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THE TOXIC ACTION OF TRACES OF COAL GAS 

 UPON PLANTS 



By J. H. PRIESTLEY. 



The fact that under certain conditions small quantities of unburnt coal 

 gas may produce very deleterious effects upon vegetation is obviously 

 of considerable economic importance. Both in Germany and in the 

 United States these effects have frequently been under investigation but 

 in this country they have attracted less attention. The earlier recognition 

 of this type of poisoning of vegetation in other countries may be due in 

 part to the general differences in composition between the illuminating 

 gases employed, but the composition of coal gas in this country varies 

 within wide limits and a change in the general methods of coal carbonisa- 

 tion might at any time so alter the average composition of British coal 

 gas that this phenomenon might become of greater importance in British 

 horticulture. Gas poisoning of vegetation probably occurs at present in 

 this country but, as the American workers have found (5, he. cit. p. 28), 

 the absence of specific diagnostic characters enabling the damage to be 

 accurately assessed, makes it difficult to appraise the economic im- 

 portance of this particular source of injury to plants. 



As the result of experiments in another field of investigation, the 

 writer's attention was drawn to some of the cases of injury produced 

 experimentally upon plants by the use of coal gas, and the structural 

 changes resulting from gas poisoning were therefore examined. The 

 preliminary results of this examination appear so significant that they 

 are presented in this paper. 



As so little attention has been devoted to the subject in this country, 

 a brief summary is first given of the recorded effects of gas poisoning 

 and of the definite information obtained by both German and American 

 workers as to the constituents in the gas responsible for the toxic action. 

 Very varied phenomena have been discussed in connection with the 

 subject and throughout this paper attention will be restricted to cases 

 where injury is reported as the result of the action of relatively low 

 concentrations of coal gas. In such cases a common cause for the toxic 

 effect produced seems to be clearly demonstrated. On the other hand 



