I. How does carbonate of magnesia act upon sulphate of lime in the presence of free carbonic acid?-To test the degree of this action, I adopted the following course. I mixed in a suitable vessel ten grams of well washed carbonate of magnesia, twentyfive grams of sulphate of lime, (gypsum,) and five hundred cubic centimeters of distilled water; which mixture I afterwards treated for a short time each day during four weeks, with well washed carbonic acid gas, so as to secure a constant supply of bicarbonate of magnesia to the solution of gypsum. The solution thence resulting, after being separated by filtration from the white residue, was equal to four hundred and fifty cubic centimeters. I placed it in a flat glass dish, and left it to gradual evaporation at the ordinary temperature.

After a few days rest the bottom of the vessel began to be covered with a small amount of sediment. No further noteworthy change took place, until the whole liquid gradually formed into a solid crystalline mass, consisting in the main of a net-work of needles. The solution, being tested before its solidification, was of a slightly alkaline reaction; the crystals resulting from its evaporation were transparent, yet crumbled readily to a white powder when exposed to dry air.

One hundred parts of an apparently air-dried sample of the saline mass, contained

One hundred parts of the same mass, heated to a dull red heat, lost 51.0593 parts of its weight; leaving therefore 48.9407 parts of a white residue.

These analytical results, if considered in connection with the general properties of the original liquid as above stated, and the consequent solid crystalline residue, tend to prove that the solid matter may, with some propriety, be considered as consisting of

Carbonate of lime,

Basic hydrated carbonate of magnesia

3(MgO, CO2)+(MgO, HO),

1.4268

2.4911

Sulphate of magnesia (MgO, SO3+7HO), 96·8020

As the whole amount of the saline compound obtained in the experiment just described, was 22-605 grams, we learn that about 14.5 grams of gypsum had been decomposed, while some of the carbonate of lime (or more properly, bi-carbonate) left in the originally diluted liquid, had been separated during the progress of its concentration as carbonate of lime. The apparently slow decomposition of gypsum must be attributed to the limited solubility of that compound. It is not unreasonable

to presume that carbonic acid, under pressure and at common temperature, would alter the degree of action above illustrated.

II. How does carbonate of magnesia act upon sulphate of lime in the presence of free carbonic acid and chlorid of sodium?-In this investigation I proceeded thus: I weighed into a glass bottle 31 parts of commercial carbonate of magnesia, 86 parts of gypsum, 58 parts of chlorid of sodium, and 3000 parts of distilled water, and treated the whole mass with carbonic acid gas for several weeks, as described in a former experiment. The filtrate, separated from the undissolved white mass, which mainly consisted of gypsum and carbonate of lime, besides mere traces of carbonate of magnesia, was evaporated to dryness at 180° F., and the residue subsequently extracted with absolute alcohol. The alcoholic extract contained (beside a very small quantity of chlorid of sodium), 0.4370 grams of chlorid of magnesium, while the residue left after the extraction by alcohol contained 0.0570 grams of oxyd of calcium, 0-2243 grams oxyd of magnesium, and 0.6860 grams of sulphuric acid. This proved the presence of 0.6532 grams sulphate of soda, 0·4773 grams sulphate of magnesia, beside 0-1018 grams carbonate of lime, and 0.1236 grams carbonate of magnesia, with part of the chlorid of sodium unchanged. These results indicate,

1. That gypsum, carbonate of magnesia, and carbonic acid in the presence of chlorid of sodium, form chlorid of magnesium, sulphate of soda, and carbonate of lime.

2. That at a certain higher temperature, the sulphate of soda and chlorid of magnesium partly re-transform into sulphate of magnesia and chlorid of sodium.

3. That the solubility of the gypsum governs the degree of decomposition.

(To be continued.)

ART. XXXII.-A new Meteoric Iron, "the Colorado meteorite," from Russel Gulch, Gilpin Co., near Central City, Colorado Territory; by J. LAWRENCE SMITH, Prof. Chem. in University of Louisville.

I HAVE known of the existence of a new meteoric iron from Russel Gulch in Colorado, for about two years, but it was only recently that it passed into my hands. I first heard of it in the possession of Mr. Fisher of New York, who subsequently turned it over to Prof. C. F. Chandler of Columbia College, New York, who kindly submitted it to me, as I am furnished with the necessary means for cutting up and scrutinizing thoroughly this class of bodies.

The mass of iron is accompanied with the following label: · "Meteoric iron found in Russel Gulch, Feb. 18, 1863, by Mr. Otho Curtice. Weight 29 lbs. Brought to New York, Feb. 1864."

The mass measures in its extreme length, breadth, and thickness, 8×7×5 inches. It is perfect in all parts except at one extremity, and, as stated above, weighs 29 lbs.

This iron is one of medium hardness, with the density 7.72, and when cut through was found to contain a few small nodules of iron pyrites. It is attacked readily by nitric acid, and gives bold Widmannstättian figures without very sharp angles. It resists the action of the air and moisture very well, and is consequently but little altered on the surface. No siliceous minerals could be traced in any of the crevices. On analysis its composition was found to be

I have not made any further observations in relation to the presence of copper in meteoric iron since 1852, when I called attention to it. Since then I have become more confirmed in the opinion, then first expressed, that copper would be found in all meteoric irons; this has been the result of examinations of many well known meteoric irons, and all new ones that have come under my examination.

One or two grains of the iron is all that is necessary for the examination, if it be done carefully; but four to five grains had better be used. Dissolve the iron in chlorhydric acid, and if necessary add a little nitric acid; it is as well at all times to add a drop or two at the end of the operation. Evaporate away the excess of acid, add water, precipitate with sulphuretted bydrogen until there be an excess of gas in the solution; throw on a filter and wash with water containing a little HS, dry the filter, burn in a porcelain crucible, treat the residue with a little nitromuriatic acid, and evaporate to dryness, with the addition of a drop or two of sulphuric acid; treat the residue with water, when the introduction of a clean plate of iron will cause a deposition of the copper with all its characteristic properties.

ART. XXXIII.—On Gay-Lussite from Nevada Territory; by B. SILLIMAN.

IN September, 1864, I visited the body of saline water known as Little Salt Lake, situated near Ragtown, about a mile and a half south of the main emigrant road to Humboldt. It fills the bottom of a deep funnel-shaped depression in the Desert plain. The form and other peculiarities of this depression suggest a volcanic origin. It is distinctly crater-shaped, with the outline a double ellipse, made apparently by the coalesence of two craters; the larger is to the north, and has a diameter of about a mile and a half. The whole length north and south is somewhat greater than that from east to west in the larger division. The water-surface is about 200 feet below the lip of the crater, which is elevated somewhat above the general level of the plain. The slope of the converging sides is steep, varying from 25° to 45°; the approach to the water is therefore difficult, except at one or two points where an oblique footpath has been worn. There is a narrow margin or beach, varying from a few yards to a hundred feet or so, covered with shoal water, and the shore then plunges off to very deep water. There is a small island in the northern or larger division of this lake, also surrounded by shoal water. The section of the slope shows a series of beds of volcanic materials, lapilli and ashes, mixed with boulders or masses of black basalt, and concretions from thermal springs. The shores on the west side are also skirted with calcareous matter, and there is a steady flow of water from numerous small springs of fresh water into the lake. One of these springs is a copious fountain of excellent drinking water. The water of the lake is very saline. Its taste is salt, bitter, and decidedly alkaline. Its effect on the skin in bathing is that of a solution of an alkaline carbonate, and its odor is strongly marine. The rocks are encrusted with saline matters resulting from the evaporation of the waters.

The surface of the lake swarmed with small ducks; and divers sandpipers, cranes and other aquatic birds were on its shores. Myriads of larvæ of a species of fly (equally abundant at Mono lake) swarm in the shallow waters of the shore, but no fish appear to live in it. The water is so dense that a swimmer floats on it like a cork. There are no thermal springs now active in the lake, the temperature of which is normal.

Gay-Lussite.-A large stick floating on the shore and covered completely with an incrustation of yellowish-white crystals tubular in form attracted my attention. A careful search along the shores failed to detect others of a like kind adhering to the rocks, and it occurred to me that probably the waters being diluted

near the shore were not dense enough to deposit these crystals; and that if we could reach the island we might find them there, where, from the absence of fresh water springs, the saline solution of the lake would be more dense. This conjecture was fully verified. Mr. Semple, my secretary, succeeded in reaching the island in a very insecure boat, where he found the shores completely incrusted with beautiful clusters of these crystals, whose acute edges cut the naked feet. We secured an abundant supply of this rare and interesting mineral which, I believe, had not before been recognized in the United States. No other crystallized mineral was discovered.

The Gay-Lussite obviously has its origin from the reaction of the salts of soda and lime with which the waters are abundantly charged, and being very slightly soluble is readily deposited in these situations where the density of the water is maintained or increased by solar evaporation.' Hence it does not occur along the shores where the marginal springs of fresh water dilute the solution. The flow of these springs does not in summer fully replace the solar evaporation, as is evident from the water-line retiring slightly from its winter level.

This interesting lake has no outlet. It has plainly been a point of volcanic activity in modern geologic times, its eruptions being confined to mud, ashes, pumice and lapilli. It is one of a considerable number of similar phenomena with which the Great Basin is dotted, and of which Mono lake, on the western margin of the Desert, is the most remarkable. The bottom of the ancient lake whose waters have left beautiful terrace-lines along the sides of the Humboldt and other mountain ranges, when these were either marginal shores or islands of this great mediterranean sea of fresh or brackish waters, is every where strewn with dead fresh-water modern shells, chiefly univalves.

ART. XXXIV.-On crystals of Gay-Lussite, from Nevada Territory; by JOHN M. BLAKE.

THE crystals of Gay-Lussite here described were obtained by Prof. B. Silliman in 1864, at Little Salt Lake, near Ragtown, Churchill Co., Nevada. The crystals differ strikingly from those measured and described by Phillips (Phil. Mag., April, 1827) in the proportional development of the planes as is shown by comparison with the figures given by Phillips, and by Descloizeaux (Ann. Ch. Phys., 3d series, vol. vii, p. 489).

1 Gay-Lussite has been made artificially by J. Fritzsche, by mixing eight parts by measure of a saturated solution of carbonate of soda with one of a solution of chlorid of calcium of 1∙130-1∙150 specific gravity.-J. f. pr. Ch., xciii, 339. AM. JOUR. SCI.-SECOND SERIES, VOL. XLII, No. 125.-SEPT., 1866.