520 EXPERIMENT STATION RECORD. 



A glass cylinder with a parchment bottom is suspended in a second and larger 

 glass cylinder. One platinum electrode (cathode) is placed above and the 

 other (anode) below the parchment membrane, with the soil between them in 

 the small cylinder. The soil is first well mixed with distilled water and then 

 washed into the small cylinder, in which the water level is brought to a height 

 of 4 cm. above the soil and to the same level in the larger cylinder. The cur- 

 rent is so regulated as not to exceed a strength of 3 amperes, and is allowed to 

 flow until the water reaches a temperature of 50° C. The effect of the current 

 is to produce an inward flow of the alkaline solution to the cathode, with ac- 

 companying precipitation of the colloid substances. The humus acids pass 

 through the parchment membrane to the anode and there form a brown colored 

 solution. In this way a separation of alkaline and acid solutions is effected, 

 and these may be drawn off, fresh water added, and the operation repeated 

 until there is no further action by the current. It was found, however, that 

 one treatment with the electric current gave amounts of soluble material, espe- 

 cially potash, closely agreeing with those obtained by treatment with steam or 

 oxidation by hydrogen peroxid. and is believed to furnish a reliable method of 

 determining the easily soluble plant food in soils. 



Only in case of potash was there close agreement between the amounts of 

 mineral matter taken up by plants and that yielded by the three methods of 

 solution. The amounts of potash yielded by oxidation and by treatment with 

 steam were almost identical with those taken up by the plant in all of the 

 soils tested. The single electrical treatment gave results slightly higher than 

 the other two methods. When the electrical treatment was continued until no 

 further action was produced twice as much potash was dissolved as when the 

 soil was subjected to the single electrical treatment. 



In case of phosphoric acid the relations between amounts dissolved and taken 

 up by crops were not very close. In general, treatment with steam and a 

 single treatment with the electric current yielded 2 to 5 times the amount 

 assimilated by plants. In case of lime the relationships were still more in- 

 definite. 



The treatment of soils with a strong constant electric current, J. Konig, 

 J. Hasenbaumeb, and C. Hassler (Ztschr. Angew. Chem., 2.'t {1911), No. 49, pp. 

 23.'il-23Jt8, fig. 1; abs. in Jour. Soc. Chem. Indus., 31 (1912), No. 2, p. 83). — An 

 account of these investigations is included in the article noted above. 



Bacteria of frozen soil, II, H. J. Conn (Centhl. Bakt. [etc.}, 2. AM., 32 

 (1911). No. 3-5. pp. 70-97, figs. 7). — Further investigations on this subject con- 

 firm the conclusions of a previous article (E. S. R., 24, p. 529) that bacteria 

 actually multiply in frozen soil. The increase during the winter was, however, 

 almost wholly in one group, many of the most vigorous summer bacteria dis- 

 appearing during the cold weather. 



The results indicate that the increase in frozen soil is due not to the favoring 

 influence of cold weather, but to its repressing effect on the rivals of that 

 group of bacteria which is capable, when unhindered, of making the greatest 

 growth. 



The present status of soil inoculation, K. F. Kellerman (AJ)s. in Science, 

 n. ser., 35 (1912), No. 893, pp. 228, 229).— The following is an abstract of a 

 paper presented at the Washington meeting of the Society of American Bac- 

 teriologist? in December, 1911 : 



" The method of pure-culture inoculation is less certain than the use of soil 

 from old well-inoculated fields, but has, however, the advantage of cheapness 

 and greater ease of ti'ansportation and application, as well as the important 

 advantage of the absence of introducing weeds and plant diseases. . . . 



