154 



SCIENCE. 



[N. S. Vol. XI. No. 265. 



NOTES ON INORGANIC CHE3IISTRY. 

 In a recent number of the Journal fiir Oasbe- 

 leuchtung an account by M. van Breukeleveen 

 and A. ter Horst is given, taken from Set Oas, 

 of serious trouble from the formation of iron- 

 carbonyl in water-gas mains. This Dutch 

 works manufactures uncarburetted water-gas 

 for use in Welsbach burners, and it is found 

 that in a short time the mantel of the burner 

 loses all its brilliancy owing to the deposition 

 of a brown substance, which micro-chemical 

 analysis proved to be iron. This proved to 

 have been deposited from the iron-carbonyl 

 formed, not in the process of manufacture of 

 water-gas, but in its passage through the cold 

 iron pipes, at ordinary pressure. The only 

 practical remedy seems to be coating the in- 

 terior of the pipes with tar. A similar deposit 

 is often noticed on the lines used in the Drum- 

 mond light, where instead of hydrogen, com- 

 pressed water-gas or even coal gas in steel or 

 wrought iron cylinder is used. Here the only 

 remedy for the diminishing of the light consists 

 in turning the lime quite often. 



In the following number of the Journal 

 Broockmann takes up the old problem of the 

 gases contained in bituminous coal. At 100° E. 

 von Meyer found a maximum of 238 cubic centi- 

 meters gas given off from 100 grams of coal, 

 while Bedson found as high as 818 cc. The great 

 variation in quantity as well as in composition 

 is ascribed, in part at least, bj' Broockmann to 

 the presence of more or less atmospheric air. 

 He himself worked with a Sprengel vacuum 

 which was kept with repeated warming for 

 three days before the coal was heated, a tem- 

 perature of 100° then being used. In this way 

 a number of Westfalian coals gave from 7 to 

 150 cubic centimeters per hundred grams, an 

 English coal 70 cc, a lignite from Habicbts- 

 wald 50 cc. The gases obtained were generally 

 chiefly methane with more or less carbon di- 

 oxid. Higher hydrocarbons, carbon monoxid, 

 and oxygen were rarely present and then only 

 in small quantities. One of the Westfalian 

 coals gave little methane, more carbon dioxid, 

 and over 60 per cent, of nitrogen. Two Ober- 

 schlesian coals gave a mixture of carbon dioxid 

 and nitrogen, and the lignite gave 91 per cent. 



carbon dioxid and nine per cent, carbon mon- 

 oxid. When heated with air in a closed tube to 

 160°-200° the oxygen of the air is completely 

 absorbed, leaving only nitrogen with a very 

 little carbon dioxid. 



The precipitation of gold by iron pyrites is 

 investigated by P. V. Gladkov in the Berg- und 

 Hiittenmannische Zeitung. A solution of gold 

 chlorid is completely precipitated by filtering 

 through a layer of pyrites ; if the pyrites carry 

 copper, this and not iron replaces the gold in 

 solution. The reduction takes place in pyrites 

 which have been carefully washed by acid and 

 hence is caused by the sulfld and not by any 

 ferrous sulfate which might have been formed 

 by weathering. The gold is precipitated not 

 as sulfid, but as metallic gold, as is shown by 

 the fact that it can be amalgamated with mer- 

 cury. This study has considerable bearing on 

 the treatment of pyrite ores of gold. 



J. L. H. 



CURRENT NOTES ON PSYSIOGRAPHY. 

 THE CHATTANOOGA DISTRICT. 



The ' Physiography of the Chattanooga dis- 

 trict, in Tennessee, Georgia and Alabama' is 

 elaborately discussed by C. W. Hayes (19 Ann. 

 Rep., U. S. G. S., Pt. II., 1-54, 5 colored 

 maps). The mountains of post-Carboniferous 

 deformation were reduced in Cretaceous time 

 to a broad peneplain (the Cumberland) with 

 scattered or grouped monadnocks; ' unakas' be- 

 ing suggested as a name for grouped residuals. 

 General uplift of the region allowed the de- 

 velopment a less extensive peneplain (the 

 Highland-Eim) probably in Eocene time ; and 

 a still later uplift permitted the excavation of 

 the present valley floors in Neocene time. 

 The peneplains are referred to subaerial in- 

 stead of to marine denudation, after a critical 

 review of their origin. Special consideration 

 is given the development and adjustments of 

 the drainage system ; the chief streams first 

 flowed westward into an interior sea ; then 

 southward along the troughs of Appalachian 

 deformation ; then westward again as a result 

 of the shifting of divides by stream action 

 chiefly in the first and second cycles of grada- 

 tion. It is pointed out that the Tennessee may 

 in the future be once more turned southward 



