420 The Woburn Pot-Culture Experiments , 1913. 
One-half the number of pots were filled with the soil in its 
natural state, the other half with soil which had been previously 
heated to a temperature of 80° C. — 100° C., the arrangement for 
heating the soil being such as to obtain a moist heat and not a 
dry one. 
The additions of lithium phosphate determined upon were 
*0025 per cent., and ’005 per cent, of the metal. Those of 
magnesia were based upon the magnesia contained in the soil 
(•396 per cent.), and the total magnesia was increased to *792 
per cent., 1T88 per cent., and 1*584 per cent, respectively. The 
materials to be added were thoroughly mixed with the whole 
of the soil contained in each pot. It will be noted, in regard to 
the additions of magnesia, that with the highest amount an 
equality between the lime and magnesia was practically reached. 
The main object in using the natural and the heated soil 
side by side, was to ascertain whether the heating of the soil 
would remove any of the toxic properties possessed by the 
subsequently applied lithium phosphate and magnesia, it having 
been suggested that the harm done by these to plant life is 
due to the influence which they exert on the bacterial con- 
stituents of the soil. One might therefore suppose that the 
heating of the soil would obviate such injury. 
The tomato plants were raised in a seed-bed of ordinary 
soil, and when they had obtained a growth of about six inches 
they were planted in the respective pots. This was on 
May 12, 1913. 
Within two days of their planting, differences began to 
appear. In the natural soil without any addition there was 
more rapid growth than in the heated soil. The leaves of the 
plant were, however, much lighter in colour than were those 
of the heated soil, the latter being stronger and more robust 
plants, and of distinctly dark green colour. Where lithium 
phosphate had been added in small amount the growth was 
retarded in both the natural and the heated soils, and the leaves 
soon began to turn yellow and to curl up. With the heavier 
application of lithium phosphate on the natural soil the growth 
was also much retarded, this being even more the case with the 
heated soil, the plant on the latter being decidedly small, and 
presenting a scorched appearance. The addition of magnesia 
produced somewhat similar effects, these being more marked 
on the heated soil than on the natural, and also more 
pronounced with the heavier than with the lighter application. 
The plant grew on, and, as the season advanced, some of 
the earlier effects passed away ; but, speaking generally, the 
plants in the natural soil were taller, but weaker and lighter in 
colour than those in the heated soil. The applications of 
lithium phosphate to the natural soil seemed to show hardly 
