524 EXPERIMENT STATION EECORD. 



from this source; and a discussion of future possibilities in commercial pro- 

 duction of nitrogenous plant food. 



Experiments with, feldspathic rock as a source of potassium, B. L. Hakt- 

 WELL and F. It. I»embi;r { Rhode Island Sta. Bui. 129, pi). 191-206, pi. 1) . — This 

 bulletin refers to experiments by this Department on finely ground feldsi)athic 

 rocks as a source of potash for plants and reports water cultures with wheat 

 seedlings in which varying amounts of fine ground feldspar were used alone or 

 in combinatiou with potassium chlorid and ground quartz, together with pot 

 experiments with wheat in w^hich fine ground feldspar and sulphate of potash 

 were compared in varying amounts. 



It was found in the water cultures that the addition of feldspar and of quartz 

 to 32 parts per million of potassium in form of potassium chlorid increased the 

 green weight of plants, the quartz being practically as efficient in this respect as 

 feldspar. There was no evidence that this increase was due to the potash of 

 the feldspar. 



In the pot experiments feldspar was apparently unable to supply the de- 

 ficiency of potash in a soil very poor in this element. " The maximaim increase 

 with the feldspar was only 18 per cent, whereas the maximum application of 

 sulphate of potash increased the yield about one and one-half times, or 148 

 per cent. 



"An average of the results from the three different applications reveals the 

 fact that, even though 5.5 times as much ground feldspar as sulphate of potash 

 was used, in order to supply an equal amount of potassium, the yield was in- 

 • creased ten times as much with the sulphate of potash as with the feldspar. 

 From the standpoint of crop production, then, the sulphate of potash was in 

 this case 55 times more valuable than an equal amount of ground feldspar." 



Investigations on the formation of oceanic salt deposits, J. H. Van't Hoff 

 {Sitzber. K. Preuss. Akad. Wiss., 190S, No. 22, pp. 436-1,39).— This is the con- 

 clusion of this series of contributions, and explains a cooperative plan for 

 scientific study of the German potash deposits. 



Contribution to the knowledge of the natural factors involved in the solu- 

 tion of tricalcium phosphate in the soil, R. Perotti (Atti R. Accad. Lincei. 

 Rend. CI. ScL Fis., Mat. e Nat., 5. ser., 11 {1908), /, No. 7, pp. US-451, fig. 1; 

 Rend. 8oc. Chim. Roma, 6 (1908), No. 1,, pp. 6^, 65; ahs. in Ghent. ZcntU., 

 1908, I, No. 22, p. 19^5; Jour. Chem. Soc. [London'\, 91, (1908), No. 5 ',8, II, 

 p. 521 ; Jour. Soc. Chem. Indus., 21 {1908), No. 13, p. 696).— From experiments 

 with different soil organisms in culture media using various sources of 

 nitrogen — ammonium tartrate and sulphate, potassium nitrate, urea, and 

 asparagin — the author concludes that in media containing physiologically acid 

 salts, as, for example, ammonium sulphate, there is a uniformly important 

 solution of tricalcium phosphate, while this action is insignificant in media 

 containing physiologically alkaline salts, such as sodium nitrate. 



Tests of the use of gypsum as a fertilizer, C. Dusserre {Ann. Agr. Suisse, 

 9 {1908), No. 1, pp. 1-9). — Tests of the effect of gypsum on the yield of pota- 

 toes, beets, oats, and wheat are reported, showing that in case of potatoes and 

 beets the api)lication of gypsum greatly increased the yield. In case of pota- 

 toes the mineral matter and starch were also considerably increased by the 

 use of gypsum. In case of sugar beets the proportion of lime and potash in 

 the ash was slightly increased on the gypsum plats. 



In laboratory experiments it was found that the mixture of gypsum with 

 soil resulted in a considerable increase in the amount of potash extracted by 

 pure water. If the amount of potash extracted by pure water from untreated 

 soil be taken as 100, that extracted from soil containing gypsum was 127, from 



