Dec. 4. The aneroid barometer was placed under the receiver of a condensing-pump, when it was observed that it would only move up to thirty-one inches (corresponding to thirty-one inches of a common barometer).

TABLE III.

Observations in Table II., arranged according to the Amount and the Sign of the Differences.

1849, Sept. 10. The aneroid stood at 30.39. It was placed under the receiver of an air-pump, and the atmospheric pressure diminished by five inches. When the air was admitted, the index moved forward to 30.35. It rose to 30.375 in two or three minutes. The following table embraces similar experiments, with their results.

Dr. C. T. Jackson exhibited some specimens of native copper, and gave a verbal account of some of the evidences of ancient Indian mining at Lake Superior. Dr. A. A. Hayes stated that the occasion of these samples being on the table was a proper one for him to take, in communicating the fact, "that, from extended observations, embracing more than five hundred specimens of the Lake Superior native copper, no instance occurred in which the slightest indication was presented of this copper having been fused in its present condition. I have investigated its internal structure, by a new method of analysis, which permits all alloys and foreign matters to fall on one side, while the pure copper is separated and weighed as such on the other. In this way, and by little modifications, the highly crystallized structure is exposed to view, the less regularly polarized portions being removed. Whether we subject the solid thick masses, or the thinnest plates, to the operation, one constant result is obtained; that this copper has taken its present varied forms of crystallized masses, more or less flattened, laminated, or grooved, by the movements among the parts, composing the rocks in which it is found. If we select a mass which has entered a cavity, we find the crystals with their angles sharp and uninjured, while the mass mainly may have been compressed into a plate. Dissecting this, the crystals are seen to be connected with and form parts of the original system of crystallization. Flattened and grooved specimens often present on their edges arrow-head-shaped forms, derived from regular crystals, crushed and laminated.”

Dr. Hayes, having alluded to a new method, a kind of proximate analysis of metals and alloys, further stated, that it is one which admits of almost universal application. Operating on irons of commerce, he has demonstrated that phosphorus and sulphur, usually found to be present, are not united to the iron, but with more highly electro-positive metals, such as potassium, sodium, and calcium, the latter most commonly. And in all alloys thus far examined, the compound is a metal in a pure homogeneous state, while one, two, or three definite alloys are distributed, often unequally, throughout the mass. In some tough metals, brittle substances like iron ores, quartz, &c., are found, rendering the method of research one of great interest and importance.

Dr. Hayes called the attention of the Fellows to the fact, that

"The urinary deposition called red sand, which presents such welldefined crystals, is a compound body, having generally a large quantity of oxalate of lime crystallized with it. Crystals of various forms and colors were shown under the microscope. Lithic acid, ammonia, coloring matter, and oxalate of lime are the most common and obvious ingredients assuming a crystalline form. Oxalate of lime, as inferred from more than twenty-five analyses of different urine samples, is always present, and may be detected both by spreading a layer of aqua ammonia on the surface of recent urine, when the salt crystallizes, and by adding hydrochlorate of lime to recent urine, washing the precipitate and subsequent analysis. Recent healthy urine is always acid; but this state is not produced by carbonic acid, united to the phosphates, as has been supposed. When salts of lead, lime, baryta, or magnesia are added, the acidity is preserved unchanged. The carbonic acid usually present is disengaged by a powerful acid, with the effervescence due to its gaseous form, but, independently of this, there exists an acid reaction. It has been assumed that oxalic acid is absent in cases where no crystals of oxalate of lime separated from samples of urine preserved. If the acid action is very marked, such cases are no exceptions, for in urine we do not expect unfailing chemical decompositions of salts. Besides, it can be shown that, even in alkaline urines, oxalate of lime separates as red sand, and covers the surface after several days of exposure for deposition. These, with other observations, lead to the conclusion, that we are far from possessing a true knowledge of the composition of this important secretion. A true analysis can only be made by operating on recent urine, by precipitations and evaporations, without loss of time and aid of heat; the more important constituents are otherwise converted into secondary products of the steps of the analysis."

Professor Horsford read a paper from Mr. Breed of the Lawrence Scientific School, giving an account of a series of experiments on the nature of vesication, and showing that the process was totally independent of evaporation.

Professor Horsford also exhibited a Daguerreotype of the moon, taken in front of the eye-glass of a telescope, by Mr. Wells of the Scientific School.