0° C. From this it would follow that the resistance of the simple metals in the solid state to electric conduction, is nearly proportional to the absolute temperature. The author remarks that although this conclusion is not yet fully borne out by experiment, the numbers obtained being only approximate, it may yet be of interest and serve as an inducement to new investigations.-Pogg. Ann. civ, 650. 3. On the expansion of liquids heated above their boiling points.-THILORIER found in 1835 that liquid carbonic acid between 0° and 30° C., has a mean coefficient of expansion of 00142, which is about four times greater than that of air and other gases. Drion has endeavored to generalize this observation, and finds, in fact, that other volatile liquids at temperatures sufficiently above their boiling points, exhibit coefficients of expansion of similar magnitude. The following are the author's results for chlorhydric ether and sulphurous acid. The coefficient of expansion of chlorhydric ether at 0° is according to Pierre 0.00157. According to Drion the apparent expansion of the same liquid is 0.00360 of its volume, at 121° C. upon the average for every degree centigrade. Between 128° and 134° the coefficient is 0.00421 of the volume at 128°, while between 144°.5 and 149°-25 the coefficient is 0.00553 of the volume at 144-5. The mean expansion of sulphurous acid between 0° and 18° is 0-00193. Between 91° and 99°5 the coefficient is 0.00368 of the volume at 91°; between 108°.5 and 115°5 it is 0.00463 of the volume at 108°.5; between 116° and 122° it is 0.00533 of the volume at 116°; between 122° and 127° it is 0.0060 of the volume at 122°. From this it appears that the coefficient of expansion of chlorhydric ether becomes equal to that of a gas at a temperature of about 125° C.; that of sulphurous acid equals that of a gas at about 95° C. Above these temperatures the coefficients increase very rapidly.-Comptes Rendus, xlvi, 1235. 4. On the chemical effects of electric discharges.-PLÜCKER has published in successive parts, the results of an elaborate and very interesting investigation of electric discharges in tubes containing rarefied gases. For the details we must refer to the original papers, which do not admit of condensation, and content ourselves with giving in the author's own words, the results which are most interesting to chemists. I. Certain gases (oxygen, chlorine, bromine and vapor of iodine,) combine more or less slowly with the platinum of the negative electrode, and the resulting compounds are deposited upon the surrounding sides of the glass tube. When the gases are pure we approximate in this manner to a perfect vacuum. II. Gases which are composed of two simple gases (vapor of water, ammonia, protoxyd of nitrogen, deutoxyd of nitrogen, nitrous acid,) are immediately separated into their components, and then remain unchanged, if they do not (as ammonia) unite with the platinum. If one of the gases be oxygen (as in steam and the different oxyds of nitrogen) this gradually disappears and only the other gas remains. III. When the gases are composed of oxygen and a solid simple substance, complete decomposition by the current takes place but slowly, the oxygen going to the platinum of the negative electrode, (sulphurous acid, carbonic oxyd, carbonic acid). Carbonic acid at first splits instantly SECOND SERIES, VOL. XXVII, No. 80.—MARCH, 1859. into the lower gaseous oxyd and into free oxygen, which combines gradually with the platinum. Carbonic oxyd gas is then slowly decomposed by the combination of its oxygen with the negative electrode. The results above mentioned, were obtained by means of the so-called Geissler's tubes, which are simply glass tubes of various forms containing rarefied gases, and provided with platinum wires fused into the glass. The electric currents were partly derived from the electric machine, and partly from Ruhmkorff's apparatus. Finally, the results themselves are directly deduced from the prismatic analysis of the light of the simple and compound gases, the spectrum obtained being simple, or composed of two distinct and superposed spectra, according as the discharge passes through a simple gas or a mixture of two.-Pogg. Ann., cv, 67. W. G. 5. On a new Law of Binocular Vision; by the Rev. J. DINGLE, (Proc. Brit. Assoc., Ath., No. 1615).-The object of the law in question is to obviate the imperfect vision which would sometimes arise from the difference of the pictures in the two eyes. In some cases this difference would lead to great inconvenience and confusion. It sometimes happens, for instance, that in looking at a field of view at some distance, objects considerably nearer are so interposed as to present themselves in the picture formed in one eye and not in the other. Thus, in looking at a landscape, if the finger or any other object is held before one eye, the image of it from the one retina is superposed in the sensorium on a part of the landscape formed in the other eye. On mere physical principles, this might be expected to blot out or greatly confuse that part of the landscape upon which it was placed; but upon trial this is not found to be the case, as that part is merely a little dimmer than the rest from being seen only with one eye, but is equally distinct and as truly colored. By various experiments the author had ascertained that this was the result of a peculiar power of the will, by means of which the mind is enabled, when two different images are superposed in the sensorium, to select whichever it pleases, to bring that object into view, and entirely to obliterate the other, it sees, in fact, whichever it wills to see, and the other image, simply by being neglected, becomes invisible. In ordinary vision, the determination of the image to be seen is effected by the same act of the will which determines the position of the optic axes; but by certain arrangements which were indicated both images may be made to have the same relation to the optic axes; and as the predisposition to select one or the other is thus obviated, it is made indifferent to the mind which of the two images that occupy the same place in the sensorium it shall see. When these arrangements are made, it is found that mere efforts of the will can easily bring either the one or the other into view. The importance of this law, which enables the mind to select its image, was pointed out in different cases of ordinary vision. It obviates the difficulty already adverted to, of having two different pictures on the same spot; it has not improbably an important influence in producing the general stereoscopic effect; it also, to some extent, remedies the effect of squinting, by obliterating the picture in the imperfect eye, which could not be else done without shutting it. The effect of the law, in some extraordinary cases, was also noticed, especially in the power of the will to fix images on the sight, as Sir Isaac Newton instances in his own case (see his life by Sir David Brewster). The author pointed out the great interest of the subject, not only in its practical aspect, but also as having an important bearing on the connexion between mind and matter. Prof. Stevelly said that in reference to these permanent impressions on the retina so well described in the very interesting letter from Sir Isaac Newton which had been read, he wished to mention a circumstance which occurred to himself this summer, and which he was entirely unable to account for on any optical or physiological principle with which he was acquainted. At the close of last college session he had been in weak health, and had gone out to his brother-in-law's seat in the country for a few weeks. While there he had become greatly interested in the economy and habits of the bees. "One morning, soon after breakfast, the servant came in to say, that one of the hives was just beginning to swarm. The morning was a beautifully clear, sunny one, and I stood gazing at the insects, as they appeared projected against the bright sky, rapidly and uneasily coursing hither and thither in most curious yet regular confusion, the drones making a humming noise much louder and sharper than the workers, from whom also they were easily distinguished by their size; but all appearing much larger in their rapid flights than their true size. In the evening as it grew dark, I again went out to see the bee-hive, into which the swarm had been collected, removed to its stand; soon after I was much surprised to see, as I thought, multitudes of large flies coursing about in the air. I mentioned it to my sister-in-law, who said I must be mistaken, as she had never seen an evening on which so few flies were abroad. Soon after, when I retired to my chamber, and knelt to my prayers before going to rest, I was surprised to see coursing back and forward, between me and the wall, what I now recognized as the swarm of bees, the drones quite easily distinguishable from the workers, and all in rapid whirling motion as in the morning. This scene continued to be present to me as long as I remained awake, and occasionally when I awoke in the night, nor had it entirely faded away by next night, although much less vivid. This was the first instance I had ever heard of moving impressions having become permanently impressed on the retina, nor can I give the slightest guess at the modus operandi of the nerve. Notices of fixed impressions, particularly after having been dazzled, are now common enough. The Rev. Dr. Scoresby, at the late meeting at Liverpool, had given a detailed account of some which had presented themselves to him; and a very curious one had occurred to me some years since. I was walking down the streets of Belfast with Sir John Macneill, the eminent engineer, when he said to me-'what has become of my old friend Green, who kept that shop; I see new people have got it.' Turning suddenly to look at the shop indicated, I was completely dazzled by the bright reflexion of the sun shining on the new brass-plate under the window of the shop, so that for some seconds I could see nothing. As we walked on I soon observed before me in the air the words J. Johnstone & Co.,' in blood-red characters, which soon, however, changed to other colors. With an exclamation of surprise I stated the fact, and we turned back to see whether or not this was really the inscription on the brass-plate, and found that it was. The optical account of this was simple enough. The retina had been partially paralyzed from the intense light reflected from the plate, but as I had turned with pain from it instantly, the part corresponding to the black letters on the plate had escaped, and as I walked on the red strong light reflected from surrounding objects on this part became contracted with the darkness, as yet showing itself on all the surrounding parts of the disordered retina; as the retina recovered its tone other colors in succession took possession of the place which at first had been red. Sir J. Macneill then told me that when first he had gone to reside in London, a murder had been found out by a similar circumstance. The murderer, then unknown, had been dazzled by the reflexion of the sun from a bucket of water, which another man was carrying before him, and soon after seeing in the air what he took for a bucketfull of blood going before him, he was seized with such horror that he declared himself the murderer, and disclosed such facts as brought the crime home to him, so that he was convicted and executed." II. GEOLOGY. 1. A record of Earthquakes, kept at Hilo, Hawaii; by S. C. LYMAN, (from a letter addressed to Dr. C. F. Winslow, and by him communicated for this Journal).-June, 1833. Two slight shocks during the month. Oct. 3, 1833.-Two shocks in the night, one quite heavy. Oct. 13.-A shock at 3 o'clock, P. M., motion quick, up and down. Feb. 19, 1834.-At 6 P. M. there was a slight shaking of the earth which was almost instantaneously followed by a shock so heavy as to upset some things in the house, throw the cream off from milk standing in pans, and throw water out of a pitcher standing in a wash-bowl. At 9 o'clock in the evening there was again a shaking of the earth which lasted only a few seconds. May 14.-A heavy shock between 2 and 3 P. M. Aug. 3.-One at about 4 o'clock, A. M., so heavy as to waken people, and cause them some alarm. March 23, 1835.-One slight shock at 9 A. M. March 26.-Three shocks following each other in quick succession at 25 minutes past 6 o'clock A. M. July 21.-Three shocks during the day. Sept. 6.-One shock at 2 or 3 o'clock A. M. June 20, 1837.-A smart shock at 20 minutes before 7 P. M. Jan. 12, 1838.-A smart shock some time after midnight. Jan. 29.-Three shocks in pretty quick succession a little past 10 o'clock P. M. The first two heavy, the last slight. July 9.-A slight shock between 8 and 9 o'clock A. M. Oct. 16.-A jar merely, accompanied with a noise resembling the discharge of distant cannon. Nov. 5.-Three shocks during the day, one in the forenoon and two in the afternoon. Nov. 6.-One shock, a few minutes before 10 A. M. Nov. 7.-A smart shock at midnight, another at twenty minutes past 3, and another about 4 o'clock A. M. Nov. 8.-Several shocks during the day, and twelve distinct ones duriug the night. There were frequent shocks during the day and night for five days following, and then occasional ones during the month, none of them heavy, some of them accompanied by a rumbling sound, others by a noise like the rushing of water by a ship. There was one quite heavy shock, but I do not recollect the time. Dec. 4:-A distinct though not heavy shock. Dec. 9.-One shock at 40 minutes before 12 at noon. Dec. 10.-One shock at 4 o'clock, A. M. Dec. 12.-A severe shock at 1 o'clock P. M. Stone walls were thrown down, and plastering a good deal cracked, but no other damage done. April 7, 1839.-A pretty smart shock at midday. Feb. 1, 1840.-A severe shock at half past 1 P. M. May 5.-A slight shock at 4 P. M. Oct. 14.-A slight shock between 8 and 9 o'clock P. M. Dec. 18.Two smart shocks about 5 A. M., waking us from our slumbers. March 11, 1841.-Two shocks, one at fifteen minutes before 1, the other at 20 minutes before 2 P. M. The motion was up and down, gentle and easy. April 5.-A smart shock at 15 minutes past 1 P. M., undulations north and south. April 7.-At 11 P. M. This was the most severe shock we have ever felt. Stone walls thrown down, plastering cracked, and chimney also, milk was thrown out of the pans and water out of a pail a little more than half full. Motion undulating north and south. In just one hour there was a trembling of the earth, and after another hour another jar. May 28.-A shock at half past 7 P. M., not heavy. June 26.-A shock in the night. July 3.-A shock between 5 and 6 A. M. Sept. -A smart shock in the night. Nov. 28.-A shock in the night. Feb. 14, 1842.-A shock at 5 o'clock a. M. May 15.-A shock in the night. Aug. 31.-A shock at half past 9 P. M., not heavy. Nov. 9.-A shock in the night so heavy as to awaken us. March 8, 1843.-A shock at 7 o'clock P. M. April 27.-A shock in the night. July -Two shocks during the month. One in the night, or P. M. Dec. 15. A shock at 10 A. M. Feb. 18, 1844.-A severe shock at half past 6 P. M. Sept. 1.-A heavy shock between 7 and 8 A. M. Dec. 21, 1845.-A moderate shock in the night. March 29, 1847.-A shock between 9 and 10 A. M. July 9.-A severe and protracted shock at 4 A. M. |