MECHANICS AND USEFUL ARTS. 



75 



ably the best proportion to use for bells made at one melting, is a much 

 " higher" metal, as they call it, than the modern bell-founders, either Eng- 

 lish or French, generally use. As there is no great difference in the price of 

 the two metals, the reason why they prefer the lower quantity of tin is, that 

 it makes the bells softer, and therefore easier to cut for turning, which is ob- 

 viously a very insufficient reason. I advise every body who makes a con- 

 tract for bells, to stipulate that they shall be rejected if they are found on 

 analysis to contain less than twenty-two, or, at any rate, twenty-one per 

 cent, of tin, or more than two per cent, of anything but copper and tin. 



Analysis of several JBell-Metals. 



COATING IEOX WITH GLASS. 



Mr. T. G. Salt, Birmingham, G. B., has patented a method of enamelling 

 cast iron, or coating it with glass, by the use of pounded enamel or glass 

 applied to the surface by means of gum water, or other adhesive matter, and 

 afterwards fused. The surface of the cast iron is first cleaned by turning, 

 filing, scouring, or otherwise ; and then is applied a thin coating of gum water 

 or other adhesive solution, by sponging or brushing upon the said surface. 

 While the surface is still damp, the powder described as mixture No. 1, is 

 dusted on the surface. The article is then heated until the powder fuses, 

 when a uniform gray vitreous surface is produced. If a white surface is re- 

 quired, a second coating of the adhesive solution must be given, and the 

 powder described as mixture No. 2, is dusted over it, and the article is again 

 heated until the composition fuses. 



MIXTURE No. 1. Oxide of lead, 20 Ibs. ; boracic acid, 20 Ibs. ; cullet,* 

 60 Ibs. ; soda, 3 Ibs. 6 ozs. ; nitre, 1 Ib. 2 ozs. ; oxide of manganese, 5 ozs. 

 = 104 Ibs. 13 ozs. 



MIXTURE No. 2. Sand, 25 Ibs. ; cullet, 30 Ibs. ; oxide of lead, 50 Ibs. ; 

 soda, 5 1 Ibs.; nitre, 4 Ibs. 10 ozs. ; white arsenic, 3^ Ibs.; oxide of anti- 

 mony, 8| ozs. = -- 119 Ibs. 10:| ozs. 



These materials are pounded and intimately mixed, and then fused. The 

 result is an enamel, which has to be again pounded, and then used as de- 

 scribed. 



* Cullet, an English term for broken glass. 



