CHiiMICAL SCIENCE. 205 



NEW FUSIBLE METAL. 



Dr. B. "Wood, of Nashville, Term., has recently secured a patent for a new 

 fusible alloy, composed of cadmium, tin, lead, and bismuth, which fuses 

 at a temperature between 1-30 and 160 Fahrenheit. The constituents of 

 this fusible metal may be varied according to the other desired qualities of 

 tiie alloy, viz.: cadmium, one to two parts; bismuth, seven to eight parts; 

 tin, two parts; lead, four parts. It is recommended as being especially 

 adapted for all light castings requiring a more fusible material than 

 Rose's or Newton's "fusible metal," it having the advantage of fusing at 

 more than 40 J Fahrenheit lower temperature than these alloys; and, owing 

 to this property, may replace many castings heretofore made only with 

 amalgams. 



In a communication to the U. S. Mining Journal, Dr. Wood says: 



The advantage of possessing the joint qualities of great fusibility, malle- 

 ability, strength, etc., in a metal designed for use as above, is too evident to 

 dwell upon. 



One of the most useful of this class is the alloy commonly called "fine 

 solder," consisting of one part of lead and two parts tin. It is perfectly 

 malleable, highly tenacious, and melts, according to Professor Graham, at 

 the temperature of 360 Fahrenheit, being the most fusible of any of the 

 mixtures of lead and tin. But its melting point is too high for a solder for 

 the more fusible tin-metals, such as the ordinary pewter and Britannia-ware, 

 etc. Another objection is its softness. 



The alloys consisting of lead, tin, and Jbismuth, commonly called " bismuth 

 solders," are harder and more fusible, but they are proportionably brittle. 

 A common formula for very easily melted solder is, sixteen parts tin, eight 

 lead, four bismuth. A more fusible mixture and the most fusible alloy 

 hitherto known is that discovered by Sir Isaac Newton, consisting of three 

 parts tin, five lead, eight bismuth. This melts, according to Professor 

 Graham, at 20.2 Fahrenheit. No practical improvement has ever been 

 made upon this by any combination of the constituents, although certain 

 combinations possess, according to some experimenters, a lower melting 

 point by one or two degrees, a difference too slight for appreciation by 

 ordinary tests. Practically, the melting point is somewhat higher, requiring 

 a temperature of about 210 for perfect liquefaction. In view of its remark- 

 able fusibility this alloy has received the distinguishing name of "fusible 

 metal." It is too brittle for ordinary use as a solder, but is much employed 

 for casting, and in making dies for light work, and for taking impressions 

 from medallions and other objects. Melting below the temperature of 

 boiling water, it may be used upon the fresh plaster cast, or other moist 

 surface. But it has the disadvantage that when used at a heat barely suffi- 

 cient for fusion, it is not fluid enough to take the sharp outlines, and congeals 

 before it can flow into the interstices; while a small additional heat raises its 

 temperature above that at which water boils, whence steam is produced, 

 which spoils the work. 



The melting point of these alloys may, as is well known, be lowered to 

 any extent by the addition of mercury; but this metal, even In small pro- 

 portions, renders them so frail and brittle as to be worthless for the ordinary 

 uses. It also causes them to tarnish, and is partly eliminated from the com- 

 pound, being retained rather as a foreign admixture than as a chemical 

 constituent, whence it occurs that these amalgams injure other metals with 



18 



