388 Influence of Mines upon Land and Livestock 



constructed to obtain a store of rain water for watering the pots. This 

 special collector consisted of a wooden framework over which has been 

 fixed a sheet of strong canvas. The water thus collected was tested and 

 found to be free from any trace of metaUic impurities injurious to 

 plants. 



I. Influence of Metalliferous Minerals upon Fertility. 

 1. Effect of Galena upon Oats. 



For this experiment specially selected galena, free from blende and 

 other metalliferous substances, was used. It was ground until it passed 

 through a sieve containing 10,000 meshes to the square inch. The 

 residts are given in Table XI. 



Variety of seed Webb's Newmarket. 

 Time of sowing May 14th, 1914. 

 Time of cutting September 3rd, 1914. 



In this experiment, therefore, the addition of galena to unaffected 

 soil lowered fertility only to a comparatively slight extent. The develop- 

 ment of red pigments, and the other usual peculiarities in the appear- 

 ance of cereal crops grown in mine affected fields, were observed only 

 in Pots 33 and 34; and even with these the effects were not very pro- 

 nounced. See Photograph "B." 



2. Influence upon catch crop — Trifoliitm. 



After removing the oat crop trifolium (crimson clover) was grown 

 as a catch crop. Thirty seeds of trifolium were sown in each pot on 

 October 19th, 1914, and the plants were diminished in number to 20 

 per pot a month later. During germination, and for about a month 

 afterwards, growth seemed normal and uniform in all the pots. Sub- 

 sequently a very marked differentiation became evident. The plants 

 growing on the soil to which galena had been added before sowing the 

 oats, acquired a distinctly darker green colour, and the leaves curled 



