CH. II] LIGHTING AND FOCUSING 71 



has been used in the author's laboratory since 1885 for cleaning the 

 lenses of oculars and objectives, and especially for removing the 

 fluid used with immersion objectives. Whenever a piece is used 

 once it is thrown away. It has proved more satisfactory than cloth 

 or chamois, because dust or sand is not present; and from its bib- 

 ulous character it is very efficient in removing liquid or semi-liquid 

 substances. 



§ 126. Removal of Dust. — Dust may be removed with a 

 camel's hair brush, or by wiping with the lens paper. 



Cloudiness may be removed from the glass surfaces by breathing 

 on them, then wiping quickly with a soft cloth or the lens paper. 



Cloudiness on the inner surfaces of the ocular lenses may be 

 removed by unscrewing them and wiping as directed above. A 

 high objective should never be taken apart by an inexperienced 

 person . 



If the cloudiness cannot be removed as directed above, moisten 

 one corner of the cloth or paper with 95 per cent alcohol, wipe the 

 glass first with this, then with the dry cloth or the paper. 



Water may be removed with soft cloth or the paper. 



Glycerin may be removed with cloth or paper saturated with dis- 

 tilled water; remove the water as above. 



Blood or other albuminous material may be removed while fresh 

 with a moist cloth or paper, the same as glycerin. If the material 

 has dried on the glass, it may be removed more readily by adding a 

 small quantity of ammonia to the water in which the cloth is moist- 

 ened, (water 100 cc. , ammonia 1 cc). 



Canada Balsam, damar, paraffin, or any oily substance may be 

 removed with a cloth or paper wet with chloroform, gasoline or 

 xylene. The application of these liquids and their removal with a 

 soft dry cloth or paper should be as rapid as possible, so that none 

 of the liquid will have time to soften the setting of the lenses. 



Shellac Cememt may be removed by the paper or a cloth moist- 

 ened in 95 per cent, alcohol. 



Brunswick Black, Gold Size, and all other substances soluble in 

 chloroform, etc. , may be removed as directed for balsam and damar. 



In general, use a solvent of the substance on the glass and wipe 

 it off quickly with a fresh piece of the lens paper. 



