412 



Vegetable Physiology. — Action of Metallic Poisonous Substances upon 

 Vegetation. Communicated by E. T. Downes, Esq. 



In certain localities it is the practice to spread upon the soil 

 metallic poisons, such for example as arsenious acid, for the purpose 

 of destroying insects. These proceedings, so likely to excite the 

 fear of the public, seem worthy of being submitted for the opinion 

 of some learned Society. 



The Academy of Brussels has taken the initiative in bringing this 

 question forward ; two memoirs have been presented ; we intend 

 giving an analysis of these works. 



We will not attempt here to recall to mind all that has been 

 written upon the question which now engages our attention. Suffi- 

 cient for us to say, that the views of the illustrious historian of the 

 Alps, Theodore de Saussure, have been fully confirmed. " The roots 

 of plants," he writes, " are niters of too fine a form to absorb any 

 substances that are not fluid. If they admit solids, it is necessary 

 that they should be so attenuated, so divided, that their diffusion 

 in the liquid has all the characters of a true solution." 



In a note presented last year to the Academy of Brussels, M. de 

 Hemptinne declared, that having submitted to the ordinary pro- 

 cesses of analysis, the various parts of carrots, potatoes, oats, and 

 wheat, which he had sown and cultivated upon land, on which he 

 had strewed 250 grammes* of arsenious acid to the square metre,f 

 he could not discover the least trace of arsenic. All the vegetables 

 were well- grown, and arrived at maturity, without having presented 

 any thing particular during their growth. 



The results of the experiments of the Royal Academy of Brussels 

 are confirmed, as will be seen by the account which we now give. 



The author of the first memoir, M . Louyet, Professor of Chemistry, 

 at the Central School of Brussels, has impregnated the soil with 



* Gramme, 15.444 grains, 

 f Metre, 49.371 inches. 



