SOME EXPERIMENTS WITH DISINFECTANTS 7 



between the foot of the door and the floor. The two smaller rooms 

 measured 9 ft. by 7 ft. by 8 ft, and 8 ft. by 7 ft. by 8 ft. respectively, and 

 each had one small window but no fireplace. The total cubic space of 

 the main room and the two closets amounted to 2536 cubic feet. 



The object aimed at was the disinfection of the whole dwelling, the 

 apparatus being placed in the middle of the floor of the main room, 

 while the doors leading to the small rooms were left open. During the 

 experiment the four windows and the door were closed in the usual way, 

 without sealing, but the chimney was roughly stopped with paper. 



Technique. — Small blocks of unvarnished wood, each 4 in. long by 

 I J in. broad, and having a small oblong area marked on the surface, were 

 sterilized in an autoclave at a temperature of 120° C. for one hour. 



The following micro-organisms were used in the experiment : — 



1. an actively sporing culture of Bacillus anthracis. 



2. 24 hours' culture on agar of Staphylococcus pyogenes aureus. 



3. 24 hours' culture on agar of Bacillus coli communis. 



4. 24 hours' culture on agar of Bacillus typhosus. 



5. 24 hours' culture on serum of Bacillus diphtheriae. 



Emulsions of these different micro-organisms were made with 

 bouillon in sterile test glasses, and spread, by means of sterile brushes, 

 on the marked areas of the wooden blocks, and allowed to dry in air. 

 They were then distributed in the following places : — 



1. floor of the main room. 



2. the mantelshelf above fireplace of main room. 



3. ledge above window of main room. 



4. shelf, 7 feet from floor, directly opposite the apparatus. 



5. floor of one of the closets, in a corner remote from the door. 



In this experiment the blocks were protected from direct deposition 

 of the disinfectant by means of several loosely placed layers of brown 

 paper, and were exposed to the action of the vapours from the apparatus 

 for 3 hours. The marked areas on the wooden blocks were then scraped 

 by means of sterile chips of glass, and the scrapings were placed in 

 tubes of bouillon, and allowed to incubate for 7 days at a temperature of 

 37° C. Control blocks made at the time of doing the experiment were 

 treated in a similar way, except that they were not exposed to the 

 vapours. 



(243) R I 



