ANTISEPTICS AND ANTISEPSIS 235 



Phenol in 5 per cent, solution will destroy most of the bac- 

 teria in less than five minutes. 



Formaldehyd^ in gaseous form or in a liquid spray, is a very 

 efficient germicide, and from the fact that it is not destructive 

 to fabrics or paper has come into general use as a disinfectant. 

 In combination with potassium permanganate or in suitable 

 generators it is employed in houses after infectious diseases. 

 It has no effect on insects, and where it is necessary to destroy 

 these, other agents, known as insecticides, must be used in con- 

 nection with the gas. The gas should be in a moist state from 

 6 to 1 6 ounces for an ordinary room are needed; the room 

 should be made as air-tight as possible, and the gas evolved as 

 speedily as possible. 



In the permanganate method 8 ounces (by weight) of 

 potassium permanganate crystals are placed in a large tin 

 vessel ten times the capacity of the disinfectant used. One 

 pint of formaldehyd solution is quickly poured over the 

 crystals. Formaldehyd gas is thereby generated at once. 

 This will produce enough gas for disinfection of 1000 cubic 

 feet. 



Sulphur dioxid, or sulphurous acid gas, is a germicide and 

 insecticide, and is much used in disinfecting after yellow fever 

 and malaria. It is obtained by burning sulphur in a pan over 

 water, and about i pound to a room is necessary. 



Alcohol, iodin, chlorin, potassium permanganate, hydrogen 

 dioxid, the salts of silver, lead, and zinc, salicylic acid, boric acid, 

 anilin dyes (methyl-violet and methylene-blue) , naphthalin, and 

 creosols are a few of the substances in use as antiseptics 

 and germicides in surgery. Their power varies with the 

 strength of the solution and all have limitations. 



In surgical operations more dependence is placed to-day 

 on securing and maintaining a germ-free or a septic condition 

 than on the attempt to destroy germ life by chemicals. The 

 irritation of antiseptics in some instances prevents the natural 

 defense forces (phagocytes) from acting, and in abdominal 

 operations, where no pus has been encountered, the blood- 

 serum or normal salt solution is alone used. 



