ON STAINING FLUIDS, AND STAINING. 107 



Asphalt Varnish. It is better to purchase 

 this also. Mr. Kitton, however, finds that asphalt 

 dissolved in benzol, and to which is added some 

 gold size, answers its purpose well. 



Qold Size. This, again, should be purchased, 

 as also should Marine Glue, which, as well as the 

 following cement, is used for affixing cells to slips. 



G-UTTA PEECHA CEMENT. (Harting's formula.) 



Divide gutta percha into small pieces, and dis- 

 solve it, by means of moderate heat, in 1 5 parts of 

 oil of turpentine ; when dissolved, strain it through 

 linen, and whilst the solution is kept at a gentle 

 heat, stir into it one part of shellac. 



For affixing cells to the slips, heat the cement, 

 make a ring on the slip the size of the cell, attach 

 the cell and heat the slip until the cell is affixed by 

 an even layer of the cement, so that no leakage may 

 occur. 



Shellac Cement or Varnish. Break up 

 shellac into very small flakes, and put these into 

 a bottle with strong methylated spirit ; shake it up 

 frequently, until there results a solution sufficiently 

 thick to be used easily with a brush. When from 

 keeping it becomes too thick, add more spirit. 



WHITE ZINC CEMENT. 

 (Walmsley's formula), and given by him to the author. 



In order to ensure that the white oxide of zinc 

 which is the foundation of this valuable and per- 

 manent cement shall be of the best quality, and 

 well ground, it is advisable to purchase a large tube 

 of artist's "zinc white," rather than to grind for 



