160 HYDROGEN PEROXIDE 



skin and mucous surfaces ; injected under the skin it 

 decomposes, with liberation of oxygen, producing subcutane- 

 ous emphysema. Intravenous injections are said to be 

 anaesthetic. It has no action on soluble ferments, but it 

 destroys organised ferments. It is of great value in the 

 treatment of suppurating wounds, abscesses, fistulae or 

 sinuses. In contact with blood or pus it decomposes with 

 effervescence, a reaction that is sometimes useful in diagnosis. 

 Injections of three per cent, solution of perhydrol may be 

 employed in retention of foetal membranes, in vaginitis and 

 metritis, and impaction of the facial sinuses. Peroxide 

 solution is also used as a disinfectant for abscess cavities and 

 to facilitate the removal of clinging wound dressings. As a 

 haemostatic, undiluted commercial peroxide or a solution of 

 one part perhydrol in ten parts of physiological salt solution 

 may be used. Perhydrol diluted with nine times its weight of 

 boiled water has been employed as a substitute for a 1:1000 

 mercuric chloride solution in the treatment of suppurating 

 joints, tendon sheaths, and compound fractures. A solu- 

 tion (one to three per cent.) may be used as an udder injec- 

 tion, an ounce for each quarter, in parturient toxaemia and 

 contagious mammitis, and as a spray for keratitis and corneal 

 ulcer. 



Internally, solutions of peroxide (one or two per cent.) have 

 been administered in dyspepsia, diarrhoea, and gastro- 

 intestinal catarrh. Peroxide is incompatible with perman- 

 ganates, charcoal, chromic acid, and mercuric chloride. 

 Caution is required in injecting peroxide in quantity into 

 large wounds, serous and other cavities, as it is quickly 

 decomposed ; and ' if more oxygen is formed than the blood 

 can dispose of, gas emboli are produced, and these lodging in 

 the lungs or brain may cause death. 5 (Hale White.) 



Doses (hydrogen peroxide 10 vols. per cent.). Horses and 

 cattle, gj. to gij. ; dogs, 3j. to 3ij. 



SALT ACTION-THE IONIC THEORY 



OSMOSIS. If two solutions of a salt of different strengths, 

 say sodium chloride, are separated by an animal membrane, 

 water will pass through the membrane from the less con- 



