REAGENT VIALS 145 



thus be computed by measuring the plane angles of the different 

 faces in turn. 1 



Lens Holders. Frequently low magnifications are required 

 in preparing or separating material for microscopic study, but 

 placing the objects upon the stage of the compound microscope 

 is inconvenient or impossible. Recourse may then be had to 

 magnifiers held in some sort of easily adjustable stand. The 

 author has found a stand of the general style shown in Fig. 76 2 

 to be the most useful. The lens holder itself, consisting of a 

 spring clip C, renders the stand applicable to a wide variety of 

 uses other than merely supporting lenses. The hinged arms and 



FIG. 76. Lens Holder. 



thumb-screw admit of adaptation to any position and to all 

 angles and elevations. The rack and pinion serves as a fine 

 adjustment or to facilitate the examination of the surfaces of 

 irregular objects. 



Reagent Containers. Dry reagents for microchemical analy- 

 sis are conveniently kept in tiny glass-stoppered vials in a block 

 of wood (Fig. yy), 3 the stoppers of which are numbered or 

 lettered and the contents recorded upon a smalt chart which 

 may be placed under the glass plate on the work table. A trans- 

 portable set of reagents is shown in Fig. 78, modeled after the 



1 Kley, Rec. trav. chim. Pays-Bas., 19 (1900), 13. 



2 Made by the Bausch & Lomb Optical Co., Rochester, N. Y. 



3 These reagent vials and block may be obtained from the Will Corporation 

 Rochester, N. Y. 



