CHEMISTRY. (ATOMIC WEIGHTS.) 



137 



rent, complete reduction occurs, but the result- 

 ant metal combines, as in the case of tungsten, 

 with u largo quantity of carbon. It would ap- 

 pear, therefore, that at these high temperatures, 

 lhe-e refractory metals combine, with carbon to 

 form definite binary compounds. 



'1 IK; success of the Brin method of isolating 

 n indirectly from the atmosphere by the 

 y of barium peroxide has provoked at- 

 tempts to find other substances that will do the 

 \\ < nk !is well and cheaply. Superiority is claimed 

 by 1 1 err G. Kassner for calcium plumbate. His 

 method is first to expose this substance in the 

 form of spongy porous pieces to the action of 

 moist furnace gases, at a temperature not ex- 

 ceeding 100 C. The calcium plumbate under 

 these conditions rapidly absorbs the carbon di- 

 oxide contained in the furnace gases, and is 

 thereby decomposed with formation of calcium 

 carbonate and free peroxide of lead, and without 

 any change of form, the spongy pieces still re- 

 taining their shape and texture. The product 

 of this first operation, when fully saturated with 

 carbon dioxide, is transferred to a strong red-hot 

 retort, where oxygen is rapidly disengaged. When 

 the peroxide of lead has given up most of its 

 available oxygen, carbon dioxide is evolved and is 

 separated from the oxygen as long as that contin- 

 ues to go over by passing it over a further 

 quantity of calcium plumbate. The residue is 

 tiien, by driving a current of air through the 

 retort, reconverted into calcium plumbate for 

 use in another operation. In a plumbate of cal- 

 cium process patented by Peitz, pure carbon di- 

 oxide is used instead of furnace gases; and a 

 paper has been published on the subject by Le 

 Chatelier. 



A method of increasing the illuminating power 

 of coal gas by introducing pure oxygen into it 

 is to be adopted at the Huddersfield gas works, 

 England. It was suggested by Mr. Edward 

 Tathan, of Australia, in 1890, that a stable gas 

 of high illuminating power could be obtained by 

 adding oxygen to warm, heavy oil gas. The 

 fact was experimentally verified in the same 

 year by Dr. L. T. Thorne. Preparations have 

 since been made for practically testing the appli- 

 cability of oxy-oil gas to the enrichment of coal 

 gas, for which works have been erected at Hud- 

 dersfield and at Salisbury Square. London. 

 The oxygen is introduced into the oil gas by an 

 automatically adjusted arrangement soon after 

 it leaves the retorts and while it is still warm ; 

 the mixed gases then pass together through the 

 condensers. The oxy-oil gas is stored in special 

 holders, so arranged as to admit it into the coal 

 gas just before its entry into the station meter. 

 The results PO far obtained are highly satisfac- 

 tory, and still better have been realized at Salis- 

 bury Square. 



Osmium has been melted by MM. Joly and 

 Vezes, at the temperature of a very powerful 

 electric arc, in a similar manner to that in 

 which ruthenium is melted. To avoid loss of 

 metal by oxidation and the formation of the 

 poisonous volatile tetroxide, the operation is 

 performed in the electric furnace of Ducretet 

 and Lejeune. in which the metal is heated in a 

 carbon crucible placed in a closed chamber trav- 

 ersed by a stream of carbon dioxide, when it 

 melts at the requisite temperature without seri- 



ous volatilization. After fusion the element 

 presents a brilliant metallic surface, the blue 

 color of which is slightly tinged with gray. It 

 breaks with a crystalline fracture, and is dis- 

 tinguished by its remarkable hardness, exceeding 

 that of ruthenium and indium, and cuts glass 

 and scratches quartz. It also after fusion re- 

 tains its bright surface, apparently proof against 

 the attacks of atmospheric oxygen. All of the 

 refractory metals of the platinum family have 

 now been obtained in liquid form. Of them all 

 osmium is the most refractory, its melting point 

 being considerably higher than that of ruthe- 

 nium. It resembles that metal very much in 

 many of its properties, particularly in the ready 

 formation of a volatile tetroxide. It, however, 

 differs in aspect entirely from ruthenium, exhib- 

 iting a remarkable blue metallic luster, while 

 ruthenium is more white than platinum. The 

 six metals of the platinum group appear to re- 

 semble one another more particularly in pairs, 

 ruthenium and osmium having many physical 

 and chemical attributes in common ; rhodium 

 and iridium are similarly nearly allied, and pal- 

 ladium and platinum form the third parr. In 

 many. respects, however, osmium exhibits a pecul- 

 iar and somewhat isolated character, more akin 

 to that of the metalloid elements. Indeed, De- 

 ville and Debray termed it the metalloid of the 

 platinum group; Berzelius compared it to ar- 

 senic, and Dumas to tellurium. 



Atomic Weights. In a memorial paper on 

 Richard Servais Stas, read before the English 

 Chemical Society in December, 1892, Prof. J. W. 

 Mallet, after reviewing the work of that chemist, 

 particularly in the determination of atomic 

 weights and his inquiry concerning the possible 

 dissociation of the elements at high temperatures, 

 considered the objects to be aimed at and the 

 methods to be pursued in future work. He advo- 

 cated the repetition by competent hands of some 

 one at least of Stas's fundamental results, making 

 no distinction between rare and common ele- 

 ments, and aiming at the determination of the 

 atomic weights of all with the least possible delay 

 and the highest attainable degrees of accuracy. 

 Certain of the elements for example, tellurium 

 and cobalt particularly call for a more search- 

 ing and exact investigation of their atomic 

 masses. In a number of cases the accepted value 

 is based upon the investigation of only a single 

 interchange ; it is desirable that in such cases 

 other and independent methods should be re- 

 sorted to. It is eminently desirable that an at- 

 tempt be made to determine directly the ratio 

 of hydrogen to each of the halogens without 

 bringing in the atomic mass of oxygen. The 

 metals of the yttrium and didymium groups 

 should be further investigated. It is time that 

 the foundation be made for a more minute and 

 critical study of the periodic system of classifica- 

 tion, for which closer than the roughly approxi- 

 mate values hitherto used should be employed. 

 The author advocates the substitution of the ex- 

 pression "atomic mass" for "atomic weight,'' 

 as being a more precise term ; and he urges that 

 all atomic masses be expressed in terms of the 

 mass of the hydrogen atom taken as unity, 

 strongly objecting to the change advocated by 

 many to 0=16. 



Prof. Seubert has made a redetermination of 





