MICROSPECTROSCOPE 
137 
means of shellac or balsam. The short pieces of tube fit snugly 
into the hole in the cork and are pressed tightly against the object 
slide. The tubes are thus easily removable and readily cleaned. 
Fig. 68 . Calibration Curve of a Seibert Microspectroscope. 
Or we may employ a cell of the type devised by Andrews.^ This 
consists of a glass tube about 2 cm. in diameter and of any con¬ 
venient length (see Fig. 69) cemented upon an object slide with 
DeKhotinsky cement. The observation tube about 5 mm. in 
^ Dr. W. W. Andrews, Regina, Canada. Unpublished manuscript. 
