230 Nature's flfciracte*. 



formation to the direct current, as is necessary 

 in the manufacture of bleaching-powder and 

 aluminum, both of which are electrolytic proc- 

 esses. 



When the operation is completed the cur- 

 rent is turned off and the compound allowed 

 fo cool. In cooling it assumes a slate color, 

 which is slightly iridescent when exposed to 

 light. It also crystallizes to a certain extent. 



The value of this new product consists in 

 its ability to evolve Acetylene gas in large 

 quantities. A molecule of acetylene gas is 

 composed of two atoms of carbon to two of 

 hydrogen. To evolve the gas it is necessary- 

 only to pour water upon the calcium carbide, 

 when a union takes place between the carbon 

 of the carbide and the hydrogen of the water 

 in the proportions above stated. If there is 

 water enough the whole of the carbon will pass 

 off with the gas, leaving a residuum of slacked 

 lime. 



The value of acetylene gas lies in its very 

 intense illuminating power. This is due to 

 the fact that the gas is very rich in carbon as 

 compared with other illuminating gases. It 

 burns with a pure white light when properly 

 mixed with air or oxygen, but if there is a lack 

 of air it burns with a smoky flame. In this 

 case the carbon is not all consumed and es- 

 capes into the air in the form of soot or smoke, 

 but when burned with the proper mixture of 



