New York Agricultural Experiment Station. 205 



treatment is more effective upon dry potatoes than upon wet ones. 

 From our own experiments it appears that wetting the tubers in- 

 creases rather than diminishes the liability of the tubers to injury. 

 In Experiments 1, 2, 3 and 44 some of the test tubers were dry and 

 others wet. In Experiment 44 both lots of tubers were severely 

 injured (completely ruined) without any appreciable difference 

 between the wet and the dry ones; but in the other three experiments 

 the wet tubers showed decidedly more injury than the dry ones. 

 It is also worthy of note that of the six experiments in which the 

 quantity of potatoes was 4 lbs. per cubic foot the greatest amount of 

 injury occurred in No. 84 the only one in which the test tubers 

 were wet. However, the humidity was somewhat higher in this 

 experiment than in any of the others. 



In the practical disinfection of seed potatoes the wetting of the 

 tubers is liable to be encountered, sometimes, in an unexpected 

 and annoying manner. Objects transferred from a cool room into 

 warm moist air quickly condense moisture upon their surface and 

 become quite wet. This happens to potatoes when removed from 

 a cool cellar to the warmer air of the disinfection room. 



TEMPERATURE. 



Although it is stated by Dudley and McDonnell 30 " that we are 

 fairly safe in ignoring temperature in the matter of disinfection 

 with formaldehyde down to as low, at least, as 32 degrees Fahr." 

 it is generally held that a moderately high temperature (60 degrees 

 Fahr. or more) is essential to thorough disinfection. 31 At lower 

 temperatures a portion of the formaldehyde becomes polymerized, 

 that is, changed into an amorphous white substance called para- 

 formaldehyde which is believed to be useless for purposes of dis- 

 infection. McClintic 32 says: " The effects of temperature seem to be 

 principally upon the state of the formaldehyde after it is liberated; 

 that is, below a certain point it polymerizes." In one of his experi- 

 ments in sleeping cars "ata temperature of 46 degrees Fahr. poly- 

 merization was so marked that the deposit of paraform gave the 

 interior furnishings of the car a frosty appearance." 33 



30 Loc. cit., page 8. 



31 A review of the early literature of this subject is given by Mayer and Wolpert. 

 Zur Rolle der Lufttemperature bei der Formaldehyddesinfektion. Hyg. Rund- 

 schau 11 : 396-400. 1901. 



i2 Loc. cit., page 110. 



n Loc. cit., page 91. 



