ton of coals will be 4s. 6d. The works have been made to supply 950,000,000 cubic feet of gas annually, or at the rate of 23 millions of cubic feet daily.

ELECTRICITY.-A thermo-electrical apparatus, with galena and iron, has been made by MM. Mure, Clamond, and Gaiffe. According to the results of their experiments, this apparatus deserves the attention of all who require galvanic batteries, since regularity and steadiness of action are here combined with economy and the absence of inconvenient vapours.

For telegraphic work or domestic purposes, where a constant galvanic current is required with little trouble (electric bells, fire and thief detectors), the writer has found the new battery known as the Leclanché cell to be most perfect in action. The main feature is that peroxide of manganese is used with zinc (not amalgamated) and an aqueous solution of an alkaline salt, chloride of ammonium being preferred. The cells are of three sizes: the smallest, with a porous pot 4 3 inches high, can accomplish an annual electric work which may be represented by 620 grains of copper reduced in the voltameter; the medium size, with a 6-inch porous pot, can reduce from 950 to 1000 grains; while the large size gives a work equal to 1500 or 2000 grains.

F. Zaliwski has described a galvanic element with three fluids. This contrivance consists of two porous cells placed one inside the other, and surrounded by another suitable vessel. The inner vessel contains nitric acid and a piece of carbon, the intermediate vessel contains sulphuric acid, and the outer vessel a solution of sal-ammoniac in water and a piece of zinc. This author states that this arrange

ment is superior to a Bunsen cell.

The phenomena of atmospheric electricity at the island of Haiti, or St. Domingo, as it is also called, are of a very striking character. According to Mr. Ackermann, who has during a series of five years made meteorological observations at Port-au-Prince, there have, on an average, been 129 days of each year either severe thunderstorms or other very marked electrical phenomena, especially during the months of May, July, August, and September. Severe thunderstorms more frequently occur during day than night-time. The year 1868 was especially remarkable for severe thunderstorms; during one of these, lasting for forty-five minutes, 400 lightning flashes were distinctly seen.

A company has been formed in America with the view of coyering other metals, by galvano-plastic means, with a more or less thick coating of pure nickel. Since that metal is very hard, it resists, even in thin layers, rather rough usage; it is not oxidized, even in contact with water, at the ordinary temperature, and the metal as

sumes a brilliant polish if required. The method employed for the deposition of nickel was treated of at a meeting of the French Academy. The company alluded to have established a branch manufactory at Paris, under the management of M. Gaiffe.

M. Gaiffe calls attention to the fact that the presence of even the smallest quantity of potassa, or soda, or alkaline earths in the bath containing the nickelizing preparation is injurious to effect a properly-adhesive coating of the metal. The use of perfectly pure double chloride of nickel and ammonium, or of perfectly pure sulphate of nickel and ammonium, and, moreover, of pure nickel as one of the electrodes, is required. By these means the nickel is made to adhere regularly and strongly, and only requires polishing after the metal, coated over, is taken from the bath. On the other hand, M. Becquerel now states that he has purposely repeated some of his former experiments, with the express view of ascertaining whether the statement made by M. Gaiffe, concerning the injurious action of the presence of potassa, be correct or not. The result of experiments is that the presence of potassa is not at all injurious to, and in no wise affects, the deposition of nickel, since the double sulphate of nickel and potassa can be applied, as well as the double sulphate of nickel and ammonia; but if the positive electrode is not made of nickel, it is necessary to add free ammonia, in order to saturate the sulphuric acid, which is set free.

M. Scoutetten states that the accidental striking of lightning on the house of a vineyard proprietor caused the rupture of several large hogsheads containing wine, which found its way into a cavity existing in the cellar of the house. The owner imagined his wine lost and spoiled, but found, to his astonishment, that the wine, instead of having been deteriorated, had become better than it was before. This accidental occurrence having come to the knowledge of General Marey-Mouge, caused M. Scoutetten to be consulted, and a series of experiments instituted with various kinds of wine, of inferior as well as medium quality. A series of experiments, made on the large scale, and with various sources of electricity, led to the result that electricity, under whatever form applied (whether as a regular current, or a succession of discharges accompanied by sparks), improve wine, rendering it mellow and mature. As to the mode of action of this agent, the author thinks that the bitartrate of potassa present in wine is decomposed, the potassa set free saturates the acids of the wine, and the free tartaric acid, reacting upon the fatty matters present, favours the formation of the ethers which constitute the bouquet of the wine. Moreover a small quantity of water is decomposed, and the oxygen thereof reacts upon some of the constituents of the wine, thereby forming new compounds which are peculiar to old wines.

12. ZOOLOGY-ANIMAL PHYSIOLOGY AND

MORPHOLOGY.

PHYSIOLOGY.

Researches on the Relation of Heat to Work in the Human Body.Professor Pettenkoffer, of Munich, has undertaken an investigation into the amount of heat produced by the human body when at rest and when at work, which promises to give highly important results. The wonderful experimental chamber which King Max had constructed for Pettenkoffer's work is to be made use of. The chamber, which is about 10 feet square, is fitted with an iron tube through which the air is regularly drawn by means of an aspirator worked by a steam-engine, the air being accurately measured in a gas meter. Smaller aspirators bring measured quantities of the air through analysis-tubes in which the quantities of carbonic acid, water, hydrogen and carburetted hydrogens (the last two by combustion with spongy platinum) are determined in the air both before and after it enters the chamber. The small aspirators, bringing a small but constant fraction of the whole air passed into the chamber through the analysis apparatus, the quantities of carbonic acid gas, water and hydrogen in the whole can be readily calculated. It is now intended to take the temperature of the air before and after it traverses the chamber, and in this manner to ascertain the actual amount of heat produced by the human body when at rest and when at work, and in relation to the amounts of the various excretions. For this purpose a smaller chamber has been constructed within the first made, and arrangements adapted by means of non-conductors, &c., to prevent, as far as possible, the loss of heat. It is found that there is a constant loss of about 40 per cent. of the total heat with two candles burnt in the chamber; of about 50 per cent. with four. The heating effect upon the air passed through the apparatus is determined before each experiment with stearine candles of known weight, and thus when a man is placed in the chamber instead of the candles, you get his heating effect in terms of stearine candles, and this is, of course, at once convertible into units of heat. The preliminary experiments with candles promise very accurate and satisfactory results from this method. As an apparatus for chemical analysis the chamber is perfect; so perfect that the percentage composition of a candle can be determined as accurately by burning it in the chamber, and the fractional analysis, as by the most complete direct combustions. The determination of the heat produced is a matter of more difficulty on account of the fluctuations of external temperature and the delicacy of the thermometers which must be used; but Professor Pettenkoffer has used every precaution, and succeeded in rendering the apparatus efficient. The experiments are now in

progress; a man is to be kept in the chamber for six to eight hours, and the work done is in the form of crank-turning.

The Absence of Currents in Uninjured Inactive Muscle.-Professor Hermann states that if the gastrocnemius muscle of the frog be so prepared for investigation that no contact between the cutaneous secretion and the surface of the muscle takes place, then, with an exceedingly delicate galvanometer, only the very smallest deflection of the needle is obtained. He concludes, therefore, that by still greater care muscles can be obtained perfectly free from currents, and regards previous observations of muscular currents as having a very different significance to what has been supposed, being really artificial phenomena due to certain accidents of manipulation.

Pasteur's Views on Fermentation.-Professor Liebig disputes Pasteur's theory that the decomposition of sugar in fermentation depends on the development and multiplication of yeast-cells, and that fermentation is only a phenomenon accompanying the vital processes of the yeast. Liebig considers that Pasteur's researches have not explained fermentation, but have only made known another phenomenon the development of yeast-which equally requires explanation.

Physiology of Sepia.-A series of interesting experiments have been made by M. Bert on this subject. He finds that the excision of the large supra-oesophageal ganglion-mass causes no pain or inconvenience to the animal, but simply deprives it of voluntary motion. He hence infers it to be equivalent to the vertebrate cerebrum. The contents of the salivary glands, as also of the liver and pancreas (so-called), are acid. The peritoneal coeca excrete uric acid. Strychnia and curare have the same effect on this animal as on vertebrates.

MORPHOLOGY.

Commensalism.-Professor Van Beneden, in an interesting address to the Belgian Academy of Sciences, proposes this word to distinguish a group of animals hitherto confused with what he would term veritable parasites. Commensal parasites, or commensals, do not feed on the animal with which they are found, but by it: they are not destructive or injurious to their hosts, but often are of service, if we may judge from the constancy of association and the satisfaction which both parties seem to enjoy. Professor Van Beneden distinguishes fixed and free commensals. Among the fixed we may mention the various barnacles which are attached to whales and seaturtles; the Anemone parasitica, which invariably is fixed to a shell inhabited by a particular species of Hermit-crab, said to exhibit great affection for the polyp it bears on its back; many Polyzoa and Hydrozoa, which attach themselves to the carapaces of crustacea, especially the hairy-looking Dromia of our southern coasts.

Free commensals are the most numerous. Little fish live inside jelly fishes, without incommoding their host, or being incommoded; a whole troop of a particular species may be thus sometimes seen. Similarly a fish called Fierasfer lives inside a Holothurian, and in a large species of Anemone the same observation has been made. Dr. Semper has described, in addition to the little fish inhabiting Holothuriæ, several molluscs, which also live in this way; whilst Müller made known Entoconchon, from the Synapta; and Stylifer lives on Echinus. The Remora is a remarkable instance of commensalism. This strange fish, by means of the sucker on the back of its head, attaches itself to other fish and to whales, sometimes to ships, and is thus carried along through rich feeding-grounds. The inhabitants of Mozambique use this fish as a means of capturing others, tying a string to it and letting it out into the sea, when it attaches itself to some unsuspecting inhabitant of the ocean, which, together with the Remora, is speedily dragged to shore. The little crustacean (Pinnotheres), which lives inside the shell of the common edible mussel, has long been known, and various species in this and other countries have excited speculation and fable. There is no doubt a most cordial understanding between the little crab and its host; and though we cannot go so far as to believe that the crustacean acts as a watchman for the Mytilus, warning it when to close its shell, it is yet very evident that there is a close relationship of reciprocal advantage existing between the two. Chatogaster, the little worm which crawls about on Lymnæus and Planorbis-the common water-snails of our ponds-is a good example of a commensal, sticking very close to his friend, feeding on the Cercaria (true parasites) and other matters which accumulate on the snail's body. Many tubicolous Annelids have a commensal, or messmate, who shares their residence; such are many scale-bearing Annelids -the Polynöina, which ensconce themselves in the tubes of Chatopterus insignis, of Terebella nebulosa, and others. One Polynöe was many years since described by Professor Huxley as living on the common Cross-star, and hence named P. astericola.

The distinction between commensal and parasite is this, that the parasite uses his host for food; whilst the animals which are mentioned above, and many others enumerated by Professor Van Beneden, though often termed parasitic, do not feed upon the tissues of the animal with which they live, and hence have a very different relation to them. Their food consists often of what is rejected by, or is even hurtful to, their hosts; and though the line between them and true parasites may not be easy to draw sharply, it is yet useful to recognize them under a distinct name, as proposed by Professor Van Beneden.

A New Genus of Cervidæ.—Mr. R. Swinhoe, who, as consul at Formosa and various stations on the Chinese coast, has done most