296 



ELEMENTARY CHEMICAL MICROSCOPY 



is removed from time to time by means of capillary pipettes. 

 This little apparatus also makes a convenient generator for hydro- 

 gen and arsine in testing for arsenic. 



When temperatures of vaporization are needed the bulb con- 

 taining the liquid can be introduced into the hot stage described 



Fig. 156. Tube for Microchcmical Distillations. (Full Size.) 



on page 224, the receiving bulb being kept outside of the stage 

 and cooled with wet filter paper, the tube connecting the two 

 little bulbs having been bent at the proper angle. 



Ignition, Fusion, etc. — Operations involving heating to red- 

 ness are best performed in small platinum cups or spoons, Fig. 

 157, over the low flame of a Bunsen burner or that of a miniature 

 blast lamp. 



Fig. 157. Platinum Cups for Fusions. (Full Size.) 



Fig. 158. Casserole for Microchemical Analysis. (Full Size.) 



In the absence of alkalies tiny cups with handles made of fused 

 silica are convenient, Fig. 158; or tiny porcelain casseroles can 

 be used. All the apparatus illustrated are standard commercial 

 forms and may be obtained from dealers in chemical apparatus. 

 Small crucibles are occasionally useful, especially those corre- 

 sponding to No. 9 and 10 Meissan porcelain. Since, however, 



