174 ANNUAL OF SCIENTIFIC DISCOVERY. 



liquid or solid surfaces. The impact of the gaseous molecule, upon 

 *a surface possessing a different temperature, appears to be the con- 

 dition for the transference of heat, or the heat movement, from one to 

 the other. The more rapid the molecular movement of the gas, the 

 more frequent the contact, with consequent communication of heat. 

 Hence, probably, the great cooling power of hydrogen gas as compared 

 with air or oxygen. The gases named have the same specific heat for 

 equal volumes, but a hot object placed in hydrogen is really touched 

 3.8 times more frequently than it would be if placed in air, and 4 

 times more frequently than it would be if placed in an atmosphere of 

 oxygen gas. Dalton had already ascribed this peculiarity of hydrogen 

 to the high " mobility " of that gas. The same molecular property of 

 hydrogen recommends the application of that gas in the air-engine, 

 where the object is to alternately heat and cool a confined volume of 

 gas with rapidity. 



THE NEW METALS. 



Indium. In the summer of 1863, thallium having been detected in 

 minute quantities in many of the products of the smelting works at 

 Freiberg, Saxony, F. Reich and Th. Richter, examined some of the 

 ores, at the laboratories of the works, hoping to ascertain its source. 

 These ores consisted of pyrites, mispickel, blende, and galena ; with 

 earthy matter, silica, manganese, copper, and minute quantities of tin 

 and cadmium. The ores were roasted to expel the greater part of the 

 sulphur and arsenic ; then mixed with hydrochloric acid, evaporated to 

 dryness and distilled. The impure chloride of zinc thus obtained was 

 examined before the spectroscope for thallium. No thallium line was 

 found ; but, instead, an indigo blue line, entirely new, and different 

 from that produced by any known substance. The experimenters suc- 

 ceeded in isolating the conjectural substance, necessarily in very minute 

 quantity, partly in the form of chloride, partly as hydrated oxide, and 

 partly in the metallic state. On submitting these, moistened with 

 chlorhydric acid, to the spectroscope, the blue line was seen so brilliant, 

 sharp, and persistent, that they did not hesitate to conclude that it be- 

 longed to a hitherto unrecognized metal, to which they accordingly 

 gave the name Indium. Its chemical properties have not as yet been 

 fully determined. Its chloride is not precipitated from an acid solution 

 by sulphuretted hydrogen, but is precipitated from the same solution 

 by ammonia, as a hydrated oxide. The oxide, fused on charcoal with 

 soda, yields a lead-gray globule of metal, very soft and ductile ; while 

 the metal heated alone on charcoal gives a yellow coating, which, 

 upon being moistened with nitrate of cobalt, gives no characteristic 

 reaction. 



Rubidium and Ccesium. - - M. Seybcl, an Austrian chemist, has re- 

 cently prepared five ounces of the chlorides of rubidium and coesium, 

 in a state of perfect purity, from 800 Ibs. of the mica of Finnwald, in 

 Bohemia. This mica contains nearly 3 per cent, of the oxides of these 

 tAvo metals, which is a more considerable proportion than is known at 

 present in any other substance. M. Scybel is engaged in making ar- 

 rangements for the production of these interesting substances in larger 

 quantities, so as to render them accessible to all interested in chemical 

 pursuits. Prof Bunsen, of Heidelberg, also announces, that he has met 



