densers for from twenty-four to thirty hours, the others during The evidence that the organic nitrogenous groups as given ACID AMIDES. On evaporation to dryness of 1500 cc. (0.13110 gr. nitrogen) Another portion of the double salt was, on solution in hot. and evaporated to dryness. The perfectly white residue when heated in a test tube readily sublimed filling the tube with white fumes which condensed on the cooler parts of the tube. The sublimate showed all the reactions characteristic of ammonium chloride. DIAMINO ACIDS. The residue in the Kjeldahl flask-obtained from the distillation with magnesia of 1000 cc. of the extract S,-was thoroughly extracted with ammonia-free hot water, the extract concentrated to 100 cc. and treated with PTA. The precipitate supposed to represent the diamino acids was next treated with baryta, the filtrate from the insoluble barium salt treated with CO, and the filtrate from barium carbonate evaporated to a few cc. With the smaller part of this liquid the following tests were made: 1. It showed a strongly alkaline reaction. 2. PTA gave a heavy, white precipitate. 3. Phosphomolybdic acid yielded a yellow precipitate. 4. Mercuric chloride gave a grayish precipitate. 5. Silver nitrate gave a grayish-white precipitate soluble in excess of ammonia. 6. Addition of neutralized formaldehyde brought about acid reaction in the strongly alkaline liquid. The greater part of the liquid, having remained after these qualitative tests were made was put into a 2-dm. tube and observed in the polariscope. Mean of several readings was a =+0.12. MONAMINO ACIDS. The filtrate from the PTA precipitate considered to contain monamino acids-was freed from PTA with baryta, excess of the latter removed with CO2, the barium carbonate filtered out and the filtrate repeatedly evaporated until the inorganic salts began to crystallize. The mother liquors on being separated from the salts by suction were united and used for the quantitative determination of the monamino acids by the formol-titrimetric method. PLOT J. 4x50 grams of the air-dry soil mixed with 4x900 cc. of 20 per cent hydrochloric acid were boiled in four round bottom flasks under reflux condensers for 20 hours. On cooling contents of flasks were made up with distilled water to a definite volume and filtered through dry filters, the filtrates having been united in one large bottle. This liquid (s1) served for a number of experiments. By oxidation after Kjeldahl of two 200 cc. portions of the liquid s1 it was found that 1 cc. of it is equal to 0.0000853 gr. nitrogen. It was further ascertained that the nitrogen extracted from the soil was equal to 76.23 per cent of the total soil nitrogen. 1500 cc. of the liquid s1 equal to 0.12795 gr. nitrogen were separated into the various organic nitrogenous groups exactly in the same way as described in Plot E. The results are given below: The proof that the groups contained in Table XI actually represent acid amides, diamino acids and monamino acids is given below. ACID AMIDES. 1230 cc. of the liquid s' equal to 0.10492 gr. nitrogen were evaporated to dryness and distilled in a Kjeldahl flask with cream of magnesia. The residue (a) in the Kjeldahl flask contained the diamino acids and monamino acids, while the distillate contained amido nitrogen in the shape of ammonia which was absorbed in hydrochloric acid. It was next evaporated to dryness and taken up with water. To this platinic chloride was added, evaporated on the water bath to a syrupy consistency, cooled, treated with 80 per cent alcohol and set aside for some time. The alcohol was then separated by suction. from the crystals which were washed with alcohol and dried at 100° C. 0.5076 gr. of the crystals left on burning 0.2243 gr. equal to 44.19 per cent platinum. A portion of the platino-chloride was dissolved in hot water and treated with hydrogen sulphide. The platinic sulphide was filtered out and washed with hot water. Filtrate plus washings were evaporated to dryness, taken up with water, decolored with bone black, filtered and evaporated to dryness. The residue which was perfectly white was heated in a test tube. It at once started to sublime under evolution of white fumes which filled the tube and condensed on the cooler parts. These could be driven forward according as heat was applied. The substance yielded all the reactions of ammonium chloride. DIAMINO ACIDS. The residue a in the Kjeldahl flask was repeatedly extracted with hot water, the extracts evaporated to 100 cc. and separated by means of PTA into diamino acids (precipitate b) and monamino acids (filtrate c). In order to set free the diamino acids the precipitate b was treated with barium hydroxide, the insoluble phosphotungstate filtered out and thoroughly extracted with water. Into filtrate plus washings CO2 was introduced, the barium carbonate filtered out, the filtrate evaporated to a few cc., taken up with some water and filtered. This filtrate showed all the reactions displayed by diamino acids. (See, e. g., page 19.) MONAMINO ACIDS. The filtrate c was freed from PTA by means of baryta the excess of which was removed with CO2, whereupon the barium carbonate was filtered out and the filtrate repeatedly evaporated for the removal of the inorganic salts which on crystallization were separated from the mother liquors by suction. The remaining filtrate was used for the quantitative determination of the monamino acids by the formol-titrimetric method. PLOT N. The nitrogen from the soil of this plot was extracted in five round bottom flasks each of which contained a mixture of 50 grams air-dry soil and 750 cc. of 32.5 per cent hydrochloric acid. After boiling for from twenty-four to thirty hours, the flask contents were cooled, filled to a definite volume, shaken and filtered through dry filters. All filtrates were united in one large bottle which was thoroughly shaken. By oxidizing two portions of 200 cc. of this liquid (s,) it was found that 1 cc. of it is equal to 0.0000964 gr. nitrogen. A portion of s,, namely 1500 cc. equal to 0.14460 gr. nitrogen, was subjected to separation into acid amides, diamino acids, and monamino acid with the result contained in Table XII. It is based on the fact that 72.81 per cent of the total soil nitrogen were obtained in solution. The demonstration that the nitrogen of the organic groups in Table XII is in fact composed of amido, diamino and monamino nitrogen is given herewith. ACID AMIDES, DIAMINO ACIDS AND MONAMINO ACIDS One thousand six hundred eighty cubic centimeters of the liquid s, equal to 0.16195 gr. nitrogen were on evaporating to dryness distilled with cream of magnesia in a Kjeldahl flask, the distillate having been absorbed in hydrochloric acid. The platinochloride prepared as already described elsewhere analyzed as follows: 0.0752 gr. of the platinochloride yielded on burning 0.0330 gr. equal to 43.88 per cent platinum. u.1532 gr. of the platinochloride yielded on burning 0.0673 gr. equal to 43.93 per cent platinum. Average of both analyses is 43.91 per cent platinum which is exactly the percentage required by the formula PtCl,' 2NH,CI. Another portion of the platinochloride having been decomposed with hydrogen sulphide yielded a salt the reactions of which as well as the behavior in the test tube were those of pure ammonium chloride. The residue in the Kjeldahl flask considered to contain diamino acids and monamino acids was twice extracted with hot water, the extracts concentrated to 100 cubic centimeters and separated by means of PTA. The organic acids in question were obtained in solution in a free state as outlined at another place in this bulletin. The solution supposed to contain the diamino acids showed all the reactions displayed by such compounds. The practically neutral solution supposed to contain monamino acids showed a |