SOILS FERTILIZERS. 715 



The percentage of nitrogen in the crop was greater with the mineral sources 

 of nitrogen (including lime nitrogen) than with the organic sources. 



The utilization of the nitrogen of the air by means of the electric flame, 

 J. Zenneck {Phys. Ztschr., 11 {1910), No. 26, pp. 1228-1233, pis. 4; Naturw. 

 Rundschau, 26 {1911), Nos. 6, pp. 69-11, figs. 4; 7, pp. 81-83, figs. 2; abs. in 

 Metallurg., and Cliem. Engin., 9 {1911), No. 2, pp. 73-75, figs. 7 ; Cliem. Ztg., SJf 

 {1910), No. 114, P' iOU). — This is a paper presented at the meeting of the 

 German Naturalists and Phj-sicians in Konigsberg, describing various forms of 

 electric furnaces which have been used in the manufacture of nitrogen com- 

 pounds from the air. 



Zeolitic potash fertilizers, T. Remy {Mitt. Deut. Landiv. Gesell., 25 {1910), 

 No. 52, pp. 777-77.9, figs. 3). — The author reports data indicating a higher 

 efficiency of lime trass fertilizer as a source of potash for potatoes than Stutzer 

 found for peas and barley (E. S. R., 24, p. 134). The material used in these 

 experiments contained water-soluble potash 7.63 per cent and total potash 9.34 

 per cent. Stutzer experimented with a material containing only 2.41 per cent of 

 difficultly soluble potash. 



Zeolitic potash fertilizers, A. Stutzer {Mitt. Deut. Landw. Gesell., 26 

 {1911), No. 2, p. 21). — The author suggests that the better results obtained by 

 Remy (noted above) were due to the added potash salts in the reinforced 

 trass fertilizer used in his later experiments. 



Increased German production of potash, F. D. Hill {Daily Cons, and Trade 

 Rpts. \_U. 8.], 14 {1911), No. 21, p. 329).— Statistics are given which show 

 that under the new apportionment the amount of potash which may be produced 

 during the period from May 1 to December 31, 1911, is 219,780 metric tons of 

 pure potash (K2O) for home consumption and 282,590 tons for exportation, 

 an increase of about 100,000 tons over the previous apportionment. 



A review of the phosphate fields of Florida, W. H. Waggaman ( U. 8. Dept. 

 Agr., Bur. Soils Bui. 76, pp. 23).— This bulletin reports work in cooperation 

 with the U. S. Geological Survey. The results of the inquiry are summarized 

 as follows : 



" There are two commercially important classes of phosphate rocli in Flor- 

 ida — the hard-rock phosphate and the land-pebble phosphate. 



" The hard-fock phosphate fields extend north and south along the west coast 

 of the peninsula for a distance of 100 miles. The present land-pebble phos- 

 phate regions lie south of the hard-rock fields, in Polk and Hillsboro counties. 



" Both the bard-rock and pebble deposits of phosphate belong to the Ter- 

 tiary period. The methods of mining these two classes of phosphate rock 

 differ cbnsidergjbly. In the hard-rock workings the material is either dug out 

 or dredged. In the pebble deposits hydraulic mining is employed. 



" Practically all the hard-rock phosphate is shipped abroad and sold on a 

 guaranty of 77 per cent tricalcium phosphate. The pebble phosphate is used 

 both in this country and abroad, being sold on guaranties ranging from 60 to 75 

 per cent tricalcium phosphate. 



" In order to remove the impurities the material which comes from the mines 

 is put through a washing process, during which much valuable phosphate is 

 washed away. It is estimated that the actual amount of phosphoric acid lost 

 in preparing the rock for the market is nearly twice as great as the quantity 

 saved. 



" Possible means of utilizing this waste material are suggested, namely, to 

 apply it to muck soils deficient in phosphoric minerals or to extract the phos- 

 phoric acid from it by means of a cheap solvent. 



" The average cost of preparing hard-rock phosphate for the market is not 

 less than $3.50 per ton, while the finished pebble product costs about $2 per ton. 



