SOIL AND WATER 103 



I wanted to get an idea of the quantity of water needed 

 for growth as compared with the quantity necessary to 

 give conductivity and capacity to the soil of a pot plant. 

 Dry soil has no capacity and is of the nature of a dielectric, 

 so that if it is to remain dry other means must be taken to 

 administer to the requirements of the plant. 



I took, sifted and weighed a certain amount of soil. This 

 I divided into two equal portions and placed them in a gas 

 oven until every particle of moisture had been expelled. 

 One of these moieties was then saturated with a solution 

 of two per cent, of ferrous sulphate and replaced in the oven 

 until complete evaporation had again taken place ; call 

 these soils A and B. 



I then selected two roots of grass, of the same size and 

 species, and potted them, one in Soil A and the other in 

 soil B, containing the ferrous sulphate ; electrifying the 

 latter by means of a dry cell of 1 ,5 volts. Both pots were 

 then placed in a cool greenhouse, in a good light and in a 

 position where no moisture could reach them. This on 

 August 3rd, 1918. 



The following are extracts from my notebook : 

 " Each root was slightly moist. Weight of each, |-oz. when 

 washed clear of soil ; blades cut to 2-inches. Green- 

 house very dry. Light good, with ample sun. 

 " August 12th : Blades of both withering. Gave 1-oz. of 

 water to each, and propose to continue this daily. 

 " August 14th : B showing signs of life, but not A. 

 " August 24th : B throwing out fresh shoots. 

 " August 25th : A is showing three small green blades ; 



B has more than twenty. Stopping all water. 

 " September 7th : A still survives but is withering ; B has 

 a good display with blades 4|-inches high. Neither 

 have had any water since August 25th. 

 *' September 14th : A seemingly dead ; B flourishing, with 

 blades 5|-inches high, whereas those of A never 

 exceeded 2-inches. 

 "September 19th: B still vigorous hut growth not 

 maintained. 



