^SCIENTIFIC NEWS, - g|Q 



geognostlc appearances, in particular the structure of its 

 veins, and the nature of tlie interposed tabular masses, hav- 

 ing many of the characters of beds, yet appearing to be 

 either nearly horizontal veins, or lateral branches of com- 

 mon veins. The claystone of Arran, which was next de- 

 scribed, appeared to occur in overlying masses along with 

 the porphyry-slate, and also in veins along with pitchstone 

 and porphyry-slate. It would seem that wacke and basalt 

 are not very frequent or abundant rocks in Arran ; but when 

 they are observid, they present the usual appearances and 

 geognostic relations. 



From the observations in these two memoirs it appears, 

 that this island contains no transition rocks ; but is princi- 

 pally composed of primitive and floetz rocks. The allu- 

 vial rocks that occur in the valleys present the usual cha- 

 racters of the rocks of this class. 



Mr. Singer informs me, that he has prepared some novel 

 apparatus for the application of common electrical powers 

 to the purpose of chemical analysis, for the illustration of 

 his lectures on the chemical agencies of electricity, the first 

 •f which will be given on thursday, the 11th of april. His 

 galvanic battery exposes upward of 14000 square inches of 

 zinc surface. 



TO CORRESPONDENTS. 



Mr. Gowar's paper was too late for insertion in the pre- 

 sent number. 



ERRATUM. 



Page 197» line 22, for hypothesis ; for the, read hypo- 

 thesis. Farther, 



METEOROLOGICAL 



