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FOUEIGN COKEESPOKDEI^CE. 



By Dr. T. L. Psipsoj^, of Paris. 



Geological Odours — Organie Smells and Mineral Odours — Odour given 

 out hj Black Limestone — 0%one produced ly Quartz — JECydrochloric 

 Acid in Nature — Chlorine in ancient Volcanic Products — Sulphurous 

 Acid and Sulphuretted Hydrogen — Gases Devoid of Smell — Naptha 

 present in Active Volcanos — Perpetual Burning Springs — TJie famous 

 Asiatic Chimoera — A Fire that has Burnt for Several Thousand 

 Years — Gaseous Emanations of Tuscany — Boracic Acid — Fumarolle 

 and Lagoni-^The Peat-hogs of Suder-Brarup — Errata. 



Our readers probably will not have forgotten the account we laid 

 before them in May last, concerning the odour of the antediluvian seas. 

 Geological odours, or odours emitted naturally from rocks or minerals, 

 are interesting on this account — that they are not common. "We are 

 speaking, of course, of characteristic odours. Indeed, hardly a rock or 

 stone exists but which, having condensed in its pores certain gases, 

 emits them with their peculiar olfactive properties, when breathed 

 upon or when wet. Thus, many persons have doubtless, like ourselves, 

 had frequent occasions to remark the peculiar odour which arises 

 suddenly from the earth in the country roads, as well as in the streets 

 of our cities, the moment a heavy summer-shower of rain begins to fall. 



In organic nature odoriferous substances are very abundant, and 

 many of them have actually been produced artificially by modern 

 chemists. This is true, for instance, of the sweet essence of bitter 

 almonds, the flavour of the apple (valerianate of amyl), of the pear 

 (acetate of amyl), of pine-apple (butyrate of amyl), the strong- 

 smelling oil of garlic (sulphate of allyl), &,c. But, in the mineral 

 kingdom, only a very few natural species may be distinguished from 

 others by the aid of the olfactory nerve. Certain natural bituminous 

 substances (and here we fall again into the organic world), such as 

 naphtha, petroleum, &c., may be recognized by their peculiar smell ; 

 and among the strictly inorganic mineral species, sulphurous acid, 

 hydrosulphuric acid, chlorine, and hydrochloric acid are the most 

 powerful odorous substances known. 



When mineral substances are acted upon chemically, the presence of 

 many may be ascertained with certainty by the odours they then give 

 rise to. Eor instance, arseniferous minerals, and compounds of sele- 

 nium, which, when heated on charcoal before the blow-pipe, give out 

 an unmistakeable smell of garlic and rotten cabbage; or, again, certain 

 sulphides, when acted upon by a strong acid, evolve sulphuretted 

 hydrogen ; certain chlorides which, in the same circumstances, evolve 

 hydrochloric acid, &;c. 



We have heard many persons speak of the smell of sulphur. Pure 

 sulphur has little or no smell at all ; but, when burnt in the air, it develops 

 sulpurous acid, the pungent odour of which brings tears into the eyes. 

 Certain black and dark-coloured limestones, particularly those of the 

 coal and anthraciferous strata, develope, when broken or scratched, a 



2 p 



