Action of Metallic Poison on Vegetation. 415 



The author has observed, that solutions of metallic salts, which 

 have the property of being decomposed and rendered insoluble by 

 the soil, such as sulphate of copper, acetate of lead, &c. cannot be 

 made to penetrate the vegetables by means of watering. 



If entire vegetables are plunged with their roots into dissolved 

 metallic compounds, these compounds penetrate into all parts of 

 the plants. 



It appears then right, after these experiments, as well as the 

 preceding ones, to admit, that there is no danger to the public health 

 as regards the practice followed by many cultivators. 



Nevertheless, these experiments are far from being absolutely 

 decisive, and their negative results ought not to be admitted without 

 restriction. 



The analytical processes, employed by M. Louyet, are not such 

 as ought to be entirely relied upon. This memoir, says the reporter, 

 M. Martens, is not explicit as regards the analytical methods, by 

 the aid of which the author has discovered the presence of foreign 

 substances in the plants. In fact, he has not employed the method 

 of carbonizing the plant by means of pure nitric acid ; but after 

 allowing the plants to macerate for two or three days, in a solution 

 of caustic potash, he introduced the different solutions into Marsh's 

 apparatus, after having concentrated and neutralised them by sul- 

 phuric acid. The author of the second paper, carbonized the va- 

 rious parts of plants which grew in the poisoned ground, by means 

 of nitric acid, but he does not appear to have got rid of the residue 

 of the carbonisation of the plants, previous to the introduction into 

 Marsh's apparatus. The learned M. Martens remarks, upon the 

 necessity of neutralizing the nitric acid by pure potash, then to dis- 

 place it by pure sulphuric acid ; for it is well known that the presence 

 of nitric acid in Marsh's apparatus would interfere with the disengage- 

 ment of the arseniuret of hydrogen, which is quickly oxidized or 

 decomposed under the influence of this acid. We insist upon these 

 points, because we believe with M. Hemptinne, that it cannot be too 

 boldly recommended to practitioners, to banish from the operations of 

 agricultural industry, as well as from manufactories, the use of this 

 dangerous poison. M. Martens wishing to verify the results of 

 these two papers, watered different plants in pots, such as a young 



