BUREAU OF SOILS. 295 



a considerable study of the processes involved will be necessary in 

 order to make them useful during peace time. The products of these 

 plants must be available for use as fertilizers and readily convertible 

 into munitions in time of war. Proper use of them is closely asso- 

 ciated with other fertilizer problems and with transportation prob- 

 lems. 



Methods for preventing the great loss now suffered in mining phos- 

 phate rock have shown that phosphoric acid can be prepared in a form 

 suitable for the absorption of ammonia. Inadequate transportation 

 ecjuipment has emphasized the importance of conserving car space as 

 much as possible. By proper use of our nitrogen fixation plants it 

 may be possible to manufacture concentrated fertilizers containing 

 only the three important fertilizer ingredients — nitrogen, phosphoric 

 acid, and potash. The development of the fertilizer industry is 

 toward the manufacture of such a concentrated fertilizer. In this 

 way an enormous amount of car space will be made available for 

 other purposes and a large saving in freight rates, paid on inert 

 material now going into fertilizers, will be effected. In establishing 

 this method of utilizing the nitrogen plants, of conserving phosphate 

 material, and of reducing freight charges, as has been indicated, 

 there are still many questions that must be investigated. 



This bureau initiated M'ork along these lines several years before 

 the World War. Work on the Haber process for nitrogen fixation 

 was begun and carried on by this bureau, and at the entrance of 

 the United States into the war the Ordnance Department requested 

 the use of the experimental apparatus constructed at the Arlington 

 Farm Laboratory. A considerable force from the War Department 

 was assigned to this laboratory until the armistice was signed. The 

 work was then transferred to the American University, and the co- 

 operation between this bureau and the War Department for the 

 study of nitrogen fixation has been continued since at the American 

 University Fixed Nitrogen Research Laboratory. The three lines 

 under investigation were the synthetic, or Haber process; the prep- 

 aration and use of cyanamid ; and the fixation of nitrogen by means 

 of the silent discharge. , 



In the work on the Haber process the apparatus and materials in 

 use at Arlington Farm were used for establishing a testing plant 

 at the American Universitj"^ for testing catalysts at a pressure of 

 100 atmos})heres. 



Special investigation has been continued on the method of re- 

 moving ammonia formed in this process from a mixture of hydrogen 

 and nitrogen gases. The ordinary method of removing by liquefying 

 the ammonia on cooling results in the gases leaving the cooling 

 chamber carrying about 1 per cent of ammonia. As these gases 

 lead to the catalyst chamber, the efficiency of the catalyst is greatly 

 reduced. The effort has been to develop a method for more complete 

 removal of ammonia. 



A study has been made of the use of several solids of high ab- 

 sorptive rapacity for this purpose, and promising results have 

 been obtained. In addition, a stiidy has been made of several rupiids 

 which have a high al)Sorptive capacity for ammonia. Vapor pres- 

 sure studies indicate that some of these liquids may be used with 

 success. A small, semicommercial unit for the testing of these ab- 



