92 CARE OF THE MICROSCOPE CCh. in 



Caxe of the Microscope 



§ 155. The microscope should be handled carefuUy and kept per- 

 fectly clean. The oculars and objectives should never be allowed to 

 faU. 



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



AU parts of the microscope should be kept free from liquids, espe- 

 cially from acids, alkaHes, alcohol, xylene, turpentine, and chloroform. 



§ 156. Care of the mechanical parts. — To clean the sliding me- 

 chanical parts put a small quantity of some fine oil (ohve oil or hquid 

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

 leather, or lens paper, and rub the parts well; then with a clean dry 

 piece of the cloth 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.e., when from the introduc- 

 tion 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 tendency to 

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

 and tallow, well melted together, serves a good purpose. The thick 

 fibrous grease such as is used in the grease cups of automobiles is also 

 good. 



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. 



§ 157. Care of the optical parts. — These must be kept scrupu- 

 lously clean in order that the best results may be obtained: 



Glass surfaces should never be touched with the fingers, for that 

 will soil 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 fall- 

 ing down upon the back lens of the objective (§ 15 7a). 



§ 157a. As pointed out by Wright, p. 93, one of the surest ways to detect 

 anything wrong with the objective is to examine the eye-point with a magnifier. 



