70 LIGHTING AND FOCUSING [ CH. II 



CARE OF THE MICROSCOPE 



122. The microscope should be handled carefully and kept 

 perfectly clean. The oculars and objectives should never be allowed 

 to fall. 



When not in use keep it in a place as free as possible from dust. 



All parts of the microscope should be kept free from liquids, 

 especially from acids, alkalies, alcohol, xylene, turpentine and 

 chloroform. 



123. Care of the Mechanical Parts. To clean the mechan- 

 ical parts put a small quantity of some fine oil (olive oil or liquid 

 vaselin and gasoline or xylene, equal parts), on a piece of chamois 

 leather or on the lens paper, and rub the parts well, then with a 

 clean dry piece of the chamois or paper wipe off most of the oil. If 

 the mechanical parts are kept clean in this way a lubricator is rarely 

 needed. When opposed brass surfaces "cut," i. <?., when from the 

 introduction of some gritty material, minute grooves are worn in the 

 opposing surfaces, giving a harsh movement, the opposing parts 

 should be separated, carefully cleaned as described above and any 

 ridges or prominences scraped down with a knife. Where the ten- 

 dency to " cut " is marked, a very slight application of equal parts 

 of beeswax and tallow, well melted together, serves a good purpose. 



In cleaning lacquered parts, xylene alone answers well, but it 

 should be quickly wiped off with a clean piece of the lens paper. 

 Do not use alcohol as it dissolves the lacquer. 



124. Care of the Optical Parts. These must be kept 

 scrupulously clean in order that the best results may be obtained. 



Glass surfaces should never be touched with the fingers, for 

 that will soil them. 



The glass of which the lenses are made is quite soft, consequent- 

 ly it is necessary that only soft, clean cloth or paper be used in 

 in wiping them. 



Whenever an objective is left in position on a microscope, or 

 when several are attached by means of a revolving nose-piece, an 

 ocular should be left in the upper end of the tube to prevent dust 

 from falling down upon the back lens of the objective. 



125. Lens Paper. The so-called Japanese filter paper, 

 which from its use with the microscope, I have designated lens paper, 



