﻿114 CcotaiUan Record of Science. 



will \)it seen LliaL the (lecoiii])()siti()n takes place with a 

 (lull red ilaiiie, as if the acetylene were burning with an 

 insutlicient supply of air. No air, however, is in the 

 tube : there is no combustion in the ordinary use of the 

 word, and yet we have in the Hanie evidence of a sudden 

 <lisengaj^enient of heat. Here we approach the solution 

 of the pr()l)leni, regarding tlie extraordinary chemical 

 activity of acetylene. Acetylene has a supply of heat 

 stored up, which it gives, ofi' whenever it is decomposed 

 spontaneously, burnt in air, or excited by any radical 

 chemical change. The sudden evolution of heat manifests 

 itself as light, quickens combustion and pi"oniotes all 

 chemical action. 



The exact (piantity of heat absorbed and stored up by 

 acetylene, when it fs formed by the union of carbon and 

 hydrogen, can be best measured by two experiments. 

 Firstly, burn exactly one cubic foot of acetylene in a 

 calorimetric apparatus, which is merely a device for 

 heating a given weight of water without loss of heat, 

 and find that nearly nine pounds of water can be heated 

 from its freezing to its boiling point. Or, if we take the 

 thermal unit in more general use we find that 407 kilo- 

 grams of water gain one degree Centigrade in temperature 

 from the heat given ofi* by burning one cubic foot of 

 acetylene gas, measured at 0° Cent, and 76 cm. barometer. 



Secondly, take exactly the weights of carbon and 

 hydrogen wliich correspond to the weight of one cubic 

 foot of acetylene and burn them in the same way under 

 a weighed quantity of water. We shall find that accord- 

 ing as we take pure amorphous carbon or diamonds we 

 get a somewhat different quantity of heat. With amor- 

 phous carbon and hydrogen 336.5 kilograms of water are 

 raised I degree Cent, in temperature. The difference of 

 heating power then between acetylene gas and the same 

 weight of carbon and hydrogen is 71 heat units. The 

 surplus energy stored up in the acetylene and set free 



