194 THE ATOMIC WEIGHTS. 



Per cent. O. 

 1.8576 grm. SbCl3 needed .5967 grm. Y^,<Zrf).^ and 33.4 cc. sol. 7.0338 

 1. 91 18 " -3019 " KCIO3 " 16.2 " 7.0321 



4.1235 " .6S01 " " " 23.2 '• 7.0222 



Mean, 7.0294, i .0024 



The fourth set of experiments was gravimetric. The 

 solution of SbCla, mixed with tartaric acid, was first pre- 

 cipitated by hydrogen sulphide, in order to remove the 

 antimony. The excess of HjS was corrected by copper 

 sulphate, and then the chlorine was estimated as silver chlo- 

 ride in the ordinary manner. 100 parts of AgCl correspond 

 to the amounts of SbCl^ given in the third column. 



1.8662 grm. SbCIg gave 3.483 grm. AgCI. 53-58o 



1.6832 " 3.141 " 53.588 



2.7437 " 5-i"5 " 53-677 



2.6798 " 5.0025 " 53.569 



5.047 " 9.41 1 " 53-629 



3.8975 " 7-2585 " 53-696 



Mean, 53.623, rt .015 



The volumetric series with SbClg gave Kessler values for 

 Sb ranging from 121.16 to 121.47. The gravimetric series, 

 on the other hand, yielded results from Sb == 124.12 to 124.67. 

 This discrepancy Kessler rightly attributes to the presence 

 of oxygen in the chloride ; and, ingeniously correcting for 

 this error, he deduces from both sets combined, the value of 

 Sb = 122.37. 



The several mean results for antimony agree so fairly 

 with each other, and with the estimates obtained by Dexter 

 and Dumas, that we cannot wonder that Kessler felt satisfied 

 of their general correctness, and of the inaccuracy of the 

 figures published by Schneider. Still, the old series of data 

 obtained by the titration of tartar emetic with anhydrochro- 

 mate contained no evident errors, and was not accounted 

 for. This series,* if we reduce all of Kessler's figures to a 

 single common standard, give a ratio between KX'r2 07 

 and CJI.KSbO^.IH^O. 100 parts of the former w'ill oxi- 

 dize of the latter : 



* Poggend. Annal., 95, 217. 



