cone, the glittering of a flowing mudstream was unmistakable. Inasmuch as in Morgan's account of his visit the smaller cone is not mentioned, it is presumable that it has been formed since, by a lateral eruption; the old cone having, perhaps, reached the extreme limit of height to which mudlump force can raise its materials.

The steep slopes of both the old and new cone are suggestive as to the influence of sandiness on that feature, and the explanation of the steep inclination of strata, observed chiefly on Southwest Pass.

It is my impression that another cone exists in the marsh about two miles south of these. It is almost screened from view by the reeds, but the telescope shows it to be distinctly conical. It does not seem to have attracted notice heretofore.

But if mudlump cones are scarce in the marshes, the same is not true with reference to the salt and gas springs, which are reported to be quite abundant by the hunters-the only men whose occupation leads them to "thread the pathless waste" of reedy marsh, otherwise seldom visited, save by surveying parties, and alligators. These springs are found on or around all mudlumps, of whatever age; even on the shoals left behind by disintegrated lumps, where they issue under water, sometimes altering perceptibly the character of the water in the immediate neighborhood. The Southwest lighthouse was originally built on a mudlump separated from the mainland by a bayou; this is now filled up, but salt springs still issue at several points in the marsh near the foot of the tower. It is obvious that the gradual accumulation of deposit is not likely to check lively springs, possessing sufficient head to rise, hydrostatically, above the level of the alluvium; though in many cases they may lose themselves in the sandy strata.

I have not had an opportunity of ascertaining whether or not salt springs are known to exist in the marshes near the Forts, and above. I fully expect to find, however, that they do exist, though, for obvious reasons, they will become less and less abundant as we ascend the river. At New Orleans, as already stated, gas and salt water are reached, and brought to the sur face with considerable vehemence, by bores varying from 31 to 56 feet; and I have no difficulty in believing in the correctness of the impression made upon Col. Sidell, that the foundations of the New Orleans customhouse were located upon a mudlump. That such obstinate resistance as that of the "Head of the Passes" to denudation can hardly be attributed to a mass of river deposit, I have already intimated. A large mudlump mass has, probably, first caused the deflection.

* See above, p. 245.

[To be continued.]

Lyell's Principles of Geol., 10th ed., p. 552.

ART. LV.-On the existence of the (so-called) compound Ammonium Amalgams; by the late CHARLES M. WETHERILL, PH.D., M.D.

THE discoverer of methylamine did not succeed in forming a compound analogous to the ammonium amalgam, whether by the reaction of methyl ammonium chlorid with potassium amalgam, or by the influence of the galvanic current. This experiment, with negative results of Wurtz, is quoted in nearly all of the descriptions of the compound ammoniums.

In a series of experiments (this Journal, II, vol. xl, Sept., 1865) upon the formation and nature of the ammonium amalgam, by which it was demonstrated that this body is merely a metallic froth, I succeeded in forming the so-called amalgam of methyl ammonium. This body was found to be of a nature essentially similar to that of the ammonium amalgam, but of less turgescence. The salt used was the methyl ammonium oxalate, which was compared in this reaction with the ammonium oxalate. MM. Pfeil and Leffman (this Journal, II, vol. xlii, p. 72) repeated these experiments and confirmed the results, employing the tri-methyl ammonium chlorid. They also extended the reaction with sodium amalgam to the chlorohydrates of aniline, coniine, morphine and quinine and to the acetate of rosaniline; but without forming amalgams, hydrogen gas being evolved copiously without swelling.

H. Landolt (VI supplement, Annalen der Ch. u. Pharm., p. 346, "Ueber das ammonium amalgam ") states in a foot-note, that he had repeated the experiment with tri-methylamine chlorid and sodium amalgam, and found "that the turgescence of the mercury takes place only when the preparation contains ammonium chlorid; the pure compound gives no amalgam.

This rendered necessary a repetition of my experiment upon the compound ammonium amalgam, as I had not myself tested the salts employed with respect to their purity. The former experiments were performed with a pure methyl ammonium oxalate, for which I am indebted to the kindness of M. Carey Lea, Esq., who gave me some prepared by his new method, being the same described by him in this Journal, vol. xxxiii, p. 366.

In the present experiments I prepared a fresh portion of the methyl ammonium oxalate by Lea's process, viz: by the action of aqua ammonia upon methyl nitrate. The two liquids were placed aside in a stoppered bottle for ten days, by which time the ether had disappeared. The distillate of this liquid over caustic potassa was exactly neutralized by oxalic acid and evaporated to crystallization. After removing the ammonium.

oxalate, the mother water was evaporated to dryness and boiled with 95 per cent alcohol; the hot filtrate on cooling yielded nacreous scales of methyl ammonium oxalate. The mother water of these crystals, by concentration, furnished an additional quantity a little darker in color. By filtering the crystals and washing them with 95 per cent alcohol by the aid of the Bunsen filter pump, they were completely freed from the dark mother water in which they formed. As the quantity of salt at my disposal was not more than a gram, fearing to reduce it by a recrystallization, I first tested the effect of a solution of the crystals upon sodium amalgam, and then converted a portion of each cup to methyl ammonium oxalate in which the Pt was determined. All which remained of the oxalate was recrystallized from a hot solution of alcohol and ether and experimented with, as in the former case. The crystals appeared to the naked eye to be prisms, but the microscope demonstrated them to be feathery needles polarizing light. They were very electric when warm, and possessed the property of felting together when pressed by the finger. They yielded golden-yellow crystalline scales or plates when converted into the Pt salt This salt is much more soluble than the corresponding ammonium salt, and crystallizes again from its solution in golden yellow hexagonal and triangular scales, being part of the octahedron and its replacements. The following are the results of the different analyses, from which it may be perceived that the methyl ammonium oxalate is perfectly pure, and that, as stated by M. Carey Lea, the first crystallization of the oxalate is pure.

I noted with respect to the Pt salt that some crystallizations furnished scales of a reddish tinge, but which gave the same percentage of platinum as the golden-yellow scales. The small quantity of substance at disposal for the analysis required very careful weighing to of a milligram.

Analysis of methylam. chloroplatinates from methylam. oxalates.

These different specimens of methyl ammonium oxalate, dissolved in water, gave similar results when shaken with sodium

* Eq. Pt 1·98.

amalgam. To ascertain this fact, a portion of fluid sodium amalgam of the size of a pea was placed in a small test tube (inch diam.), and the solution of ammonium oxalate added, the swelling was observed both with and without shaking, in the cold and with warming. The same experiment was performed with the different specimens of methyl ammonium oxalate. The latter all swelled to from 8 to 10 times the original volume, which was very much less than the turgescence of the ammonium salt. With the compound ammonium salt, the swelling was not apparent until the tube was shaken and heat facilitated the reaction; this may be the reason that it has been hitherto overlooked. The methyl ammonium amalgam presented the same buttery appearance as the ammonium amalgam, and a knife blade placed in it was amalgamated. When the lump was pressed between two plates of glass, as in the method I proposed, to prove the frothy nature of the so-called ammonium amalgam, myriads of gas bubbles were apparent; when these were pressed out the amalgam was at once restored to the condition of mercury. In all cases shaking the tube appeared to be necessary in order to develop the swelling to its fullest extent. In performing this act, care was taken not to convey the ammonium salt to the methyl ammonium tube by the finger.

In the former experiments it was not deemed necessary to form the compound ammonium amalgam by the aid of the battery; in the present this result was attained in the following manner, (vide op. cit., Exp. 15).

A piece of filter paper was placed upon a glass plate, then saturated with a strong solution of the recrystallized methyl ammonium oxalate. A globule of mercury of the size of a small pea was placed upon the paper with the negative pole of 20 cells Bunsen in contact with it; the positive pole touching the paper. The globule swelled slightly, presented a buttery appearance, attached itself to and amalgamated the blade of a penknife which was in contact with the negative pole, and upon being pressed under a glass plate showed innumerable gas bubbles in its substance, (in fact was a metallic froth) which emitted an ammoniacal odor.

It results from these experiments that the compound ammonias (at least that which I have examined) may form the so-called amalgam. I defer the bearing which this fact has upon the socalled ammonium and hydrogenium amalgam to a paper of some experiments which will shortly be published.

SCIENTIFIC INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. On the spectrum of the Aurora Borealis.-ZÖLLNER has called attention to the fact already remarked by other observers that the lines in the spectrum of the aurora borealis do not coincide with those of any known element, and has endeavored to give a rational explanation of the want of coincidence without assuming the presence of unknown elements in the earth's atmosphere. If the lines in question are really of electrical nature and are produced by the ignition of highly rarefied gases, the ignition must take place at so low a temperature that it would be impossible to observe the lines in Geissler's tubes. Hence Zöllner thinks that the spectrum of the aurora does not correspond with any known spectrum of the atmospheric gases, because it is a spectrum of a different order which cannot at present be produced artificially. If, at a given temperature, A and E represent respectively the values of the absorptive and emissive powers for the wave length for the unit of thickness and density, m and σ the thickness and density of the luminous layer of gas, we have, according to Zöllner, for the brightness E of the part of the spectrum corresponding to 2, the η σ Ελ expression

E=[1 — (1 — A1) ]

Αλ

For a given gas and given temperature this expression depends only on the value of the product m σ. In a Geissler's tube filled with rarefied air, take the diameter of the narrow part of the tube as 1mm, and regard this as the unit of thickness m, and take as the unit of density the density of the enclosed air corresponding to a temperature of 0° and pressure of 1mm of mercury. If now we ignite the air in the tube by an inductorium, then at a constant temperature the spectrum would remain qualitatively and quantitatively unchanged if the diameter of the narrow tube were increased from 1 to 1000mm, and if at the same time the pressure on the gas were diminished to 1000

Wüllner found that in the case of nitrogen the spectrum became sufficiently luminous for spectroscopic examination only when the pressure was diminished to 46mm, while in the case of oxygen the necessary diminution was to 28 to 30mm. If we assume that in Wüllner's apparatus the current passing through a tube 1mm in thickness and under a pressure of 50mm produces light enough to observe the atmospheric spectrum, we may compare with this the thicknesses of the luminous layers which occur in the case of the aurora, which are of course far greater, and, at a distance from the zenith, to be estimated in miles. If we take the thickness of such a layer as only 1 kilometer, then at the same temperature as in the last case, the density would have to be only the one-millionth of that of the air enclosed in the tube, and therefore exert a pressure of only 0.00005mm at QC., in order that the