468 transactions of the american institute. 



The Metal Palladium. 



Dr. Parmelee exhibited a coil of palladium wire weighing about four 

 ounces, Troy, and valued at about $600. He states the sample was manu- 

 factured by Messieurs Desmontes, Morin & Chapuis, of Paris, and that the 

 specimen is more interesting from the fact of its being chemically pure, 

 while others are generally alloyed with from 40 to 60 per cent, of silver. 

 Its general characters are like those of platinum; but, while it is infusible 

 in an ordinary wind furnace, it melts at a lower temperature than that 

 metal. Its specific gravity is 1 1.5; atomic weight, 52.24. It occurs chiefly 

 in the ore of platinum, in the proportion of about one per cent.; it is ex- 

 tracted by dissolving this ore in aquaregia, and precipitating the palladium 

 from the solution by chloride of ammonium. After filtration the palladium 

 is separated by cyanide of mercury as cyanide of palladium. This is usually 

 converted into a sulphide by heating it with sulphur; and afterward the 

 sulphur is expelled by repeated heatings. There are other processes of a 

 more complicated character and probably less valuable. Palladium has 

 been applied in a few cases to the construction of graduated scales of 

 astronomical instruments. Porcelain manufacturers employ it in some 

 instances to produce a fine silver gilt on ornamental wares. It is also used 

 in bronzing brass for ornamental purposes. Photographers also employ 

 the chloride to some extent for toning their pictures. The scarcity of the 

 metal has limited the application of it to few uses. This wire is the one- 

 thirty-eighth of an inch in diameter, and is worth about $40 per foot. 



Prof. Seely remarked that a few years ago, at a meeting of the Photo- 

 graphical Society, Dr. Draper suggested that palladium might be used to 

 advantage for toning photographs. When photographs are made the darks 

 are silver, and the color of this metal is not pleasing to the eye; photogra- 

 phers therefore dip their pictures into a solution of gold, which gives them 

 a beautiful purple color. Dr. Draper's suggestions attracted a good deal 

 of attention, and palladium was probably inquired for at every place in 

 the city where there was any reason for supposing that it might be found. 

 There was none to be had, and the speaker applied to Dr. Draper, who said 

 that a few years before there was plenty in the market at $10 per ounce. 

 The, supply had been exhausted by makers of gas fixtures and othei's, who 

 used the metal for giving a beautiful bronze finish to their work. 



Prof. Everett stated that a few years since he obtained about four ounces 

 of palladium from some platinum ore that he was analyzing, and he made 

 it into a solution of chloride of palladium, to be used for bronzing. After 

 selling three bottles it was discovered that the supply in the market was 

 running short, und when we sold the first lot from the fourth bottle, my 

 partner filled up the bottle with water. The solution seemed to work just 

 as well till it became very weak, so that we got as much for the fourth 

 bottle as we did for the other three. 



Mr. Maddock stated that the bronzing- of porcelain is now effected with 

 a preparation of iron. 



Thread. 



Dr. Rowell illustrated by a piece of tape that if a thread or other string 

 is wound on a card with the right hand, holding the card in the left, a twist 



