A standard bromine solution is made by dissolving 12 406 grams of potassium bromide and 3.481 grams of potassium bromate in a litre of recently boiled distilled water.

Fifty c.c. of this standard solution (=05 gram of bromine) are placed in a flask of about 200 c.c. capacity, having a well-ground stopper. To this are added 10 c.c. of dilute sulphuric acid (1 in 4), and the whole shaken gently. After a few minutes the wood naphtha is slowly run from a burette into the clear brown solution of bromine until the latter is completely decolorised.

This test serves as a measure of the allyl alcohol and other unsaturated compounds. The result is usually expressed in terms of the volume of naphtha required, since allyl alcohol is not, or is not known to be, the only unsaturated compound present.