AQUARIA 



399 



For larger sizes it is safe to say that angle iron or 

 aluminium bronze, either cast in a single piece or riveted 

 at the corners, would be preferable. 



The corners of all sizes larger than 8x10x5, around 

 the bottom and up the vertical angles, should be laid as 

 represented in cross-section in Fig. 161, with a prism of 

 cement in the angle, covered by a narrow strip of glass. 

 This greatly strengthens the joint and protects the water 

 from the cement.^ 



A good aquarium cement, for either fresh or salt water, 

 is made by mixing dry ten parts each, by measure, of fine, 

 dry, white sand, plaster of Paris, and litharge, and one part 

 powdered resin. Mix as required, to a stiff putty with 

 boiled linseed oil. (This must be warranted free from 

 any trace of adulteration with fish oil, and it is commonly 

 necessary to buy raw oil of a practical painter, who should 

 know that it is pure, and boil it for 

 a few minutes, to drive off the water 

 in the raw oil.) The simplest and 

 best aquarium cement, the formula 

 of which has been given me recently 

 by the United States Fish Commis- 

 sion, is made as follows : Stir together 

 dry, by weight, eight parts putty (dry 

 whiting), one part red lead, and one Fig. 161. Section of 

 part litharge. Mix, as wanted for use, ^^^^^^ °^ Aquarium 

 with pure raw linseed oil, to consistency of stiff putty. 



r'CZ 



* 



wmk 



1 Although not necessary, I generally put one or two coats of copal, or 

 spar varnish, around the angles on the inside. No aquarium has leaked 

 when this has been done ; and if a leak occurs, it is necessary only to dry 

 very thoroughly and varnish on the inside around the angles. 



