QEttEfcAL fcACTEktOLOGY 
47 
Alcohol.—Alcohol is an efficient germicide but only 
in dilute solutions, the strongest germicidal action be¬ 
ing exerted by 50 to 70 per cent solutions; those stronger 
than this are much less efficient, the absolute alcohol 
being practically without any effects. 
Iodoform.—Iodoform is a weak germicide in itself, 
but when introduced into wounds, iodine is liberated 
and it is then a very efficient agent. 
Carbolic Acid.—Carbolic acid (phenol) and its de¬ 
rivatives—lysol, cresol, tricresol, creoline, etc., are very 
efficient germicides, especially the latter; they are not 
only germicidal but are also poisonous for human tis¬ 
sues; for this reason they should not be applied to 
wounds in solutions stronger than y ^-1 per cent nor 
should they be left for any length of time, as gangrene 
is a common result of their prolonged application. They 
are the best agents for disinfecting feces, urine, sputum, 
soiled linen, etc., for which purpose a 5 per cent solu¬ 
tion should be used. 
Boric Acid.—Boric acid is not a germicide but an 
antiseptic, that is, it does not destroy the bacteria but 
prevents their development; it is used upon mucous 
membranes and in the eye. 
Formaldehyde.—Formaldehyde is used either as a 
gas for fumigation or a 40 per cent solution in water 
(“formalin”); in the latter form it is an excellent sub¬ 
stance to be used for sputum, urine, feces, etc., in 
solution 2 to 5 per cent. For the use of formaldehyde 
in fumigation see the next section. 
Sulphur.—Sulphur is used chiefly for destroying the 
insects. 
III. Practical Disinfection 
Sputum is a very difficult thing to disinfect because 
the bacteria contained in it are protected by a thick 
