190 Report of the Department of Botany of the 



and painted inside. On one side there was a hinged door 17 x 23 

 inches. In the first 30 experiments some leakage of gas occurred 

 around the door. Then the fittings of the door were tightened so 

 that in subsequent experiments (excepting No. 89) scarcely any odor 

 of escaping gas could be detected. During 22 of the experiments 

 (Nos. 31 to 37, 51 to 55 and 76 to 85) the box stood in the cement 

 cellar where the original injury occurred; during 43 experiments 

 (Nos. 1 to 30 and 38 to 50) it stood in the furnace room of a green- 

 house; during 21 experiments (Nos. 56 to 73 and 87 to 89) it stood 

 in an unheated barn where doors on opposite sides permitted a free 

 circulation of the outside air; during Experiments 74 and 86 it stood 

 in the open air; and in Experiment No. 75 under a shed open on 

 one side. In the first eleven experiments the humidity is unknown 

 and the temperature was not very accurately determined; but in 

 experiments subsequent to No. 11, and excepting Nos. 87-89, both 

 the humidity and the temperature were recorded by a Friez hygro- 

 thermograph 10 placed inside the box. The generator used was a 

 pint tin cup with flaring sides. In the first four experiments the 

 charge consisted of 14.06 grams of potassium permanganate and 30.6 

 cubic centimeters of formaldehyde solution. These quantities are 

 equivalent to 23 ounces of permanganate and three pints of 

 formaldehyde to 1000 cubic feet (Morse's formula), but as they 

 were found somewhat difficult of exact measurement we used, 

 instead, 14.25 grams KMn0 4 and 30 cubic centimeters CH 2 in 

 subsequent experiments. It will be observed that the ratio of 

 KMn0 4 to CH 2 is that recommended by Evans n and that the 

 quantity of formaldehyde solution used was equal to 1391.4 

 cubic centimeters (a trifle less than three pints 12 ) per 1000 cubic 

 feet. In all but three of the experiments the time of exposure 

 was 24 hours. The bulk of the potatoes were exposed in bushel 

 crates, but in addition there was invariably a check of 10 to 40 test 

 tubers spread upon the floor of the fumigation chamber. The test 

 tubers were thoroughly washed in order that any injury to them 

 might be readily detected. After treatment they were stored in a 



10 Kindly loaned by Dr. L. Knudson of the Department of Plant Physiology, New 



York State College of Agriculture. 

 "Evans, H. D. Disinfection bv the formalin-permanganate method. Me. State 



Bd. of Health Rpt. 14:227-249. 1906. 

 12 Three pints = 1419.45 cubic centimeters. 



