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as in the previous form of the apparatus. On bringing the porous cell into a gas containing carburetted hydrogen, some of the gas diffuses into the cell, causing a rise of the mercury in the glass tube and a corresponding movement of the index.

All these modifications of the apparatus must be watched in order to obtain any information from them; but Mr. Ansell has constructed an alarum, which rings a bell if any quantity of gas SLOWLY ACCUMULATES round the indicator. The instrument Fig. 5 consists of FIG. 5.

one of the thin india-rubber balloons (a) so well known at the present time. One of these is placed on a piece of brass, which can be raised and lowered by a screw. The upper end of the balloon presses against a lever (b), which, when raised, liberates a train of clock-work at (o), and rings a bell (e). To increase the movement of the lever a band of linen is bound around the equator of the balloon in order to prevent lateral expansion and to concentrate all increase of volume in a polar direction. If this apparatus be placed in the gallery of a mine, the presence of or an increase in the quantity of mine gas will cause the expansion of the balloon, and consequent ringing of the alarum. The balloon remains in its expanded state until the composition of the atmosphere is

altered.

Mr. Ansell has devised an instrument which for elegance and utility far surpasses all the others, as it admits of the determination of the quantity of mine gas present in a mixture. The apparatus consists of a small aneroid

barometer, the case of which is made perfectly air-tight, but the interior of which may be placed in communication with the external air by opening a small screw fastened on the handle. The brass back of the barometer is replaced by a thin plate of porous earthenware, and may be covered with a brass cap or back placed on a hinge like that of a watch. Under ordinary circumstances the screw remains open, but when it is required to test the gas in a mine, the screw is closed and the cap removed from the porous plate. Immediately diffusion takes place, and the pressure increasing, causes a corresponding movement of the hand of the barometer. In about forty-five seconds the maximum effect is produced, when the position of the hand indicates by means of a vernier the percentage of mine gas present. If the apparatus be left for a sufficient time, the internal pressure forces the excess of gas through the porous plate, and the needle returns to the zero point. On subsequently allowing diffusion to take place into pure air, the index retrogrades to the same extent (if the mixture does not contain more than 10 per cent. of mine gas or "firedamp") to which it had previously advanced. This apparatus, which is not larger than an old-fashioned watch, will undoubtedly prove of great service to the mine overseer, as it can at any time be carried into the gallery of a mine. The percentage of gas is determined in less than a minute.

As is to be expected, the motion of the train of trucks running into, or out from the pit, causes a variation of the pressure, therefore it is necessary to avoid such intervals in making observations by the instrument last described. It is well to mention that temperature need not be taken into account, for it is found that the temperature of the same part of a mine does not vary from year's end to year's end. The instiments denoted by figures 2, 4, and 5 are connected with telegraph arrangements, and these as well as the aneroid barometer have given full satisfaction to practical miners in several mines where they have been tried.

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THE minutes of the previous meeting were read and confirmed, and the several donations to the Society's library were enumerated and acknowledged. These included the Annual Report for 1864 of the Danish Academy of Sciences, the Transactions of the Royal Society of Edinburgh, the Proceedings of the British Pharmaceutical Conference (Birmingham, 1865), and copies of Dr. A. W. Hofmann's "Introduction to Modern Chemistry," besides several other works and periodicals of scientific interest. The candidates proposed for admission into the Society were, for the first time,-Mr. Thomas B. Redwood, 19, Montague Street, Russell Square; Mr. John Conroy, Christ Church, Oxford; Mr. Robert Henry Smith, Rodney Barclay and Speir, chemical manufacturers, NewcastleStreet, Pentonville; and Mr. James Speir, of Messrs. upon-Tyne. For the second time were read the names of John Percy, M.D., F.R.S., lecturer on metallurgy in the Royal School of Mines; Mr. Ernest T. Chapman, George Street, Portman Square; Mr. Charles N. Ellis, Bow Common; and Mr. Thomas Ward, Bolton. The names of the following gentlemen were read for the third time, and they were duly elected by ballot,-viz., John Hunter, M.A., Queen's College, Belfast; Mr. Theodore Maxwell;

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Mr. W. J. Barnes, Buckhurst Hill, Essex; Mr. W. E.
Bickerdike, Dalton Square, Lancaster; Mr. Richard Fitz
Hugh, Nottingham; Mr. Alfred Gardiner Brown, M.R.C.S.,
Trinity Square, Southwark; and Dr. William B. Ritchie,
Belfast.

A communication entitled "Notes on Pyrophosphodiamic Acid" was presented by Dr. J. H. GLADSTONE, F.R.S. The author stated that it had been his original intention to address the Society upon the subject of a newer product with the investigation of which he had been lately engaged. but inasmuch as the analyses of pyrophosphotriamic acid and certain of its compounds were not yet completed, the speaker preferred for the present to limit himself to an account of some new modes of preparation, and a further description of the properties of pyrophosphodiamic acid. This substance, originally called deutazophosphoric acid by Dr. Gladstone, was more accurately described in a paper by the late Mr. Holmes and himself, which was read before the Society about eighteen months ago. Its formula is, P2Ñ2H,5, in which two atoms of the hydrogen are replaceable by metals. Three methods of preparing it have been previously described-1st, by decomposing chlorophosphide of nitrogen by an alkali; and, by saturating phosphoric anhydride with dry ammoniacal gas; and 3rd, by saturating oxychloride of phosphorus with the same at a low temperature, and dissolving in water. The two stages of the reaction were explained thus :—

=

59

PC12O+2NH, PNH,Cl2O+NH,Cl. 2(PNH,CI,O)+3H2O = P2Ñ2H2O,+4HCl. The two last methods may be modified by using the very strongest solution of ammonia instead of the gas. There are also other methods of producing this acid-4th, by throwing pieces of pentachloride of phosphorus into the liq. ammon, fort., when some pyrophosphotrinmate of ammonium is at the same time formed; but the main result accords with the following equation :

2PC1, +12NH3+5H2O = P2N2H2O2+10NH ̧Cl. 5th, by exposing oxychloride of phosphorus to ammonia gas at 100° C., when four equivalents of the latter are absorbed (instead of two, as described under the third method), and submitting the product to the subsequent action of water

=

PC1,O+4NH, PN,H,CIO+2NH,Cl. 2(PN,H ̧CIÓ)+3H2O =P2N2H¿O ̧+2ÑH ̧C]. 6th, by performing a similar experiment at a much higher temperature, the same amount of ammonia yields different products, among them one which is insoluble in water, but when heated with sulphuric acid dissolves with the formation of pyrophosphodiamic acid; 7th, the same compound is formed when pyrophosphotriamic acid is heated in a similar manner with sulphuric acid

P2N,H,O+H2SO,+H2OP2N2H2O2+NH,HSO

=

diamates of silver, barium, calcium, zinc, copper, nickel, etc., have been examined by the author; they are for the most part flocculent precipitates readily soluble in acids, ammonia, and even in the aqueous solutions of ammoniacal salts. The mercuric chloride gave no precipitate, neither did solutions of aluminium, chromium, and magnesium. The pyrophosphotriamic acid, of which the formula is given above, P2N,H,O,, was stated to be insoluble in water, but readily soluble in warm acids.

The CHAIRMAN, after moving a vote of thanks, inquired of Dr. Gladstone the grounds upon which he used the prefix "pyro" in connexion with the diamic and triamic acids, since these bodies were not produced by fire? Dr. GLADSTONE replied that the bodies in question were framed upon the type of pyrophosphoric acid. Dr. FRANKLAND would rather have confined the use of the term "pyro " to tetra-basic acids. Dr. ODLING entertained a different opinion, and preferred to have regard to type rather than to basicity, thus: Pyrophosphoric acid {or PHO or (PO) (HO). Pyrophosphodiamic acid (P2O3)(HO)2(NH2)2. The mono-acids would be respectively—

(PO)(HO).. and (PO)(HO),(NH2). Or, starting from the oxychloride of phosphorus, we should look for the following amides :

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Dr. HUGO MÜLLER said he could avail himself of the opportunity of making a few remarks on the subject of "Phenylo-Phosphoric Acid." Some years back, when engaged with some experiments on phenyl-compounds, he examined the deportment of phenylic alcohol with phosphoric anhydride and chloride of zinc, with the view of obtaining by means of these agents the hydrocarbon phenylene. He found, however, that phenylic alcohol was not acted upon as expected; and whilst chloride of zinc showed no action whatever, the influence of the phosphoric anhydride was confined to the formation of phenylophosphoric acid. On mixing crystallised phenylic alcohol with phosphoric acid, a pasty mass is formed with elevation of temperature, which, after the application of a further heat, becomes gradually homogeneous. On raising the temperature, some of the phenylic alcohol distils over unaltered, and the residue, on being dissolved in water and treated with carbonate of barium, yields phosphate of barium and a solution of phenylophosphate of barium. The metal having been separated by sulphuric acid, the aqueous solution, on being carefully evaporated, yields the which separates from the concentrated solution. phenylophosphoric acid forms well-crystallised salts, which show a considerable degree of stability. The potassium and ammonium compounds are very soluble in water, and exist in the form of fibrous crystals. The magnesium salt is readily soluble and indistinctly crystalline. The barium salt is less soluble than the former, and separates from its concentrated solutions in the shape of beautiful long silky crystals resembling caffein. On mixing a solution of phenylophosphate of barium with acetate of lead, a white precipitate is obtained, which, after a short time, becomes converted into a mass of silky crystals, or in more dilute solutions the lead salt separates gradually, or upon evaporation takes the form of beautiful crystallisations, which are very similar to the barium compound. Nitrate of silver gives with the free acid, as well as

Or, 8th, when the same acid is heated alone until it begins to suffer decomposition; 9th, Gerhardt's phosphamide, when heated with sulphuric acid, also yields pyrophos-phenylophosphoric acid in the form of a heavy oily liquid, phodiamic acid, thus

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The fourth method of preparation was exhibited by Dr. Gladstone, and the characteristic reaction by which the pyrophosphodiamic acid could be identified was shown experimentally. [The pentachloride of phosphorus acted rather violently upon the aqueous ammonia; the solution was filtered, and then strongly acidified with sulphuric acid (one of oil of vitriol to two parts of water); a few drops of ferric chloride were added, and the solution heated, when a white flocculent precipitate appeared. This ferric compound could be easily distinguished from the ordinary phosphate of iron, which it much resembled in physical aspect, by its solubility in ammonia and production in strongly acid solutions. The pyrophospho

The

with the solution of the barium salt, a flocculent white precipitate, which soon becomes changed in colour to yellow and brown. Solutions of copper, nickel, cobalt, and zinc do not give precipitates in the cold, but when heated produce flocculent precipitates, which re-dissolve on cooling. All the salts of phenylo-phosphoric acid exhibit the highest degree of solubility at a temperature between 40 and 60° C., and show in this respect a great resemblance to the salts of the corresponding ethylophosphoric acid. [Specimens of the lead and barium salts were exhibited by Dr. Müller.] The author further stated that the barium salt appeared to be the only one which was anhydrous, and its organic analysis by combustion presented some difficulties; on this account the constitution of the acid had not yet been accurately determined. The body was altogether different from the phenylic phosphate of Professor Williamson.

Professor A. H. CHURCH made a statement respecting the properties of ethylo-phosphoric acid, and referred particularly to the fact of its salts being less soluble in boiling water than at a lower temperature.

A vote of thanks to Dr. Müller was proposed, and the CHAIRMAN, previous to the adjournment of the meeting, took occasion to announce that the committee appointed by the British Association for the special consideration of weights and measures had invited the co-operation of the Chemical Society in suggesting a suitable metal or material from which to manufacture the standards of the new metrical system, the use of which had already been legalised in England. The committee would probably attend the next meeting of the Society, on the 21st December, and the Fellows were therefore requested to give the subject their best attention in the interim.

SOCIETY OF ARTS.

CANTOR LECTURES.

Several theories have been promulgated by chemists and physiologists as to how the oxygen acts to convert venous into arterial blood. Liebig assumed that the blood dissolved oxygen as water dissolves that gas and others; and he explains the greater solubility of oxygen in the blood than in water, by asserting, and that on experinient, that phosphate of soda, which exists in blood, facilitates the solution of oxygen in that fluid. Dumas states that it is the iron which exists as one of the elements of the colouring matter of blood, called, as above stated, hematosine, which fixes the oxygen in the arterial blood, and yields it again to various organic matters, either those originating from glycogen or those resulting from the wear and tear of life, and which may be considered as refuse matters which require to be removed from the system. The iron thus becomes deprived of its oxygen, and is ready to reabsorb a fresh quantity when it comes again in contact with the oxygen of the atmosphere in the lungs.

These theories do not appear, so far as I am aware, to have received the general sanction of physiologists; and I therefore deem it to be my duty to call your attention to some interesting optical researches, due to that eminent savant, Professor Stokes, of Cambridge. That gentleman has observed that when a small quantity of blood is mixed with water, and the whole poured into a small tube, and this, in its turn, placed in such a position as to allow a ray of light to pass through the blood solution, and that then the ray of light is made to pass through a prism, he finds that the spectrum so produced has undergone certain modifications, which consists in the fact that certain tints or colours of the spectrum have disappeared; and he, moreover, observes that these "bands of absorption," as he calls them, are characteristic, for they differ according as the blood placed with the water in the tube is arterial or venous, and so delicate is this mode of investigation that he can discern the slightest modifications which

"On some of the most important Chemical Discoveries made blood undergoes. In fact, I may state en passant that he

within the last Two Years."

By Dr. F. CRACE CALVERT, F.R.S., F.C.S.

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Although it is impossible in a lecture like this to attempt to give a correct idea of all the phenomena connected with respiration, and all the data which bear upon that important function of life, I may be permitted to give a few data, which will enable you, I hope, to have a general idea of the present theory of respiration. Man inspires about thirty times a minute, and at each inspiration there rushes into his lungs about a pint and a-half of air, which penetrates into the myriads of cells composing the lungs, and comes in contact there with the blood, as above stated, which it converts from venous into arterial. At the same time a certain quantity of air, or oxygen, is dissolved, which not only affects the above conversion, but displaces from the venous blood a certain quantity of carbonic acid which it contains. Thus it is found by experience that one hundred parts of air that man inspires, contains, in round numbers, twenty-one parts of oxygen; whilst the gases he expires are represented by sixteen parts of oxygen, four parts of carbonic acid, and one part of oxygen which has been transformed into water, thus making up again the twenty-one parts of gaseous matter in the 100 which he inspired. But the production of this carbonic acid is chiefly caused by the action of the oxygen dissolved in the arterial blood during its passage and contact with the animal tissues and the glycogen existing in the capillary vessels; for it is there that we observe the change of blood from arterial to venous, the conversion from venous into arterial being, as above stated, in the lungs.

has applied this mode of investigation to distinguish vegetable and animal matters, which, though having a great similitude, become distinguishable by the simple mode of applying optics to their investigation.

Coming back to blood, I may state that the researches of Professor Stokes on the action of oxidising agents on blood, have thrown much light on the phenomena connected with the conversion of venous into arterial blood. He has remarked that if arterial blood is shaken with an alkaline solution of sulphate of protoxide of iron, or protochloride of tin, it assumes the dark colour of venous blood, and that if he then agitates the same dark purple blood with air, it absorbs the oxygen, becomes oxidised, and, therefore, is converted into red arterial blood.

The facts, joined to many more which can be found in the Proceedings of the Royal Society for 1864, have led Professor Stokes to the conclusion that the colouring matter of blood is the real carrier of oxygen; that it absorbs oxygen and becomes scarlet; and that it yields its oxygen to organic substances during its circulation through the system, and becomes purple or venous blood. He has given to the colouring matter of blood the name of cruorine, and calls it purple or scarlet cruorine either as it exists in the veins or arteries.

I think it is useless to repeat here many facts connected with this subject, and which I brought to your notice in my last year's lectures.

Urine.-Having also dwelt in my last course at some length on the principal elements contained in this important secretion, I deem it my duty merely to call your attention to one or two facts of some immediate importance which have been published since then. One of these is due to Dr. Marcet, who has found in that secretion a substance which, until his investigations, had been unnoticed by chemists. I mean an amorphous or non-crystallisable acid, which he calls colloidic acid, from the circumstance

NEWS

that it cannot pass or diffuse itself through animal membranes. I may here mention that substances in general, according to the theory of Mr. Thomas Graham, the Master of the Mint, may be divided into two classes, namely those which crystallise, and which he calls crystalloids, and those which do not diffuse, and which he calls colloide, from the French word solle, or glue. M. E. Morin has also published some elaborate researches on the relative proportions of oxygen and carbonic acid in urine, and the following table will show you the influence which ex. ercise has upon the combustion of organic matter through the oxygen conveyed in the blood by the cruorine of Professor Stokes, converting the organic matter into carbonic acid, for this gas is found, as you will see, more abundantly in the urine of man when in a state of activity than when in a state of repose :

GASES IN THE SECRETION OF THE KIDNEYS. Quantities of Gases in Composition of the

100 parts of Urine.

From 2.62

to

3.61

Gases. Carbonic acid Oxygen Nitrogen

Activity.

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Repose.

62993 1.89 35°18

100'00 100'00

I wish now to invite your consideration for a few minutes to some interesting facts which have lately been published by Dr. H. Bence Jones, on the extraordinarily rapid absorption of certain substances into the animal system. He has observed that substances, such as lithium and rubidium, will be found to have passed into the whole of the human system three or four hours after they have been administered, either as medicines or as a matter of experiment. In fact, he has found that the absorption is so complete that he has been able to detect their presence in the non-vascular textures of the body; and what enhances the interest of his researches is, that he employed, as a means of analysis, for the detection of these substances, the property which they have of communicating colour to flame, and therefore applied to their detection the spectroscope of Bunsen and Kirchhoff.

Whilst on the subject of the rapidity of the absorption of matter by the body, I may state that a French physiologist has observed that certain saline matters, such as iodide of potassium, nitrate of potash, or acetate of morphia, will pass in a few seconds through the whole of the system. Thus he was able to detect the presence of iodide of potassium in the urine three minutes after it had been taken by the mouth. But certainly one of the most curious instances published of late respecting the absorption of organic matters in the system is that related by Dr. Letheby, and which tends to prove the correctness of statements which have been published in former times, that certain chemists or persons had a secret of producing poisons, the action of which only became manifest a long period after they had been administered. Thus, Dr. Letheby states, in a paper which you will find in the Proceedings of the Royal Society, and which contains some of the facts which he gave in evidence at a coroner's inquest in London, that the death of a person ensued twelve months after he had taken the substance which caused death. A man engaged in a large chemical works in London had inspired, during his labours, a comparatively small quantity of a substance called nitro-benzine (now sold under the name of oil of bitter almonds, and used in large quantities for perfumery, and also for giving taste to various culinary preparations), and that this substance had gradually become converted into aniline (a substance now extensively used to produce colours, and also procurable from coal tar), and had been the cause of the death of

the man.

I would invite all lovers of animal physiology to read with attention the researches of M. Claude Bernard on the physiological action of curarine, or the active principle

of the curare, or the poisonous mixture used by the Indians at Madagascar, and on the banks of the river Oronoco. These researches will be found in several articles published by him in the Revue des Deux Mondes, 1864; and, to excite your interest in reading the articles, I may state on his authority that the death which ensues by the injection into the blood of a trace of this poison may be considered as the most curious and distressing that can be conceived, and he further states that the physiological phenomena which are witnessed during the process of death may lead to the most beneficial application of the substance as a therapeutic agent.

Although time is pressing, I cannot part from you this evening without calling your attention to the fact that every day we are realising the cherished ideas of the alchemist, and of the medical men of the fifteenth and sixteenth centuries, who laboured, the one to extract from substances what they called the quintessence of them, and the other to apply what they supposed then to be such quintessences. From the imperfect state of science, chemistry included, at that time, they were unable to carry out what they conceived to be essential to arrive at a better and more enlightened treatment of disease. They perfectly felt that the extracts or infusions of the plants they had at their command had not a defined action in their treatment. All men of science know with what enthusiastic perseverance Paracelsus advocated the employment of quintessences; and, although in his enthusiastic mind he went so far as to pretend that he carried in the head of his cane the elixir of life, there is no doubt that he and his disciples left a germ, which has gradually grown to be a plant, and that the chemistry of the present day is gradually succeeding in extracting from plants their active principles. Although medical men were convinced of the utility of employing the active principles existing in plants, as quinine, cinchonine (from cinchona bark), morphine (from opium), &c., still we had not a correct idea of the various actions which these diverse alkaloids exerted on the system. We are, therefore, much indebted to M. Claude Bernard for his admirable researches on the therapeutic action of the alkaloids of opium; and owing to his extensive physiological knowledge, as well as his perfect mode of carrying out his experiments, he has proved that we can class the action of the alkaloids of opium under three heads, as shown by the following table :THE ALKALOIDS OF OPIUM. Convulsive. Thebaia. Papaverine. Narcotine. Codeia.

Soporific. Narceia.

Morphía. Codeia.

Not Soporific.
Narcotine.
Thebaia.

Papaverine.

Morphia. Narceia.

Toxic. Thebaia.

Codeia. Papaverine. Narceia. Morphia. Narcotine.

These researches thoroughly prove the correctness of Paracelsus's views, showing that in the employment of opium due consideration should be given to the fact that in the opium there are various agents acting in a defined manner upon the organs of the patient.

I cannot conclude this lecture without drawing your attention to several interesting papers which have been published by Dr. Polli, of Milan; Davanne, Royer, and Le Maire, of Paris, tending to prove that the source of many diseases, especially those of a contagious nature, may be due to the sporules or germs of certain animal or vegetable ferments which penetrate with the air into the system, coming in contact, as it does, with the blood in the lungs of man. The difference between the views of these gentlemen and those who preceded them is that formerly these statements were merely theoretical, whereas these gentlemen, by the aid of the powerful microscopic instruments now brought into use, have been able to trace the presence of vegetables or animals in blood either of

animals or man affected with certain classes of disease. I may cite as an example the discovery in the blood of the carbuncle, of the presence of vibrios and bacteria. (Royer and Davanne.) These facts explain why these gentlemen have applied with such success the most powerful antiseptic agent yet known in the treatment of that diseasenamely, carbolic acid, and there is no doubt in my mind that the spread of either scarlet fever, typhoid fever, cholera, or any diseases arising from the decay of blood or its decomposition, is brought about by the introduction into the blood of certain ferments which completely alter the nature of that fluid, as in the case of the carbuncle and similar diseases. If these views are correct-and I think I am justified in saying that they have the support at the present day of some of the most eminent men on the Continent-the employment of carbolic acid, either to prevent the spread of, if not to cure, these diseases, deserves the attention of the medical world.

it also suspicious. He was not aware that it could be shown that in aggravated cases another class of disease might not be produced. In Manchester we can see the accumulation of matter taking place in the fog to such an extent that it lies like a cap over the whole town, and so increases that every sense is affected, whilst the lungs and eyes suffer severely. The matter in solution in this case is not putrefactive, although injurious, or it would probably sweep us off instantly. Probably no accumulation of putrefactive matter equal in amount ever occurred in the natural atmosphere. It illustrates, however, the mode by which the emanations of the soil are collected in the atmosphere and presented in a concentrated form for us to breathe. He had for many weeks collected dew on a grass lawn in a garden, and from it had obtained organic matters unquestionably collected from surrounding objects, as it was known on one occasion to smell of flowers. If this entered into putrefaction it would of course be unwholesome, but what kind of disturbance of health it would cause it must be for others to find. The evening

MANCHESTER LITERARY AND PHILOSOPHICAL air of a rainy country like this is less dangerous than that

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"The great peculiarity of the season has been the very heavy dews we have had-great luxuriance of pasture nourished by dews and not by rain. I have drawn Professor Simmond's attention to this, as being a predisposing cause of the present cattle disease. Not that it really engenders the malady, but predisposes the animal to take this peculiar type of disease-my own experience from the readings of my instruments some twelve or fourteen years ago having shown that disease of the same type attacked my cattle and destroyed them, and each time when the high temperature of the day and the low temperature of night gave us such heavy dews as to render the herbage quite indigestible."

Mr. BAXENDELL considered it very probable that cattle would be injuriously affected by feeding on herbage which had not been well washed by occasional showers of rain. Dew had little or no washing effect, and it could not remove the impurities which were deposited upon the leaves of plants during long periods of dry weather. The cattle plague is said to have had its origin in Central Asia, and in this region there is very little rain, and the daily range of temperature is very great. The herbage is therefore seldom well washed, and moreover the cattle that feed upon it are exposed to frequent and violent changes of temperature. We have no report of any cattle plague breaking out among the herds on the pampas of South America, where rain falls more abundantly and the changes of temperature are much less violent.

of some other climates where there is more both evaporated and condensed, and neither wind nor rain to remove it. Notwithstanding this, he believed that more than the dew was required, especially in northern climes.

The PRESIDENT also said, that when sitting in a railway carriage with his friend, Mr. James Young, of Bathgate, that gentleman observed that the particles of dust which floated in the air seemed to shine with a metallic lustre, Dr. S. immediately collected some, and found that the larger class were in reality rolled plates of iron which seemed to have been heavily pressed and torn up from the surface. Another and smaller class were less brilliant, and when looked at with a considerable power showed many inequalities of surface which would be interesting to study. Probably these were the particles which were not torn up, but rubbed off. The dust enters the mouth and lungs, and has to be taken as one of the evils of railway travelling, although we do not know that these small particles are worse than those of sand. At any rate, it is clear that some kinds of iron will wear down more readily than others, and we ought to have that which will wear down least. By observing what takes place in the carriages on a dusty day, every man may to some extent compare the iron of different railways. Those which give off the largest pieces in greatest quantities are to that extent the worst, as regards health.

A paper was read entitled "An Attempt to Refer some Phenomena Attending the Emission of Light to Mechanical Principles," by R. B. CLIFTON, M.A., Professor of Natural Philosophy in Owen's College,

The author attempted to show, by analogical arguments, that it is possible to give some account of certain phenomena attending the emission of light, by assuming principles closely resembling, if not identical with, those adopted by Professor Clausius in his well-known paper on "The Nature of the Motion which we call Heat,"*

Matter is assumed in all cases to have its atoms grouped together into molecules, an assumption which seems necessary when the different allotropic states of certain substances are considered.

These molecules are assumed to be in motion, and also the atoms to be vibrating in the molecules; for, whatever may be the laws of the forces which bind together the atoms in the molecules, it is impossible to imagine the molecules to be in motion, and to be subject to mutual actions, without causing motion of the component atoms.

In solids and liquids the molecules are supposed to

The PRESIDENT said that the idea of deriving the cattle plague or any similar epidemic from the organic matter brought down by dew was at least in harmony with much that we had learnt. The dews and fogs of evening over certain lands were known to produce colds, agues, or fevers which could be avoided by rising to a certain height from the ground. There seems little doubt that the mois-remain continually within the spheres of action of neighture in such cases is not the cause of disease, but only the means of conveyance. These diseases were produced by breathing the impure air. We know less of the effect when the matter is condensed and conveyed into the stomach, but the effect of impure water made this use of

bouring molecules, so that the internal motion in a molecule is never due to the undisturbed action of the interatomic forces; the only difference between solids and liquids being that in the former the same molecules are * Phil. Mag., vol. xiv., for 1857.

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