370 SOCIETY OF PHYSICS AND NATURAL HISTORY OF GENEVA. 



biates fliscovered l»y Professor Mari£!;nac. An attentive study of the crystalline 

 forms has established their isomorphism both with these two categories of saline 

 products and with the bodies, such as the fluotitanates, in which the fluor is 

 completely substituted for the oxygen. The author has confirmed the fact 

 established by 51. JIarignac that the fluor replaces atom for atom the oxygen as 

 the isomorphous element. (Archives dcs Sciences, &c., t. xxx, p. 232. j M. Paul 

 de Gasparin (invited to one of our reunions) recounted to us (7th May) the prin- 

 ciples of the physical analysis of arable lands in the view of determining the rehi- 

 tivc proportions of gravel, sand, and clay which exist in the cultivated soil. But 

 this anal3-sis does not necessarily manifest the degree of fertility of a given soil, 

 for it cannot evince the very variable proportions of phosphoric acid, potassium, 

 magnesia, and other mineral substances which fulfil the functions of manures. 



§ 5. — MIXERALOGT AND GEOLOGY. 



M. dc Loriol (2d January) having, in company with M. Cotteau, studied the 

 Portlandian stratum of the department of the Yonne, has found it to be divided 

 into two zones : the lower one with but 13 fossil species and characterized by 

 the Ammonites f/igas, the upper with 110 species and characterized by the Pinna 

 sitperjur&nsis. The lower zone presents the remarkable fact of the intercalation, 

 in the midst of the limestone, of a thin marly bed filled with the Ostrca virgida. 

 The first strata of the middle neocomian rest immediately on the last Portlan- 

 dian strata. The zoological limit, however, is sharply defined ; no species is 

 common to the two faunas. Professor Favre ( 7th November) presented us his w'ork 

 in three volumes, entitled : lieclierchcs gcologiqiics dans les parties de la >avoie, 

 dii Fiemont ct de la Suisse, voisines du Mont-Blanc, (Geological researches in 

 the parts of Savoy, Piedmont and Switzerland, adjacent to Mont-Blanc,) with 

 an atlas of 32 plates. Proceeding in the traces of Horace de Saussure, Deluc, 

 Necker and other explorers, our colleague has brought a large contingent of 

 personal observations towards deciphering the enigma of the formation of the 

 Central Alps. The medal awarded to his geological chart of these countries by 

 the jury of the Exposition of 18G7, enables us to presage the reception which 

 the text that completes it will receive. The society may well congratulate 

 itself at seeing members like MM. de la Rive, Pictet, Boissier, de Candolle, 

 Favre, de Saussiu-e and others, employed in collecting in special works and in 

 a systematic form, not only their own numerous researches, btit those which 

 other savants have dispersed in memoirs and monographs. There cannot but 

 ensue from this a more precise statement of general results, a more exact view 

 of laws and their relative importance, a more certain classification, and a 

 more profound examination of obscure or doubtful points. Science is 

 advanced by being embodied in a systematic form. (Archives des Sciences, 

 &c., t. xxxi, p. 123. j M. Favre has, at different intervals, placed under 

 our eyes wrought silex and' fossil bones collected for some time past at dif- 

 ferent places on Mt. Saleve. The first discoveries go back to at least 1835 ; I 

 possess some pieces which I then met with in the caverns of Veyrier while 

 making botanical and geoloo'ical excursions. The specimens collected by our 

 colleague are implements of' flint mingled with the relics of the reindeer, atid 

 ascend to the most ancient period of the age of stone. He has seen a bone orna- 

 mented with a design which represents an animal, (probably a wild goat,) and 

 another bone on which a plant was carved. M. Favre computes that the 

 station of Veyrier is posterior to the glacial period, and that the reindeer then 

 abounded in our neighborhood as it now abounds in Norway. It was probably 

 in the facilite of Mornex, on the lesser Saleve, that the material was sought, at 

 that remote age, for executing the carved implements of Veyrier and the envi- 

 rons. Nothing, however, authorizes us to infer the existence of the human race 

 anterior to the glacial epoch. (Archives dcs Sciences, &c., t. xxxi, p. 246.^ M. 



