numbers. The year 1843 was, however, a minimum epoch of the eleven-year cycle. It would seem, therefore, that the formation of this extraordinary spot was an anomaly, and that its origin ought not to be looked for in the general cause of the spots of Schwabe's cycle. As having a possible bearing on the question under consideration let us refer to a phenomenon observed at the same moment, on the first of September, 1859, by Mr. Carrington, at Redhill, and Mr. Hodgson, at Highgate. "Mr. Carrington had directed his telescope to the sun, and was engaged in observing his spots, when suddenly two intensely luminous bodies burst into view, on its surface. They moved side by side through a space of about thirty-five thousand miles, first increasing in brightness, then fading away. In five minutes they had vanished. *** It is a remarkable circumstance, that the observations at Kew show that on the very day, and at the very hour and minute of this unexpected and curious phenomenon, a moderate but marked magnetic disturbance took place; and a storm, or great disturbance of the magnetic element, occurred four hours after midnight, extending to the southern hemisphere." The opinion has been expressed by more than one astronomer that this phenomenon was produced by the fall of meteoric matter upon the sun's surface. Now, the fact may be worthy of note that the comet of 1843, which had the least perihelion distance of any on record, actually grazed the solar atmosphere about three months before the appearance of the great sun-spot of the same year. The comet's least distance from the sun was about 65,000 miles. Had it approached but little nearer, the resistance of the atmosphere would probably have brought its entire mass to the solar surface. Even at its actual distance it must have produced considerable atmospheric disturbance. But the recent discovery that a number of comets are associated with meteoric matter, traveling in nearly the same orbits,|| suggests the inquiry whether an enormous meteorite following in the comet's train, and having a somewhat less perihelion distance, may not have been precipitated upon the sun, thus producing the great disturbance observed so shortly after the comet's perihelion passage. ART. XLII.-Calorimetric Investigations; by R. BUNSEN.* (Continued from page 179.) The Ice Calorimeter. In order first to become better acquainted with the phenomena attending the formation of ice, although only in so far as they come under consideration in using the instrument, the calorimeter, containing a cylinder of ice and carefully surrounded with snow, was kept long under observation. It stood, as in all the following experiments, in a large earthenware decanting jar, through whose lower orifice the water dropping from the melted snow could continually flow off, so that a contact between the lower part of the instrument and the water thus formed was not to be feared. The instrument soon surrounds itself with a coherent mass of semisolid snow (firneis). If, after twelve or fifteen hours, a considerable cavity has been formed on the walls of the jar by the external melting of this mass, this cavity is then increased by smoothing off the loosely coherent substance with a spatula-shaped stick, the portions thus scraped off being stuffed into the vacent spaces under the calorimeter, and the snow lost by melting replaced with fresh. The first experiments were made with freshly fallen snow, which had been collected from a clean substratum of the same substance, and carefully shielded from every contamination arising from the soil. Of this snow, one hundred weight was preserved in a clean wooden chest, as a stock for the refillings during the experiments. With such a stock the calorimeter may by filling up twice daily, be kept for weeks in continual use without the necessity of renewing the ice-cylinder. Throughout the entire duration of the observations, which occupied five days, the inner vessel enclosed in the ice-cylinder was kept closed with a rubber stopper, and the whole instrument, with the exception of the scale, surrounded on all sides with melting snow. The temperature of the room in which the observations were made varied between 0°5 C. and 6° C. The observations are presented in the following table 1. Column I, contains the time of the observations in hours. Column II gives the readings of the calorimeter scale for these times; the observed values are characterized by a star, the others have been calculated from these by interpolation. Up to the thirtyfirst hour the mercury which left the graduated tube was weighed; and the weight thus found transformed into scaledivisions according to equation (1). Column III has been calculated with the aid of equation (3), and gives the weight of * Translated for this Journal, with permission of the author, from Poggendorff's Annalen der Physik und Chemie, Bd. cxli, by Dr. G. E. MOORE, of San Francisco. the ice, expressed in grams, which has been formed in the instrument from the beginning of the period in question. The table shows that about two grams of the water, contained in the calorimeter, froze at the temperature of melting snow during the first seven hours, that this freezing at the temperature of melting snow continued 114 hours in diminishing ratio, and that after this long time a period began, in which the water did not freeze further at the temperature of melting snow. The disproportionately great formation of ice at the beginning of the experiment arose evidently from the low temperature which the cylinder of ice, formed at -15° C. to -20° C., originally lq possessed, as the following consideration shows. Let it be assumed that the amount of ice g, formed during the first seven hours originated in the loss of heat which the water suffered in order to warm the ice-cylinder from -1° to 0° C., then will the mean temperature, which the ice-cylinder must have had in order to produce the above named weight of ice, result from the equation=- wherein I signifies the heat of melting for water, s, the specific heat of ice, and G the weight of the ice-cylinder cooled to t°. In this equation only G is unknown. After the termination of the series of experiments in table 1, in order to determine G, the open end of the scale tube was dipped into a weighed glass vessel full of mercury, and, after the ice cylinder had melted and the instrument had been brought again to 0° C., the loss in weight G, of the mercury vessel was ascertained. The desired weight of the ice-cylinder is G G1P, wherein s, signifies the specific gravity of mercury as = Sqv 0° C., p the weight of melted ice corresponding to one division. on the scale (equation 3), v the volume of one scale division (equation 1). The values of the terms occurring in this and the preceding equation are: Sw=0·48 By the substitution of these values in the equation there results, as the weight of the ice cylinder used in the observations G= 49 65 grm. t=-6°.95 Č. and for its temperature The ice cylinder, which had been produced at a temperature of at least 15° C., needed therefore to have possessed, at the time the instrument was placed in the snow, a temperatue -7° C. only, in order to have produced by its warming to 0° C. the formation of ice observed during the first seven hours. As from the determination of specific heat communicated beyond, it may be concluded that a period of seven hours is far more than sufficient to equalize a difference of temperature of 7° C. in the instrument, it is necessary to ascribe the ice formation which is visible in the table and which lasted more than 100 hours, to another cause than the one under consideration. Without entering further into the question whether this cause is to be sought for in the air contained in the snow water, as C. Schultz* assumes, or whether the passage of the snow to the semi-solid state (firneis), plays therein a part, it may suffice in the first place, to give prominence only to those influences determining * Pogg. Annalen, cxxxvii, 253. a lowering of the melting point of ice, which are particularly deserving of attention in the employment of the ice-calorimeter. If the pure snow which surrounds the instrument be saturated with as much boiled-out or distilled water of 0° C., previously shaken with air, as it can retain after the excess has been allowed to drain off, there ensues, at least during the first twelve hours, during which alone the observations were carried on, no freezing but such a melting of the ice in the interior of the instrument that it would, under these circumstances, be entirely unserviceable for observation. On the other hand the slightest impurity of the snow determines such a large continual deposition of ice on the ice cylinder, that the mercury thread often advances in one minute several divisions on the scale. Snow which has absorbed even traces of salts from the soil, or of animal, or vegetable impurities from the street pavement, shows this lowering of the melting point in the most striking manner. River ice of such purity that the water obtained from it by melting, showed with barium chloride and silver solution only after a long time, a scarcely perceptible turbidness produced in the instrument during three days two grams of ice. After these observations it is self-apparent that only the purest snow can be used in the experiments. It is also advantageous to work in an apartment whose temperature is not too high above 0° C., and not to begin the observations, until the formation of ice on the ice-cylinder does not exceed a few scale divisions in the hour. Above all, however, care must be taken that, before the instrument is allowed to take, in the snow, a constant temperature, a small layer of water has been formed by melting between the glass walls and the adjacent ice-cylinder, in order that unequal tension and its consequent elastic after-effect may be avoided. The accuracy of the, observations depends, however, most essentially upon the care which has been taken in the original arrangement of the instrument, that all the air absorbed by the mercury and water be removed. This is to be attained in the following manner: the instrument, filled to the half with boiled out water, is fastened with the mouth turned downward on the arm of a retort-holder, the mouth of the tube c, fig. 1, which is not yet provided with an iron casing, is sunk in water which is kept in constant ebullition in a beaker-glass, and the water in the instrument which reaches to kept boiling until it has evaporated to . If now the lamp used to heat the apparatus be removed, the latter will fill itself with airless water. It is allowed to cool and is then, after it has been placed upright as in the drawing, filled to the height with so much freshly boiled-out mercury, that the mercury level in the vessel b stands about equally high with that in the tube c. The water |