378 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



A study has been undertaken of some of the physical properties 

 of various soil types and the variation of these with the soil horizons. 

 This work is being done in cooperation with the Soil Survey to assist 

 in the classification of soil types. 



Routine mechanical analyses of soil-survey samples have been 

 continued, and in addition a large number of samples have been 

 examined for the United States Geological Survey, the Reclamation 

 Service, Bureau of Public Roads, and other offices in the Government. 



Regular work on the design and construction of apparatus has 

 been continued, and a number of pieces of special apparatus for use 

 in the laboratories and by the Soil Survey field parties have been 

 constructed. 



FERTILIZER RESOURCES. 



During the last fiscal year the bureau continued its general funda- 

 mental work to develop our resources in fertilizer materials. It has 

 furnished farmers and others interested in fertilizers technical 

 information regarding fertilizers, lime, and manure, their sources of 

 supply, manufacture, purchase, and mixing, and has advised on 

 many problems pertaining to fertilizers that have arisen in the 

 various departments of the Government. 



Work has been continued on the production of phosphoric acid by 

 the volatilization process. One of the details worked out is the best 

 proportions of silica, carbon, and phosphate rock to be used for the 

 rapid evolution of phosphoric acid. From laboratory experiments 

 it has been found that the volatilization of phosphoric acid can be 

 brought about under slightly reducing conditions, including tem- 

 peratures considerably below those generally considered necessary. 

 It has also been shown that by replacing the sand ordinarily em- 

 ployed in this process with potash-bearing shales, phosphoric acid 

 and potash may simultaneously be evolved at a lower temperature 

 than was thought possible for either phosphoric acid or potash. It 

 would be a distinct advantage technically if both of these materials 

 could be volatilized in one operation, using the shale material as a 

 slagging agent. Outside commercial interests have already ex- 

 pressed a willingness to try out the fuel-fired furnace for producing 

 phosphoric acid as it has been largely developed in this bureau. A 

 bulletin describing the work on the volatilization of phosphoric acid 

 is now in press and will be issued shortly. 



A survey of the amount of potash obtainable as a by-product 

 from blast furnaces has been completed and a publication embodying 

 the results has been prepared. It has been definitely established 

 that the potash liberated from furnaces where certain types of ores 

 are used may be utilized commercially by the employment of tech- 

 nical methods already developed, and researches are in progress 

 which are designed to effect improvements in methods so that the 

 potash evolved from all furnaces may be made industrially valuable. 



The problem of rendering commercially available the enormous 

 domestic supply of potash represented by the greensand deposits of 

 New Jersey, the alunite deposits of Utah, the leucite deposits of 

 Wyoming, and the cement dust of various parts of the country has 

 been attacked from entirely new points of view. The announce- 

 ment of conclusions at this time would be premature, but the results 

 obtained to date are of a very encouraging nature and offer the 



