38 ELECTRICAL STRUCTURE AND 



WATER IN ITS RELATION TO PLANT LIFE. 



If, as it would appear, a constant supply of electricity 

 from the earth is necessary to the well-being of everything 

 that grows therein, the fact that dry soil is a bad conductor 

 of electricity assumes an important aspect. In the 

 experiment about to be described a quantity of earth was 

 dug from the garden, carefully sifted and weighed, and 

 equal quantities were placed in three porcelain pans of 

 equal dimensions. These were labelled 1, 2, and 3. Nos. 

 1 and 2 were put in a gas oven and baked, the soil being 

 frequently turned over, until all moisture was expelled. 

 No. 1 was then protected from moisture, and after a 

 solution of one per cent, of ferro-sulphate had been mixed 

 with the soil in No. 2 it was again baked until it had become 

 dry ; No. 3 was left untouched. 



A galvanometric test of pan No. 1 gave no deflection 

 whatever, whilst Nos. 2 and 3 (No. 2 being dry) exhibited 

 no difference in their electrical conductivity ; pointing to 

 the fact that, considered as an electrolyte, ferro-sulphate 

 was an efficient substitute for water. The next step was 

 to sow exactly the same weight of mustard seed in each of 

 the three pans, which were then placed in a room in a 

 diffused light with free access to the air. 



No. 1. Baked dry earth. 



No. 2. Baked dry earth containing ferro-sulphate, 



and 

 No. 3. Moist earth as taken from the garden. 



No. 3 was watered in the usual manner that is to say, 

 care was taken to keep the soil thoroughly moist but Nos. 

 1 and 2 were given only ten per cent., in the form of spray, 

 of the quantity of water accorded to No. 3. 



The outcome of the experiment was that while the seed 

 in No. 1 did not germinate, the growth in Nos. 2 and 3 

 exhibited no apparent difference. 



