one of the minerals of this state, although as early as 1865 Prof. E. A. Strong collected from the gypsum beds of Grand Rapids a quart, or more, of platy particles, which he forwarded to Dr. Alexander Winchell, previously State Geologist.

The present locality is in the northern part of the county, upon the line of the Lake Shore and Michigan Southern R.R., one mile west of the village of Scofield. Here a quarry was opened some three years ago by the Michigan Stone & Supply Co., of Detroit, the rock being crushed and used mostly for macadamizing purposes. The bed rock is overlain with from four to seven feet of soil and blue bowlder clay and its surface is scratched and grooved by glacial action. Channels and large "sink-holes" have been dissolved out by the water from the surface. The upper four feet of this bed is a grayish impure limestone, considerably "jointed," made up of fine, closely compacted layers, frequently contorted and banded with carbonaceous matter. It contains, in places, great numbers of small, obscurely defined fossils. This passes into a compact dolomitic limestone, from seven to eight feet in thickness, beneath which lies the so-called "sulphur-bed." This is a stratum of yellowish-brown impure limestone, varying in thickness from one to three feet and having but little dip. It contains brachiopods, corals and bryozoa and considerable carbonaceous material, here and there giving a strong oily odor. Wherever exposed to view it is seen to be cavernous in structure, the pockets varying in size from a fraction of an inch up. to three feet. The larger ones are flattened and lie with their longer axes parallel to the plane of the bed, as though dissolved out by water flowing along the bed, rather than from above. Just beneath this "sulphur bed," and quite sharply separated from it, is a seam of bluish-gray, gritty, siliceous lime-rock, varying in thickness from one to three feet. This is curiously streaked with flexuous, but approximately vertical channels, lined with brownish, carbonaceous material, suggestive of the remains of fucoid stems. Under the magnifier the entire rock is seen to be finely porous and to consist of sand grains embedded in the calcareous paste. Passing downward, the rock becomes more of the nature of a sandstone and is said to become softer. The "sulphur bed" is thus seen to lie from sixteen to eighteen feet below the surface between a compact, dolomitic limestone and a calcareous sand rock. The pockets in the bed, above described, are lined with scalenohedrons of calcite, or tabular crystals of celestite, or both together. In some places the latter mineral becomes a chocolate brown. The sulphur generally occurs in bright lustrous masses towards the center of the cavity, intermatted frequently with the above minerals. Fragments as large as one's fist are

readily removed. Some of the smaller cavities contain nothing but sulphur and one was found filled with selenite crystals. About an acre of this bed had been removed when the locality was visited and from this the superintendent estimated that one hundred barrels of pure sulphur had been obtained.

It becomes a matter of interest to speculate upon the source of the mineral, since sulphur is so commonly associated with volcanic phenomena. At Grand Rapids it has, without doubt, resulted from the decomposition of the calcium sulphate, but no deposits of gypsum are known in this part of the state. That it was brought to the place of deposition in some form by water, along with the celestite and calcite, admits of no doubt. Although the overlying limestone contains a few cavities, but few of them contain any of the sulphur, and these are situated very near the sulphur bed. The underlying rock is still more free from the mineral, so it seems that the water must have been introduced from the side. At one end a stream of water was found entering the quarry at the level of this bed, highly charged with hydrogen sulphide and depositing a considerable quantity of the white precipitate of sulphur over the rocks and weeds. Some distance from where the water enters, this precipitate begins to assume a slightly yellow tinge, and upon breaking open the larger masses a nucleus of crystalline sulphur may occasionally be detected. Similar masses were found in some of the cavities, the outer portion having a lightish-yellow, mealy appearance, while the interior is solidly crystalline. The well water of the entire region is said to be charged with this same gas and it seems highly probable that the sulphur has resulted from its decomposition. Not unfrequently masses of the sulphur are found, however, of which the outer surface is vesicular, as though corroded by some solvent. Still, not believing that the hydrogen sulphide has been or could be formed directly from the action of the water upon the native mineral, it remains to consider its source. In many instances this gas is formed from the decomposition of iron pyrite, or marcasite, in the rocks, the iron being converted into an oxide and the sulphur obtaining its hydrogen from the water. No trace of these minerals, however, was detected in any of the rocks, although it is possible that they may occur in sufficient quantities farther back. The presence of so much carbonaceous matter in the bed itself, as well as in the rock above and below, indicated by the color and odor, leads me to strongly suspect that the gas has resulted from the decay of organic remains, animal or vegetable, or both.

Ypsilanti, Mich., July 12th, 1895.

ART. XXVI.-On the Double Salts of Caesium Chloride with Chromium Trichloride and with Uranyl Chloride; by H. L. WELLS and B. B. BOLTWOOD.

NEUMANN has made an extensive investigation of the double salts formed with chromium trichloride and the chlorides of several other metals, not, however, including cæsium. He obtained a violet double salt in each case with ammonium, potassium, rubidium, beryllium and magnesium, corresponding to the general formula, 2M' Cl. CrCl,. H,O, while with lithium, sodium, calcium, strontium, barium, zinc and cadmium he was unable to prepare any double compounds. The double fluorides, 2NH F. CrF,. H,O, and 2KF. CrF,. H,O, which are analogous to Neumann's salts, have been mentioned by Wagner, who also prepared the compounds 4NaF. 2CrF ̧. H2O and 3NH,F. CrF,. The existence of the latter salt has been confirmed by Petersen.‡

Since Neumann had not prepared any cæsium-chromium chloride, and because, from the well-known comparative insolubility of cæsium double salts, it seemed possible that a greater variety of compounds would be obtained with this than with other metals, we have undertaken an investigation in this direction. As the result of a systematic search, however, we have added only a variation in water of crystallization to Neumann's general formula.

Two salts have been obtained. One of these, 2CsCl. CrCl,. H,O, is violet in color, corresponding exactly to Neumann's compounds, while the other, 2CsCl. CrCl, . 4H,O, is green. The violet salt was prepared by saturating warm aqueous solutions containing various proportions of the two simple chlorides with gaseous hydrochloric acid. The green salt was obtained from cold solutions by the use of hydrochloric acid, and without its use by evaporation over sulphuric acid.

The salt 2CsCl. CrCl,. H,O forms aggregates of very minute crystals of a magnificent red-violet color. It is stable in the air and does not lose its water at 160°. It is very slowly soluble in cold water, forming a green solution from which the green salt is deposited upon evaporation at ordinary temperatures. The four crops analyzed were prepared with amounts of cæsium chloride and chromic chloride varying from 15 g. of the first and 50 g. of the second to 50 g. of the first and 10 g. of the second. Gaseous hydrochloric acid caused a deposition of the salt from warm solutions. The products, after careful *Liebig's Annalen, ccxliv, 329. Berichte, xix, 896.

J. pr. Ch., II, lx, 52.

drying with paper and over sulphuric acid, gave the following results upon analysis:

The salt 2CsCl. CrCl,. 4H,O is deposited from cold concentrated solutions in the form of green, apparently monoclinic crystals. It is somewhat deliquescent, very soluble in water and loses no water in the desiccator over sulphuric acid. At 110° it readily loses three molecules of water and is converted into the violet salt. Three crops analyzed were prepared as follows: Crop A, by evaporating a solution of 50 g. cæsium chloride and 25 g. of chromic chloride; Crop B, by dissolving the violet salt in water and evaporating over sulphuric acid; Crop C, by cooling a concentrated solution of 50 g. of each chloride with the aid of ice and saturating it with hydrochloric acid. The results were as follows:

A determination was also made of the water lost at 110°:

Water..

Found.
9.90

Calculated for 3H2O in 2CsCl. CrCl,. 4H,0. 9.51

The variation in color of the two salts that have just been. described is interesting in connection with the violet and green modifications of chromic salts in general, which have furnished the ground for much investigation and discussion. In the case under consideration the transformation from one color to the other is accomplished by the addition or subtraction of water. It seems highly probable, however, that the change in water is accompanied by a fundamental change in the molecular structure, because the violet salt, containing the smaller amount of water, is very much more slowly soluble in water than the green salt, forming like the latter a green solution. We have found that the whole of the chlorine, in the cold green solutions of these cæsium salts, is not precipitated as silver chloride,

thus showing that they agree in this respect with other green solutions of chromic chloride.

It is a curious circumstance that the green chromic sulphate has been considered* to contain less water than the violet modification, while with our cæsium salts exactly the reverse is true, the green salt containing the larger amount of water. It is also remarkable that, while violet chromic solutions are turned green by heat, our violet salt, nevertheless, is produced in hot solutions and the green salt in cold ones. The theory advanced by Krüger and maintained by van Cleefft that the green color of chromic sulphate solutions is due to the formation of a basic salt and free acid or an acid salt, seems hardly applicable to the green cæsium salts, ince it crystallizes from solutions saturated with hydrochloric acid in which a basic salt would seem to be an impossibility. In view of these apparently conflicting facts, it seems necessary to draw the conclusion that the differences in color exhibited by chromic compounds and their solutions are due to more than one cause, probably to the formation of basic salts in certain cases, and also, in other instances, to a change in water of crystallization which is evidently accompanied by a molecular transformation.

Uranyl chloride and cosium chloride.-A careful series of experiments with cæsium chloride and uranyl chloride has resulted in the discovery of but a single salt. This compound, 2CsCl. UO,Cl,, corresponds, except that it contains no water, to the previously described salts, 2KCI. UO,CI,. 2H,O, 2KBr. UO,Br. 2H,O, 2NH C1. UO,C,. 2H,O and 2NH,Br. UO,Br,. 2H,O, but some fluorides of other types have been described.

The compound under consideration forms apparently orthorhombic, yellow crystals which are usually small and blade-like in shape. The products used for analysis were made under the following conditions: Crop A, by making a concentrated aqueous solution of 10 g. of cæsium chloride and 50 g. of uranyl chloride, then running in gaseous hydrochloric acid until crystals began to form and cooling; Crop B, by the same method as above, using 50 g. of cæsium chloride and 10 of uranyl chloride; Crops C and D, by spontaneous evaporation of solutions containing 50 g. of cæsium chloride and 15 g. of uranyl chloride; and E, by the evaporation of a solution of 15 g. of cæsium chloride and 50 g. of uranyl chloride. The results were as follows:

g.