FORMULAE. 197 



MISCELLANEOUS FORMULAE. 



DAMMAR MOUNTING VARNISH. 



No. 1. 



Gum Dammar, 4 ounces. 



Gum Mastic (in "tears"), ... 2 " ' 



Spirits of Turpentine, .... 8 " 



Chloroform (Squibb's), .... 4 " 



Mix the dammar with about an equal bulk of clean broken glass. 

 Put in a wide-mouth bottle, and, having added the turpentine, set in 

 a warm place. The glass is added for the purpose of separating the 

 lumps of the resin, and thus hastening the solution. Stir the mixture 

 occasionally. 



Add the mastic to the chloroform in a well-stoppered bottle. 



When the solution of the resins is complete add the chloroform 

 mixture to the dammar, and keep in a bottle covered with a plate of 

 glass. After the dirt from the gum has thoroughly settled, decant 

 into small bottles for use. Do not attempt to filter. 



I have histological mounts which were made with this medium 

 nearly ten years since, and the tissues have shown no deterioration 

 whatever. 



DAMMAR MOUNTING VARNISH. 



No. 2. 



Bsst dammar varnish of the paint-shops, diluted with a sufficient 

 quantity of turpentine. 



I do not know that this is in any way inferior to the last, but histol- 

 ogists generally have a preference for media of known composition. 

 They may both be diluted with turpentine, chloroform, ether, or pure 

 benzole; or thickened, by removing the stopper of the bottle until a 

 sufficient amount of the solvent has evaporated. 



XYLOL BALSAM. 



Xylol is preferred by some histologists as a solvent or diluent of 

 Canada balsam for general mounting purposes. Xylol dissolves the 

 balsam very readily without heat, and evaporates more rapidly than 



