ii6 



OPERATIVE TECHNIQUE. 



of the energetic way in which it removes water from living tissues 

 and coagulates albumen. It produces a hard black scab, which 

 remains in position a very long time. 



Fuming nitric acid produces a yellow scab, which is at first softer 

 than that produced by sulphuric acid, but. later becomes dry and hard. 

 The yellow colour is due to the formation of xanthoproteic acid, a 

 combination of nitric acid with albumen. 



Hydrochloric, carbolic, and chromic acids act less powerfully 

 than nitric or sulphuric acid. 



Among solid agents, caustic potash exercises a very marked and 

 penetrating action. It can be applied solid or in solution. Sticks of 

 fused caustic are to be preferred. The point is pressed on the part 

 to be cauterised until the intended amount of action has been 

 produced. Caustic potash, like some caustics previously mentioned, 

 acts by abstracting moisture from the tissues. It forms a greyish- 

 yellow scab sometimes mixed with blood. /\s this scab readily 



Fu;. 144. — Line firing iron and handle (interchangeable). 



breaks down and becomes fluid, the surrounding parts must be 

 carefully protected from its effects. A special caustic is used in 

 Vienna, consisting of six parts of caustic lime and five of caustic 

 potash moistened with alcohol to form a paste, which can then be 

 applied to the skin to the extent required. This paste does not run 

 or spread. 



Sublimate (bichloride of mercury) is also a powerful caustic. It 

 destroys tissues by combining with their albumen, and forms a soft 

 grey scab, which afterwards darkens and slowly separates. Sublimate is 

 employed as a powder, paste, or solution. Sublimate collodion con- 

 sists of five parts sublimate dissolved in thirty parts of collodion. 



Arsenious acid, or white arsenic, is usually employed in the form of 

 paste. The action is slow, the scab firm and durable. 



Chloride of antimony, otherwise known as butter of antimony, has 

 a powerful action, and produces a whitish, at first soft and afterwards 

 hard, sharply defined scab. 



