32 EXCLUDING MOISTURE FROM TEETH 



operation dry, has led to the adoption of various 

 expedients. Folds of blotting-paper, of linen rag, 

 of lint, and masses of cotton-wool, have been placed 

 on one or both sides of the tooth with more or less 

 success ; but it is always a struggle between the 

 operator and the accumulating saliva. The napkins 

 have to be changed when the operation is prolonged, 

 and all our efforts are not unfrequently rendered 

 futile by the fluid overflowing the unfinished plug 

 during the withdrawal of the wet and the substitu- 

 tion of the dry napkin. 



S3rringes, and even syphons, have been contrived 

 for the removal of the saliva, but their use has not 

 been attended with any great advantage. I have 

 heard a practitioner talk of building up a dam of 

 wax around the faulty tooth before commencing to 

 introduce the gold ; but in my hands the method 

 has altogether failed. 



Some time since it occurred to me that with a 

 membrane made very adhesive on the one side, and 

 perfectly water — or rather saliva — proof on the 

 other, we should be able to command a much greater 

 degree of success than is attainable by the means at 

 present in use. The first experiment was made by 

 coating the gutta-percha membrane of the shops 

 with a thin layer of gelatine ; and the first case in 

 which the new material was tried demonstrated the 

 success of the principle adopted. The tooth operated 

 upon was a second molar of the lower jaw, decayed 

 on the anterior surface. After the softened dentine 



