378 Dr. Woods on the Amount of Heat produced by the 



grains of zinc being oxidized would raise the temperature of 60 

 grains of water 159°'8 ; therefore the difference between 159°'8 

 and 129"-8j equal to 30°-'i F., is absorbed by the decomposition 

 of the acid. 



Bismuth. 



8-9 grains of bismuth by their solution in nitric acid develope 

 sufficient heat to raise the temperature of 60 grains of water 

 80°- 1 F. Subtract 36° for the heat of combination of the acid 

 and oxide, and add 30°--l for the absorption of heat by the de- 

 composition of the acid, and the result is that 1 equivalent of 

 bismuth produces by its combustion as much heat as would raise 

 60 grains of water 74°-5 F. 



Lead. 



13-7 grains, or 1 equivalent of lead, by its solution in nitric 

 acid produce lieat sufficient to raise the temperature of 60 

 grains of water 106° F., including 37° F. for the combination of 

 the oxide with the acid ; the latter being subtracted leaves 69°, 

 to which must be added 30°-4 for the amount absorbed by the 

 decomposition of the acid, and there remains 99^-4. F. as the 

 amoimt of heat produced in 60 grains of water by the combus- 

 tion of 1 equivalent of lead. 



Mercury. 



I could not ascertain satisfactorily the amount of heat pro- 

 duced by the oxidizement of mercury. Its solution in nitric 

 acid is slow, and its equivalent number is high, and the combi- 

 nation it forms with the acid is not well ascertained. It is ge- 

 nerally thought that when there is an excess of acid the salt 

 formed is a swi-salt, Hg^O being the base ; if such be the case, 

 25 grains of mercury raise the temperature of 60 grains of water 

 50° F., including the combination of the oxide with the acid, 

 and this produces sufficient heat to raise 60 grains of water 40°. 

 The oxidizement alone produces 50°— 40° = 10° F. ; to this sum 

 add 30°'4 for the heat absorbed by the decomposition of the acid, 

 and it leaves 40°-4 F. as the quantity of heat produced in 60 

 grains of water by the combustion of 1 equivalent of mercury. 



Silver. 

 I3i grains, or 1 equivalent of silver, by its solution in nitric 

 acid raise 60 grains of water 40°-5 F. ; subtract 32° for the 

 heat produced hy the combination of the acid with the oxide of 

 silver, and add 30°'4 for the heat absorbed by the decompositioQ 

 of the acid, and 38°"9 F. is the number of degrees 1 equivalent 

 of silver by its oxidizement would raise 60 grains of water. 



The amount of heat produced by the oxidizement of iron could 

 not be calculated with any certainty from its solution in dilute 



