26 



SCIENCE. 



[N. S. Vol. XII. No. 28 



other KjEuCl^ , the former corresponding to 

 the type found in osmium and rhodium, the 

 latter to that found in platinum and palla- 

 dium as well as in iridium and osmium. In 

 describing this latter salt, Clans shows that 

 it was in the hands of Berzelius and prob- 

 ably in a pretty pure state, but that great 

 chemist thought it to be an iridium salt, 

 Berzelius was not convinced, and in the 

 ' Handworterbuch der reinen und ange- 

 wandten Chemie,' edited by Liebig, Pog- 

 gendorff and Wohler, the work of both 

 Berzelius and Clans is given. This was 

 naturally somewhat irritating to Clans and 

 he writes : * " Even if reverence for the 

 great authority of the great chemist (Ber- 

 zelius) should seem to justify such a course, 

 regard for the truth of science should not 

 have permitted it." The subject was now 

 dropped and for a third of a century no one 

 had worked upon this chlorid, when Pro- 

 fessor A. Joly, of the I'Ecole JSTormale, be- 

 gan his study of the platinum metals, and 

 much of the work of Claus upon ruthenium 

 was revised. ISTow it appears that not only 

 Berzelius, but also Claus himself was mis- 

 taken, and what he had taken for a chlor- 

 ruthenate, K2^'J^Cllg, was in a reality a 

 nitroso chlorruthenate, ILn^nCl^'NO. My own 

 work of a little later date upon the chlorids 

 of ruthenium abundantly confirmed this. 

 Many efforts were made to prepare a tetra- 

 chlorid of ruthenium but it proved elusive. 

 It may be noted in this connection that the 

 cesium and rubidium nitrosochlorids exist 

 in an anhydrous as well as in a hydrated 

 form and while the very easily soluble hy- 

 drated salts lose their water on warming 

 the solution, the very slightly soluble an- 

 hydrous salt being precipitated, the reverse 

 change is seemingly impossible, as the an- 

 hydrous salt will not take up water and 

 pass back into the hydrated form. 



The history of the higher chlorid of 

 ruthenium is not yet completed. Within 



*£un. Akad. St. Petersb. (2), 108, 1 (1860). 



the past year Professor Ubaldo Antony and 

 A. Lucchesi, of the University of Pisa, 

 have described * the preparation of the real 

 tetrachlorid, KjRuClg, which like the corre- 

 sponding salts of platinum and the other 

 metals of the group, crystallizes in octahedra. 

 I have more recently by methods similar to 

 those of Antony, prepared the cesium salt, 

 Cs^RuClj, which also crystallizes in octahe- 

 dra and corresponds to Antony's salt ; and 

 I have also been fortunate enough to obtain 

 a new salt of a rare type, lying intermedi- 

 ate between the tetroxide and the tetra- 

 chlorid, Cs,EuO,Cl, (2CsCl, EuO.Cl,). Now 

 a question may arise here as to whether 

 Claus was after all, wrong in believing he 

 had the tetrachlorid. As the salt was com- 

 monly made by Claus, by the action of nitric 

 acid, it was, without question, a nitroso- 

 chlorid, and his description corresponds 

 completely ; but Claus adds in a footnote f 

 that it is also possible to prepare the salt 

 by heating the trichlorid with potassium 

 chlorate and hydrochloric acid. This could 

 not give the nitrosochlorid, but while under 

 these conditions the tetroxid is usually 

 formed, it is possible that the tetrachlorid 

 may also have been formed. In another 

 place he speaks of making it by action of 

 hydrochloric acid on potassium ruthenate, 

 but in the presence of saltpeter. Except 

 for this latter salt, this is the method of 

 Antony, but usually at least it gives the 

 trichloride. The salt which Claus gener- 

 ally describes is the nitrosochlorid, but in 

 one place | he says the salt seems to be 

 dimorphous, for after crystallizing out the 

 common prismatic crystals (of the nitro- 

 sochlorid) he, on one occasion, obtained 

 large regular octahedra, isomorphous with 

 tetrachlorids of the other platinum metals. 

 As the molecular weight of the nitroso- 

 chlorid is almost the same as that of the 



* Gazz. cliim. ital., 29 i (1899). 



"^J.prakt. Chem., 39, 96 (1846). 



tBull. Akad. St. Petersh. (2), 1, 105 (1860). 



