1899] MICROSCOPICAL JOURNAL. 361 



with a steam boiler and the generators communicate with 

 the disinfecting chamber by small pipes. 



METHOD OF OPERATING. 



Steam is turned into the jacket until a temperature of 

 at least 80° C is obtained within the chamber. The ar- 

 ticles to be disinfected are placed in the rack or car which 

 is rolled into the chamber, the door is closed and secured, 

 and a vacuum of 15 to 20 inches obtained. By this time, 

 steam having been allowed to course through the coil 

 within the generator containing the formalin mixture, 

 there should be a pressure of 40 to 60 pounds. The heat 

 in the chamber has been gradually increased, and the ther- 

 mometer should register nearly or quite 90° C. With 

 the above pressure and temperature, the valve between 

 the generator and chamber is opened just enough to per- 

 mit the escape of gas in sufficient quantity to cause the 

 pressure to gradually decrease. 



At the end of ten or fifteen minutes all the gas has 

 probably been expelled and the valve may now be closed. 

 Steam is kept slowly coursing through the jacket in order 

 to maintain a constant temperature of 90° C, or more. A 

 higher degree of heat, while doing no harm, does not ap- 

 pear to increase the efficiency of the formaldehyd, but it 

 is certainly diminished at a lower temperature. The 

 vacuum will usually fall seven or eight pounds, and pos- 

 sibly more, according to the quantity of gas entering the 

 chamber. At the end of one-half hour the vacuum may 

 be broken and air allowed to fill the chamber. This mix- 

 ture of air and formaldehyd is then exhausted, and the 

 a mm ia generator, previously supplied with aqua am- 

 nion one half as much as of formalin, is operated in the 

 manner as already described for formaldehyd; the latte r 

 having been in a great measure removed with the air, a 

 a small quantity of ammonia will neutralize the residue. 

 Air is again allowed to enter the chamber and the door 

 may now be opened. It is usually found that there is a 



