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FOEEIGN' COltllESPONDENCE. 
By Dr. T. L. Phipson, of Paris. 
Qeological Odours — Orcjanic Smells and Mineral Odours — Odour given 
out hy Black Limestone — Ozone produced hij Quartz — Hydrochloric 
Acid in Nature — Chlorine in ancient Volcanic Products — Sulphurous 
Acid and Sulphuretted Hydrogen — -Oases Devoid of Smell — Naptha 
present in Active Volcanos — Perpetual Burning Springs — The famous 
Asiatic Chimcera — A Fire that has Burnt fur Several Thousand 
Years — Gaseous Emanations of Tuscany — -Boracic Acid — Fumarolle 
and Lagoni—The Peat-logs of Suder-Brarvp — Errata. 
Our readers probably will not have forgottea 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 arayl), 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 
powerlul 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. Por 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 authraciferous strata, develope, when broken or scratched, a 
2 p 
