GQ PYROMETALLURGT. [ill. 



* W7nte, Malleable Alloy. — Parkes gives the two following 



proportions (Rep. of Pat. Inv. July 1845) : 



33ft) zinc, 64ft) tin, l|ft) iron, 2^ft) copper. 

 50 " 48 " 1 " 3 " 



The iron and copper are first fused together, the tin then 

 added, and lastly the zinc. The flux consists of 1 pt. lime, 

 1 pt. fluor spar, and 3 pts. salammoniac. It is cast in sand 

 or moulds. Another alloy consists of : 



66 zinc, 32^ tin, 3| antimony. 



79f " 19i 



25. 



-"4 



It is fused with black flux, and, if used for sheathing ships, 

 I to 1 per cent, arsenic should be added. The alloy may be 

 rolled cold into thin sheets. 



Alloys for Dentists. — The following proportions are re- 

 commended : 



1. 2. 3. 4. 5. 



Gold 1 ... 1 ... 1 ... - ... 6 



Silver - ... 1 ... 1 ... 1 ... - 



Platinum 2 ... 4 ... 2 ... 2 ...10 



Palladiuin — ... — ... — ... — ... 8 



The gold and silver are first fused, and the platinum and 

 palladium then added. They are fused in small crucibles and 

 require a blast. The solder for these alloys is either pure 

 gold or an alloy of gold and silver. (Rep. of Pat. Inv. 1845, 

 p. 72.) 



Amalgam for Filling Teeth. — Pettenkofer (Ann. der Chem. 

 und Pharm. 1849) has described an amalgam used by dentists. 

 It is very hard, adhesive, and of a grayish color ; and, owing to 

 the very slight difference of density in the soft and hard state, 

 it occupies the same space when cool as in the plastic state. 

 This latter condition is given by heating the amalgam to 

 nearly the boiling point of mercury, and then triturating it, 

 for some time, in a mortar. After cooling, it is soft and 

 readily worked either with the fingers or tools. In a few 

 hours, it becomes intensely hard. The following is the best 

 process for the preparation of this amalgam. Weigh out a 

 quantity of pure .mercury, dissolve it in a q. s. of hot sul- 



