518 EXPERIMENT STATION RECORD. [Vol.37 



Fargo silt loam, Carrington silt loam, Hempstead silt loam, prairie covered 

 loess, and forest covered loess; and extracts of a sphagnum covered peat soluble 

 In (1) 1 per cent hydrochloric acid, (2) 4 per cent sodium hydroxid but pre- 

 cipitated by acid, and (3) 4 per cent sodium hydroxid and not precipitated by 

 hydrochloric acid. The following conclusions are drawn : 



" The figures for the ammonia nitrogen in a protein analysis are not appre- 

 ciably changed when the hydrolysis is carried out in the presence of an ignited 

 mineral soil equal to 20 times the weight of the protein material. The 

 ' humin ' nitrogen wa.s greatly increased by hydrolysis in the presence of 

 ignited mineral seil. The histidin fraction entirely disappeared. . . . The 

 analysis of a pure protein in the presence of an ignited mineral soil does not 

 give reliable results for the different fractions. Therefore, the figures obtainetl 

 for the nitrogen distribution in soils are of value only when used for purposes 

 of comparison. Such data should not be compared with analyses of pure 

 proteins. 



" Since practically all mineral soils give furfural on treatment with acid, it is 

 very likely that a very considerable amount of the total humin nitrogen found 

 is di>e to the presence of carbohydrates in the soil, which give rise to furfural 

 during hydrolysis. This may combine with certain of the nitrogenous com- 

 pounds and cause an increase in the humin nitrogen, as well as adsorb or 

 occlude nitrogenous compounds in the ' humin ' formed from furfural by po- 

 lymerization. 



" This investigation of the distribution of organic nitrogen in the soil has 

 indicated a new fraction which should be recorded separately. This is the 

 fraction of nitrogen removed from a colorless solution by calcium, iron, and 

 aluniinuni hydroxids on the addition of calcium hydroxid. The nitrogen 

 retained in this fraction must consist almost entirely of material of nonprotein 

 origin, since the organic substances in this precipitate have been shown to be 

 colorless organic coinpoinids adsorbed by or combined with the metallic hydrox- 

 ids. This fraction has been reported as nitrogen precipitated by calcium 

 hydroxid. 



" The true humin nitrogen remains In the residual soil after hydrolysis, but 

 In addition nonhundn nitrogenous compounds are al.so retaineil in this fraction. 

 The strength and volume of the hydrochloric acid used in hydrolysis has little 

 effect on the nitrogen distribution of the hydrolysate, provided acid as strong 

 as constant l)oiling acid is used, in the proportion of at least two parts of acid 

 to one of soil. Results gained from a study of different soils indicate that the 

 organic nitrogen dissolves during hydrolysis to almost the same extent regard- 

 less of the origin and nature of the soil. . . . 



•* In the comparison of the different extracts from sphagnum-covered peat 

 the portion soluble in sodium hydroxid and not precipitated by hydrochloric 

 acid gives a nitrogen distribution approximating very closely that of a normal 

 plant protein. The nitrogen dissolving in the preliminary hydrochloric acid 

 leaching shows a nitrogen distribution which is certainly not due exclusively to 

 protein materinls. e. g., an ammonia nitrogen percentage of 6r).4 and amino 

 nitrogen in the fdtrate from bases of 17.11 per cent. 



"The most significant fact brought out by this study is that the organic 

 nitrogen distribution in different soil types is very uniform. This is to be 

 expected, since it has been pointed out that the nitrogen distribution in soils is 

 an average distribution of all the plant and animal nitrogenous products that 

 find their way into the soil." 



Further studies of the nitric nitrogen content of the country rock, R. Stew- 

 art and W. Peteksox {I'tah Sfa. Bui. 150 (1911), pp. S-20. Jig. J).— The sub- 



