20 



Overhead Electrical Discharges. 



[APRIL, 



particularly in the direction of direct utilisation of atmo- 

 spheric nitrogen. These are clearly points of very great 

 importance, only to be settled finally by careful quantitative 

 work in the laboratory. 



Other general points need a very brief mention, in par- 

 ticular the possibility of changes in the atmosphere and soil 

 surrounding the plant as a result of the discharge. It is, 

 of course, well known that the electrical discharges in thunder 

 w 7 eather bring about a combination of the oxygen and 

 nitrogen in the air, that the products of this combination 

 are carried to the earth in the rain, and that thus every year 

 small quantities of nitrate are added to the soil. It is also 

 a well-established fact that the silent discharges of electricity, 

 as they are called, as in the case of the quiet continuous 

 discharge from the overhead wires in these large scale 

 experiments, are capable of bringing about chemical com- 

 binations, and thus the result of having such a discharge 

 above the plant might be expected to be a very slight but 

 continuous addition of nitrate to the soil around the roots. 



Many of the observers of the electrified crops have sug- 

 gested this explanation, on account of the darker green colour 

 of the foliage as compared with the control plants. This 

 feature has been very noticeable in the wheat experiments on 

 two occasions. 



At the same time, it should be pointed out that in chemical 

 combinations between gases under point discharge, which 

 should be a fairly comparable case, it is always stated that 

 most combination is produced with the point (equivalent to 

 the overhead wire) charged negatively, and this does not 

 agree with Mr. Newman's statement that the overhead system 

 is of most practical value when charged positively. 



Finally, it must not be forgotten that bacterial activities 

 within the soil and the interchange going on between root and 

 soil, are both important factors in the plant economy, liable 

 to undergo a definite change under these conditions. What 

 direction those changes might be likely to take is too specu- 

 lative a subject to consider here and must await full experi- 

 mental investigation. 



