1920] AGRICULTURAL CHEMISTRY — AGROTECHNY. 613 



table is roc-kctl by iiieaus of tbe adjustable arm L and crank M attac-hetl 

 by gears and pulleys to a (•(instant source of power. The electrode N is a 

 rectangular pit^-e of sheet platinum l.li by 2.4 cm., with pieces of platinum 

 wire welded to each end, and is prepared by plating as a cathode in a 1 

 per cent solution of platinic chlorid containing a small amount of lead 

 acetate to cause the platinum block to adhere. 



In operation the cell is partly filled with soil and solution, the table oscil- 

 late<l, and hydrogen run in for four or five minutes, the tube G is closed and 

 rocking at a rate of 72 complete oscillations per minute through an angle of 

 G to 7° continued for four minutes, hydrogen is again run in for four minutes, 

 and finally the tube G is again closed, the stoix-ock B opened, and readings are 

 taken immediately. 



The results of the investigation of several widely differing soils under the 

 conditions noted above are summarized as follows : 



" When an acid soil is added to a neutral salt solution the H-ion concen- 

 tration of the .solution reaches a maximum almo.st inmiediately if the soil is 

 wet thoroughly by the solution, but secondary reactions later cause a decrease 

 in U-ion concentration of the solution. 



"When an acid soil is added to a neutral salt solution containing a free 

 base the base is neutralized rapidly, as indicated by the change in H-ion con- 

 centration of the solution, following closely the law for equilibrium reactions, 

 but the H-ion concentration of the solution continues to rise for an unkuown 

 period. There is no sharp break in the progress of base absorption by an 

 acid soil which will warrant any arbitrary division, such as active and latent 

 acidity, or immediate and eventual lime requirement. 



"The changes in log C^ approach nearly straight line functions with pro- 

 gressive addition of base in the presence of a neutral salt solution. Different 

 indicators will give differences in lime requirement for s(nls depending uix>n 

 the slope of the log C" curve. The greatest differences may be expected 

 with soils high in organic matter. . . . 



" When a base is added to an acid soil comparatively insoluble products are 

 formed. Calcium produces a product less soluble than does potassium. The 

 specific conductance of a water solution of an acid soil to which a base has 

 been added increases with each addition of base, but the increase is greater 

 with potassium than with calcium hydroxid, which is far too great to be 

 accounted for by the difference in conductivity of potassium and calcium. 

 Calcium and potassium hydroxids have practically equivalent power to neu- 

 tralize the acid of an acid soil. The specific conductivity of a pure water solu- 

 tion containing a base in contact with an acid soil decreases with time. An 

 acid soil shows high reserve acidity. The reaction between a water solution of 

 a base and an acid soil is much slower than in the presence of a neutral salt. 

 The absorption of bases by acid soils is due largely to relatively insoluble 

 acids." 



Determination of borax in fertilizers and crude stock, C. H. Jones and 

 G. F. Andekson (Amer. Fert., 52 (1920), No. 8, pp. 57, 5S).— The authors, at the 

 Vermont Experiment Station, describe a method for the determination of borax 

 In fertilizers. This method is similar in principle to the method described by 

 Ross and Deemer (E. S. R., 42, p. 313), but differs from it in certain details, 

 particularly in that the evaporation, a-shing, and subsi^quent titration are on 

 1 gm. of material and that n/50 alkali is used in the titration in place of a 

 n/10 solution. These changes are considered to render the determination more 

 rapid and more accurate. 



Turbidity standard of water analysis, P. V. Wells (U. S. Dept. Com., Bur. 

 Standards Set. Paper 367 {1920), pp. 693-721, pi. 1, figs. 2).— This paper reports 



