BISMUTH, I:Azimuth, a metallic element, first accurately described by Pat in 1739. It was known before that time, but had been previously confounded with antimony and zinc, which it resembles to some extent. Bis muth occurs in nature in the metallic form, always in small quantities, and generally asso ciated with copper, lead, cobalt, nickel, arsenic, silver, tin or rarely iron. It is found in various form — massive, granular, reticulated and arborescent. Several ores of it also are known, from which the metal may be easily obtained by roasting and smelting. The prin cipal supply in Europe- comes from Saxony, but considerable quantities are obtained from Austria, Norway, England, Spain and New 'Vales. ales. The largest known deposits are those of Bolivia where it is found as the hydrated oxide. In Mexico it is found as carbonate. Native bismuth is found in Cali fornia but in very small quantities. Small amounts have been reported from Utah. The total consumption of the metal probably does not greatly exceed 50 tons per annum and the demand for it is so variable that the price has ranged all the way from 50 cents to $5 a pound. Bismuth is a grayish-white metal with a peculiar reddish tone, as compared with other white metals, and is highly crystalline, and so brittle that it can be readily pulverized. It melts at 510° F., and boils in the vicinity of 2300° F. Its specific gravity is about 9.82 at 54° F.,.that of the melted metal, just above the point of fusion, being 10.06. Its specific heat is about 0.030 at ordinary temperatures, and 0.036 just above the melting point. Its coefficient of ex pansion is about 0.000736 per degree Fahren heit, its conductivity for heat is about one fiftieth of that of silver and its electrical re sistance at 32° F. is 1.15 times that of mercury at the same temperature. Bismuth is readily recognized by the spectroscope, as it shows a large number of characteristic lines. Its chemical symbol is Bi, and its atomic weight is 208.5 in the scale where 16. It has tensile strength of 6,400 pounds per square inch. Ac
cording to some authorities, the specific gravity of metallic bismuth is diminished by pressure; but Spring has shown that this is not the case. He subjected a sample whose specific gravity was 9,804 to a pressure of 20,000 atmospheres, and found that the specific gravity rose to 9.856, while a second compression increased it still further, to 9.863. Bismuth expands upon solidifying, but Tribe has shown that this expansion does not take place until immediately after the con elation of the metal. Bismuth is the most diamagnetic substance known, a sphere of it being sensibly repelled by a magnet. It has marked thermo-electric properties also, on account of which it is much used in con nection with antimony in laboratories in the construction of delicate thermopiles. In the arts, metallic bismuth is used chiefly in the preparation of alloys. By adding a small amount of it to lead, that metal may be hard ened and toughened. An alloy consisting of three parts of lead and two of bismuth has 10 times the hardness and 20 times the tenacity of pure lead. The alloys of bismuth with both tin and lead are extremely fusible, and take fine impressions of casts and molds, owing to their property of expanding at the moment of solidifying. An alloy of one part of bismuth, two parts of tin, and. one part of lead, is used by pewter workers as a soft solder, and by soap-makers for molds. An alloy containing five parts of bismuth, two of tin and three of lead melts at 199° F., and is somewhat used for stereotyping, and for the manufacture of metallic writing pencils. Thorpe gives the following proportions for the better known fusible metals, into which bismuth enters: Newton's: Bismuth, 50; lead, 3125; tin, 18.75. Melts at 202° F.
Rose's: Bismuth, 50; lead, 28.10; tin, 24.10, Melts at 203° F.
D'Arcet's: Bismuth, 50; lead, 25; tin, 25. Melts at 201° F. (If 250 parts of mercury are also added, the resulting alloy, or amalgam, melts at F.) Wood's: Bismuth, 50; lead 25; tin, 12.50; cadmium, 12.50. Melts at 149° F.