1917] SOILS FERTILIZERS. 427 



observed. When the supply of available phosphoric acid in the soil was low, 

 and also when the total supply of phosphoric acid was low, an effect of double 

 superphosphate could be expected. While the experiments on the lighter soils 

 showed no action, those on the heavier soils showed a distinct action of double 

 superphosphate. 



It is concluded that for these .soils there is a distinct limit for phosphate 

 content. Whenever the total content was less than 0.026 per cent or the 

 available content less than 0.009 per cent, an effect of fertilizing with super- 

 phosphate could be expected, and in some cases also where only one, more 

 particularly the available phosphorus, was less than these limits. It is 

 further concluded that an analysis of soil is not sufficient to determine the 

 need for fertilization with double superphosphate. Fertilization with double 

 superphosphate did not hasten ripening. 



The extraction of potash from silicate rocks, II, W. H. Ross {Jour. Indus, 

 and Engin. Chem., 9 (1911), No. 5, pp. 467-472, fig. 1; abs. in Amer. Jour. Set., 

 4. ser., 43 {1917), No. 258, p. 485).— A study of the various methods, now in- 

 cluding over 100 patented processes, that have been proposed for the extraction 

 of potash from feldspar is reported in continuation of work previously noted 

 (E. S. R., 27, p. 628). 



It is concluded that the economic success of any process depends upon the 

 recovery at the same time of some other product of value in addition to potash, 

 the most promising by-product being cement. In experiments in which feldspar 

 was subjected to the action of water at high temperature and pressure, there 

 was no decomposition. When, however, the powdered feldspar was digested 

 with water containing 1.7 parts lime at a steam pressure of from 10 to 15 

 atmospheres, about 90 per cent of the potash went into solution in the form of 

 hydroxid and the residue had the composition required for Portland cement 

 clinker. 



Potash from. Canadian feldspar, D. J. BenhaM {Canad. Chem. Jour., 1 

 {1917), No. 1. pp. 8-11). — The author describes a process for the extraction of 

 potash from Canadian feldspar which it is claimed yields muriate which is 

 almost chemically pure and permits the collection of at least 87 per cent of 

 all the potassium chlorid vapors released from a raw mixture containing from 

 9.5 to 12.5 per cent of potash. " The prbcess . . . consists in heating to a 

 high temperature in a blast furnace 110 tons of a mixture of feldspar, coal, 

 calcium, chlorid, and limestone. The limestone is used to render the slag fluid, 

 while the chlorin of the calcium chlorid combines with the potash, forming 

 potassium chlorid which distills over at the temperature of the blast furnace 

 into a condenser, where it meets a current of steam in which it dissolves. By 

 a process of evaporation and crystallization of the solution thus obtained, the 

 salt is obtained in a high state of purity." 



Report on wood and plant ashes as a source of potash, R. A. Beeey {West 

 of Scot. Agr. Col. Bui. 73 {1916), pp. I4I-I49) .—Analyses showing the potash 

 content of the ashes of bracken, spruce, forest hardwoods, flue dust, and mis- 

 cellaneous organic substances are reported and discussed. 



Bracken was found to contain 20.45 per cent of potash soluble in strong 

 hydrochloric acid. Flue dust from blast furnaces was poor in potash, con- 

 taining under 4 per cent. Spruce and forest hardwood ashes contained 11.94 

 and 11.79 per cent, respectively, of potash soluble in strong hydrochloric acid. 



[Liming and manurial experiments] {Ann. Rpt. Agr. Expt. Stas. Assam, 

 1916, pp. 26-38). — This is a progress report of miscellaneous liming and 

 manurial experiments. On an old alluvial soil it was found that annual dress- 

 ings of wood ashes will replace the more expensive lime as a soil ameliorant. 



