438 DISINFECTION 



the other room. Possible reinfection is thereby removed. Steam 

 is admitted into the jacket at a pressure of between 20 and 25 

 Ibs., and its penetrating power may be increased by intermitting 

 the pressure during the disinfection. 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 pre- 

 venting undue condensation, and to be available for drying. The air 

 is first removed by a preliminary current of steam, after which steam 

 at a pressure of 10 Ibs. is intermittently introduced (for about 

 five minutes), 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 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 necessi- 

 tating the use of some additional drying apparatus. A central 

 chamber receives the articles to be disinfected, and is surrounded by 

 a boiler containing a solution of calcium chloride (carbonate of potash 

 is now used) at a temperature of 225 F. This is heated by a small 

 furnace, and the steam given off is conducted into the central 

 chamber. Owing to the dissolved potash the temperature of the 

 steam given off when the solution boils is several degrees higher than 

 ordinary steam. The steam is not confined under any pressure 

 except that of the atmosphere. When the steam has passed for a 

 sufficient length of time, it is readily diverted into the open air. Hot 

 air is now introduced, and at the expiration of an hour the articles 

 may be taken out disinfected and as dry as they were when inserted. 

 The apparatus is comparatively inexpensive, and not of a complicated 

 nature. The current steam is saturated, and at a temperature a few 

 degrees above the boiling-point. The apparatus is now made in 

 various forms, portable or otherwise. 



There are many other forms of steam disinfector, including the 

 apparatus by G-oddard, Massey, and Warner, the disinfector of Dele- 

 pine, and that of Eeck and others, and each has its enthusiastic 

 supporters. 



