ON MOUNTING OBJECTS. 81 



6 ounces by weight ; honey 9 ounces by weight ; add a little spirits of 

 wine and a few drops of creosote ; mix and filter whilst hot, to render 

 perfectly clear. Or take of pure glycerine, 4 fluid ounces ; distilled 

 water, 2 fluid ounces ; gelatine, 1 ounce by weight ; dissolve the gela- 

 tine in the water made hot, then add the glycerine and mix with care ; 

 this need not be filtered. 



Fresh animal or vegetable structures containing their natural 

 juices require little or no preparation before mounting in this sub- 

 stance. Those contained in water, as the desmidiese, Crustacea, &c. 

 may, when taken out of their native element, be placed on a proper 

 slip of glass previously warmed, the superfluous water removed with 

 blotting-paper, and then mounted at once by dropping a little warm 

 medium upon them and covering with thin glass. Animalcules 

 mounted in this way do not appear to alter either in colour or di- 

 mensions. The latter may be accounted for in this way, viz. that 

 the contraction of the medium is entirely in thickness, and the pres- 

 sure of the cover prevents any alteration taking place in the object 

 laterally. 



It is probable that some animalcules may be better shown if some 

 moisture be allowed to remain in the medium, the evaporation from 

 which may be stopped at any stage by filling round the edge of the 

 cover with some gold-size varnish, or even boiled linseed-oil. 



For many delicate objects this has a great advantage over Canada 

 balsam, in not possessing the high refractive power of that substance ; 

 and the minute hairs and other parts of insects, that are quite oblite- 

 rated with the balsam, are beautifully shown in this medium." 



Glycerine was introduced by Mr. Warington, as a preservative 

 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 dis- 

 solved in oil of lavender may be employed to efiiect the same purpose ; 

 and the second and third coatings may, with advantage, consist of 



G 



