MOUNTING AND PRESERVING OBJECTS. 63 



4*. 



carefully managed, and the balsam itself be very fluid to com- 

 mence with. It should be sufficiently warmed to expel all air- 

 bubbles, and, when nearly cold, the object should be placed 

 in it and covered in the usual way. By pursuing this plan 

 (for which, with many other suggestions, I am indebted to 

 Mr. Quekett's admirable work on the Microscope), I have suc- 

 ceeded in making some excellent preparations at the expense of 

 but little time and trouble. Some operators, after covering 

 the object with balsam, if it is one that heat is likely to injure, 

 as an injected specimen, &c., leave the slide for a day or two, to 

 allow the air-bubbles to escape before putting on the glass 

 cover. But by careful management, the plan above referred 

 to will serve the purpose more readily. 



If the heat applied to the slide be great, the object will be 

 sure to curl up, and bubbles will appear in all parts. It will 

 most likely be rendered useless, as no manipulation, however 

 carefully applied, will restore an overheated specimen of animal 

 structure to its former beauty. 



After the slide has been prepared as above, the superfluous 

 balsam may be removed with the point of a knife previously 

 warmed in the flame of a spirit-lamp, &c. The remaining traces 

 of balsam may be removed by an old linen rag dipped in tur- 

 pentine or sulphuric ether. 



MOUNTING IN THE DRY WAY. 



For objects which require a high magnifying power, they 

 may be placed on a slide and covered with thin glass, whose 

 edges may be touched with cement. Objects which do not 

 require an object-glass of short focus, may be placed between 

 two slips of glass whose edges have been levelled so as to form 

 a groove, which may be filled up with cement or sealing-wax. 



If the object be too thick to allow the cover to approach the 



