1917] SOILS — FERTILIZERS. 321 



over night, the samples tested have all shown a precipitate. (2) When this 

 precipitate was filtered off and the filtrate dialyzed in a dialyzing tube in run- 

 ning water iintil it no longer showed a precipitate with BaCh, the filtrate did 

 not prove toxic to root hairs on Tradescantia cuttings placed in it. while con- 

 trols in bog water allowed only a very poor development of root hairs on cut- 

 tings of this species. (3) When 500 cc. of filtered bog water was distilled until 

 the residue was only 80 cc, the distillate was colorless and was not toxic to 

 root hairs on Tradescantia cuttings while the residue was much darker in 

 color than bog water and almost entirely inhibited the formation of root hairs 

 on these cuttings. (4) When saturated with (NH4);S04 and allowed to stand 

 over night, the above distillate gave no precipitate, while the residue gave a 

 much heavier precipitate than untreated bog water did. (5) All samples of 

 bog water tested were acid to litmus and to phenolphthalein. (6) The acidity 

 of the residue mentioned in (3) was greater than that of the untreated bog 

 water, while the acidity of the distillate was less than that of the untreated 

 bog water. The acidity was determined by neutralization with N/20 NaOH, 

 using phenolphthalein as an indicator. . . . The fact that the osmotic pres- 

 sure of bog water is very low suggests that the material in solution in it is 

 probably in a colloidal state. The data here given seem to confirm this view 

 and to warrant the suggestion that this colloidal matter is a large factor in 

 the toxicity of the water." 



A list of ten references to literature bearing on the subject is appended. 



Some factors influencing nitrogen fixation and nitrification, B. Williams 

 (Bot. Gas., 62 (1916), No. 4, pp. 311-317).— In continuation of work previously 

 reported (E. S. R., 33, p. 620), experiments conducted at the Virginia Experi- 

 ment Station on nitrogen fixation in garden soil and in various other soils 

 stored in the laboratory for periods of different lengths showed that the 

 nitrogen-fixing flora significantly decreased in its activity under the influence 

 of drying. This deterioration was manifested as early as two weeks after 

 removing the soil from the field and exposing it to the ordinary laboratory 

 conditions of drying. After 15 months, however, a number of soils retained an 

 ability to fix nitrogen, which is taken to indicate that some species at least have 

 considerable resistance to drying. A number of qualitative tests for Azoto- 

 bacter in soils kept in storage for 15 months indicated that this organism is 

 more easily attenuated than some other species. Further tests with three soils 

 ^vith low powers of fixation showed that the soil extract itself " probably does 

 not carry substances which would retard fixation." 



A continuation of studies on nitrification in soils of poor nitrifying power to 

 which sugar and lime were added showed that without the use of lime a number 

 of soils completely failed to nitrify ammonium sulphate, and few exhibited what 

 might be termed an average nitrifying power. Under the influence of lime there 

 was an increase of nitrifying power in the majority of the soils, although the 

 stimulation was not especially noteworthy. " It appears that where there is 

 some development of the nitrifying flora in the soil originally the effects of lime 

 are decidedly more evident than in those soils apparently devoid of nitrifying 

 power." 



There was no formation of nitrates whatever under the influence of 2 per cent 

 of mannite. It not only failed to afford a source of energy for the nitrifying 

 ferments, but exerteil a depressing effect on the activities of such as were 

 present. 



Production of alkali in soils by denitrification, R. Aladjem {Cairo Sci. 

 Jour., 8 (1914), No. 99, pp. 274-278). — Studies on the processes of nitrification 

 and denitrification in sandy loam soil and the conditions governing them are 

 reported. 



