of also extracting the silver and copper as well as the gold which the ore may contain. Further, it may be stated that the process can be profitably adopted in cases where the amount of gold is small, and the expense of mercury consequently too great. Without entering here into all the details of the numerous (about one hundred) experiments which I made some years since, before I finally arrived at the new method of extracting gold, which I have now the honour of communicating to the meeting, allow me to state a few facts which are necessary to give a general view of the subject. If 22 parts of pure and finely divided gold, obtained by the reduction of a salt of that metal, be added to 100 parts of pure sand, and placed in a bottle with a saturated solution of chlorine gas for twenty-four hours, only o'5 of gold is dissolved. If the same experiment be repeated, but, instead of chlorine water, a mixture of chlorine water and hydrochloric acid be used, o'6 of gold is dissolved. If, instead of employing hydrochloric acid and chlorine gas, a mixture of sand, reduced gold, and peroxide of manganese, with hydrochloric acid, are placed in a bottle, 14 of gold is dissolved; so that it would appear that, under the influence of nascent chlorine, the gold is more readily dissolved than when the same gas is mixed in solution with hydrochloric acid previously to being placed in contact with the auriferous sand. Still these processes leave a great deal to be desired in a commercial point of view, as more than a third of the gold remains undissolved; and the same results are obtained if the chlorine gas be generated by another method, viz., by adding to the auriferous sand a mixture of chloride of sodium, sulphuric acid, and peroxide of manganese. Being convinced, therefore, that nascent chlorine gas was a fit and proper agent for cheaply extracting gold from ores, and that it was only necessary to modify the method of operating, I allowed the mixture of hydrochloric acid and peroxide of manganese, or of sulphuric acid, peroxide of manganese and chloride of sodium, to remain for twelve hours in contact with the auriferous sand; and then, instead of washing out the solution of gold, I added a small quantity of water, which removed a part of the acting agent, and this was made to percolate several times through the sand; by which method I succeeded in extracting from the sand, within a fraction, the whole of the gold. I then repeated the last experiments with natural auriferous quartz, and easily extracted the two ounces of gold per ton which it contained. I therefore propose the following plan for extracting the gold on a commercial scale :-The finely-reduced auriferous quartz should be intimately mixed with about 1 per cent. of peroxide of manganese; and if common salt be used, this material should be added at the same time as the manganese, in the proportion of three parts of salt to two of manganese. The whole should be then introduced into closed vats, having false bottoms, upon which is laid a quantity of small branches covered with straw, so as to prevent the reduced quartz from filling the holes in the false bottom. Muriatic acid should then be added if manganese alone is used, and diluted sulphuric acid if manganese and salt have been employed, and, after having left the whole in contact for twelve hours, water should be added so as to fill up the whole space between the false and true bottoms with fluid. This fluid should then be pumped up and allowed to percolate through the mass, and after this has been done several times the fluid should be run off into separate vats for extracting the gold and copper that may contain. To effect this, old iron is placed in it to precipitate the copper; and after this has been removed, the liquor is heated to drive away the excess of free chlorine, and a concentrated solution of sulphate of protoxide of iron, or green copperas, is added, which, acting on the gold solution, precipitates the gold in a metallic form. By this method both gold and copper are obtained in a marketable condition. If silver is present in the ore, a slight modification in the process will enable the operator to obtain this metal also. It is simply necessary to generate the chlorine of the vitriol, manganese, and chloride of sodium process, taking care to use an excess of salt, that is, six parts intead of three, as above directed. The purpose of this chloride of sodium being to hold in solution any chloride of silver that may have been formed by the action of chlorine on the silver ore, and to extract the metal, the following alteration in the mode of precipitation is necessary. Blades of copper must be placed in the saline solutions, to throw down the silver in a metallic form, then blades of iron to throw down the copper, the gold being then extracted as previously directed. I think the advantages of this process are, 1st, cheapness; 2nd, absence of injury to the health of the persons employed; 3rd, that not only is the metallic gold in the ore extracted (as is done by mercury), but it attacks and dissolves all gold which may be present in a combined state, besides enabling the miner also to extract what silver and copper the ore may contain. I cannot, however, conclude without reminding you of what is generally underrated- that is, the heavy expenses which attend the bringing of the ore to the surface, its crushing and preparation to render it in a proper state for being acted upon either by mercury or by any other agents. Second Report on the Application of Gun-Cotton to Warlike Purposes. By a COMMITTEE, consisting of W. Fairbairn, LL.D., F.R.S.; Joseph Whitworth, F.R.S.; James Nasmyth, C.E., F.R.A.S.; J. Scott Russell, C.E., F.R.S.; Jhn Anderson, C.E., and Sir W. G. Armstrong, C.B., LL.D., F.R.S., from Section G.; and J. H. Gladstone, Ph.D., F.R.S.; Professor W. A. Miller, M.D., F.R.S.; Professor E. Frankland, Ph.D., F.R.S.; and F. A. Abel, F.R.S., from Section B. YOUR Committee on the Application of Gun-Cotton to Warlike Purposes has simply to relate the circumstances that have taken the matter out of their hands. When the Committee was re-appointed at the Newcastle meet. ing, another recommendation relating to gun-cotton was passed by the Association-namely: "That it appears from the Report presented at this meeting by the joint committees of chemical and mechanical sections, and by the discussions which have followed its presentation, that the subject of gun-cotton is possibly one of very great interest and public importance; and that whilst the General Committee have taken measures to continue on their own account the inquiries which have been presented in the last year, they are sensible that the British Association does not possess means for its adequate examination; they are desirous, therefore, of drawing the attention of Her Majesty's Government to the importance of a full and searching inquiry, conducted by a Royal Commission, into the various practical applications connected with the public service, for which this material may be suitable, and that with this view the Assistant General Secretary be requested to cause Presented to the members of the British Association, Bath meet ing. Read before Section B. 162 On the Preparation of an Improved Wine of Iron. the Report, with its accompanying documents, to be printed with as little delay as possible, and copies presented (accompanied by the resolution) to the Right Hon. the Secretary of State for War, by a deputation consisting of the President and Officers of the Association, accompanied by the Presidents of Chemical and Mechanical Sections." In accordance with this resolution, as soon as the Report was printed, a copy was presented to Lord de Grey, at the War Office, by a deputation headed by General Sabine. This took place on December 11. Much interest on the subject was excited in many quarters, and a large number of the separate copies of the Report were asked for and circulated. In January the Government appointed-not a Royal Commission-but a Committee to investigate the subject in all its bearings. It consists of General Sabine as President, General Hay, Captain Brandreth, R.N., Commander Liddell, R.N., Colonel Boxer, R.A., Colonel Lovell, R.E., F. A. Abel, Esq., T. Sopwith, Esq., Professor W. A. Miller, Professor G. G. Stokes, and Dr. J. H. Gladstone, with Major Miller, R.A., as Secretary, representing thus-the army, the navy, military and civil engineering, as well as chemical and physical science, and comprising, as will be seen, three of the members of your Committee. The Messrs. Prentice, who were present at the Newcastle meeting, immediately established a manufacture of the article at Stowmarket, and which has furnished materials for many experiments on the use of gun-cotton for quarrying purposes. The Government Committee is already engaged in a systematic course of experiments relating to the manufacture and keeping qualities of guncotton, and its use in artillery, small arms, and engineering. Your Committee, therefore, consider that their work is accomplished, since the application of gun-cotton to military purposes is now in a fair way of being investigated with greater facilities and means than could have been at their disposal. After the above Report had been read, Professor Abel said the subject of gun-cotton had occupied a considerable share of his attention during the past year, and he would give an account of such experiments as had been made on behalf of Government. He was happy to say that they had made considerable progress already in their researches, and it afforded him still more pleasure to be able to say that results of those researches had been of a satisfactory character. He dwelt particularly upon this fact, because it would not have escaped notice that the official reports published in France were very unfavourable. The experiments conducted by Messrs. Prentice, and by himself, proved that gun-cotton possessed a great superiority over gunpowder, both in the simplicity and safety of its manufacture. The adoption of simple precautions set aside almost the possibility of accidents. With regard to a second point- the uniformity of manufacture-it was one upon which he had endeavoured to obtain the most precise information. He found that they might rely upon the Austrian system of manufacturc. The next, and most important branch of inquiry, in connexion with the properties and uses of gun-cotton, was the question of its permanence or stability. Its properties, as a material for military engineering, would be rendered nugatory if they could not place the most perfect reliance upon it. According to some persons they ought to place no reliance on gun-cotton, because it was liable to change and spontaneous decomposition. He had looked at the reports of the French chemists, and he was bound to say that, although those experiments had been conducted with great care by almost the highest authorities, he could not agree CHEMICAL NEWS, with them. He had at the present time a number of experiments in progress to ascertain the changes made by heat and exposure to light. Upon the occasion of this Report being read in the Mechanical Section, Mr. Scott Russell stated that General Hay, of the Hythe School of Musketry, had constructed a new form of cartridge suited for the Whitworth rifle; that he had found the use of gun-cotton was clean, and had not the disadvantage of fouling the gun; that it had much less recoil, although the effect was the same; that one-third of the weight of charge was the equivalent proportion, and that it did not heat the gun. He had seen a gun fired at a target with gun-cotton from the shoulder of the general at 500 yards. Twelve successive shots were all placed in a space one foot wide, by two feet high, and the value of the practice was measured by the fact that the mean radius of deviation from the centre was between nine and ten inches. Thus, therefore, the use of gun-cotton in musketry had been proved by English-made gun-cotton in English rifles by an English general, to perform all that the Committee last year reported of Austrian gun-cotton on the faith of the Austrian General Lenk. The next application made during the past year was to the driving of tunnels, shafts, and drifts in connexion with engineering applications. It was stated by the Committee that one-sixth of the weight of charge of cotton was equal in blasting effect to gunpowder, and this had been proved in practice in a number of instances. At Wingerworth colliery one-thirteenth of the weight of gun-cotton as compared to gunpowder; in the slate quarries of Llanberis, at Allen Heads, one-seventh was required. At Allen Heads, at some lead mines, a canal was being driven seven miles long. The drift was seven feet by five in the hardest limestone. Both ends were worked by gun-cotton fired by an electric battery. The great advantage experienced was that the air was not contaminated by smoke, and that the work could be carried on more rapidly. The next application had been made to the detaching of large masses of rock. This had been tried in several places, and it was found that one pound of gun-cotton was able to detach from thirty to sixty tons of rock. The Government appointed a committee, naval, military, and civil engineering as well as chemical and physical science, and that committee was already engaged in a systematical course of experiments relating to the manufacture and keeping qualities of gun-cotton, and its use in artillery, small arms, and engineering. PHARMACY, TOXICOLOGY, &c. On the Preparation of an Improved Wine of Iron, Ammonio-citrate of Iron. 60 The wine thus prepared was perfectly transparent, and had no disagreeable taste. * Read at the meeting of the British Pharmaceutical Conference. CHEMICAL NEWS, Oct. 1, 1864. New Method of Detecting Arsenic, &c., in Mixed Gas. On the Amount of Alkaloid in Commercial Citrate of Iron and Quinine, by Mr. J. C. BRAITHWAITE.* THE author had examined fifteen samples of this medicine, which should contain 16 per cent. of quinine, or about 25 per cent. of citrate of quinine. The following is a tabular form of his results : DR. HERAPATH having to investigate a case of suspected poisoning by phosphorus, in which the traces of free phosphorus had disappeared, during the long interval between administration of the poison and analysis, he examined for phosphorous acid by Scherer's method, but as several of the hydrogen compounds of sulphur and arsenic, for instance, have the property of blackening the salt of silver, he eliminated these hydrogen compounds from the gas before its absorption by ammoniacal nitrate of silver, or tested the gas as it was being evolved from any of their compounds. Dr. Herapath dissolved the organic matter, stomach, intestines, and contents in dilute hydrochloric acid by heat. The room of operation being at the time quite dark, an apparatus was fixed for exhibiting any phosphoric flashes of light, as in Mitscherlich's experiment: no flashes appeared. The acid solution might, however, have contained arsenic, phosphorus as phosphorous acid, antimony as chloride, and sulphur as taurine, &c. No chlorate of potassa could be employed in oxidising the organic matter, as phosphorous acid would become phosphoric, and all evidence be lost, for sulphates and phosphates are not reducible in the hydrogen apparatus; to the liquid filtered there was added one-third of spirit of wine, and it was then ready A gas evolution bottle with funnel and pipe, armed with a tube containing chloride of calcium, and chalk in coarse powder, for the preparation of pure hydrogen gas, was got ready and tested, as usual, for arsenic. To the exit lamp was attached a green glass tube, well supported, passing over two or three spiritlamp fumes. The exit pipe was bent at right angles, to go through a wide-mouthed bottle, containing slips of white filtering paper, dipped in a solution of nitroprusside of sodium, made alkaline by ammonia, from which the gas was carried to the next bottle, containing ammoniacal nitrate of silver; and there was another exit tube leading to a bottle of some salt of lead, or this may be replaced by a jet for burning for use. 163 the gas. The apparatus being at this period ready for use, pure zinc sulphuric acid and distilled water the stream of gas allowed to escape through the were placed in the hydrogen evolution bottle, and apparatus, heat being applied to the tubes with spiritlamps. Now, if arsenic had been present it should have produced a crust in the usual place, and antimony would, if present, have been deposited at a spot near it. Whilst sulphur would partly have been sublimed and deposited in front of the arsenic, and the remaining undecomposed sulphuretted hydrogen gas would have communicated a deep purple blue tint to the paper charged with the ammoniacal nitro-prusside of sodium. Whilst the phosphoretted hydrogen, passing unchanged through all these tests, would have been at once seized by the ammoniacal nitrate of silver, and have produced the black phosphide of silver, whilst the hydrogen escaped through the lead solution without changing its colour, unless the evolution (supposing phosphorus to be present), of phosphoretted hydrogen would have been too violent for the perfect reaction of the silver salt. It was now possible to examine the prepared organic liquid with this apparatus, by inserting it in quantities of only a few drachms at a time into the hydrogen bottle, through the tubulated funnel, and by employing sufficient spirit, no frothing took place to endanger the success of the experiment, but should it occur it could at any moment be checked by the addition of a little spirit down the funnel. Did the tubes show no deposit, and if the paper remained white, neither arsenic, antimony, nor sulphur could be present. The black precipitate in the silver bottle would inferentially have been phosphide of silver, but it admitted of absolute proof by testing with Scherer's process. The operation being completed, the silver salt was passed through a filter previously washed with acetic or nitric acid, and afterwards with ammonia, and the collected black precipitate submitted to proof by burning the filter paper, acting on the ashes with nitric acid and heat until oxidised, the silver precipitated by pure hydrochloric acid, and the solution filtered. It contained all the phosphorus as phosphoric acid, which could be tested by the nitrate or chloride magnesium with ammonia, whilst the characteristic crystals of triple phosphate ammonia and magnesia should be examined in the microscope and identified by the action of polarised light and by the measurement of their angles in the goniometer, or the phosphoric acid may be tested by a solution of nitrate of silver with ammonia, when the yellow phosphate of silver would be obtained, and the blue phosphate of iron with a solution of its proto-salt. An objection might be raised to the testing of the ashes of a filter, as the fibres of paper might contain phosphate, which an acid washing would not remove, but which could be found after incineration by the same method. It was, therefore, better to burn the phosphoretted hydrogen, and condense the phosphoric acid vapour, and test the liquid for that acid by the above method. A single drop of dilute solution of phosphorus and phosphoric acids furnished abundant evidence of crystals of the ammonia and magnesium salt when a glass slide with a drop of distilled water on it had been inverted for a few seconds over its flame. When combustion of the gas is to be the method of proof, the silver solution should be removed to a small hard glass jet inserted in the end of the tube from the ammoniacal nitro-prusside of sodium bottle; the gas being inflamed may be treated as above, but to get suffibe well to burn the gas in a glass globe, kept cool by cient evidence of minute traces of phosphorus it would damp cloths round it, and the issuing stream of gas passed through a perpendicular tube surrounded by a freezing mixture, and the condensed water collected in a bottle by Mitscherlich's process, then by washing out the bottle, tube, and globe with distilled water, and concentrating by evaporation, it may be tested as before. PROCEEDINGS OF SOCIETIES. CANTOR LECTURES. OHEMICAL NEWS, coal and brought into immediate contact with the oxygen of the atmosphere also contained in the pores of the charcoal, while oxidising or destroying the products of putrefaction converts them into water, carbonic acid, nitric acid, &c. These important scientific observations of Dr. Stenhouse have already received practical application. Thus Mr. Haywood has established charcoal filters at the mouths of public drains, thereby arresting the escape and diffusion in the atmosphere of the noxious effluvia given off by the putrefying matters in the sewers. Further, charcoal respirators have become extensively used since Dr. Stenhouse called public attention to the valuable properties of this "On Chemistry Applied to the Arts." By Dr. F. CRACE substance; and lastly, atmospheric filters, containing CALVERT, F.R.S., F.C.S. LECTURE VI. DELIVERED ON THURSDAY EVENING, APRIL 28, 1864. Animal black, Flesh, its chief constituents, boiling and roasting. its manufacture and applications. Various methods of preserving animal matters. Employment of animal refuse in the manufacture of prussiate of potash. A few words on the decay of organic matters, and their fermentation and putrefaction. (Continued from page 129.) charcoal, have been successfully applied in the Houses of Parliament to purify the entering air from any noxious gases it may contain before passing into the building. The natural decay or destruction of organic matters is due to two perfectly distinct causes-one of them chemical and the other physiological. The former has been investigated by many of the most eminent chemists of the day, and no doubt can remain that the action of the oxygen of the atmosphere converts the carbon of organic substances into carbonic acid, the hydrogen into water, the sulphur into sulphuric acid, the nitrogen into nitric acid, the phosphorus into phosphoric acid, &c. Much light has recently been thrown upon these phenomena by M. Kuhlmann, who clearly shows that the oxides of iron play a most important part therein; thus that the sesquioxide of iron yields its oxygen to the elements of the organic matters; that the protoxide of iron thereby formed absorbs oxygen from the air, which reconverts it into sesquioxide, and this again yields its oxygen to a fresh portion of organic matter, so that sesquioxide of iron is a most powerful oxidising agent, it being, in fact, the condenser of oxygen and the medium of its conveyance to and destruction of organic substances. MM. Chevreul and Kuhlmann have also shown that sulphate of lime acts in a similar mannernamely, that it yields its oxygen to the elements of organic substances, and is thus converted into sulphuret of cal I SHALL now examine with you some of the various causes which contribute to the destruction of animal matters, when it arises from slow decay or putrefaction. The first of these to which I shall have the pleasure of calling your attention is that observed by Dr. Stenhouse, who, in 1854, made the curious discovery that, if the body of an animal was buried in a carbonaceous mass, such as charcoal, after a few months the whole of the animal, excepting the skeleton, would entirely disappear; and what was still more remarkable was that, though the experiments were conducted within his laboratory, no unpleasant effluvia were apparent to those who were constantly there. This eminent chemist attributed the rapid and complete destruction of animal tissue in these experiments to the oxidation of the animal matters by the oxygen of the atmosphere; but to enable you fully to understand how this occurs, I must call your attention to the follow-cium, which having a great affinity for oxygen, is again ing facts:-Lowitz, many years since, observed that charcoal possesses the property of absorbing and condensing in its pores large quantities of various gases, and Theodore de Saussure made an extensive series of experiments, from which I extract the following data: One cubic inch of boxwood charcoal absorbed of- Hydrochloric acid Sulphurous acid Sulphuretted hydrogen 85 65 Nitrogen Consequently the absorption or condensation of a gas in charcoal appears to be in ratio to the solubility of the gas in water, and although the condensation by a solid and by a liquid may at first appear necessarily due to different causes, and therefore to bear no relation to each other, yet in my opinion these two actions are identical. Seeing that the gas is condensed by the molecular attraction of the solid, I do not see why the same attraction should not be exercised by the molecules of the liquid. The different degrees of solubility of various gases are no doubt owing to their respective physical properties, such as specific gravity, repulsive or expansive forces of their molecules, &c. I may here mention that I am now engaged in a series of experiments, in the hope of throwing some light on this interesting question. Gay-Lussac, in his researches on the condensation of gases by charcoal, found that one gas may expel and take the place of another gas already condensed in the charcoal; and Dr. Stenhouse, following up this observation, states that the gases, vapours, and sporules generated by the putrefaction of animal substances are absorbed by char rapidly converted into sulphate of lime, and thus the oxygenation and destruction of the organic matter is effected. Mr. Millon has published an interesting paper on the formation of nitre, or nitrate of potash, through the ammonia generated during the destruction of organic substances being oxidised into nitric acid, which combines with potash, if present, and if not with lime or magnesia, which are present in all soils. Mr. Millon has remarked that this important chemical reaction is effected by an organic substance called humic acid, which acid, or its homologues, exists in large quantities in all earthly loams containing much organic, and more especially vegetable, matters in a state of decomposition. Humic acid absorbs the oxygen of the atmosphere, which oxidises the ammonia into nitric acid and water. The chemical theory of the destruction of organic matters through oxidation and their absorption of plants and re-conversion into the same substances from which they were derived, such as sugar, starch, gum, oil, essences, &c., or albumen, fibrine, gluten, caseine, &c., was greatly in favour a few years since, as it appeared to fulfil all the requirements of nature. It has, however, been greatly shaken by the beautiful researches of M. Pasteur on feimentation, putrefaction, and spontaneous generation, which proves clearly that these physiological actions play a most active part in the destruction of organic substances. This most skilful chemist has demonstrated that there is no such thing as spontaneous generation, and that the notion entertained by some physiologists, that if matter is placed in favourable circumstances as to heat, light, &c., and in a proper medium, it will become spontaneously animated, is undoubtedly erroneous, and that life in all instances proceeds from a germ or egg in which the vital principle is implanted by the Creator. He proves that life, even in the most insignificant of microscopic creatures, always originates thus, and that there is no single instance of matter being animated by purely physical causes. Let me draw your attention to a few among many facts observed by M. Pasteur, proving that life is not a property of matter, like weight, elasticity, compressibility, &c., but is always the result of a germ even in its lowest development. When arterial blood is carefully introduced from the artery into a clean vessel, and there brought into contact with oxygen, no fermentation or putrefaction of the blood ensues; and if the experiment is repeated, substituting for the chemically-prepared oxygen atmospheric air which has been passed through a tube containing pumice-stone and carried to intense heat, in this case also there is no putrefaction or fermentation; but if ordinary atmospheric air be used in the place of pure oxygen, or heated air, and left in contact with some of the same blood, this vital fluid will rapidly putrefy, which is doubtless owing to the presence in the atmospheric air of the sporules or eggs of micoderma and vibrios, or organised ferments, which give rise to the various chemical phenomena and changes of organic matters into products which characterise fermentation and putrefaction. The same results are obtained when fresh urine is substituted for blood, an important fact, proving that the germs of fermentation do not exist in the fluids themselves, and that fermentation does not proceed from any molecular or chemical change in the composition or nature of the organic substances contained in blood and urine, but that the ferment from which these phenomena proceed is to be sought for in the atmosphere. I shall substantiate this view by several other interesting observations made by M. Pasteur. If some asbestos is heated to a red heat and plunged into a liquor susceptible of putrefaction, such as a saccharine liquor, no fermentation ensues; but if atmospheric air is passed through asbestos at natural temperature, and the latter then immersed in a similar solution of sugar, active fermentation soon takes place, proving that the atmospheric air has left on the surface of the asbestos sporules of the mycoderma vini, which being introduced with the asbestos into the saccharine fluid, originated the well-known alcoholic fermentation. Another beautiful series of experiments by M. Pasteur is the following:-He introduced into 60 small balloons a small quantity of a highly putrescible fluid, and after boiling the fluid in order to drive out the remaining air in the balloons by the formation of steam, he closed the small apertures, so that on cooling the steam condensed and a vacuum was produced. He then proceeded to open 20 of these balloons at the foot of one of the hills of the Coté d'Or, 20 others at the summit of the same (about 2000 feet high, and the remaining 20 at a point near Chamounix, and the following results were observed :-Of the first 20 balloons the contents of 15 entered into putrefaction within a few days; of the second 20 only 6; and of the third 20 only 2 gave signs of fermentation. These results, as well as some others published by M. Pasteur, prove that the sporules or germs of putrefaction and fermentation exist in all parts of the atmosphere, but more abundantly in the lower strata, which are necessarily in contact with great quantities of organic matter in a state of decay, and that these sporules become scarce in the upper regions, which are further removed from the source of pollution. Further, he has proved, as I stated in my last lecture, when speaking of the preservation of milk, that fluids extremely liable to fermentation or putrefaction may be prevented from entering into those conditions by heating them to 250° or 260°, a temperature at which the sporules cannot resist decomposition in the presence of water. M. Pasteur has advanced a step further in this interesting inquiry, for he has demonstrated that there are two distinct phases in putrefaction. In the first there are the vibrios produced in the bulk of the fluid containing animal matters in solution, and these microscopic animals unfold the organic substances into more simple compounds; in the second phase, there are produced on the surface of the fluid cryptogams, which he calls mycoderms, and which absorb oxygen from the air, and cxidise the products developed by the vibrios. In the case of the fermentation of vegetable substances, such as saccharine matters, there are mycoderms (Mycoderma vini), which unfold them into, say alcohol and carbonic acid, while other mycoderms (Mycoderma aceti) are produced, and grow on the surface of the fluid, oxidising the alcohol into water and acetic acid. He therefore concludes that the animal vibrios and vegetable mycoderms exist abundantly in nature, and that they must be and are the most active causes of the destruction of vegetable and animal substances which have fulfilled their vital function on the earth, reducing them into water, carbonic acid, ammonia, sulphuretted hydrogen, &c., which, in their turn, become the foods of a succeeding generation of plants and animals. We may therefore truly say that death is life in the constantly reviving world. M. Pasteur has observed another most curious fact connected with these microscopic beings-(I say microscopic, because it requires a most powerful instrument and high powers to distinguish them, and to ascertain that vibrios possess a vibratory motion while mycoderms are stationary) this is, that vibrios are the only animals which can live in pure carbonic acid, and which are killed by oxygen even diluted with another gas. Oxygen is essential to the life of mycoderms, and some of them can also exist in carbonic acid. Lastly, M. Pasteur has noticed that if a very small amount of yeast is added to a saccharine fluid, the yeast will not materially increase in quantity, because the new generation which is produced lives on the remains of its parents; but if phosphate of ammonium or of lime and some sal ammoniac is added with the yeast, the latter will rapidly increase and occupy several times its original bulk. It is curious to observe that these microscopic cryptogams require the same kind of food as man. Thus they require nitrogenated food-so do we. They require mineral food, as phosphates-so do we. They require respiratory food -so do we. They produce carbonic acid as part of their vital functions-so do we. I cannot do better than conclude this part of my subject by giving the following table descriptive of the various ferments observed by M. Pasteur:FERMENTATION. Mycoderma vini. Mycoderma aceti. Alcohol. Oxidises Acetic. alcohol. Water. PUTREFACTION. Infusorial Ferments. Vibrios, unfold animal substances. Bacteria, oxidises organic matters of an animal origin. I should mislead you, however, if I did not call your attention to another class of fermentations, which are chemical in their nature and in their action. This, for example, is the case when bitter almonds are crushed and mixed with water. The amygdaline they contain is decomposed into prussic acid, hydruret of benzoil, &c., by the ferment they contain, which is called emulcine. Again, when black mustard is reduced to meal, and placed in contact with water, the myronic acid it contains is decomposed into the essential oil of mustard, a most corrosive fluid, and this is also effected by a special ferment called myrosine. Again, when malt is mashed with water of a temperature of 170°, its starch is converted into sugar by a ferment called diastase. We also know that the starch which we take into our stomachs as food is converted into sugar by animal diastase, which exists in the saliva as well as in the pancreatic juice, and that this conversion is identical with that which takes place in the mashtub. In |