IOWA ACADEMY OF SCIENCES. 
183 
This is a saturated compound and belongs to what is 
called the “ limit hydrocarbons,” because no more hydrogeii 
can be added to it without decomposing it. 
It is possible that some of the acetylene and some of the 
hydrogen may pass through unchanged. In this case, the 
final product may contain ethane, ethylene, acetylene, and 
hydrogen. 
It has been discovered that concentrated sulphuric acid 
will absorb ethylene very slowly at ordinary temperatures, 
but completely at 174° . Ethane, acetylene and hydrogen 
are, however, unaffected and will, therefore, separate them- 
selves from the ethylene when they are conducted through 
the heated acid. When ethylene is absorbed by the sul- 
phuric acid, it unites with it chemically, forming what is 
known as ethyl sulphuric acid The equation of the re- 
action is: 
H 
C2H4+H 
S04=^^g®S04....(5) 
The solution is now cooled to the ordinary temperature 
diluted with w^ater and boiled. The reaction will give 
ethyl alcohol and sulphuric acid, the alcohol being distilled 
off and condensed. The equation of this reaction is: 
Csy® SO4+H2O—C2H5OH+H2SO4 ... .(6). 
If the sulphuric acid is not concentrated at the end of this 
reaction, the water may be driven off by heat and the re- 
concentrated acid used over again. 
The alcohol thus made has some advantages in purity over 
the product obtained by fermentation, which often contains 
some wood alcohol and traces of higher alcohols some- 
times grouped under the name of ^‘fusel oil.” In order to 
eliminate these as nearly as possible the alcohol is filtered 
through charcoal, which, however, tends to create a new 
impurity — i. e., acetaldehyde. On the other hand, if the 
process is rightly conducted, the chance of anything 
besides ethyl alcohol and sulphuric acid being evolved, 
in equation (6), may be reduced to a minimum and an 
alcohol of greater purity, therefore, may be obtained from 
calcium carbide than from grain . 
