334 EXPERIMENT STATION RECORD. 



fell drop by drop into a £ to 1 per cent solution of hydrochloric acid, 

 where it was precipitated in flakes and settled at the bottom of the ves- 

 sel. The hninic acid was transferred to a folded Alter and washed first 

 with 0.25 to 0.5 per cent hydrochloric acid and then with distdled 

 water. The washed humic acid was mixed first with chalk and then 

 with white quartz sand, which had been treated with aqua regia and 

 washed with distilled water. 



Three series of experiments were carried out, (1) with soil treated 

 with 3 per cent hydrochloric acid in 13 pots planted to barley, oats, 

 lupines, and peas; (2) with soil treated with a 1 per cent solution of 

 hydrochloric acid in 4 pots planted to barley, and (3) with calcium 

 humate in 8 pots planted to barley and peas. 



The chief results obtained may be summed up as follows: 



(1) The chernozem soil treated with a 3 per cent solution of hydro- 

 chloric acid and inoculated with the micro-organisms of the soil con- 

 tains easily assimilable nitrogen and phosphorus in quantities sufficient 

 for the formation of the vegetative organs of barley. 



(2) Calcium humate containing no mineral admixtures may be 

 obtained by mixing gelatinous humic acid with calcium carbonate, 

 which is decomposed under these conditions with the evolution of car- 

 bon dioxid. 



(3) The humic acids extracted from the chernozem by successive 

 treatment with acid and alkali, even when in the form of calcium salts, 

 disturb the regular development of plants, causing an intensified for- 

 mation of shoots and rendering impossible the formation of the repro- 

 ductive organs. 



(4) Potassium phosphate renders the poisonous properties of the 

 artificially obtained calcium humates more marked. 



(5) The poisonous action of the calcium humates is probably due to 

 the presence of ferrous oxid in the humus substances formed by the 

 reduction of the ferric oxid during the process of the extraction of the 

 humic acids. 



(G) The opinion of Hoppe-Seyler that the humus substances are 

 unalterable under the ordinary conditions of the soil and in no measure 

 serve as food for the lower organisms is erroneous. The humus sub- 

 stances extracted from the chernozem by chemical means either in sol- 

 uble form or insoluble form, when acid in reaction as well as when 

 feebly alkaline or neutral, in the presence as well as in the absence of 

 air, are a very suitable nutritive medium for the growth of the lower 

 organisms. 



(7) The phosphorus and, apparently, the nitrogen of calcium humate 

 in the presence of the micro-organisms of the soil contribute to the 

 growth of the higher plants (barley).— p. fireman. 



Review of the literature of soils, L. Ociiapovski (Selsk. Khoz. % Lyesov., 190 

 (1S9S), July, pp. 147-1SG). 



Soil bacteria in their relation to agriculture, I, F. D. Chester {Delaware Sta. 

 Bui. 40, pp. 10, fujs. ;?). — This is a popular summary of information on this subject. 



