148 ELEMENTARY CHEMICAL MICROSCOPY 



millimeters of the drawn-out end are slightly roughened with a 

 piece of fine carborundum or emery cloth, or ground on a wheel, 



FIG. 81. Drawn-out Glass Rod and Platinum Wire for handling Reagents. 



it will be found that both liquids and solids are more easily trans- 

 ferred and handled than if the glass be smooth. Slightly breath- 

 ing on the end of the rod, or touching it to one's fingers before 

 bringing it in contact with the reagent will cause tiny fragments 

 of dry powders to cling to the rod long enough to permit all usual 

 transfers. Similarly, roughening the end of the platinum wire 

 improves its carrying power. Rods and wires roughened, neces- 

 sarily require more care in cleaning after use than when polished. 



Tiny pipettes may be employed for transferring solutions or 

 liquid reagents, but are so difficult to keep thoroughly clean that 

 it is wiser to employ short lengths of tubing of capillary bore made 

 by drawing out odds and ends of glass tubing. Such substitutes 

 for pipettes draw up the solutions to which they are touched by 

 capillarity the liquid can easily be expelled by gently blowing 

 into one end of the tube, the other end being held against an 

 object slide. After transferring the liquid, the capillary tube is 

 thrown away. 



Spatulas. Larger amounts of dry reagents than can con- 

 veniently be handled by the glass rods or platinum wires may be 

 transferred by means of small platinum spatulas, Fig. 82, made 



FIG. 82. Platinum Spatula for Microchemical Analysis. (Full size.) 



from a piece of platinum wire about one millimeter in diameter 

 and 80 to 85 millimeters long, one end of which is hammered out 

 flat on a polished steel surface until it becomes a little over 3 

 millimeters wide and the flattened surface about 10 millimeters 

 long. The blade thus prepared is shaped and smoothed with a 

 fine file and polished. The end of the handle is given a gentle 



