REAGENT VIALS 
145 
thus be computed by measuring the plane angles of the dififerent 
faces in turnd 
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 ^ 
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. 77) ,3 the stoppers of which are numbered or 
lettered and the contents recorded upon a small 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 
^ Kley, Rec. trav. chim. Pays-Bas., 19 (1900), 13. 
^ 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. 
