SOILS FERTILIZERS. 425 



It is stated that these deposits consist of mineral eartliy phosphorites whose 

 physical characteristics vary, depending roughly on the relative proportion of 

 calcium phosphate and impurities. The phosphates are of three distinct types, 

 namely, rock phosphate, pebble phosphate, and soft phosphate which occurs in 

 fine powder or in soft masses. These phosphates occur in sedimentary rocks and, 

 with the exception of certain deposits southwest of Lakeland, are of secondary 

 origin, having been redeposited either by mechanical or chemical action. It is 

 stated that phosphate appears to be very widely distributed in the northern and 

 central parts of the peninsula and deposits are found on the west side of 

 Apalachicola River in western Florida. The workable areas are, however, con- 

 fined to certain parts of the peninsula. 



Analyses of the different types of phosphate are reported, which indicate 

 that the average content of tricalcium phosphate in land pebble phosphate ranges 

 from about 65 to 75 per cent and in river pebble phosphate from 55 to 65 per 

 cent. Composite samples of rock phosphate showed in one case over 82 per cent 

 tricalcium phosphate and in other cases contents of tricalcium phosphate vary- 

 ing from 75.3 up to 81.06 per cent. 



A bibliography of works on Florida phosphates is appended. 



Potash from wood and plant ashes, H. Bradley {MctaUurg. and Chem. 

 Engin., 13 {1915), No. l.'t, pp. 841-846, fig. 1). — This article deals with the his- 

 tory of potash production from wood ashes, with the different uses of potash, and 

 with the process of manufacturing potash from wood ashes and possible im- 

 provements therein. The characteristics of potash from wood ashes and its 

 practical utilization are also discussed. Tables of analyses of potashes from 

 wood and of various woods and their ashes are included. 



Potash in certain copper and gold ores, compiled by B. S. Butler (f7. S. 

 Geol. Survcu Bui. 620-J {1915), pp. 227-236) .—This paper contains portions of 

 complete analyses of copper and gold ores from different districts which show 

 that the potash content is in most cases relatively high. 



Experiments on potash extraction from muscovite, by G. Steiger, are also 

 reported which show that the muscovite used contained 9.55 per cent of potash. 

 " Of this amount practically the whole was found in the leach water, showing 

 that by first fusing the muscovite and then treating it with ammonium chlorid 

 its potassium was entirely converted into the soluble form. The results show 

 that more than 25 per cent of the potassium present may be converted into 

 the soluble form by the treatment with ammonium chlorid alone." It was also 

 found that "by a very superficial treatment with hydrochloric acid approxi- 

 mately one-third of the potassium may be extracted." 



Evaporation of potash brines, W. B. Hicks ( U. <S'. Geol. Swvey, Prof. Paper 

 95-E {1915), pp. 65-72, figs. S). — In evaporation studies on artificial potash 

 brines, the purpose of which was to throw light on the conditions governing 

 the deposition of potash salts from solution, it was found that the potassium 

 was concentrated best in brines containing carbonates and chlorids and poorest 

 in those containing sulphates and carbonates, although a small amount of sul- 

 phate apparently did not hinder the concentration materially. 



" In brines that contain several acid radicles the concentration of potassium 

 may increase to a maximum as evaporation proceeds and then decline. The 

 evidence at hand indicates that a large percentage of the potassium in a solu- 

 tion is lost during evaporation before the maximum concentration of potassium 

 is attained. The loss is small until the potassium reaches a concentration of 

 about 4 per cent, but it is very rapid during further evaporation. Therefore, 

 in the commercial extraction of potash from brines, especially those of the 

 alkalis, it would seem best first to concentrate the solution by evaporation until 



