1899] MICROSCOPICAL JOURNAL. 365 



reason the water of the formalin should not be increased 

 in actual work. These three series are a proof, if any is 

 necessary, that the germicidal effects in the preceding 

 series were due to the formaldehyd, the heat acting mere- 

 ly as an intensifier. 



This cylinder had a capacity of 1,680 liters. The ratio 

 of 1,000: 1,680 is rather more than 1:2; that 750: 1,680 is 

 something less than 1:2; that of 500: 1,680 is about 1:3 ; 

 while that of 360 : 1,680 is a trifle more than 1:5. Once 

 the capacity of the chamber in which the work is to be 

 performed is known the proper quantity of the mixture 

 required is already determined. Formaldehyd is not re- 

 commended even when combined with a high degree of 

 heat, as a diginfecting agent upon which reliance can al- 

 ways be placed for the treatment of articles requiring 

 much penetration, especially when the exposure is limit- 

 ed to one-half hour. In twelve series the quantity of for- 

 malin mixture varied from 360 c. c. to 1,000 c. c, or tak- 

 ing the ratio given, from 1:5 to 1:2 mattress and pillows 

 were sterilized ; but in two series in which the propor- 

 tion of the mixture was as 1:5 the mattresses and pillows 

 were not penetrated. A critical examination of nearly all 

 the published experiments with this agent will reveal in- 

 stances in which organisms that there was every reason 

 to expect would be killed have survived, and vice versa. 

 It is that occasional unaccountable uncertainty of action 

 that calls forth the warning not to attempt disinfection 

 with formaldehyd in a case in which there is any doubt 

 as to the result. 



Care must be taken to arrange the various articles in 

 such a manner that a free circulation is allowed around 

 and among them. If the contents of a trunk were thrown 

 into the chamber in a heap it would not be penetrated. 

 The articles which can be treated successfully will be 

 found in practice to be wearing apparel, books, letters 

 and such other things as do not require deep penetration, 



