Combination of several Metals with Oxygen. 377 



The amount of Heat produced by the Oxidizement of an equivalent 

 of Sodium. 

 3 grains of sodium by dissolving in water raise the tempera- 

 ture of 60 grains 154° E., decomposition of water to supply 1 

 grain of oxygen absorbs 130°; therefore the 3 grains of sodium 

 (or 1 equivalent) raise the temperature of 60 of water 154 + 130 

 = 281° F. by combining with oxygen. 



Potassium. 



5 grains of potassium raise the temperature of 60 grains of 

 M-ater by dissolving in it 126°-5 F.; add 130° for the heat 

 absorbed by the decomposition of the water, and 256°-5 F. is the 

 amount of heat liberated by the combustion of 1 equivalent of 

 potassium. 



Zinc. 



The solution of 4 grains of zinc in sulphuric acid (dilute) pro- 

 duces heat sufficient to raise 60 grains of water 72° F. The 

 combination of the oxide formed and the sulphuric acid developes 

 in the same quantity of water 42°-2 F ; this must therefore be 

 subtracted from the 72°, as it is not due to the oxidizement of 

 the zinc, and there then remains 29^-8; but to this quantity 

 must be added 130° absorbed by the decomposition of the water, 

 and 159°- 8 F. is the amount of heat that the combustion of zinc 

 would produce in 60 grains of water. 



Copj^er. 

 Copper will not decompose water ; nitric acid was therefore 

 substituted for the dilute sulphvu-ic acid. 3-96 grains, or 1 

 equivalent of copper, by dissolving in nitric acid raise the tem- 

 perature of 60° grains of water 77°-22 F. ; but in this is included 

 the amount of heat produced by the combination of the oxide of 

 copper with the nitric acid, which is 35° F. Subtract this sum, 

 therefore, and 42°-22 remain ; but as the decomposition of suf- 

 ficient nitric acid to give one grain of oxygen would absorb as 

 much heat as would lower the temperature of 60 grs. of water 

 30°-4 F., this must be added to the 42°-2 F., and we obtain 

 72°-6 F. as the amount of heat produced in 60 grains of water 

 by the combustion of copper. 



The manner in which I found that the decomposition of nitric 

 acid absorbs the above amount of heat was by dissolving 4 grains 

 of zinc in 180 grains of the acid; it liberated heat sufficient to 

 raise 60 grains of water 171°-7 F. As this included the heat of 

 combination of the oxide of zinc and nitric acid, 42°-2 must be 

 subtracted, and there remains 129°-8 F. ; but in the former cx- 

 penmcnt with the dilute Ku]j)huric acid, it was shown that 4 



