No, 6. DEPARTMENT OF AGRICULTURE. 411 



Wilfarth could call attention to the fact that the legumes possessed 

 the power to make use of atmospheric nitrogen and therefore to 

 store up nitrogen in their tissues. This fact has since been investi- 

 gated thoroughly by many scientists, and it is now known to be 

 brought about by living organisms — bacteria — which are the cause 

 of the root nodules of the legumes in which they live, grow and mul- 

 tiply, building up atmospheric nitrogen in themselves into organic 

 compounds. These compounds later on are used by the legume plant 

 which acts as the host for the tiny bacteria. This is the socalled 

 Legume Nodule Theory. Besides the bacteria living together with 

 legumes, the power of other bacteria in the soil to gather nitrogen 

 is also a problem under investigation. 



This nitrogen gathering phenomenon, which is observed in cer- 

 tain kinds of plants only, although it does not in any way cover 

 the demand for nitrogen on the farm has been, and is, especially 

 since it is fairly thoroughly understood, a great blessing to the agri- 

 culturist and agriculture. While this knowledge has helped the 

 farmer and in thousands of instances been the direct cause of pros- 

 perity on the farm, it did not directly help the technical man any. 

 Other scientists, however, besides those directly interested in agri- 

 culture have been at work on the nitrogen problem, and of late 

 years several attempts have been made to manufacture nitric acid 

 and other nitrogen compounds from the atmospheric nitrogen on a 

 large scale by means of electricity, but the efforts were not crowned 

 with real practical success until within these last three or four 

 years. 



That atmospheric nitrogen could be oxidized to nitric acid was 

 mentioned by Henry Cavendish, as long ago as 1786, who had made 

 the observation that nitrogen mixed with sufficient oxygen would be 

 oxidized during large electrical discharges causing high rise in tem- 

 perature. In 1781 he had also observed that, in burning hydrogen, 

 nitric acid also was formed. Priestly also made similar observa- 

 tions, about that time, in regard to the formation of nitric acid by 

 strong electrical discharges, but it was left for our present time to 

 apply that knowledge and make it of real practical value. In 1892 

 Crookes made experiments in the line indicated by Cavendish, but 

 it was especially after the experiments of Lord Raleigh in 1897 were 

 completed, in which the quantity of nitric acid obtained bore a fa- 

 vorable relation to the amount of energy used, that the question 

 was again taken up with renewed vigor in different countries. Thus, 

 in 1900, Dougal and Howies made the attempt to manufacture 

 nitric acid. In 1902 Kowalsky and Moszicki operated in Switzerland 

 using an alternating current of 50,000 volts. At the same time 

 Muthmann and Hofer were making trials in Germany. In United 

 States a company was organized under the name of ''The Atmos- 

 pheric Products Company" with a capital of one million dollars, and 

 which built a factory for the purpose of utilizing the power of the 

 Niagara. This company, also known as the Lovejoy and Bradley 

 company, used 10,000 volts direct current aros, and by this process 

 could produce 70 per cent, nitric acid. The efficiency of the appara- 

 tus, that is, the output of the nitric acid per killowatt year power 

 was good, and the acid was produced at a cost of a little less than 

 1.6 cent per pound for power or energy, using a current generated 

 by Niagara water power at twenty dollars per year kilowatt. But 



