USEFUL MICROSCOPE ACCESSORIES 



123 



When deliquescent or corrosive materials are to be handled 

 the forceps should be provided with solid platinum tips, Fig. 70. 

 No microchemical outfit can be considered as complete without 

 platinum tipped forceps. Just as in the case above cited the 

 roughening at the tips should be carefully removed and at least 



FIG. 70. Forceps with Platinum Tips. (Full size.) 



one of the tips also filed flat and smooth on the outside, thus al- 

 lowing the tip to be used as a tiny spatula. Tips should be 

 sufficiently stiff and rigid to permit holding fragments firmly to 

 obviate all danger of dropping material or bending the tips. 

 Foil-like tips are for this reason an abomination since the slightest 

 excess of pressure causes them to bend and loosen. 



Object Slides and Other Supports. Object slides or slips 

 employed in microchemical analysis should be from i to 1.5 

 millimeters thick and made from glass of such composition as to 

 be as resistant as possible to the action of solvents. The color- 

 less glass object slides in common use in America, so excellent 

 for ordinary microscopic work, are easily attacked by all the 

 usual solvents and reagents employed in qualitative analysis. 

 Great care, therefore, is necessary when very minute amounts 

 of material are to be tested, to avoid being led into serious error 

 arising from the extraction of constituents from the glass slides. 



Object slides of greenish glass, the usual material supplied 

 some years ago, and sometimes still found on sale, are much 

 better, being harder and more resistant to the action of chemicals. 



Standard slides, 3 inches by i inch, are too long and should 

 be cut in half, or half-size slides purchased, since microchemi- 

 cal reactions are generally performed at the corners of the 

 slides, seldom if ever at the center. A full-sized slide cannot be 

 satisfactorily rotated on the stage of the polarizing microscope 

 with the material situated at one corner, since the slide extends 

 too far beyond the rim of the stage; nor can material be heated 

 at the center of the slide without incurring the danger of breaking. 



Object slides of ordinary non-resistant glass rapidly become 



