After cooling, the contents of the flask are diluted with water, the green color giving place to a brown with a rise of temperature. After cooling a second time the whole is brought into a distillation flask of about three-quarters of a liter capacity and attached to a condenser which ends in a vessel containing titrated sulfuric acid. About forty cubic centimeters of sodium hydroxid solution of one and three-tenths specific gravity are added and the stopper at once inserted to prevent any loss of ammonia. To prevent bumping during the distillation some zinc dust is added securing an evolution of hydrogen during the progress of the distillation. In this case the bumping is prevented until near the end of the operation when it begins anew, probably by reason of the separation of solid sodium sulfate. After the end of the distillation, the excess of acid remaining in the receiver is determined by a set alkali solution and thus the quantity of ammonia obtained easily calculated. Kjeldahl, however, preferred to titrate the solution after adding potassium iodate and iodid, a mixture which in the presence of a strong acid sets free a quantity of iodin equivalent to the free acid present. The iodin thus set free is titrated by a set solution of sodium thiosulfate using starch as an indicator. The merits of this method are sharpness of the end reaction and the possibility of using only a small quantity of the nitrogenous body for the combustion. The sulfuric acid used in the receiver is made of the same strength as the thiosulfate solution; _viz._, about one-twentieth normal. Thirty cubic centimeters of this were found to be the proper amount for use with substances taken in such quantities as to produce ammonia enough to neutralize about half of it. The titration is carried on as follows: A few crystals of potassium iodid are dissolved in the acid mixture obtained after the distillation is completed, then a few drops of the starch-paste and finally a few drops of a four per cent solution of potassium iodate. The iodin set free is then oxidized by the addition of the one-twentieth normal sodium thiosulfate solution until the blue color disappears. _Example_: Sulfuric acid used, 30 cc. Equivalent to sodium thiosulfate, 30 cc. Blank combustion required, 29.8 cc thiosulfate solution. Combustion of 0.645 gram of barley 14.5 cc “ “ required, ------- Thiosulfate corresponding to barley, 15.3 cc. In the computation it is more simple to multiply the corresponding number of cubic centimeters of thiosulfate by seven, half the atomic weight of nitrogen, and divide the product by the weight of the substance taken, which will give the per cent of nitrogen therein. 15.3 × 7 Then ---------- × 100 = 1.66 = per cent of nitrogen in sample taken. 0.645