The Commercial Value of Monazite

1895 Scientific American  
rElll l l", 1'-(lIt THE !!'(;IEl'iTIFIC AiUERICAK. sists of an upright wooden cylinder open at the top and closed at the bottom, where a valve connects it with bamboo pipes leading to the furnace. The cylinder is fitted with a plunger, which is moved downward by hand and upward by a spring pole to which it is fastened. The iron ore is roasted about twelve hours in a wood fire and then broken into small pieces and mixed with ten times it s volume of charcoal for smelting. When a lump of iron is
more » ... a lump of iron is finally produced it is taken out of the furnace with wooden tongs and hammered with wooden mallets. It is then cut into small pieces and hammered again until the slag is driven out, and a very good grade of soft steel remains. The waste is said to be one-third. THE COMMERCIAL VALUE OF MONAZITE. It begins to look as though the great value of monaz ite mining lands had been very much overestiwated. There is. of course, a demand for rare earth oxides for the manufacture of incandescent gas lamps, etc., but the supply of monazite is, unfortunately for the specu lator, practically unlimited, and its price has dropped correspondingly. Monazite (from pOrdr;ElY, to be solitary) was so called in allusion to its supposed rarity. For a long time sub"eq uent to its discovery in Norway it was be· lieved to exist nowhere else. It was afterward found. however. in Silesia. Bohemia. Belgium. England. Brazil and the United States. The deposits in this country are near Norwich, Conn., and in North Carolina. Monazite is in substance a phosphate of cerium. lan thanum and didymium. con taining �ilicon and tho rium in variable proportions, probably as impurities. Tite oxides of the rare earth metals, cerium, thorium, yttriulIl. erbium, lanthanum and zirconium possess the peculiar property of becoming incandescent at a mod erate heat. The light emitted is the greatest in the ca�e of thorium, and this oxide of this metal is ob_ tained principally from monazite. It is used exten sively in the Wel8bach lamp, where a network mantle of the oxide is suspended over a Bunsen burner and produces an intense white light. When monazite was discovered in North Carolina, great excitement prevailed for a time. Fabulous sto_ ries of the value of the resinous-looking substan!)e were circulated and sand from the river bottoms was carefully washed over in cradles like those used by the gold prospectors of California. Some of the pioneers made a good deal of money at first, but, as the wash ing process is exceedingly laborious and slow when conducted by hand. and many tons of sand must be washed to extract one of monazite, nobody got rich. Nevertheless the people all believed firmly that illl mense fortunes could be made with proper apparatus for mining. and chemil.'ts and engineers in the North ern cities were overwhelwed with letters and circulars JUNE 22, 1895.] in which monazite lands were offered as great bargains at absurdly high prices. Meanwhile the representatives of the consumers had quietly placed contracts at the lowest possible figure and the price of the mineral began to drop. As last winter was a severe one and the ice in the rivers inter fered with the washing', good, clean monazite sand sold for fifteen cents a pound. Now it can be had for fiye or six cents, and there is not a great demand at that. It is doubtful whether the entire output of North Carolina since the discovery of the mineral has brought $125,000 . SOME FACTS ABOUT GLASS. The most scientific glass workers of to-day are no more proficient in their art than were the craftsmen of ancient Thebes 4,000 years ago. These remarkable artisans, many of whom were priests high in authority, were well acquainted with glass staining, and dis played the highest artistic skill in their tints and de· signs. The colors were perfectly incorporated with the structure of the vitrified substance and were equal ly clear on both sides. The priests of Ptah, at Mem phis, had a factory for the manufacture of ordinary glass, and also devoted their attention to imitating precious stones, succeeding so well that specimens now found require an expert to distinguish them from the real gems. They were also acquainted with the use of the diamond for cutting glass. A specimen of beauti fully stained glass, now in the British Museum, has th e cognizance of Thothmes III engraved upon it. Spun glass was first brought into practical use about fifty years ago by Jules de Brunfaut, a French chemist, although the art of spinning glass was practiced long before that time. He made a thorough study of the subject in Vienna. He first succeeded in softening the hard, shiny effect of the glass fabric, giving it a silky effect that was much more pleasiug. Next he en deavored to reduce its brittleness by making a spun glass, whose threads were much finer than those of silk, and whose texture was much like that of wool. This glass could readily be woven and all kinds of arti cles were made of it. Among other things it was found especially suitable for surgical use, owing to its anti septic properties and its cleanliness. The fact that glass is unattacked by most acids made the fabric use ful for laboratory filters, and ne!lrly all well equipped establish ments of the kind now use them. The cloth is, besides, non·combustible and a poor conductor of heat. As the individual fibers are perfectly non-ab sorbent, grease spots and stains can be readily re moved. For this same rea:;on the cloth cannot be dyed, but it can be spun of colored glass and the color is absolutely fast and unchanging. Up to the beginning of the sixteenth century the glass used in stained glass work was what is known as .. pot metal," that is, it was colored in mass through its entire substance. Painting was only used to bring out the shading and fine line work, and the paint was al ways brown, which was afterward" fired " into glass. During the sixteenth century a rich yellow stain, ob tained by the use of silver salts, came into use. It was also used upon blue glass to produce green effects. Shortly afterward the irregular depths of tint in the glass were first utilized to give modeling. The ruby glass used at this time was made by placing a thin layer of ruby" pot metal" upon the surface of a sheet of white glass and welding the two together by heat, a" the ruby alone became opaq ue as soon as any thickness was reache d. It soon occurred to some one to cut or grind a way the ru by surface to produce white figures on the red ground. By staining the exposed portions, they were also able to get rich yellow and red contrasts. This led to extending the practice to other colored" pot metals," until a great variety of beauti ful effects were prod uced. When glass contains little or no lime it shows a marked tendency to become opaque upon cooling, probably owing to minute crystallization throughout its structure. The so-called alabaster glass is made by reheating glass of this kind and allowing it to cool slowly. Opalescent glass is that which possesses the same tendency in less degree. A good " mix," as it is called by glass workers, for alabaster glass is 100 parts of quartz !'land, 45 parts of potash, 3 parts of calcined borax and 5 parts of silicate of magnesia.
doi:10.1038/scientificamerican06221895-386e fatcat:ejvvpd2wgbdv7lonktgrq75f3a