844 EXPERIMENT STATION RECORD. 



Loss of nitrogen in putrefying peptone solutions. Bacteriological soil 

 investigation, P. Eiirenberg (Coif hi. Bakt. [etc.] 2. AM., 15 (1905), A T o. J/-6, 

 pp. 154-164; abs. in -lour. Chem. Soc. [London], 88 (1905), No. 517, II, p. 750).— 

 The author calls attention to the fact that in determining the power of soils 

 to produce putrefaction in peptone solutions it is necessary to make determina- 

 tions with the whole contents of the flasks, thus avoiding filtration and the use 

 of aliquot portions of the solution. The putrefying power of similar soils 

 varies appreciably under different treatments. The loss of nitrogen occurring in 

 putrefying peptone solutions inoculated with soil and then filtered is ascribed 

 to absorption rather than biological fixation in the soil. 



The absorptive power of soils for bone and mineral superphosphates, C. 

 Montanaei {(linn. Ztg., 29 (19<i5), No. 75, pp. 988, 989; alts, in Jour. Chan, 

 soc | London], 88 (1905), No. 517, II, p. 759). — The author briefly reports ex- 

 periments carried out on kilogram lots of soils of different kinds treated in 

 funnels with solutions of the different superphosphates, which indicate that the 

 popular belief as to the greater activity of bone superphosphate is not supported 

 by the facts. Apparently, however, the phosphoric acid of the mineral super- 

 phosphate was not quite so rapidly absorbed by the soils, although it is the 

 author's opinion that the portion absorbed was more rapidly taken up by the 

 plant roots. 



On the effect of liming upon certain constituents of a soil, B. L. Hartwell 

 and J. W. Kellogg (Rhode Island Sta. Rpt. 1905, pp. 242-252).— ll Since 189?, 

 two of the permanent experimental plats upon the station plain have received 

 equal amounts of nitrogen annually in sulphate of ammonia, and two others in 

 nitrate of soda. About 3.7 tons of air-slaked lime have been applied in all to 

 one of the plats receiving sulphate of ammonia and to one of those receiving 

 nitrate of soda. Equal amounts of muriate of potash and dissolved boneblack 

 have been added annually to each plat." 



Chemical studies of the influence of this treatment on the humus content and 

 the composition (ash constituents) of the humus of the soil show that "the 

 amount of humus is now less in the limed than in the unlimed plats. The 

 amount of free humus is likewise less in the limed plats. A smaller part of the 

 humus is present as free humus in the limed plats. The loss by igniting the 

 oven-dry soil was somewhat less from the samples of the limed plats than from 

 the unlimed ones. 



" The total nitrogen in the limed plat to which nitrate of soda is applied is 

 less than the amount common to the other three plats. 



" In the case of the unlimed plats the one to which sulphate of ammonia has 

 been added would require much more lime to neutralize it, according to the lime- 

 water test, than the one which has received nitrate of soda. Upon the same 

 basis, no further application of lime would be required for the limed plat to 

 which nitrate of soda has been added, although the limed plat receiving sul- 

 phate of ammonia is still somewhat acid. 



" Most of the ash left upon destroying the separated humus and free humus 

 by ignition is composed of iron and aluminum oxids, phosphoric acid, and silica. 



" In the case of the ash remaining from the free humus, that from the limed 

 soils contained larger percentages of phosphoric acid and smaller percentages 

 of silica than that from the unlimed soils. 



" Surprisingly large amounts of iron were found in the ash left from the 

 ignition of the humus and free humus. The iron in the ammoniacal solutions 

 of humus could not be thrown out by certain of the ordinary precipitants. 



"An artificial product made by precipitating the humus from an ammoniacal 

 extract of leaf mold, by means of ferrous chlorid, contained in its oven-dry 

 condition II per cent of ash, of which 83 per cent was ferric oxid, the remainder 

 being phosphoric acid and silica." 



