ETHERS, ETC. 2Q 



entiated so that globoids and crystalloids are dis- 

 tinguishable. 



Since the evaporation of glycerine is almost 

 imperceptible, it is one of the best preservatives 

 for permanent preparations ; but as it absorbs the 

 moisture of the air when concentrated, the cover- 

 glass should be sealed with some air-tight cement. 



ETHERS, ETC. 



ETHER, BENZOL, CHLOROFORM, BISULPHIDE OF 

 CARBON, ETHEREAL-OILS. 1 



As reagents for determining to what extent a 

 substance is a fat, a volatile oil, a resin, etc., sub- 

 stances have been employed which, from a chemi- 

 cal standpoint, are often quite different. They 

 allow us to recognize these substances because of 

 their solvent powers. For this purpose ether, 

 chloroform, alcohol, benzol, oil of turpentine, and 

 carbon bisulphide are used. 



l Weiss: Allgemeine Bot, 1878, p. 178. DeBary : Vergl. Anatomic, 

 p. 86. H. de Vries : Keimung des rothen Klees. Landwirthschaftliche 

 Jahrb., 1877, Bd. VI., p. 468. Nageli : Das Mikroskop, 1877, p. 476. 

 Dippel : Das Mikroskop, I., p. 374. Wiesner : Technische Mikroskopie, 

 p. 8 1. For the use of carbon bisulphide as a reagent for sulphur, see this 

 substance in Part II. 



