358 REAGENTS AND THEIR PREPARATION [CH. X 



oughly. If it is allowed to remain in a warm place (i.e., in a place 

 where the gelatin remains melted) the air-bubbles will rise and dis- 

 appear. 



In case the glycerin jelly remains fluid or semi-fluid at the ordinary 

 temperature (i8-2o C.), the gelatin has either been transformed into 

 meta-gelatin by too high a temperature or it contains too much water. 

 The amount of water may be lessened by heating at a moderate tem- 

 perature over a water bath in an open vessel. This is an excellent 

 mounting medium. Air-bubbles should be avoided in mounting as 

 they do not disappear. 



571. Glycerin jelly for anatomic preparations. Specimens 

 prepared by the Kaiserling method or other satisfactory way may 

 be permanently preserved in glycerin jelly prepared as follows: Best 

 clear gelatin, 200 grams. Kaiserling's No. 4 solution, 3000 cc. (Po- 

 tassium acetate, 100 grams; glycerin, 200 cc.; water, 1000 cc). Put 

 the gelatin in the potassium-acetate-glycerin-water mixture in an 

 agate pail and heat over a gas or other stove. Stir. When the tem- 

 perature is about 55 centigrade add the whites of three eggs well 

 beaten, and stir them in vigorously. Make markedly acid by acetic 

 acid. Continue the heating until the mixture just boils, and then 

 filter through filter paper into fruit jars. It is best to put over the 

 filter paper two thicknesses of gauze. A piece of thymol in the top of 

 each jar will prevent the growth of fungi, or one can add 5 % chloral 

 hydrate. Specimens are mounted in this jelly directly from the No. 

 4 Kaiserlings, or alcoholic specimens can be soaked in water an hour 

 or more and then kept in some of the melted jelly until well soaked; 

 then mount permanently in the glycerin jelly. At the time of mount- 

 ing the gelatin is liquefied over a water bath, and for every 20 cc. of 

 the gelatin used one drop of strong formalin is added. This is to 

 prevent the liquification of the gelatin after the specimen is mounted. 

 Let the gelatin cool gradually after the specimen is in place, then 

 add some melted gelatin to make the vessel over full and slide a glass 

 cover on it. This excludes all air. The cover may then be sealed 

 with the clear gelatin or glue used for gluing wood, or the cement 

 used in mending crockery. Finally, one can seal with rubber cement 

 if desired. (See W. H. Watters, N.Y. Med. Record, Dec. 22, 1906.) 



