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CONTRIBUTIONS TO OUR KNOWLEDGE OF SOIL- 

 FERTILITY. Nos. vii. to xi. 



Ry R. Grkig-Smith, D.Sc., Macleay Bacteriologist to the 

 Society. 



vii. The Combined Action of Disinfectants and Heat upon Soils. 



In previous researches, I have shown that the action of a moder- 

 ate heat upon soil, differs from that of the volatile disinfectants, so 

 far as the subsequent growth of bacteria is concerned. According 

 to certain authors, the results should be similar, because both bring 

 about the same result, namely, the destruction of the phagocytic 

 protozoa. If the result is the same, it should be immaterial, in 

 cases where the soil has been treated both with disinfectant and 

 heat, whether the one is applied before the other or vice-versa. A 

 preliminary test, with a garden-soil, showed a considerable differ- 

 ence in this respect, and led to further work upon the matter. 



At first, an alluvial soil was used. The heating consisted of 

 exposing it to 60°-65° for 30 minutes, and, where necessary, it was 

 treated with 5% chloroform overnight. The tests were moistened 

 with sterile water to bring the moisture to 16% and the tem- 

 perature of incubation was that of the room, viz., 15°, which 

 gradually rose to 20° as the season advanced. 

 Experiment i. 



