Clemens Winkler

“ The chemical individuality of radium remains almost entirely unknown; nevertheless it is constantly sought, especially in those regions where pitchblende deposits occur, and where they already dream of developing radium ores and a future radium industry. So far as known, the occurrence of radioactive substances is tied to that of uranium. This is in the highest degree surprising and can not be understood if we are to assume the presence of special elements. ”

“ Until now there has not been furnished any demonstration whatever that elements of high atomic weight, to which gold and platinum certainly must be counted, are polymers of elements of lower atomic weights, and that they decompose into such. The idea of a chemical element in the old sense remains still unshaken, and it will require much more thorough chemical experimental research than those produced thus far, to disturb it. ”

“ This seems to prove that the radioactivity does not keep pace with the concentration of the barium compounds, but lags far behind. A reliable measure of the radium-amount is not furnished. Even a preparation of 3,500 activity must have consisted mainly of barium chloride, since it yielded 140 for the atomic weight which is only slightly in excess of that of barium. As to the activity of the purest radium chloride, we find no statements, but it is said that the best radium preparations have an activity of 50,000 to 100,000 times that of uranium. ”

“ Lengyel who doubts the existence of radium, succeeded in making barium active by heating its nitrate with uranylnitrate, and Henry Becquerel prepared a strongly active barium sulphate by precipitating by sulphuric acid a barium chloride solution to winch uranyl chloride had previously been added; in this case the activity of the uranium compound had at the same time diminished. Further K. A. Hofmann and E. Strauss have obtained inactive fractions from active uranium compounds ”

“ Much more indefinite are the relations of the other radioactive substances thus far made known. The existence of polonium, discovered by P. and S. Curie, was for a time considered dubious, but seems to awake to new life in the radiotellurium of W. Marckwald. ”