It results, then, from these laws that we may determine with the greatest exactness the richness of a solution containing alcohol and water, if we know the tension of the vapors that it gives off at a certain temperature. Such indications are confirmed by the centigrade alcoholmeter.
We see likewise that, for these solutions of alcohol and water, the laws of Dalton are completely at fault, since the total pressure of the vapors is never equal to the sum of the tensions of the two liquids, water and alcohol.
II. Being given a solution of water and alcohol, mixed in equal volumes, what will be the quality of the vapors emitted from it?
In other terms, do the vapors which escape from a definite mixture of water and alcohol also contain volumes of vapor of water and alcohol in the same proportion as the liquids?
We have discovered the following laws:
d. The quality of the vapors emitted by a mixture of water and alcohol varies according to the alcoholic richness of the solution, but is not in simple proportion thereto.
e. The quality of the vapors emitted by a definite mixture of water and alcohol varies according to the temperature.
f. In a same solution of water and alcohol, it is at low temperatures that the vapors emitted by the mixture contain the largest proportion of alcohol.
g. The more the temperature rises the more the tensions of the two liquids tend to become equalized.
We have been able to verify these different laws experimentally, and to find an interesting confirmation of our general formula of maximum tensions, in the following way: