Ch. X] REAGENTS AND THEIR PREPARATION 351 



the color would fade or diffuse if the medium were not slightly acid. 

 For hematoxylin and many other stains the acid is detrimental. For 

 example, the slight amount of acid in the balsam causes the delicate 

 stain in the finest fibers of Weigert preparations to fade. To neutralize 

 the balsam add some pure sodium carbonate, set the balsam in a 

 warm place, and shake it occasionally. After a month or so the soda 

 will settle and the clear supernatant balsam will be found very slightly 

 alkaline. Use this whenever an acid medium would fade the stain 

 in the specimen. 



§ 547. Acid balsam. — As stated above all balsam is naturally 

 somewhat acid, but for various stains it is desirable to increase the 

 acidity. For example, specimens stained with picro-fuchsin, or 

 injected with carmine or Berlin blue are more satisfactory and last 

 longer with full brilliancy if the balsam is made more acid than it 

 naturally is. For this use 10 to 20 drops of glacial acetic or formic 

 acid to 100 cc. of balsam. 



§548. Borax carmine for in toto staining. — Borax 4 grams; 

 carmine 3 grams; water 100 cc. Shake frequently for several days 

 and then filter and add 100 cc. of 67 % alcohol. After 3 to 4 days it 

 may be necessary to filter again. Good for in toto staining after almost 

 any fixer. Put the object to be stained from alcohol into a vial with 

 plenty of stain. After a day or two change the stain. Stain 4 to 

 5 days. Remove to 67% alcohol, adding 4 drops of HC1 to each 

 100 cc. of alcohol. After one day remove to 82 % alcohol. Change 

 the alcohol till no more color comes away, then proceed to section. 

 Remember that objects stained in toto may be mounted directly in 

 balsam from deparaffining xylene. 



§ 549. Carmine for mucus (mucicarmin). — One can buy the dry 

 powder or preferably prepare the stain. To prepare it take 1 gram of 

 Carmine No. 40 and \ gram of pure dry ammonium chlorid. If the 

 latter is slightly moist, dry it in an evaporating dish in a sand bath. 

 Mix the ammonium chlorid and the carmine and add 2 cc. of water. 

 Mix well and heat over a sand bath, constantly mixing with a glass 

 rod. Continue the heating until the carmine colored mass becomes 

 very dark red. It will take 3 to 10 minutes for this. The heat 

 should not be too great. 



