IOWA ACADEMY OF SCIENCES. 
189 
tion of alcoholate and tend to decrease the polymerization 
of the aldehyde by making the solution of caustic alkali 
more dilute and consequently less active. The solution 
should also be kept at as high a temperature as it may be 
without causing the aldehyde to vaporize, because the poly- 
merization of the aldehyde is more likely to occur at low 
temperatures. The greater the excess of water, the higher 
may the temperature of the solution be raised without 
liberating the aldehyde. When the action has been com- 
pleted, the alcohol may be distilled off. 
If the potassium amalgam were to be formed each time 
from metallic potassium, the process just outlined would 
be highly impractical, because of the cost of the potassium. 
However, the entire amount of potassium amalgam con- 
sumed in the above reaction may be very simply recovered 
each time and used over and over again for an indefinite 
length of time. The process is this: After the solution 
containing the alcohol has had all the alcohol distilled 
from it, it is boiled down till the solution of potassium 
hydroxide is a supersaturated one, and will remain so dur- 
ing the reaction which is to follow. The positive pole of 
an electric circuit is now placed in the metallic mercury 
and the negative pole is immersed in the solution of potas- 
sium hydroxide. The current in passing through the solu- 
tion will again unite the potassium with the mercury. 
The amalgam will have no tendency to decompose as long 
as the solution of potassium hydroxide remains concen- 
trated. In this way the cost of metallic sodium or potas- 
sium may be entirely ignored. 
Another method of combining acetylene and water to 
form aldehyde is to run acetylene gas into moderately 
dilute sulphuric acid, which has had its temperature raised 
to about 100® , cooling the solution to the ordinary tem- 
perature and diluting with water. The solution is then 
distilled when acetaldehyde will be given off in greater or 
less amount. This is, however, a very unsatisfactory 
method, because of the formation of by-products, the chief 
