118 ON SOME OF THE CAUSTICS 



it can be safely applied on flat surfaces, where 

 arsenic, by escaping and lodging abont the mu- 

 cous membrane, might cause extensive ulceration ; 

 and there is no liability to injury of the adjacent 

 tissues by ulceration. On the other hand, arsenic 

 is more certain in its effect, and in most cases 

 does not cause such severe pain as does the zinc. 



Nitrate of silver is frequently used in stick or 

 in solution, to diminish the sensibility of dentine, 

 especially when that occurs after filing ; but it is 

 not so effectual as chloride of zinc. When placed 

 in the cavity of decay of a tooth, it gives rise to 

 discoloration very difficult to remove. 



The actual cautery has lately been employed by 

 dentists — ^by Mr. Waite, Mr. Harding, and others 

 — with the view to remove the tenderness of ex- 

 posed dentine. I have no experience of its avail- 

 ability for this purpose ; but its good qualities are 

 highly spoken of by these gentlemen. 



We will now proceed to consider, — 



2nd. Those cases where the pulp is exposed, and 

 is either to be entirely destroyed or brought into 

 a condition to bear further operations. 



The caustics most commonly used in this class 

 of cases are nitric acid, arsenious acid, chloride of 

 antimony, and the actual cautery. 



The two latter are those employed for the 

 purpose of inducing a healthy surface to an ex- 

 posed pulp, where it is deemed advisable to 

 endeavour to preserve that organ. The chloride 



