210 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



attended with technical difficulties and no important results can as 

 yet be announced. 



Investigations on city wastes have been continued and an appa- 

 ratus and processes for rendering garbage and other similar wastes 

 have been devised, which it is believed will prove superior to those 

 now in use for this purpose. A full report on city wastes is now in 

 course of preparation. Some work also has been done in determining 

 the availability of various nitrogenous fertilizer materials when 

 applied to the soil, and this work is being continued. 



A study of the subject of ammonia from the by-product coke ovens 

 has been made and published. 



PHOSPHATES. 



At the Arlington laboratory an electric furnace has been installed 

 and work on the volatilization of phosphoric acid from phosphate rock 

 has been begun. In connection with this work the question arose 

 whether it would not be possible, and, if so, more economical, to collect 

 phosphoric acid by means of the Cottrell precipitator instead of pass- 

 ing the fumes through absorption towers. A precipitator was installed 

 and, while minor adjustments remain to be made, the essential fact 

 that phosphoric acid may be economically collected in this way has 

 been demonstrated. This work involved the installation of electrical 

 equipment for delivering a current of 50,000 volts. 



The work on the fertilizer value of raw phosphate rock has been 

 continued, and the final report, giving the results of this investigation, 

 is now nearing completion. 



Large supplies of sulphuric acid are used by the fertilizer manufac- 

 turers in the preparation of acid phosphate by present methods. A 

 process for producing sulphuric acid has been perfected and patented 

 which gives promise of being much more satisfactory than the process 

 now in use. 



GENERAL. 



The problem of producing concentrated fertilizers containing all 

 three fertilizer ingredients or any two of them has been attacked from 

 several directions, and methods have been worked out in the labora- 

 tory for producing ammonium-potassium-phosphate, potassium-phos- 

 phate, and ammonium-phosphate by processes which are new and very 

 promising. Patents on all these processes, for the benefit of the 

 people of the United States, have either been secured or have been 

 applied for. 



The scarcity of potash and the high prices asked for phosphates 

 and nitrogenous materials have stimulated the search for sources of 

 potash, nitrates, and phosphates within the country, with the result 

 that a large number of samples have been received with requests for 

 analysis. In many instances these have seemed to offer sufficient hope 

 of disclosing valuable sources of fertilizer ingredients to warrant analy- 

 sis, and a considerable volume of such routine analytical work has 

 been turned out. 



Many requests from private individuals have been received for 

 information on the subjects of fertilizer resources, manufacture, and 

 practice, and wherever possible this information has been furnished. 

 This has involved a large amount of library research in addition to 

 the actual preparation of the replies. 



