IN the same journal M. de la Source describes his experiments on the dialysis of ferric oxide dissolved in a solution of ferric chloride. "Fer Bravais of medicine consists of 30Fe2O3. FeCl6; after three months' dialysis of a dilute solution of this substance the greater part of the chlorine had passed into the dyalysate, the proportion of ferric oxide to chloride was then 116FeO. Fe,Cl, and the chlorine yet continued to pass through the dialyser. The author thinks that ferric hydrate is, per se, under certain conditions soluble in water.

HERR A. HERZEN describes in Bied. Centralblatt some experiments on acetous fermentation. In each of three flasks was placed 100 c.c. pure water: to the first flask 10 per cent. pure alcohol and a drop from the surface of a fermenting wine full of Mycoderma aceti were added; to the second flask were added 5 per cent. of pure acetic acid and a drop of the fermenting wine; and to the third flask were added 5 per cent. acetic acid, 5 per cent. of a saturated solution of boric acid, and a drop of the fermenting wine. After eight days at 25° no Mycoderma appeared in the first flask, much appeared in the second, and a little in the third. Hence the author concludes that Mycoderma aceti lives at the expense of acetic acid already formed in wine, and that it does not cause the transformation of alcohol into acetic acid, but that it is rather a consequence of this chemical change; further, that boric acid retards the development of Mycoderma, but does not prevent it in presence of already-formed acetic acid.

IN Dingler's Polytech-Journal a paper appears by Drs. Lunge and Schäppi, on bleaching-powder. The results confirm the now generally accepted formula first proposed by Odling, viz., CaOČICI.

It was shown some time ago by H. T. Brown that alcoholic fermentation proceeds more slowly under diminished than under ordinary pressure. According to Boussingault (Compt. rend.), however, sugar is rapidly transformed into alcohol by the action of yeast, if the carbon dioxide and alcohol, as these are produced, be rapidly removed from the fermenting liquid. Addition of alcohol soon stops fermentation under ordinary circumstances; Boussingault shows that if the vessel containing the fermenting liquid be connected with an air-pump which is worked energetically, fermentation proceeds rapidly even when a considerable amount of alcohol has been added to the liquid.

IN connection with the recent liquefaction of ozone by Hautefeuille and Chappuis, the following numbers, from a paper by the same authors in Compt. rend., are of interest, as showing the exact influence of temperature and pressure on the ozonising of oxygen. Diminution of pressure does not tend to increase the amount of ozone produced, but decreased temperature exerts a marked action in increasing the amount of oxygen transformed into ozone :

Tension of Oxygen. -23°

760

108 70

380

5163

300

40 20

225 180

24.80

Tension of ozone.

Proportion of ozone by weight 20°. 100°. -23. 20°. 100°. 82 84 53'96 O'214 O'149 0'106 38776 31754 1'48 0'204 0'152 0'123 0'0117 30*60 22'20 O'201 0'1525 O'112 22'95 15°52 0*038 O'191 0'153 O'104 0'0118 22 30 16:53 10°52 0'181 0'137 0089 A. DITTE describes in Compt. rend. a number of new fluorine compounds of uranium; the most important are UF. SHF and UO,F2, produced by the action of hydrofluoric acid on the oxide U308 when the former compound is heated in a closed platinum dish it melts, gives off hydrofluoric acid and small quantities of the oxyfluoride UOF, which compound is produced in larger quantity by heating the above-mentioned oxyfluoride, UOF, in a closed vessel. The hexfluoride UF, is produced by heating the double salt UF. 8HF in an open crucible. Various double salts are also described, the general formula bing UO,F2. 4MF, where M may be K, Na, Li, Rb, or Tl.

CLEVE has made a redetermination of the atomic weight of the very rare metal erbium (Compt. rend.). Assuming the formula of the oxide to be Er,O,, the atomic weight of the metal is 166. Pure erbia, Er,O, is a beautiful rose-coloured earth, slowly soluble in acids, having a specific gravity of 8'64, and forming salts characterised by a deep-red colour; several of these salts are described by Cleve.

THE same author has succeeded in separating nearly pure thulium; this metal and its salts are colourless, but solutions of the salts show two absorption bands, one strongly marked in the

red, and one broad band in the blue. The atomic weight of thulium is 1296 or 1707, according as the metal is regarded as di- or tri-valent.

PHYSICAL NOTES

Ir is stated that amongst the recent discoveries of Prof. Bell in connection with the photophone research is the interesting fact that melted sulphur conducts electrically like selenium, but only at temperatures below that at which it thickens and becomes dark and viscid.

THE Comptes rendus for November 2 informs us that Prof. Graham Bell and M. Janssen have attempted to hear with the photophone the sounds believed to accompany the rapid commotions taking place in the solar photosphere. The experiments were made at the Observatory of Meudon, a selenium cylinder being placed in different parts of an image of the sun some two feet in diameter. No very conclusive results were obtained, but M. Janssen has further suggested that a sort of concentrated effect might be obtained by passing a number of successive photographs of a sun-spot across a beam of light, the variations of the intensity of the beam producing sounds when they fall upon the sensitive "photophonic pile" of selenium. Some experiments in furtherance of this suggestion are now proceeding.

HAVING undertaken a series of researches upon the rapidity of evaporation of liquids, in dependence from the cohesion of molecules on their surfaces, M. Sreznevsky has measured how this rapidity varies with the variations of the height of the meniscus. He has established that, the diameter of the meniscus remaining invariable, the rapidity of evaporation increases as the height of the meniscus diminishes, that is, as its radius increases. There is however an anomaly as to this last law for distilled water: when the evaporation is measured in a meniscus the height of which is greater than the radius of its basis, the rapidity of evaporation increases throughout, however the radius of the meniscus begins by diminishing, and increases only after having passed through a minimum, but this minimum does not have a corresponding minimum in the rapidity of evaporation.

AT the recent meeting of the Helvetic Society of Natural Sciences M. Forel described a thermal bar which is developed in winter parallel to the shore of a lake of fresh water, and which separates the pelagic from the littoral region. The water of the former region remains long, and in some lakes always, at a temperature above 4° C. ; in the littoral region, if the winter be cold, the temperature descends between 4° and zero; and between the two there is a band of water at 4°, descending to the bottom -a kind of mountain with crest parallel to the shore and a talus on either side.

M. DUFOUR described at the same meeting an apparatus for indicating the variations of chemical intensity of the sunlight. It has some likeness to Draper's tithonometer; the principle is, opposing the variable action of light on a mixture of chlorine and hydrogen, with an electric current (of variable intensity, and measurable each instant), which by its passage causes decomposition of a quantity of hydrochloric acid equal to that produced by action of the light on the mixture of chlorine and hydrogen. The apparatus is like a Rumford differential thermometer; in trodes, in the other some sulphuric acid. The light acts on the one bulb is some hydrochloric acid solution, with carbon elec

former. One mode of measurement is to note the time taken in

displacement of the sulphuric acid column a certain distance along the connecting tube. Then bring back the column to its original position by passing the current.

M. PICTET has lately made experiments (Arch. de Sci.) as to the dissolving power of gases and vapours on one another. Various solutions of alcohol and water were successively put into one of two glass balloons connected by a tube; pressure was diminished with an air-pump, so that the space became filled with vapours from the mixture. By closing the tapered point of the second balloon with the blowpipe, the apparatus allowed of distillation being effected with small differences of temperature. Plunging successively the balloon that held the solution in water at from o° to 80°, and the other in water only 1° or a fraction of a degree below that of the liquid, M. Pictet got condensed products, the quality of which indicated what "affinity of solution" existed between water and alcohol. The following conclusions were arrived at: The weight of condensed liquid is proportional, in unit time, to

the difference of temperature between the liquid in ebullition and the condensed liquid. The weight of liquid condensed in unit time is independent of the interior pressure or of the mean temperature during distillation. Analysis shows that the gases have no power of solution on one another. M. Pictet was thus led to an industrial process for rectification of spirits.

GEOGRAPHICAL NOTES

AT the meeting of the Geographical Society on Monday, Sir Bartle Frere read what may best be described as a suggestive paper on Temperate South Africa as a route to the Central Equatorial Region. After defining the temperate region as the vast tract of country extending to Cape Frio on the Atlantic coast and to the mouth of the Kiver Tugela on the opposite side of the continent, and giving a brief account of its geography, &c., Sir Bartle addressed himself chiefly to the task of pointing out how it could be made available as a base of operations in exploring the country north of the Zambesi, and suggesting agencies which might be turned to account for the extension of geographical knowledge. These agencies are the traders and hunters, who have a wide acquaintance with many regions otherwise unknown, and missionaries of various denominations. The latter have no less than eighty-four fixed stations beyond the colonial boundaries, manned by 812 Europeans, many of whom are highlycultivated and intelligent men, and have great opportunities for acquiring geographical information. Sir Bartle Frere also hoped that the Council of the Society might see their way to urging the Government to undertake a proper survey of the coast-line, as well as of the interior of the five colonies.

AT the meeting of the Berlin Geographical Society on November 6 the safe arrival of Dr. Lenz at Timbuctoo (by a route not before taken by any European) was announced. Two of his followers were lost in the desert, and two had gone back. Dr. Stecker (who lately went to Massowah with Herr Rohlfs) will, according to circumstances, either push through the Galla regions or to the East coast, or to the Great Lakes. Major v. Mechow reached a town on the Quanza, in the territory of the Hollo, about 2c0 km. from Malange on July 19, after great difficulties, especially in carriage of the boat. The natives were friendly throughout. A little above the place reached are the two last falls of the Quanza, between which is the mouth of the Cambo. The Major seems to have been the first white to visit these waterfalls. He was going to Löpung with a view to determine the course of the Quanza. Dr. Pogge and Lieut. Wissmann were also travelling in that region the same month, intending to reach Mussumba, the residence of the Muata Jambo; Dr. Pogge's object is to establish stations in the interior. Lieut. Wissmann will make journeys for topographical and collecting purposes. The Italian traveller, Dr. Matteucci, is seeking to reach Bomu from South Dar-For, going round Wadai and Bagirmi. Inter alia the Society resolved to memo. rialise the German Government to take part in the international project of systematic Polar investigation.

AT the sitting of November 19 of the Société de Géographie of Paris M. Zweifel received the palm of Officer of the Academy as a reward for the discovery of the sources of the Niger, in company with M. Marius Moustier. The laureate declining to speak himself, an address was delivered on behalf of him and his companions by Dr. Harmand, the well-known explorer of Cochin China.

It appears that MM. Zweifel and Moustier saw

a granite rock from which the pow.rful stream takes its rise;

studies in Upper Albania. A very fine map embodies the important results of Severzov's exploration of the Pamir in 1878, with accompanying text, followed by an account of Lieut.-Col. Pjevzov's journey through Mongolia in 1878-9, to Kuku-Choto and Kalgan. A summary is given of the Arctic work of 1880, followed by the usual monthly notes.

THE first Bulletin of the recently-formed International Geographical Institute at Berne consists of a programme of the projected Italian Antarctic Expedition under Lieut. Bone, which is to leave Genoa in March 1881. A sketch is given of what has been previously done in this region, showing that the field is practically virgin so far as scientific work is concerned. The programme of the Italian expedition is very comprehensive, and the ultimate object is to pave the way for the establishment of an Antarctic observing station.

No. 3 of vol. iii. of the Deutsche geographische Blätter, the organ of the Bremen Geographical Society, contains the continuation of the unfortunate Dr. Rutenberg's journal in Madagascar, and the lecture given at the Danzig meeting of the German Association by Dr. Neumayer on "Polar Expeditions or Polar Research?" To the latter able lecture we referred last week, the point insisted on being that while the two are perfectly congruous, the former should be subjected to the latter, which must be carried out on the system of Polar observatories advocated by Weyprecht, and to which nearly every civilised nation adheres except England.

THE new number of the Marseilles Geographical Society's Bulletin contains a very voluminous account by Messrs. Zweifel and Moustier, of their expedition to the sources of the Niger. This memoir is illustrated by a map showing their route, and supplemented by an appendix containing information as to the natural resources of the country traversed, the races of the interior, &c.

THE last part of Le Globe contains a paper (with map) on the Island of Cyprus, by M. Paul Chaix, and some account of recent researches in the Pamir, furnished by M. Veniukoff.

IN the current number of Les Missions Catholiques, M. Armbruster has commenced a series of papers on Corea, drawn from information furnished from time to time by the Romish missionaries, the only Europeans who have ever had any opportunity of acquiring a real knowledge of the interior.

priest of Tembi Saleh, who inhabits an island situated on a small lake formed by the stream at a very few miles from its source. So something more remains to be done to complete the work begun by Laing, Reade, and Blyden.

SIR ALLEN YOUNG leaves England next month in his yacht, and will visit, among other places, the Canary Islands, a portion of the West Coast of Africa, and St. Helena, extending his voyage as far as the Cape, where he will make preparations and inquiries for a projected expedition of discovery to be undertaken by him to the Antarctic regions. It will be remembered that the Erebus and Terror, commanded by Sir J. Ross and Capt. Crozier, penetrated in 1841 to 78° 4' S., a latitude which has never been reached before or since.

THE November number of Petermann's Mittheilungen has a long paper by Spiridion Gopcevic, containing his ethnographical

venient length-is to be filled with the substance in a state of the greatest purity possible. It is to contain such a quantity of the substance that, at ordinary atmospheric temperatures, about 3 or 4 centimetres of the tube are occupied by steam of upright position, with convenient appliances for warming the the substance, and the remainder liquid. Fix the tube in an upper 10 centimetres of the length to the critical temperature, or to whatever higher or lower temperature may be desired; and for warming a length of 40 centimetres from the bottom to some lower temperature, and varying its temperature conveniently at pleasure.

Commence by warming the upper part until the surface of separation of liquid and steam sinks below 5 centimetres from the top. Then warm the lowest part until the surface rises By Sir William Thomson, British Association, Swansea, Section A. Tuesday, August 31.

again to a convenient position. Operate thus, keeping the surface of separation of liquid and solid at as nearly as possible a constant position of 3 centimetres below the top of the tube, until the surface of separation disappears.

The temperature of the tube at the place where the surface of separation was seen immediately before disappearance is the critical temperature.

It may be remarked that the changes of bulk produced by the screw and mercury in Andrews' apparatus are, in the method now described, produced by elevations and depressions of temperature in the lower thermal vessel. By proper arrangements these elevations and depressions of temperature may be made as easily, and in some cases as rapidly, as by the turning of a screw. The dispensing with all mechanism and joints, and the simplicity afforded by using the substance to be experimented upon, and no other substance in contact with it, in a hermetically sealed glass vessel, are advantages in the method now described. It is also interesting to remark that in this method we have continuity through the fluid itself all at one equal pressure exceeding the critical pressure, but at different temperatures in different parts, varying continuously from something above the critical tempera ture at the top of the tube to a temperature below the critical temperature in the lower part of the tube.

The pressure may actually be measured by a proper appliance on the outside of the lower part of the tube to measure its augmentation of volume under applied pressure. If this is to be done, the lower thermal vessel must be applied, not round the bottom of the tube, but round the middle portion of it, leaving, as already described, 10 or 20 cms. above for observation of the surface of separation between liquid and vapour, and leaving at the bottom of the tube 20 or 30 cms. for the pressure-measuring appliance.

This appliance would be on the same general principle as that adopted by Prof. Tait in his tests of the Challenger thermome ters under great pressure (Proceedings, Royal Soc. Edin., 1880); a principle which I have myself used in a form of depth-gauge for deep-sea soundings; in which the pressure is measured, not by the compression of air, but by the flexure or other strain produced in brass or glass or other elastic solid.

IN the first part of his work on the Meteorology of the Bombay Presidency, which was submitted to Government in August, 1875, Mr. Charles Chambers pointed out that the variation of the yearly mean barometric pressure at Bombay shows a periodicity nearly corresponding in duration with the decennial sun-spot period (see "Meteorology of the Bombay Presidency," § 26, p. 12), and in August, 1878, in a letter to NATURE, vol. xviii. p. 567, I drew special attention to this relation, pointing out that the observations of the winter and summer half-years, separately as well as conjointly, show that the pressure is low when the sunspot area is great, and vice versa, but that the pressure curve lags behind the sun-spot curve.

In November of the same year the eminent physicist, the late Mr. John Allan Broun, regarding the relation thus established between the variations of barometric pressure and sun-spots as one of very great importance, in that it gave a probability to the existence of similar laws in the variations of other meteorological elements which he believed was previously wanting, communicated to the same periodical (NATURE, vol. xix. p. 6) an article in which he showed, from the observations recorded at Singa. pore, Trevandrum, Madras, and Bombay, that the years of greatest and least mean barometric pressure are probably the same for all India, and from this he inferred that the relation to the decennial sun-spot period found for Bombay holds for all India.

In December, 1878, Mr. S. A. Hill supplemented and confirmed Mr. Broun's communication by giving similar data for Calcutta (NATURE, vol. xix. p. 432).

In May, 1879, Mr. E. D. Archibald communicated to NATURE, vol. xx. p. 28, the fact (brought to his notice by Mr. S. A. Hill) that at St. Petersburg the mean annual barometric pressure is high when the sun-spots are numerous, low when they are few, but that the pressure epochs lag behind the sun-spot epochs.

In December of the same year Mr. Blanford presented to the Asiatic Society of Bengal a paper (Journal of the Asiatic Society of Bengal, vol. xlix. part ii. 1880, p. 70) in which it was shown that the barometric observations recorded at Batavia from 1866 to 1878, at Akyab, Chittagong, and Darjeeling from 1867 to 1878, at Port Blair from 1868 to 1878, and at Singapore from 1869 to 1878, afford more or less confirmation of the results previously obtained for other stations in India. And in the same paper Mr. Blanford brought forward the observations recorded at the Russian observatories at Ekaterinburg, Slatoust, Bogolowsk, and Barnaul from 1847 to 1877, and showed that at the two former stations during the whole period, and at the two latter during the first half of it, the barometric variations were similar to those previously obtained by Mr. Hill for St. Petersburg.

In a subsequent letter to NATURE, published in March, 1880, Mr. Blanford discussed the same observations in greater detail, dealing with the summer and winter observations separately, as well as conjointly, and showed that the decennial variation of the barometric pressure found for St. Petersburg was exhibited only by the observations of the winter months. He also obtained similar results for Ekaterinburg and Barnaul, but he appears to have overlooked the very important facts that the range of the winter curves rapidly decreases in passing from St. Petersburg, through Ekaterinburg to Barnauland, that the summer curves for the two latter stations are, on the whole, of the same character as the summer curves of the Indian stations, as may be seen by comparing the dotted curves for Ekaterinburg and Barnaul, given in NATURE, vol. xxi. p. 48, with the summer curve for Bombay, given in vol. xviii. p. 568 of the same periodical. He also showed that the barometric curves for Batavia, Singapore, and Port Blair were, as at other Indian stations, of the same character both in winter and summer.

In 1873 and 1874 (see British Association Reports for those years) Mr. Meldrum showed that there was strong evidence of a connection between sun-spots and rainfall, and he has recently (see Monthly Notice of the Meteorological Society of Mauritius for December 1878) put this question beyond all reasonable doubt by showing that the mean yearly rainfall of Great Britain, the continent of Europe, America, India, and the Southern Hemisphere, varies in the same way as the sun-spots, being on the average great when they are numerous, small when they are few.

In my "Brief Sketch of the Meteorology of the Bombay Presidency "2 in 1876, I pointed out that the abnormal variations of the monthly mean barometric pressure in that year were mainly variations in the intensity of the usual seasonal movements, although at least some portion of the variations influenced a wider area than the Indian monsoon region, and in the Sketch for 1877 I attributed the uniformly high barometric pressure and the deficient rainfall of that year to a weak development of the equatorial belt of minimum pressure, probably induced by a

diminution of the solar heat.

In the Report on the Meteorology of India in 1877 Mr. Eliot showed that the high pressure of that year was a characteristic of the whole Indian area and also of Australia.

In my meteorological sketch for 1878 I showed that the abnormal barometric movements observed at Zi-ka-wei in China and at Manilla in 1878 were similar to those recorded in Western India; that the latter largely influenced the rainfall of the Bombay Presidency; and that in former years of deficient rainfall at Bombay the barometer had been relatively high, not only at Bombay, but also at Mauritius and Batavia.

In the paper (Journal of the Asiatic Society of Bengal, vol. xlix. part ii., 1880, p. 70) already quoted, Mr. Blanford has confirmed the fact that the excessive pressure observed in the Indian area in the years 1876 to 1878 extended to China and Australia, and he has also shown that it affected Western Siberia also.

In my sketch for the year 1879 I have shown that these uniform variations of barometric pressure are accompanied by a nearly uniform variation of the percentage rainfall of all portions

During the first half of these periods the results for Singapore, Akyab, Chittagong, and Darjeeling differ so much from each other and from the remarkably accordant results obtained from the more widely separated stations of Bombay, Calcutta, Port Blair, and Batavia as to suggest that the former are of doubtful validity during the earlier years.

2 These sketches are submitted annually to Government in August of the year following that to which they refer. See notices in NATURE, vol. xviii. pp. 199 and 619, vol. xxi. p. 384. The sketch for 1879, containing some further important conclusions with reference to the variations of rainfall and barometric pressure, has recently been submitted to Government.

of the Bombay Presidency, and that the proportionate increase or decrease of the abnormal rainfall, corresponding to a fall or rise in the abnormal pressure of a tenth of an inch of mercury, amounts to more than one hundred per cent. of the normall fall; but that the variations of the ordinary monsoon gradients produce very different effects on the rainfall of different districts, depending on the geographical peculiarities of the particular locality.

From all these facts it is clear that there is some intimate relation between the variations of sun-spots, barometric pressure, and rainfall; and as famines in general are induced by a defi. ciency of rain, it is probable that they also may be added to the above list of connected phenomena. What is required in order to gain an insight into the causal relation of these variations is

that they should each and all be studied in greater detail than has hitherto been attempted. Accordingly I commenced, more than a year ago, a detailed investigation into the nature of the abnormal variations of barometric pressure, and have been led to the discovery of some new facts which appear to me to be of sufficient importance to render it desirable that they should be published in anticipation of the theoretical conclusions deducible therefrom.

Commencing with the daily abnormal barometric variations observed at several stations in Western India, it was soon found that as the time over which an abnormal barometric fluctuation extended became longer and longer, the range of the fluctuation became more and more uniform at the various stations, thus leading to the conclusion that the abnormal variations of long

duration affect a very wide area. To test this inference it became necessary to compare the observations recorded at Bombay with those of some distant tropical station. Batavia was chosen, and on curving the daily observations side by side with those of Bombay, the degree of accordance between them was found to be truly surprising, considering how far the two stations are apart. The next step was to compare the monthly abnormal variations of these two stations, and finding that they presented many similar features, as well as some differences, to smooth the variations by taking three-monthly means. The degree of accordance was now found to be still greater, many of the discordances having been eliminated in the process of smoothing; but as some differences were still observable the process was repeated, giving nine-monthly means of abnormal pressure corre

sponding to the middle of the months January, April, July, and October of each year. The curves obtained in this way for Bombay and Batavia were then found to be almost identical in form, but with this very remarkable difference: the curve for Batavia was seen to lag very persistently about one month behind the Bombay curve. Similar results were then worked out from all the available data for the following tropical stations: St. Helena, Mauritius, Madras, Calcutta, and Zi-ka-wei, and for comparison with them the monthly sun-spot areas1 were treated in exactly the same manner. The results are given in the fol lowing table, and graphically represented by the continuo:s curves on the annexed plate :

Taken from the paper by Messrs. De La Rue, Stewart, and Loey, published in the Philosophical Transactions for 1870, p. 122.