PRINCIPLES OF BACTERIOLOGY 



For the production of greater quantities of formaldehyde vapor several 

 of these outfits may be used together. The lamp is filled with ordinary 

 or wood alcohol, about twice as many cubic centimetres of the alcohol 

 being employed as there are pastilles to be evaporated. The wicks 

 should project but little above the necks of the burners, or the apparatus 

 may get too hot and ignite the pastilles. The vessel is charged with 

 formalin pastilles and the disinfector placed over the lighted spirit lamp. 

 The lamp is then allowed to burn out in the closed room. One hun- 

 dred pastilles are considered to be sufficient for the disinfection of 1000 

 cubic feet of space. Lately, a small steam boiler has been added to 

 the apparatus, for the purpose of furnishing sufficient moisture with 

 the gas. The results obtained by us in superficial disinfection, when 

 from 150 to 200 pastilles have been used to each 1000 cubic feet, have 

 been good. The great advantage of the method is in the small cost of 

 the apparatus, $3.00, and the avoidance of the danger of deterioration, 

 which is present to some extent in formalin. Smaller lamps are very 

 useful for the deodorization of rooms. 



From, Pastilles Composed of a Top of Compressed Paraform and a 

 Base of Prepared Charcoal. This is a very neat but somewhat expen- 

 sive method of liberating formaldehyde gas. Our results with it have 

 been good. 



Formalin to which Glycerin has been Added. To the formalin is added 

 10 per cent, of glycerin, and the mixture is simply boiled in a suitable 

 copper vessel, the steam and formaldehyde gas passing off by a tube. 

 This is a very serviceable apparatus. When it is attempted to vaporize 

 the formalin too rapidly part of it passes over in fluid form, and is thus 

 wasted. 



With a slightly greater amount of formalin than that used in the 

 high temperature autoclave and heated tube or chamber methods, the 

 results seem to be equally as good. The apparatus is very easy to use, 

 and is not liable to get out of order. 



Similar forms of apparatus are also employed, when instead of 

 glycerin the formalin is mixed with an equal quantity of water. The 

 water is for the purpose of giving additional moisture to the air, and, 

 at the same time, like the glycerin, to prevent the change of formal- 

 dehyde into inert substances. 



From Formalin in an Open Pan. A very simple method, devised 

 by Dr. R. J. Wilson, is to fill a tin pan with twelve ounces of formalin 

 for each 1000 cubic feet and put this on an upright sheet of tin, which is 

 cut so as to allow of the entrance of air below and yet protect the for- 

 malin in the pan from the flame. For heating put under it a small tin 

 can filled with asbestos packing which has been soaked with wood 

 alcohol. A still simpler method is to hang sheets in a room and throw 

 on them twelve ounces of formalin for each 1000 cubic feet, and leave 

 for ten hours. If the room is tightly sealed very fair superficial disin- 

 fection will take place. 



Lime Method of Generating Formaldehyde Gas. The use of quick- 

 lime for generating formaldehyde gas has been practised by various 



