SOME EXPERIMENTS WITH DISINFECTANTS 5 



recommended that the room to be disinfected should be heated by 

 artificial means, high degrees of heat aiding the disinfectant powers of 

 the gas. A certain amount of moisture has also been found to be 

 essential to successful gaseous disinfection, and the maximum dis- 

 infecting power is got only if the atmosphere be saturated with moisture. 

 H. W. Hill states that an amount of gas which failed to kill in 6 hours at 

 42 per cent, humidity, killed in 20 to 40 minutes at 100 per cent. 

 Another important requirement is that the gas be evolved rapidly, so as 

 to obtain a sufficient concentration of the gas in the room at one time. 

 Rideal, in his experiments with Thursfield's lamp, found that a larger 

 amount of the disinfectant rapidly evolved is of greater value than 

 prolonged exposure to a smaller quantity of the gas. 



Many methods have been given as the most reliable for fumigation 

 with formaldehyde gas. For this investigation three methods were 

 chosen, viz. : — 



1. Lingner's apparatus, as representing the method of gaseous 



disinfection with the atmosphere saturated with moisture. 



2. The " Alformant" Lamp, where the method is dependent on the 



natural humidity of the atmosphere at the time of the 

 experiment. 



3. The Permanganate Process, as recommended by the Sanitary 



Authorities of the State of Maine, U.S.A. 



1. — Lingner's Disinfecting Apparatus. 



This apparatus, which is made in Germany, consists of a ring boiler 

 in which steam is generated and driven into a reservoir filled with 

 formaline or glyco-formol (30 per cent, formaldehyde with 10 per cent, 

 glycerine). By the pressure of the steam the formaline is ejected in the 

 form of a fine and very abundant spray through four separate nozzles 

 out of the reservoir. Two litres of glyco-formol are recommended as 

 sufficient for a room of 2800 cubic feet capacity. The addition of glycerine 

 is supposed (i) to hinder polymerization, (2) to hinder evaporation of the 

 formaline after deposition in the room, (3) to thicken the solution and 

 favour its adhesion to a smooth surface and its absorption by pores, in 

 consequence of which its effect is believed to be enhanced. The 



(241) R 



