188 
IOWA ACADEMY OF SCIENCES. 
The next problem is to convert the aldehyde into ethyl 
alcohol. Equation (13) represents the requisite reaction. 
It is impossible to simply lead the hydrogen gas into the 
acetaldehyde and make it unite chemically with it to form 
alcohol. The hydrogen must be in the nascent state, -i. e., 
the condition in which it is after it is first evolved and 
before it has formed into atoms. It is the ionic state. 
When sodium or potassium are placed in water, they 
liberate nascent hydrogen and form the caustic alkalis 
thus: 
K + H20=H + K0H....(14). 
The hydrogen, liberated in this way, however, is evolved 
so rapidly as to be unfit for application in a chemical 
reaction. The potassium is first united with metallic mer- 
•cury to form what is called potassium amalgam, and this 
is used in place of the metallic potassium. Potassium 
amalgam may be formed by simply bringing the potassium 
into contact with the mercury. The reaction evolves a 
great deal of heat and the product is a solid resembling 
zinc in appearance. When potassium amalgam is placed 
in water, the reaction is very slow, the particles of hydro- 
gen being so broken up as to give the solution a milky 
appearance. The same reaction takes place as represented 
in equation (14), and the mercury is left in the metallic 
state at the bottom of the solution. 
In order to apply the reaction to the acetaldehyde, the 
aldehyde is diluted freely with water and the mixture then 
treated with the potassium amalgam. The reaction is that 
expressed in equation (13) and the product is ethyl alcohol. 
Two reactions tending to form by-products, at this stage, 
must be guarded against. The caustic alkali, which forms 
during the reaction, has a marked tendency to polymerize 
the acetaldehyde; and the potassium will, if proper pre- 
cautions are not taken, decompose the alcohol formed, 
liberate hydrogen from it, and unite with the alcohol radi- 
cal to form potassium alcoholate. The most nearlj^ 
effective means of preventing these side reactions is to 
have an excess of water, which will eliminate the forma- 
