THE 



PHILOSOPHICAL MAGAZINE, 



y U lY E 1 800 . 



I. Rtfearches feJpcB'ing the Compojtthn of Enamel, By 

 C. Clouet, Ajjociate of the French National Injiitute*-, 



WHITE ENAMEL. 



W HITE enamel, either for earthen-ware, or the piif- 

 pofe of being applied on metals, is compored in the following 

 manner: You firft calcine a mixture of lead and tjn, which, 

 may be varied in the following proportions ; -^liz. for lOO 

 parts of lead, 15, 20, 30, and even 40 of tin. A mixture of 

 lead and tin calcines very eafily in contaft with the air. As 

 foon as this mixture is brought to a red heat, nearly a cherry 

 colour, it burns like charcoal, and is calcined very fpeedily. 

 The compofition which calcines bed, is that which in 100 

 pounds of lead contains from 20 to 25 of tin. The tin here 

 meant is pure tin. In proportion as the calcination is ef- 

 fected, you muft take out the calcined part, and continue to 

 oxydate the reft until the whole has become pulverulent. As 

 fome fniall particles always efcape calcination, you muft ex- 

 pofe to the fire a fecond time the oxyd obtained in order to 

 calcine it completely; which may be eafily known by its 

 ceafing to iparkle ; that is to lay, when you no longer fee 

 any par^s burn like coal, and when the whole appears of an 

 uniform colour. When the proportion of tin exceeds 25 

 or 30, a ftrontrer fire is neceifary to produce the calcination. 

 In a word;, by varying the degrees of heat you will be able 

 * ¥iomi\\f: A':"'es de Cbimie. 



