New York Agricultural Experiment Statiox. 777 



uniform efficiency of treatment, it would be well to expose the potatoes 

 in shallow trays rather than in crates or boxes. 



Potatoes placed directly over the fumigating vessel are liable to 

 severe injury from the rising, undiluted gas; and they should never 

 be so placed. This fact was known before the injurious fumigation 

 was made; so that no crates were placed above the mixing pans, nor 

 were any nearer than 2| feet. This injury to tubers directly over 

 the generator was considered so well established that only one test 

 involved such placing of the tubers. In this case two potatoes 

 placed in a wire basket 6 or 7 inches above the chemicals were much 

 more seriously injured than others on the bottom of the chamber. 

 Other tubers near the top of the chamber but not directly over the 

 generator were no more injured than those on the floor; and those 

 placed very close to the generator, on the bottom of the chamber, 

 were as free from injury as those farther away. Any injury to the 

 skin of the potato, like a pin prick, was sure to result in an injured 

 spot; but the tests did not support the view that injury can result 

 only where the skin is broken. If this theory be true, there could 

 have been no tubers with unbroken skins in some of the tests; for 

 every potato showed injury. 



The factors hitherto mentioned could not, all to- 

 Small quantity gether, have caused the injury that followed the 

 of potatoes first fumigation, though some of them may have 



the true cause, had a tendency to increase or to diminish it. As 



the subsequent tests plainly showed, it was the use 

 of so large a cellar for the disinfection of a comparatively small 

 quantity of potatoes that led to the trouble. 



In each test in which 12 lbs. or more of potatoes to each cubic 

 foot of space in the disinfection chamber were exposed to the action 

 of gas at the strength commonly employed, no injury of any kind 

 resulted; when from 5 to 10 lbs. of tubers to each cubic foot were 

 fumigated, lenticel spotting appeared, but little or no eye injury; 

 but when the quantity of potatoes per cubic foot was reduced to 

 5 lbs. or less the injury was marked about both lenticels and eyes. 

 In the original fumigation, the 87 bushels of potatoes were treated 

 in a cellar containing 3,500 cubic feet, making only about 1^ lbs. 

 of potatoes to a cubic foot, an amount far below the minimum found 

 necessary, in the tests, to insure safety. 



At first thought this explanation appears a paradox; 

 Role of for it would seem that 12 lbs. of potatoes per cubic 



adsorption. foot would occupy much more of the room than two 



pounds, would crowd the gas into a smaller volume, 

 concentrate it and cause more rather than less injury. This would 

 be true were it not for a peculiar ability which many, if not all solid 

 bodies possess, to collect upon their surfaces large amounts of certain 

 gases. For example, boxwood charcoal will " adsorb " ninety times 

 its own volume of ammonia gas, fifty volumes of hydrogen sulphide 



