There are numerous articles concerning the estination of total sulfur in organic substances and yet the results obtained hitherto are not by any means quite satisfactory. The gratest difficulty encountered in the estination of sulfur seems to lie in the insufficient ashing of the substance. Therefore, the author studied various ashing metheds and finally modified Bethge's wet ashing in the following manner: 1, Ammoniated vanadium (NH(4)VO(3)) is added as an oxidizing catalyst. 2. As an indicator of the complete oxidation potassium chromate (K(2)Cr(2)O(7)) is used. 3. The ratio of acid mixture is set in the proportion of three parts perohloric acid to two parts nitric acid. 4. The reduction mixture is placed into an ampule filled with pitrogan immediately after it is prepared and is sealed tightly, and the quantity of the mixture to be added is increased. By the modified method mentioned above it has been possible to raise the recovery rate of sulfur added as much as 95.4 per Gent, proving that this method is sufficiently useful for the estimation of the total sulfur in milk, urine and faces. In the estimations of total sulfur of various milk such as breast milk, milk on the market and 18% solution of regulated powered milk the average contents of total sulfur have been found to be 11.7 mg and 31.8 mg per dl respectively.