Lipowitz's: Bismuth, 50; lead, 26.90; tin, 12.78; cadmium, 10.40. Melts at 149° F.
Guthrie's alloy: Bismuth, 50; lead, 20.55; tin, 21.10; cadmium, 14.03. Melting point not definitely stated, but said to be °very low.° See FUSIBLE METALS..
The action of heat upon some of the fore going alloys is remarkable. Thus, Lipowitz's alloy, which solidifies at 149°, contracts very rapidly at first, as it cools from this point. As the cooling goes on, the contraction becomes slower and slower, until the temperature falls to F. From this point the alloy expands as it cools, until the temperature falls to about 77° F., after which it again contracts, so that at 32° a bar of the alloy has the same length as at 115° F. Alloys of bismuth have been used for making fusible plugs for steam boil ers, but it is found that they are altered in some unknown way by prolonged exposure to heat, so that they cannot be relied upon, after any great length of time, to melt at the proper temperature. Some of the alloys of bismuth are also used in tempering steel.
In its compounds, bismuth has an odd valency — usually three, but sometimes five. Metallic bismuth does not oxidize readily in dry air at ordinary temperatures, but it burns with a blue flame when strongly heated in presence of air, passing into the trioxide, If the trioxide is dissolved in a solu tion of caustic potash, and nitric acid is sub sequently added, bismuth peroxide (or pent oxide, Bit0,,, is precipitated. The trioxide is pale yellow, and the pentoxide is brownish-red.' The trioxide exists in nature as °bismuth ochre? It is used for staining glass and porce lain. Both unite with acids to form salts. Bismuth trichloride, BiC13, is formed when the metal is heated in chlorine gas; it is a white, crystalline, deliquescent substance, which is decomposed by water with the formation of hydrochloric acid and bismuth oxychloride BiOCI. Bismuth trisulphide, is thrown down as a black, insoluble precipitate, when a stream of sulphuretted hydrogen gas is passed through an acid solution of a salt of bismuth. The trisulphide also occurs native as °bismuth glance,° or Bismuthinite (q.v.). Bismuth dis
solves readily in nitric acid, with the formation of the nitrate, Bi(NO3)2+ 5H20. A pecu liarity of the soluble bismuth salts, as a class, is that their solutions are rendered milky by the addition of water in considerable excess, owing to the formation insoluble basic com pounds. The nitrate, for example, becomes transformed by this process into a series of so-called sub-nitrates.
. In medicine, bismuth is used in the form of some one of this metal's insoluble salts, the soluble salts of bismuth being actively poison ous. The poisoning closely resembles that caused by lead (q.v). The insoluble salts used most frequently are bismuth subnitrate, sub carbonate, salicylate and subgallate. These are for the most part employed as gastric sedatives, as gastrointestinal anti- fermentatives, and locally as bland astringent dressings.
Practically the entire commercial supply of bismuth in the United States market is obtained as a by-product in smelting lead, copper, gold and silver ores. In the lead-silver mines at Leadville, Colo., occur occasional pockets of ore that are relatively rich in bismuth. These ores are smelted separately to secure a lead rich in bismuth, which is afterward treated by the electrolytic process to recover the bis muth. A very large quantity of bismuth is vaporized and escapes from the chimneys of the great smelters. An examination at the Anaconda smelter proved that not less than 800 pounds of metal was lost daily in this way. The demand, however, is limited, and the production is kept by the manufacturers at a point where the price which can be obtained will be large enough to make the recovery profitable. The latest figures on the produc tion of bismuth in the United States given by the Geological Survey are those for 1914—a total of. 220,000 pounds, valued at $426,000. Since then the government has ordered the figures concealed, as they might reveal facts relating to private business. The imports have fallen off in value from $330,000 in 1913 to $180,000 in 1915.