down to the 20th of July. They were accompanied by notes of the barometer, the temperature, and the direction and force of the wind. Among the results obtained were the following, as briefly given by Prof. Horsford :

That, other things being equal, the moisture is in general proportion to the temperature; that slight variations of temperature are not accompanied by corresponding variations in the quantity of moisture, and that great variations in the quantity of moisture may take place, while the temperature and altitude of the mercurial column remain constant. The quantity of the moisture, too, has even doubled in the course of an hour, although the temperature became reduced. In general, again, the moisture on the same day seems to depend chiefly on the direction of the wind.

The least quantity of moisture was observed during a northwest or north-northwest wind; the largest, during a southwest or south-southwest wind. The former occurred on the 12th of March, and the latter on the 23d of June last. The quantity on the latter day, remarked the Professor, was to that on the former as more than fifty to one.

The method employed was that of Brunner, which consists of an apparatus for transmitting a known volume of atmospheric air through a chloride-of-calcium tube, previously and subsequently weighed. The difference between the weights before and after the experiment presents the amount of moisture in a given volume of air.

The permeability of atmospheric air to aqueous vapor was established by experiment, and the observations extended through a period of several months. It has been observed, that the striking through of ink employed in writing takes place more promptly in very hot than in cooler weather. A piece of writing-paper of known superficial area was placed in a glass tube closed at one end, and weighed from day to day, noting at the same time the temperature. It was found to weigh more as the temperature was higher.

The quantity of ammonia in the air was determined by an apparatus of the author's construction. The object in view in the arrangement of the apparatus was, to provide that the air should, by means of an aspirator, be transmitted through a constantly renewed atmosphere of hydrochloric acid vapor. To this end, a series of tubes and flasks containing asbestos drenched with hydrochloric acid were connected with a safety-tube, which was connected with an aspirator. Through this apparatus a known volume of air was transmitted. At the conclusion of the experiment, the apparatus was thoroughly rinsed with distilled water, and the ammonia determined in the usual manner with bichloride of platinum. Several determinations having been made, it was ascertained that the quantities of ammonia in the east wind varied considerably from each other; and such was the discrepancy of the Professor's results that he forbore a statement of quantities ascertained, except so far as to remark, that they very greatly exceed those obtained by Fresenius in his recent determinations. One determination was made in a locality in Boston pointed out by one of the police-officers as the worst habitable part of the city, and the atmosphere, which was in the highest degree offensive, was not found to

be distinguished on account of its ammonia above that of the ocean in an east wind.

Continued observations on the state of the atmosphere, made since the reading of this paper before the American Association, show that the quantity of ammonia in the atmosphere is subject to constant variation. In the summer, when vegetable and animal decay is most rapid, the quantity of ammonia in the atmosphere is at a maximum, and afterwards decreases regularly until the winter season, when it is at a minimum. The following table shows the amount of ammonia found in the atmosphere at thirteen different analyses.

SINGULAR COMBINATION OF NITROGEN.

WOHLER, of Germany, has ascertained that the crystals found in the slag of some furnaces, and supposed to be pure titanium, contain both carbon and nitrogen in proportions corresponding with the formula Ti Cy+ 3 Ti3 N. This fact gives us entirely new ideas of the nature of nitrogen, a body supposed to be distinguished above all others for its tendency to take on the gaseous form when its compounds are subject to heat.- Letter of Prof. Liebig to Prof. Horsford.

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GEOLOGY.

GEOLOGICAL SURVEYS OF THE UNITED STATES.

AT the recent meeting of the American Association for the Advancement of Science, resolutions were offered, strongly urging the completion of geological surveys of the several States of the Union which still remain unfinished. There are several cases of this kind, and the interests of the State, the country, and of knowledge, strongly demand that the work be carried forward. Large portions of our territory, rich, it may be, in wealth of minerals, building material, fertile soil, and various productions valuable in the arts, remain unexplored, and, where explorations have been made, there have been delays in the publication of reports, which are not creditable to the legislatures that have this matter in control, nor just to those who have been laboring in the surveys. Silliman's Journal.

GEOLOGY OF THE GOLD REGIONS OF CALIFORNIA.

THE following account of the geology of the gold regions of California is compiled from various sources. The region of the Sacramento is remarkable for the great extent of its alluvial plains or flats. Two hundred miles from its mouth they are twenty miles wide, but near Sutter's Fort the width is between fifty and sixty miles. The country about Sutter's Fort during the winter is mostly covered with water, and the same is true of the bottom-lands of the rivers of the gold region. All the gold thus far discovered occurs uniformly in one geological formation. This is the stratum of drift, or diluvium, composed of a heterogeneous mixture of clay, sand, gravel, and pebbles, and varying in thickness from a few inches to several feet. There are many boulders lying directly beneath the soil, and resting on the rocks below, which, in most of the diggings, consist of gneiss or clay-slate, running about north-northwest and south-southwest, and dipping nearly perpendicularly. The stratum of diluvium is, however, neither horizontal nor of uniform slope, but conformed to the varying inclination of the

earth's surface, covering the declivities, and even the summits of the hills, as well as the bottoms of the ravines and valleys. The sandbars of many of the mountain torrents are extremely rich in metal. Quartz is believed to be the only substance with which the gold is intimately connected. The gold of different localities varies very much in size. That from the banks and sandbars of the rivers is generally in the form of small, flattened scales, and commonly it is found to be finer the lower you descend the stream. That taken from the bottom of dry ravines is mostly of a larger size, and occurs both in small particles and also in small lumps and irregular water-worn masses, from the size of wheat-kernels to pieces of several ounces, or even pounds, in weight. The black, ferruginous sand, which everywhere accompanies the gold, varies in fineness with the size of the accompanying gold.

The slate beds mentioned above often include dikes or beds of quartz rock, in which some have asserted that gold has been found in place, but this still wants confirmation. In some of the richest explorations yet made, however, the slate directly underlies the stratum of diluvium mentioned as containing the gold, and this slate has many crevices or 66 pockets,' ," into which the gold has been washed in considerable quantities, and this fact also has given rise to the belief that gold has been found in place:

In conclusion, there can be little doubt that the gold was deposited in its present position by the same agency and at the same time as the stratum in which it occurs. It is a peculiar fact, that some specimens have been found which appear to have been moulded on regular quartz crystals.

To the east of the gold regions are the mountains of Sierra Nevada, consisting of primitive and metamorphic rocks. In the vicinity of these mountains, the gold and its associated quartz disappear; the rocks underlying the drift appear to consist entirely of gneiss, which is afterwards succeeded by granite.

North of the Bay of San Francisco, talcose slates of various colors have been noticed, and also hills of red and yellow jasper, in layers varying from half an inch to four inches in thickness. At the Straits of Caquines, bluffs of red sandstone, alternating with clayey layers, occur. This sandstone, which is believed to pertain to the eocene period, is soft and easily worked. On a small island near these Straits, gypsum has been found in considerable quantities.

In a letter, dated at San Francisco, October 29th, and published in Silliman's Journal for January, 1850, Rev. C. S. Lyman states that "gold has at last been discovered in place, in veins penetrating quartz beds, on the Mokelemnes and in the vicinity of the Mariposa, and one or two other places. I have this from gentlemen who have seen the veins, and who are reliable witnesses. These veins are of course not worked yet, as it is more profitable to dig the washgold."

The Pacific News for November 30th states that quartz containing gold has been found in inexhaustible quarries through the whole mountainous region which forms the western slope of the Sierra No

vada. Hon. T. Butler King has spent much time in examining this region, and is about making a report upon it to the government at Washington; it will be accompanied by numerous specimens. We have ourselves examined specimens from these quartz mountainquarries, which are in the possession of Mr. Wright, one of the members of Congress elect from California, who will take them on to Washington. They consist, for the most part, of small pieces of quartz rock, generally of a brownish tinge, and, in some instances, presenting the appearance of a slight incipient decay, or decomposition, of the rock formation. In all these specimens the gold points, or particles, are very slightly, if at all, visible to the naked eye. The microscope, however, reveals the gold more clearly. Besides these pieces, which Mr. Wright has himself selected with great care, as the fairest average samples of the general appearance of enormous and very numerous veins, or quarries, of quartz, there is also one larger fragment of the same rock, weighing, we should suppose, some ten or twelve pounds, from all parts of which the gold protrudes plainly in a state almost pure. This single fragment of quartz, which Mr. Wright by no means regards as an average sample of the quarries, but which he pronounces to be the richest rock-specimen he has seen, is found by the most careful specific-gravity test, as applied to it by Mr. Wright, to contain pure gold to the amount of about six hundred dollars.

Mr. Wright has spent much time among the mountains collecting his specimens, and has been assisted by a gentleman conversant with mining operations. The astonishing result brought out by these investigations is, that, in a particular and very extensive vein, four pounds of this rock yielded, upon the average, $11 worth of pure gold, valued at $16 to the ounce; that is to say, the yield of gold from these average samples of the rock in this particular vein is nearly $3 for each pound of quartz. Mr. Wright exhibited to us two small masses of gold, each about the size and shape of a large musket-ball, and both presenting the granulated appearance of gold extracted and collected by the aid of quicksilver. One of these contains about $12 of pure gold, and is the largest yield which has been obtained from 4lbs. of the rock in question. The other contains about $10, and is the smallest yield which has been obtained from any of the experiments upon the rock of this vein. We understand that the tests applied have been sometimes the operation of quicksilver, and sometimes the test of the comparative specific gravity of the pure quartz and the gold-bearing quartz. The Secretary of the Interior remarks, in his Annual Report: "The gold is found sometimes in masses, the largest of which brought to the mint weighed 89oz. They are generally equal to the standard of our coin in purity, and their appearance that of a metal forced into the fissures and cavities of the rocks in a state of fusion. Some masses, however, are flattened apparently by pressure, and scratched as if by attrition in a rough surface. One small mass which was exhibited had about five parts in weight of gold to one of quartz intimately blended, and both together bouldered so as to form a handsome rounded pebble, with a surface of about equal quartz and gold.