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tion of the dew, moisture, or rain. It is therefore on the backs of the 

 uppermost leaves that the greatest amount of dew lodsjes. 



Now I will prove by the authority of some distinguished chemists 

 that rain and dew, at certain times, contain a deleterious ingredient 

 known as nitric acid, and when m combination with ammonia, as nitrate 

 of ammonia. 



Doctor Ure, in his '' Dictionary of Chemistry," says that the two 

 principal component parts of the atmosphere, when in certain propor- 

 tions, are capable of combining chemically, and forming nitric acid. 



Professor Johnston in his lectures on agricultural chemistry, states 

 that when a succession of sparks is passed through common air, nitric 

 acid is slowly but certainly formed. 



Liebig found nitric acid always present, in seventeen examinations of 

 <lifferent rain which fell during thunder storms, and could only detect 

 it twice in sixty examinations of rain which fell without thunder. He 

 also states that the rain which fell during a thunderstorm which visited 

 Nismes, in France, in 1842, was actually so^ir with nitric acid. 



Mr. Richard Lloyd, in a letter to the Irish Farmers' Gazette says, 

 "that the dropping from a sycamore tree, the leaves of which had been 

 discolored by blight, was blown by the wind on some clothes which 

 were hung up to dry, on a hedge six yards distant, holes were burned 

 in the clothes; and where some drops fell on the arms of a woman 

 who was attending them, there was a sensation of pain, with red spots, 

 which continued for several days. This shows very clearly that some 

 poisonous acid is contained in rain and dew, at the time of the preva- 

 lence of the rot. That rain water contains a considerable portion of 

 ammonia, is a fact well known to all ; and the particular time when it 

 contains the greatest quantity, is when aramoniacal exhalations are 

 evolved from putrid animal and vegetable substances. Nitric acid and 

 ammonia have an affinity for each other, and when they are in combi- 

 nation, they form nitrate of ammonia, which is very powerful and de- 

 structive. 



I have seen so many instances of the rot being caused by rain and 

 dew, that it is quite impossible that I could be mistaken in this par- 

 ticular. 



I have seen potatoes in well-finished drills, perfectly sound and free 

 from all disease, whilst those in badly formed drills were rotten and 



