712 EXPERIMENT STATION RECORD. [Vul.41 



table is friven showing the percentage of nitrogen ni zi samples of oil as deter- 

 mined by this volumetric process and by the Kjeldahl method. 



The presence of nitrogen in the petroleum of all the principal oil fields is 

 thought to furnish sufficient proof of the organic origin of these oils. 



Eegeneration of Nessler's solution, D. Pullman (Analyst, 44 (1919), No. 

 517, pp. 12Jf, 125). — A method of regenerating Nessler's solution is described, 

 which consists in recovering all the mercury and iodin of the solution by pre- 

 cipitation with a solution of a mercuric salt in amount equivalent to the 

 mercury present, and using the mercuric iodid thus formed in the preparation 

 of the Nessler's solution as follows: 



A hot suspension of 431 gm. of the mercuric iodid in 500 cc. of water is 

 treated with 31 gm. of zinc and the mixture stirred and heated for 5 minutes, 

 after wliich the hot solution of zinc mercuric iodid is filtered, the precipitated 

 mercury washed with boiling water, and the total filtrate made up to about 

 3.000 cc. with warm water. To this, after cooling, a saturated solution of 

 mercuric chlorid is added, a few cubic centimeters at a time, until a distinct 

 permanent red precipitate is formed. Then 540 gm, of sodium hydrosid, 

 dissolved in about a liter of water, is stirred in quickly, and the volume made 

 up to 5 liters. It is said that the best results are obtained with this solution 

 by adding about 3 cc. to every ,50 cc. of liquid to be nesslerized. 



The cause of and remedy for certain inaccuracies in Hausmann's nitregeu 

 distribution method, S. L. Jodidi and S. C. Moulton (Jour. Amer. Chem. Soc, 

 41 (1919), No. 10, pp. 1526-1531). — To determine the sources of error in Haus- 

 mann's nitrogen distribution method a series of experiments, conducted at 

 the Bureau of Plant Industry, U. S. Department of Agriculture, is reported 

 in which the nitrogen distribution in casein was determined by the method 

 as modified by Osborne and Harris (E. S. R., 15, p. 221), with the exception 

 that varying amounts of magnesium oxid were employed. 



It was found that the proportion of acid amid nitrogen was constant, and 

 did not depend upon the amount of magnesium oxid employed in the distilla- 

 tion. The proportion of nitrogen found in the magnesium oxid precipitate 

 was higher, and that of diamino and monamino nitrogen correspondingly 

 lower, the greater the quantity of magnesium oxid employed in the distillation. 

 These results were also corroborated in a study of the nitrogen distribution 

 in spinach. 



The authors conclude that " in order to obtain uniform results and a mini- 

 mum of ' humin ' nitrogen it is necessary to use the least possible amount of 

 magnesia which is sufliciont to render the substance to be distilled alkaline. 

 In the case of plant and animal materials the uniform application of 1 gm. 

 of magnesium oxid seems to be sati.sfactory, while in the case of proteins 0.5 gm. 

 suffices." 



The modified Benedict method for the estimation of sulphur in feeds, feces, 

 and foods, .T. O. Halvebson (Jour. Amer. Chcm. Soc, 1^1 (1919), No. 10, pp. 

 I494-I503). — The author, at the Ohio Experiment Station, has modified the 

 Wolf and Osterberg procedure (E. S. R., 24, p. 609) for the estimation of the 

 total sulphur in solid organic matter by a simplified technique, which requires 

 much less attention than the original method. The principal change in the 

 process consists in digesting the material on the steam bath to almost complete 

 solution with a diluted fuming nitric acid instead of lieating with the fuming 

 acid alone. The modified technique is as follows: 



About 3.44 gm. of feces or 2.7476 gm. of feeds is weighed out on half a 

 filter paper, which is then rolled up and put into a 300 cc. Kjeldahl flask. 

 Ten or 15 cc. of hot water is added, the flask rotated occasionally (preferably 



