or in other words, whether 10 manent from 



degrees of caloric, added to water at 32°, will produce the [|j* ^ m ng to 

 same elevation of temperature, as 10 degrees thrown into the point a pro- 

 same quantity at 200°. Most chemists are of opinion, that b ^ d to be 

 water changes its capacity at two points only, in passing The affirma _ 

 from the solid to the fluid, and from the fluid to the aeri*- tive generally 

 form state ; and consequently, that there is a permanency of beheved> 

 capacity between the thermometric range of the freezing 

 and boiling points. Drs. Crawford, Black, Irvine, de Luc, 

 &c. thought they decidedly proved this to be the fact, by a 

 number of experiments; for on mixing equal quantities of 

 water at different temperatures, they found nearly a mean 

 produced. " The air of the room," says Dr. Crawford, Dr . Crawford's 

 ** being 6l'5°, a quantity of water, weighing 13lbs. lOjoz. experiment, 

 was heated in a slight tinned iron vessel, that had a cover of 

 the same metal closely adapted to it, a thermometer being 

 inserted in the centre of the cover by means of a cork. 

 When the water was raised to the desired temperature, it 

 was gently agitated, that every part of it might be brought 

 to the same heat. The thermometer immersed in it point- 

 ing precisely to 120*6°, an equal quantity of cold water at 

 50*9°> the parts of which were also brought by agitation to 

 a common temperature, was mixed with the warm, by pour- 

 ing it into the tinned vessel in which the latter was contain- 

 ed. When the mixture was reduced, by agitating it with a 

 wooden rod to a mean heat, its temperature at the end of 

 one minute was 89*8°. Allowing therefore -066° for the 

 heat lost in the first minute, we have 89*866° for the true 

 temperature of the mixture. If the thermometer at the 

 moment of immersion bad indicated the exact arithmetical 

 mean it would have stood at 89*8.*'* 



I will not here enter into the many difficulties and sources Remark. 

 of inaccuracy attendant on this method by mixture, but 



* Cravrford on Animal Heat. 



merely 



