Combination of several Metals with Oxygen. 379 



sulphuric acid, as it' requires a large amount to be dissolved to 

 cause a perceptible rise of temperature. The heat it produces 

 must be very nearly the same as that produced by hydrogen, as 

 if it differed considerably, a small quantity of it would give rise 

 to a large amount of heat, as its equivalent is small. The heat 

 absorbed by the decomposition of the water very nearly balanced 

 that produced by the combination of the iron with the oxygen. 

 Iron produces only a very little more, if more at all, heat with 

 oxygen than hydrogen does. "\'\Tien iron is dissolved in nitric 

 acid, the peroxide is formed ; and 2i grains, or 1 equivalent, (for 

 2^ grains unite with 1 grain of oxygen), when dissolved in nitric 

 acid, produce heat sufficient to raise 60 grains of water 102° F. 

 As 1 equivalent, or 10 graius of peroxide of iron, by combining 

 mth acid produces heat sufficient to raise 60 grains of water 

 20° F., 3i grains must raise it 6°; subtract this number from 

 102°, there remains 96, and add 30'4 for decomposition of the 

 acid, and 126°-4 F. is the quantity of heat produced by the oxi- 

 dizement of iron. 



Tin. 

 When tin is dissolved in nitric acid, 3^ grains take 1 grain of 

 oxygen to form the ]Deroxide, and raise the temperature of 60 

 grains of water 105° F. If the combmation of the peroxide with 

 the acid produces the same amount of heat as the peroxide of 

 iron does, 6° must be subtracted ; there remains 99^ ; add 30°"4 

 for decomposition of acid, and 129°'4F. is the number of degrees 

 the oxidizemeut of tin would raise 60 grains of water. 



The following table gives at a glance the number of degrees 

 Fahrenheit that one equivalent of each metal, by its combination 

 with oxygen (1 grain), would raise 60 grains of water. In the 

 second column are the results that Andrews arrived at for such 

 of the metals as he has experimented with by directly burning 

 them in oxygen, calculated to the same standard as my own, 

 viz. the quantity of heat their combustion would produce in 60 

 grains of water. 



