BY R. GREIG SMITH. 

 Experiment iv. 



727 



The experiments show decided differences between the sets 

 according to the order of treatment. The effect of heat is small 

 compared with that of chloroform, and in the tests receiving the 

 double treatment, the differences between heat then chloroform, 

 and chloroform then heat, are marked; and it is fair to conclude 

 that the order of treatment is not immaterial, when a soil is heated 

 and treated with a volatile disinfectant. Why this should be so, is 

 not clear. 



The great differences in the counts of the soils treated with heat 

 alone, and chloroform alone, especially when the soils are fairly 

 rich in organic matter, show that the volatile disinfectant makes 

 more nutriment available for the bacteria. The study of the nutri- 

 tive effects of extracts of soils before, and after chloroform-treat- 

 ment, frequently shows this in a marked manner. (Posted p. 733.) 



After treatment with a volatile antiseptic, the particles of soil 

 are undoubtedly altered physically, for such soils are difficult to 

 wet. This has been shown by Egorow, and is confirmed by the fol- 

 lowing observations upon the capillary rise of water. 

 . Capillary Power. 



145 hours. 



Normal garden-soil 

 Chloroformed garden-soil. 



29 cm. 

 3 cm. 



Once the soil is thoroughly wetted, water probably passes as 

 freely through it as through an untreated soil. At any rate, experi- 



