192 THE ATOMIC WEIGHTS. 



grammes to the litre. With this, solutions containing 

 known quantities of antimony or of antimony compounds 

 were titrated, the end reaction being adjusted with a stand- 

 ard solution of ferrous chloride. In some cases the titration 

 was preceded by the addition of a definite weight of potas- 

 sium chlorate, insufficient for complete oxidation ; tlie an- 

 hydrochromate then served to finish the reaction. The 

 object in view was to determine the amount of oxidizing 

 agent, and therefore of oxygen, necessary for the conver- 

 sion of known quantities of antimonious into antimonic 

 compounds. 



In the later paper Kessler refers to his earlier work, and 

 shows that the values then found for antimony were all too 

 high, except in the case of the series made with tartar 

 emetic. That series he merely states, and subsequently 

 ignores, evidently believing it to be unworthy of further 

 consideration. For the remaining series he points out the 

 sources of error. These need not be rediscussed here, as the 

 discussion would have no value for present purposes ; suffice 

 it to say that in the series representing the oxidation of 

 SbgOg with anhydrochromate and chlorate, the material 

 used was found to be impure. Upon estimating the im- 

 purity and correcting for it, the earlier value of Sb = 123.80 

 becomes Sb = 122.36, according to Kessler's calculations. 



In the paper now under consideration four series of results 

 are given. The first represents experiments made upon a 

 pure antimony trioxide which had been sublimed, and which 

 consisted of shining colorless needles. This was dissolved, 

 together with some potassium chlorate, in hydrochloric acid, 

 and titrated with anhydrochromate solution. Six experi- 

 ments were made, but Kessler rejects the first and second as 

 untrustworthy. The data for the others are as follows : 



From these figures Kessler deduces Sb = 122.16. 



