ON MOUNTING OBJECTS. Ill 



that are quite obliterated with the balsam, are beautifully 

 shown in this medium." 



Glycerine was introduced by Mr. Warington, as a pre- 

 servative fluid for mounting organic substances in. The 

 method adopted by him in the employment of glycerine, 

 is simply to mount the object in the manner it is usually 

 performed when spirit of wine or creosote-water is used as 

 a medium, and having covered the immersed object with 

 the thin glass, and removed all excess of liquid, to cement 

 the margin with a coating of shell-lac varnish; the one 

 usually employed consists of the ordinary black sealing- 

 wax dissolved in rectified spirit of wine. Care must be 

 taken during this operation to maintain the slider in a flat 

 position, until the varnish has become dry from the eva- 

 poration of the spirit, and also until a sufficient number 

 of coatings or layers of the varnish have been applied to 

 render the subject perfectly secure, and prevent any escape 

 of the fluid. Gold-size or copal dissolved in oil of lavender 

 may be employed to effect the same purpose ; and the 

 second and third coatings may, with advantage, consist of 

 either of these, which yield a tough varnish above the lac, 

 which is otherwise liable to become brittle. 



The glycerine may be used in its concentrated form or 

 treacly state, or it may be diluted with distilled water to 

 any required extent, according to the object of the operator, 

 and the subject to be mounted : if there be extremely 

 fine markings on the subject, it is better to add about four 

 or five times its volume of water, as otherwise the thick 

 fluid may prevent these from being so sharply defined as 

 may be desired. 



" I have," adds Mr. Warington, " a number of slides of 

 Desmidiece, which have been mounted from four to ten 

 months by this means, and they have kept excellently. 

 The glycerine may also be used with the addition of a 

 small portion of culinary salt, corrosive sublimate, creosote, 

 or spirit of wine, if considered desirable." 



Glycerine and gelatine combined in certain proportions 

 makes an excellent mounting material; it should be so 

 mixed as to permit of its complete solidification, without 

 liability to crack when cold and dry. 



Castor-oil may be used as a medium for mounting 



