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which on the drawings which lie on the table extend over a space of six feet, come from E in the yellow to F in the blue, so (hat you aee that no more than one-third of the visible spectrum has as yet been mapped by Professor Kirchhoff. The rest will, no doubt, in lime be done; but all these lines which we notice on this diagram are contained between the line D in the orange and the line F in the blue. It is very important for us to have a clear idea about these lines ; because I shall have in a future Lecture to explain the cause of the existence of these dork lines in the solar spectrum, and we shall see in what way these rays giveusaclue to the explanation of the chemical composition of the solar atmosphere. Fraunhofer first, in the year 1814, proved that these lines were contained in all solar light. He proved that they were contained in the light of the planets. He observed the spectrum caused by Venus light, and noticed that in the light of Venus these same dark lines occurred; he saw that the line D occurred; he saw 6 double; and on measuring the distances from D to E and from E to F, he found that the relative intervals between these lines were exactly the same in the light from Venus as in the light from the sun. He also examined the light which was given off from the brightest fixed stars—Sirius, for instance; and there he made this most important observation,—that in the Sirius-light, lines or bands were present which were not present in either direct sunlight, or the reflected planet-light. Hence he concluded that starlight differs in its qualities essentially from sunlight, and that these lines which we notice in the solar spectrum are, in some way or other, produced in the sun. This is a conclusion which has been confirmed by all subsequent observations.

If we now ask ourselves, in what way do bodies artificially give off light? we shall find that in almost all cases, except in the case of phosphorescent bodies, light is emitted only when the body becomes hot; that light is produced by high temperature. We all know that the higher the temperature the greater will be the quantity of light which is given off. We all know the difference between tho black heat of the smith's forge and the white heat of the glass furnace. Let us now ask ourselves whether the quality of the light emitted by bodies at various temperatures is different. If I take this piece of platinum wire, for instance, and if I heat it gradually, as I can do, we shall see that first of all we have dark rays of heat given off. [The platinum wire was attached to a battery.] The platinum wire, which does not give us any light, will show us that it is hot by inflaming a small piece of phosphorus which we have here. We can thus prove that the platinum wire, although it does not visibly glow, is yet hot enough to ignite our piece of phosphorus. If we diminish the length of our heated wire, we shall thereby increase the heat, and we observe that the wire gradually becomes of a dull red heut; it gradually gets brighter and brighter until itatlast becomes whitehot. Now then, what is it that is going on in this platinum wire ( It is this: first of all, at a certain given temperature the platinum wire gives off red rays, or it becomes red hot; at a higher temperature it begins to give off yellow rays, or it becomes yellow hot; and at a certain higher temperature it gives off blue rays, and becomes what we may call blue hot j and then at a still higher temperature violet rays are given off together with the red, together with the yellow, together with the blue; and we then observe that it is white hot. We then get that combination of colour which produces on our eye the sensation of wliiteness, and we then say that the body is white hot.

That this is the case I hope to be able to show you. I have here three cylinders, one is filled with a blue liquid, one is filled with a yellow liquid, and the other is rilled with a red liquid,—that is to say, the space between the outer and inner cylinders is filled with liquid. I have a hollow space here within which I can place a coloured flame. If I heat any substance iu the interior of this coloured

glass, that substance will become visible to my eye through the blue glass when the heated body gives off blue light. Blue light comes through this liquid, and no other kind of light can pass. That no red light and that no yellow light will pass through this I can easily show you. Here, for in«tance, I can make a yellow flame. I will pi ice the lamp in the interior of this cylinder, and then if I place a little bit of common salt in the flame, we do not see the flame through the jar. Although this flame is glowingnow with an intense degree of yellow light, we shall observe no light coming through. If I place a red flame in the same jar, we shall not be able to see that this flame is coloured at all red in this blue glass. The same holds good, then, for these other vessels. Here I have some yellow solution through which only the yellow light will pass. No blue light and no red light can pass through this cylinder; and here I will show you that we get no red light. The flame is now burning with a bright red flame in the cylinder, surrounded by the yellow solution, but nothing is seen but a slight yellow tinge. Through this cylinder, an the contrary, red light will pass, and only red light.

Now, if what I say is true, if the platinum wire, on being heated, first gives off red lig it, then gives off yellow light as well, and lastly gives off blue light, in addition to the other two, I shall be able to show you this fact by gradually heating up the wires. We will now put our wire in contact with the battery, and then, when the lights are turned down, I will show, first of all, that we have, when we gradually heat the platinum, the red light only visible. The wire is now glowing. We have an intensely red light given off. [The platinum wire was in three pieces, one of which was placed in each of the three differently coloured cylinders.] The red platinum wire is visible through the red cylinder, Dut it is not visible through the yellow and the blue cylinders. If I now increase the temperature of my platinum wire, I shall sec it through both the red and the yellow liquid j but I shall not see it through the blue cylinder. Here we have the red and the yellow glowing, but we cannot see, or we can scarcely see, the blue. That shows that at the temperature which the platinum wire at this moment possesses no blue light is given off; that is to say, the temperature at which the platinum wire has arrived is not sufficient to cause it to give off blue rays, although both red and yellow rays are emitted. When I increase the temperature still more, all the wires glow, blue light is given off, and the platinum wire appears white hot.

It is the property of all solid and liquid matter, that when it is gradually heated the kind of light given off undergoes an alteration, so that the quality of ttie light varies with the temperature; but we are acquainted with a kind of matter which acts in a totally different way: we are acquainted with a kind of matter which we cannot heat so that it will give off every kind of light, or even these three particular kinds of light. If I make a gaseous body luminous, I find that it has the property of giving off only a certain kind of light; that is to say, if I take, for instance, this body—common salt—and make it a gas, which I can do easily by placing it in a colourless coal-gas flame, in which it is heated to the point ut which it gives off light—this yellow light. This sodium gas cannot be heated up to a point at which it will give off any other kind of light than this yellow. We pan never get blue-hot sodium vapour; we can never even get red-hot sodium vapour; wc can only get it yellow hot. In all the different temperatures to which we expose this sodium vapour we get only the same yellow colour. We have here, now, first of all, the flame and coal-gas of which the temperature, according to calculation, is 2350 degrees" centigrade. Now, here we have a flame of carbonic oxide gas, and its flame possesses a much higher temperature than the coal-gas; its temperature is 3041 degrees centigrade. Here we have a flame of hydrogen burning in air; the temperature of that flame, which is higher still, is 3259 degrees centigrade. Here we have the oxy-hydrogen 222

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Manchester Literary and Philosophical Society.

{ Chemical News, I April 19. 1862.

flame, that is to say, a mixture of oxygen and hydrogen which burns together and produces a much higher temperature—a temperature of 8061 degrees centigrade. We shall notice that when we bring a sodium compound into these different flames, which vary in their temperatures, we get the same yellow colour produced in all; and if I obtain a much higher temperature, which I can do by means of the electric spark, we likewise get only this yellow light. Here I have an electric spark of a very much higher temperature than any ef these flames,—how much higher, I suppose nobody knows,—but still the luminous sodium vapour remains unchanged in its colour. If I heat another gaseous body which will give us a red light, we shall in like manner see that this red light of the luminous gas is visible at all these different temperatures, even at the highest temperature. But we must remember that there are exceptions to this rule; and those exceptions I shall have the pleasure of bringing before you on the next occasion. The general rule is, however, as I have stated it, that luminous solids give off a different quality of light when they are differently heated; and luminous gases give off the same kind of light at all different temperatures.

If we now examine these kinds of light given off by solids and by gases more narrowly—if we examine it by means of a prism, what do we find? We find that so long as we have a solid body to work upon—as long as we have a glowing solid or a glowing liquid which is producing the light for us, so long do we get a continuous spectrum—a spectrum without a break.

But when we examine the spectra of luminous gases, we see that these spectra are discontinuous and broken. Here we have a continuous spectrum. It is the spectrum of the white hot solid carbon points. We have here, between certain limits, light of every degree and refrangibility emitted. Solid bodies, then, when heated emit light of every degree and refrangibility; whereas gases when heated emit light of only certain degrees of refrangibility; and it is this peculiarity which lies at the basis of the science of spectrum analysis. If it were not for this, we should get from different bodies spectra absolutely identical. On looking at the spectra and glowing solid or liquid iron, glowing solid or liquid carbon, and glowing solid or liquid lime, we cannot thus distinguish the chemical nature of those bodies; but if we can by any means make the iron, the carbon, and the lime in a state of vapour, then that luminous vapour gives us the power of saying that iron is present, carbon is present, or lime is present; for we get from each and every elementary body the vapour of which is ignited to its point of luminosity, a spectrum which is characteristic of, and which is peculiar to, this body. With the applications of this principle we shall have more especially to do in our next Lecture.

I will show you simply to-day that we do get bright bands when we employ the vapour of a substance to give us light. Mr. Ladd will now place in the electric arc vapour of the metals copper and zinc. He will place a piece of brass, for instance, in the lamp, and we Bhall see those bright lines which, I have no doubt, many of my audience have already Been in this place before.

In this way, then, by examining the spectra of the elementary bodies in the state of gas, we get the evidence of the presence of such elementary bodies. On this coloured diagram I have a drawing of the spectra produced by the glowing vapours of the alkalies and alkaline earths. Now, every substance produces a peculiar bright spectrum having differently coloured bands. When we examine this with a proper instrument we find that these bands split up into lines as fine and distinct as the fibres of a spider's web J and each metal gives lines having different positions in the spectrum, and, therefore, having peculiar colours.

But we must not imagine that it is only the metals that can be thus detected. This same law holds good for the spectra of the non-metallic bodies. Thus I can show you that the body hydrogen, for instance, will give us a spectrum

peculiar to itself. I cannot, I am sorry to say, show you the absolute spectrum produced by hydrogen, for many of these mosfglorious phenomena cannot be presented on a large scale. These things we must see with our own eyes, and only one pair of eyes at once; but I can Bhow you that the colour of the electric spark in hydrogen is quite different from the colour of the electric spark in air. I will pass the electric spark through air and through hydrogen, and you will see the difference of colour. The gas becomes luminous, as the electricity passing through heats the little particles of hydrogen to the point at which they give out light. Then they gi ve out light of one particular kind only, a representation of which you see on this diagram. The hydrogen spectrum consists only of one bright red line, and of one bright blue line here,—that is to say, it gives off only two kinds of light, one a red kind of light, and the other a blue kind of light. On the other hand, the colour which glowing nitrogen gives off is totally different; its spectrum contains many beautiful violet bands.

In the next Lecture, ladies and gentlemen, I shall lay before you the application of these principles to the analysis of terrestrial matters, and explain the mode in which the spectra of the various metallic and non-metallic elementary bodies can be obtained, and also the mode in which we can detect the smallest quantities of these various elementary bodies when present.

MANCHESTER

LITERARY AND PHILOSOPHICAL SOCIETY.

Ordinary Meeting, April i, 1862. J. P. Jocle, LL.D., F.R.S., President, in the Chair. Mr. Alfred Fryer stated that he had recently been making a series of experiments with the oxyhydrogen light, with a view to determine what substance made incandescent produced the greatest amount of light. He operated on various salts of calcium, magnesium, strontium, barium, and also upon some other substances. The best results were obtained from magnesium. The sulphate of magnesia, when baked, yielded a bright light, but was decomposed by the heat; and the sulphuorus acid escaping was very unpleasant. Calcined magnesia succeeded the best of all; but when the powder was used, the gases blew it away. When the powder was mixed with water, and afterwards dried, the cake was friable; and when the dry powder was pressed into a mould by means of hydraulic pressure, the cake split up into laminae when subjected to the gases. After many experiments with the materials in different proportions, it was found that sulphate of lime one part, and calcined magnesia two parts, mixed with watcT and modelled into a cake and dried, produced the best results. This, however, is not all that could be desired, as in time the cake becomes cracked and fissured by the gas. The illuminating power is to that of lime, pressure and volume of gas being equal, as 54 is to 27. The experiments have been conducted with oxygen and the coal gas supplied to Manchester. The jet used is a form supplied by Mr. Dancer, a jet of oxygen being surrounded by an annular jet of the coal gas. MrT Dancer has further improved the jet by allowing the oxygen pipe to project beyond the hydrogen, and by not contracting the aperture of the hydrogen pipe. Mr. Alfred Fryer exhibited the light which he had explained, and the effect produced was very striking-.

Professor Roscoe read a communication, by Professor Clifton and himself, entitled, "On the Effect of Increased Temperature upon the Nature of the Light Emitted by the Vapour of certain Metals or Metallic Compounds."

A Paper was read, entitled, "Notes on Calorific Phenomena," by J. C. Dyer, Esq., V.P.

The author states that the essences of matter, their number and their forms, are only known to us by their

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observed properties and mutations ; that conflicting theories on physics arise from the various interpretations given to the same phenomena; and if unable to reconcile such differences, further inquiry, with that view, may not be improper, whilst the laws of nature rest on debateable grounds. That practically matter, in its aggregate, is found to consist of two sorts or classes—the " ponderable" and the "imponderable"—gravity and elasticity serving to distinguish their respective inherent properties. That as no tests of weight or measure can apply to the latter, its mutations and action on other bodies are the sole means we have of forming any judgment concerning its agency in the laboratory of nature. That the calorific element, or heat, is assumed to be the one "sole imponderable element which pervades matter and space throughout the universe," and it constitutes the elastic forces reacting upon and balancing the gravitating forces in all other bodies. The elemental state of heat must be taken as distinct from its other three states of sensible, radiating, and specific heat, commonly recognized. That elemental heat is acted upon by mechanical and chemical forces, and the changes which it undergoes from the one to the other conditions of heat, give rise to atmospherical phenomena known as electrical, magnetic, and optical; as also to the entire range of meteorological changes, as set forth in the paper. That by the mechanical forces of the earth's motion in its orbit and diurnal rotation, acting upon the elemental medium, its equilibrium is disturbed and motions generated which afford rational explanations of the luminous and ordinary electrical and magnetical conditions of the atmosphere, as indicated by their respective meteors. That by the action of chemical forces, great mutations of heat arc continually going on; for example, the heat which on a vast scale abounds in vapour, is given out as clouds are formed, and accounts for the positive and negative electricity ; and also, when redundant, for lightning from thunder clouds. As much heat is evolved above the clouds, where cold prevails, it must become elemental or neutral there, and justifies the inference that it is identical with the electric fluid, as above said. That electricity and magnetism are but diverse actions of one element has been proved, and their action on matter proves their materiality. The mechanical and chemical action of light proves its materiality also; and that light and heat are identical has been clearly established. The plurality of imponderable elements is, therefore, disproved by the fact that the mutations of the one element fully account for all of the phenomena attributed to several. The gravitating and elastic properties of matter constitute their statical and moving forces, for ever balancing each other. The former of these forces would consolidate the material universe *' with lightning speed," but for the reaction of the latter force. There is no reason why the force of gravity should be measured by the established laws of falling bodies, except that experiment has shown the velocities actually attained by them in vacuo. But this vacuum is the absence of air only, not that of the elastic "medium;" and it is this that holds the poise of matter throughout illimitable space.

• MICROSCOPICAL SECTION. March 17, 1862. E. "W. Binnet, Eta., F.R.S., F.G.S., in the Chair. Twelve specimens of soundings were received from Captain George Kandall, of the barque Brazil, taken on the north coast of Brazil; also five specimens from Captain George Murray, of the ship Finzel, taken off Robin Island, Table Bay; coasts of Sumatra, Java, and St. Helena.

Mr. H. A. Iiubst made a donation of eight slides of diatomacre of various kinds; also specimens of fibre from the bombax, or East Indian cotton-tree, and the fibre of the asclepias syriacus from Bengal. Some conversation aTose upon the adaptation of these fibres as substitutes for cotton, but, although fine and silky, there is not sufficient

strength in the staple to render them fit for manufacturing purposes.

Mr. Blandfobd presented, through Mr. Hurst, a number of specimens of the tongues of mollusca from Burmah, upon which Dr. Thomas Alcock reported that there were four species,—two being fresh water, Melania variabilis, a species of paludomus; and two land shells, different species of cyclophorus. Cyclophorus belongs to a section of the order Pulmonata, distinguished by having on operculum or door to the mouth of the shell, and by having a type of teeth similar to that of the pectinibranchiata. Cyclostoma elegans is a British representative of the same group.

Mr. Cueftiiam exhibited a prism which he uses to illuminate objects under the microscope with the variously coloured lights of the spectrum in succession, instead of ordinary light. He finds that details of structure are more distinctly brought out by some of the colours than others; the blue and green rays are also very pleasant to work with, and easily varied by throwing the required part of the spectrum on the mirror below the stage.

Mr. Sidebotham brought before the notice of the meetins Mr. Petichler's process for producing vegetable forms with crystals of bichromate of potash in gelatine, which was ditcovered by him in the preparation of glass plates for photographical purposes, and exhibited at the Microscopical SoirSe given to the British Association at the last meeting. Specimens on large glass plates were handed round, which, when magnified, aptly represent mosses, ferns, and alga?, in beautiful ramifications, which vary in many ways, dependent upon the strength of the solution, temperature, state of the atmosphere, and other causes. Mr. Sidebotham called especial attention to the peculiarity of the form of crystallisation, and to the fact that an inorganic salt, in contact with organic matter, should produce vegetable forms.

The Secretary then read a paper by Mr. Petschler, describing the plates and the process. Glass plates, Nos. 1, z, and 3, were coated with collodion, on the surface of which a hot mixture of gelatine and bichromate of potash had been poured, then allowed to cool and to dry spontaneously. In a few hours the crystals began to form and ramify themselves over the plate. The mixture was composed of three parts of gelatine and water, twenty grains to the ounce, to one part of a saturated solution of bichromate of potash. Plate No. 4, the same mixture spread hot without collodion. On the corner of the plate the crystals have been dissolved out with water, showing skeleton traces in the gelatine left behind. Plate No. 5 is covered with collodion and a solution of bichromate without gelatine. Plate No. 6 was first covered with the mixture and then with glycerine, but no crystallisation took place. It was then dried with strong heat, gelatine and bichromate poured over hot, and then allowed to crystallise. Plate No. 7, prepared as No. 4, with gelatine and bichromate without collodion. After the crystals were formed, the plate was dipped into a solution of nitrate of silver, which changed the salt into the red chromate of silver, insoluble in water, but soluble in hyposulphite of soda, ammonia, &c. In one corner the crystals were dissolved out, leaving their casts in the gelatine. Plate No. 8 was prepared as 1, z, and 3, by collodion and the mixture, and after the formation of the crystals changed into red chromate of silver as No. 7. Plate No. 9, prepared as No. 6, with glycerine dried with great heat, then coated with the mixture, and treated with nitrate of silver as No. 7. The great variety and beauty of these forms of crystals could with difficulty be represented by drawings. The Author believes that no chemical combination takes place between the salt and the gelatine, but that the latter acts simply as a medium. The gelatine, when firm, retains a certain quantity of moisture, which is favourable to crystallisation; but when the moisture is driven off by heat the crystallisation is suspended.

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In the course of the conversation which ensued, the Chairman referred to the ramified form in which the salts of some metals were found naturally in agate, slate, and even trap rock, where the oxide of manganese wag frequently found to have assumed similar forms.

Mr. Mosley suggested that the arborescent forms might perhaps arise from the tenuity of the solution, from the resistance of the gelatine to allow of crystallisation in the usual Thombic form, and possibly to the subtle electrical or galvanic action supposed to be excited during crystallisation. Some years ago he had obtained from solution of bichromate of potash tree-like forms with spreading branches and pendent rhomboids, which under the polariscope appeared like a tree with gems of rich colours for fruit. Mr. Mosley also exhibited an edition of Baker's work on the Microscope (London, 1785), with many engravings of vegetable forms in crystals of manna, salts of antimony, copper, &c.

Mr. linoniF.ua exhibited a drawing of a small animal he found leaping on the surface of the water in his aquarium, supposed to be identical with the species of Podura found last year by Mr. Lynde.

NOTICES OP BOOKS.

Address of the Chairman of the Great Central Gas Conturners' Company to the Gas Consumers of the City of London. 1861. This pamphlet is a defence of the Great Central Company for joining the Chartered Companies in raising the price of gas when the Metropolis Gas Regulation Act of i860 came into operation. The legality of the matter will have to be settled in a few days by the judges; the policy of allying themselves with the Companies they started to oppose the Directors must settle for themselves. As the Act of i860 compels the supply of gaa 14 per cent, better than the Great Central Company contracted to supply for four shillings, there would seem to be no immorality, whatever the impolicy, in their raieing the price 11 per cent.

CORRESPONDENCE.

Downing v. Chance. To the Editor of the Chemical News. Sia,—A friend has just called my attention to your "editorial comments,' and to your " report'' of the trial, "Downing v. Chance," at Worcester Assizes (which you erroneously print Stafford;, and which appeared in your Number for April 5.

In your " editorial " you make mc say, "does not remember the composition of cyanogen, for the compounds of hydrogen are so complicated j" and in your report of the trial you make me say, " He could not just then refresh his memory as to which two gases cyanogen was composed of at the moment; some of the compounds of hydrogen weTe so difficult."

I said neither of these. The question put in crossexamination by "Counsel" was, " What is the composition of cyanogen i" Believing that the question was only put to cause a wrangle, as cyanogen could have nothing to do with the case, I replied, "I decline to answer."

There is all the difference between giving a wrong answer, and not replying at all.

Of course the question will arise, "Why refuse to answer?" Perhaps if I had had five minutes' reflection, I might have thought differently; but at the moment I considered that I exercised a sound discretion in thus stopping a probable series of irrelevant questions, not put for the elucidation of the truth, but solely to bewilder the jury.

l)y a singular coincidence, a few days after, the samp chemists and the same "leading counsel " again appeared in "hostile- array" before the same "judge," at Stafford Assises, when full opportuuity was given by me to "the other side" to put any questions they pleased, if they dared j but they knew better.

I just add that myself and Mr. Williams can well afford to suffer any amount of "criticism," under the not trifling satisfaction that in both " trials" "special juries" gave verdicts to our clients, the " plaintiffs."—I am, &c.

ALFRED BlBD.

Birmingham, April 15.

Paraffin Matches. To the Editor of the Chemical News. Sib,—In your last number, at page 109, you notice my patent for paraffin matches, and append some remarks which are not in accordance with the merits of the case. I therefore send you a halfpenny box of these matches, that you may see for yourself that they burn with a beautiful flame without either smoke or smell.

You are correct in stating that stearine has long been used in match-making in place of brimstone, but it is difficult to make the wood of such matches catch, whereas with paraffin they ignite immediately; and you overlook the fact that such matches are dearer than common matches, whereas the great merit of my patent paraffin matches is that they are as cheap as the common brimstone match, thus making it an article for the million,—a large halfpenny box of matches without any smell, in place of the obnoxious sulphurous match.—I am, &c.

R. Letcufobd.

Clarifying Wine. To the Editor of the Chemical News. Sib,—May I, as a subscriber to your valuable periodical from the first, ask the solution of the following questions: —"Why pure albumen (the white of egg) is used for the clearing of red wines in preference to pure Russian isinglass :" and, also, "Why pure Russian isinglass is used for the clearing of white wines in preference to pure albumen r" and, also, "What is the difference in their action ?"—the constituents of the wines being in most cases similar, at least so far as the quantity of tannic acid is concerned. I am, &c.

Ik Vino VERITAS. Plymouth,

MISCELLANEOUS.

Monochlorinatcd Mulphurir Acid.—Rosenstiehl (Comptes-Itendus, t. liii. p. 658) dropped fused chloride of sodium into a retort containing anhydrous sulphuric acid, and applied sufficient heat to melt the aeid. He then distilled to dryness, and obtained an oily, colourless liquid, sp. gr. 1.762, which boiled between 1450 and 1500, turned a little less that anhydrous sulphuric acid, and carbonised energetically organic matters. Analysis led to the following as the formula of the compound, 8, Os CI. With manganates it disengaged chlorine, gave chlorochrouiic acid with chromates, and chloride of acetyle with acetate of soda,—proofs that the new body is an energetic ohlorinizer.

ANSWERS TO CORRESPONDENTS.

Strt/clutinr.—ln answer to tho question of B. W C, we can refer him to a method of Mr. Horstey's, which ho will find reported ill the "Proccodinga of tho British Association for 1856."

F. X, Q.—tou would most likely hare chloride of nitrogen formed.

THE CHEMICAL NEWS.

Vol. V. No. 125.—April 26, 1862.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

Researches of Pasteur respecting the Theory of Spontaneous Generation, translated and condensed by M. C. WniTE, M.D.

The theory of spontaneous generation was long since proposed to account for the origin of beings whose germs were too minute or too obscure to attract attention. Ono after another the different organisms supposed to arise from spontaneous generation have been proved to originate from germs. At present the question of spontaneous generation concerns only the origin of entozoa and those minute organisms which can be studied only with the aid of the microscope, as moulds (minute fungi) and infusoria, both animal and vegetable. The common theory that the spores or germs of these minute organisms are constantly floating in the atmosphere ready to start into activity whenever they meet with a suitable nidus, has found an able advocate in M. Pasteur, of the Normal School of Paris, who has published in the Comptes-liendus" a series of valuable papers on this subject, the substance of which I have translated.

In order to collect and examine the solid particles floating in the atmosphere, Pasteur placed soluble guncotton in a glass tube, and, by means of an aspirator, caused a current of atmospheric air to pass through it for several hours. The cotton was then dissolved in a mixture of alcohol and ether, and the atmospheric dust deposited at the bottom of the fluid in a conical glass was examined in the microscope. The sediment thus collected contained grains of starch and such other dust as is ordinarily found on surfaces exposed to the air. When submitted to the action of concentrated sulphuric acid, the starch was soon dissolved, while other particles remained undissolved and had all the characteristics of the spores of ordinary mucedines, which are known to resist the solvent properties of concentrated sulphuric acid. [It is worthy of notice, that certain minute fungi an capable of decomposing a solution of sulphuric acid. A few years since, a little mould developed in the solution of sulphate of copper, used for electrotyping in the department of the U. S. Coast Survey at Washington, proved an intolerable nuisance. It decomposed the salt, assimilating the sulphuric acid, and rejecting the copper which was deposited around its threads in a metallic form. From this it appears that sulphuric acid does not prevent, but may rather assist the growth of certain fungi.—TV.]

To determine the action of atmospheric air, and of atmospheric dust upon fermentation, putrefaction and the appearance of organisation, Pasteur adopted the following methods:—

Cvmptu-Rtndtu, i860, t. 1. Ji,

A flask was about half filled with a fluid consisting of water containing in solution about ten per cent, of sugar and from two to seven parts in a thousand of the scum of beer. The neck of the flask was drawn out in the flame of a lamp and attached to a platinum tube, Jjth of an inch in diameter, which was then heated to redness. The fluid was boiled for two or three minutes to expel all air from the flask, when it was aliowed to cool very gradually, and as it cooled the air which entered the flask was calcined, and all organic germs it contained were destroyed by passing through the red-hot platinum tube. When the flask hod thus cooled to the temperature of the surrounding air, the neck was hermetically sealed. The flask was then removed to an oven, and kept at a temperature of 8o° or 900 F. for an indefinite period, without producing any organisms or undergoing any change whatever.

To test the influence of atmospheric dust upon a fluid thus hermetically sealed, Pasteur placed a pledget of cotton or asbestos in a small tube, and caused a current of common air to pass through it by means of an aspirator. This small tube containing the cotton or asbestos, loaded with atmospheric dust, was then transferred to a larger T-shaped tube, one end of which was connected by india-rubber with the sealed flask, another end was connected with a platinum tube heated to redness, and the third being connected with an aspirator, the apparatus was easily charged with calcined air, and all the common air was expelled. The neck of the flask was then broken within the T-shaped tube, and the small tube containing the atmospheric dust was passed into the flask, with access only of calcined air. The neck of the flask was then again hermetically sealed by means of the blowpipe. Many flasks were prepared in this way, and in every case, after standing in a warm situation for twentyfour to thirty-six hours, vegetation appeared in the same manner as it' the contents of the flask were exposed to the open air; but the mould or mucedines appeared first in the little tubes carrying the cotton, which was often thus filled to its extremities. The organic growths which appeared were the same as in flasks exposed to the open air,—viz., of infusoria, bacterium; of mucedines, the penicilium, ascophora, aspergiltus, and some others. When calcined asbestos alone was introduced no vegetation appeared.

It was thus demonstrated that amongst the dust suspended in ordinary air there are always organised corpuscles, and that these powders when mixed with a suitable liquid, in an atmosphere of itself inactive, give origin to bacteria and mucedines such as are furnished by the same liquid in the open air.

Pasteur confirmed these results by another method. Similar quantities of the samo fermentable liquid were introduced into a series of flasks in all respects alike. The necks of the flasks were all drawn out over the flame of a lamp, and bent into a variety of different forms, but the tubular neck of each flask was left with

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