184 Pbilomatic Society* 



he found no change to be made in the old laws ; becaufe the 

 fecondarv incidences which he had determined in the fup- 

 pofition of a cuhe, differed only half a degree from thofe 

 refulting from the rhomboidal form. This, fays the author, 

 is one of thofe cafes where a quantity very fenfihle of itfelf 

 is diminiftied by palling into certain refults which depend 

 on it. 



It arifes from thefc refearches, that all the iron ores which 

 retain a metallic appearance may be reduced to two kinds, 

 very dilti net from each other; one of which contains fub- 

 ftances that crvftallife in regular o6f.aedra, fuch as the iron 

 ofCorfica; and the other, thofe having for their primitive 

 form a rhomboid fomewhat acute, as the iron of the ifland 

 of Elba, that of Framont, and that of volcanoes. The 

 firft will continue to be diftinguiihed by the name of oxi- 

 dulatcd iron, and the fecond will be called oligijl iron ; that 

 is to fay, little abundant in iron in the metallic ftate. It is 

 here feen, that a greater quantity of oxygen imprints on the 

 primitive form a character entirely peculiar, by making the 

 regular o£taedron pafs to the rhomboid; and this feems to 

 indicate two very diftiiwft points of equilibrium, which 

 chemiftry no doubt will determine when it has carried the 

 analvfis of iron ore to a degree of correftnefs, fuited to that 

 perfection which this fcience has already attained. 



PHILOMATIC SOCIETY. 



C. De Sauffurc, the fon, read lately before this Society a 

 memoir on the influence which the foil has on certain con- 

 ftituent parts of vegetables. It was formerly believed that 

 the foil had no influence on vegetables, but in proportion 

 to the faculty it poflcfied of retaining a greater or lefs quan- 

 tity of moilture; and it was to this caufe alone that the 

 difference between the abundance and fize of vegetables 

 growing in calcareous foil, and the fame qualities in thofe 

 found in granitic foil, was afcribed. But Saufiure having 

 remarked that the animals which live in the calcareous 

 lands, that produce thefe vegetables, were larger, fatter, and 

 gave a greater quantity of milk, richer in butyraceous and 

 cafeous parts, than thofe in granitic diftricts, conceived an 

 9 idea 



