221 



region of Germany, but thus far this search has not resulted in 

 the discovery of any deposits of commercial importance, though 

 borings, in certain localities, are still being carried on by the 

 Geological Survey. The attention of the investigators has been 

 seriously directed also to alunite, the feldspars, and the granitic 

 rocks, into the composition of which potassium enters, but thus 

 far the cost of separating out the potassium and converting it 

 into a soluble form puts these rocks outside the lists of immediate 

 economic sources of potash for the American farmer and gardener ; 

 however, alunite is looked upon as a promising possibility The 

 Washington scientists in their search for a domestic supply of 

 potash took into consideration also the long-established use of 

 seaweeds as a fertilizer for the soil by farmers living in vicinity of 

 the sea and the well-proven fact that the beneficial efTects of 

 seaweeds thus used are due chiefly to the potash that they con- 

 tain. Under the direction of the Bureau of Soils, detailed surveys 

 of the extensive kelp beds of our Pacific Coast, particularly of the 

 Puget Sound region and the southern half of California, have 

 been made, and the amount of kelp annually available as a source 

 of potash has been computed. Analyses made by the chemists 

 of the Department of Agriculture (J. W. Turrentine, Appendix P, 

 The composition of kelps, pp. 217-221) show that the amount of 

 potash contained by the marine algae varies greatly with the 

 species, place of collection, age of the plant, the part analyzed, 

 etc. The three Pacific kelps that occur in sufficient abundance 

 to make them important as a possible source of potash are 

 Nereocystis, Macrocystis, and Pelagophycus. Dr. Turrentine 

 found that 48-85 per cent, of the dry weight of the bulb of a 

 young Pelagophycus plant consisted of potassium chloride and 

 that Macrocystis, Nereocystis, Pelagophycus, and Postelsia showed 

 an average content of 23.4 per cent, potassium chloride. As a 

 result of the analyses and the field surveys carried on under the 

 direction of the Bureau of Soils, Hon. James Wilson, the recent 

 secretary of agriculture, in his letter of transmittal of Senate 

 Document 190 feels justified in remarking: "It is regarded as a 

 very conservative estimate to put the annual yield of potassium 

 chloride from the Pacific kelps at upward of 1,000,000 tons, worth 



