90 



in a pot, each experiment being in duplicate. In 1922, .25 per 

 cent, of lead had produced a crop somewhat in excess of the 

 control, but with .50 per cent, only a few stunted plants were 

 left, and with 1 per cent, everything was killed. 



Wheat was sown again in the old pots on December 23rd, 

 1922, after the soil had been turned out, sieved, and replaced. 

 The plants came up quite well with the .25 per cent, and .50 per 

 cent., but with 1 per cent, only a few weak plants appeared, and 

 these gradually died off. For a time the .25 per cent, and the 

 .50 per cent, looked about as good as the control, but about 

 July, 1923, the .50 per cent, began to show a marked toxic effect. 

 The crops when reaped gave the following comparative results : — 



From this it is clear that the toxic influence of 1 per cent, and 

 .50 per cent, of lead used as chloride will continue for a second 

 year, and that even .25 per cent, will show, in a second year, 

 some ill effect. It is true that in the first year .25 per cent, gave 

 some increase of crop, but it has to be remembered that then 

 some of the plants were destroyed, while the rest, as is often the 

 case with pot experiments, developed abnormally. In the form 

 of chloride 0.25 per cent, of lead must, therefore, be considered 

 harmful. 



ii — New Series. 



The quantities decided on were .20 per cent., .30 per cent., 

 .40 per cent, and .50 per cent, of lead as chloride. The soil now 

 used was from Lansome Field, and the salts were mixed with the 

 whole soil ; experiments were, as usual, in duplicate. 



The wheat was sown on December 23rd, 1922, and came up 

 well in all the pots, none of the plants being killed off. The 

 .20 per cent, application, and possibly the .30 per cent., seemed 

 to show an improvement on the control, but with the higher 

 amounts there was a gradual diminution. The crops were cut 

 on August 13th, when they gave the following comparative 

 returns : — 



Lead Chloride upon Wheat, 192 3. 



