C. Adulteration with Alcohol.
This frequent adulteration is demonstrated either by fractional distillation, when the alcohol passes over first between 70° and 80° C. (158° and 176° F.), or by the use of the vessel illustrated in Fig. 31, which is divided into 100 equal parts.
Fig. 31.
The vessel is filled to the tenth division with the oil to be tested, and water is added to bring the volume to the 50 mark. If alcohol is present, it is taken up by the water so that the volume of oil appears to diminish. If the oil reaches to the mark 7, it contained three volumes of alcohol, or in other words it was mixed with thirty per cent of alcohol. It is true, essential oils likewise dissolve somewhat in water, but in such minute quantities as not to affect the success of the test.