BIOLOGY. 249 



hood won the prize at the Olympic games ever distinguished 

 himself afterward. The 3 years immediately preceding 17 are 

 years of great mental development, and nature cannot at the 

 same time endure any severe taxing of the physical constitution. 

 Prudence, therefore, especially at this critical period of life, must 

 ever go hand in hand with vigor, for the evils of excess outweigh 

 by far the evils of deficiency." 



DISINFECTANTS. 



Dr. Letheby, Health Officer of the city of London, has recently 

 made the following report. 



The several disinfectants which I have largely tested are the 

 following : 



1. Chlorine gas. 



2. Chloride of lime. 



3. Carbolate of lime. 



4. Carbolic acid. 



5. Chloride of zinc (Sir William Burnett's fluid). 



6. Chloride of iron. 



7. Permanganate of potash (Condy's liquid). 



8. Animal charcoal. 



Each of these disinfectants has its own particular value, and 

 may be used on certain occasions in preference to any of the 

 others. Thus : 



1. Chlorine Gas, being a very diffusive body, is best suited for 

 the disinfection of places which cannot easily be reached by other 

 disinfectants. I have used it largely for the disinfection of the vaults 

 of churches, where the atmosphere has been so charged with of- 

 fensive and dangerous organic vapors, let loose from the contents 

 of the decaying coffins, that the workmen could not entei v the vaults 

 with safety. In this manner all the vaults of the city churches 

 have been'disinfected, and the contents of them put in order and 

 covered with fresh mould. I have found also that chlorine is best 

 suited for the disinfection of rooms where, as is the case with the 

 poor generally, the occupant cannot be removed for a thorough 

 cleansing; and I have employed it with great advantage in places 

 where persons have been sick with fever, scarlet fever, small-pox, 

 and cholera. The process which I adopt is the following: 

 About a teaspoonful of the black oxide of manganese is put into a 

 teacup, and there is poured over it, little by little, as occasion re- 

 quires, about half a teacupful of strong muriatic acid (spirit of 

 salt). In this manner the chlorine is gradually evolved, and the 

 action is increased, when necessary, by stirring the mixture, or 

 by putting the teacup upon a hot brick. As chlorine is heavier 

 than atmospheric air, it is best diffused through the room by put- 

 ting the mixture upon a high shelf. The quantity of chlorine thus 

 diffused should never be sufficient to cause irritation to the lungs 

 of those who occupy the room, and yet it should be sufficient to 

 be distinctly recognizable by its odor. If it be properly managed, 

 the chlorine may be thus diffused through the atmosphere of the 

 room, even during its occupation by the sick. 



