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repelled the liquid. The injury in the former case being the destruction 

 of the functions of the leaf, in the other only corrosive spots, where the 

 liquid by repulsion had formed itself into drops on the different parts of 

 the leaf He found that the injury produced by nitric acid on the gen- 

 erality of plants was only local, whilst upon the potato plant its effect 

 was immediate and fatal, the whole plant becoming disorganized and 

 its vitality extinct in a few hours. 



In order to support ray opinion, and prove the disease to be atmos- 

 pheric, I have now produced the opinions of scientific and practical 

 men, from England, Ireland, Scotland, France, Holland and America; I 

 think this point is satisfactorily proved. 



I have also proved that the disease is conveyed by means of rain and 

 dew. Having firmly estabhshed these two points, I have proceeded to 

 another important part of the question, and prove by the testimony of 

 several distinguished chemists, that rainwater during thunder storms, 

 contains a large portion of nitric acid, an ingredient which is sometimes 

 destructive to vegetation. I have proved that the disease generally ap- 

 pears after thunder storms, and that it is wonderfully increased by rain. 

 Thus having explained the cause of the rot, I have proceeded to de- 

 scribe the best means of preventing it. I have given plans which are 

 clear, plain and practicable, such as can be tried by every farmer with- 

 out trouble or expense. 



It may be asked why the rot was unknown in the world until 1845? 

 I have produced the evidence of M. Boussingalt, to prove that it has 

 existed for many years in Central America. It should be borne in 

 mind that blights of every kind are produced by certain conditions of 

 the gasses which compose the atmosphere, and consequently the time of 

 their appearance is regulated by no fixed law. 



The British Government paid $97,000 for the expenses of a com- 

 mission to inquire into the nature of the potato disease, and to provide 

 a remedy. Time has cleared away the mystery which clouded the 

 subject, and I hesitate not to assert that the practical farmer will find 

 more useful information in this essay, than has been elicited by the 

 British Government, at a cost of 897,000. 



In making this statement, I do not at all wish to diminish the fame 

 of Dr. Lindley, Sir Robert Kane and Professor Playfair, the three very 

 distinguished gentlemen, who composed the British commission; but 



