_Porter, T. D._, contributions to the Geological Society, ii, 143. ----, geological notice of some parts of North and South Carolina, iii, 227. ----, reply to _T. Cooper_ on tests of arsenic, iv, 160. ----, mineral localities on the Connecticut, ix, 177.^f ----, specimens of Zircon, iii, 229; v, 271. _Porter, W. S._, sketches of Alabama, xiii, 77. Portugal, public instruction in, vii, 198. Post office department, progress of the American, xv, 373. Post offices in France, income of, for 1824, x, 174. Postage of printed sheets in England, xlix, 228. Pot and pearl ashes, method of manufacturing, by _G. A. Rogers_, viii, 304. Potamogeton Claytoni, xlv, 38. ---- pulcher, xlv, 38. Potassa in sea-water, iii, 371. ----, caustic, of commerce, xxxv, 299. ----, commercial, of New York, researches on, _L. C. Beck_, xxix, 260. ----, ----, adulteration of, xxix, 261. ----, ----, manufacture of, xxix, 261. ----, mode of obtaining from feldspar, _Fuchs_, xxi, 157. ----, detection of, by the oxide of nickel, xvi, 387. ----, mode of separating from soda, xxix, 273. ----, Davy's original mode of decomposing, xxi, 367.^f ----, action of, on organic matters, xvii, 382; xxiv, 372. ----, action of, on cholesterine, xliv, 60. ---- and soda, mixture of pure carbonates of, xlix, 195. ----, carbonate of, mode of preparing, free from silica, xlix, 195. ----, chlorate of, mode of obtaining, ix, 201. ----, pure chromate of, xx, 409. ----, to test the chromate of, _S. Zuber_, xxiv, 372. ----, chromate of, means of determining the purity of, xvi, 392. ----, ----, a test for distinguishing strontia and baryta, xxxvi, 183. ----, bichromate of, ulcers produced by the use of, xvi, 384. ----, manganesiate of, _F. Wöhler_, xxviii, 137. ---- and copper, sulphate of, xx, 195. ---- and silica, new compound of, xvi, 397. Potassium, atomic weight of, xlvii, 189. ----, preparation of, viii, 372. ----, best method of preparing and preserving, xix, 205.^f ----, new apparatus for obtaining, _L. D. Gale_, xxi, 60.^f ----, improvement in Brunner's process for, _R. Hare_, xxiv, 312. ----, an improved mode of obtaining, _R. Hare_, xxxviii, 338; xl, 27. ----, properties of, xvii, 182. ----, price of, in 1825, ix, 387. ----, experiments on, by _J. T. Ducatel_, xxv, 90. ----, ammoniacal nitruret of, xxv, 205. ----, iodide of platinum and, _W. W. Mather_, xxvii, 257. ----, preparation of iodide of, ix, 188. ----, ferridcyanide, deoxidation of, _C. F. Schönbein_, xlix, 203. ---- and naphtha, explosive compound produced from, xxiv, 315. ----, mode of filling tubes with, xxiv, 316.