808 EXPERIMENT STATION RECORD. 



which shoAved that the production of nitrates in the soil must be 

 due to living- organisms. This work was repeated by Warington, Avho 

 continued to investigate the conditions favorable to the ^^I'ocess. 

 He showed that light would inhibit the change and that the drying 

 of the soil was sufficient to destroy the organism ; he also investigated 

 the distribution of the organism, and showed that it was confined 

 to the surface layers of ordinary soil, being only present in any 

 (juantity in the portion usually stirred by the plow. 



" Observing that the oxidation of the annnonia or urea employed 

 sometimes stopped at the stage of nitrite, he succeeded in demon- 

 strating that the process in ordinary soils takes place in two stages 

 due to different organisms — one oxidizing ammonia to nitrous acid, 

 the other completing the oxidation to nitric acid. Warington had 

 actually accomplished the final step in the isolation of the two organ- 

 isms, though he had not brought his work to the stage which satisfied 

 himself, when his researches were unfortunately interrupted, and 

 before he could resume Winogradsky published his elegant method 

 of isolating the nitrous and nitric organisms by the use of a nutrient 

 silica jelly. The circumstances Avhich led to Warington thus missing 

 the credit of the crowning point of his long researches on nitrifica- 

 tion undoubtedly caused him bitter disappointment. He continued 

 to live in Harpenden, but took no further part in research. 



" In the course of his investigations on nitrification, Warington 

 also observed and studied that other process of denitrification, by 

 which previously formed nitrates are reduced again, often with loss 

 of the nitrogen as gas. In later years this subject became very promi- 

 nent for a time, but the essential conditions of the action had been 

 laid down before in Warington's papers. He also investigated the 

 method of estimating small quantities of nitrates by means of indigo, 

 and devised a standard process which, in a simplified form, is now 

 used l)v most water analysts. . . . 



•■' AVarington's scientific work is distinguished b}^ clearness and 

 precision. The range is not Avide, but everyAvhere it shows the minute 

 care and the regard for accuracy with Avhich he Avorked. In these 

 respects his Avork only reflected his personal character." 



He was Sibthorpian professor of rural economy at Oxford from 

 1894 to 1897, a chair held for several years by Sir Henry Gilbert. 

 His little book on the Chemistry of the Farm, first published in 

 1881, has gone through fifteen editions. He was a felloAV of the 

 Royal Society and the Chemical Society, being Adce-president of the 

 latter from 1889 to 1893. Since 1894 he had been examiner in agri- 

 cultural science to the board of education. 



Professor Warington's health began to fail about a year ago, Avhen 

 he underAvent an operation, which greatly benefited him for a time, 

 but eventually a recurrence of the maladA^ led to his death. 



