OBSERVATIONS ON ETHERIF ICATION. 
271 
the alcohol, to be compared with that which the same acid exhibits 
when mixed in a small proportion with the essential oils. Oil of 
turpentine mixed with one-twentieth of its volume of sulphuric 
acid, undergoes an entire change, being chiefly converted into a 
mixture of two other hydrocarbons, terebene and colophene, one 
of which has a much higher boiling point and greater vapor- 
density than the oils of turpentine. This hydrocarbon does not 
combine with the acid, but is merely increased in atomic weight 
and gaseous density, without any further derangement of compo- 
sition, by a remarkable polymerizing action (as it may be termed) 
of the sulphuric acid. So of the hydrocarbon of alcohol; its den- 
sity is doubled in ether, by the same polymerizing action. Chlo- 
ride of zinc effects, with alcohol, at an elevated temperature, a 
polymeric catalysis of the latter, of the same character, but in 
w 7 hich hydrocarbons are formed, of even greater density and free 
from oxygen. 
This view of etherification is only to be considered as an 
expression of the contact-theory of that process which has long 
been so ably advocated by M. Mitscherlich. 
The formation of sulphovinic acid appears not to be a necessary 
step in the production of ether ; for we have found that the ether- 
izing proceeded most advantageously with bisulphate of soda, 
or with sulphuric acid mixed with a large proportion of alcohol 
and water, which would greatly impede the production of sul- 
phovinic acid. It appears, indeed, that the combination of al- 
cohol with sulphuric acid, in the form of sulphovinic acid, greatly 
diminishes the chance of the former being afterwards etherized ; 
for, when the proportion of oil of vitriol was increased in the 
preceding experiments, which would give much sulphovinic acid, 
the formation of ether rapidly diminished. The previous con- 
version of alcohol into sulphovinic acid, appears, therefore, to be 
actually prejudicial, and to stand in the way of its subsequent 
transformation into ether. 
The operation of etherizing has attained a kind of technical 
perfection in the beautiful continuous process now T followed. The 
first mixture of alcohol and sulphuric acid is converted into sul- 
phovinic acid, the sulphate of ether and water, which acid salt 
appears to be the agent which polymerizes all the alcohol after- 
wards introduced into the fluid. Bisulphate of soda, with a slight 
