APPARATUS, MATERIAL, AND REAGENTS. 43 



surplus stain from cover glasses, etc., and the latter 

 is conveniently placed for disinfection of vessels and 

 hands after cleansing with water. They should be 

 placed on the top of a cupboard, or on a high 

 shelf. 



Desiccator The Desiccator (Fig. 25) consists 

 of a porcelain pan containing concentrated sulphuric 

 acid, and covered over with a bell-glass receiver. 



FIG. 25. DESICCATOR. 



The sheet of plate-glass upon which the pan rests 

 is ground upon its upper surface, and the rim of 

 the glass bell is also ground and well greased. In 

 the centre of the pan is a column supporting a 

 circular frame, which is covered with wire gauze. 

 Slices of potatoes, upon which micro-organisms 

 have been cultivated, are rapidly dried by the 

 action of the sulphuric acid in confined air. A 

 cultivation of Bacterium prodigiosum^ for example, 



