APEIL28, 1899.] 



SCIENCE. 



613 



that it will lead, perhaps with some modifi- 

 cations and extensions, to a more compre- 

 hensive theory of structure, and to a clearer 

 definition of the as yet onlj' vague concep- 

 tion of valencj'. It is the broadest gen- 

 eralization of inorganic chemistry since the 

 discovery of the Periodic Law, and shows 

 that inorganic chemists are no longer will- 

 ing to be mere imitators and to close their 

 eyes to the existence of whole groups of 

 bodies which do not tally with current 

 theories, and are beginning to see that in 

 these is to be sought the key to a broader 

 inorganic chemistry. 



The slow development of inorganic chem- 

 istry during the period from 1830 to 1865, 

 as compared with that of organic chemistry, 

 was due, as has been seen, in part to the 

 greater breadth and greater diversity of the 

 field, to the relative absence of leading ideas 

 and leading motives, and to the comparative 

 tractability of carbon compounds as com- 

 pared with inorganic compounds under the 

 restrictions of the experimental methods in 

 vogue. Front's hypothesis and allied spec- 

 ulations gave a working hypothesis for a 

 limited number of investigators, but the un- 

 certainty of the atomic weights, whifch in 

 part was conditioned by the imperfection of 

 analytical methods, prevented any satisfac- 

 tory results being reached. Absolute purity 

 of materials and absolute accuracy of 

 analytical methods are not of the first im- 

 portance to the organic chemist, to whom 

 errors of one or two points in the first deci- 

 mal are seldom of any significance. To the 

 atomic-weight chemist, on the contrary, 

 accuracy is the very first point to be con- 

 sidered ; not only must his material be abso- 

 lutely free from impurities, but his methods 

 must be beyond criticism, and it is only 

 with the increasing perfection of analytical 

 methods, admitting not only of quantitative 

 determinations of the greatest accuracJ^ but 

 also of the detection of traces of impurities 

 which for ordinary purposes are negligible, 



that this kind of work has oifered induce- 

 ments to a large number of workers. The 

 long-wanting, leading idea or motive has 

 been in large part furnished by the Periodic 

 Law. The comparison of the chemical and 

 physical properties of the elements and 

 their compounds, the search for new ele- 

 ments, the fuller investigation of those al- 

 ready known, with the view of more firmly 

 establishing their place in the system, and 

 the redetermination of the atomic weights, 

 are evidence of its influence. Witness, for 

 example, the great activity in the subject of 

 the rare earths, the work on the relative 

 position of nickel and cobalt in the system, 

 and the investigations of the atomic weight 

 of tellurium, having for their object the 

 decision of the question whether this ele- 

 ment actually has an atomic weight greater 

 than that of iodine, as the best determina- 

 tions thus far seem to indicate, or whether 

 it is less, as its chemical analogy to sulphur 

 and selenium requires. 



Organic chemistry, with its limited range 

 of temperature, is essentially a chemistry of 

 the beaker, the Liebig condenser and the 

 bomb oven ; it demands but comparatively 

 simple and cheap apparatus of glass, not 

 calculated to withstand high temperatures, 

 and as such is within the means of the 

 humblest laboratory. The reverence of the 

 organic chemist for the platinum crucible 

 is something astounding. With improve- 

 ments in apparatus for producing and ma- 

 terials for resisting high temperatures, new 

 vistas have opened to the inorganic chemist, 

 while the province of the organic chemist, 

 limited as it is by the instability of his com- 

 pounds, has derived no benefit therefrom. 

 iNot only do we owe to this the beautiful in- 

 vestigations of Victor Meyer and others on 

 high-temperature vapor densities, but with 

 the recent development of electrical technol- 

 ogy the electric furnace has appeared, and 

 with it a new chemistry, the chemistry of a 

 temperature of 3,500° C. Not only have new 



