138 ANNUAL OF SCIENTIFIC DISCOVERY. 







ble to any known clement. The indefatigable experimenters, acting 

 on the testimony thus obtained, evaporated down no less a quantity 

 than twenty tons of the mineral water in question, and obtained from 

 the residuum two hundred and forty grains of the platinum salt of a 

 new metal which they hare named CAESIUM, from the Latin word 

 ccesius. signifying grayish-blue, that being the tint of the two spectral 



i.^* / 



hues which it shows. Further investigations showed the presence of 

 cassium in other mineral waters, and led to the detection of another 

 element, which, from the circumstance of its yielding two very dark 

 red spectral lines, has been termed RUBIDIUM, from the Latin rubi- 

 dus, dark red. Both of these metals resemble potassium so closely 

 that they cannot be distinguished from it by the usual re-agents, or 

 before the blowpipe. Their presence in minute quantities can only 

 be recognized by aid of the new method of spectral analysis. 



Properties of the new Metals. Caesium appears to be the constant 

 companion of rubidium, and has thus far been found most abundant 

 in the saline waters of Diirkheimer, in Germany. The atomic weight 

 of CEesium is 123.4 (H = l) : Symbol, Cs. It is the most electro-posi- 

 tive of all known elements. 



Caustic caesia resembles caustic potash; carbonate of cassia is soluble 

 in alcohol, in which reaction it differs from the carbonate of rubidia ; 

 sulphate of cassia forms alum with the sulphate of alumina. Chloride 

 of caesium is deliquescent like the chloride of lithium. 



Messrs. Bunsen and Kirchhoff have found traces of rubidium in 

 almost all mineral waters ; but it exists in greatest quantity in the 

 mineral known as lepidolite ; some of which, from Moravia, was found 

 to contain about ^^^ths of its weight of the oxide of rubidium. The 

 atomic weight of it is 85.36 (H = l) : Symbol, Rb. 



Caustic rubidia resembles caustic potash; carbonate of rubidia is 

 insoluble in alcohol ; it can be readily converted into bicarbonate. 

 Xitrate of fubidia varies from nitrate of potassa in crystalline form. 

 Sulphate of rubidia is isomorphous with sulphate of potassa, and forms 

 cubic alum with the sulphate of alumina. Chloride of rubidium crys- 

 tallizes in cubes. 



Another new element, Thalium. Mr. William Crookes. an English 

 chemist, also announces the discovery, by means of the photo-chemical 

 process of analysis, of another new element, belonging to the sulphur 

 group, to which he gives the name Thalium Gr. 0a)J.o;, green, from 

 the circumstance of its yielding an intensely green spectral ray. Thus 

 far the new element has been obtained in the form of a dense brown 

 powder, from specimens of native sulphur. Its physical and chemical 

 properties have not, however, as yet been described. 



It is scarcely possible to overrate the probable importance to chem- 

 ical science of this new and beautiful method of analysis. In fact, 

 the discoveries of Bunsen and Kirchhoff seem to herald the birth of a 

 new kind of terrestrial and stellar chemistry, inasmuch as it extends 

 almost to infinity the limits within which the chemical characteristics 

 of matter have hitherto been confined. " In spectral analyses," ob- 

 serve the discoverers of the process, " the colored bands are unaffected 

 by any alteration of physical conditions, or by the presence of other 

 bodies. The positions, therefore, which the lines occupy in the spec- 

 trum, indicate the existence of a chemical property as unalterable as 



