206 Report of the Department of Botany of the 



The following statement by Base 34 appears in his report on the 

 chemical work done in connection with McClintic's investigation: 

 " M. B. Porch (Assistant in Pharmacology, Hygienic Laboratory, 

 Washington), using the same apparatus and methods that I did, 

 but working at lower temperatures, found that polymerization of 

 formaldehyde gas begins at about 62 degrees Fahr., and becomes 

 more marked as the temperature decreases, which is evidenced by 

 the persistent hazy condition of the air of the room, the low per- 

 centage yield of formaldehyde, and the deposition of paraformalde- 

 hyde in the room. He obtained in the permanganate-formalin 

 method a yield of 25.1 per ct. at 62 degrees Fahr. and 11.1 per ct. 

 at 52 degrees Fahr., as against 38.39 per ct. obtained by me at the 

 higher temperatures of my experiments, namely, 71 degrees and 79 

 degrees Fahr." 



According to Rosenau 35 " the action of the gas seems to be 

 about the same between the temperatures of 10 degrees C. and 27 

 degrees C. Higher degrees of heat materially aid the disinfecting 

 power of the gas." 



Discussing the disinfection of seed potatoes Morse says: 36 " Tem- 

 perature is an important factor in disinfecting with formaldehyde. 

 It is more effective above 80 degrees Fahr. and disinfection with 

 this gas should never be attempted where the temperature of the 

 chamber used is below 50 degrees Fahr." 



In 21 of our experiments the temperature was at or below 50 

 degrees Fahr. and in two of them below 40 degrees Fahr. ; yet more 

 or less injury occurred in 16 of these experiments, being quite severe 

 in some of them. Even in Experiment 32, in which the maximum 

 temperature was 39 degrees Fahr., fully one-half the eyes on the 

 tubers were ruined. Most of the experiments were conducted at 

 temperatures of 50 to 70 degrees Fahr. ; temperatures higher than 

 70 degrees were had in only two experiments, viz. No. 3 in which 

 the maximum temperature was 72 degrees and in No. 74 in which 

 it was 87 degrees Fahr. We were able to obtain the high tem- 

 perature of 87 degrees only by placing the disinfection chamber 



34 Base, Daniel. Formaldehyde disinfection. Determination of the yield of for- 



maldehyde in various methods of liberating the gas for the disinfection of rooms. 

 Jour. Am. Chem. Soc. 28 : 989. 1906. 



35 Rosenau, M. J. Disinfection and disinfectants, p. 90. P. Blakiston's Son & Co. 



Philadelphia. 1902. 



36 Me. Sta. Bui. 174:325. 



