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THE POPULAR SCIENCE MONTHLY 



one inch to six feet six inches in thickness, 

 number 46 in the Warrior and 51 in the 

 Cahawba field. Two beds of black-band ore 

 characterize the Warrior measures, one of 

 them showing 43 per cent, of metallic iron ; 

 clay iron-stone is abundant, and is found in 

 all the Alabama coal-fields. In one instance 

 it forms the roof of a 28-inch bed of coal 

 in the Warrior measures. Immediately un- 

 der the mountain limestone of the car- 

 boniferous formation in the Upper Silurian, 

 a bed of fossiliferous hematite occurs. It 

 extends in a northern direction over 120 

 miles into Tennessee. In Jefferson County, 

 Alabama, its thickness is 28 feet. About 

 two or three miles east and west of this ore- 

 bed lie the coal-fields. For its entire ex- 

 tent throughout the State, and immediately 

 under it, are the limestones of the Silurian 

 formation, among which are many of the 

 purest and those best adapted for fluxing 

 iron from its ores. Geologically, in de- 

 scending order, next come the immense beds 

 of brown ore, comprising manganiferous 

 and fibrous limonite and mamillary and crys- 

 tallized hematite, from which hitherto nearly 

 all of the iron of Alabama has been pro- 

 duced. 



The Physical Properties of Gallium. 



The physical properties of gallium, as as- 

 certained by its discoverer, Lecoq de Bois- 

 baudran, who has prepared a decigramme 

 of nearly pure metal, are summed up as fol- 

 lows in the American Journal of Science: 

 Its fusing-point is about 29.5 Cent., so that 

 the heat of the hand liquefies it. When 

 liquid, it exhibits the phenomena of sur- 

 fusion to a remarkable degree. It has re- 

 mained liquid for more than a month, the 

 globule being frequently broken and re- 

 united by a steel blade in a room the 

 temperature of which often fell below the 

 freezing-point, Contact with a bit of solid 

 gallium, however, solidified it at once. Li- 

 quid gallium is very mobile, appears cov- 

 ered with a pellicle when exposed to the 

 air, and adheres strongly to glass. Only a 

 few degrees below its fusing-point the metal 

 is hard and remarkably tenacious ; but, like 

 aluminum, it may be cut with a knife. It 

 crystallizes with facility, crystal facets be- 

 ingdevelopedbytreatment with hydrochloric 

 acid. It does not oxidize at a red heat except 

 upon the surface, and does not volatilize. 



Its spark-spectrum gives the two well-known 

 bright lines of wave-length 417 and 403.1 ; 

 its flame-spectrum only the 417 line, and 

 this difficultly. Its density approximately 

 is 4.7, thus placing it, like its other physical 

 properties, between aluminum and indium. 

 Its atomic weight places it there probably 

 also. 



Death of Karl Ernst von Baer. The 

 eminent Russian zoologist, Karl Ernst von 

 Baer, died at Dorpat, November 28th, in 

 the eighty-fifth year of his age. He was 

 born at Piep, in Esthonia, in 1792 ; at the 

 age of eighteen he entered the University 

 of Dorpat, graduating four years later as 

 doctor of medicine. He then went to Ger- 

 many, and, at Wurzburg, became a pupil of 

 Dollinger, the eminent professor of physi- 

 ology and anatomy. This was the turning- 

 point in Yon Baer's career, and determined 

 the course of his future studies. In 1817 

 he became prosector at Konigsberg, and, 

 four years later, professor of zoology. In 

 1830 he returned home, having been elected 

 a member of the St. Petersburg Imperial 

 Academy. He conducted a scientific ex- 

 ploration of the northern shores of Russia 

 in 1837. Of his most celebrated work, 

 " The Development History of Animals," 

 the first volume appeared in 1828 and the 

 second ten years later. He was also the 

 author of numerous treatises on the zoolosv 



On 



and botany of Russia. His latest work was 

 an adverse criticism on the Darwinian the- 

 ory. 



The death of Alexander Bain, which 

 took place at Glasgow, January 2d, was 

 cabled to this country, and at once in- 

 terpreted as applying to the eminent Pro- 

 fessor of Logic in Aberdeen University, 

 who bears that name, and who is much 

 more widely known here than Alexan- 

 der Bain, the electrician, to whom the 

 dispatch referred. He was an inventor, 

 and made various important improvements 

 in telegraphy. He invented, or reinvented, 

 the method of making use of " bodies of 

 natural waters to complete the electric cir- 

 cuit by laying a single insulated wire be- 

 tween the given stations, having at each end 

 a metallic brush immersed in the water." 

 This principle was promulgated in a patent 

 of 1841. In 1846 he patented the electro- 



