224 ANNUAL REPOETS OF DEPARTMENT OF AGRICULTURE. 



The possibility of economically oxidizing ammonia to nitric acid 

 by electrolysis was also taken up toward tTie close of the year, and 

 this investigation is progressing very satisfactorily. Already it has 

 been demonstrated that under certain conditions ammonia may be so 

 oxidized with a very moderate consumption of power. 



Other work with nitrogen has included efforts to secure a more 

 complete saving of waste products, such as garbage, by our large 

 cities, and investigations of the problem of inoculating such media 

 as peat with nitrogen-fixing bacteria. While this latter work has 

 opened up some very promising avenues for further research, it has 

 not as yet given results in the way of any large increase of fixed 

 nitrogen. 



The bureau's work on phosphates has included several lines of 

 investigation. In cooperation with a commercial concern, a plant on a 

 commercial scale was erected at Hoboken, N. J., to test the bureau's 

 process for producing high-grade phosphoric acid by use of the 

 electric furnace and electric precipitator. This plant was installed 

 by a representative of the bureau and run for several months in 

 practically continuous operation. The results of the test showed the 

 entire practicability of the process for users of pure phosphoric acid 

 and also demonstrated that the operating costs were low enough to 

 make it probable that in the near future the process may be compet- 

 ing with the old sulphuric acid process for acid phosphate produc- 

 tion. One private commercial plant to use this process is being 

 erected and several others are in contemplation. A publication giv- 

 ing the results of this work is now in press. 



In the effort further to reduce the costs of operation, experiments 

 are now being conducted at Arlington on the possibility of smelting 

 the phosphate rock by means of a hot-air blast instead of electric 

 current, and also on the possibility of using mine-run phosphate 

 rock instead of washed and screened material. From small-scale 

 laboratory experiments both these suggestions seem entirely feasible. 

 Work is also contemplated looking to the recovery of by-products, 

 such as hydrofluoric acid, and the utilization of the slag. 



A study of the fluorine content of phosphoric acid, involving new 

 and improved methods of analysis for fluorine, has also been made 

 and published. The regular annual survey of the phosphate industry 

 was also made. 



Steady progress is being made in developing American sources 

 of potash, and during the current calendar year approximately one- 

 tenth of our normal consumption will be produced in this country. 



The bureau's potash investigations have taken two main lines, 

 namely, the survey of the cement and blast-furnace industries, where 

 potash may be recovered as a by-product, and the work with kelp 

 on the Pacific coast. During the year a complete survey of the 

 cement industry of this country and Canada was made to determine 

 with some degree of accuracy the amount of potash being volatilized 

 and lost at cement mills. Samples of raw mix and finished cement 

 were secured from all mills having 100 barrels capacity or over and 

 analyzed for potash. Knowing the ratio of raw mix to finished 

 cement and the producing capacity of each mill, it was possible to 

 calculate accurately the amount of soluble potash being lost. This 

 study demonstrated that with suitable collecting apparatus the 

 cement mills of this country might produce approximately 70,000 



