82 PREPARATION AND MOUNTING 



it is much better when diluted with two parts of camphor-water, 

 prepared as above. * 



GLYCERINE AND GUM. This is also believed to be a very good 

 liquid for vegetable tissues, and is thus prepared : 



Pure gum-arabic . . 1 oz. 



Glycerine . . . . 1 " 



Water (distilled) . . 1 " 



Arsenious acid . . 1-|- grains. 



Dissolve the arsenious acid in the cold water, then the gum, add 

 the glycerine, and mix without bubbles. 



DEANE'S COMPOUND. This is usually deemed about the best 

 medium for preserving Algse, mosses, &c., and is thus prepared : 

 Soak 1 oz. of best gelatine in 4 oz. of water until the- gelatine 

 becomes soft, when 5 oz. of honey heated to boiling-point are 

 added ; boil the mixture, and when it has cooled, but not enough 

 to become stiff, add ^ oz. rectified spirit with which 5 or 6 drops 

 of creasote have been well mixed, and filter the whole through 

 fine flannel. This compound when cold forms a stiff jelly, the use 

 of which will be described elsewhere. 



GLYCERINE JELLY. This mixture closely resembles the above, 

 but as the composition differs a little it may be mentioned here. 

 It is strongly recommended by Mr. Lawrance in the Microscopic 

 Journal, where he states " that the beautiful green of some mosses 

 mounted two years ago, is still as fresh as the day they were 

 gathered ;" and that this is the only medium he knows which will 

 preserve the natural colour of vegetable substances. He takes a 

 quantity of Nelson's gelatine, soaks it for two or three hours'in 

 cold water, pours off the superfluous water, and heats the soaked 

 gelatine until melted. To each fluid ounce of the gelatine, whilst 

 it is fluid but cool, he adds a fluid drachm of the white of an egg. 



* Dr. Carpenter says: " Glycerine has a solvent power for carbonate of 

 lime, and should not be employed when the object contains any calcareous 

 structure. In ignorance of this fact, the author ( Dr. C.) employed glycerine to 

 preserve a number of remarkably tine specimens of the pentacrinoid larva of 

 the Comatula, whose colours he was anxious to retain; and was extremely 

 vexed to find, when about to mount them, that their calcareous skeletons had 

 so entirely disappeared, that the specimens were completely ruined." 



