246 The Mickoscope, 



titute of ammoniacal odor, cool and add the water. The entire 

 removal of the ammonia gas requires the constant stirring of the 

 liquid with a glass rod, and rather lengthy heating. 



The finished product is a permanent, deep ruby-red liquid, per- 

 fectly transparent, destitute of ammoniacal odor and mixes, without 

 turbidity, with all aqueous solutions. About ten drops of this solu- 

 tion, added to a drachm of distilled-water, will stain a specimen 

 nicely in about five minutes.'' 



PiCEic ACID. — A saturated, aqueous solution can be made by 

 adding twenty grains of the acid to three ounces of distilled-water, 

 and left, with occasional shaking, for twenty-fovu* hours. It should 

 then be filtered to remove the excess of crystals. This solution stains 

 very rapidly, and gives a firm, yellow color. Though a rather dif- 

 fuse stain, it has a preference for epithelial structures. It can be 

 used for hardening small pieces of soft tissue, staining them at the 

 same time. Specimens thus prepared take picro-carmine most 

 beautifully. 



The following is Friedl?ender's formula, a most excellent one: 



Hsematoxylin, 2.00. 



Alcohol, 100.00. 



Distilled - water, 100.00. 



Glycerine, 100.00. 



Alum, 2.10. 



Dissolve tiie hematoxylin in the alcohol and slowly add the gly- 

 cerine. Dissolve the alum in distilled-water and add cautiously to 

 the first mixture. This makes a permanent fluid, but it is better to 

 filter before using, as some precipitation may have occui*red. It does 

 not attain its best powers under a week or ten days after making. 

 This solution makes a most elegant nuclear stain. If it be desired 

 to differentiate the connective tissues as well, it may be followed by a 

 dip in the picric- acid solution. This makes a very pretty double- 

 stain. Ha3matoxylin-stained sections must be preserved in Canada 

 balsam, as the color is eventually destroyed by glycerine. 



Note. — The writer has had several unsatisfactory preparations 

 of htematoxylin made. The cause was supposed to be that the 

 extract was used instead of the h?ematoxylin. Since using the latter 

 no troiible has been experienced. 



Silver nitrate. — The formula and method of using this solution 

 will be found in the fourth lesson, page 172. 



