152 SMITH— COLUMBIUM AND TANTALUM. [April i 3) 



chett and tantalum of Ekeberg) in that he announced the existence 

 of ilmenium ; but it was not generally accepted by chemists. Her- 

 mann, however, persisted in his declaration that it occurred along 

 with the other two elements to which reference has been made. v. 

 Kobell believed that he had detected dianium in allied minerals. 

 This unfortunate state of affairs prevailed until the early sixties, 

 when Marignac, after a careful study of a number of minerals from 

 various localities, announced the existence in them of but two ele- 

 ments — the columbium of Hatchett and the tantalum of Ekeberg 

 — and added that the confusing reactions which had perhaps led 

 Heinrich Rose — but most certainly, Hermann and von Kobell — 

 astray were to be explained by the presence of titanium in all tan- 

 talites and columbites. It is only fair to say that Marignac never 

 succeeded in obtaining titanium from any one of the minerals in 

 which, according to him, it occurred, associated together with 

 columbium and tantalum. Indeed, in his concluding paper on 

 columbium he frankly acknowledged that the columbium com- 

 pounds, which he used for the determination of the atomic weight of 

 the metal, contained titanium, and that he knew of no method by 

 which the latter could be separated from columbium. Marignac's 

 conclusion was accepted by the chemists of the world as final. 



When we come to examine the evidence which Marignac gives 

 for the presence of titanium, we find that it is, practically : that 

 the recrystallization of a double fluoride of columbium and potas- 

 sium, supposed to contain titanium, gave rise, gradually, to a frac- 

 tion which became more insoluble in water and the molecular 

 weight of its acid oxide approached, within ten or more units, 

 that required by titanic oxide. It is well to bear in mind that 

 at no time did Marignac, whose ability and keen insight one would 

 not for a moment question, give any tests which are ordinarily 

 regarded as indicating titanium. He assumed it to be present on 

 the evidence mentioned above, viz : the greater insolubility of 

 the double fluoride and an approximate molecular weight corre- 

 sponding to that required by titanic oxide. Ever since Marignac's 

 day chemists the world over have tacitly accepted titanium as asso- 

 ciated with columbium in columbites. They have also estimated 

 its quantity by methods suggested from time to time. One of these 

 methods is based on the color reaction which titanium salts give 

 with hydrogen peroxide. Its intensity, compared with that shown 



