108 VIEWS OF THE MICROSCOPIC WORLD. 



seen interlacing in the most fantastic shapes. A remarkable characteristic of 

 these crystals is their softness of tint; they shine with a pearly whiteness, and 

 the light comes through them mild and subdued, like the gentle radiance of the 

 moon, imparting such a softness to these beautiful figures that they appear as 

 delicate as flower-wreaths, wrought on a satin ground. Another form is exhibited 

 in the figures at C and D ; it is a pearl-colored, lozenge-shaped crystal, and is 

 often seen small at first, but of perfect proportions. As the eye remains fixed 

 upon it, it is seen gradually to increase in size, retaining nevertheless, at the 

 same time, its original symmetry, a result which is effected by the sides expand- 

 ing uniformly from the centre of the crystal. Several modifications of this type 

 are presented in the drawing. A fourth variety consists of clusters of spicular 

 crystals, such as are depicted at F G, and another configuration is exhibited at 

 F, where the massive crystals cross each other, and interlock like the roots of 

 trees. At E the crystals form a serrated surface, resembling the plaits of a 

 frill. 



SULPHATE OF COPPER. The sulphate of copper affords a fine blue solution, 

 which forms quickly, upon the application of a moderate heat, into long spicular 

 crystals, uniting and blending with each other. The network of the crystals is 

 clearly discerned by the unaided eye, but the microscope is needed to display 

 their more intimate combinations, and the different configurations they assume. 

 In drawing 161 are delineated a number of crystals of sulphate of copper; 

 the long spicular figure C, at the top, is that which is first detected under the 

 microscope, pushing forward its sharp point into the crystallizing fluid. As it 

 advances it spreads out laterally, sending forth numerous crystals, mostly from 

 one side, which often unite so compactly together, as to constitute a triangular 

 plate. The form it then assumes is the same as that which is exhibited at D. 

 A more delicate and perfect configuration is displayed at a b ; the crystals of 

 which are exquisitely fine, especially those at the sides. Instead of being 

 blended together, as at D, they are distinct and separate from each other ; and in 

 every set branch from the main stem in exactly parallel directions. The dis- 

 tance between the two adjacent principal crystals a and 5, is only the one hun- 

 dred and ninetieth part of an inch. The cluster E consists of short prismatic 

 crystals, which are usually found in groups, near the edges of the liquid, wherever 

 the film is comparatively thick, and the matter held in solution quite abundant. 

 Profusely scattered throughout this locality, fine diamond-shaped crystals are 

 likewise often found. A rare configuration is delineated at F, consisting of a 

 minute and distinct portion of the liquid which has concreted without regularly 

 crystallizing throughout, a circumstance which often happens when too much 

 heat is applied to the glass slide. In the midst of this mass a beautiful spiral 

 system of exquisitely formed crystals is beheld, emanating from a central point, 

 and spreading its slender and plumy branches over the entire transparent 

 surface. 



