INTRODUCTION. 17 



and 10 grams of strong alcohol are added, a liquid is obtained 

 which is known as Prey's fflycerin-carmin. 



/ c_/ , 



84. Scales carmin is nearly the same. Ten grains of carmin 

 are placed in a test-tube, and half a drachm of strong ammonia 

 added ; the mixture is shaken, and gently heated over a spirit- 

 lamp. The solution is to be boiled for a few seconds and then 

 allowed to cool. In an hour two ounces of glycerin and two 

 ounces of water are to be added, together with half an ounce of 

 alcohol; the liquid is then filtered. 1 



85. Thiersclis borax-carmin. 2 '2 grams of borax are dis- 

 solved in '2* c. c. of distilled water, and .5 gram of carmin 

 added. The solution is next mixed with GO c. c. of absolute 

 alcohol, and filtered. 



86. Thiersch's oxalic-acid carmin* 1 gram of carmin is 

 dissolved in 1 c. c. of ammonia and 3 c.c. of water. Another 

 solution is prepared by dissolving 8 grams of crystallized oxalic 

 acid in 175 c.c. of water. The two solutions are then mixed, 

 16 c.c. of absolute alcohol added, and the whole filtered. This 

 liquid is violet when ammonia is in excess ; orange, if too much 

 oxalic acid is present. 



87. Grenadier's alum-car min.* Carmin is dissolved in a 

 solution of potash-alum or ammonia-alum until the required 

 color is obtained. This has been modified by Tangl as follows : 

 To a saturated solution of alum, enough carmin is added to give 

 a deep color (1 grin, in 100 c.c. of solution), the whole boiled 

 for ten minutes, and filtered upon cooling. 



88. Wbo<7/r</,-<rs can in n. kt Pulverized carmin 7| grains, 

 water of ammonia 20 drops, absolute alcohol half an ounce, 

 glycerin 1 ounce, distilled water 1 ounce. Put the pulverized 

 carmin in a test-tube and add the ammonia. Boil slowly for a 



V 



few seconds, and set aside uncorked for a day, to get rid of the 

 excess of ammonia. Add the mixed water and glycerin, and 

 next the alcohol, and filter." 



89. Carmin with picric acid. This agent, known as Ran- 

 vier's picrocarmin, is made by cautiously adding to a concentrated 

 solution of picric acid enough ammonia-carmin solution (81) 

 to saturate it, and then evaporating to one-fifth the volume. 



1 Beale : How to "Work with the Microscope, p. 125. 



2 Behrens: Hilfsbuch, p. 258. 



3 Behrens : Hilfsbuch, p. 257. In Dippel(DasMikroskop), p. 285, the pro- 

 portions are somewhat different. 



4 Archiv. fur Mikrosk. Anat., 1879, p. 465. Tangl, in Pringsh. Jahrb., 

 Bd. xii., 1880, p. 170. 



2 



