DISINFECTION 453 



faction is neglected, preventable diseases continue to 

 attack mankind. Some of the methods of disinfection 

 for particular diseases have already been suggested. 

 Thus, the sputum of a person having consumption or 

 pneumonia ought to be burned (cf. 429 and 436); the 

 cloths containing the discharges from the nose and throat 

 during scarlet fever and measles ought to be boiled in hot 

 water; dishes used by a patient, even if he has "only a 

 cold," ought to stand in boiling water for some minutes, 

 so that the germs adhering to them may be entirely 

 destroyed. The need of disinfecting the body waste of 

 typhoid patients has not yet been appreciated sufficiently; 

 it is through these wastes that water is polluted, and that 

 the disease is spread (cf. 427). Experience has taught 

 men that direct sunlight is an excellent germicide, hence 

 they have, from time immemorial, hung clothing and 

 bedding in the sunlight for disinfection. Of course a large 

 part of the disinfection that is carried out "in the open" 

 is due to air (cf. 58). Long-continued drying destroys 

 germs, as it does other living things. One way in which 

 salt acts as a preservative is that it removes water from 

 the cells of the germs that cause decay. Long-continued 

 cold also destroys germs ; strange as it may seem, explorers 

 in polar regions are not troubled with colds; the germs of 

 colds cannot live there. 



Substances having poisonous properties are also used to destroy 

 germs. One of the most frequently used of these chemical disin- 

 fectants is mercuric chloride. This is a compound of mercury and 

 chlorine; it is also known as bichloride of mercury and as corrosive 

 sublimate. It may be purchased in tablets that dissolve readily in 

 water. The " strength" of the solution is usually 1 part, by weight, 



