walls, at the lowest visible depth; they were there of a pretty bright red, visible in bright winter sunlight overhead. I have no doubt then that the temperature of the shaft at from 300 to 500 feet down was sufficient to melt copper, or from 1900° to 2000° Fahr. "From the extremely bad conducting power of the walls of a volcanic shaft, there is scarcely any loss of heat from any cause, except its enormous absorption in the latent heat, of the prodigious volume of dry steam, which is constantly being evolved. It is perfectly transparent for several yards above the orifice of the shaft, and is not only perfectly dry steam but also superheated; and although this steam may be at the mouth very much below the highest temperature of the hottest point, the temperature of the shaft or duct that carries it off will be very nearly at all depths the same, to probably within a very short distance of the point of greatest incandescence."-Rep. Roy. Soc., &c., Pt. II. chap. xii. vol. ii. pp. 313, 314. The writer respectfully urges that the organization of experiments to determine such data is a subject worthy the immediate attention of the British Association, the Royal Society, and other similar scientific bodies. From recent information he has reason to believe that the existing state of Vesuvius is favourable to such experiments, which the writer is himself prepared to attempt, provided the necessary apparatus and other means be placed at his disposal. The experiments that he would in the first instance propose are (1) The temperature at the mouth or mouths, to the lowest reachable depths within the Vesuvian craters. (2) The temperature of the issuing steam vapours or gases at the mouths, and the degree to which the former are superheated. (3) Approximate determination of the velocity (extreme and mean) of the issuing discharge of steam, &c., with a view to estimation of the volume, in given time, and of the total heat carried off, in same. For the 1st and 2nd, three or more mutually controlling methods may be employed. a. The air pyrometer, or that of Daniell, maximum self-registering. b. The differential bar pyrometer (of two metals), with constant galvanic connexion to the surface. c. The resistance coil thermoscope, also in constant connexion with the surface. The writer, as a practical engineer, has well-founded hope of inserting either or all of these to a considerable and known depth within the crater or craters. For the 3rd, analogous methods should be employed. For the 4th, there is no doubt that Dr. Robinson's anemometer may be so modified as to be made available to determine the issuing velocity in various parts of the column. Into the mechanical arrangements for placing, lowering, and observing, &c. these instruments, it is not necessary here to enter. Vesuvius presents many advantages as a first experimental station; but the inquiry would afterwards be advantageously extended to other volcanic vents. Whatever presumable difficulties may exist, if successfully overcome in the first case, will nearly vanish as regards subsequent repetitions elsewhere. On Meteorology, with a Description of Meteorological Instruments. Meteorological Observations registered at Huggate, Yorkshire. This notice was in continuation of those annually made for many years by the author on the Wolds of Yorkshire, at an elevation of 650 feet above the level of the sea. They contained the annual tables of means, with notes of the days on which the most remarkable events connected with the weather and meteors occurred during the year. On Objections to the Cyclone Theory of Storms. By S. A. ROWELL. Admitting that the winds in storms do at times take a more or less circular course, and that whirlwinds may sometimes occur during storms, the author believed that these are only occasional and minor phenomena in storms, and not the storm itself, as represented in the cyclone theory. He objected to the cyclone theory on the grounds that it is opposed to all the known natural laws which affect the condition of the atmosphere, as he believed it to be impossible that a disk of some hundreds of miles in diameter, but of a mere mile or so in thickness, of air lighter than the general atmosphere, could make its way for days and days in succession through the densest part of the atmosphere, that the evidence in support of the theory is insufficient (this he attempted to show by the aid of diagrams from Reid's 'Law of Storms,' and a general reference to works of the kind), and that the phenomena of the (so-called) cyclone storms may be otherwise accounted for. On the Performance, under trying circumstances, of a very small Aneroid Barometer. By G. J. SYMONS. This instrument, which the author exhibited, had been worn constantly by him recently while at sea in rough weather, while riding and driving over roadless districts in the Orkneys, and also on several occasions when rough climbing and severe jumps had been necessary: he therefore presumed he might reasonably conclude that it had been fully tried. It had been tested before, during, and after the voyage, and had in each case given the same result when compared with mercurial standards. He therefore inferred that it might be considered even less liable to derangement from travel than an ordinary watch. The instrument was very small, being only two inches in diameter and three-quarters of an inch thick. On the Disintegration of Stones exposed in Buildings and otherwise to Atmospheric Influence. By Professor JAMES THOMSON, M.A., C.E. The author having first guarded against being understood as meaning to assign any one single cause for the disintegration of stones in general, gave reasons to show-1st. That there may frequently be observed cases of disintegration which are not referable to a softening or weakening of the stone by the dissolving away or the chemical alteration of portions of itself, but in which the crumbling is to be attributed to a disruptive force possessed by crystalline matter in solidifying itself in pores or cavities from liquid permeating the stone. 2nd. That in the cases in question the crumbling away of the stones, when not such as is caused by the freezing of water in pores, usually occurs in the greatest degree at places to which, by the joint agency of moisture and evaporation, saline substances existing in the stones are brought and left to crystallize. 3rd. That the solidification of crystalline matter in porous stones, whether that be ice formed by freezing from water, or crystals of salts formed from their solutions, usually produces disintegrationnot, as is implied in the views commonly accepted on this subject, by expansion of the total volume of the liquid and crystals jointly, producing a fluid pressure in the pores-but, on the contrary, by a tendency of crystals to increase in size when in contact with a liquid tending to deposit the same crystalline substance in the solid state, even where, to do so, they must push out of their way the porous walls of the cavities in which they are contained, and even though it be from liquid permeating these walls that they receive the materials for their increase. CHEMISTRY. Address by Professor W. H. MILLER, M.A., F.R.S., President of the Section. ONCE in about a quarter of a century a mineralogist is placed in the chair of the Chemical Section of the British Association. This procedure is not without its inconvenience: many important questions are likely to present themselves during the meetings of the Section which a mineralogical president can rarely be competent to decide. In another point of view, however, this arrangement is more satisfactory; it is symbolical of the removal of a barrier which once threatened to separate mineralogy from chemistry, to the serious detriment of both. While some mineralogists sought to exclude chemistry from their systems, chemists intent upon discovery in the newly opened field of organic chemistry neglected mineral analysis. But of late these mutually estranged sciences have exhibited a growing tendency to reunite, and to aid one another. The chemists now freely admit the mineralogists as their associates, not unfrequently sharing their labours, and include geometrical and optical characters in the descriptions of the new combinations they discover. Of this we have instances in the memoirs of Kopp, Rammelsberg, Hofmann, Sella, Marignac, Des Cloizeaux, and in those of Haidinger, Leydolt, Grailich, Dauber, Schabus, v. Lang, Schrauf, v. Zepharovich, Rotter, A. and E. Weiss, Murmann, and Handl. The experiments on the formation of minerals, commenced by Berthier and Mitscherlich, have since been varied in almost every possible way. Ebelmen, de Sénarmont (whose recent death is a grievous loss to the sciences we cultivate), Daubrée, Wöhler, Manross, and H. Deville have successfully imitated the processes of nature in producing a large number of crystallized minerals in the laboratory, and thus have helped to obliterate the boundary arbitrarily drawn between the studies of the chemist and those of the mineralogist. The memoirs I have cited in proof of the intimate connexion of chemistry and mineralogy deserve our especial attention for another and more important reason. The observations they record, being made on crystals of accurately known composition, far exceeding the crystallized minerals in number, and differing from minerals in being quite free from any admixture of foreign matter, furnish the only data from which we may hope that some future Newton of the science will be enabled to discover a simple law of the dependence of the form, optical and physical properties of crystallized bodies on the substance of which they are composed. On the Formation of Organo-Metallic Radicals by Substitution. The object of this inquiry was to investigate the order in which the metals of the organo-metallic radicals were capable of substitution, through the agency, in the first place, of simple metals, in the second place, of salts of simple metals, and in the third place, of salts of other organo-metallic bodies. It was found that when metals acted upon these radicals, substitutions were affected, in the greater number of cases, in the order indicated by the ordinary electro-positive or electro-negative position of the contained metals. Exceptional cases, however, occurred. By the action of sodium on mercuric ethyl, the mercury is partly extruded, and a double compound of mercuric and sodium-ethyl is obtained. By the action of chloride of cadmium on zinc-ethyl, appreciable quantities of cadmium-ethyl were formed, which, however, could not be satisfactorily separated, either by distillation or the action of anhydrous solvents, from the unctuous mass of chloride of zinc which is one product observed. Mercuric ethyl and bichloride of tin react powerfully with the evolution of much heat, and result in the separation of chloride of mercuric ethyl and chloride of stannic sesquiethyl, according to the equation Terchloride of antimony, on the other hand, is converted by mercuric ethyl into triethylstibene, the whole of the chlorine passing over to the mercuric radical. From the circumstance that titanium, in many respects, imitates the behaviour of the metal tin in its combinations, experiments were made with the bichloride. Zinc-ethyl strongly reacts upon this body, if assisted by gentle heat. Chloride of zine is formed, but gases are immediately disengaged if distillation is attempted, Bichloride of titanium and stannic diethyl result in the reduction of the bichloride to the condition of sesquichloride, whilst the oily chloride of stannic sesquiethyl separates according to the equation The paper concluded with considerations upon the possibility of substituting ethyl for oxygen in the organo-metals, and also remarked upon the question, possessed of considerable interest, how far, and in what manner, the introduction of different metals can be effected in the organo-metallic radicals, represented by the type Can RR be represented by different metals, in the same manner as X may represent different alcohol radicals? The author hoped shortly to be in a position to answer this inquiry. On the Action of Nitric Acid upon Pyrophosphate of Magnesia. By DUGALD CAMPBELL, Analytical Chemist to the Brompton Hospital, London. When pyrophosphate of magnesia was dissolved in ordinary nitric acid, and exposed in an open capsule to temperatures ranging from 320° F. to 550° F. till the weight became constant for each temperature, it was invariably found to have increased very much in weight, although not always to the same extent, as shown below: Temperature. 420 550 Difference, 8 per cent. 2 When the pyrophosphate of magnesia, still retaining nitric acid, but constant in weight at 3200 F., was heated sufficiently to drive off all the nitric acid, it was found to have decreased in weight, not to a uniform amount, but varying from 9 to 15 per cent., according to the greater or less rapid application of heat; on heating in the same manner the pyrophosphates of magnesia retaining nitric acid, and constant in weight at 430° F. and 550° F., they were found likewise to have decreased much in weight, although not to so great an extent, by pyrophosphate of magnesia being volatilized along with the nitric acid. It is inferred from these experiments that nitric acid has a stronger affinity for magnesia than pyrophosphoric acid has, and that on adding nitric acid to pyrophosphate of magnesia, nitrate of magnesia is formed, pyrophosphoric acid being liberated; and this was proved to be the case by dissolving pyrophosphate of magnesia in nitric acid, evaporating the solution till syrupy, and then placing it under a bell-jar over sulphuric acid; after a time nitrate of magnesia crystallized, and pyrophosphoric acid could be drained off. But although nitrate of magnesia is formed and pyrophosphoric acid set free on the addition of nitric acid to pyrophosphate, it is probable that, when this mixture is evaporated and heated, the products are not always mere mixtures of nitrate of magnesia and pyrophosphoric acid, but that they are sometimes compounds; and the reasons for this opinion are, that these products are but slightly deliquescent, that nitric acid is less readily expelled from them than from nitrate of magnesia, and that on heating these products suddenly, pyrophosphate of magnesia is volatilized, though it is not under ordinary circumstances a volatilizable salt. From the above results, the author recommends the discontinuance of moistening the pyrophosphate with nitric acid when calcining it, when estimating phosphoric acid or magnesia, as it may be apt to lead to a source of error. Mémoire sur les modifications temporaires et permanentes que la chaleur apporte à quelques propriétés optiques de certains corps cristallisés. Par A. DES CLOIZEAUX. On sait, d'après d'anciennes recherches de MM. Brewster et Mitscherlich, que dans certains cristaux l'écartement des axes optiques et l'orientation de leur plan varient avec la température. Pendant longtemps on n'a guère connu que les phénomènes si tranchés qui se manifestent dans la Glaubérite et le gypse. J'ai constaté récemment qu'un assez grand nombre de substances anhydres ou hydratées, telles que le feldspath orthose, la Heulandite, la Prehnite, le clinochlore, la cymophane, la Brookite, &c., subissaient aussi l'influence de la chaleur d'une manière plus ou moins marquée; mais de plus j'ai découvert que si l'on élevait suffisamment la température, ce qu'il est facile de faire pour l'orthose, la cymophane et la Brookite, par exemple, les modifications optiques, de temporaires qu'elles sont lorsqu'on ne dépasse pas 300 à 400 degrés Centigrades, deviennent entièrement permanentes. Le minéral qui, par sa transparence et son homogénéité, se prête le mieux aux expériences les plus variées et les plus exactes, est un orthose vitreux de Wehr dans l'Eifel, et c'est sur une plaque de cette nature que j'ai obtenu les résultats suivants. |