GLASS RODS AND PIPETTES 



147 



instead of flat mushroom form, thus permitting the removal of 

 stoppers or vials more quickly and easily, and in having all the 

 vials glass stoppered instead of half of them with rubber stoppers. 

 The common acids, such as hydrochloric, nitric, sulphuric and 

 acetic, in daily use may be kept in small bottles provided with 

 pipettes, Fig. 79. In similar bottles distilled water, dilute 

 ammonia and dilute glycerine may be placed. A tiny shallow tray 

 will be found convenient for holding the set of liquid reagents. 

 Small bottles holding liquid reagents must frequently be emptied 



V 



FlG. 79. Reagent Bottle with 

 Barnes Pipette. (X|.) 



FIG. 80. 



Ebonite Tubes for Ammonium 

 Fluoride. 



and filled with fresh material, owing to the extraction of soluble 

 constituents from the glass walls of the containers. 



Ammonium fluoride and other fluorine compounds are placed 

 in small stoppered tubes made of hard rubber, Fig. 80, or in 

 cerosine-lined vials. In the latter case frequent renewing of the 

 reagent is essential. 



Glass Rods and Pipettes. The tiny amounts of reagents 

 required for microchemical tests are most conveniently removed 

 from bottles and vials by means of drawn-out glass rods or 

 by platinum wires mounted in a glass handle. The type of glass 

 rod found to be most useful is shown in Fig. 81; if one or two 



