named, pisciculture. He died as he lived, poor and modest, having hardly had opportunity to enjoy the pension allotted to him by government. He expired at 51 years of age in his native village la Bresse (department of Vosges). We have, during his life time, given a short account of his career, which may be found in the volumes of this Journal of the two years past. He left a wife and six children, the oldest of whom, a young man of 30, shows talents similar to his father's, if we may judge from his fulfillment of the charge committed to him by the minister of Agriculture for repeopling the Loire. Monument to Arago. The subscriptions for the erection of a monument to Arago have amounted to a sum sufficient to carry out the plan proposed. A sarcophagus of a simple and severe model, ornamented with wreaths of laurel, and having inscribed upon it the titles of the principal works of Arago, will support his statue cast in bronze. This recumbent statue will be covered by a shroud, the head inclined, the pen falling from his dying hand, as it wandered over the celestial sphere. The execution of this monument has been intrusted to a celebrated sculptor, David Angers, and its completion is expected by the last of May. (To be continued.) Extract from a letter from T. S. Hunt to J. D. Dana, dated Montreal, Canada, March 12, 1855. On the Equivalent of some species.-The crystals of the compound of grape-sugar and common salt, which you have found to be rhombohedral, closely approximating to −2R of calcite*, gave me by analysis 13:31 p. c. of NaCl closely agreeing with the formula of Erdmann and Lehmann, C24 H24O24, NaCl, H2O2, which requires 13:40 p. c. The density of this substance was determined with great care in oil of turpentine, and gave for small well formed crystals the numbers 1.561 and 1.575; two other trials with crystals half an inch in diameter, gave each 1-558. The mean of these four determinations is 1.563 (water being 1.000), and gives for the above formula with an equivalent weight of 436 5, a volume of 279-25, which doubled is 558.5. I had previously, as you know, fixed the volume of calcite and the species homœomorphous with it, at between 555·0 and 564·0, and the present determination seems to confirm the correctness of my view. It is worth while to compare the volume of this compound with those of milk-sugar and cane-sugar, both prismatic species, whose volumes, corresponding like the above to C48, etc., are respectively 464 and 430, according to the determinations of Playfair and Joule. Correct observations upon the crystallization and density of grape-sugar are still required. The crystals of codeine which you find to approach brookite in form, and which may likewise be compared with Barytest, gave me in three *. The crystals are little shorter than broad and present the faces of an acute rhombohedron with the terminal truncating plane O, this last convex. The angle of the rhombohedron, over a lateral edge is 101° 40', giving for the angle over the terminal edge 78° 20'. The angle of -2R in calcite is 78° 51'.-J. D. D. The angles obtained by the writer for codeine using reflected light with the reflecting goniometer are I: 199° 48′, iz: i2=134° 20′, 17: 17-93° 20'. Miller obtained for the corresponding angles 100° 46', 134° 50' and 92° 20'; and Kopp found for the first and last 101° 30' and 92° 30'. If Miller's 134° 50' is right, then his 100° 46' would be by calculation, 100° 30'. The corresponding angles in Brookite are 99° 50' (to 100° 50'), 134° 22' and 93° 16'. These are very near the corresponding angles of Barytes, if 1% be taken as fi.-J. D. D. determinations of density, with large crystals, the numbers 1-302, 1.297, and 1-300 (water being 1000), giving a mean of 1.300, which, with the formula fixed by Anderson, C36H21N 06+H202=317, gives a volume of 244. The density was determined in distilled water, and I convinced myself that the loss by the slight solubility of codeine in this liquid, produced no sensible error. I have made two determinations of the density of transparent cleavable rock salt, in oil of turpentine, and have obtained the numbers 2·137 and 2-134, (water being 1000,) which approach very nearly to that of Kopp, 2:15. Taking as the mean 2.135, we have for the volume 10 Na Cl the number 172, corresponding to the volume of alum, 274. (See this Journal [2], vol. xvi, p. 206.) On the so-called Talcose Slates of the Green Mountains.-Besides the beds of steatite and chlorite slate among the altered Hudson River rocks, there is a great amount of reddish and greenish glossy unctuous slates, which disintegrate very much by the action of the weather, and have hitherto been known by the name of talcose slates. It was however evident that these were formed by the alteration of or dinary clay slates, and I have found by analysis that they contain little or no magnesia, but are essentially silicates of alumina, belonging to the class of minerals represented by pyrophyllite and pholerite, which are aluminous talcs. The nacrile of Thompson from Brunswick, Me., is probably allied to the former, and his talcite from Wicklow, Ireland, to the latter species. In the crevices of a sandstone associated with the above described slates on the Chaudière river, I have obtained a beautiful white mineral in minute pearly scales, whose analysis has afforded me the composition of pholerite. I shall send you soon my detailed results; meanwhile, to avoid the perpetuation of an error, I would suggest for these unctuous aluminous schists the name of nacreous or nacrite slates. On a newly discovered Meteoric Iron.-A large mass of native iron was found last autumn upon the surface of the earth in the township of Madoc, C. W.; it has since been procured by Mr. Logan, the director of the Geological Survey, in the collection of which it has been placed. The mass is rudely rectangular and flattened, but very irregular in shape; its surface is deeply marked by rounded depressions which are lined with a film of oxyd. It closely resembles in appearance the Lockport (N. Y.) iron, with which it seems to agree in composition; a single analysis gave me 6:35 per cent of nickel, in which no cobalt was detected. The iron is very soft and malleable, and from a trial with a small fragment, exhibits a coarsely crystalline structure; the weight of the mass is 370 pounds. We purpose to have it cut, and I shall then be able to make a more complete examination of the iron. On some Ores of Nickel from Lake Superior.-Some specimens from Michipicoten Island, Lake Superior, furnished me by my friend and pupil, Mr. Charles Bonner, have been found to consist of nickeline As Niz, and domeykite As Cu6. The ore was mistaken for the first named species, but is intermixed with a tin-white mineral, often tarnished, which appears to be the arseniuret of copper, since the varying results of sev eral analyses, correspond to different mixtures of the two species. Associated with these is an amorphous earthy mineral with a conchoidal SECOND SERIES, Vol. XIX, No. 57.-May, 1855. 53 fracture; its hardness is not greater than 2, and it polishes under the nail, is translucent on the edges, and falls to pieces when placed in water. Its color is yellowish-green to olive-green. This material is the gangue of native silver and native copper, and is represented as occurring in considerable quantities. It is a hydrous silicate of nickel-oxyd, allied to the nickel-gymnite of Genth, but differing from it in containing less magnesia and some alumina. One of two concordant analyses, executed by Mr. Bonner under my direction, gave, Silica 33 60, oxyd of nickel with a little cobalt 30-40, magnesia 355, lime 4:09, alumina 8.40, peroxyd of iron 2.25, water 17.10-99.39. SCIENTIFIC INTELLIGENCE. I. CHEMISTRY AND PHYSICS. 1. On the specific volumes of fluid compounds-Kopp has resumed his investigation of this very interesting subject and has communicated some new results of much theoretical value. By specific volumes the author understands the relative spaces occupied by equivalent weights of different substances and they are obtained by dividing the equivalents by the corresponding densities. If the equivalents are expressed in grammes the specific volumes will be expressed in cubic centimeters. To institute however a proper comparison between the specific volumes of liquids, the author long since showed that it was necessary to determine these volumes either at the boiling points, or at temperatures equally distant from these and for which the tension of the vapors is the same. Thus the specific volume of alcohol at its boiling point is the sum of the specific volumes of water and ether at their boiling points. Kopp's own elaborate investigations of the densities of bodies at different temperatures, together with those of Pierre on the same subject, have furnished materials for the present instructive comparison. The author in the first place, by the comparison of the specific volumes of a num ber of ethers, as well as of several alcohols and acids, demonstrates the correctness of the proposition formerly advanced by him, that an equal difference of specific volume corresponds to an equal difference of constitution. Thus for a difference of constitution of C2H2 the dif ference of specific volume is about 22. In like manner it appears that when an organic acid passes into the corresponding methyl or ethyl ether, a corresponding change of volume of 22 is produced, thus the difference between Formic acid and formate of methyl is Butyric acid and butyrate of ethyl is 21.3 20.4 19.5 21.5 22.0 21.5 The author's former assumption that fluids of the same empirical form. ula but different rational constitution have equal specific volumes at their boiling points, is confirmed by the following numbers, which at the same time show that-as also formerly advanced by him-equivalent weights of oxygen and hydrogen may replace each other in fluid compounds without a sensible change of volume. Wood-spirit C2H4O2 Formic acid C2H2O4 66 Acetic acid C4H4O4 83.9 62.2 66 106.7 Formate of ethyl C6H604 84.7 Acetate of methyl Acetate of ethyl C8H8O4 107.4 Amylic alcohol C10H1202 123-3 Anhyd. acetic acid CsH6O6 109.9 Buty'e of methyl C10H1004 126-3 Buty'te of ethyl C12H1204 149-7 Alcohol C4H6O2 Valerate of methyl 149.6 The comparison of the specific volumes taken at temperatures equidistant from the boiling points leads to the same results though with less close approximation, while the specific volumes taken at 0 shew but little connection with each other. The author next investigates the questions whether the specific volume of the same elements is to be considered as equal in all liquids at corresponding temperatures and whether the specific volume of a fluid can be expressed simply by the sum of the specific volumes of its constituents, in the case of a compound of carbon, hydrogen and oxygen, for example, by a formula like xc+yh+zo where c, hand o represent the specific volumes of carbon, hydrogen and oxygen in such compounds at their boiling points. According to this formula the specific volume of a compound C Hy Oz ought to be precisely half of that of a compound represented by C2x H2y O2z, and the specific volume of a compound should be equal to the sum of the specific volumes of two others when the formula of the first is the sum of the formulas of the other two. This however proves not to be the case, thus twice the specific volume of aldehyd C4H4O2=1139 while the specific volume of acetate of ethyl C8H8O4 107.4. In like manner C4H4O2+C6H6O2-56 9+77-4-134·3, while C10H1004 126.3. Hence the author infers that in comparing the specific volumes of liquids, only the spaces filled by the true equiv alents and not multiples of these are to be considered. The want of coincidence in the specific volumes of aldehyd and ether is explained at once if we consider the formula of ether to be C8H10O2 as Gerhardt long since proposed. The author leaves it for the present undecided whether it is possible to determine the specific volumes of carbon, hydrogen and oxygen. Although many compounds give the specific volume of carbon 6-3 about, others give somewhat different values; it may be that the data for these latter determinations are inaccurate, and that in all, as certainly in the majority of cases, the specific volume of a compound is simply expressed by the sum of the specific volumes of its constituents and that at corresponding temperatures the same element has the same spec. vol. in all fluid compounds. The author is engaged in the experimental solution of this problem. The specific volumes of fluid compounds may be brought under one point of view by adopting the theory of Gerhardt that water has the formula H2O2 (H=1, O=8) and that the ethers, alcohols and unibasic acids may be considered as derived from water by the replacement of one or both the equivalents of hydrogen by other radicals. Thus when in water (S. V=188 at 100° C.) an equivalentof hydrogen is replaced by an equivalent of ethyl there is an increase of volume of 45 since the specific volume of alcohol is 62.8. When the second equivalent of hydrogen is replaced by one of ethyl the same change of volume occurs and we have 106-2 for the specific volume of ether which agrees with experiment. The same result is obtained for the acids and aldehyds which may be considered as derived from water by the total or partial replacement of the hydrogen by radicals like acetoxyl C4H3O2 and acetyl C4Hз. If C4H3O2 from the specific volume of acetic acid }02=630 we sub tract that of aldehyd C4H3O2 H H =56-8 we obtain 6-2 as the specific volume of the 2 atoms of oxygen which occupy the space of the oxygen in water. The two atoms of hydrogen in water then occupy the space 188-6-2 12.6 and each atom of hydrogen consequently the space 63. From these considerations taken in connection with the results above stated the author makes the following representation of the part played by each element in forming the following compounds. Kopp considers these results as shewing at least that in the acids CHPO4, 2 atoms of oxygen are contained in a different form from the other two. The author concludes his very interesting and able memoir by some judicious remarks on the value of physical characteristics considered in connection with chemical constitution.-Ann. der Chemie und Pharmacie, xcii, 1, October, 1854. 2. On the employment of a solution of chlorid of iron in the galvanic battery. At the suggestion of Liebig, Buff has determined the electromotive force of a galvanic element consisting of zinc in contact with dilute sulphuric acid and carbon in contact with a solution of ses |