1104 



well-crystallized preparations : however these crystals had microsco- 

 pical dimensions and were only little adapted for goniometrical measure- 

 ments, because they were intergrown with each other in a chaotic 

 mass. However it was possible to prove, that no relation in the 

 crystallographical architecture of these crystals with that of the ethyl- 

 sulphates of (he also trivalent rare earth-metals exists. These salts 

 are of monoclinic symmetry, and they possess characteristic optical 

 properties, which can be considered as most typical for them. In the 

 subjoined table the principal data are put together. 



From this review it follows, that the beryllium-ethylsulphate evidently 

 must be placed in an isolated place, with respect to all other 

 ethylsulphates. It is tetragonal and possesses a very deviating chemical 

 composition, being a basic salt oi \\\q ïovmnl-a.-. Be 0. Be{SO^.C^h^) -\- 

 -\-^H,0; analysis gave: U,dy,BeO. 



§ 8. Because evidently the above mentioned salts of indium and 

 scandium were little adapted for measuring purposes, the corresponding 

 acetylacetonates were prepared. The acetylacetonates of the metals 

 of the rare earths crystallise ahvays like felty, fine needles, which 

 are not exactly measurable. On the contrary, the acetylacetonates of 

 the trivalent metals: scandium, alwuinium, indiumsind iron crystallise 

 in big, flat crystals, which immediately show themselves closely 

 related to each other, but widely different from the salts of the first 

 mentioned series. The measurements really prove, that the salts of 

 scandium, iron, and indium are directly isomorphous with each other, 

 while the aluminiumsalt must stand to them in the relation of 

 isodimorphy. With the trivalent gallium, all those metals must there- 

 fore be placed into the same group ; evidently they are not imme- 

 diately related to 'the rare earth-metals. Thus also the question, if 

 the element scandium, must be placed among the rare earth-metals, 

 can be answered in the negative, as well with respect to arguments 

 formerly adduced from several sides, as with respect to the facts 

 described here ^). 



The heryUium-acetylacetonate is monoclinic, and, generally speaking, 

 very widely different from the other acetylacetonates. This substance 

 is a highly remarkable object for optical demonstrations : with enor- 

 mous values for its dispersion, it shows the phenomenon of the 

 crossing of axial planes, like the mineral hrookite ; but in agreement 

 with the monoclinic symmetry, the effect of the dispersion of the 



') See about lliis question however the just publislied paper of R. J. Meyer, 

 (loco cit.). In my opinion tiie claimed analogy (p. 268) between scandium and 

 yttrium can hardly be defended in a persuading way. 



