554 



SCIENCE 



[N. S. Vol. XXVIII. No. 721 



molybdenum and tungsten by treatment 

 with copper silicide or by fusing the oxides 

 with silicon dioxide and aluminum is im- 

 portant. The interest which tungsten has 

 aroused during the past five years is partly 

 shown by an increase of 500 per cent, in 

 the number of articles reviewed in 1907 

 over 1903. 



Uranium and its ores, i. e., pitchblende, 

 carnotite, autunite, etc., seem to owe their 

 chief prominence at present to the radio- 

 active material associated with them, al- 

 though uranium salts are used in the man- 

 ufacture of certain velvety-black pottery 

 glazes and greenish-yellow iridescent glass- 

 es. An interesting subject for further 

 analytical work is the separation of uran- 

 ium and vanadium in carnotite; a com- 

 mercial process with this end in view has 

 recently been developed by Haynes and 

 described in the last volume of "Mineral 

 Resources. ' ' The chief source of uranium 

 in this country is the carnotite deposit of 

 Colorado. 



The element selenium has the peculiar 

 property of being, under the influence of 

 light, a fairly good conductor of electricity, 

 while in the dark it is practically a non- 

 conductor. In the latest edition of "Min- 

 eral Resources of the United States, ' ' Hess 

 mentions the following purposes for which 

 this property of selenium has been used in 

 the construction of apparatus, namely: for 

 automatically lighting and extinguishing 

 gas buoys, for exploding torpedoes by a 

 ray of light, for telephoning along a ray 

 of light, for transmitting sounds and pho- 

 tographs or other pictures to a distance by 

 means of telegraph or telephone wire, for 

 measuring the quantity of Roentgen rays 

 in therapeutic applications. Upon a more 

 general demand for any or all of these in- 

 struments depends very largely the demand 

 for selenium. Up to the present time there 

 has been practically no production of 



selenium in the United States outside of 

 small quantities existing in residues result- 

 ing from the refining of copper by electro- 

 lytic methods. The recent work upon 

 selenium has been largely in the line of the 

 formation of new compounds. A mono- 

 graph by Marc° upon the "Physical and 

 Chemical Properties of the Element" has 

 recently appeared. 



If the element tellurium had no other 

 reason for prominence, its anomalous 

 atomic weight and its mineralogical asso- 

 ciation with gold would serve to give it an 

 important place. Lenher in a recent ar- 

 ticle has briefly discussed about forty years 

 of combined work by Brauner, Baker and 

 Bennett, Norris and himself upon the 

 "Homogeneity of Tellurium," and has 

 arrived at a conclusion in favor of homo- 

 geneity and of an atomic weight of 127.55. 

 About the same time Marcwald reached a 

 similar conclusion regarding homogeneity, 

 but gave as the result of his work an atomic 

 weight of 126.85, a value slightly below the 

 accepted weight of iodine, 126.97. Marc- 

 wald 's method was the heating of ortho- 

 telluric acid (HeTeOe) and the weighing 

 of the tellurium dioxide obtained. 



The close association of tellurium with 

 gold has, as already intimated, brought 

 about its possibly unenviable prominence. 

 A careful study of the problems connected 

 with the satisfactory handling of telluride 

 ores has recently been published by Hille- 

 brand. 



One can scarcely speak of the growing 

 prominence of such elements as gold and 

 platinum, but a few figures in regard to 

 their production in our country may be in 

 point. The output of gold in 1906 was 

 $94,000,000 as against $74,000,000 in 1903, 

 and the output of platinum in 1906 was 

 valued at $45,000 as against $2,000 in 1903. 



* " Die Physikaliscli-Cliemischen Eigenschaften 

 des metallischen Selens," Hamburg and Leipzig, 

 Leopold Voss, 1907. 



