QUESTIONS 



191 



FIG. 109 



in the gaseous state in any form for the disinfection of the habitation 

 of man and domestic animals, all doors, windows, cracks, and openings 

 of any sort should be closed tight. In the case of barns, stables, etc., 

 this task is not always easily accomplished. The amount of formalin 

 necessary for the disinfection of any space depends upon its cubical 

 contents. Approximately a pint of 40 per cent, formalin or 60 pastilles 

 of paraform must be evaporated for each 1000 cubic feet of space. 

 With the Breslau method about J pint for 

 1000 cubic feet is sufficient in a seven 

 hours' exposure. Any formaldehyde re- 

 maining at the termination of disinfection 

 may be neutralized by ammonia vapors. 

 Formaldehyde is not an insecticide, and 

 has no effect on these animals. 



Sulphur Dioxide. Besides formaldehyde, 

 sulphur dioxide is the only other substance 

 which is still extensively used as a gaseous 

 disinfectant. It is produced by burning 

 sulphur. The simplest and best arrange- 

 ment is to place flowers of sulphur into 

 an iron pot, which is placed in a second 

 metal vessel containing a quantity of 

 water. This arrangement reduces the 

 danger of fire to a minimum, and by the 

 heating and boiling of the water which 

 will occur the amount of water vapor is 

 supplied necessary to convert the sulphur 

 dioxide into sulphurous acid, which is an 

 effective germicide. Sulphur dioxide, in 

 addition to destroying germs, also kills 

 insects and vermin, such as mice and 

 rats. Five pounds of sulphur should be 

 burned for each 1000 cubic feet of space, 

 and one pound of water should be vapor- 

 ized for each five pounds of sulphur. Spaces to be disinfected by 

 burning sulphur must, of course, be made as air-tight as possible. 



Alcohol. It should be remembered that absolute alcohol has prac- 

 tically no germicidal power. There is, however, considerable germi- 

 cidal value in 50 per cent, alcohol, and it is well adapted for use in 

 disinfecting surgeons' hands and the skin of animals before operations. 



Sanitary Construction Company's 

 regenerator. 



QUESTIONS. 



1. What is meant by infected objects? 



2. What does the term disinfection signify? 



3. Can pathogenic microorganisms be removed from water without destroying 

 them, and how? 



4. What means different in type can be employed for disinfecting purposes? 



