106 VIEWS OF THE MICROSCOPIC WORLD. 



with great rapidity, and the swift advance of their spreading configurations gives 

 full employment to the eye of the observer. A group of the various combinations 

 afforded by the bichromate of potassa is delineated in drawing 157. A represents 

 the primitive crystals as they are seen at the edges of the film, but the two most 

 common forms are running vines and plume-like tufts, consisting of numerous 

 crystallized branches of the most delicate structure. The first is often seen origi- 

 nating in a single stem, which as it grows, soon breaks up into a thousand curved 

 shoots, that interlace and entwine with each other, composing a kind of irregu- 

 lar crystallized network extending over the surface before occupied by the liquid. 

 Two sprigs of this enwreathed crystallization are delineated at B and C. The lat- 

 eral spurs are short, forked, and disposed along the stem without any particular 

 regard to symmetry ; and are often loaded with comparatively heavy crystals, 

 the whole presenting an appearance not unlike a spray of withered herbage 

 fringed with crystals of hoar-frost. A specimen of the second kind is shown at 

 D, where numerous slender ramifications are seen radiating from a single stem, 

 each filament being studded at the side with minute crystals. These glitter- 

 ing plumes are scattered in profusion over the whole field of view, amid the 

 sparkling network of crystallized vines, and the union of these rich and radiant 

 configurations dazzles the eye with visions of rare and surpassing beauty. A 

 singular form is presented at E ; the solution has crystallized in circles around a 

 particle of sediment ; the circles are gemmed with crystals at the sides, and 

 terminate in branching sprigs as graceful as the leaflets of a flower. These 

 delicate sprays are very small, the breadth of the crystal at a in F measuring 

 only one-sixteen hundred and sixtieth part of an inch. 



SULPHATE OF SODA, OR GLAUBER SALTS. This salt crystallizes slowly by the 

 application of a gentle heat, and exhibits a great diversity of combinations, 

 which are, for the most part, massive, and stand boldly out upon the surface of 

 the glass. One variety commences in a spicular cluster, similar to that delineated 

 at A in drawing 158, the branches of which spread out in long needle-shaped 

 crystals on every side, which, intersecting with others of similar nature, frequently 

 form an irregular crystallized lattice work. Sometimes long and massive crystals 

 radiate from a common centre like the spokes of a wheel. Another variety of 

 crystal, of a delicate white color, broad, pointed, and shaped like a feather, is 

 often seen advancing in the field of view, and sending forth its glittering filaments 

 on either hand. In other parts of the crystallized film, a number of these crys- 

 tals are beheld ranked side by side, like the teeth of a comb, and the surface ot 

 each is itself studded with still smaller crystals. Rich, starry crystals are also 

 found, like those displayed in group B, and the other forms which are here de- 

 lineated are scattered in profusion amongst the rest. Very beautiful figures are 

 frequently observed near the edges of the drop where the salt is most abundant. 

 Two of these are exhibited at C and D, the first of which is a heavy transparent 

 configuration of considerable thickness with serrated sides, formed of single dia- 

 mond-shaped crystals. The second is a very singular crystalline structure, and 



