1896 THE MICROSCOPE. 83 



formed. In fig. 1 n are some of the simplest forms of 

 sugar crystals. 



Some kinds of ink, if spread on a slide and allowed to 

 dry slowly, produce crystals. Stafford's ink which had 

 stood for some time produced the crystals shown in fig. 

 2, but a slide made of some recently purchased gave 

 only a few crystals and those principally in toothed 

 lines. This polarizes well. 



Chlorate of potash makes a pretty slide. Dissolve 

 some of the potash in a little water and spread a drop 

 on a slide. Let it dry in a cool place and it will give 

 tabular crystals (fig. 1 k). If a permanent mount is 

 desired, dissolve some small pieces of gelatine in about 

 as much distilled water, make a saturated solution of 

 chlorate of potash, add a few drops to the gelatine and 

 stir gently with a glass tube, being careful not to form 

 bubbles, then spread a drop on a cover-glass. If in a 

 cool place it will dry in about half an hour. If the 

 crystallization has been successful a slide may give such 

 forms as are seen in fig. 3. The crystals shown in fig. 4 

 were found near that shown in fig. 3 b but were so small 

 as to appear simply as points of light with the same 

 magnification as used in drawing fig. 3. Fig. 1 / repre- 

 sents one branch of a tree-like pattern which was found 

 in another slide. To form these dentritic or tree-like 

 crystals, heat a drop of the solution on a slide over a 

 spirit lamp and as soon as the crystals begin to form at 

 any point, tilt the slide so that the water will run off. 

 Then continue the crystallization by gentle warmth. By 

 comparing these different forms of this crystal it will 

 be seen how easily they might be mistaken for crystals 

 of different salts. Chlorate of potash gives fine colors 

 with the polariscope. 



Fig. 5 represents a group of sugar crystals taken 

 from a slide which contained fifteen similar groups ; 



