The second purpose which liquids fulfil in the human system is to remove from the blood those various substances which have been acted upon by the atmosphere, as above explained, or others which have been produced by | the action of vitality, and which require also to be removed from the system to enable it to be in a normal state. Again,-Man requires various mineral matters, but these must be of a peculiar nature, so as to render them fit to fulfil in the organism the different functions to which they are adapted. Thus we find that man requires soda, potash, lime, manganese, iron, chlorine, sulphuric acid, phosphoric acid, and other mineral elements of minor importance. No doubt that for man, as for plants, the nature and the relative proportions of the mineral matters entering into the food which he takes are most essential; for if in that food a sufficient amount of salts of soda were not present, one of the essential elements of blood would be wanting. If phosphate of lime is not supplied in due proportions, the frame-work of his body will suffer. The same may be said of the importance of carbonate of lime in the water which he takes as a beverage; and, therefore, it is yet a question to be solved by experience, whether the extremely pure water which is now introduced into several of our principal cities, such as Manchester, Glasgow, &c, so agreeable to the general feelings of the public, under the impression that it is pure water, and which confers such benefits on manufactures in general, will not, in course of time, prove detrimental to the health of the inhabitants, owing to its extreme purity, not containing carbonate of lime, which is so essential to the formation of bone in man and animals.

The fourth class of food that man requires may be called heat-producing or respiratory food. This food is chiefly assimilated and employed by him to maintain the heat of the body, through the action of the oxygen of the atmosphere, and which, being dissolved by the blood, circulates with it, and burns or oxidises its carbon, converting it into carbonic acid. This class of food is mainly represented by starches, gums, sugars, oils, fatty matters, and several other substances, such as pectic acid, pectose, &c. The fifth class of food is flesh or blood-forming food, which is employed in the system to replace the various animal tissues which have fulfilled their functions, and which are modified and altered by the action of the oxygen of the atmosphere as above explained, or are destroyed by the tear and wear of life, and which leave the system principally in some modified state, by means of the fluid taken as a beverage. This class of food is represented by fibrine, albumen, caseine, and other similar nitrogenated substances, which we find compose in a great measure flesh, blood, milk, and other similar foods.

As it is impossible for me, in the course of one lecture, to give you a correct idea of the chemical phenomena involved in the digestion of the five various classes of food to which I have referred, I must confine my observations to the digestion of the two last classes of food,-namely, the heat-producing foods, and the flesh or blood-forming ones. The blending of chemistry with animal physiology has thrown much light on the phenomena of digestion; in fact, until chemistry had investigated many of the actions which take place in the digestion of foods, much obscurity existed, and many empirical views were promulgated on these important and essential functions of life. But since chemistry has penetrated into this branch of science, it has brought to light many facts which could not be understood or satisfactorily explained until the chemical facts connected with digestion had been well studied, and much light thrown on the complicated phenomena.

Although I do not agree in the opinion entertained by some persons that the phenomena of digestion are purely due to chemical actions, on the other hand, I am of opinion that they cannot be regarded as entirely due to the force called vitality. My opinion is that the phenomena of

digestion are due to the simultaneous or successive actions of vital and chemical forces. Thus, for example, the secretion of the various fluids necessary for digestion is due to vitality, and the influence of the fluids secreted on the substances taken as foods is due to chemical action, or, in many instances, to actions not yet well understood, but which still come under the head of chemistry-namely, purely chemical fermentation. I understand by this term the peculiar conversion or unfolding which certain substances undergo by the presence or contact of minute quantities of other substances, such, for example, as the conversion of starch into dextrine and sugar under the action of the peculiar ferment called diastase, or the unfolding of amygdaline into hyduret of benzoil, prussic acid, &c., under the influence of a ferment called emaulsine. But we must bear in mind that this class of fermentations are perfectly distinct from those which I described to you in the last lecture of my course delivered in 1864, which fermentations referred to those which are determined or produced in consequence of the development in the fluids of certain microscopic vegetables or animals which, by their peculiar mode of growth or life, determined the changes which are observed in many vegetable and animal fluids when in a state of fermentation or putrefaction.

With these explanations I shall now proceed to state that there are five principal fluids which are essential to digestion, and which are secreted by various organs which participate in the actions which take place during digestion, and these are:-1. Saliva, which is secreted by certain glands in the mouth; 2. Gastric juice secreted by the membranes of the stomach; 3, Pancreatic juice, secreted by a gland situated just beyond the outlet of the stomach; 4, Bile, secreted by the liver; 5, a Gaseous medium, called atmospheric air.

Let us now examine how and to what degree each of these fluids acts upon the two special classes, and which I have stated are blood and heat-forming foods.

ANIMAL FOOD.-When meat, for example, is taken as a means of subsistence, although it is divided into small pieces by mastication, and gradually brought into the form of a ball, so as to pass with facility from the mouth into the stomach, still it undergoes no chemical change by the mixing or imbibition of the saliva. But when it arrives in the stomach, it meets here a very acrid fluid called gastric juice, the acidity of which is due, not to hydrochloric or acetic acids, as was formally stated, and which are now attributed to indigestion, but to the presence of phosphate and lactate of lime, together with a little free lactic acid, which acid elements are essential not only to the action of the. ferment called pepsine, but also facilitates its solution. This pepsine acts in a most remarkable manner, for a minute trace of it appears to have the power to liquefy, if I may so express myself, the solid substance called fibrine, and to alter its conditions. In fact, all the solid animal elements of food become fluid under the action of the gastric juice, and are transformed into the fluid mass which has received the name of albuminose or pectose. The animal matter so transformed is susceptible of being absorbed either by endosmosis or diffusion by the coats of the stomach; but the greatest part of it passes on into the small intestines, where it meets the bile, and where the acidity of the fluid is neutralised and it becomes alkaline owing to the alkaline state of the bile. This transformation of the acidity of the gastric juice into an alkaline character, is essentially owing to the fact that during its passage through the small intestines it is in a fit state to be absorbed by the mucus which coats those vessels of the human organism, and to come in contact with the blood, which is always in an alkaline condition. Further, we know that organic matter in an alkaline condition enters more rapidly into decay and decomposition, so that it is thus in a fit state to be rejected by the body. There

Here I must pause in my description of digestion to make you acquainted with some of the recent discoveries which tend to prove that gastric juice does not simply liquefy fibrine and caseine, but that it acts also on albumen in such a way as to modify its molecular condition, and thereby its chemical properties. If the albumen of an egg be injected into the jugular vein it passes unaltered to the blood, for it is found in the secretions of the kidneys. It follows that albumen of the egg must undergo a molecular change to render it fit to become assimilated, and we may assume, therefore, that it experiences the same change in the stomach under the influence of the ferment, called pepsine. But I cannot conclude this part of my subject without calling your attention to some interesting researches lately published by Mr. Smee. Until the publication of those researches, although scientific men had assumed that there must be an identity between albumen, fibrine, and caseine, which are the chief elements representing animal food, still they had not been able to demonstrate their convertibility one into the other. Now, Mr. Smee has accomplished that fact; or, in other words, has reversed the theory previously entertained as to what takes place during digestion; for he has established that fibrine, or the clot of blood; caseine, or the curd of milk; and albumen, the serum of blood, are convertible into one fluid, which he has called albumenose, or pectose. Mr. Smee has succeeded, I say, in reversing the problem, and has shown that albumen may be converted into fibrine, and probably caseine. To effect this interesting change he proceeds as follows:He passes a current of pure oxygen gas through a solution of albumen of blood or egg, slightly acidulated with acetic acid, and at a temperature of blood heat, or of 98° to 100°, and after several hours a mass of fibrine appears, the production of which is facilitated by bringing into play the action of an electric current. If instead of an acid solution of albumen, Mr. Smee employed a weak alkaline solution of the same substance, it became transformed into a peculiar substance which I described to you in my last year's lecture, under the name of chondine. But I would strongly recommend to all lovers of animal physiology to read the interesting papers which have been published by that gentleman in the Proceedings of the Royal Society, 1864 and 1865.

:

FATTY MATTERS.-Allow me now to have the pleasure of calling your attention to the modifications which fatty matters have to undergo when taken into the human system, before they are prepared for assimilation. Most physiologists maintain, at the present day, that these substances undergo a change during their retention in the mouth or their passage into the stomach, but Dr. Marcet is of opinion that fatty matters undergo a certain modification during their passage from the mouth to the entrance of the small intestines. At all events, there can be no doubt, from the researches of some of the most eminent physiologists, that fatty matters undergo a most important change when they arrive in contact with the fluids secreted by the gland called the pancreas, which transforms them into an emulsion, but does not saponify them. The matters so emulsioned are then further acted upon by the bile, and finally are absorbed by the lacteal vessels, and carried into the circulation of the blood. It is the absorption of fatty matters by the lacteal vessels which deceived the physiologists of an earlier date, and led them to believe that that white substance was the absorption of the nutrient parts of food, to which they gave the name of chyle, and which, according to them, gradually became transformed into the clement of blood. Fatty matters so absorbed and carried into the torrent of the circulation of the blood

oxidation of the oxygen contained in the air inspired, and thus they help to maintain the heat of the human body, or they are stored up with the view of supplying the elements necessary to the maintenance of the heat of the body, when, through disease, the body has ceased to take its ordinary external nourishment. In fact, we may consider these fatty matters to be to the body what the coal fields of England are to its manufacturers.

Another division of the heat-forming or respiratory foods is that to which I have already referred, and which includes starch, gum, and sugar, and the transformations which these peculiar substances, and especially starch, undergo in order to become assimilated. Allow me to claim your undivided attention to the facts which I am now going to bring forward. When bread, potatoes, or any amylaceous substance, arrives in the mouth, it gradually becomes mixed and saturated with saliva1st, the saliva of mastication, which is secreted by the parotid glands, and serves only to coat the mass of food called the ball, and so facilitate its passage into the stomach; 2nd, the saliva which is secreted by the submaxillary glands, a thin, watery fluid, which acts chemically on the food, converting the insoluble starch into soluble elements called dextrine and sugar. The amylaceous substance thus acted on passes into the stomach without further action, but when it arrives in contact with the fluid secreted by the pancreatic glands, there it undergoes a complete change; for the pancreatic fluid, called by the Germans the intestinal saliva, completes the conversion into dextrine and sugar of such portions of the starch as have not been acted on by the saliva of the mouth. For both these fluids are alkaline-I mean the pancreatic fluid and the saliva from the sub-maxillary glands; for that secreted by the parotid glands is acid, and this explains why the saliva is always acid in the morning, or before man has taken food. I say that these fluids are alkaline, and they contain a ferment called diastase-a ferment identical with that which exists in malt, and which converts in the brewer's vat his mash into a saccharine fluid, which ultimately becomes beer. The starch so converted into dextrine and sugar through the action of the diastase of the saliva and of pancreatic fluid, is absorbed by the mucus of the small intestines, and conveyed by the small veins which line those organs into the vena porta, and thence into the liver. This important organ fulfils several functions. First, it secretes bile, an alkaline fluid, which, as we have seen, acts as a neutraliser of the acid fluids arriving from the stomach, converting them into an alkaline condition fit for decay. Secondly, it is an eliminating organ, for the bile appears to contain some of the elements which require to be removed from the blood, and which have been produced through the wear and tear of life. Further, it contains some of the elements of the colouring matter of blood, for the colour' of bile and that of the blood appear to have a resemblance. But the most important substance which the liver contains is a peculiar. ferment, discovered by M. Claude de Bernard, which has the power to transform the insoluble substance which he calls glycogen into a soluble one, namely, sugar. Thus, it would appear, from the researches of that eminent physiologist, that the amylaceous substances absorbed as food, and acted on as above explained, arrive by the vena porta in the liver, and there are stored until required by man to maintain the heat of his body and the phenomena of life. He has observed - and the results at which he has arrived have been confirmed by C. G. Lehmann, another eminent physiologist-that there is comparatively only a small amount of sugar in the blood when it passes into the liver by the vena porta, whilst the same blood, when it leaves the liver by the hepatic veins, contains a comparatively large quantity. Thus, Lehmann has found that the quantity of sugar in the vena porta blood amounts to

nection here with, allow me to state that Lehmann has published the following data respecting the action of the liver on the various elements contained in the blood. He has found that there is much more fibrine in the vena porta than in the hepatic veins; that albumen is more abundant in the portal than in the hepatic veins; that fatty matters are in larger quantities in the portal than in the hepatic; that globullin, or the substance which represents the globules of blood, is in less quantity in the portal than in the hepatic; whilst the colouring matter, called hematozine, is in larger quantities in the portal than in the hepatic. This, according to Lehmann, explains why we find colouring matters in bile, which may be considered as modifications of the one existing in blood, and which are found only in that fluid.

The curious substance called glycogen by Claude de Bernard, was extracted by him from liver, by the following process:-The liver of an animal recently killed was cut into thin slices and thrown into a small quantity of boiling water. The whole was allowed to boil for an hour, and was then submitted to pressure. A small quantity of fluid was obtained, which, when treated by alcohol, yielded a white flocculent precipitate, and this, when re-dissolved in water, and re-precipitated by alcohol, was then found to yield with iodine and other re-agents the characteristic properties of amylaceous substances. Although glycogen exists in larger quantities in the liver when man or an animal takes a large quantity of amylaceous substances as a part of food, still this substance is found in the livers of carnivorous animals, showing that under the force called vitality animal matters are susceptible of undergoing the chemical change which converts them into a substance similar to starch. But this glycogen gradually disappears from the blood as it passes from the hepatic veins into the heart, and lastly through the torrent of circulation, for the oxygen of the atmosphere rushes into the lungs by inspiration, gets into contact with the blood in the numberless cells composing them, and by its action upon the glycogen helps to convert it into water and carbonic acid gas, which are thrown out by expiration. Now, although this conversion of the glycogen proceeds during the whole of the circulation of the blood, still there can be no doubt that the greatest portion of it is converted into gaseous elements when it comes in contact with the oxygen of the air in the cellular tissues of the lungs, for much less oxygen is found in arterial blood than in that of the hepatic veins.

To smooth the pathway of the reader to the perfect understanding of the above statement, it is perhaps necessary to add that when the blood leaves the liver it travels through the hepatic veins into the right ventricle of the heart; that by the contraction of that organ the venous blood is thrust into the lungs, where it comes in contact with the oxygen of the atmosphere, and is converted from the dark purple colour which characterises venous blood into a brilliant red-coloured fluid, called arterial blood. Having undergone that change, it runs thence into the left ventricle of the heart, and, having filled it, that organ contracts itself, and drives the blood with great force through the whole of the arterial system, and during its passage through the capillary vessels it gets converted gradually into venous blood, which reaches through the various veins the vena porta, and this conveys it to the liver. Thus, we can perceive how the blood constantly flows in a circular motion through the whole of the human system. At all events, before proceeding with the few remarks I have to offer on respiration, and calling atten

(To be continued.)

ACADEMY OF SCIENCES.
November 27, 1865.

DOEз ozone exist in the atmosphere? That is the question asked by Admiral Berigny, who, having patiently made what he conceived to be ozonometric observations for the last ten years, and after having assisted M. le Verrier in selecting stations for similar observations all over Paris and in every department of France, has been brought at last to doubt whether the observations are good for anything; so he beseeches the Academy to appoint a commission to settle definitively,-1, whether ozone exists in the atmosphere; 2, whether Schönbein's or anybody else's papers prove the presence of electrised oxygen; and, lastly, whether an easy and reliable method of detecting it could not be devised. The Academy appointed a commission composed of Chevreul, Dumas, Pelouze, Pouillet, Boussingault, Le Verrier, Valliant, Frémy, and E. Becquerel, whose report will not doubt scatter popular notions on atmospheric ozone to the winds.

To say the truth, the evidence in favour of the presence of ozone in the atmosphere is, as M. Frémy showed to the Academy, of the most doubtful character. M. Frémy said that he knew of only one certain test for ozone in the air, and that was the oxidation of silver, by passing a current of moist air over the metal; and this test he had applied many times without obtaining any indication of ozone. We are very far from being acquainted, he said, with all the bodies held in suspension in the air, and, consequently, ignorant of the action they may exert on iodide of potassium. May not, he asked, this salt become alkaline, or set free iodine under other influences besides that of ozone? He did not deny the fact of its presence, but he asked a positive proof of it. Such a proof is required; for seeing that ozone is instantly destroyed by organic matters, and absorbed by nitrogen, it is difficult to understand how such a body can continue to exist in the air, which contains precisely the elements which would at once change the ozone. As regarded the test-papers, he asked, what use there could be in a re agent which was affected not only by ozone, but by the oxygen compounds of nitrogen, by oxygenated water, by ammonia, by formic acid, by essential oils, by the acid products of combustion, by dusts, in a word, by all sorts of things which are held in suspension in the air.

M. Soret presented a note entitled "Researches on the Density of Ozone." Our actual knowledge of the volumetric relations of oxygen is limited to the following facts: -1, that ordinary oxygen diminishes in volume when a part is converted into ozone; 2, that when ozonised oxygen is treated with iodide of potassium or other oxidisable matter, the ozone disappears without any alteration in the volume of the gas; and, 3, that under the influence of heat ozonised oxygen undergoes an expansion equal to the volume that the part absorbable by iodide of potas

memoir, "On the Utilisation of Soda Waste and Chlorine Residues." Of this second paper we shall immediately give as full an abstract as is necessary after the author's letters which have appeared in our pages.

M. A. Keller communicated to the Society some Remarks on a note by MM. Moutier and Dietzenbacher "On a New Property of Sulphur." Our readers will remember that these gentlemen stated that sulphur could be rendered soft and plastic by fusing it with a trace of iodine or some paraffine, lamp black, &c. M. Keller has tried every one of the substances named, but has never succeeded in producing the result stated, unless he poured the sulphur either into cold water or in a very thin layer on a very cold porcelain tile, under which circumstances sulphur alone is always made soft and plastic.

In the abstracts of foreign memoirs we find a few novelties, which will have a place in our columns.

NOTICES OF PATENTS.

provements in the manufacture of anti-inflammable starch." July 26, 1865.

2040. A. Millochan, New York, U.S. A., " An improvement in stills for the distillation of petroleum and other oily substances."-August 5, 1865.

2903. W. E. Newton, Chancery Lane, "Improvements in making amalgams or alloys of metals." A communication from H. Wurtz, New York, U.S.A.—Nov. 11, 1865.

CORRESPONDENCE.

Continental Science.

PARIS, November 30.

ON resuming my letters, it is most disagreeable to find that the first thing which I think demands notice is some correspondence from England, published in Cosmos, which reflects no credit on one of the parties concerned. There is no necessity for the suppression of names, so I may state plainly that in relating the poisoning of the two

SIX MONTHS.

Communicated by Mr. VAUGHAN, PATENT AGENT, 54, Chancery Lane, W.C.

2106. J. H. Johnson, Lincoln's Inn Fields, Middlesex, "Improvements in the preparation or production of spongy metals, and in their applications."-A communication from F. Drivet, Turin, Italy.-Petition recorded August 15, 1865.

2482. C. H. L. Wintzer, Osnabrück, Hanover, "Improvements in separating phosphorus from iron and other metals in metallurgical processes."-Sept. 27, 1865.

2682. W. Beardmore, Parkhead, Lanark, N.B., "Improvements in furnaces."-Oct. 17, 1865. 2870. F. Prange, Liverpool, "Improvements in the

manufacture of steel."-A communication from J. Rosenthal and F. Gierow, Berlin, Prussia.-Nov. 7, 1865. 2950. A. V. Newton, Chancery Lane, "An improved

manufacture of caramel."-A communication from T. Hyatt, New York, U.S.A.-Nov. 16, 1865.

2953. S. H. Huntly, Upper Baker Street, Regent's Park, "Improvements in apparatus for obtaining fresh water from salt and impure water, also applicable for ventilating purposes."

2963. T. M. Tennant, Edinburgh and Leith, N.B., "Improvements in furnaces."

2964. W. E. Newton, Chancery Lane, "An improved process for hardening malleable and non-malleable castiron."-A communication from T. H. Jenkins, New

York, U.S.A.

5965. J. Harbert, Kidderminster, "Improvements in the production or manufacture of gas for heating or illuminating, and in the retorts and apparatus employed in such manufacture."-Nov. 17, 1865.

2998. W. Wells, Manchester, and S. Marland, Clayton, near Manchester, "Improvements in apparatus for obtain ing artificial light from volatile liquids or fluids."

3002. S. A. Bell, Epping Villas, Stratford, Essex, "An improvement in the manufacture of friction matches and tapers."

3007. J. J. Field, Upper Gifford Street, Caledonian Road, Middlesex, "Improvements in the manufacture of soap."-November 22, 1865.

NOTICES TO PROCEED.

1905. J. H. Chaudet, Rue des Emmurées, Rouen, "An improved system of manufacturing salts, sulphates, and acetates of chrome, and of applying them as mordants in dyeing and printing textile substances, both animal and vegetable."-Petition recorded July 21, 1865.

1914. J. P. Gillard, Paris, "Improvements in the manufacture of soda and carbonate of soda."-July 22, 1865. 1946. T. Pepper, Newington Green, Middlesex, "Im

to make a most uncalled-for attack on Dr. Frankland, and the illness of the other gentleman. who is represented as wilfully causing the death of one The letter caused some sensation here, and while everybody laughed at Dr. Phipson's estimate of Dr. Frankland as a chemist, of humanity he was accused of displaying. some indignation was expressed at the apparent want I need hardly say that there were a few here who knew-what I should have thought every chemist in London would have lomew's for some years, and therefore that the charges known-namely, that Dr. Frankland had left St. Barthocould not apply to him.

Dr. Frankland's own denial soon arrived, but that (probably from the fault of the French translator of the letter) seemed to deny that any such cases had happened, and caused some misconception for a moment. Dr. Odling, however, has cleared the matter up by the frank statement that the occurrences happened in his laboratory, and that no one was to blame. And now Dr. Phipson must get out of the business as he best can.

One object Dr. Phipson had in view, it seems to me, was to frighten foreign assistants from seeking engagements in London laboratories. He might as well try to is fighting to be done. Germany produces more men and frighten Germans from enlisting as soldiers wherever there chemists than are wanted at home, and they must go somewhere to live; and in my time I know foreign assistants well paid as the English, and although, as a rule, rather had nothing to complain of in London. They were as given to a spirit of detraction, they seemed in general Phipson has not increased his scientific reputation, he has I will dismiss the matter at once by stating, while Dr. acquired a reputation for something else which, I fancy, will by no means improve his standing in London.

contented.

There is really little of novelty or utility to communicate at present. M. C. Schaitner describes in Cosmos what is called a new process for extracting vegetable oils, such as those from cotton and linseed, poppy, mustard, and other seeds. The seeds are first crushed or partly pressed, and then the cakes are digested (with or without heat, as need be) in closed vessels with the lighter petroleum oils. The matters are then pressed or percolated with fresh oil, and the oily solution is submitted to distillation. The petroleum oils should be such as distil below 100° C., and therefore easily separated. I need not describe the process further. Any one will see how to carry it out if it be of any use.

That matter is not infinitely divisible is a recognised belief, yet no one has ever seen, or is likely to see, an ultimate molecule or atom. Nevertheless, M. Loschschmidt has measured one—at all events, on paper. By a process