MOUNTING AND PREPARATION OF OBJECTS. 73 



before they arrive at a condition suitable for micro- 

 scopic investigation. A very slight sketch of the 

 plan adopted is here given to enable those who do 

 not possess a lapidary's workshop to investigate 

 these substances under low powers. 



A rough slice is cut from the substance with a 

 small saw or by chipping ; one side is fastened with 

 balsam about an inch from the extremity of a board ; 

 twelve inches long, two inches wide, and half an 

 inch thick. When the balsam has hardened, the 

 upper surface of the specimen is flattened with a file, 

 next rubbed down on a perfectly flat Arkansas stone; 

 and finally polished with putty powder spread on a 

 leather pad ; a simple microscope is useful for watch- 

 ing the progress of the latter operation. When 

 finished this side is fastened on the wood ; the 

 specimen filed down as thin as possible, and the 

 foregoing process repeated. 



If the specimen is very brittle it is best attached 

 to a glass slip, and saturated with balsam, before 

 commencing operations on the second surface. 



The finished section may be now removed from 

 the wooden support by soaking in turpentine, after 

 which it is transferred to clove oil, and then to ab- 

 solute alcohol. On removal from this the alcohol is 

 allowed to evaporate spontaneously, and the section 

 mounted dry or in balsam. 



For the preparation of injected specimens and 

 other processes, we refer the reader to the authorities 

 already mentioned, reminding them of the fact,, that 

 violet and blue solutions are unsatisfactory for stain- 



