428 EXPERIMENT STATION RECORD. [Vol. 43 



The fertilizing ralue of the reverted phosphoric acid in superphosi)hate, 



E. IIasklhoff (Fuhlincfs L(tndu\ Ztg., 68 {1DJ9), No. 23-2.',, pp. 4.50-.',60).~ 

 Experiments on the fertilizing value of reverted superphosphate are reported. 

 These showed that the value of the reverted citrate-soluble phosphoric acid in 

 superpliosphate is less than 70 per cent of the water-soluble phosphoric acid. 

 It is concluded that in general there is, under normal conditions of cultivation 

 in mineral soils, no comparison between the two. 



The potash salt beds of Dallol (Eritrea), M. Giua (GV/^. Chim. Ital., 48 

 (1918), II, No. 1-2, pp. 1-8). — The potash beds occurring in Italian Eritrea 

 are described and analyses of 32 samples reported, showing a potassium 

 chlorid content in 31 samples varying from 23 to 98.6 per cent. Some of the 

 samples contained considerable sodium chlorid. 



The status of lime in soil inii>rovenient, E. O. Fippin (Jour. Amer. Soc. 

 Agron., 12 (1920), No. 4, pp. 111-124). — A brief review of available information 

 on the use of lime on soils is given, showing the lack of reliable data on such 

 phases of the subject as the effect of lime upon soil, forms and fineness of lime, 

 and relation of form of lime to the type of soil. 



Home production of lime by the farmer, C. C. Fletcher {TJ. S. Dept. 

 Ayr. Yearhook, 1919, pp. 335-341, fi(j.s. 5). — Information is given on the grinding 

 or burning of limestone and other lime-containing materials for use on soil. 



[Commercial fertilizer analyses], J. L. Hirxs, C. H. Jones, G. F. Anderson, 

 and L. H. Flint {Vermont Sta. Bui 216 {1920), pp. 3-16).— A summary is 

 given of the analyses of 356 samples of fertilizers and fertilizer materials 

 representing 130 brands collected for inspection in Vermont during 1919. 



It is stated that as a whole the fertilizers were not up to their usual grade, 

 with particular reference to available nitrogen. Data are also included on the 

 cost of fertilizers in the State during 1919, showing that nitrogen in commercial 

 fertilizers cost between 53.4 and 97.6 cts. per lb. as against 30 cts., delivered, 

 for nitrogen in Government nitrate. 



Registration brands of fertilizer to August 1, 19 18 {Bid. N. C. Dept. 

 Ayr., 39 {1918), No. 7, pp. 93).— This bulletin contains a list of brands of fer- 

 tilizers registered for sale in North Carolina up to August 1, 191S, together 

 with guarantied analyses. 



AGRICULTUKAL BOTANY. 



Hydration and growth, D. T. IMacDougal {Carnegie Inst. irw-sZ/. Puly. 291 

 {1920). pp. yi+116, fig.^. 52). — The purpose of the present work was to study 

 growth upon the basis of a more inclusive conception than that usually iuTplied 

 in osmosis. The total absorbing capacity of a cell (as a mass of protoplasm) 

 for water is regarded as being exercised in the process of hydration, the source 

 of energy in growth and swelling being the unsatisfied attraction of molecules 

 or particles or ions bearing an electrical charge. Substances made up in this 

 manner may unite with definite pi'oportions of water, which becomes part of a 

 symmetrical chemical structure, the union being ordinarily termed hydration.' 

 In addition to this, however, it is known that such particles may adsorb and 

 hold in combination additional molecules of water, an action especially char- 

 acteristic of swelling in colloids, and the term hydration is used in the present 

 work to include the entire range of such action. 



In the method of study employed, biocolloids have been combined from pento- 

 sans and proteins in proportions sinmlating those occuring in plants. The 

 total range of swelling of this material in thin plates has been measured by 

 means of the auxograpli, developed for this purpose, and the series of measure- 



