1917 J Forbes: Irrigation Effects of Copper Compounds Upon Crops 421 



TABLE XIII ((■) 



Fifth experiment (1905) 



Corn CuSO^ Distilled .01— .05 .1 — .5 



Corn Cu(OH)2.CuC03 Distilled .01— .05 .1 — .5 



Indicating equal toxicity of Cu as sulphate and as carbonate, and (com- 

 pare second, fourth and eighth experiments) great toxicity to corn in 

 distilled water. 



TABLE XIII (d) 



Third experiment (1905). 



Beans CuSOi Distilled .1 — .3 



Beans Cu(0H)o.CuC03 Distilled .1 — .3 



Toxicity to beans of Cu as sulphate and as carbonate was the same. 



TABLE XIII (e) 



Seventh experiment (1905) 



Squash CuSO, Distilled .01— .05 .1 — .5 



Squash Cu(0H)„.CuC03 Distilled .01— .05 .1 — .5 



Toxicity to squash of Cu as sulphate and as carbonate was the same. 



TABLE XIII (/•) 

 Second experiment (1905) 



Cu in solution 



. A 



Copper salt Kind of Growth retarded Growth arrested 



Culture employed water between, p. p.m. between, p.p.m. 



Corn Cu(0H),.CuC03 Well .1 — .3 .8 —1. 



Beans Cu(0H),.CuC03 Well .1 — .3 .8 —1. 



Toxicity of copper as Cu(0H)a.CuC03 to corn and beans was the same. 



TABLE XIII (g) 



Fourth experiment (1905) 



Corn Cu(0H)o.CuC03 Well .05— .08 .8 —1. 



Squash Cu(0H),.CuC03 Well .1 — .3 .8 —1. 



Corn was somewhat more sensitive to copper as Cu(OH)2.CuC03 than 

 squash. 



TABLE XIII (h) 



Sixth experiment (1905) 



Beans Cu(0H),.CuC03 Well .1 — .3 1. —3. 



Squash Cu(0H),.CuC03 Well .1 — .3 .8 —1. 



Beans and squash were about equally sensitive to copper as Cu(OH)o.- 

 CuCOa 



These experiments, which are not stated in complete detail 

 here, indicate quite clearly: 



1. That the toxic effects of copper are less in the presence of 

 the salts ordinarily contained in well waters than in distilled- 



