MISCELLANEOUS 215 



tains phenol, cresol, guaiacol, C,H^(0CH3)0H, and creosol, 

 0,H3(CH3)OCH30H. 



" Formalin^' the commercial name for a 40 per cent solution 

 of formaldehyde, HjCO, in water, is a very powerful disin- 

 fectant. Formaldehyde is a gas, and from strong solutions, 

 if exposed, it escapes into the air. A solution of 1 part of 

 this substance in 10,000 of water will prevent the growth 

 of many micro-organisms, while 1 in 100 gives absolute 

 sterility. 



Formalin is too expensive to be used for true disinfecting 

 purposes, but is largely used for the prevention of decay in 

 food materials. 



The above, though used in the liquid or solid form, are 

 volatile, and to some extent exert a disinfecting action upon 

 substances near but not actually in contact with them. 



The following substances, used as disinfectants, are non- 

 volatile, and only affect those substances with which they 

 or their solutions actually come into contact : 



Potassium Permanganate, KMqO^, or the sodium salt, 

 NaMnO^, and the manganates — e.g., KjMnO^ — are extremely 

 powerful oxidising agents, and soon destroy organic matter and 

 micro-organisms. Solutions of these salts are the active ingre* 

 dients in " Condy's Fluid." 



Zinc Chloride, ZnCl,, is a caustic and deliquescent solid. A 

 strong solution (about 50 per cent.) constitutes " Bur- 

 nett's Disinfecting Fluid," and is often used as a wood-preser- 

 vative. 



Copper Sulphate, "blue vitriol," or "blue-stone," CuSO^.SIIjO, 

 is sometimes used as a disinfectant, but is somewhat expensive. 



Mercuric Chloride, " corrosive sublimate," HgClj, is a very 

 efficient disinfectant, but is very poisonous. It is largely 

 employed in surgical operations. 



As antiseptics, several substances, in addition to those 

 described under " Disinfectants," are employed : 



Boinc Acid, or Boracic Acid, II3BO3, is a sparingly soluble, 

 crystalline, solid substance, almost devoid of taste. It is often 



