GEOLOGY. 361 



VOLCAXIC EMANATIONS. 



The deficiency of our information regarding the gaseous products of Vol- 

 canoes seems to have induced the Academy of Sciences to send two of their 

 men of science Messrs. St. Glair Deville and Leblanc to Italy, on a special 

 mission to examine the gases which issue from, the volcanoes of that coun- 

 try. They were supplied with peculiar apparatus, made for the purpose of 

 collecting and preserving the gases, and partly for examining them on the 

 spot. The memoir containing the result of their investigations has been 

 made the subject of a report by three very accomplished members of the 

 Academy, Messrs. Dumas, Boussingault, and Elie de Beaumont. They 

 state that M. Deville and his associate were enabled by their apparatus to 

 collect gases over mercury, not only at the orifice of the volcano, but at great 

 J']tths in the vent; in the latter case by slender tubes, which were rapidly 

 closed by the blow-pipe. The gases they brought away and analyzed in 

 Paris, were from Vesuvius, the Phlcgrean Fields, one of the Lipari Isles ( Vul- 

 cano), and Etna. Mixed with the gaseous products they found much 

 heated air, more or less altered by the addition of gas or vapors, or the ab- 

 sorption of oxygen, which led them to believe that common air penetrates 

 into the vent of the volcano by a fissure, is exhaled by it, and escapes 

 heated. Generally, the report confirms the opinions of Davy as to Vesu- 

 vius, Boussingault as to the Andes, and Bunsen as to Iceland, but with 

 some additions. They show that different fumeroles of one volcano do not 

 yield the same gas, and that the gas from a single fumerolc is not always 

 the same. Further, the gas from the different fumeroles varies with their 

 distance from the eruptive crater, and varies also with the time elapsed 

 from the commencement of the preceding eruption. The report concludes 

 by expressing an opinion that the gaseous emanations, carefully analyzed 

 and compared, will throw light on the chemical processes which gave them 

 birth, and enable observers in the vicinity of a volcano, and, through them, 

 the surrounding population, to foresee the course which a coming eruption is 

 likely to run, and of course serve as a useful warning. 



NATIVE IRON. 



The following communication is made to Silliman's Journal, Sept. 1859, by 

 Dr. F. A. Genth : 



About four years ago I received, for examination, a mineral, \vhich was 

 said to be found in the neighborhood of Knoxville, Tennessee, in considera- 

 ble quantities, and which was believed to be a valuable nickel ore. A quali- 

 tative analysis of it, made at that time, proved it to be almost pure iron, and 

 the total absence of carbon, phosphorus, and sulphur, and its peculiar ap- 

 pearance, made it very probable that it was real native iron. The specimen 

 which I received was 1| x la in size; on one side of it the iron was one- 

 fourth, on the other one-eighth of an inch in thickness. On one side it was 

 incrusted by a silicate of iron, magnesia, and lime. 



The iron itself is of a grayish-white color, a hackly fracture, and breaks 

 easily into fragments of an irregular shape, which are crystalline, without, 

 however, showing signs of any distinct planes. It is soft, and scratches 

 fluorspar with difficulty. Lustre, eminently metallic. Dissolves readily in 

 nitric acid. It was found to contain - 



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