50 THE ART OF PROJECTING. 



CAPILLARITY. 



The chemical tank (Fig. 20), containing a little colored 

 water, may be projected in any convenient way. If a 

 small glass tube be placed vertically in the tank, the 

 solution will rise in it. A series of five or six tubes, 

 with bores of different size, may be placed in this tank 

 at the same time, and the whole projected. The water 

 will be seen to rise higher as the tube is smaller. A 

 plate of glass three or four inches square may be put 

 down into the tank, bringing one of its edges against 

 one side of the tank. The water will rise two or three 

 inches where the glasses touch, and slope away with a 

 beautiful curve, which will vary as the whole side of the 

 glass is nearer, or more distant from the other one. 



CRYSTALLIZATION. 



It is always fascinating to watch the growth of crys- 

 talline forms, especially when the process can be leis- 

 urely studied over a surface fifteen or twenty feet 

 square. In all cases, a high magnifying power will be 

 needed. Three hundred or four hundred diameters is 

 better than any less. 



If this is to be shown by a lantern, it will be neces- 

 sary to have a powerful light, and the attachment known 



as the microscope at- 

 tachment (Fig. 31), 

 which fits upon the 

 lantern (Fig. 26) when 

 adjusted for horizontal 

 projection. The lens 

 must run forward nine 

 or ten inches, and the 

 *''' 31 ' jet drawn back until 



the maximum of light goes through the objective, which 



