This instrument is sometimes called Richters alcoholometer, in England.
Field's alcoholometer, since improved by Ure, is based upon this principle.
I have never attempted to collect quantities of alcoholics without an alcoholometer in constant use.
Therefore I say, buy an alcoholometer at all hazards, and carry it and a suitable test-glass with your outfit.
The spirit used should be reduced to about proof, and the traveller should always be provided with an alcoholometer.