treated with alcohol. semitransparent. Boiling water only divided it; but, on adding gradually weak sulphuric acid to a very slight excess, the clots disappeared, and it was filtered. 'What remained on the filter, when well washed and dried, consisted of 5.3 gram. [81-8 grs.] of sulphate of lead, containing 4 gram. [61-76 grs.] of oxide; which had been combined with 16 gram. [247 grs.] of the gum, that were reobtained by evaporating the liquor separated from the sulphate of lead. This gum, which retained an excess of acid, yielded neither malic nor phosphoric acid when treated with aleobol; which led me to suspect, that the lime contained in the gum of myrrh is saturated by acetic acid; and perhaps also by carbonic; for, if sulphuric acid be poured into a solution of this gum, a slight effervescence takes place, and a precipitate of sulphate of lime. We see from what precedes, that the gum of myrrh is not entirely separated from its solvent by the nitrate of lead; since of the 23 gram. [355 grs.] only 16 [247 grs.] fell down with the oxide. This must have been owing to the nitric acid set free; for a salt of lead surcharged with oxide, as the subacetate, precipitates almost wholly the solution of the gum of myrrh, and entirely, if a little alkali be added to the mixture. The part insoD. What remained on the filter (B.) was heated with alluble in water cohol, which dissolved all the resinous parts, and left behind a soft, transparent, substance, insoluble in boiling water, and weighing when dried 6 gram. [92.6 grs.]. It had all the properties of the gummy matter already mentioned. Resin pro duced. Its properties. E. The alcoholic solution (D.), mixed with the spirit used in washing the filters, yielded on evaporation 11.5 gram. [177-6 grs.] of a brown resin, with an aromatic bitter taste like that of myrrh. 1. This resin softens easily between the fingers, melts at 48° R. [140° F.], and does not become electric. 2. It emits an aromatic smoke while burning, and yields on distillation the same products as resins. 3. With potash it forms a kind of soap, the aqueous solution of which passes turbid through the filter. 4. On 5.5 gram. [85 grs.] of this resin of myrrh were poured poured 33 gram. [509.5 grs.] of nitric acid at 38°, which turned the resin blackish. The mixture being distilled emitted red vapours, but not very abundantly. After having obtained a product of about 20 gram. [309 grs.] from this solution, the retort was removed from the fire. A resiniform substance of an orange colour floated in it, which, when washed and dried was of a pale yellow, and weighed 1.5 gram. [23 grs.]. It was pulverulent, bitter, not very fusible, partly soluble in water, and formed with potash a saponaceous compound, which dissolved very easily in water, giving it a red colour, without any diminution of its transparency. This resiniform substance contains a great deal of carbon, and is sensibly altered by nitric acid, which only dissolves it. In other respects it comports itself like the resin of gamboge treated with nitric acid. The nitric solution, on which this substance floated, being evaporated to dryness, left a residuum, which being well washed, furnished 1 gram. [15:4 grs.] more of the resiniform substance, which had been kept dissolved by means of the nitric acid, Lime-water in excess added to the waters of elutriation separated 1.2 gram. [185 grs.] of oxalate of lime mingled with a small portion of malate. The supernatant liquid contained a bitter yellow matter. chiefly of a Sect. III. From these experiments it follows, that myrrh Myrrh consista consists principally of a gum different from the common gum. kind, the leading properties of which are racteristics. 1, To acquire a degree of cohesion from the action of Its chief chaheat, when its solutions are evaporated, which renders it partly insoluble in water: 2, To give out ammonia when distilled, and nitrogen gas when acted on by nitric acid; which gives it an affinity to animal substances: 3, To decompose solutions of lead, mercury, and tia, and unite with their oxides. Myrrh contains likewise about 0.23 of its weight of a very fasible bitter resinous matter. (To be continued.) SCIENTIFIC SCIENTIFIC NEWS. Royal Society of Edinburgh. Royal Society ON the 7th of January Sir George McKenzie continued of Edinburgh. his account of the Mineralogy of Iceland, and described' some very curious geological facts. Geological Society. On the 21st he concluded his mineralogical detail, with an interesting description of Mount Hecla and other volcanic districts. In this paper Sir George made some remarks which tended to place obsidian and pumice in a conspicuous point of view, as relating to the different theories of the Earth, and clearly proved their origin to be igneous, a position which has hitherto been denied by Werner and his pupils. On the 4th of February Dr. Brewster read an ingenious paper on the loss of the comet of 1770.-Sir George M'Kenzie described some remarkable hot springs in Iceland. To one of these he gave the name of the alternating Geyser, as it spouted from two distinct orifices evidently' connected within, but only from one at a time, the operations of which alternated with those of the other at regular intervals of time. On the 18th Professor Playfair read part of a Biographical Memoir of the late John Robison, LL.D. and Professor of Natural Philosophy in the University of Edinburgh. Mr. Allan communicated a letter from Dr. Henry, of Manchester, describing the position of some singular masses of a substance apparently composed of wax and resin, which had been laid bare by a late overflow of the river Mersey, a little below Stockport, about three feet under the soil, and supposed to be the refuse of some manufactory, of which no other vestige or recollection now remains. The First Volume of the Transactions of the Geological Society, in 4to, with many plates, is in the press, and will be ready for publication in the month of May next. ΤΟ TO CORRESPONDENTS. Philochemicus does not seem to be aware, that the object of the galvanie troughs he mentions was to get rid of the cement, all the disadvantages of which recur in the plan he proposes. Any danger to be apprehended from the use of earthenware or glass may readily be obviated by the simple and cheap defence of a case of common wood. With regard to the use of the word partiele, when he de fines it, in one place, the smallest portion of any compound substance into which it can be resolved without decomposition; and, in another, the smallest portion of any compound body, which we can procure by mechanical means; these two definitions are obviously not consistent with philosophical precision. The fact appears to be, that the word particle, or small part, a word with a certain laxity of signification in common use, cannot well therefore be confined to one precise and definite meaning on all occasions; but like many other terms, will have its exact sense to be determined in general by the context. L. O.C.'s paper will be inserted the earliest opportunity. As a request formerly made appears not to have been seen, or to have been overlooked, by some of my more recent correspondents, I beg leave to repeat it. It is, that they would leave in their manuscript a margin for the insertion of the side notes. It is also desirable, that, when a paper requires drawings for its illustration, none of it should be written on the back of the drawings. METEOROLOGICAL |