STERILIZATION 3 1 



45 pounds pressure. The apparatus is set up outside the room or compartment 

 to be treated and a hose attached to the autoclave delivers formaldehyde-laden 

 steam through an opening. 



Blankets or sheets immersed and saturated with a solution of formalin have 

 been recommended to be hung in and about the room to be disinfected, to allow 

 the liberation of the gas by the heat present. To displace this, some have pro- 

 posed spraying the room with formalin from a compressed-air or steam atomizer. 

 Neither of these methods is certain as to the liberation of gas and the operator 

 must be careful and work rapidly, as formalin is irritating to the conjunctiva 

 and other mucous membranes. 



A most efficient and convenient method used is the liberation of the gas 

 within the room to be disinfected. The method used with universal approval 

 is the permanganate method. Potassium permanganate when mixed with 

 formalin results in an active reaction with the evolution of heat, which in turn 

 causes the evaporation of formaldehyde gas together with water vapor. While 

 some of the gas is actually consumed in the violent reaction, the yield is more 

 than by other methods and preferable because of the quick and sudden evolution 

 of all the gas, together with some moisture. 



In practice, i quart of formalin is poured over i pound of permanganate 

 crystals, using such proportions for each 1000 cubic feet of space. The operator 

 must be cautioned not to throw the permanganate into the formalin, for an 

 explosion will result. On account of the vigorous ebullition and foaming that 

 takes place, high cylindrical vessels should be used, about 10 or 12 inches in 

 height, which possess flared or funnel-like tops, so as to further assure any of 

 the sputtered material from being thrown out. A small lo-quart milk pail 

 answers well for such a purpose. 



Numerous modifications have been attempted recently to use other chemicals 

 instead of the permanganate salt. Potassium and more recently sodium dichro- 

 mate have replaced the latter, due to the cheapness in cost of material. Others 

 have used lime or quicklime, in which method the gas was generated by pouring 

 i pint of the solution of formalin over quicklime (from J^ to i% pounds) con- 

 tained in a wide shallow pan, placed in a basin of water. 



The dangers and inconveniences experienced with the foregoing methods 

 may be avoided if we use the " so-called" formaldehyde candles or other forms 

 of solid formaldehyde, as the source from which to obtain the gas. The Sherring 

 lamp was the first apparatus, in which solid formaldehyde or paraform was used 

 as a means from which to generate the gas. Heat was obtained from the igni- 

 tion of alcohol, which in turn decomposed the paraformaldehyde, liberating 

 gaseous formaldehyde. A temperature of at least 275?. is required for the 

 active generation of this gas from paraform. 



All other forms of solid formaldehyde and paraform candles are used the 

 same way, by applying heat to these substances, contained in metal receptacles. 

 Two ounces of paraformaldehyde generates sufficient gas to insure efficient 

 disinfection of a room having a capacity of 1000 cubic feet. 



Numerous suitable cabinets have been recently made and are in use by 



