Geological Society. Sff|5 



sulphate of carbyle, as is well known, being decomposed by water 

 into isaethionic acid. 



As acetamide differs from acetonitrile only in containing two 

 additional equivalents of water, it undergoes with Nordhausen sul- 

 phuric acid a strictly analogous transformation. 



From the comparative facility of its preparation it offers peculiar 

 advantages for procuring the methylotetra- sulphates. The only 

 difference to be noted is, that in this case the ammonia salt is gene- 

 rally eliminated instead of the free acid. 



M. Melsens, in his researches upon the sulphacetates, appears in 

 some sort to have anticipated the existence of the methylo-tetra- 

 sulphates. He remarks that he once found in the mother liquor 

 obtained from the preparation of sulphacetate of silver, a crystalline 

 salt, the composition of which he represents by the formula 



L. ^2 H^ Ag, S, O,,. 



It is evident that these crystals contain the same elements as 

 methylo-tetra-sulphate of silver, but M. Melsens does not appear to 

 have investigated the subject further than by showing the existence 

 of this silver salt. 



A detailed description of the methylo-tetra-sulphates, and the 

 study of the corresponding bodies of other series, will be on our 

 part the subject of a special memoir. 



if^. 



b; 



* , GEOLOGICAXi SOCIETY. 



[Continued from p. 482.] 

 January 23, 185G — W. J. Hamilton, Esq.,Pres. G.S., in the Chair. 



The following communications were read : — 



1. "On the Cryolite of Greenland." By J. W. Tayler, Esq. 

 Communicated by J. Tennant, Esq., F.G.S. 



At Evigtok, on the shore of the Fiord of Arksut, in South Green- 

 land, is a mass of Cryolite, 80 feet thick, 300 feet long, and dipping 

 southward, at an angle of 45°, between two planes of the including 

 gneiss, to an unknown depth. The upper or roof gneiss is separated 

 from the Cryolite by a thin layer of quartz-crystals, and a rich vein 

 of argentiferous galena, associated with some copper- and iron- 

 pyrites and sparry iron-ore. The same minerals, together with fine 

 crystals of tantalite, are diffused on the upper part of the Cryolite 

 to the depth of a few feet. The mass of Cryolite is quite pure until 

 within 10 feet of the under or floor gneiss, Avhen again similar mine- 

 rals are disseminated in it. The Cryolite is separated from the undef 

 gneiss by a vein of dark purple fluorspar. 



The central Cryolite mass, wlien exposed at the surface (to which 

 the sea has access), is quite white ; but, when penetrated to a depth 

 of 10 feet, although free from other minerals, it is of a darker colour, 

 and at 15 feet depth becomes nearly black and more translucent 

 than the outer portion of the mass or bed. 



