194 ANNUAL OF SCIENTIFIC DISCOVERY. 



on a solution of protochloride of mercury (HgCl), and on cooling 

 deposited a small quantity of minute crystals. 



" The chloride of this metal differs, therefore, from the protochlo- 

 ride of tin, in not reducing protochloride of mercury to calomel, and 

 in being but slightly soluble in the cold. 



" In 1852, Dr. F. H. Genth announced the existence of a new metal, 

 occurring among grains of platinum received from California. It 

 was malleable; it fused readily on charcoal before the blow-pipe, 

 becoming covered with a coating of black oxide; it dissolved in 

 borax to a colorless bead, which became opalescent on cooling; it 

 was dissolved by hot hydrochloric acid, and by nitric acid; and its 

 solution gave a brown precipitate with hydrosulphuric acid. It 

 seems quite probable, therefore, that the metal which I have observed 

 in the Rogue River platinum is identical with that observed by Dr. 

 Genth." 



DIFFUSION OF RUBIDIUM. 



M. Grandeau discovers this newly-recognized metal in coffee, tea, 

 tobacco, grapes and crude tartar. The tobacco employed came from 

 Kentucky and Havana. The leaves were acted upon by water, 

 which was evaporated, and the residue calcined and tested by the 

 method of spectrum analysis, which indicated potassium, a small 

 quantity of lithium, and a notable proportion of rubidium. Coffee is 

 still richer in rubidium than tobacco; but, as is the case with tea, 

 yields no trace of lithium. He found no rubidium in colza, cocoa, 

 and cane sugar, nor in certain kinds of fucus. 



NEW INFLAMMABLE GAS. 



At a recent meeting of the London Chemical Society, Dr. Hoff- 

 mann made a communication on the preparation of a spontaneously- 

 inflammable gaseous compound of silicon and hydrogen, which pos- 

 sesses many points of interest. He stated that it has long been 

 believed that silicon belongs to the same group of elements as car- 

 bon, but though the normal carburetted hydrogen, C 2 H 4 , has been 

 long known, indications only of the existence of the corresponding 

 silicon compound have been attained, and these quite recently. 

 Berzelius pointed out long ago the existence of a body which he 

 believed to contain hydride of silicon, it was a solid, however, not 

 a gas, --and will probably turn out to be the hydrated oxide of 

 silicon, since obtained by Wohler. It is to the latter chemist that 

 we owe the recognition of silicuretted hydrogen. While making 

 some experiments upon the decomposition of water, he employed a 

 plate of metallic aluminum as the negative terminal of his battery ; 

 and was surprised to find that instead of pure hydrogen being evolved, 

 as is usual with a platinum plate, a gas was evolved which inflamed 

 spontaneously. Upon investigation this gas was found to be com- 

 posed of hydrogen and silicum, the latter being an impurity in the 

 aluminum plate. Since then the following plan of making this gas in 

 abundance has been devised : Take eighty parts of fused chloride 

 of magnesium, seventy parts of silica-fluoride of potassium, forty 

 parts of sodium cut into small pieces, and twenty parts each of the 



