On Serum Copper. II. Technique of Analysis.

Summary. Description is given of the author's modification of M cfarlane's M ethod for determination of the copper content of blood and serum by means of diethyl‐dithiocarbamate. Experiments show that acid ashing and trichloroacetic acid treatment give the same results. For alkalinization the addition of ammonia in excess is unsuitable as it may be precipitated in the amyl alcohol as ammonium carbonate. In determinations on whole blood the presence of iron after ashing may cause an error which is avoided most easily by adding the thiocarbamate dissolved in a solution of pyrophosphate.