216 ANNUAL OF SCIENTIFIC DISCOVERY. 



two bright indigo-colored lines, and by its compounds tinting the 

 colorless flame of a Bunsen burner of a violet color. Hitherto indium 

 has only been obtained in very minute quantity from the Fryberg 

 blende, consequently its properties and compounds have not been very 

 carefully examined. It appears closely to resemble zinc, with which 

 it has hitherto always been found in combination. It is, however, a 

 softer metal, marking paper like lead ; it is readily soluble in hydro- 

 chloric acid, and, heated in the open air, it oxydizes freely, yielding 

 a white oxyd easily reducible before the dcoxydizing flame of the 

 blow-pipe. The hydrated oxyd is precipitated from its salts by pot- 

 ash and ammonia, but is insoluble in excess of either of these re- 

 agents ; hence it is easily distinguished from both zinc and alumina. 

 The oxyd may be separated from oxyd of iron, with which it is as- 

 sociated in the zinc blende by precipitating the latter with bicarbonate 

 of soda. The precipitated sulphide is insoluble in alkalies. 



Caesium and Rubidium have recently been found to be exten- 

 sively distributed, and to exist in many articles of human consumption, 

 such as beet-root, sugar, tea, and coffee. TiiaHium has been found in 

 many minerals in which its presence was hitherto unsuspected, and to 

 occur also in very appreciable quantity in molasses, the yeast of wine, 

 chicory, and even in tobacco. 



A new and comparatively abundant source of these three rare metals, 

 caesium, rubidium, and thallium, has been discovered; the water of a 

 spring near Frankfort, Germany, leaves on evaporation a saline residue 

 which contains the three metals in appreciable quantity. Rubidium is 

 a very light metal ; with a white color like silver, with a yellowish shade. 

 In contact with air it covers itself immediately with a bluish gray coat- 

 ing of suboxyd, is inflamed (even when in large lumps) after a few 

 seconds, much quicker than potassium. At a temperature of 14 Fahr. 

 it is still as soft as wax ; it becomes liquid at 101-3 Fahr., and in red 

 heat it is transformed into a greenish-blue vapor. The specific gravity 

 of rubidium is about 1'52. It is much more electro-positive than po- 

 tassium ; and when thrown upon water, burns and shows a ilame like 

 that metal. 



Caesium and Tellurium, The metal cccsium has hitherto been ob- 

 tained only in very small quantities. To get only seven grains of its 

 chloride Bunsen was obliged to evaporate forty tons of water ; and only 

 0*3 per cent, of it are contained in the Lepidolite of Hebron in the 

 United States. But it has recently been found that the mineral Pol- 

 lux, which is very abundant in the island of Elba, contains 34 per 

 cent of this metal, which had been previously mistaken for potas- 

 sium. Tellurium also, hitherto one of the rarest of substances, is 



found in considerable quantity associated with bismuth, about 15,000 

 feet above the level of the sea, in one of the loftiest peaks of the An- 

 des. The reduction of chloride of aluminum by means of zinc 



was patented in 1854, but the principle was not successfully carried 

 out until recently. The vapor of zinc is found to reduce cobalt, nickel, 

 and manganese with great facility. 



Use and distribution of Lithium. Lithia, the oxyd of the metal 

 lithium, since the discovery of its wide distribution by the process of 

 spectral anal} sis, has been introduced to a considerable extent into 

 medicine, in the form of a carbonate, as an anti-acid and anti-lithic 



