842 EXPERIMENT STATION RECORD. 



(E. S. R., 16, p. 756), are reported. These show that the minerals in the soil 

 are identical with those of the original rock from which it was derived, the only 

 difference being that the crystals arc entire in case of the rock and broken in 

 case of the soil. 



Soil builders at work, S. W. Fletcher (Country Life A titer.. 9 {1906), No. 3, 

 pp. 325-327, figs. 18). — A popular discussion of the weathering of rocks; plants 

 and animals as soil builders; and the action of iee, wind, and micro-organisms. 

 Soil exhaustion as well as formation is considered. 



Feldspar and mica as sources of potash, D. N. Prianishnikov (Landw. Vers. 

 Stat., 63 < l!>').~>). No. 1-2, }>p. 151-156). — Sand cultures with tobacco, buckwheat, 

 flax, peas, sunflowers, and barley, in which these substances were used in fine- 

 ground condition (less than 0.25 mm. in diameter) in connection with sodium 

 nitrate, ammonium nitrate, ammonium sulphate, and calcium nitrate, are 

 reported. 



The results show that the orthoclase. even in large amounts, had very little 

 effect on the growth of plants, either alone or in association with the other 

 materials. Mica and apophyllite gave somewhat better results than the ortho- 

 clase. The associated salts therefore apparently did not exert the solvent effect 

 which had been previously noted in the case of phosphates j(E. S. R., 17, p. 538). 



Investigations on the insoluble potassium compounds contained in humic 

 substances, M. Berthelot (Compt. Rend. Acini. Sci. [Pari*], l',l (1905), No. 26, 

 l>l>. 1182-1181; aos, in Jour. Client. Soc. [London], 90 (1906). No. 520, II, 

 p. 117).— In continuation of previous investigations « the author studied the 

 double decomposition resulting from the action of the soluble alkaline salts of 

 weak acids, such as the acetates of potassium and calcium, on wood charcoal 

 exhausted of soluble compounds partly by treatment with pure water and partly 

 by extraction with dilute hydrochloric acid. 



The results indicate the presence in wood charcoal of compounds which in 

 general behave toward the salts of potassium and calcium named like the humic 

 acid artificially prepared from sugar. These compounds, however, are of two 

 classes of unequal stability, one immediately destroyed by dilute hydrochloric 

 acid, the other being more resistant to this reagent. The compounds are analo- 

 gous in their properties and affinities to different artificial and natural silicates. 



On the causes of unproductivity in a Rhode Island soil, H. J. Wheeler 

 and J. F. Breazeale (Rhode Island Sta. Rpt. 1905, pp. 286-323) . — This is an 

 account of cooperative investigations between the Rhode Island Station and the 

 Bureau of Soils of this Department, "to study the soluble toxic substances in 

 a highly unproductive soil and also in soils in good tilth and of high pro- 

 ductiveness." 



The influence of the treatment of the extracts of such soils with nonnutritive 

 solid materials and with certain soluble chemical substances (ferric hydrate, 

 carbon black, calcium carbonate and sulphate, sodium chlorid. potassium sul- 

 phate, disodium phosphate, sodium nitrate, and pyrogallol) was studied by 

 means of water cultures with wheat, both in the normal and treated extract. 

 The conclusions reached are that the unproductiveness of the infertile Miami 

 silt loam from the station farm is in some measure transmitted to the aqueous 

 extract of the soil. 



The beneficial effect of treatment of the extract with finely divided carbon 

 black and ferric hydrate is taken " to indicate that the extract contained inju- 

 rious bodies which were removed from or altered in the soil extract so as to 

 become noninjurious, or partially so, by the action of the solids above named. 

 Some evidence in the same direction is derived from the fact that treatment of 



« Compt. Rend. Acad. Sci. [Paris], 141 (1905), No. 21. p. 70S. 



