30 MEDICAL BACTERIOLOGY 



4. Clinical results have substantiated the estimate of the therapeutic value 

 of flavine." 



The following chart shows the antiseptic value of flavine and other substances, 

 as published by the same experimenters. 



GASEOUS DISINFECTION 



The best and most ideal way of disinfecting and destroying those agents 

 that produce disease is by the use of a suitable gaseous disinfectant. Rooms, 

 buildings and similar compartments could not, even with difficulty, have germi- 

 cidal solutions applied to them, for it would be hard to reach all surfaces and 

 then hold such solutions in contact for a sufficient length of time, in order to 

 obtain the desired bactericidal action. In addition, various substances would 

 be injured, if any but a gaseous disinfectant be used as a means of obtaining 

 sterility. 



The most practical and yet a suitable and efficient gas for general applica- 

 tion is formaldehyde. It is virtually non-poisonous, non-corrosive, non-in- 

 jurious to all substances, possesses no bleaching effect and still is very effective. 

 There are numerous methods of generating this gas, to be used in practical 

 operations; but this should be noted, when using any of the methods. 



Formaldehyde to be effective must be used in an environment, the tempera- 

 ture of which should not be below 6oF., a higher temperature is more preferable. 

 With the gas there should also be an evolution of water vapor, producing a 

 relative humidity of 70 per cent, or over. Unless the conditions be adhered to, 

 it is useless to attempt disinfection with formaldehyde, as otherwise the latter 

 will polymerize, precipitating a solid substance, commonly known as paraform 

 or paraformaldehyde. In all cases where formaldehyde disinfection is per- 

 formed, all cracks should be hermetically sealed (especially those of doors, 

 windows, etc.) and all drawers and cupboards, containing fabrics and all 

 apparel should be freely opened and the latter spread about to permit sufficient 

 exposure to the gas. 



One of the first methods of liberating formaldehyde gas was the method de- 

 vised by Trilatt, in which he directed the evaporation of the gas from a solution 

 of formalin (a 40 per cent, solution by weight of the gas in water) to which he 

 added from 1 5 to 20 per cent, of calcium chloride. Such mixture forms a prepara- 

 tion, commonly termed formochloral, which possesses the characteristic property 

 of practically eliminating polymerization. Glycerin has been suggested by 

 Schlossmann, in concentration of 10 per cent, as a substance replacing calcium 

 chloride and hindering polymerization. The apparatus used for the latter and 

 similar solutions consists of a generator, which permits the solution contained 

 therein, when heated, to flow in a fine stream through a copper coil heated to 

 redness by a flame, the gas vapor then passing directly into the room together 

 with some moisture in a superheated and effective condition. Such generators 

 can be operated outside the room to be disinfected. 



Similar to the latter and a most efficient method of disinfecting with for- 

 maldehyde is the generation of the gas within an autoclave set to blow off at 



