7 6 



Laboratory Arts 



Where possible, in addition to these cements, a strip of 

 transparent linen binding (such as is sold for repairing music) 

 may be applied to the outside of the joints. 



Lantern cells, Figs. 64 and 65, spectrometer prism cells, 

 Figs. 66 and 67, covers for specimens, and many other useful 



appliances are easily built up 

 in this way, top and bottom 

 being cemented on after the 

 sides are made, by the same 

 cement that is used for the 

 edges, and the article com- 

 pleted before the binding 

 wire or string is removed. 



The angle between the 

 various surfaces may be varied as desired by the use of suit- 

 ably inclined blocks, e.g. a 55 prism may be built up in this 

 way, and subsequently based and covered as explained above. 



FIG. 65. View of above. 



FIG. 66. Polariscope, or spectrometer cells made from glass tubing 

 and sheet glass. 



3. Drilling Glass. A prism to be used for benzene or 

 carbon disulphide may, with advantage, be covered with a plate 

 in which a hole has been drilled, and some little trouble is 

 frequently experienced in drilling glass for such purposes. 

 Two methods may be made use of 



