328 BACTERIA 



We may turn from these general principles to mention 

 shortly some of the types of steam disinfectors most com- 

 monly in use. They are four, namely, the Washington 

 Lyon, the Equifex (Defries), the Thresh, and the Reck. 



Washington Lyon s apparatus consists of an elongated 

 boiler having double walls, with a door at each end. The 

 body of the apparatus is jacketed. The whole is large 

 enough to admit of bedding and mattresses, and generally 

 is so arranged that one end opens into one room, and the 

 other end opens into another room. This convenient posi- 

 tion admits of inserting infected articles from one room and 

 receiving them disinfected into the other room. Possible 

 reinfection is thereby prevented. Steam is admitted into 

 the jacket at a pressure of between twenty and twenty-five 

 pounds, and is generally twenty pounds in the interior of 

 the cylinder. At the end of the operation a partial vacuum 

 is created, by which means much of the moisture on the 

 articles may be removed. In some cases a current of warm 

 air is admitted before disinfection in order to diminish the 

 extent of condensation. 



The Equifex (Defries) contains no steam jacket, but coils 

 of pipes are placed at the top and bottom of the apparatus, 

 with the object of imparting to the steam as much heat as 

 is lost by radiation through the walls of the disinfecting 

 chamber, and at the same time of preventing undue con- 

 densation. The air is first removed by a preliminary cur- 

 rent of steam, after which steam at a pressure of ten pounds 

 is intermittently introduced and allowed to escape. The 

 object of this proceeding is to remove air from the pores of 

 the articles to be disinfected by the sudden expansion of the 

 film of water previously condensed on their surface. The 

 apparatus introduced by Dr. Thresh was constructed with a 

 view of overcoming the objection to some of the other 

 machines that bulky articles retained a large percentage of 

 moisture, thus necessitating the use of some additional 



