HEATED AND TREATED SOILS 253 



shown by exposing sound apples to the vapour of various 

 antiseptics under bell-jars at ordinary atmospheric temperatures : 

 with chloroform, ether, or carbon disulphide the fruit was found 

 to have become much discoloured after twenty-four hours, and 

 after eleven days it was soft, brown and decomposed, nearly, or 

 quite to the core. The action with ether was more energetic 

 than with the other two substances ; but petroleum ether had 

 comparatively little effect. Instances have been found in which 

 much simpler chemical changes than those occurring in vegetable 

 matter can be effected by the antiseptics. 1 



To all appearance the effect of heat and antiseptics on soil is 

 closely similar ; the soluble matter is increased, the germination 

 of seeds is adversely affected, and the growth of plants is favour- 

 ably affected ; and from all three of these phenomena a similar 

 estimate of the relative magnitude of the effects is obtained, 

 namely, that the treatment with antiseptics is equivalent to 

 heating to about 70 C. The increase in soluble matter might 

 be accounted for by the removal of some coating of oily or 

 resinous matter from the particles of soil, but this is rendered 

 somewhat improbable by the fact that the treated soil when kept 

 for some time, even in a fairly dry condition, reverts towards its 

 original state, just as heated soil does. That the increase pro- 

 duced by the treatment is not due to altered bacterial activity 

 consequent on the treatment, was shown by the fact that the 

 increase was found to have occurred within one hour after the 

 treatment, during which time no appreciable action from bacteria 

 could have occurred. Eighteen hours later a very appreciable 

 diminution in the soluble matter was observed. 



'All . these facts render it clear that no true estimate can be 

 obtained of the behaviour of freshly heated or freshly treated 

 soils towards plant-growth by growing plants in them, for, long 

 before these will have grown sufficiently for measurements to 

 be made, the soils will have become materially altered. The 

 results which are apparent are that growth is very largely 

 increased even up to 200 per cent. with the temperature to 

 which the soil has been heated, so long as this temperature does 

 not exceed 80 or 100. Russell and Darbishire's results 2 with 

 a number of different plants may be quoted, and similar results 

 with apple trees have been obtained at Woburn (IX, Appendix, 

 p. ii) ; but none of these would disprove the presence of a toxic 



1 S. Pickering, Chem. Soc. Trans., 109, 242 : "Action of Heat and Anti- 

 septics on soil/' Journ. Agric. Soc., 1908, III, 1-21. 



2 E. J. Russell, Journ. Agric. Sci., 1905, I, 261-79; E. J. Russell and 

 F. V. Darbishire, Journ. Agric. Sci., 1907, II, 305-26. 



