1847.] Potato Disease. 219 



to be ripe. This suggested the idea that the disease was atmo- 

 spheric. When I dug my potatoes, I found that the part of the 

 tuber attached to the vine \vas affected before the opposite end, 

 which showed that the disease was communicated from the vine; 

 other observations confirmed me in the conclusion, that the disease 

 was atmospheric. 



My next inquiry was, what is there in the atmosphere to pro- 

 duce this efTect? A little consideration pointed me to its oxygen, 

 M'hich is known to chemists as the great agent of decay. But 

 here an objection arose; for if oxygen was the cause, why had it 

 not produced this effect long ago. This was a question, that for 

 a time I was unable to solve to my satisfaction. At first the idea 

 suggested itself, that the plant had deteriorated, and become weak, 

 and unable to bear the effects of the oxygen as well as formerly, 

 and that it would be necessary to raise a new plant from the seed. 

 Accordingly I saved some balls for that purpose, when I learned 

 that the experiment had been tried without any beneficial result, 

 in districts where the disease had existed for some time. I was 

 now more fully satisfied that oxygen was the cause of the disease, 

 but could not account for all the phenomena attending it, except 

 on the supposition of an excess of that principle. At leno-th in 

 perusing Leibig's Agricultural Chemistry and Physiology, 1 found 

 that he stated as a fact that oxygen had been known to have been 

 on the increase for a thousand yeais, and at the present time it 

 was in considerable excess. This I considered a confirmation of 

 the correctness of my conclusions in regard to the subject, and still 

 consider it to be so. And such observations as I have been able 

 to make since that time, all tend to establish my theory. 



I also noticed that many other things were affected, by what 

 seemed to me to be the same disease. Several kinds of fruit, and 

 forest trees particularly, the Quercus alba, or white oak, among 

 the latter, the lower leaves of which (and especially those that 

 stood in the open field, where by the free circulation of air, a larg-e 

 amount of oxygen came in contact with them,) presented indica- 

 tions of disease, about the middle of the 8th month, (August,) si- 

 milar to that of the potato plant. The outer ends of the petals of 

 the apple, plum, and quince blossoms turned brown, even while 

 hanging on the trees. A circumstance which I believe has not 

 happened until within a few years. 



Having thus become satished of the cause of the disease, my 

 next inquiry was, by what means can it be prevented? And here 

 my attention was turned to quick lime, knowing it to be one of 

 the greatest absorbents of oxygen in nature. I thought that this 

 article thrown on or about the potato vines while growing, would 

 so absorb the oxygen, as to take off the excess and prevent its de- 

 leterious effects. This idea I mentioned to one of my friends, he 



