application of the effect of Neptune and the best possible modifications of the orbit of Uranus.

ART. XXIII.-Caricography; by Prof. DEWEY.

(Appendix, continued from vol. v, ii ser., p. 176.)

No. 234. Carex fusiformis, Chapman in literis.

Spicis distinctis; spica staminifera unica pedunculata erecta gracili, squamis oblongo-lanceolatis; pistilliferis binis vel ternis ovatis oblongis brevibus laxifloris, superioribus subapproximatis sessilibus, inferiore subremota pedunculata, tristigmaticis erectis; fructibus subinflatis inferne teretibus triquetris conoideo-rostratis longis brevi-bidentatis, squamam ovatam acutam duplo super

antibus.

Culm 6-10 inches high, triquetrous, smooth, slender, erect; leaves linear lanceolate, smooth, long as the culm; staminate spike single, erect, slender, pedunculate, near the upper pistillate ; pistillate spikes 2-3, ovate-oblong, few and loose-flowered, two upper nearly sessile and approximate, lowest subremote and pedunculate, with leafy bracts scarcely sheathing; stigmas three; fruit elliptic-triquetrous, tapering below, conic-rostrate above and slightly bidentate, smooth and a little inflated; pistillate scale ovate and acute, half as long as the fruit; plant pale green.

Floridas, Dr. Chapman; named in his letters as above, and is a distinct species.

235. C. Illinoensis, Dew.

Spica staminifera solitaria erecta cylindracea longo-pedunculata ebracteata; spicis pistilliferis ternis remotis folio-bracteatis, suprema ovata subsessili, inferioribus oblongis laxifloris exserte-pedunculatis erectis; fructibus tristigmaticis ovato-conicis ore integris nervosis subobtusis, in spicam supremam multo majoribus et longioribus aggregatis, squamam ovatam cuspidatam superne multo superantibus.

Culm 12-16 inches high, erect, slender, glabrous, scabrous on the edges, leafy towards the base, with long and leafy bracts; staminate spike single, erect, short, oblong, pedunculate, having oblong and obtusish scales brown on the edges; pistillate spikes three, remote, leafy-bracteate, the highest nearly sessile and ovate close-fruited, the two lower oblong, distant, loose-flowered and exsertly pedunculate; stigmas three; fruit ovate, conic, rather obtuse, entire at orifice, on the upper spike closer, larger, and much longer than the ovate and cuspidate scale, on the lower spikes loose and a little longer than the scale.

Augusta, Ill., Dr. S. B. Mead. Though related to C. conoidea, Schk., it is very different, and appears to be a new species. It is singular in the different size of the fruit on the same plant, being much larger and longer on the upper spike.

236. C. Georgiana, Dew.

Spica staminifera unica (plures?) pedunculata longo-cylindracea bracteata, squamis denis lanceolatis longo-setaceis; spicis pistilliferis ternis vel quaternis oblongis cylindraceis densi-floris foliaceobracteatis erectis, inferioribus longo-pedunculatis exsertis, superioribus subsessilibus; fructibus tristigmaticis ovatis conico-rostratis nervosis bidentatis, squama lanceolata scabro-aristata brevioribus. Culm 20 inches or more high, triquetrous, with long leafy bracts surpassing the culm; staminate spike slender, long, with long and slender bristly scales; pistillate spikes 3-4, erect, cylindric, 1-2 inches long, the two lower long pedunculate and exsert, the upper sessile, all long leafy bracteate; stigmas three; fruit ovate, conic-lanceolate, scabro-rostrate, round-triquetrous, short two toothed, sometimes teeth a little elongated; scale lanceolate, awnlike, scabrous, longer than the fruit.

Georgia, Dr. Cooley. I referred to this locality under C. mirata, but, as my friend John Carey, Esq. suggests, the plant differs too much from that species. The fruit of C. mirata is long and wide bifurcate, while this is short two-toothed; the scale of the former equals the fruit, while this surpasses the fruit. On C. mirata too the fruit is longer and more slender than on this. The fertile spikes on both are large, but are far less than on C. gigantea, Rudge and Muh.

SECOND SERIES, Vol. VI, No. 17.-Sept., 1848.

32

ART. XXIV.-On Gutta Percha; by EDWARD N. Kent.

GUTTA Percha is soluble in pure chloroform, bi-sulphuret of carbon, rectified oils of turpentine, resin, gutta percha and tar, and also in terebene, hydrochlorate of terebene, and slightly in pure ether. Of these solvents the first two are the best, and dissolve the gutta percha at low temperatures. The other solvents act only at a temperature above 70° F., and when the solutions are cooled much below 60°, the gutta percha is deposited in a voluminous granular mass. The length of time required for the production of this precipitate, depends upon the degree of cold; sometimes it requires several days, and at other times the exposure of an hour suffices to produce it. By warming this mixture, the precipitate is readily redissolved, and by exposure to cold is again precipitated at will.

Solutions of gutta percha are naturally of a reddish brown color, and do not become colorless by standing at rest for several months in a warm situation. If the solution is made sufficiently dilute, which is the case when one part of the gum is used to sixteen parts of the solvent, it can be filtered slowly through paper or muslin, and is then colorless.

Solutions of gutta percha are precipitated by alcohol, and when chloroform or bi-sulphuret of carbon are used as the solvent, the gum is recovered in its natural state either by evaporation or precipitation; but when any of the hydro-carbons are used for a solvent, a portion is retained with such tenacity that it cannot be removed without decomposition of the gum.

A solution in chloroform, filtered, and precipitated with alcohol, leaves the gutta percha when dry, of its natural strength, translucent, colorless, and pure.

When two or three parts of washed ether are mixed with a filtered solution of gutta percha in chloroform, and the mixture left for a short time at a temperature below 60° F., it precipitates in a perfectly white powder, which when washed with alcohol, filtered and dried, leaves the gutta percha in a pure white, opaque, voluminous mass, very soft and delicate to the touch, not unlike the pith of a young tree.

If a small quantity of the above mixture (before precipitation) is poured upon a glass plate and allowed to evaporate spontaneously, a thin opaque film of pure white gutta percha remains, which has the appearance and delicate feeling of the finest white glove leather. By a gentle warmth it loses its opacity and beautiful appearance, and becomes transparent or translucent, according to the thickness of the film. The state of aggregation which causes the opacity and delicate feeling of gutta percha prepared in the above manner, is owing to the precipitation of the gum, caused by the cold produced in the rapid evaporation of the ether.

The small portion of gutta percha, insoluble in any of the above solvents, consists of a red coloring matter, woody fibre, and earthy bases. The coloring matter is soluble in water, and precipitates on the addition of alcohol.

Crude gutta percha contains a small portion of a soft yellow resin, soluble in alcohol, ether and turpentine. This resin is separated by precipitating a solution of gutta percha with alcohol and evaporating the solution.

By destructive distillation, gutta percha yields an oil similar to that obtained from caoutchouc. The crude oil is dark brown by reflected, and red by transmitted light. It is limpid, grows darker by exposure to light, has a very disagreeable smell, is not spontaneously volatile, is but slowly soluble in 90 per cent. alcohol, and has a specific gravity of 856. By two rectifications a light yellow oil is obtained, volatile below 320° F., which constitutes about one-half the measure of the crude oil. This product is spontaneously volatile, dissolves readily in alcohol, and grows darker by exposure to the light.

The most remarkable property of gutta percha, that of its becoming soft and plastic by heat, and returning to its natural state when cold, has already been taken advantage of in the arts, and several patents have been granted to Mr. Hancock in Europe for valuable processes of working the material into a great variety of articles, for which it appears to be admirably adapted. In this country but little has been done with it, except for the manufacture of bands for machinery, and soles for boots; but it will doubtless be soon brought into extensive use, in a great number of our domestic manufactures.

The interesting electrical property of gutta percha, first noticed by Faraday, is truly wonderful. A piece of the manufactured thin sheet gum, cannot be taken from a paper in which it has been wrapped, without exhibiting this remarkable property, and by gentle friction with a silk handkerchief, a spark is readily obtained from it of an inch in length.

From the excellent non-conducting power of gutta percha, it is likely to come into extensive use in the manufacture of electrical apparatus, and it has already been employed to some extent for insulating the wires of Morse's electro-magnetic telegraph. New York, Aug. 1st, 1848.

ART. XXV.-On Emerald Nickel from Texas, Lancaster County, Pa.; by Prof. B. SILLIMAN, Jr.

THIS is the same mineral which I have before described under the name of "hydrate of nickel."* The name now proposed is in accordance with the custom of giving a trivial name to mineralogical species, and has been suggested by my friend, Prof. C. U. Shepard, as peculiarly appropriate from the brilliant color and transparency of the mineral, resembling the emerald. The existence of carbonic acid in this mineral as an essential constituent, was overlooked by me from the fact that it is all expelled at redness, and was therefore in my analysis put down as water. The water given off in the close tube does not change litmus paper, and the mineral does not effervesce in dilute cold hydrochloric acid. My attention was first directed to the probable existence of carbonic acid in this mineral, by a notice from Dr. D. R. Thomson,† describing as a new mineral a carbonate of nickel from the United States, coating specimens of chromic iron. Prof. Shepard also mentioned to me that he had found carbonic acid in the Texas nickel mineral first described by me. I have therefore made a new analysis of the mineral in question, selecting the finest and most transparent colored specimens in my power.

The following mineralogical description is mainly the same which I have before given, save that having much better specimens on which to determine the specific gravity, that now given may be regarded as more correct than the former determination.

Emerald Nickel.

Massive, stalactitic, occurring in thin crusts on chromic iron. Hardness 3-3-25, being but little above calc spar.

=

=

Gravity 2.570-2-693, two trials on different portions. Lustre vitreous, brilliant. Color emerald-green. Transparent. Streak delicate pea-green. Very brittle. Its pyrognostic characters have already been so fully described in the article first quoted, that it is useless to repeat them here; they differ in no respect from those of pure artificial hydrate of nickel.

The water of this mineral is partially expelled at the ordinary temperature of a water bath (212° F.); this fact led to estimating the total volatile product of the mineral too low, in the former description of this species. Carefully dried over sulphuric acid, the mineral lost on two trials 41-370 and 41.008; mean = 41.189 per cent.

The carbonic acid was estimated in the apparatus described by Fresenius and Will for analyzing carbonates.

* This Journal,

ii

ser., vol. iii, p. 407.

↑ Phil. Mag., Dec., 1847, p. 541.