STERII.I/ATloN. 7 



The mechanism, by which the inner and outer chambers are con- 

 nected and disconnected, and that for vacuum production, rest in the 

 simple turning of a lever from mark to mark. We have been able 

 with a gas burner to obtain a pressure of fifteen pounds in less than ten 

 minutes. In sterilizing test-tubes we place them in small rectangular 

 wire baskets, 6x5x4 ins. These baskets are to be preferred to round 

 ones, as they pack more satisfactorily in the refrigerator used for storing 

 media. In sterilizing flasks, test-tubes, Petri dishes, throat swabs, 

 pipettes, etc., it has been our custom, after exposing to 20 pound- for 

 twenty minutes, to produce a vacuum for two or three minutes; then 

 with the steam in the outer jacket for a few minutes to thoroughly dry 

 the articles in the disinfecting chamber. The valve to the inner 

 chamber is then opened to break the vacuum; the door is now opened, 

 and the articles removed in as dry a state as if they had been in the 

 hot-air sterilizer. 



PRESSURE AND TEMPERATURE TABLE. 



5 pounds' pressure, 107.7 C., 226 F. 



10 pounds' pressure, 115. 5 C., 240 F. 



15 pounds' pressure, 121. 6 C., 250 F. 



20 pounds' pressure, 126. 6 C., 260 F. 



25 pounds' pressure, 130.5 C., 267 F. 



30 pounds' pressure, 134.4 C., 274 F. 



All such articles as Petri dishes, pipettes, swabs, etc. are wrapped in 

 cheap quality filter-paper, making a fold and turning in the ends as is 

 done in a druggist's package. Old newspapers answer well for this 

 purpose. The sterile swab can be used for many purposes in the 

 laboratory. They are most easily made by taking a piece of copper 

 wire about eight inches long, flattening one end with a stroke of a 

 hammer, then twisting a small pledget of plain absorbent cotton 

 around the flattened end. After wrapping, the swabs are sterilized in 

 bunches. We not only use them for getting throat cultures, but in 

 addition for culturing faeces, pus or other such material. The pus is 

 obtained with a swab, which material is then distributed in a tube of 

 sterile bouillon or water. With the same swab the surface of an agar 

 plate is successively stroked. This method is equally as satisfactory as 



