I know at present of no such description, and am unable therefore to enter into any explanation which could be relied on, having received my information from those who were perfectly ignorant of the subject. I shall therefore confine myself to a mere description of the specimen which I have obtained, and to an analysis of it.

Its mineral characters are as follows.

In colour and lustre it resembles metallic lead.

Its brilliancy is greater than the generality of ores of Galena.

Its structure is laminated and compact.

It is very brittle and easily divisible into fragments which generally assume the cubic form.

Specific gravity, 7,50.

I am also in possession of several specimens crystallized in a very curious and interesting manner. These specimens consist of groups of cubic crystals, from the most minute that is possible, to the size of one fourth of an inch, confusedly placed on each other, all of them are perfectly defined, exhibiting the planes of the four sides in a very distinct manner; and the structure of the large crystals, it is evident from the appearance of the surface of the plane, arises from an aggregation of smaller ones of the same form.

The specimens which I have seen are frequently intersected by small veins of calcareous spar, and to many of them are attached particles of white fine grained primitive lime-stone. I have also seen specimens of sulphate of barytes from the same place, of a tabular form, perfectly white and bevelled at the edges, containing imbedded in them cubic crystals of galena.

These circumstances show what the matrix of the ore is, and that it is not found in loose masses imbedded in clay, as has been repeatedly told me, but that it occurs in the usual manner imbedded in solid strata, or occasionally in detached masses, but always accompanied with carbonate of lime or sulphate of barytes as its matrix.

One hundred grains of the most compact variety of this ere finely pulverized was digested with six times its weight of nitric acid, of specific gravity 1,3 diluted with two parts of water; when all action seemed to have ceased, I poured off the solution and repeated the process three different times, successively keeping up for several hours a very moderate heat with a lamp. During the digestion a light flocculent powder appeared on the surface which in a short time subsided to the bottom of the flask.

Having collected these solutions and weighed the precipitate when perfectly dry, it was found to contain twenty-eight grains, which when thrown on ignited charcoal burned away with a sulphureous vapour, leaving only a residuum of four grains which consisted of silex and oxyd of iron.

Into the solution obtained from the nitric acid I gradually poured a small quantity of muriatic acid; a copious white precipitate immediately appeared, which soon subsided to the bottom; continuing to drop in muriatic acid till no farther cloudiness took place; I let it rest till the fluid was perfectly clear, a quantity of crystals of a white colour was found at the bottom of the flask, which of course were either muriate of silver or muriate of lead, or both. The clear solution was afterwards poured off, and the precipitate carefully washed with alcohol, and dried, when it was found to weigh 96 grains. In order to separate the lead from the silver, if any was present, I boiled it in a sufficient quantity of distilled water which has no action on muriate of silver, but in a certain proportion of which, muriate of lead is completely soluble. The whole of the precipitate was in a short time taken up, except so minute a portion of it, that it was impossible to collect and weigh it with any precision. It therefore appears that this ore contains but a very minute proportion of silver, and that calculating as has been ascertained, that 100 parts of muriate of lead contain 75 of metallic lead, this ore according to this experiment contains 72 per cent. of that metal.

1

To ascertain whether the ore contained any copper, I poured a few drops of Ammonia on the nitric solution after the precipitation of the lead by the marine acid, but no change of colour took place, which would have been the case had the most minute quantity been present.

To determine whether the solution contained iron, I pouron it a small quantity of prussiate of potash, which immediately changed the solution to a blue colour, exhibiting the traces of iron, but in such small quantity that no precipitate could be obtained from it.

Thus it appears that the constituent parts of this ore are nearly as follows.

In the quantity of lead in particular, I conceive that I am tolerably accurate, as my attention was chiefly drawn to ascertain the proportion of that metal which it contained.

It may not be superfluous to observe here, that the general opinion which prevails, that these ores of galena which exhibit the greatest metallic brilliancy and lustre are the richest in silver, is in general erroneous, as appears from the result of the above analysis, and which I hope to have an opportunity of shewing more fully, in a comparison between this ore and another of a very different appearance which I am at present engaged in examining.

Jameson adds to this observation, another, which I have also found equally correct; such as, that those ores of galena which are found imbedded, or in large masses, are never so rich in silver as those which lie compressed in veins of solid strata. Those facts I hope to have the pleasure of more fully illustrating in a second communication to your highly valuable Journal.

IV. A Geological account of Dutchess county in New-York, by DR. SAMUEL AKERLY, in a letter to the Editor.

DEAR SIR,

My visit to Dutchess County during the month of August last, offered me subjects of reflection which may be worthy of a place in your Mineralogical journal, for which purpose I now present the observations thence resulting for your acceptance.

Dutchess County lies between West-Chester on the south and Columbia-County on the north, having the Hudson river on the west and Connecticut on the east. It has an extent of about 60 miles in length from north to south, and about 24 in breadth. This county had a population exceeding 60,000 at the last census taken in 1801.

The introduction of Gypsum of late years has greatly improved the agriculture in this and the neighbouring counties. The hills in Dutchess County, though numerous, are capable of cultivation to their very tops, excepting the highlands and a few that are more abrupt than the generality of them, being all however well adapted to the raising of merino sheep which have already made a rapid increase. Bread and Indian corn may be considered the staple commodities of this county.

Not being sufficiently acquainted with the county to form a statistical account of it, I return from this digression to give a geological view of it; for this purpose it may be considered under the heads of Granite, Slate and Lime-stone.

GRANITE.

That part of the highlands on the east side of the Hudson, is included in the south part of the county. These mountains consist of masses of granite, containing most of the materials that enter into the composition or aggregation of this primitive rock, under the distinctive appellations of gneiss, shistose mica, granatine, granitelle, shorl, trap, hornblend,

&c. The region occupied by these mountains covers a space of about 300 square miles. Very few of them exceed a thousand feet in elevation above the surface of the Hudson river. Antony's nose, as measured by the British during our struggle for Independence, is laid down on a map made under the directions of Lord Howe in 1777, to illustrate his proceedings against the colonies, at 1128 feet. The mountains of the highlands abound in ores, Iron however being the principal one that has yet been extracted and worked to advantage. That other valuable ores may be found in these elevated ridges, I have no doubt, and I have been assured by a person who had followed mining in Europe, that he had in this county, met with the ore of tin and some others of which he was uncertain as to their nature, at the same time remarking, that he was surprised at the facility with which metals in this country may be obtained, as the indications were so very evident, the metals themselves frequently ap pearing on the surface of the earth.

Few other hills in this county, are granitic besides the highlands. In the town of north-east in the upper part of the county, there is one nearly a thousand feet elevated above the surrounding country, consisting of grey granite. It may be remarked of this mountain, as I have before, respecting the Shawangunk mountains in Ulster and Orange Counties in my letter to Dr. Mitchill (Med. Repos. Hex. 2. vol. 3. p. 324) that the eastern declivities are steep and abrupt, while the western descend on an inclined plane forming a small angle with the horizon. Beneath the eastern declivity, down which I descended with difficulty, lies a small lake the head waters of Wappingers creek, which empties into the Hudson between Poughkeepsie and Fishkill. The water of this lake is very clear and transparent to a considerable depth, containing a number of fish and the water lily, (Nymphea advena of Aiton) in abundance where the water is not too deep for its growth. While fishing in the lake, my attention was drawn to the great discharge of air, from the