DENATURED ALCOHOL 249 



little lower in temperature than the one beneath it. The alcohol vapor 

 and water vapor from the still beneath pass through this dephlegmator, 

 and it is readily seen that much of the water and some of the alcohol 

 must condense in it and trickle back into the still. Inasmuch as alco- 

 hol condenses at a lower temperature than water it has the better 

 chance to pass clear through, and into the condenser and receiver. 

 Many modifications of this machine are on the market and they are 

 all efficient. It is an easy matter, with it, to obtain 80 per cent, to 90 

 per cent, alcohol, and not difficult to obtain 95 per cent, alcohol. The 

 last four or five per cent, of water clings hard to the alcohol and can 

 not be removed by distillation alone. If it is desired to make yet 

 purer alcohol, some substance such as lime, which combines eagerly 

 with water, must be added to hold the water back, and then practically 

 pure alcohol may be distilled off. Pure alcohol containing no water 

 (100 per cent.) is known as absolute alcohol. But such pure alcohol 

 is needed only for a few special chemical processes ; there is no general 

 demand for anything better than 95 per cent. Indeed, absolute alco- 

 hol has what may be called an avidity for water; it is hygroscopic, and 

 if left in an open bottle will soon collect moisture out of the air and 

 dilute itself. 



It is evident that any distillery in the country — and there are about 

 one thousand of them producing upwards of one hundred and fifty 

 millions of ' tax gallons ' a year — can increase its output to correspond 

 to the demand which may spring up. The permission to market the 

 product free of tax, if denatured, will then, in the first instance, merely 

 furnish another outlet for the products of these distilleries. A new 

 factory will find itself immediately in competition with the old estab- 

 lished plants. 



The question next arises, are there any methods of making alcohol 

 other than those by which spirituous liquors are made? In the sense 

 that spirituous liquors are essentially nothing but more or less dilute 

 alcohol such other methods are obviously impossible. But there are 

 methods starting with very different raw materials. 



Berthelot, the French chemist, long ago showed how ethyl alcohol 

 might be made synthetically from inorganic materials. The destruc- 

 tive distillation of coal gives us coal gas, and one of the constituents 

 of this is ethylene. This ethylene will dissolve in sulphuric acid form- 

 ing ethyl-sulphuric acid. If we add water and distil, ethyl alcohol is 

 given off and collects in the receiver, while the sulphuric acid may be 

 recovered in its original condition. At the present time we can start 

 even farther back than Berthelot's starting point. A mixture of lime 

 and charcoal heated in an electric furnace will give us calcium carbide. 

 This calcium carbide, with water, will give us acetylene, and the acety- 

 lene will combine with hydrogen to form ethylene. Then the rest of 



