Note on a proposed test for halogens
IK the estimation of nitrogen in triazo compounds by shaking with mercury and concentrated sulphuric acid, with alcohol as the solvent (H. D. Richmond, ANALYST, 1908, 33, ISO), it was noticed that when halogen was present, a precipitate of mercurous halide was formed. The following are the results of some experiments made to determine whether this reaction is general, and also if it could be used for the estimation of halogens. The method of procedure was to dissolve the substance in the
... tance in the smallest possible quantity of alcohol, and shake the solution with some mercury and a little concentrated sulphuric acid in a small stoppered bottle. About forty substances have been examined, but only in'the case of some iodine compounds was the precipitate large. With all the other substances the precipitate was very slight, in some cases amounting to little more than a dimmiDg of the surface of the mercury. The influence of the quantity of sulphuric acid present seemed to be small. IODINE CoJIPouNDS.-~vith methyl, ethyl, propyl, and methylene iodides, a good precipitate was produced ; but with iodoform and iodobenzene the precipitate was very slight. BROAIINE Com?ouNDs.-These included ethyl bromide, ethylene dibromide, bromoform, acetylene tetrabromide, bromethylene bromide, tribromacetic acid, monobrombenzene, p-dibrornbenzene, 21-bromtoluene, nz-brombenzoic acid, dibromanthracene, and bromtriphenylmethane.