ON LATENT »EAt, 47 



it was partially folid, at which time I inferred that both the Blfmuth, on the 



folid and fluid metal were of the temperature of 476^. I next j^g" was'poured" 



poured a portion of the fluid bifmuth into the water. In one into water, the 



minute tiie thermometer ftood at 86° ; in two minutes at 85| : ^"'J'/j^^^/^' ^^' 



The true temperature at the moment of mixture was therefore being known j 



86'|, Cuppofing equal temperatures to be loft in equal intervals. JJ*^ tratuTTas 



There was alfo a quantity of fleam formed. I weighed thetalcsn. 



veflel with its contents, and found that it had gained 1589 



grains. This therefore ftiould be the quantity of bifmuth 



poured in, if there had been no lofs. But on drying and 



weighing the metal, it appeared to amount only to 1555 



grains, and St grains confequently were loft. The bifmuth 



was cooled 389|^, the water was heated 24|®. Then 1555 



grains of water would have gained 34?. Thefe 34^, meafured 



by the fpecific heat of bifmuth, as ftated in Thomfon's Syftem 



of Chemiftry at .042, are equal to 810^9 : But the bifmuth, 



after becoming folid, loft 389^.75, which being fubtracfed 



from 810.9, there remains 421**. 15, which cannot be account-Inference of the 



ed for by the cooling of the folid bifmuth, and muft therefore ^^'«"' *^^a^* 



be the whole or a part of the latent heat of the fufed metal. 



But the latent heat muft be greater than this, for 41 1 grains Correftion, for 

 of glafs were alfo lieated 24°. 25. If the capacity of this glafs ^^^ ^^^«^ > 

 be taken at .174, as Kirwan found flint glafs to have, and I 

 have found green bottle glafs to have a capacity of .173 by 

 feveral experiments, whence it is probable that the glafs of 

 Florence flalks has its capacity not very wide of thefe num- 

 bers; if then .174 be taken as the capacity of this glafs, thete 

 24^.25, which the bifmuth communicated to the 41 1 grains 

 of glafe in the vefl^el, are, when meafured by the capacity of 

 bifmuth, equal to 96°;4 : And 1555 grains of glafs would have 

 gained 25°.4, which muft be added to 421^.15 already found, 

 and makes 446*. 55 for the latent heat of bifmuth. 



But this is obvioufly ftill too little ; for, as has been already and for fteam 

 mentioned, there was a good deal of fleam formed. The^^° " 

 amount of the heat thus loft is extremely difficult to aflign. I 

 fliall, however, make an attempt to guefs at, rather than de- 

 termine it. AH the 34 grains muft not be reckoned to have 

 been loft by evaporation. In fpite of all my efforts, I could 

 perceive that tome, though certainly a fmall quantity of bif- 

 muth went off with the water, in form of a number of fmall 

 particles floating in the liquid ; and perhaps alfo a fmall por, 



tion 



