120 



THE GEOLOGIST. 



FOREIGN CORRESPONDENCE. 



By Dr. T. L. Phipson of Paris. 



Arsenic in Lignite and Bituminous Limestone, (Soc. — Professor Dauhree^s 

 Researches — Subterranean Noises — The Oldest Fossil Mammalia — A 

 New Fossil Saurian. 



Some years ago, M. Daubr^e searched for arsenic and found it in 

 many different kinds of rocks ; but more especially in the mineral 

 combustibles belonging to different strata.* He found at that time 

 that the tertiary lignite of Lobsann (Bas-Rhin), was uncommonly rich 

 in arsenic : certain samples of this lignite were found to contain as 

 much as from 0.002 to 0.008 of their weight of arsenic. 



These observations have just been confirmed by the same eminent 

 geologist, under certain circumstances that deserve to be made known. 

 A limestone strongly impregnated with bitumen alternates with the 

 lignite of Lobsann. This limestone forms the principal element of 

 the bituminous mortar (mastic) employed in the locality for different 

 constructions. For some years it has been employed also to obtain 

 certain pyrogenous oils, which are produced by a process of distil- 

 lation. When the alembics which have been used in this distillation 

 are taken down, the interior of the tube through which the oils distil 

 is often seen to be encrusted with a curious deposit, produced by the 

 gradual condensation, outside the furnace, of certain volatile sub- 

 stances. This deposit, or sublimation, was found, upon examination, 

 to be pure arsenic, crystallized in rhombohedrons ; it attains sometimes 

 as much as two centimetres in thickness, and in the course of some 

 months, it will completely obstruct the necks of the retorts. The 

 arsenic thus deposited forms about the one-millionth part in weight 

 of the rock which is submitted to distillation. 



The arsenic contained in the limestone is not entirely condensed 

 in this manner ; a notable quantity distils over with the oils, as 

 M. Daubree assured himself by a special investigation. In what 

 state of combination the arsenic exists in these oils has not yet been 

 ascertained ; it is well to be aware, however, that arsenic does exist 

 in them, as they are constantly employed for burning in lamps, &c. 



The state in which this arsenic exists in the limestone of Lobsann, 

 has, however, been ascertained with certainty by M. Daubree, and in 

 a very ingenious way. By the use of an appropriate solvent, the 

 bitumen is dissolved out of the limestone ; then the carbonate of 



* See his Rcchcrchcs sur la presence deV arsenic dans Ics ConibustiUes mineraux, 

 dans divcrses rochcs, ct dans V can dela mer. {Annales des Mines, 4:* serie, torn. 

 xix. p. ()69.) An extract was also published in the Comptes-Rendus 'de TAcad. 

 de Sc. Paris, xxxii. p. 827. 



