THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 

 OCTOBER 1863. 



XXXIV. On Ccssium. By Professor Bunsen*. 

 [With a Plate.] 



IN the first detailed communication which Kirchhoff and I 

 made respecting caesium and some of its compounds, pub- 

 lished in vol. xxii. pp. 329 & 498 of this Magazine, we distinctly- 

 stated that the determination of the atomic weight of the new 

 metal there described could only be considered as preliminary. 

 The quantity of material, extracted from nearly one-hundred 

 thousand pounds of the mineral water of Durkheim, with which 

 the whole investigation had to be made, amounted only to from 2 

 to 3 grammes, and therefore did not permit an exact and defini- 

 tive estimation of the atomic weight. Since the publication of 

 this memoir, I hoped to obtain a more abundant supply of mate- 

 rial from the water of the " Murquelle " in Baden-Baden, which 

 exhibits the reactions of csesium and rubidium more plainly than 

 the Durkheim mineral water. I found, however, after evapo- 

 ting 30,000 lbs. of this water, using for this purpose nearly 

 5 tons of coal, that the mother-liquor yielded only 1*5 grm. of 

 pure chloride of csesium. According to an investigation made 

 by Professor Bixio, 1000 parts of this mother-liquor possesses 

 the following composition : — 



Sulphate of calcium . . . 1*861 

 Sulphate of strontium . . . 0*492 

 Biborate of calcium . . . 0*035 

 Chloride of sodium . . . 218-964 

 Chloride of potassium . . . 53*416 

 Bromide of potassium . . . 0*303 

 Chloride of rubidium . . . 0*336 

 Chloride of caesium . . . 0*229 

 Chloride of lithium . . . 17*825 

 Chloride of calcium . . . 10*495 

 Chloride of magnesium . . 0*254 



304*210 

 * Communicated by Professor Roscoe, F.R.S. 

 Phil Mag, S. 4. Vol. 26. No. 175, OcU 1863. R 



