Nov.,
I ~I I
T H E JOLiRiZ‘AL OF I X D U S T R I A L AIVD E,YGI.YEERISG CHEJTISTRY
only that part passing readily being used ; the potash was added in one series as sulphate, in a second as muriate. The mixture contained about 8 per cent, CONTRACTS LABORATORY, of potash and 7.8 per cent. of phosphoric oxide soluble BUREAUOF CHEMISTRY, in water, in addition t o the phosphoric oxide in the WASHINGTON. tankage, which was not determined. The ingredients were thoroughly mixed and portions weighed out NITRIC NITROGEN IN MIXED FERTILlZERS. as follows: Six Io-gram samples on watch glasses, BY S. S. PECK. and twenty-eight 2 . j-gram samples on paraffined Received September 5 . 1 9 1 1 At the 25th annual convention of the Association paper, on watch glasses, half of each lot containing of Official Agricultural Chemists, the referee on the the potash as sulphate and half as muriate. The determination of nitrogen devoted his report t o the weights of all being recorded, one each bf the IOdetermination of nitrogen in mixtures containing gram and two each of the a.5-gram lots were analyzed nitrate of soda. I n neglecting the instructions of a t once. The remainder were set aside for various intervals of time, being covered with large beakers 1906, he apologized by saying:’ “Another phase of the nitrogen .question considered so as t o prevent contamination by dust or insects, last year and discussed in correspondence with the but not hindering the free entrance of air. A further National Fertilizer Association seemed t o outweigh portion of each series was used for the determination in importance and urgency all others, namely, the of moisture according t o the official method. The 2.5-gram samples were analyzed a t intervals determination of total nitrogen in mixed fertilizers to which nitrate of soda is added.” In accordance by the modified Gunning method with the addition with his instructions a number of determinations were of 0.7 gram of mercury. A remarkable irregularity made b y the modified Gunning and Kjeldahl methods was obtained in our nitrogen figures, which we were of mixtures, in which the source of nitrate was a finally able to trace to the imperfect manner in which solution of nitric acid, accurately standardized. The the samples on the paraffined papers were covered results of the different analysts showed wide varia- by the salicylic-sulphuric acid mixture. A second tions, in the words of the author “mostly impos- set of determinations was started, with more regular sible.” I t seems very probable that the divergences results. The final figures in both sets, however, were due to the heat generated by the acid and water, lead to the same conclusions. The ten-gram samples were analyzed as follows: and Trescot expressed in his report to the referee The sample was washed into a beaker and stirred his conviction that on dry samples, the modified in water for about an hour. It was then filtered Gunning method gives correct results. onto a S. & S. paper, the nitrogen in a similar lot of I n the Hawaiian Islands, about 40,000 tons of ferwhich having been previously determined and found tilizer are used annually, a large proportion of which to be negligible in quantity. The entire sample ,consists of high-grade mixtures containing from ‘8 t o I O per cent. of nitrogen from ammonium sulphate, having been transferred t o the paper, it was washed nitrate of soda, and organic sources, principally until the entire leadings amounted to 500 cc. The blood or tankage. The reliability of the modified residue was then dried a t a low temperature, and digested with mercury, sulphuric acid, and sulphate Gunning or Kjeldahl methods is therefore of parof potash. The nitrogen constituted the residual ticular interest to both the fertilizer companies suporganic nitrogen. plying the material and this Experiment Station, Twenty-five cc. portion of the leadings were rewhere samples of a greater part of the shipments t o the. plantations are analyzed. In the latter part of spectively distilled with caustic soda for ammonia last year, complaints were received from a fertilizer nitrogen, and reduced with iron and sulphuric acid company that even when the utmost care was observed for the citric and ammonia nitrogen, according to A like quantity was pipetted in compounding mixtures containing nitrate, ammonia, the Ulsch-Strwt method. into a 500 cc. I
