CONTENTS. Vii 
Pag 
- XXVIL On a new method of vate ae Silicates in the as 
_ eess of Analysis; by Henry Wurrz 323 
~ XXVIIL On the availability of the es of New derkan as 
oF a source of Potash and its Compounds; by Henry Wurtz, 326 ~ 
~ XXIX. On the Diurnal and Annual Variations in the Declination 
of the Magnetic Needle, and in the Horizontal and Vertical 
Magnetic Intensities ; by Prof. W. A. Norron, “+ 330 
XXX. On the Analogy between the mode of Reprodactibiy tin in 
Plants and the “ Alternation of Generations” observed in 
some Radiata; by James D. Dana, ., = - 341 
XXXI. On Becta: a see as a Moving. Power: by Prof. 
Cuas. G. Pace, <=, 4 
; XXXII. Singular asi ‘nd extraordinagh size Sena ioaih of 
the Secondary Spark ; by Prof. Caas. G. Pacz, M,D., - 349 
» XXXII. On Rutile and Chlorite in — : oy Professor 0. P. ; 
= Husgarp, M.D.,. - - 350 
s XXXIV, Oatllixedes. of Crystallized Oxyd of Cheocitnie in fur- | 
, . or the manufacture of Chromate of Potash ; a “4 
. P.- Braxn, 2°* 352 
. @ er Memoir on Emery ; + J. Evens Sicerie M. p= * 
“et First part—On 1 the Geology and Meeey of aA from Bee 
wee observatigns: made in Asia Minor, - 
. On American Spodumene ; by Gxoi J. Bevsn, - aA ea pa 
_ XXXVI Optical Examination of several : Ame Micas ; y. j 
B. Sittiman, Jr., A.M., M.D., &c.,_ - 372 
. >» XXXVIIL mes of ease from St Lawsenee Counts, 
a . Y.5 by W 383 
Fiteacts front the Piickediis of the Twentieth Meeting of the Brit. 
sh Association. tion, iation, held. at Edinburgh, July, 1850 :-— 
On Atlantic Waves: their Magnitude, Velocity, and Phenomena, by Dr. Scoressy, 
> 386.—On. Metallic Reflection, by Prof. G. G. Stoxes, 391.—On a Fictitious 
___. Displacement of Fringés of Interference ; by Prof. G. G. Sroxrs : On the Re- 
. stive Indices of several Substances, by the Rev . Prof. Powe, 392.—On the 
Hemisphere, by Mr. 'T. Hopkins, 397.—On the Argument for the Physical 
nection of Double = — from the Theory of Probabilities, by 
; —On Cometary Physics, by Prof. Sayru, 399.—On a new 
i rage Ps eitalline Lens, by Sir D. Brewster: On some Phe- 
