PRE 
Powder of Balda, viii, 204. 
mills, inflamed by the stroke 
of copper, xili, 161. 
Powders, fulminating, see Fulmin- 
ating. 
Powell, B., on the interference of 
light, xxxviti, 107. 
——-, on refractive indices, xxxvill, 
107. 
, on the wave theory, xxxviil, 
108. 
, on radiant heat, xl, 313. 
, on certain cases of elliptically 
polarized light, xliv, 171. - 
, on the elliptic polarization of 
light, reflected from various sub- 
stances, xlvi, 390. 
Power of horses, xxi, 167. 
Pozzuolana, iv, 378. 
Practical Tourist, review of, xxiii, 
213. 
Prague, statistics of, ix, 184. 
Prairies, origin of, R. W. Wells, 
1, 331. 
, —— and extension of, R. 
Nutt, xxiii, 40. 
of the West, C. Atwater, i, 
116. 
and barrens of the West, A. 
Bourne, ii, 30. 
of Alabama, W. W. McGuire, 
xxiv, 187; xxvi, 93. 
formation of Opelousas and 
Attakapas, W. M. Carpenter, 
Xxxv, 344. 
, observations on, G. Jones, 
xxxill, 226 ;—dry prairies, 226 ; 
comparison with Holland, 228. 
of Ohio, xxxili, 230. 
of Texas, J. L. Riddell, 
Xxxvil, 212. 
, Hoo-wallow, of Texas, no- 
tice of; xxxix, 211. 
Prase in Massachusetts, i, 344. 
in Rhode Island, viii, 226, 230. 
in Pennsylvania, viii, 238. 
Precession of the equinoxes, re- 
marks on, vil, 323!; viii, 132, 
139. 
s 
, constant of, O. Struve, 
xlvii, 91. 
207 
PRE 
Precipitate, purple, of silver and 
gold, xxil, 198. 
Prehnite, L. P. Walmstedt on, ix, 
378. 
, datholite, &c. at Kewenaw 
Point, Lake Superior, C. T. Jack- 
son, xlix, 87. 
, in Connecticut, 1, 50, 185; 
ii, 232; vi, 223. 
, 1n Massachusetts, 1, 114; 111, 
364. 
, in New Jersey, ii, 188, 191, 
195, 197; v.!239)s"'xl,-69);- xliv, 
58. 
, in Pennsylvania, x, 220. 
Premiums by the French Academy 
of Sciences, for 1827, xiv, 380, 
389. 
19-4. 
offered by the Society for the 
Encouragement of National In- 
dustry, France, 1821, 1822, iv, 
192: 
, for 1881, xxii, 
, for 1882-34, xxil, 
359. 
, for Mechanical Arts, iv, 192. 
, for Chemical Arts, iv, 192. 
, for fabrication of Russian 
leather, iv, 193. 
—-, for Economical Arts, iv, 
193. 
, for useful inventions in agri- 
culture, xvill, 382. 
, for chemical and medical dis- 
coveries, xxil, 194. 
, scientific, xxiv, 210. 
, see farther under’ Medals 
and Prizes. 
Prenanthes aphylla, v, 299. 
Preservation of objects in Natural 
History, iv, 198. 
of specimens of animals, di- 
rections for, xii, 271; xix, 52. 
ibid, with arsenical soap, 
xix, 53. 
of zoological collections from 
insects, 7. S. Trail, xv, 167. 
of animal and vegetable sub- 
stances from insects, J. Ma- 
cartney, Xxxi, 867. 
