ORGANIC COMPOUNDS 145 



excludes them from practical use, except that "lye washes" 

 are of value in cleaning floors and rough woodwork, but 

 even here better disinfection can be done more easily and 

 safelv. 



Fig. 103. — Tanks for bichloride of mercury, government quarantine 

 disinfecting plant. 



ORGANIC COMPOUNDS. 



Carbolic Acid or Phenol.— Carbolic acid or phenol (CeHsOH) 

 is one of the commonest agents in this class. It is used 

 mostly in 5 per cent solution as a disinfectant and in 0.5 

 per cent solution as an antiseptic. For use in large quanti- 

 ties the crude is much cheaper and, according to some experi- 

 menters, even more active than the pure acid, owing to the 

 cresols it contains. The crude acid is commonly mixed with 

 an equal volume of commercial sulphuric acid and the mix- 

 ture is added to enough water to make a 5 per cent dilution, 

 which is stronger than either of the ingredients alone in 5 

 per cent solution. 



Cresols.— The cresols (C6H4CH3OH, ortho, meta and 

 para), coal-tar derivatives, as phenol, are apparently more 

 powerful disinfectants. A great number of preparations 

 10 



