CONTENTS. 
Arr. XXIV. Address of Sir David Brewster ‘Before the Twen 
tieth Meeting of the British Asapciion at ee Jay, 
31,1850, - 305 § 
XXV. On rs a Height of Lighting Rods by Prof. ra 
320° 
XXVI. On my "Blestrical Pecan of Coie Houses by 2 
Prof. Evias Loomis, — - a 
XXVII. On a-new method of decotiposing Silicates in sha pro- 
cess of Analysis; by Henry Wurtz, - - 823 5 
XXVUE On the availability of ihe Greensand of hee ate as te 
a source of Potash and its Compounds; by, Henry Wurtz, 926 _ 
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. Norton, . 330 
XXX. On the Analogy between the mede of hepichakn Woo 
Plants and the “ Alternation of Generations” observed in 
some Radiata; by James D. Dana, | 341 ‘a 
On Plectee mance as~a Moving Power by, Prof. a> = 
‘ E: 
= 
is: aa 
Bs ; 
Ss adinats size ‘ead length of, F 
; by Prof. Cuas. G. Pacr, M.D., - 349 
On Rutile and Chleniss in ee ; me Eee 0. “a 
. 302 
XXXV.. Sitesi on Emery; “y I es Sail 1D. 
- First part—On the Geology and peornicer of nai from 
park it 
XXXVI ‘On American Seoduseue 4 by Gro. I. Hide is ee 27 | 
| XXXVII. Optical Bay of several American Micas ; és . 
B. Sin LLIMAN, Jr., A.M., @.1).,"é&c. Fe e $72 | - 
ta 
XXXVI Analyses of Ele from St. Lawrence County, 
N.Y.; by Wu. J.C | 
Extracts from: the Premcediags of the Twentieth | 
ish Association, held at Edinburgh, July, 1850 
Oi tlantic —— their Mosnitnde, Malte eee 
386.—On talli lie Reflection, by Prof. G. G. 
of A ceteeteais hind 1 
