Pj-of. ConiieJ on the Voltaic Decompositio7i of Solutions. 353 

 axis in the same relation to it as that in which they an- 

 proachecl.t. From this we conclucle, that the space i-nund 

 the optic axis within the ring is traversed by only one 

 image, and therefore that there is only one sheet of the himi- 

 niterous surface in this place : the form of the two series of 

 cones also favours this view. This indicates what may not 

 inaptly be termed an eyelet-hole in one sheet, and a conical 

 point in the other. 



To determine the real nature of the refraction about the 

 optic axes ol biaxal crystals, will evidently require a o-ood 

 deal more of minute examination. 



If any fellow-labourers should enter on the subject, I should 

 be very glad to see their results in print, and am glad to be 

 able to inform them that Messrs. Watkins and Hill have un- 

 dertaken to fit up for sale crystals of arragonite, mounted in 

 a mode so as to facilitate the examination of the refraction 

 near tlie oplic axes. 



Queen's College, Cambridge, Feb. 1.3, 1841. 



}h ■ ^^^^"^^""'^ Decomposition of Aqueous and Alcoholic 

 Solutions. Bii Arthur CoNNEL, Esq., F.R.S.Ed., Pro- 

 fessor of Chemistry in the United College of St. Salvator's 

 afid St. Leonard's, St. A7idrei<a's. 



[Continued from p. 249, and concluded.] 

 II. Alcoholic Solutions. 

 J SHALL content myself with simply referring to the bk- 

 penments, by which I have shown that mider voltaic 

 agency water entering into the constitution of absolute al- 

 cohol IS resolved into its elements, hydrogen being given ofF 

 at the negative pole, and oxygen being "engaged in produ- 

 cing secondary effects on the hydrocai^onM" the aLhol, 



soh.finn 7 M "'•''"''''''"» ''^" extraordinary effect which the 

 o ution of the minutest quantities of alkalies, acids and saline 

 Docnes, have in promoting this action =i=. 



This fact, that the water of absolute alcohol suffers decom- 

 position urn er galvanic action, furnishes the key for solvin.. 

 all cases of the voltaic decomposition of alcoholic Solutions, bv 

 assimilating them to those which occur in aqueous solutions, 

 llie analogy between the two cases is complete, with the dif- 



.nXl'"r^'',l '"' ''\/''*^ ^«'"^-'- the appearances are less 

 n.aiked, horn the smaller quantity of water present, the in- 

 ferior conducting power of the solution, and the slight modi- 

 J'hil. Mag. 8. 3. Vol. IS. No. 118. Maij]Hn. 2 A 



