charcoal at hand, the jeweller took coal for heating the muffle for enamelling, an operation which succeeded most perfectly; but on taking the buttons from the muffle, the jewels had become perfectly black, and no amount of rubbing or friction restored them to their pristine state. The jeweller was therefore obliged to dismount the jewels, which looked like plumbago, and to send them to Paris, when by the first touch of the lapidary's wheel they became restored to their former beauty; while, curiously enough, their weight had not changed. Professor Morren who, through the kindness of MM. Laurin, jewellers at Marseilles, was enabled to experiment with several diamonds, placed them on a small platinum boat in a platinum tube, and tried the effect of a high temperature simultaneously with different gases. Heated in coal-gas the gems become blackish, increase in weight, and are found to be coated with a stronglyadhesive layer of carbon, such as is deposited in gas retorts; in pure hydrogen, the gems may be heated almost to the meltingpoint of platinum without undergoing any change; heated in carbonic acid gas, the gems become dull and lose a little weight. The carbonic acid gas was found to be dissociated into carbonic oxide and carbonic acid; this, the author found, was caused by the platinum and not by the diamond. When the diamond is placed in oxygen gas and ignited, it continues to burn, but remains white, appearing as a piece of unpolished glass; the stone does not blacken, nor swell up, and, if it is free from flaws or cracks, does not split asunder. Dr. Janssen, who, it will be remembered, went to India for the purpose of observing the total solar eclipse, has communicated some observations on the artificial production of ice in India. In many parts of the Indian continent, the natives dig shallow pits in localities which are freely open to the sky and distant from trees. The pits are lined with straw, and upon the straw are placed dishes (male of a very porous earthenware) filled with water. During the calm and clear nights prevailing in the period from November to the end of February the water placed in the dishes freezes, yielding a solid cake of ice, while the temperature of the air is + 10°. Dr. Janssen has investigated this curious subject experimentally, and has found that the freezing is principally due to the radiation during the night; but the evaporation of the water, aided by the porosity of the earthenware employed, is at the same time not to be overlooked. In order to exhibit the effect of the expansion of water when freezing, F. Rüdorff fills with distilled and previously well-boiled and cooled water a cast-iron cylinder, having the following dimensions:-Height, 160 millimètres ; diameter (external), 50 millimètres; thickness of solid iron, 15 millimètres. After having been filled with water this apparatus is closed by means of a plug screwed into the neck, and the cylinder is next placed in a mixture of three parts VOL. VII. 2 G of snow or pounded ice, and one part of common salt; after about forty minutes the cylinder bursts with a loud report. It is essential for the success of this experiment that the plug fits very perfectly, and that the cylinder, after having been filled with water, be placed for some time in ice. The wooden pail which contains the freezing mixture should be roomy, and be covered with a stout towel to prevent the spirting about of the contents at the time of the bursting. Some experiments on the freezing of wine have been tried by A. Rousselle. The reason why freezing improves wines, under certain conditions, is, according to this author, because by partial freezing the proportion of all the fixed substances in the liquid wine is increased; and these are, moreover, thereby rendered more fit for causing the combination of the acids with the alcohol, so as to form those ethers to which wine owes its peculiarly distinct flavour, aroma, and strength. Dr. Hann has tried to solve by observation the problem of the decrease of the temperature of the air in relation to the elevation above sea-level, by comparing the average of temperature as observed at certain groups of stations situated under the same mean latitude and longitude, and by taking into account local influences. Seven of these groups are situated in the western portion of the Alps, at from 230 to 3330 mètres above sea-level; four in the northern part of Switzerland, at from 500 to 1780 mètres above sea-level; three in the Rauhe Alps (Wurtemburg), at from 310 to 810 mètres above sea-level; four in the Erzgebirge (Central Germany), at from 180 to 850 mètres above sea-level; and four in the Harz (province of Hanover and Brunswick), at from 70 to 1140 mètres above sealevel. The results obtained have proved that, in the instances mentioned, the decrease of the temperature of the atmosphere near the ground is really proportionate to the height of the locality above sea-level. When the results of all the observations are duly considered, there is discovered a strongly marked annual periodicity, and a very uniform decrease of temperature from below to above, the average relation of the temperature reigning in December being, to that of June, as 1 to 2. Dr. Von Wartha has obtained solid disulphide of carbon by the rapid evaporation of this liquid itself, in the same way as solid carbonic acid is formed. The solid sulphide melts at 9° F., and has the appearance of small cauliflowers. Some time ago M. Lamy proposed a pyrometer based upon the dissociation of carbonate of lime. He now proposes to apply ammoniacal chloride of calcium, which gives off ammonia at low temperatures. The instrument is to be connected with a manometer, which will record the temperature. The contrivance is to be especially adapted to record the temperature at different depths under the surface of the soil. In reference to this, M. E. Becquerel and others have very properly observed that better and far more accurate means for accomplishing this purpose exist already, and are daily employed with success. A valuable substance for crucibles and fire-bricks has recently been discovered. There occurs, in the Département des Ardennes, France, a variety of hydrated silica known by the name of gaize, and geologically situated below the cretaceous deposit; the thickness of this layer is 30 mètres, and it extends over a distance of 24-85 English miles. The sp. gr. of this substance is 1.48 in crude state, and after ignition 1:44. This stone is used as a building stone; it is, at first, quite soft, so that it can be cut with a knife. The material resists a very high temperature without fusion or cracking, or, also, of perceptible contraction, either cubical or linear, and it has consequently been recommended for the manufacture of crucibles (on the lathe), for fire-bricks, and for furnaces. ELECTRICITY. A cause of error in electroscopic experiments has been pointed out by Sir Charles Wheatstone, F.R.S. In the course of some experiments on electrical conduction and induction the author was frequently delayed by what at first appeared to be very puzzling results. Occasionally he found that he could not discharge the electrometer with the finger (or only to a certain degree), and that it was necessary, before commencing another experiment, to be in communication with a gas-pipe which entered the room. How he became charged could not at that time be explained; observation and experiment, however, soon led Sir Charles to the true solution. He was sitting at a table not far from the fire-place, with the electrometer (one of Peltier's construction) before him, and was engaged in experimenting with discs of various substances. To ensure that the one in hand (which was of tortoiseshell) should be perfectly dry, it was held for a minute before the fire. Returning, and placing it on the plate of the electrometer, it had apparently acquired a strong charge, deflecting the index of the electrometer beyond 90°, and it was then observed that the same thing took place with every disc thus presented to the fire, whether of metal or any other substance. The first impression was that the disc had been rendered electrical by heat; but, on placing it in contact with a vessel of boiling water, or heating it by a gas-lamp, no such effect was produced. The next conjecture was that the phenomenon might arise from a difference in the electrical state of the air in the room, and that at the top of the chimney. That this conjecture, however, was not tenable was soon evident, because the same deviation of the needle of the electrometer was produced by bringing the disc near any part of the wall of the room. This seemed to indicate that different parts of the room were in different electrical states; but this, again, was dis proved by finding that, when the positions of the electrometer and the place where the disc was supposed to be charged were interchanged, the charge of the electrometer was still always negative. The last resource was to assume that the author himself had become charged by walking across the carpeted room, though the effect was produced even by the most careful treading. This ultimately proved to be the case; for, resuming his seat at the table, and scraping the foot on the rug, Sir Charles was able, at will, to move the index to its greatest extent. As a substitute for copper for the Daniell Electric Battery, Dr. C. Stölzel proposes to take a piece of well-polished tin plate (sheet tin, not tinned iron), immerse it in a very dilute solution of a copper salt, and put it in connection with a weak galvanic current. After the lapse of from fifteen to eighteen hours a layer of strongly adhering metallic copper will have become firmly deposited upon the tin plate; and the latter, after having been bent into the required shape, is an excellent, cheap, and durable substitute for the copper cylinder in Daniell's battery. Considering the numerous experiments now being tried on wine, it is to be hoped that the quality of the cheaper kinds of this beverage will shortly show some improvement. Whilst Dr. Rousselle proposes to freeze wine, Dr. Scontettin prefers to electrify it. As a very tangible proof of the gain obtained by the immediate conversion of young wines into drinkable beverages by means of electricity, the author states that, considering that the annual production of wine of France amounts to from 60 to 70 millions of hectolitres (each equal to rather more than 22 gallons), and that at least 10 francs per hectolitre is lost by vaporization during the time of the maturity of the wine while in casks, this represents an amount of from 600 to 700 millions of francs gained by rendering wine fit for immediate consumption by the author's electric process. We may not inaptly apply here, "Si non e vero e bene trovato." Some useful electrolytic experiments have been tried by P. Burckhard. After describing his arrangement, the author states that oxide of bismuth is not a conductor of electricity unless it be in a state of fusion, but in that case one of the copper electrodes becomes coated with bismuth; while, if platinum electrodes are used, there is formed at one of the electrodes a very fusible alloy of the two metals. Fused borax is not a bad conductor, although the author confirmed the statement made by Dr. Tichanowitsch that pure boric acid does not conduct electricity at all. When borax in a fused state is experimented with, a series of compounds are formed or volatilized; but the main result is its decomposition into soda, oxygen, and boron. Pyrophosphate of soda in a fused state yields, among the products of electrolysis, phosphide of platinum, if a platinum electrode be applied; but the decomposition, which is chiefly the result of the electrolysis of this salt, is its splitting up into oxygen, phosphorus, and soda. Carbonate of soda in a fused state is a good conductor of electricity; it is decomposed into carbonic acid and soda, but a small portion of carbon is also formed. A series of very accurate experiments, made with chemically pure substances, have been tried by M. E. Becquerel, on the electromotive force of divers substances, as for instance, pure carbon, gold, platinum, &c., in the presence of water and other fluids. Among the curious facts elicited is this, that pure gold, obtained from the French Mint, is acted upon by pure water in a manner not hitherto explained, but which gives the author occasion to ask whether possibly gold does not contain another substance which has not been discovered, or whether perhaps the slow action of the water is not the cause of the disaggregation of the gold, thus explaining the fact of its being found in rivers in the state of dust. In a very lengthy paper on the properties of galvanically-precipitated iron, R. Lenz records a series of experiments, not only made with iron, but also with copper. The results are stated as follows:Iron and copper, when reduced to the metallic state by electricity, contain gases occluded, among which hydrogen is in largest amount: the bulk of gas thus occluded varies considerably, but iron has been found by the author to occlude as much as 185 times its own bulk. The absorption of the gases is more considerable in the first layers of metal deposited. On being heated, the iron loses gas, even below 100°, the gas evolved at so low a temperature being chiefly hydrogen. Iron which has been galvanically precipitated, and then made red-hot and cooled, becomes oxidized when put into water, that liquid being decomposed and hydrogen given off. 12. ZOOLOGY-ANIMAL MORPHOLOGY AND PHYSIOLOGY. MORPHOLOGY. A new Ganoid Fish from Australia.-We have this quarter to record what is certainly the most important zoological acquisition which science has received since the finding of the Archæopteryx of Solenhofen. Mr. Gerard Kreft, the able curator of the Australian Museum of Sydney, who has already by his single exertions shown us what a rich mine of new forms is still waiting to be brought to the hands of science in the Australian continent, has sent over photographs of a fish obtained in the rivers of Eastern Queens |