Notices and Extracts fro7n the Minutes of the Geological Societt/. 333 



lization upon contact with air,, makes it impossible to preserve specimens of 

 the g-ypsum witii crystals of that salt^ as the latter effloresces and conveys (par 

 epigynie) the incorrect idea of a saline formation. I only succeeded in pre- 

 serving them from falhng into powder,, by inclosing them^ at the moment of 

 their removal from the gypsum^ in tubes or glass phials well corked. 



The range of this saliferous formation makes a portion of the southern face 

 of the Jura. It is stratified in beds extending from N.W. to S.E. in an oblique 

 position^ at angles varying to 90° rising towards the N.E. The dip of the sa- 

 liferous gypsum is from 70° to 80°. This formation is the eighth in the series 

 of rocks composing the southern slope of the Jura, beginning with the shelly 

 conchoidal limestone {calcaire conchoide coquille) which constitutes the ex- 

 terior envelope. 



The geognostic description of the Jura not being the object of this notice, 

 I confine my observations to those rocks between which the gypsum and the 

 crystallized sulphate of soda are placed. Their position is between beds of the 

 same quality of gypsum nearly vertical, and containing no salt, and which 

 overlie other beds of secondary limestone. This last is granular, shelly, ca- 

 vernous, and without fossils ; its stratification is conformable. Above the gyp- 

 sum is the formation of black aluminous foliaceous marl charged with sul- 

 phuret of iron, and having several beds of marly and shelly carbonate of lime 

 alternating. 



Mineralogical writers make no mention of sulphate of soda, because that 

 salt has never been found crystallized and in abundance in rocks of any known 

 mountains, (montagnes hien connues,) although it has been met with some- 

 times mixed with hydrochlorate of soda, and most frequently in volcanoes*. 



The discovery of its existence in the gypsum of Muhlingen is interesting 

 in a geological point of view, and because it renders henceforward superfluous 

 the hypothesis of Klaproth explanatory of the origin of that salt in mineral 

 waters. That celebrated chemist attributed its presence to the decomposition 

 of hydrochlorate of soda by sulphuric acid disengaged in the bowels of the 

 earth from sulphuret of iron or from the combustion of sulphur. This suppo- 

 sition, although purely imaginary, has been so received, that the scientific 

 Berzelius repeats it in his interesting observations upon the waters of Carls- 

 bad. It is possible that it may some day be confirmed by observation, — with- 

 out which there is no science ; for truth consists in facts, and not in opinions. 

 However, as we now know that crystallized sulphate of soda exists in the heart 



* Haiiy has described the muriate, the borate, and the carbonate of soda, and has not men- 

 tioned the sulphate. Leonhard only speaks of the efflorescences of this salt. 



