----, fossil, accompanying anthracite coal, ix, 165. ----, ----, at Mariner's Mill, Ohio, xxxi, 28.^f ----, ----, in coal strata of England, iii, 389; xxxiii, 87, 270. ----, ----, of the coal formations, _A. Brongniart_, iv, 266.^f ----, ----, analysis of _Ad. Brongniart's_ work on, vii, 178. ----, see farther under _Botany_ and _Vegetable_. Plaster, on the setting of, xvii, 371. ---- of Paris, see _Gypsum_. Plastic clay of the southeast of England, xxxiii, 92. ---- ---- and sand formation of New Jersey, Massachusetts coast, and elsewhere, vii, 34, 214, 244. Plate electrical machine, _R. Hare_, vii, 108^f; xxxii, 272.^f ---- ---- ----, viii, 378. Platinum, size of grains of, xvi, 389. ----, price of, (1833,) xxvi, 210. ----, imitation of, xxii, 383. ----, on the fusion of, _R. Hare_, ii, 295; xxxiii, 195; xxxv, 328; xxxviii, 155, 163. ----, test for, vi, 376. ----, amalgam of, xxvii, 363. ----, action of, on combustible gases mixed with oxygen, xii, 181. ---- mines, found in the Ural, Russia, xii, 384; xiv, 204; xviii, 190; xxviii, 395. ---- of Russia, large masses, xvi, 389; xlvi, 212. ----, large mass of, from Peru, iv, 28; xvi, 389. ----, analysis of the Russian, _J. J. Berzelius_, xviii, 162. ----, in France, xxvi, 389. ---- boilers, at Paris, xvii, 179. ---- lamp, xx, 385. ---- wire, ignited, i, 309. ---- ----, action of heated, on combustible gases, _W. Henry_, xii, 181. ----, spongy, combustion with, discovered by _J. W. Döbereiner_, vii, 387. ----, ----, _J. W. Döbereiner's_ researches on, xviii, 151. ----, ----, _J. Liebig_, xviii, 398. ----, ----, action of, prevented by certain gases, xxxi, 348. ----, ----, ----, _Kuhlmann_, xxxvii, 198. ----, on the dark precipitate of, _J. Liebig_, xviii, 398. ----, new compounds of, _J. W. Döbereiner_, xxviii, 130. ----, a bichloride of, combined with deutoxide of nitrogen, _H. D. Rogers_, xxxviii, 186; xxxix, 369. ----, a property of asbestus imbued with chloride of, xx, 160. ----, chloriodide of, _W. W. Mather_, xxvii, 258. ---- and hydrogen, no combination of, _J. W. Döbereiner_, xxxiv, 207. ---- and soda, a double sulphite of the protoxide of, _A. Litton_ and _Schnederman_, xliv, 274. ----, iodide of potassium and, _W. W. Mather_, xxvii, 257. Plesiosaurus, from north of Whitby, England, xxix, 364. ----, notice of, xvii, 289. _Plessy_, on the hydrosulphite of soda, xlix, 200. Pleurodon, _R. Owen_, xliv, 342. _Pliny_, on the influence of the ash on reptiles, xxx, 268. Plough, American, compared with French, vii, 190. Plumbagine, a new vegetable substance, xvii, 385. Plumbago formed by pressure, xlix, 227. ----, see _Graphite_. Plumbago floridana, v, 290. Plumbocalcite, new mineral species, xxvi, 386.