ZIEHL-NKELSKN METHOD 213 



hydrochloric acid in alcohol, in which it is moved to and 

 fro for one minute, and is then rinsed in water. Some 

 drops of a dilute aqueous solution of methyl blue are now 

 poured upon it, when, after again washing and drying, it is 

 passed three times through the flame and mounted in 

 Canada balsam. 



In the Ziehl-Neelsen process, the cover-glass with the 

 sputum is seized in a forceps, covered with an alcoholic 

 carbolic fuchsine solution, warmed over a feeble spirit flame 

 until bubbles appear, washed in water, and flowed with a 5 

 per cent, solution of sulphuric acid. It is then rinsed in 70 

 per cent, alcohol, dried, and double-stained with aqueous 

 solution of methyl blue or malachite green. 



According to Friedliinder's method, some sputum is 

 smeared on two slides, which are drawn three times through 

 the flame. The sputum is then covered with two or three 

 drops of carbolic fuchsine, passed afresh through the flame, 

 moistened with water and a few drops of nitric acid alcohol 

 (3 per cent, of nitric acid in 90 per cent, alcohol), rinsed in 

 water and watery solution of methyl blue, and examined 

 without a cover-glass under the oil-immersion objective. 



Kiihne recommends shaking up the sputum thoroughly 

 in a glass with a concentrated solution of borax, so as to 

 render it fluid. The cover-glasses prepared with this are 

 stained in carbolic fuchsine for five minutes, decolorised in 

 30 per cent, nitric a.cid, rinsed in water, dried, and examined 

 in a drop of aniline oil coloured light yellow with picric acid, 

 which is best done. by adding two or three drops of a con- 

 centrated solution of picric acid in aniline oil to a watch- 

 glass full of pure aniline oil. To obtain permanent pre- 

 parations the double-staining should be done by transference 

 for a few minutes to an aqueous solution of picric acid after 

 decolorising with nitric, after which the specimen is dried 

 and put up in balsam. An addition of 4 per cent, citric 



