160 Mineralogical Notices. 



though not by itself, by mere composition with a motion of 

 translation may be made to pass into one for which udx + &c. is 

 not integrable even by a factor, it follows that motions of the 

 former kind do not possess any physical characteristic by which 

 to distinguish them from their fellows of the class for which udx + 

 &c. is not an exact differential. This is the " remark " for the 

 sake of whichj partly, the second argument was introduced. 



I am prepared to maintain that, even if the second axiom were 

 granted, the new equation would not follow ; but I adhere to my 

 plan of mentioning only one point at a time. 

 I remain, Gentlemen, 



Yours sincerely, 

 Pembroke Colles;e, G, G. Stokes. 



Jan. 13, 185L 



XX. Mineralogical Notices. 



EPHESITE. BY DR. J. LAWRENCE SMITH. 

 [Silliman's American Journal, Jauuaiy 1851.] 

 HIS silicate is found with the emery of Gumuch-dagh, and 



T 



occurs on specimens of magnetic oxide of iron. It is of a 

 pearly-white colour, and lamellar in structure ; cleavage difficult. 

 It scratches glass easily, and has a specific gravity of from 3" 15 to 

 3"20. Heated before the blowpipe it becomes milk-white, but 

 does not fuse. At first sight it might be taken for white dis- 

 thene. It is decomposed with great difficulty by carbonate of 

 soda even with the addition of a little caustic soda. The alkalies 

 were separated by means of hydrofluoric acid. 



Silica 31-54 30-04 



Alumina 57-89 56-45 



Lime 1-89 2-11] 



Protoxide of iron . . 1-34 1-00^ 



Soda with a little potash ... 4-41 J 



Water 3-12 3-06 



This corresponds very nearly to the formula — 



2R0, Si03 + 5 (2A12 0^, SiO^) + 4H0. 



Atoms. Atomic weight. Per cent. Oxygen ratio. 



Soda . . '.<i'a^*' r 781-6 7-08 1 



Silica . . .-'6' 3400-2 30-77 9 



Alumina . . 10 6416-2 58-08 15 



Water ... 4 450-0 4-07 2 



This mineral has been designated Ephesite from its occurrence 

 at the emery locality near the ancient city of Ephesus. 



