NOTICES OF PAPERS CONTAINED IN OTHER JOURNALS. BYHENRYWATTS, B.A. F.C.S. On Osmotfe Force.* By Thomas Graham F.R.S. &c. THEexpression ‘‘Osmotic Force” (from &q-& impulsio)has reference to the endosmose and exosmose of D u t r oche t. The force of liquid diffusibility will still act if we interpose between the two liquids a porous sheet of animal membrane or of unglazed earthenware; for the pores of such a septum are occupied by water and we continue to have an uninterrupted liquid communication between the water on one side of the septum and the saline solution on the other side To impel by pressure any liquid through the pores of such a septum may be extremely difficult from the interference of frictional resistance and the attraction of capillarity.But these last forces act on masses and not on molecules and the ultimate particles of water and salt which alone diffuse appear really to permeate the channels of the porous septum with little or no impediment. A comparative experi- ment on diffusion with and without septa is easily made by means of a widemouthed phial which is filled completely with saline solution and then immersed in water in one experiment with the mouth of the phial open and in the other experiment with the mouth covered by membrane. In a fixed time such as seven days a certain quantity of salt leaves the phial by diffusion. This quantity was reduced to one-half when the strong and thick membrane of the ax-gullet was used to cover the mouth of the phial; and it was not affected in a sensible degree by passing through a thinner membrane consisting of ox-blad- der with the outer mugular coat removed.In the last experiment the actual diffusates were 0.631 grm. common salt in the absence of the membrane and 0.686 grm. common salt with the membrane interposed which may be considered as the same quantity. The diffusion of a salt appears ta take place therefare without difficulty or loss through the substance of a thin membrane although the mechanical flow of a liquid may be nearly stopped by such an obstacle It is well to bear in mind the last fact in the coosideration of what * Phil. Trans. 1854 1’77. PROFESSOR QRAHAAI ON is seen in an endosmotic experiment. An open glass tube with one end expanded into a bell form and covered by tight membrane forms a vTssel which may be filled with a saline solution and immersed in a jar of pure water.The volume of liquid in this osmometer soon begins to increase and is observed to rise in the tube while the simiiltaneous appearance of salt in the water of the jar may easily be verified. M. Dutrochet described the result as tbe movement of two unequal streams tbrough the membrane in opposite directions the smaller stream being that of the saline solution flowing outwards and the larger that of pure water flowing inwards. The double current has been always puzzling but the expression of the fact becomes more conceivable when we say (as we may do truly) that the molecules of the salt travel outwards by diffusion through the porous membrane.It is not the whole saline liquid which moves outwards but merely the molecules of salt their water of solution being passive. The inward current of water on the other hand appears to be a true sensible stream or a current carrying masses. The passage outwards of the salt is inevitable and being fully accounted for by diffusibility requires no further explanation. It is the water current which requires consideration and for which a cause must be found. This flow of water through the membrane I shall speak of as osmose and the unknown power producing it as the osmotic force. It is a force of great inten- sity capable of supporting a column of water many feet in height as shown in Dutrochet’s well-known experiments and to which naturalists are generally disposed to ascribe a wide sphere of action both in the vegetable nnd animal kingdoms.Cannot liquid diffusion itself it may first be asked contribute to produce osmose ? Diffusion is always a double phenomenon and while molecules of salt. pass in one direction through the membrane molecules of water no doubt pass by diffusion in the opposite direction at the same time and replace the saline molecules in the osmometer. Water also is probably a liquid of a high degree of diffusibility; at least it appears to diffuse four times more rapidly than alcohol and four or six times more rapidly therefore than the less diffusive salts. A possible consequence of such inequality of diffusion is that while one grain of a certain salt diffuses out of the osmometer foixr or six grains of water may diffuseinto the osmometer.Liqiiid diffusion I believe generally tends to increase the volume of liquid in the osmometer and a portion if not the whole of the small osmose of chloride of sodium sulphate of magnesia alcohol sugar and many other organic substances may be due to the relatively low diffusibility of such liquefied bodies compared with the diffusibility of water. But many substances it will immediately appear are replaced in experi- ments of endosmose not by four or six but by several hundred times their volutne of water and manifestly some other force besides diffusion is at work in the osmometer. OSMOTIC FORCE. An explanatiori of osmose has been looked for in capillarity by Poisson Magnus and by Dutrochet himself.Combining diffusion with this idea we might imagine that the pure water which first occupies the pores of the septum suffers a sudden and great loss of its capillarity-force when the salt of the osmometer enters the pores by diffusion and niixes with the water they contain. Experiments pub- lished by Dutrochet give a capillary ascension to pure water of 12 millimeters and to a solution uf common salt of density 1.12 6.14 millimeters or only one-half of the former ascension. If a porous septum occupied by such a saline solution had the same solution in contact with one surface and pure water in contact with the other surface (the actual condition of the septum in an osmotic experiment) tbe pure water should enter its pores from its high capillary attraction and like a solid piston force out the saline solution from them the saline solution so displaced would go to swell the liquid within the osmometer.When the pure water now again occupying the pores catne in time to acquire salt by diffusion the displacement would be repeated and a continuous osmose or flow of water inwards be in fact established. This explanation is attended with certain physical difficulties but it is unnecessary to discuss these as the experimental basis of the hypothesis is unsound. The great inequality of capillarity assumed anion5 aqueous fluids does not exist. Many saline solutions which give rise to the highest osmose are I find undistinguishable in capil- larity from pure water itself.To obtain constant results with saline solutions the capillary tube must be retained for some minutes in the saline solution at a boiling temperature and afterwards be cooled without removal from the liquid otherwise the indications are singu- larly irregular and most fallacious. The near equality in capillarity of solutions of the most different composition is very apparent in my observations which are placed together in the following series of capillary ascensions :-Capillary ascension of several liquids in the same glass tube. Miilimeters. Water at 58' F. . 17-75 Water at 66O . . 1755 Carbonate of potash 0.25 per cent. in water at 63' 17.2 Carbonate of potash 10 per cent. in water at 66O. 17.55 Carbonateof soda 1 per cent.at 61° . . 17-55 Carbonate of soda 10 per cent. at 55' . 16.85 Sulphate of potash 1 per cent. at 58' . 17.15 Sulphate of potash saturated solution at 58' . 16.3 Sulphate of soda 1 per cent. at 55' . . . 17.75 Sulphate of soda 10 per cent. at 58' . . 16-95 Hydrochloric acid 1 per cent. at 63' . . 17.5 PROPGSSOR GRAHAM ON Millimeters. Sulphuric acid 0-1per cent. at 63' . . 17.4 Sulphuric acid 1 per cent. at 63O. . . . 16.35 Sulphuric acid 5 per cent. at 63' . 16.65 Sulphuric acid 10 per cent. at 63' . . 16-25 Sulphuric acid undiluted (HO SO,) at 63' . 8.1 Oxalic acid 1 per cent. at 66' . . . 17.35 I Oxalic acid 4 per cent. at 62' . . 17.2 Ammonia 0.1 per cent.,.at 66' . . 16.65 Ammonia 1 per cent.at 66' . . . 16.15 Ammonia 12 per cent. (0.943 sp. gr.) at 66' . 15-05 Sugar 10 per cent. at 65' . . . 16.3 Alcohol 0.8per cent. (0.9985 sp. gr.) at SO0 . 15.5 Alcohol 495 per cent. (0.992 sp. gr.) at 63' . 13.2 Alcohol 7.8 per cent. (0-987sp. gr.) at 60" . 11-05 Alcohol 71 per cent. (0.869 sp. gr.) at 63' . . 6-Alcohol falls in the greatest degree below water in capillarity yet the former eubstance is one of the least remarkable for the power to occasion osmose. The newer facts to be related also in- FIG. 1. crease the difficulties of the capillary theory of osmose. My own experiments on osmose were made with both mineral and organic septa. 1. A convenient earthenware or baked clay osmometer is easily formed by fitting a glass tube and cover to the mouth of the porous cylinder often used as a cell in Grove's battery as in Fig.1; the cylinder was geneidly five inches in depth by 1.7 inch in width inside measure and was capable of holding about six ounces of water. Gutta percha is much preferable to brass as the material for the cap or cover. The glass tube above was also compara- tively wide being 0.6 inch or 15 milli-meters in diameter and was divided into millimeters. It was not more than 6 inches in length. Each of the divisions or degrees amounted approximatively to +th part of thecapacity of the clay cylinder. In conducting an experiment the cy- linder always previously moistened with pure water was filled with any saline solu- tion to the base of the glass tube and immediately placed in a jar of distilled OSMOTIC FORCE.water of which the level was kept adjusted to the height of theliquid in the tube of the osmometer throughout the whole experiment so as to prevent inequality of hydrostatic pressure. The volume of water in the jar was comparatively large fifty to eighty ounces. The rise or fall of the liquid in the tube was noted hourly for five hours. This rise commenced immediately and was pretty uniform in amount for each hour during the short period of the experiment. The object aimed at was to observe the osmose of the solution before its composition was materially altered by dilution and the escape of salt by diffusion. The quantity of salt diffused from the osmometer into the water-jar during the experiment was also observed.After every experi- ment the osmometer was washed out by distilled watcr which was allowed to permeate the porous walls of the cylinder under the pressure of a column of water of about 30 inches in height for eighteen hours. All the experiments were made at a temperature between 56' and 64'. The clay osmometer attained a considerable degree of uniformity in its action when the Same saline solution was diffused from it once in each of two or three successive days with a washing between each experiment. A single observation is not much to be relied upon as the first experiment often differs considerably from the others. Om per cent. solutions were always used when the propor- tion of salt is not specified.Much larger proportions of salt have hitherto been generally employed but it was early observed that the osmose absolutely greatest is obtained with small proportions of salts in solution. One part of salt to 400 water gives a higher osmose in earthenware than any other proportion for the great majority of sub-stances. Osmose appeared indeed to be peculiarly the phenomenon of dilute solutions. With the same proportion (1per cent.) of different substances the osmose varied from 0 to 80 degrees. Occasionally instead of a rise of liquid in the tube a fall was observed; the fall ntay be spoken of as negative osmose to distinguish it from the rise or positive osmose. Soluble substances of every description were tried and find a place in the following classes :-1.Suhtances of small osmotic power in porous earthenware; osmose under 20 of the millimeter degrees (tns.) This class appears to include nearly all neutral organic substances such as alcohol pyroxylk spirit sugar glucose mannite saliein amygdztlin salts of quinine and morphine tannin urea ; also certain active chemical substances which are not salts nor acids; chlorine water bromine water. The great proportion of neutral salts of the earths and metals proper also belong to the same class such as chloride of sodium of which the positive osmose was greatest in a solution containing no more than 0.125 per cent. being 19 ma. with that proportion of salt but falling off and often becoming slightly negative with 1 per cent. PROFESSOR QRAHAM ON and higher proportions of salt in solution.Chloride of potassium is similar. Nitrate of soda gave an osmose of 8 nitrate of silver of 18 ms. The salts of the magnesian oxides are all low and sometimes slightly negative. Chlorides of barium and strontium both gave IS ms.; nitrate of strontia 5 rns. ; sulphate of magnesia 0.5 per cent. 2 ms. ; 2 per cent. 3 ms. ; sulphate of zinc was very similar + 2 to -2 ms. from 0.5 to 2 per cent. ; chloride of mercury 1per cent. gave 6 and 8 ms. in two experiments. 2. Substances of an intermediate degree of osmotic force ; osmose from 20 to 35 degrees. Sulphurous acid gave 20 ms. Certain vege- table acids have a similar osmose. Tartaric acid in solutions of 0.25 1 and 4 per cent.gave 24 26 and 28 ms. ; citric acid 1 per cent. 30 ms. Also monobasic acids such as hydrochloric acid nitric acid acetic acid have the same moderate osmotic action in porous earthen- ware. -3.Substances of considerable osmotic power in porous earthenware; osmosefrom 35 to 55 ms. In this class are found the polybasic mineral acids sulphuric acid 0.5 per cent. gave even 63 ms. ; 2 per cent. 54 ms. or nearly the same osmose as the smaller proportion of acid. In another earthenware cylinder the following observations on the osmose of sulphuric acid were successively made :-Millimeters. 0.1 per cent . 43 and43 1 per cent. . 40and40 4 per cent. . 41 and 39 10 per cent. . 38and39 The results exhibit much similarity of osmose through a great range (1to 100)in the proportion of acid.So small a quantity of this acid as one part in 1000 water appears to give as great an osmose as any larger proportion of acid. Certain neutral salts sulphate of potash sulyhate of soda sulphate of ammonia belong to the same class. With sulphate of soda the osmose for the different proportions 0*125,0*25, 1 and 4per cent. of salt was 46 47 36 and 24 ms. respectively ; the osmose diminishing with the increased proportion of salt. Of sulphate of potash 0.25per cent. gave 51 ms.; 1per cent. 46 ms. and 4 per cent. 38 ms. showing no great change from one quarter to 4 per cent. ; chromate of potash 1per cent. gave an osmose of 54 nis. 4. Substances exhibiting the highest degree of osmotic power in porous earthenware.OSMOTIC FORCE. Salts of the alkalies possessing either a decided acid or alkaline reaction and certain neutral salts of potash. Binarseniate of potash gave 66 ms. ;Rochelle salt 82 ms. With binoxalate of potash the osmose observed in an earthenware osmometer was- Millimetera. For 092 per cent. . . 3.2 0.05 per cent. . . 55 0.1 per cent. . . 63 0.25 per cent. . . 70 (highestj 1 per cent. . . 63 2 per cent. . . 56 Of salts having alkaline properties phosphate of soda gave 70.5; borax carbonate of soda and bicarbonate of soda all gave numbers which ranged above 60 ms. in various osmometers. To the same class also belong certain strong acids phosphoric acid giving an osmose of 62 ms.glacial phosphoric acid of 73 ms. The caustic alkalies have probably too strong a disorganizing action upon the septum to allow osinose to proceed undisturbed. They give a positive osmose when present in a minute proportion but very soon attain their term moyen and then become slightly negative. Caustic soda 0.01 per cent. gave 24 ms. ;0.02 per cent. 29 ms. ; 0.05 per cent. 31 ms. which was the highest osmose observed; 0.1 per c_ent. 22 ms. ; 0.25 per cent. 3 ms. ; 1per cent. and 2 per cent. of caustic soda gave both -10 ms. It appears most clearly that highly osmotic substances are also chemically active substances. Both acids and alkaline substances possess the affinities which would enable them to act upon the silicates of lime and alumina which form the basis of the earthenware septum.Lime and alumina were aecordingly found in solution after osmose and the corrosion of the septum appeared to be a necessary condition of the flow. It was found impossible to exhaust the whole soluble matter of the walls of the earthenware osmometer by washing either with water or with a dilute acid for the process of decomposition appeared to be interminable. After such washings the action of an osmometer was often greatly modified upon salts of moderate osmose such as chloride or sodium ; and similar changes gradually took place in the osmometers when used in ordinary experiments with saline solutions. It is on this account that I avoid the lengthened detail of numerous experiments which were made with the earthenware osmometer and confine myself to general statements.Further the potash salts were also largely kept back or absorbed by the earthenware a pheuomcnon of the same class as the retention VOL. VII1.-NO. XXIX. E PROFESSOR GRAHAM ON of alkalies by aluminous soils which has been studied by Mcssrs. Thoinson and Way. Other septa which were not acted upon by the salts were found deficient in osmotic activity although possessed of the requisite degree of porosity. Gypsum compressed charcoal and tanned sole- leather gave rise to no osmose when permeated by saline solutions. White plastic clay had an osmotic power which was quite insig- nificant when conipared with that of baked clay now the former may be considered as an aluminous compound upon which the de- composing action of water has been already exhausted while the latter is in a form more liable to decomposition in consequence of an effect of heat upon the constitution of the aluminous silicates of the clay.A plate of Caen stone which is an impure limestone was greatly more active with a solution of carbonate of potash than apiate of pure white marble was. The effect of impurities in making lime- stone suitable for osmose did not escape the observation of D utrochet ; it was referred by him to the attraction of alumina for water. Mere capillarity therefore is insufficient to produce the liquid move- ment while the vis motrix appears to be some form of chemical action. For the proper appreciation of a chemical theory of the osmotic force I would now invite attention to a purely speculative subject namely the molecular constitution of water and saline solutions.Allowing that water in the state of vapour is corrcctly represented as a compotind of one equivalent of oxygen and one of hydrogen it may still be true that the molecule of Ziqztidwuter is a varying aggregate of many such molecules or is n times HO. But if so much is conceded a new and peculiar grouping of the atoms of oxygen and hydrogen becomes not only possible but probable. Instead of arranging them in a series of pairs of H +0 H +0 in our compound molecule we may give a binary form to that molecule in which a single atom of oxygen is the negative or chlorous member and the whole other atoms united together form a positive or basylous radical.In thismdical we have a certain multiple of HO with ortc H in excess the last condition being most usual in compound radicals such as ethyl methyl benzoyl &c. which have all a single unbalanced equivalent of hydrogen ; H,O,= (k!m+lOm)+0. Further this new oxide should be more easily decomposed than oxide of hydrogen HO. The basicity of the radical (Hm+ depends upon the disproportion of the equivalents of oxygen and hydrogen in its constitution there being one of hydrogen in ~XCCYS. Now that disproportion becomes less as we ascend as in 3H+20 11H +100 1OlH+1000; and the more feeble the basyl-atom it may be supposed to retain less forcibly its fellow oxygen-atom or other negative element with which it iscombined.When water therefore has to undergo decomposition in a voltaic circle it will naturally assunie the molecular OSMOTIC FORCE. wrangement supposed as being the binary form which is most easily divisible into a positive and negative element or that in which water is most easily decomposed. This molecular view has been brought forward at present principally for the aid which it gives in conceiving what is known as electrical endosmose. This interesting phenomenon first well developed by our colleague Mr. Porrett has very lately been defined with great clearness by M. Wiedemann.* The water which accumulates at the negative pole (or follows the hydrogen) in the electrolysis of the pure liquid is found to be exactly proportional to the amount of circulating affinity ; that is with every equivalent of hydrogen that is discharged at the negative pole the same quantity of water arrives there and will force its way through a porous diaphragm to reach that destination.The reason now suggested is that the travelling basylous atom in the voltaic decomposition IS not hydrogen simply but the voluminous basylous molecule (H,+lOm) above described; which again breaks up at the negative pole into hydrogen and water (Hm+lOm) =mHO and H. But even although such a representation of the circumstances of electrical endosmose may not be fully admi'tted the phenomenon itself is of great service to us as showing that in the occurrence of chemical decompositions affecting ultimate particles sensible volumes of water may be involved and set in motion.Further in considering the action of chemical affinity between bodies in solution between an acid and alkali for instance we are apt to confine our attention to the principal dctors in the combination and to neglect entirely their associated water of hydration. Yet both the acid and base may have large trains of water attached to them by the tie of chemical union. Sulphuric acid certainly evolves heat with the fiftieth equivalent of water that is added to it and probably in dilute solution that acid is capable of having a still greater number indeed an indefinitely large number of equivalents of water conibined with it. In fine there is reason to believe that chemical affinity passes in its lowest degrees into the attraction of aggregation.The occurrence of chemical deconiposition within the substance of a porous resisting septum may be calculated to bring into view the movement and disposal of the water chemically associated in large quantities with the combining substances ; as the interposition of a porous diaphragm in electrical endosmose makes sensible a translation of water in voltaic decompositions which is not otherwise observable. 11. The osmose of liquids has hitherto been principally studied in septa of an.imnZ membrane which from their thinness their ready permeability combined with a sufficient power of resistance to the f Pogg. Ann. lxxsvii. 321. PROFESSOR GRAHAM ON passage of liquids under pressure have great advantages over mineral subst an ces.The great proportion of the experiments of the present inquiry were also made with animal membrane. The membrane osmometer employed which is only a modification of the classical instrument of Dutrochet was prepared as follows :-The mouth of a little glass bell-jar A (fig.2) had first loosely applied to it a plate ofperforated zinc B slightly convex and then the membrane was tied tightly over the latter for the sake of support (fig. 3). The FIG.2. FIG.3. B quantity of metal removed in the perforations of the zinc plate amounted to 49 per cent. of the weight of the zinc. This plate was always varnished or painted to impede if not entirely prevent the solution of the metal by acid fluids.The usual diameter of the bulb was about 3 inches or 75 millimeters and its capacity equal to 5 or 6 oz. of water. The tube C was usually not more than 6 inches in length but comparatively wide its diameter being about 7-5 millimeters that is one-tenth of the diameter of the mouth of the bulb and it was divided into millimeters. The action of an osniomcter depends chiefly upon the extent of membrane-surface exposed and very little upon the capacity of the instrument. Hence the relation of diameters (or areas) between the bulb and tube was adopted in preference to the relation in capacity the area of the section of a tube being one-hundredth of the area of the disc of membrane or rather it was reduced by calcu-lation to this relation by means of a coefficient for each instrument.OSMOTIC FORCE. Hence a rise of liquid in the tube amounting to 1.00 millimeters indicates the adrnission into the bulb of a sheet of water of 1 millimeter (one twenty-fifth part of an inch) in depth over the whole surface of the membrane and so in proportion for aoy otber rise in the tube. These millimeter divisions {ms.) of the tube mark therefore deqrees of mmose which have an absolute and equal value in all instruments. The bulb of the instrument filled with the solution to be operated upon was placed within a cylindrical glass jar of distilled water con- taining at least sixty ounces (fig. 4) and during the experiment inequality of hydrostatic pressure was carefully avoided by maintain- ing the surface of the water in the jar at the level of the liquid in the tube.The osnionieterwas supported upon a tripod of perforated and painted zinc at a height of about 4 inches from the bottom of the glass cylinder. The osmose was observed hourly for five hours during which time it advanced in general with coiisiderable uniformity. In an experiment with fresh ox-bladder as the septum and a solution of 1 per cent. of carbonate of potash in the osmometer the rise in five consecutive hours was 10 12 11 14 1.3 millirneter degrees and in five hours iniinediately following 13 12 9 11 and 12 niilIimcter degrees making sixty degrees in the first and fifty-seven degrees in the second period of five hours. The quantity of salt which diffused outwards during the experiment of five hours was also frcquently determined usually by evaporating the liquid of the water-jar to dry- ness; it rarely exceeded one-tenth part of the salt originally present in the osmometer.The membrane itself was also weighed before it was applied to the osmometer and again when its use was discontinued which was generally after six or eight experiments had been made with the membrane. A loss of the substance of the membrane was always observed varying from 20 to upwards of 40 per cent. of its original weight. The outer miiscular coat of bladder soon becomes putrescent and from changes in its consistence and the large quantity of salts and YROPESSOR GRAHAM ON other soluble substances which it yields by decomposition gives occa- sion to much irregularity in the experiments.The great change in the amount of osmose often produced by merely turning the memhrane observed by M. Mat teucci and others depends often I believe upon the soluble matter of the muscular coat being thrown outwards or inwards according as the membrane is applied. The muscular coat was on this account removed from the ox-bladder employed and the serous membrane remaining found to acquire greatly increased activity and also to act with much greater regularity in successive experiments. The membrane so prepared could be used for weeks together without the slightest putrescence of any part of it. Two of these thin mem-branes or a double membrane were often applied. The weight of a disc of single membrane 44 inches in diameter in a dry state varied from about 0.5 to 1.2 gramme.The soundness of the membrane of an osmometer and its degree of permeability were always roughly tested Before an experiment by filling the bulb without its tube completely with water hanging it up in air and observing how frequently a drol) fell from the instrument. The time between each drop' varied with suitable membranes from one to twenty minutes. The times in which water permeated the same membranes by osmose varied between much narrower limits perhaps from one to two. The quantity of salt which traversed different membranes by diffusion was also found to be in proportion to the osmotic permeability of the membranes and not to their nicchanical porosity.To wash the membranes they were maceiated in distilled water after every experiment for not less than eighteen hours without being ever removed from the glass bulb. A membrane also was never allowed to dry but was kept humid as long as it was in use for experiments. Osinose in membrane presented many points of similarity to osrnose in earthenware. The membrane was constantly undergoing decom- position soluble organic matter being found both in the fluid of the osmometer and in the water of the outer jar after every experiment ; and the action of the membrane appeared to be exhaustible although in a very slow and gradual manner. Those salts and other substances of which a small proportion is sufficient to determine alarge osmow are further all of the class of chemically active substances while the great mass of neutral organic substances and perfectly neutral monobasic salts of the metals such as the alkaline chlorides possess only a low degree of action.When a solution of the proper kindris used in the osmometer the passage of fluid proceeds with a velocity wholly unprecedented in such experiments. Take for instance the rise in five hours exhibited in a series of experiments upon solutions of several different proportions of carbonate of potash made in succession with the same membrane in the order in which they are related. OSBfOTIC FORCE. 55 Millirnet eps. With 0.1 per cent. carbonate of potash a rise of 182 With 0.1 per cent. carbonate of potash a rise of 120 With 0.1 per cent.carbonate of potash a rise of 199 With 0.5 per cent. carbonate of potash a iise of 246 With 0.5 per cent. carbonate of potash a rise of 194 With 1 per cent. carbonate of potash a rise of 205 With 1 per cent. carbonate of potash a rise of 207 Or the rise in the same tinie with another membrane which had been pqeviously exposed to a steam heat of 212' for ten minutes without impairing its activity. Milliinetew. With 1 per cent. carbonate of potash at 60' F. a rise of 402 With 0.1 per cent. carbonate of potash at 60' F. a rise of 196 With 0.1 per cent. carbonate of potash at 60' F. a rise of 153 With 2 per cent. carbonate of potash at 60' F. a rise of 511 With 4 per cent. carbonate of potash at 60" F. a rise of 781 With 10 per cent.carbonate of potash at 60' F.,a rise of 863 In thc last experiment a rise of fluid in the tube of upwards of 30 inches occurs in five hours and so much water is impelled through the membrane as would cover its whole surface to a depth of 8.6 millimeters or one-third of an inch. Both membranes bat particularly the first show the comparatively great activity of small propoldions of salt the average osmose of 0.1 per cent. of carbonate of potash in the first osmometer being 167 millimeter degrees and of 1 per cent. 206 millimeter cleyrees. Now the quantity of carbonate of polash which diffuses out of the osmometer into the water-jar was determined by the alkalimetrical method in the second and third of the 0.1 per cent. observations first related and found to be in both cases 0.018 gratnme (0-28 grain) ; the quantity of water also which entered in return can be calculated from the known capacity of the tube of the osnioinetw of which each niillimeter division represented 0.060 gr:imnie of water ; and conseqaen tly 167 divisions represent 10.020gramrnes (155 grains) of water.We have in 0.1 per cent. solution,- Mcan diffusate of carbonate of potash . 0.018 grm. = 1 Mean osmose (of water) . 10.020 grms.=556 The conelusion is that while the membrane was traversed during the five hours of an experiment by 1 part of carbonate of potash passing outwards it was traversed by 556 parts of water passing inwards. In the two experiments with 1 per cent. solution of carbonate of potash in the same osmometer the diffusates were 0.192 and 0.198 gramme of carbonate of potash which are sensibly ten times greater than the diffusates of the 0.1per cent.solution. But the mean osmose PROFESSOR GRABA lf ON of the 1 per cent. solutions is greater than that of the 0.1 per cent. solutions only in the proportion of 206 to 167 or as 1to 0.81. The ratio in question however varies greatly in different membranes. We have consequently in 1 per cent. solution,- Mean diffusate of carbonaie of potash . 0.195 grm. = 1 Mean osmose (of water) . . 13.360 grms. =63.4 Whatever therefore be the nature of the chemical action occurring in the membrane which influences osmose a minute amount of that action appears to be capable of producing a great mechanical effect.All idea of contractility or organic structure being the foundation of the osmotic action of membrane was excluded by the observation that similar large effects could be obtained from a septum of pure coagulated albumen. A convenient albumen osmometer is constructed by covering the opening of the bulb of the former instrument by ordinary thin cotton calico which is best applied wet and painting over the outer surface of the calico two or three times with undiluted egg albumen an hour being allowed to elapse between each application of the albumen. The instrutnent is then suspended in the steam rising from boiling water for a few minutes so as to completely coagulate the albumen. The albnniinated calico may then be macerated for twenty-four hours before use by placing the osmometer in cold water to dissolve out the soluble salts of the albumen.It should be preserved always in a humid state. Before application to the calico the albumen in many cases was neutralised with acetic acid and filtered the more completely to obliterate every trace of organic structure. The osniose in a particular instrunient of this kind was at 50° for Millimeters. 1 per cent. carbonate of potash 1 per cent. carbonate of potash1 per cent. carbonate of potash 0.1 per cent. carbonate of potash0.1per cent. carbonate of potash . . . . . . 211 . 367 . 387 . 127 . 124 The correct rate is rarely obtained in the first observation as seen above in osmometers of albumen as well as of other materials.The albumen plate has generally a greater thickness than prepared membrane which appears to diminish proportionally the quantity of salt which escapes by diffusion. The diffusate in the three experiments above of 1 per cent. carbonate of potash was 0.024 0.038 and 0.042 grm. of the salt. The largest proportion of carbonate of potash (0.042grm.) which was OSMOTIC FORCE. obtained in the last of the three experiments was replaced by 23.220 grms. of water or 552 times the weight of the salt. An obvious and essential condition of osmose is difference of com-position in the two fluids in contact with the opposite sides of the porous septum. With the same solution or with pure water in con- tact with both surfaces of a membrane there may be no chemical action but it will be equal on both sides and although probably attended with movements of the fluids pet nothing will be indicated as the movements being equal and in opposite directions must neu- tralise each other.Difference of composition in the two fluids is necessary in order that there may be inequality of action upon the two sides of the membrane. It is difficult however with respect to the chemical action to ascertain either its true sphere or its exact nature. No substance appears to be permanently deposited in the membrane during osrnose even by easily decomposed metallic salts such as salts of lead and niercury. The action upon the membrane is probably of a solvent nature and its seat may possibly be ascertain- able when two membranes are used together.Some observations made on the comparative loss of weight of the outer and her mem- brane have not however shown any remarkable difference. But this again may arise from the great proportion of the loss in both mem- branes being due to the ordinary solvent action of water alone and the operative solvent action of the osmotic salt being comparatively minute in amount; or it may depend and I ilin most inclined at present to take this view upon the chemical actions being of a different kind on the two sides of the membrane and not upon the inequality simply of one kind of action. Such a supposition was suggested by the fact which will immediately appear that osmotic activity and easy decomposition are properties often found together in binary compounds.The basic and acid agents then developed are both capable of acting upon albuminous septa. We may imagine for instance in the osmo-tic action of a neutral salt the formation within the thickness of the septum of a polar circle one segment of which (composed of the bi- nary molecules of the salt) presents a basic molecule to the albumen at the inner surface of the septum and an acid molecule to the albu-men at the outer surface the circle being completed through the substance of the septum which forms the second segment. Both surfaces of the septum would be acted iipoii but at one side we should have combination of the albumen with an alkali on the other side with an acid. This however must be taken as a purely ideal representation of the condition of the scpturn in osmose.I have not discovered such a polar condition of the septum and I doubt whe- ther the galvanometer could be properly applied to exhibit it as the placing of the poles of that instrument in the dissimilar fluids exist- ing on opposite sides of the septum would alone be sufficient to give 58 PROFESSOR GRAHAM ON rise to voltaic polarisation. At present 1 must confine myself to the enunciation of certain general empirical conclusions respecting the operation of chemical affinity in osmotic experiments. With animal septa frequent examples of the outward flow of liquid from the osrnometer present themselves causing the liquid column to fall instead of rise in the tube. This phenomenon (exos- mose) I have spoken of as negative osmose.The observation of Dutrochet that oxalic acid in the osrnometer and also tartaric acid at a certain point of concentration give rise to negative osmose I have been able to generalise in so far as acids have universally either a nc,gative osmose or lie at the very bottom of the positive class. Oxidic acid gave in membrane for 1 per cent. acid -1448 nis. and -14lms. ;and for 0.1 per cent. -10 and -27ms. In another membrane 1per cent. of the same acid alone gave -136 ms. ; with the addition of 0.1 per cent. hydrochloric acid -181 and -168 ms. By the addition of 0.1 per cent. of chloride of sodium a salt which in small proportions is nearly neutral to osmose the negative ostnose of 1 per cent.oxalic acid fell in the same membrane to -45 ms. and with the addition of 0.25 per cent. of chloride of sodium the osmose was +6 ms. or became slightly positive. The negative osmose of 1 per cent of oxalic acid in a membrane where it amounted to -56 and -57 ms. in two experiments became with the addition of 0.1 per cent. of albumen -46 ms. ; of 0.25 per cent. of albumen -20 ms.; of 0.25 per cent. of gelatin -59 ms. and of 0.25 per cent. of sugar -53 ms. In albuminated calico the osniose of 1 per cent. of oxalic acid was also negative namely -19 -16 and -20 ms. in three successive observations. With the addition to the oxalic acid of 0.1 per cent. hydrochloric acid the osmose became -46 and -58 ms. ;and with the addition of 0.1 per cent. of sulphurous acid the osmose becanie -62 and -58 ms.Of hydrochloric acid introduced into the membrane-osmometer in the small proportion of 0.1 per cent. the negative osmose was -92 -37 and -27 ins. in three successive experiments. The negative osmose of hydrochloric acid was still more powerfully counteracted than that of oxalic acid by the association of a minute proportion of chloride of sodium with the acid. The negative osmose of this acid appears to be extremely precarious. It is reversed by a great variety of neutral soluble substances and on that account can rarely be ob- served at all with bladder undivested of its muscular coat. In a certain prepared membrane sulphuric acid 0.1 per cent. gave an osmose of -4 +8 and +7 ms. Nitric acid 0.1 per cent.gave an osmose at 58O of +8 and +23 ms. OSMOTIC FORCE. 59 Tribasic phosphoric acid 1per cent. gave -6 and -7 ms. at 61' and 63'. The diffusates of phosphoric acid in the same experiments amounted to 0.143 and 0.130 grm. The glacial or monobasic phosphoric acid 1per cent ,gave +137 and +131 my. at 55O which is a considerable positive osmose an interesting circutnstance when taken in connexion with the deficient acid character of that modification of phosphoric acid. The same acid 0.1 per cent. gave a positive osmose in the last memhrane of 28 and 23 ms. Citric acid 1per cent. gave 39 and 36 ms. ; 31 and 31 ms. at 63'; the first in membrane and the second in albumen. The same acid 1per cent. after being fused by heat gave at 63' -38 and -33 nis.in membrane ; 0 m. and -2 nis. in albumen. A small proportion of fused citric acid 0.1 per cent. gave on the other hand a slight positive osmose namely 15 ms. and 2 ms. in the previous membrane and albumen osmonieters respectively. Tartaric acid 1per cent. give 18 and 19 ms. in membrane at 68' ; with 20 ms. in albumen at 62'. The same acid after being fused by heat gave -68 and -61 ms. in membrane at 57' showing a molecular change from fusion as in citric acid. The diffusate in the last two experiments was 0.123 grm. and 0.132 grm. of acid. In albumen the osmose of fused tartaric acid remained slightly posi-tive being 5 and 2 ms. for 1 per cent. at 60° and 5 and 3 ms. for 0.1 per cent. at the same temperature. Racernic acid 1per cent.gave 4 11 and 7 ms. in three experi- ments at 55O in the last-used membrane ;with 15 and 22 ins. at the same temperature in albumen ;or was always slightly positive like tartaric acid. Aceticacid in the proportions of 0.1 0.5 and 1per cent. gave scnsibly the same small positive osmose 25 to 28 ms. at 57' to 62' in membrane. A saturated solution of carbonic acid in water gave 25 and 26 ms. in membrane with 20 and 22 ms. in albumen both at 65'. The last solution diluted with an equal bulk of water gave an os-mose of 15 and 11 ms. in meuibrane and 16 ma. twice in albumen both at 63'. Terchloride qf gold is negative in its osmose like the stronger acids giving -49 and -54 ms. in membrane at 66' with much reduction of metallic gold in the substance of the membrane.BichZoride of platinum made as neutral as possible by evaporation gave for the 1per cent. solution -32 and -30 ms. in membrane at 61'. For the 0.1 per cent. solution a positive osrnose of 27 14 and 5 ms. in three successive experiments made with the last membrane 60 PROFESSOR GRAHA3f ON at 64' 65' and 62'. The same 1 per cent. solution gave in albumen at Sl" a positive osmose of 54 and 50 ms.; the0.1 per cent. solution also at 64' gave 4:3 ms. Albumen appears thus to be less adapted for bringing out the negative osmose of various substances than mem- brane is. In membrane bichloride of tin 0.1 per cent. gave 24 ms. at 61' 1per cent. -46 and -71 Ins. at 59'. The addition to the last of 0.5 per cent. of sulphiiric acid gave -63 ms.or did not alter the character of the osmose. But partial neutralisation of the 1per cent. tin solution by ammonia on the other hand gave 0 m. or destroyed all osmose. One per cent. of bichloride of tin gave only a small negative osmose in albumen namely 5 ms. twice at 59'. Oxalic acid carries the highly negative character of its osmose into the hinoxalute v'potash of which 1per cent. of anhydrous salt gave in membrane -112 and -99 ms. at 6%'; 0.1 per cent. -30 ms. at 60". One per cent. of the same salt in albuminated calico gave -20 ms. at 60". A saturated solution of binoxalate of potash con- taining 2.5 per ceut. of salt gave -15 MS. in the last osmometer. Bisulphate of potash 1per cent. gave 4 and 7 ms. in membrane at 96'; in albumen 7 3 and 6 ms.at 56'. A solution of bitartrate of potash saturated in the cold also gave a small positive osmose namely 4 and 2 ms. in membrane and 20 and 17 ms. in albumen both at 56'. Other supersalts tried gave also a srnall positive osniose such RS binarseniate of potash and bi- chromate of potash. It becomes doubtful therefore whether any of the supersalts of potash are negative except the acid oxalates of that base. Neutral organic sitbstances dissolved in water appear to be generally deficient in the power to give rise in membrane to that osrnose which depends upon a small quantity of the soluble substance such as 1per cent. or a still less proportion. The osmose obtained in ox-Gladder employed without removing the muscular coat was in 1per cent.solutions of the substances salicin 5 ms. tannin 3 ms. urea 4 ms. gelatin 9 ms. amygdalin 6 ms. lactine 7 ms. gum-arabic 18 ms. and hydrochlorate of morphine 4 ms. The relations to osinose of alcohol and sugar were more fully ex-amined. With these and other chemically inactive substances the osmose although small for 1per cent. increases progressively with larger proportions of the substance and also bears a close relation to the proportion of substance diffused outwards circumstances which give a mechanical character to the ostnose. It is with such suh-stances that the influence of diffusibility iipon osmose is most likely to betray itself. They have a peculiar interest in the study of the phenomenon as they present a certain small but remarkably uniform OSMOTIC FORCE.amount of osinose without the known intervention of any strong chemical affinities. Alcohol.-In describing an experiment I shall endeavour to put forward all the circumstances which can be supposed to influence in any way the result. In the table which follows Column I. contains the proportion of absolute alcohol by weight which is dissolved in the water of the osmometer. A 10 per cent. solution is prepared by weighing 10 gramrnes of the substance and then adding water to it so as to make up the liquid to the volume of 100 grammes of water. It is necessafy to make up in this way solutions used in experiments of diffusion and osniosc in order to preserve a true relation in solutions containing the difl'erent proportions of substance for it is a fixed volume (not weight) of these solutions which must be used in the osmometer.We come thus to have with a 20 per cent. solution of alcohol exactly twice as much alcohol in the osmometer as with a 20 per cent. solu- tion of alcohol and so of other proportions. The membrane of the osmorneter is always to be considered as fresh or as used for the first time in the first experiment narrated and the observations to be made siiccessively as they stand in the table. The length of maceration in cold water to which the membrane has been exposed previous to the osmotic experiment as before de- scribed is given in Column V. By the most frequent time of one day is to be understood the space of eighteen hours which intervened between experiments on successive days.The hydrostatic resistance of the membrane given in Column VT. is the length of time in minutes observed to elapse between the fall of two drops from the bulb of the osmometer filled with distilled water and hung up in air as already described. The temperature of the water in the glass cylinder during the experiment is noted in Column VII. ;the rise of fluid in the tube of the osmometer or osmose in millimeter divisions of the tube appears in Column .TI.,and the absolute amount of the same osmose is expressed in Column 111.in granimes or more strictly in gramme measures of water Lastly the weight of diffusate found in the water of the glass cylinder appears in Column IV.These last two data the osmose and diffusate both in grammes afford the means of comparing the weight of substance which has escaped from the osmometer with the weight of water which has entered the osmometer in the same time. It is necessary however to recollect that the apparent osniose or rise observed is only the excess in volume of the liquid which has entered over the volunie of the liquid which has left the osmometer. To obtain the full volume of water which has entered (the true osmose) it is therefore neces- sary to add the bulk of the substance diffused to the osmose observed. PltOPESSOR GRAHAM ON TABLE1.-Alcohol in Osmometer A of double membrane during five hours. I. 11. 111. IV. v. VI. V1I. ~ Alcohol in solution. Rise or osmose in millimeter degrees.Rise or oRmose in pmmes of water. Dif€~sat e Of alcohol in grammes. Previous maceration Of membrane. Iydrosta tic resistance Of niembrane. Cempera-t ure Fahr. per cent. 025 12 - - days.1s min. S 0 63 c.25 7 - - 1 8 63 1 1 10 15 - - 3. 1 6 8 66 66 2 2 20 22 - - 2 1 6 6 67 69 5 45 1.984 0.522 2 6 72 5 45 I .98d 0.452 1 8 70 10 70 3.072 - 1 8 67 10 76 3.328 - 1 8 67 20 2 0 107 109 4.672 4-800 - 1 1 8 8 (i7 67 A second series of observations was made simultaneously in another membrane osmometer in order to ascertain the degree of concordance to be expected in such experiments. TABLE11.-Alcohol in Osmometer B of double membrane for five hours. 11. I. -111. IV. v. QI. VII. -~ _.-Rise or Rise or Diffiisate Previous -Eydrostatic Alcohol osmose in osmo3e in Of maceration resistance Tempera-in millimeter ;rammes of alcohol in of of ture solution.dcgrees. water. grammes. membrane. nembrane. Ftthr. ---.__-0 per cent. day8. min. 1 14 I 2g 22 63 1 14 -1 12 03 2 19 -1 8 00 2 19 I 1. 8 60 5 46 -1 8 67 5 54 2.432 1 8 69 10 90 4.028 2 6 72 10 96 4.332 1 8 70 20 120 5.396 1 8 67 20 123 5.472 1 4 67 20 137 6.156 1 4 67 20 142 6-384 I 4 G7 It will be observed that the osmose increases with the proportion of alcohol but not in so rapid a ratio ; the osruosc of thc 20 per cent. OSMOTIC FORCE. 63 solution being about oiily ten times greater than that of the 1 per cent. solution in both series. The hydrostatic resistance of the mem-brane B falls off in a remarkable manner in the later experiments indicating an increased facility of permeation which may influence the increased osrnose in the last two observations of this series.The results otherwise of the two series exhibit a fair amount of correspon-a dence both in the degree of osmose and the amount of diffusate for the same proportions of alcohol in the two osmometers. It should he added that in several instances the water in the jars was changed after the third hour of the experiment with the higher proportions of 10 and 20 per cent. The alcohol was determined after it had been concentrated by two distillations by means of Drinkwater's table of densities. Several experiments were made to determine the proportion of the diffusate of alcohol from 5 and 20 per cent.solutions respectively of that substance in membrane osmometers. The mean proportion was as 1 to 3.02,which is mentioned here as I was led at first to a different conclusion by earlier and imperfect experiments. Sugar.-The osniose of sugar in membrane was examined very fully in the hope that the simple effect of diffusion would be exhibited without being modified by any chemical action in a substance so ent ire1 y neutral. Crystallised canc-sugar wad made use of. TABLE 111.-Sugar in Osmonieter D of double membrane for five hours. I. 11. 111. IT. V. VI. VII. Sugar Rise in Same in Diffusate of kmpera-in millimeter grammes of sugar in Previous lydrostatic ture solution. degrees. water.grammee. maceration. resistance. Fahr. 0 per cent. days. min. 1 21 1.027 -1 4 64 1 8 0-395 0.150 0 24 83 1 19 0'948 0.140 1 3+ ti3 2 19 0.048 0.178 1 23 66 > 19 0.048 0.1 82 1 24 66 u A 30 1.900 0.438 1 2+ 67 5 49 2.370 0.480 1 2$ 60 10 66 3.239 1.1 10 2 2$ 72 10 79 3-871 0.853 1 23 70 10 76 8-713 0.840 1 3 67 20 121 5'976 1.376 1 3 07 20 117 6.688 1'485 1 3 67 It was very desirable to find whether the deviations from a re-gulay progression seen in the numbers for the osmose and diffusate in PROFESSOR GRAHAM ON the preceding results are essential or accidental and peculiar to the present membrane. It was also desirable to find whether a membrane would stand the repetition of such a series of experiments and continue to give similar results.A double series of experinients were accord- ingly made with new membrane. TABLE 1V.-Sugar in Osmometer E of double membrane for five hours. I. 11. 111. IV. V. TI. VII. -__I ~ Sugarin solution. Rise in millimeter degrees. Same in Zrammes of water. Diffusate of sugar in -grammes.-Previous maceration. lydrostaticresistance. 'empera. ture Fahr. per cent. 0.25 3 0.240 - day8. 2 min. 10 0 63 0.25 9 0.420 0.050 1 10 63 1 12 0-531 0.110 1 8 G6 1 11 0.472 0. LOG 1 10 6fS 2 24 1-OGO 0,205 1 8 67 2 31 1-357 0.608 1 8 69 6 65 2.89 1 0.600 2 8 72 5 ti3 2.773 0-555 1 8 70 10 69 3.933 1.073 1 10 87 10 10 104 !I B 4.602 4'248 0.967 - 1 1 10 10 67 67 20 133 5.900 1.457 1 10 67 20 106 4.720 2.643 10 10 64 20 118 5.25 1 I656 1 6 ti4 1 19 0.828 1.105 1 6 08 1' 19 0-826 - 1 6 (i5 2 24 1062 0.153 1.6 85 2 25 1.121 0.162 1 6 64 6 37 1.652 0.435 2 8 G8 r> 33 1.425 0.470 1 8 67 10 89 3.068 0.757 2 8 67 10 76 3-368 - 1 8 69 20 110 4.H07 - 1 8 70 20 112 4.956 1.540 2 3 70 The diffusates of sugar (Column IV.) were obtained by evaporating the fluid of the water-jar to dryness at 212O and therefore contain organic matter dissolved out of the membrane ; the weight of each of the diffusates is increased by this addition a few thousandths but not in such a quantity as to affect the result to an extent that is at all material except in the first diffusate recorded that from the 0.25 per cent. solution. Although the results exhibit several irregularities yet starting from the 1 per cent.observation in the first series of Table IV. the amount both of osmose and diffiisate appears compatible with an arithmetical progression in the observations from 1 to 10 per cent. Thus the average rise in thc 1 per cent. solution is 11.5 millimeter OSMOTIC FORCE. degrees and in the 10 per cent. solution 96.3 ms.; the average diffusate in the 1per cent. solution is 0.108 gramme and in the 10 per cent. solution 1,020gramme. But with the 20 per cent. solution both osmose and diffusate fall off greatly and the osmose more than the diffusate. The osmose of the 20 per cent. solution may be taken as 125 ms.,-the mean of the first and third Observations 133 and 118 the intermediate ob- servation 106being obviously exceptional possibly from the unusually long maceration of the membrane immediately preceding that experi- ment.Hence the osmose only rises froin 96.3 ms. to 125 ms. while the proportion of sugar in the osrnometer was increased from 10to 20 per cent. The mean diffusate of sugar also increases with the same change only from 1.020 gramme to 1.585 graninie. In the second series of observations with the same membrane given in the lower part of the same Table both the osmose and diffusate fall off to an extent which is perhaps pretty fairly repre- sented by the 10 per cent. solution which gives a mean osmose of 72.5 ms. against 96.3 nis. in the former series and a diffusate of 0.757 gramme against 1.020 gramme in the former series.A rough proportioiiality between the two series of observations is sufficiently indicated. Two observations are recorded in the last series which must not be allowed to mislead. These are the coinpariltively high osmose of 19 ms. for the 1 per cent. solution which is accidental and arises from the 1per cent. experirncnts having beeu immediately preceded by the high propoition of 20 per cent. The other observation referred to is the high diffusate of the last 20 per cent. solution at the bottom of the table which has no doubt been occasioned by the sudden dimi- nution in the hydrostatic resistance of the membrane from 8 to 3 in that which is the last experiment of the series. Tie membrane indeed appears to be giving way after its long use for the osmometer had been exposed to the action of water for thirty-five days without inter- mission.The reason why the diffusion and osrnose are smaller in the second series of experiments than in the first series (nearly as 3 to 4),is (I believe) that the membrane softens and swells somewhat by the pro- tracted action of water ;a change in the structure of the membrarie which impedes diffusion by increasing the length of the channels through which the salt has to travel. It may now be interesting to discover the proportion between the water which enters and the sugar which leaves the osmometer in these experiments. That proportion appears not to vary greatly in the range froin the 1 to the 10 per cent. solution. For a mean result the sum of the eight cliffmates between 1 and 10 per cent.inclusive in the first series of observations of Table IV. may be taken VOL. vIIr.-RTo. XXIX. F PROFESSOR GRAHAM ON I. 11. 111. -VI. VII. V. . Sugar Rise in Same in Diffusate of' Tempera-in millimeter grammes of sugar in Previous Hydrostatic ture solution. degrees. water. grammes. maceration. resistance. Fahr. I ---IT. 0 per cent. day. min. 1 16 0.684 0'124 1 2 59 1 22 0.912 0-156 1 10 60 4 31 1'31 1 0.476 1 1 61 4 42 1.767 0-505 1 1 63 4 34 1.423 0 542 1 1 63 10 92 3.876 1.285 1 0.50 63 10 106 4 369 1.179 I 0.66 64 i 10 90 3'762 1.193 1 1 63 OSMOTIC FORCE. This osmometer is remarkable for the variable but generally very small amount of its hydrostatic resistance a condition of the septum which is apt to increase the diffusate owing to the expulsion of a portion of the solution by the pressure of the dense solution.The diffusates of sugar (Column IV.) may be considered as nearly pro- portional to the per-centage of sugar in the osmometer. The osmose of the 4 and 10 per cent. solutions are also nearly proportional the means being 36 and 96 ms.; but the osmose of the 1per cent. solu-tion is sensibly in excess. A slight excess it1 the early experiments with an albumen osrnometer is it may be remarked not unusual and appears to be due to the considerablequantity of soluble matter with an alkaline reaction which the fresh albumen affords to the water in the osmometer this soluble matter then acting as an osmotic body.SuZphate of Magnesia.-This salt was selected to illustrate the os-mose of neutral salts. The sulphate of magnesia is neutral to test- p!per. It.appears further to be incapable of passing into the con- dition of a stable supersulphate or subsulphate by combining with an excess of either acid or base and is not decomposed in diffusion. Such properties secure to a salt aremarkable indifference,orabsence of chemical activity and recommend sulphate of magnesia for our present purpose. In a fresh double membrane 1per cent. of sulphate of magnesia (anhydrous) gave the small osmose of 13 and 14 nis. at 63O in two experiments. A full series of observations was made by means of the osmometer F used above with sugar but with the osmotic septum of course changed.TABLE V1.-Sulphate of Magnesia in Osmometer F of double membrane for five hours. I. 11. v. VI. VII.- Sulphate of magnesia (anhSdrous) Rise in millimeter degrees. Sarqe in ;rammes oj water. Diffusate of salt in grammes. Previous naceration. Hydro-static asistance Cempera-t we,Fahr. per ccnt. 2 30 1.254 - days.2 min. 10 0 72 2 33 1.868 0.2G5 1 10 70 5 7.1 3.078 0 510 1 10 67 5 76 8 192 0.553 1 10 67 10 158 6.384 1.020 1 10 67 10 134 5.529 O*YG2 1 10 67 20 238 9.9 18 1.623 10 15 64 20 283 11.836 1.687 1 3.5 64 1 23 0-969 0.219 1 5 68 1 20 0-855 0.120 1 5 65 2 30 1-254 0.227 1 5 65 2 29 1-197 0.283 I 5 64 5 69 2.907 0.490 2 6 66 5 68 2'850 0.485 1 6 67 10 10 132 140 5.529 5'87 1 0,959 0.845 2 1 6 6 67 69 20 277 11.628 - 1 6 70 20 29 1 12'108 2,012 a 6 70 PROFESSOR GRAHAM ON The diffusate increases in a somewhat less ratio than the proportion of salt in the osrnometer in both of the two series of observations con- tained in the preceding Table.But a similar falling off in the amount of diffusate from the higher proportions of salt takes place in the diffusion of the same salt from open phials as appeared in former experiments on the diffusion of sulphate of magnesia." The different solutions then operated upon and the ratio between the diffusates they gave were as follows :-Solutions of srIphate of mag-desia diffused . . 2 4 8 16 24per cent. Ratio of diffisate of these solutions . . 2 3.671 6.701 11-785 ism8 The proportions of sulphate used in the present osmotic experi- ments were different but ratios may be found for them by interpolation and are given below.We are thus enabled to make the following comparison of the diffusion from different proportions of sulphate of magnesia (1) in the abselice of membrane; (2) in the first series of osmotic experiments given in the preceding Table; (3)in the second series of observations of the same Table :-Sulphate of magnesia in solution . . 2 5 10 20 percent. (1) Ratio of diffusates without membrane 2 4.43 8-21 13.73 (2)Ratio of diffusates with membrane . 2 4.12 7.48 12.b (3)Ratio of diffusates with membrane . 2 4.24 7.82 17.34 If the last number (17-34)given for the 20 per cent. solution of the later osmotic series be excluded and it is manifestly in consider- able excess froin some accidental cause the three sets of ratios must be allowed to exhibit considerable agreemelit.The membrane appears to have a slight effect in reducing the diffusates of the higher proportions of salt; and this reduction is greater in the early experiments (2)than iii the late experiments (3), made with the same osmometer. The comparative diffusion of different proportions of sulphate of magnesia appears therefore not to be much deranged by the intervention of membrane. The average osmose of sulphate of magnesia likewise exhibits a pretty uniform progression. In the first series of experiments of Table VI. we find for the different proportions of salt in solution an osmose of 31.5 74.5 143,and 260.5 ms.; numbers which are in the ratio given below :-Sulphate of magnesia in solution . 2 5 10 20 per cent. Ratioof osmose (firstseriesof experiments) 2 4973 9-08 16-54 In the later experiments of the same Table the different proportions of salt (omitting the first and last proportions) give an average osmose of 29*5,68*5 and 136 ms.,of which the ratios may be stated as follows Sulphate of magnesia in solution . . 2 5 10 per cent. Ratio of osmose (second series of experiments) 2 4-64 9.22 * Phil. Trans. 1850 p. 822. OSMOTIC FORCE. The osmose appears here to follow more closely in its value the proportion of salt in solution than the diffusate can be said to do either in open vessels or through membrane; so far therefore the osmose and diffusate do not preserve a constant proportion to each other with this salt.No correction need be applied to the observed osmose of sulphate of magnesia as this salt does not sensibly increase the bulk of the water in which it is dissolved. The weight of diffusate in Column IV. may therefore be immediately compared with the weights of water in Column 111. It then appears.that in the first series of the osmotic observations in the Table- In 2 per cent. solution 1 sulph. magnesia is replaced by 5.16 water. In 5 per cent. solution 1 sulph. magnesia is replaced by 5-74water. In 10 per cent. solution 1 sulph. magnesia is replaced by 6.01 water. In s?O per cent. solution I sulph. magnesia is replaced by 6-57 water. According to the average of the whole proportions sulphate of magnesia is replaced by 5 87 times its weight of water.While in the later observations of the same Table- In 2 per cent solution 1 sulph. magnesia is replaced by 5.33 water. In 5 per cent. solution 1 sulph. magiiesia is replaced by 5.9 water. In 10 per cent solution 1 sulph. magnesia is replaced by 6-32 water. According to the average of the whole proportions of salt in these Iater observations sulphate of magnesia 1s replaced by 5-85times its weight of water. The want of uniformity exhibited above in the relation between the quantities of water and salt goes some way to prove that the osinose of sulphate of magnesia in membrane is not pure diffusion for the ratio between the exchanging water and salt (the d@usion-voZzcrnes) should then remain constant.On the other hand the approxiniation to uniformity favours the idea of the existence of a numerical relation between the osmose and diffusate. So also may the circumstance be considered that sugar and sulphate of magnesia which approximate as seen above in thcir osmose were found before to have a similar degree of diffusibility.* The facts appear to afford a strong presumption but no demonstrative proof of the intervention of diffusion in governing the results of osmose in such neutral substances. The influence of diffusion becomes more difficult to trace in the osmose of three other neutral salts which I shall now introduce. What has been represented as the chemical agency now begins to interfere more sensibly although not to govern the results entirely as it appears to do in less strictly neutral salts.Chloride of Sodium.-The osmose of chloride of sdum possesses a certain interest independently of such theoretical considerations. * Phil. Trans. 1850,p. 10. 70 PROFESSOR GRAHAM ON TABLE VIL-Chloride of Sodium in Osmometer C of double membrane for five hours. I. 11. 111. IT. V. VI. VII. Chloride Rise in Same in Diffusste of t'empera-Of millimeter gramrnes of salt in Previous €ydroststic ture sodium. degrees. water. grammea. maceration. resistance. Fahr. 0 per cent. days. min. 0.25 12 0.552 -2 16 63 0.26 8 0.368 0.008 1 16 (3.3 1 3 0 138 0-230 1 6 66 1 13 0.598 0'242 1 8 66 2 11 om6 0.506 1 6 ti7 2 16 0.736 0.51 1 1 3 6!) 5 4G %34 1.513 2 3 72 5 51 2.30 1.468 1 2 71 20 78 3.496 2.994 1 15 67 10 82 8160 2'648 1 2 67 20 165 7-36 6'645 I.2 67 20 167 7.452 6-190 1 2 67 Chloride of sodium is known to diffuse with nearly double the rapidity of sulphate of magnesia in the smaller proportions of salt and with a still higher velocity in the larger proportions of salt; accordingly the diffusates in the last Table exceed those of sulyhate of magnesia in a corresponding ratio. The osmose appears pretty uniform but with a tendency to fall below the average rate of the salt in the low proportions such as 1and 2 per cent. and to exceed the same rate in the higher proportions of salt. In a septum of single membrane the osmose of a 10 per cent. solution was observed to rise to a high amount.TABLE VII1.-Chloride of Sodium in Osmometer H of single membrane for five hours. I. I 11. I 111. IT. v. I VI. 1 VII. Salt Rise in Same in DXusate of Previous Hydrost,atic 1 TeE::,ra-in millimeter grammes of salt in maceration. resistance. solution. degrees. water. grammes. Fahr. --1 ~~~ per cent. day. min. 1 2 21 1.04 0.9 1'7 1 16 2 24 1-20 0.956 1 16 68 10 272 13.28 6.502 1 16 10 I 311 15.68 7.850 1 13 ;6 OSMOTIC FORCE. An observation was made on the osmose of a high proportion of salt with another single membrane differing from the last in offering considerably less hydrostatic resistance. TABLE 1X.-Chloride of Sodium in Osnionieter I of single membrane for five hours.I. 111. IV. --11. ---Salt Rise in Same in Diffusate of in millimeter grammes of salt in solution. degrees. water. grammes. per cent. 10 198 1 10 LO4 To these I add a series of observations of the osmose of the same salt in albumen with the view of exhibiting the phenomenon in septa of that material. The well-preserved proportionality of the diffusate is remarkable. TABLE X.-Chloride of Sodium in Osmometer K of albuminated calico for five hours. per cent. 1 1 16 27 - 0.141 0.219- days. 4 1 min . 8 8 0 65 62 4 39 CI 1 2 GO 4 34 - 0.625 3 2 56 10 10 10 43 61 72 -- 1.580 1-615 1.597 1 1 1 3 3 3 50 60 61 I 27 - 0.153 I 2.5 63 1 0.1 0-1 22 27 29 -- 0-141 0-016 0.018 2 1 1. 4 2.5 4 63 03 64 Chlorideof Barium.-Chloride of barium in its rate of diffusion from open vessels much resembles the chloride of sodium.Con-siderable analogy between the same salts is also observed in osmotic experiments. 72 PROFESSOR GRAHAM ON TABLEXI.-Chloride of Barium in Osmometer L of double men1brane for five hours. V. I. 11. I 111. IV. ---VI. VII. Salt Rise in Same in Diffusate Previous 3sdrostatic 'empera-in ture, in millimeter grammes of gra:n mes. naceration. resistance. Fahr. solution. degrees. water. --0 per cent. daj 8. min. 8 35 1.476 -2 .I0 52 2 45 1*8B6 0.675 1 10 70 5 94 3.930 1.708 1 8 (5 7 5 111 4 074 1.040 1 6 67 5 74 3-116 1.203 1 10 07 20 154 6.478 449 1 1 10 67 10 133 5'376 3'895 10 26 64 10 1% 3'74 2'92'3 I 4 64 20 2u7 1 1.2 14 6-860 1 8 08 20 283 11.79 7'030 1 b 65 1 60 2'542 0'275 1 8 65 1 'id 3'1 16 0'230 1 8 04 5 74 3'118 0-602 2 8 tici 5 74 3.116 1.887 1 9 67 10 162 G-396 3'795 2 8 67 30 15i 6'478 4.040 1 8 69 20 337 14-186 -1 8 70 20 320 13-448 8.130 1 8 70 TABLE XI1.-Chloride of Calcium in Osmometer M of double membrane for five hours.I. 11. 111. IT. v. -VI. VII. salt Riee in Same in Diffusate Previoue [ydrostatic 'empera-in millimeter 5rammes of lIl maceration. resis trance. ture solution. degrees. water. grammes. Fahr. 0 per cent. days. min. 2 6 0.258 -2 8 72 2 6 0.258 0-795 1 8 70 I) 45 1.935 2'29 1 8 67 5 60 2'64 1-88 1 3 67 5 51 2'24 2'636 1 8 67 10 228 9.92 4'256 1 8 67 10 188 8.24 3'607 10 13 64 10 176 7.76 3.11 1 6 64 20 389 17'2 6.075 1 3 68 20 398 17.6 -1 3 65 2 24 1'04 0.668 1 4 G5 2 27 1'2 0.625 1 4 64 5 81 3'6 1-51 2 2 5 66 5 s3 3'68 1'467 1 5 67 10 185 8'16 3'158 2 5 67 10 IS2 8 8'317 1 5 69 20 406 18 6.695 1 5 70 20 416 18.4 6.992 1 3 70 OSMOTIC FORCE.Chloride of Calciurn.-The diffusion of chloride of calcium in open vessels has been observed to fall below that of chloride of barium as 7-5 to 6.5." But in membrane judging from the following observations the diffusion of chloride of calcium is the more rapid of the two. The osmose has also a tendency to rise particnlarly in the larger proportions of chloride of calcium. The replacing water often exceeds twice the weight of the salt diffused. (See Table XIT. p. 73.) These three chlorides.possessing about double the diffusibility of sugar and sulphate of magnesia should bereplaced by half as much water as the latter substances. Some approach to this ratio may be perceived amid niuch irregularity in the observed osrnose of the chlorides. Proceeding now to the salts in which the osmose appearing to depend upon chemical properties preponderates greatly over osmose from diffusion T may introduce these substances under the metals which they contain for the sake of their relations in composition. POTASSIUM AND SODIUM. Hydrate of Potash.-A highly intense osmose appears to be determined by caustic alkali but it is necessary to apply the smallest proportions of alkali to avoid the rapid dissolution of the membrane.In double membrane 0.01 per cent. of hydrate of potash or 1 alkali in 10,000 water gave an osmose of 61 and 58 ms. By four times as much alkali or 0.025 per cent. an osmose of 49 and 67 ms. was produced. These are the greatest effects. On increasing the proportion of hydrate of potash to 0.5 per cent. the osmose sunk to 22 and 26 ms.; with 1 per cent. of hydrate of potash to 13 ms. The permeability to hydrostatic pressure was always very great being never less than one drop in a minute. By the action of the alkali in the last experiment the permeability was increased from three to nine drops and the membrane entirely ruined. A similar experiment with hydrate of potash was made in albuminated calico with similar osmotic results. In the 0.01 per cent.solution an osmose of 76 and 58 ms. was observed; in 0.025 per cent. solution 87 and 126 ms.; in 0.5 per cent. solution 15 and 12 ms. ;and in 1 per cent. solution -lOms. or a small negative osmose. The permeability both before and after the last experiment was represented by one drop in one minute; in both the half per cent. experiments the permeability was one drop in three minutes; in the preceding 0.025 per cent. solutions one drop in 24 minutes and at the beginniug one drop in ten and five minutes with the 0.01 per cent solutions. The alkali first became sensible to the test-paper in the water-jar in the diffusion of the 0.025 per cent. solutions. During both series of experiments the temperature ranged from 58' to 62'. Carbonate of Potash.-The high osmose of this salt bas already * Phil.Trans. 1850,pp. 817 819. 74 PROFESSOR GRAHAM ON been often referred to in illustration of the influence of alkaline salts. The following experiments may be compared with those upon the neutral substances lately discussed particularly in regard to their diffusates. They show also the comparative influence of membrane applied single and double to an osmometer. TABLE XII1.-Carbonate of Potash in Osmometer B of single membrane for five hours. I. IV. v. VI. VII. 11. 111. ----PI-Propor-Rise in Same in millimeter grammes of Diffusate in Previous Hydrostatic Tempera-tion grammes. maceration. resiatance. ture of salt. degrees. water. Fahr. --_I__---0 per cent. day. min. 2 635 28.676 0.514 1 20 66 2 695 31.256 0.548 1 20 68 10 892 40 128 2.897 1 16 68 10 900 40.508 I 3.045 I 1 I 16 I 68 third hour and replaced by distilled water to prevent the reaction of that portion of the salt which had already reached the jar upon the progress of diffusion from the osmometer both in the preceding and the following series of experiments.TABLE X1V.-Carbonate of Potash in Osmoineter D of double membrane for five hours. I. 1 11. 1 111. 1 IV. I v. j VI. 1 VII. .--A -Propor-Rise in tion millimeter of salt. degrees. --7 0 per cent. day. min. 2 449 21.683 0.324 1 10 66 2 484 23.621 0.400 1 16 68 10 619 30.178 2.764 1 16 68 10 595 28.993 3.150 1 12 68 In the double membrane the average ostnose of the 2 per cent.solution is reduced to 466 ms. from 665 ms. in the single membrane. The change is similar in the 10 per cent. solution namely a reduction to 607 from 896 ms. ; a reduction of nearly one-third of the osmose in the double membrane for both proportions of salt. The difference of the diffusates is much less marked; for they OSMOTIC FORCE. may be said to be the same for the 10 per cent. solutions namely 2.966 grms. in the single and 2.957 grrns. in the double membrane; and for the 2 per cent. solution 0.531 grm. in the single and 0.326 grm. in the double membrane. The diffusion of carbonate of potash as seen here in membrane will be found to correspond well with that of chloride of sodium (Table VII.) as the diffusion of the same two salts in open vessels is known to present a near approach to equality.The great osmose or current of fluid inwards might be supposed to diminish the outward movement of the salt under diffusion by washing back the salt into the osmometer. But the diffusates of the 10 per cent. solutions appear to have suffered uo remarkable reduction from that or any other cause. The diffusate of carbonate of potash which usually passes through membrane appears however to be low In the 1 per cent. solution formerly referred to it was 0.195 grm. In the series of observations likewise already referred to the diffusate of carbonate was also low but remarkably uniform namely 0.018 grni. for 0.1 per cent. solution 0.092 grrn. for 0.5 per cent. solution and 0.196 grm. for the 1per cent.solution. But these determinations were all made by the alkalimetrical method and when in subsequent observations the potash was also determined by weighing it as sulphate the proportion of diffusate was found sensibly increased. It hence appears that carbonate of potash acts chemically upou the membrane and that a portion of the alkali diffuses out in a neutralised state. Thus in five successive experiments with the 1 per cent. solution in fresh double membrane the diffueates by the alkalimetrical method were 0.208 0.254 0.264,0.215 and 0.189 grm. carbonate of potash; while the actual quantity of alkali found by direct analysis corresponded in the last four observations to 0.318 0.353 0287,and 0.242grm. The quantity of carbonate of potash which has suffered change in passing through the membrane is 0.064 0*089 0.072 and 0.053 grm.in these four experiments respectively. The diffusates of carbonate of potash increased by those quantities approach too closely to those of chloride of sodium to warrant the supposition of any peculiar repression by membrane of the diffusion of carbonate of potash which otherwise appeared probable. The observations last commented upon belong to a nnmber under- taken with the view of ascertaining three points of interest which may excuse a fuller statement of the experiments. These points were first the influence upon osmose of the air dissolved in solutions of carbonate of potash which might be supposed to take a part in the chemical action of the membrane ; secondly the effect of frequent repetition of the experiment in exhausting the osmotic activity of metnbrane; and thirdly the relation in osmose of an alkaline carbo- nate and phosphate.PROFESSOH QRAH AM ON TABLE XV.-Solutions in Osrnometer L of double membrane for five hours. Rise in Tempera-Salt in osmometer. millimeter ture Fahr. degrees 0 Carbonate of potash 1 per cent. ........ 439 63 Same deprived of air by boiling ........ 376 64 Same deprived of air by boiling ........ s53 65 Same solution unboiled ........... 325 63 Same solution uiiboiled . ........ 268 56 Phosphate of soda (2NaO €iO PO,) 1 per cent. ... 1.76 55 Same ....... 194 58 Same 0.1 per cent. ...... 190 56 Same 0.1 per cent....... 1so 0n Carbonate of potash 0-1per cent. ....... 176 57 Same 0.1 per cent. ...... 227 65 Same 1 per cent. ...... 208 58 Same I per cent. ...... 335 64 Same 1 per cent. ...... 312 62 It will be remarked that the highest osmose (439ms.) is obtained in the first experiment and that the osmose falls off pretty regu- larly to the fifth experiment (268 ms.) The change in the aeration of the solution in the second aud third experiments cannot be said to interfere with this progression. The influence of free oxygen on the membrane is not therefore indicated as a cause of osmose. It may be added that the converse experiment of depriving the fluid of the water-jar of air by boiling led also to a negative result. It will be remembered further that the osmose of oxalic acid was not interfered with by an addition of sulphurous acid which was likely to counteract the action of oxygen if such an action existed in osmose.When phosphate of soda is substituted for carbonate of potash both 1 per cent. the osmose declines from 268 to 176 ins. The phosphate of soda being repeated the osmose rises a little namely to 194 ms. The one-tenth per cent. solution of the same salt which follows main- tains here the considerable osmose of 196 and 190 ms. On returu-ing again to the application of carbonate of potash in the instrument the osmose gradually rises and regains 335 ms. for the 1per cent. so-lution of that salt. From these repetitions of osmose it may be inferred that whatever be the nature of the chemical action on membrane which prompts os-mose that action is by no means of a rapidly exhaustible character.It may be added with regard to the osmotic action of extremely dilute solutions of carbonate of potash that the osmose is lowered rapidly in proportions bclow one-tenth of a per cent. of that salt. The osmoseof 0.01 per cent. of carbonate of potash in double mern- brane aiiiounted only to 19 23 and 17 ms.in three successive experi- OSMOTIC FOitCE. 77 ments. The osmotic action of carbonate of potash must therefore be inferior to that of hydrate of potash in the extreme degrees of dilution. In the experiments of the preceding series the influence of a salt often appears not to terminate with its presence in the osmometer but to extend to following experiments made with other salts or made with different proportions of the original salt.If this arises from portions of the first salt remaining in the membrane they must be portions which are not easily washed out. The substance of membrane may possibly have an attraction for highly osmotic salts capable of with- drawing small quantities from solution. When the membrane how- ever is removed from the osmometer after such experiments as are referred to slightly washed and then incinerated only minute traces of the salt last used are commonly discovered; if indeed the salt has not entirely disappeared. Phosphate and Carbonate of Soda.-The osmose of the carbonate of soda appears to be quite similar to that of carbonate of potash.A considerable amount of information respecting the two soda-salt s named is conveyed in thefollowing series of experiments which include s also observations on the serum of ox-blood. TABLE XV1.-Solutions in Osmometer F of double membrane for five hours. Rise in Salt in osmometer. millimeter Tempera-degrees. ture Fahr* 1 1-0 Phosphate of soda 1 per cent. ......... 312 65 Same 1 per cent. ............. 31 I 56 Same. 0.1 per cent. ............ 205 55 Same 0.1 per cant. ............ 218 58 Carbonate of soda 0.1 per cent. ........ 294 RA Same 0.1 per cent. ............ 251 58 Same 0.01 per cent. ............ 50 57 Same 0.01 per cent. ............ 39 65 Same 1 per cent. ............. 306 58 %me 1 per cent. .............337 64 Phosphate of soda 1 per cent. ......... 193 62 Same 1 per cent. ............. 186 61 Serum of ox-blood nndiluted ......... 39 59 Same ................. 3-1 61 Same diluted with equal vol. of water ...... 31 61 The phosphate and carbonate of soda when alternated in the same osmometer show considerable steadiness in their respective rates of osrnose. The inferior osmotic quality of serum is remarkable considering the alkalinity of that fluid. The loss of osmose in serum is due I PROFESSOR GRAHAM ON believe to the presence of chloride of sodium. The latter substance possesses an extraordinary power of reducing the osmose of alkaline salts which was observed in a variety of circumstances but which it will be sufiicient to illustrate by the following series of experiments in an albumen osmometer.TABLE XVI1.-Solutions in Osrnometer N of albuminated calico for five hours. Rise in Diffussbe Previous Hydro-Tempera-Salt in osmometer. aillimcte igramma macera-static t,ure degrees. y analysis tion. *esistancc Fahr. days. min. Carbonate of soda. lpercent 139 0.1317 0-092 1 3 07 Same 1 per cent.. . . . 1so 0.156 O-lO(i 1 6 59 Same 2 percent.. . . . 141 0-242 1 6 65 Same 4percent.. . . . 143 0.570 -1 8 02 Same 10 per cent. . . . 204 1.502 1’450 1 12 SO Same 10 per cent. . . . 163 1.432 1-3dO 3 6 56 Same 1 per cent.. . . . ,138 0.216 0. I47 1 6 59 Same 1 per cent.. . . . 136 0.198 0.156 1 3 60 Same 0.1 per cent. . . . 188 -0.005 1 10 61 Same 0.1 per cent.. . . 179 -1 6 63 Carbonate of soda 0.1 per cent. +chloride of soda I 32 -2 6 63 1 per cent. . . . . .j Same+same . . . . 36 -1 6 GR Chloride of sodium lpercent 25 0.384 -1 0 64 Same 1 per cent. . . . . 18 0-325 1 3 Ci5 Carbonate of soda 1 per’ cent. +chloride of soda 69 -1 5 63 1 per cent. . . . . 1 -Same + same . . . . . 56 3 8 56 Carbonate of soda 1 per cent 167 0.190 0.164 1 G 65 Same 1per cent. . . . . 163 0.212 0-185 1 4 58 Same 0.1 per cent. . . . 152 -1 20 66 Same 0*1per cent. . . . 152 -1 20 68 The osmose of the 0.1 per cent. solution of carbonate of soda is lowered by the addition of 1per cent. chloride of sodium from 179 ms. to 32 nis. The osmose of 1 per cent. carbonate of soda with the addition of an equal proportion of chloride of sodium is 56 ms.and of 1 per cent. carbonate of soda alone immediately following 157 ms. The osmose of these mixtures appears to be assimilated to that of chloride of sodium itself which comes out as 18 and 25 ms. in the same series of observations. The rise of an alkaline liquid in the osmometer appears to be equally repressed by chloride of sodium placed outside or dissolved in the fluid of the water-jar. In illustration of this statement I may adducc a short series of OSMOTIC FORCE. Rise in Salt in osmometer. millimeter degrees. Carbonate of potash 0.25 per cent. ........... 76 Same 0.25 per cent. ................ 06 Carbonate of potash 1 per cent. a.gaiust alcohol 1 per cent. in jar 108 Same 1 per cent.against sugar 1 per cent. in jar ..... 104 Same 1 per cent. against chloride of sodium 1per cent. in jar . 18 Same I per cent. against pure water in jar ........ 114 Same 1 per cent. against chloride of sodium 1 per cent. in.jar . 18 Carbonate of potash 1 per cent. +chloride of' sodium 1per cent. against water in jar ............... 64 Carbonate of potash 1 per cent. alone against pure water in jar 134 Same repeated .................. 114 Now another neutral salt sulphate of potash will be found to have the reverse effect upon the osmose of an alkaline carbonate support- ing and promoting the latter. Such results show how far we still are from a clear comprehension of the agencies at work in membra- nous osmose. Another property of chloride of sodium equally singular is that the association of this salt (by itself so indifferent) with small proportions of hydrochloric acid such as one-tenth per cent.deter- mines a positive osmose in membrane which is sometimes very considerable. The osmotic action of the alburninated calico of Table XVII. is moderate in amount but remarkably uniform. The small tenth per cent. solution assumes a preeminence in activity which is very curious. It was often observed in the inquiry that the small proportions of active salts were more favoured in albuniinated calico than in mem- brane; may it not thence be inferred that it is in the albumen plate that the chemical agency operates to most advantage ? Taking the mean cliffusates of chloride of sodium and carbonate of soda from the lower part of the same Table we have 0.354 chloride of sodium against 0.201carbonate of soda or 1 of the former to 0.568 of the latter.The diffusates of the same two salts in open vessels were more nearly in the proportion of 1 to 07. The compa- rative diffusion of carbonate of soda appearsto be rather repressed than promoted by the septum. The neutralisation of a portion of the alkaline salt during the 0s- 80 PROFESSOR GRAHAM ON niotic process is again indicated. The portion of carbonate of soda thus lost in the 1 per cent. solution appears to diniinish on repetition of the experiment. At the head of the Table the loss iu two experi- ments is 0.065 and 0.050 grm. ; lower down 0.069 and 0.042grm. ; and near the bottom of the Table 0.026 and 0.027 grm.The loss with the 10 per cent. solution is 0.110 and 0.092 grm. or not more than double the loss in the preceding 1 per cent. solutions of carbo-nateof soda. Subhates of Potash and Soda.-The sulphate of potash was made the subject of frequent experiment with the view of obtaining light on thenature of osmose at the commencement of the inquiry. But it is not well fitted for such a purpose its action in the ostnonieter proving at first of a most perplexing character. With thick ox-bladdz sulphate of potash dissolved in the proportion of 1 per cent. usually exhibited considerable osmose ; that is about one-half of the osniose of carbonate of potash in similar circumstances. The osmose of the sulphate had however a peculiar disposition to increase in successive repetitions of the experiment with the same membrane.The osmose of this salt might also be doubled by allowing bladder in substance to macerate for some time in the solution before the osmotic experiment soluble matter from the membrane manifestly influenced the result considerably in all experiments with sulphate of potash. When the removal was effected of the muscular coat of bladder the chief source of its soluble matter the osmose of the salt in question fell greatly in amount instead of rising like that of the carbonate of potash. In the prepared membrane sulphate of potash presented a small moderate osmose like chloride of sodium. But the salt niust be ex- actly neutral to test-paper and the membrane also free from foreign saline matter otherwise very different results are obtained.In a double membrane 1 per cent. of the neutral sulphate gave 21 and 20 ms. ;but the same solution made alkaline by the addition of no more than one ten-thousandth part (0.01 per cent.) of carbonate of potash started up to 101 and 167 ms. a much greater osmose than the proportion of carbonate of potash present gave afterwards by itself in the same membrane namely 19 23 and 17 ms. The influ- ence of the alkali is so persistent that the membrane macerated in water for a night after the last experiments still gave 65 ms. with 1 per cent. of pure sulphate of potash. The osmotic activity of sulphate of soda is equally excited by a trace of alkali and both sulphates exhibit the same character in albu- men as well as in membrane.This remarkable result of the combined action of the two salts is so likely to elucidate the chemical actions prevailing in osmos? that a fuller series of illustrative experiments may he recorded. The septum was of double calico well albuininated and presented a good resistance to hydrostatic prcssure. OSMOTIC FORCE. 81 TABLE X1X.-Solutions in Osmometer Q of albuminatcd calico for five hours. Rise in Tempera-Salt in osmometer. millimetei t ure degrees . Fahr. 0 Sulphate of potash 1 per cent. .... ..... 1s 53 Same .................. 21 57 Sulphnte of potash 1 per cent. +carbonato of potash 0-01per cent. ............... 189 62 Same +same ...............81 36 Same +same ............... 73 61 Same +carbonate of potash 0.1 per cent. ...... 254 01 Same -+sam0 ............... 263 59 Carbonate of potash 0.1 per cent. alonn ...... 92 57 Carbonate of potash 0.1 per cent. alone ...... 95 57 Sulphate of soda 1 per cent. +carbonate of potash 0.1 percent. ................ 2.57 62 Same +same ............... 237 54 Saine +carbonate of soda 0.1 per cent. ...... 294 54 Carbonato of soda 0 I per cent. alone ....... 90 5’7 Same .................. 127 58 The influence of the two alkaline carbonates in giving a high osrnme to the sulphates appears to be pretty nearly equal. The primary source of the great osniosf may prove to be the action on membrane of the alkaline carbonates which is promoted in some way by the presence of sulphate of potash as it is retarded by the presence of chloride of sodium.On the other hand the moderate amount of osmose which appears to be proper to these sulphates is completely negatived by the most rniiiiite addition of a strong acid. Thus 1per cent. of sulphate of potash with the addition of one ten-thousandth part (0.01per cent.) of hydrochloric acid had its osniose reduced in the first experiment to 8 ms. and in the second experiment to -5 ms. the osmose be-coming actually negative. On one occasion a specimen of well-ciystallised sulphate of potash gave when dissolved a still more sensible negative osinose namely -28 ms. On applying litmus to the solution it was found to possess an acid reaction. But the addition of 0.01 per cent.carbonate of potash was suficient to change thc acid into an alkaline reaction and to give rise to a positive osmose amounting to 54 ms. It occurred to me to macerate a fresh menibmne in water contain- ing one-thousandth part (0.1 per cent.) of hydrochloric acid for two days before applying the niembrane to the osmometer and then to wash the membrane with distilled water till all acid reaction’disappeared. With 1per cent. of neutral sulphate of potash this menibrane gave in succession 17 442 35,and 62 ms. ;with sulphate of soda 1 per cent. following 30,25,and 25 ms.;and with sulphate of zinc (anhy- VOL. VIII. --NO. XXIX. G PROFESSOR GRAHAM ON drous) 1per cent. after the last sa!t 14 and 21 ms. These last results show a certain degree of' unsteadiness in the osmose of the alkaline sulphates probably arising from the osmose of these salts depending so much upon adventitious circuinstances.The diffusates were carefully weighed first when fully dried at 2124 and again when ignited. The difference in the wcighings arose from the presence of organic matter dissolved out of the membrane of which it gives the quantity probably somewhat exaggerated. First diffusate 0.328 grm. sulphate potash. Second diffusate 0.362 grm. sulphate potash 0.019 organic matter. Third diffusate 0.351 grm. sulphate potash 0.031 organic matter. Fourth diffusate 0.366 grm. sulphate potash 0.025organic matter. Fifth diffusate 0.356 grm. sulphate soda 0.011 organic matter. Sixth diffusate 0.339 grm.sulphate soda 0.019 orsanic matter. Seventh diffusate 0.334 grm. sulphate soda 0.009 organic matter. Eighth diffusate 0.239grm. sulphate zinc. Ninth diffusate 0.260grm. sulphate zinc. The diffusates of the two alkaline sulphates are remarkably uniform the diffusate of sulphate of soda falling a little under that of sulphate of potash but not so much as in open vessels. The diffusate of sul-phate of zinc is still smaller but relatively too high as it should not much exceed one-half of that of sulphate of potash judging from the diffusion of these salts in the absence of membrane. The organic matter accompanying the salt falls off in quantity in successive experi- ments but continued to exist to the last although it was not deter-niiried in the experiments with sulphate of zinc.The diameter of the disc of membrane was 123 millimeters and its original weight air- dried 0.559 grm. Oxalate of Potash Chromate and Bichrornate oj Potash-The only property of sulphate of potash which seems to be connected with the positive osmose of that salt is its bibasicity as a sulphate. The alkaline character promotes positive osmose and this character appears to be a distinction of polybasic salts The common tribasic phosphate of soda is strongly alkaline to test-paper and the bibasic pyro-phosphate of soda enjoys the same property in a still higher degree. The sulphates of potash and soda are certainly neutral to test-paper but they may be looked upon as potentially alkaline froni the easy severation of the second equivalent of fixed base and its replacement by water witnessed in all bibasic salts.In monobasic salts on the contrary a proclivity to the acid character may be suspected. Thus although the chloride of potassium and nitrate of potash appear as neutral to test-paper as the sulphate of potash ig yet the chlorides and nitrates of the magnesian bases are more decidedly acid than their sulphates. It is just possible then on this view that the osmotic infe- riority of chloride of sodium and the power of that salt to counteract the positive osmose of carbonate of potash may be exhibitions of acid character belongiug to the former salt. The observations of the rise OSMOTIC FORCE. in the osmonieter of chloride of sodium and also of the chlorides of barium and calciuni previously described also have the appearance of being the effect of diffusion modified by a slight chemical osmose of a negative character proper to these salts.The polybasic coiisritution of oxalate of potash is well marked and its positive osmose will be found below to be considerable although the specimen of salt employed was strictly neutral to test-paper. This salt also like sulphate of potash is shown not to counteract the high positive osmose of an ailtalifie carbonate. The chromate of potash although carefully purified by crystallisa-tion retained a slight alkaline reaction. On this account small addi- tions were made to it of bichrornate of potash in some experiments but without materially diminishing the very sensible positive osniose of the former salt.A neutral chromate has of course the same bibasic character as a sulphate. TABLE XX.-Oxalate and Chromate of Potash in Osmometer F of double membrane for five hours. Solution of salt. Rise in ninimete Previoue macera- Hydro-8tatic Tempera-ture degrees. tion. --_ esistance Fahr. 1 per cent. osalate of potash ... Same........... 164 153 days. 1 1 min. 11 10 0 65 ti .5 0.1 per cent. osalate of potash . . Sante ........... 1 per cent. oxdate of potash +0.1 per cent. carLonate of potash .. Same +same ........ 92 90 262 337 1 2 8 1 5 6 5 5 63 Bi 58 60 0.1 per cent. carbonate of potash . Same ........... 1 per cent. oxalate of potash +0.1 per cent. carbonate of potash . . Smie +same ........ 322 273 294 246 1 1 1 2 3 3 3 3 62 68 62 55 1 per cent.bichrornate of potash . Same ........... 24 19 1 2 3 1 54 56 1 per cent. chromate of potash . . Same ........... 109 106 1 1 1 1 82 58 1 per cent. chromate of potash =0.1 bicliroinate of potash .... Same ........... 91 3!) 2 1 1 I 57 6in The average rise for the 1 per cent. solution of each of the salts placed in the osmometer in a pure state is bichromate of potash 21.5 ms. chromate of potash 107.5 ms. and oxslate of potash 138.5 ms. The average diffusate for the chromate of potash is 0.3165 grm. and for the bichromate of potash 0.2855 grm. Like solutions were submitted to osmose at the same time in a sep- tum of albumen for the sake of comparison with the preceding memo brane osmometer. PROFESSOR GRAHAM ON TABLE XX1.-Oxalate and Chilomates of Potash in Osmometer K of albuminated calico.Solution of salt Rise in iillimetei iiegrees. ?revious macera-tion. Hydro-static esiatance rempera-ture Fahr. 1 per cent. oxalate of potash . . Same ........... 195 173 days. I 1 min. 15 15 0 65 65 0-1 per cent. oxalate of potash .. Same ........... 1 per cent. oxalate of potash +0.1 per cent. carbonate of potash .. Same +same ........ 91 I00 161 211 1 2 8 1 15 20 15 16 63 60 56 60 0.1 per cent. carbonate of potash . Same ........... 1 per cent. oxalate of potasb +0.1 per cent. carbouate of potash .. Same +same ........ 109 120 195 188 1 1 1 2 15 25 15 15 62 68 63 55 1 per cent. bichromate of potash . Same ........... 36 34 1 2 15 10 54 56 1 per cent.chromate of potash .. Same ........... I per cent. chromate of potash +0.1 per cent. Licliromate of potash . Same ........... 129 123 95 I02 1 1 2 I 13 10 10 10 62 58 07 ti0 The average rise for the 1 per cent. solution of each of the salts is for bichroniate of potash 35 ms. for chromate of potash 126 ms. and for oxalate of potash 184 Ins. all a little higher than in the previous membrane osmometer. The diffusate is lower than before probably owing to the less permeability of the albuminous septum the weight of chromate of potash diffused being 0-2475 gramme and of bichro-mate of potash 0*24<4 gramme. T4e two chromate8 have been found to possess nearly equal diffusi- bility in open vessels and to correspond closely in that property with sulphate of potash.The oxalate of potash exhibits a considerable osrnose when present in the small proportion of one-thousandth part (0.1 per cent.) namely 91 ms. in membrane and 95.5 ms. in albumen. This is the surest indication of considerable osmotic capacity. Bin-oxalate of potash and free oxalic acid are both remarkable for high negative osmose. Barium Strontium Culciurn Magnesium.-The salts of these metale never appear capable of producing strong positive osmose when dissolved in a proportion of less than 1 per cent. On the contrary some of the salts of this class particularly the nitrates exbibit a ten-dency to negative osmose. Hydrate of Baryta gave a small positive osmose for minute pro-portions of salt which disappeared as the proportion of salt was in-creased exhibiting an analogy in this respect to hydrate of potash.The results for hydrate of baryta in double membrane n-ere 6 4,1 OSIMOTIC FORCE. and 1 degrees of osrnose for the 0.1,0-25 and 0.5 per cent. solutions. In albumen the same solutions gave 0 -8 -23 and -17 ms.; and the 1 per cent. solution gave -25 ms. Hydrate of Lime exhibited similar characters to the last base. Undiluted lime-water gave in double membrane -20 ms. and -1 IYI. ; while the earne diluted with four volumes of water gave a positive osi~lose:of 31 and 18 ms. In albumen the undiluted lime-water gave -48 and -30 ms. ; the 'same diluted with four volumes of water gave 0 m. and I m. Chloride of Sirontiurn 1per cent. gave in double membrane '19 27 and 26 ms.; following chloride of barium in the same membrane 13 and 21 ms. Nitrate of baryta in the same membrane gave 12 24 and 29 ms. ; nitrate of strontia following the latter 27 and 31 MS. Nitrate oj'lime in membrane twice gave 19 ms. following chloride of calcium with 12 and 20 ms. ; in albumen nitrate of lime gave 2 and 2 ms. The 2 per cent. solution of the same salt in membrane gave only 6 and 6 ms. in two experiments. Chloride of Mu,ynesium gave in membrane -2 ms. and in albumen 6 tns. both experiments being made with the 1per cent. solution which isalways to be understood when no particular percentage is stated. Nitrate of Magnesia gave in membrane -24 and -20 ms. Both of these magnesian salts were prepared by saturating the acid with excess of magnesia.The tendency of monobasic salts of the magne- sian class to chemical osmose of a negative character appears to be small in the salts of barium and strontium to rise in those of calcium and to culminate in the salts of magnesium itself. Aluminium.-Nothing is more remarkable than the high positivi osmose of certain salts of alumina. These salts emulate the alkaline carbonates in this respect. The property too appears to be charac- teristic of the sesquioxide type and distinguishes the salts of sesqui-oxide of iron,sesquioxide of chromium and the higher oxide of uranium as well as alumina Sulphate of AZumiw.-'Phe sulphates of this type do not exhibit a high degree of osmose although they are probably more osmotic than the magnesian sulphates asa class.Sulphate of alumina 1 per cent. gave inmembrane 57 and 67 ms. and for 0.1 per cent. 24 and 31 ms. The diffusate was sniall amounting in the second observation of the 1 per cent solution to 0*(]33'gramme of tersulphate of alumina together with an excess of 0.005 grm. of sulphuric acid according to analysis. Chloride of Aluminium,.prepared by treating hydrochloric acid with an excess of hydrated alumina was found by analysis to approach very nearly to the proportions of the definite compound Al Cl,. The fol- lowing results with that salt were successively obtained in an osmo- meter of single nienibraiie :- PROFESSOR GRAHAM ON With 1 per cent. iiae of 540 ms. at 50' Fahr. With 1 per cent. rise of 570 ms.at 49' ,, With 1 per cent.rise of 450 ms. at 47' ,, With 1 per cent. rive of 635 ms. at 49' ,, With 0.1 per cent. rise of 510 ms. at 54' ,, With 0.1 per cent. rise of 285 ms. at 48' ,, With 0.1 per cent. rise of 410 ms. at :)6' ,, The numbers which are all high vary considerably among them- selves as often happens when osinose is intense and is observed in a single membrane. The temperatures of the water-jar are added in these and most other observations recorded although it was difficult to draw any positive conclusion respecting the influence of heat upon the osmose of small * proportions of salt. M'itb large proportions of neutral salts where diffusibility prevails the osmose appeared to in-crease with the temperature as does the proportion of salt diffused.With respect to the condition of the membrane used above the first experiment was conducted in the membrane freshly dissected and previous to any maceration or washing whatever with a similar osmotic result it will be observed as in the later experiuients made with the membrane after being repeatedly macerated. In experiments of diffusing chloride of aluminium in open vessels deconiposition of that salt was observed with escape of free hydro- chloric acid. The decomposition appeared however to affect much less of the chloride of aluminium than it does of the acetate of alumina. In an albumen osmometer chloride of aluminium gave an osmose of 245 233 and 229 ms, at 57' 58' and SO' with diffusates of 0,085 0,123,and 0,095gramrne of salt calculated from the quantity of chlorine found in the diffusate.In the last experiment the solution was coloured with litmus ap- parently without affecting the amount of osmose. Acetate of Alumina was prepared by precipitating pure sulphate of alumina by means of the acetate of lead. Mr. Crum has shown that in this reaction one equivalent of acetic acid becomes free and that the acetate of alumina produced has the form AI2O3+2C4H3O3. A specimen of the pure binacetate prepared by Mr. Crum ex- hibited an equally high osmose as the salt mixed with free acid ob- tained by precipitation which is used below. TABLE XXI1.-Acetate of Aluniina in Osrnometer G of double membrane for five hours. Proportion Rise in Same in Previous Hydrostatic TeE::y-millimeter gramrnes of Diffusatein maceration.redistance. of salt. ciegries. * water. gramme'. Fah. 1 1 i 1 per cent. 3. 232 9-728 days. 2 I 264 11.0U6 1 3'5 65 0.1 195 8208 1 3'5 64 0.1 130 5'472 2 3 66 0-1 0.1 199 146 Ci-68H 6.132 1 >- 3 3 67 87 OSMOTIC FORCE. In the second and third experiments of the Table the solutions were coloured distinctly blue by means of the ordinary sulphate of indigo without interfering much apparently with the osmose. The diffusates when given are as binacetate of alumina and were calculated from the alumina found in the water-jar. In the last three observations of the one-tenth per cent. solution the diffusate of salt is in proportion to the rcplacing water as 1 to 152 131 and 137. In ostnometer F of single membrane acetate of alumina gave a diffusate not exceeding one-third or one-fourth of the diffusate from sulphate of potash in similar circumstances.Thus in three observa- tions of the aluriiinoiis salt the osniose was 356 393 and 397 ins. with the corresponding diffusates of 0.102 0.114 and 0.080 grainme of binacetate of alumina ; while two experiments on sulphate of potash which were intercalated between the second and third of the preceding observations gave diffusates of 0.325 and 0.425gramme of sulphate of potash. The osmose of acetate of alumina does not appear to be sensibly affected by previous experiments made in the same membrane with sulyhuric acid but to fall greatly when an equal proportion of eul- pbate of potash is diffused along with the acetate of alumina.Of the following numbers -4 8 7 237 7 and 18 the first three and thc fifth which are small are the osmose of 0.1 per cent. sulphuric acid alone; the fourth which is large that of 1 per cent. of acetate of alumina and the sixth that of 1 per cent. of acetate of alumina mixed with 1per cent. of sulphate of potash all in the same meni- brane. The diffusate of' the pure acetate of alumina was 0487 gramme which is low for a 1 per cent. solution as compared with the diffusates from the one-tenth per cent. solutions of sulphuric acid which were 0*039,0*04!2, 0.046 and 0.044 gramme of sulphuricacid. The addition of an equal weight of chloride of sodium to the 1 er cent. solution of acetate of alumina lowered the osmose of the Patter salt in osrnometer k' from 397 to 1267 Ins.This is a small amount of interference compared with that exercised by the sulphate of potash in the same membrane. Pure binacetate of alumina was found to be largely decomposed when diffused in open vessels the acetie acid escaping and leaving behind the allotropic soluble alumina of Mr. Crum. This last substance is remarkable for its low diffusibility; but this subject will require fur- ther discussion on a future occasion. Iron. Protosulphate of 1ron.Tfiis salt appeared like sulphate of magnesia to exhibit only the exchange by diffusion of one part of salt for five or six parts of water; the rise of fluid in the osmometer also increasing pretty uniformly with the proportion of salt. Thus in double membrane of good resistance 1 per cent.of this salt (always supposed anhydrous) gave 21 and 30 ms. ; 4 per cent. 60 and 8-1!ms. at a temperature betwcen 61' and 64' Fahr. PROFESSOR GltAHAlU ON Protochloride of Iroa.-This salt separates itself from some other magnesian chlorides and gives rise to a positive chemical osmose which is considerable iu amount. 1’0learn whether this arose from the passage of iron into the higher oxide or not sulphurous acid and hydrosulphuric acid were mixed with the protochloride of iron ;but as will be seen below without lessening the osmose. TABLExxIII.-One per cent. Solutions of several Magnesian Chlorides in Osniornetttr F of double membrane for five hours. Rise in Hgdro-Tempera-Sdt in osmoineter.iilliineter static ture degrees. esistance. Fahr. ~ ~~ ~ ~~~~ 0 rnin. Chloride of magnesium ......... 3 2 59 Chloride of zinc ........... 44t3 2 61 Sanie ............... 54 2 ti2 Chloride of manganese ......... 2-1 1-75 62 Same ............... 34 1-5 ti3 Protochloride of irou .......... 1fi0 1 ti1 Same ............... 19T 1 64 Same ... ........... 4.33 2 ti5 Protochloride of iron +0-1per cent. sulphurous acid ........ ...... 404 4 62 Protochloride of iron sctturatei with SH ... S32 4 ti 4 Pmtochloricle of iron alone ....... 155 4 81 The osmose of protochloride of iron is large but singularly unsteady in amount rising from 160 to 435 ms. and falling again to 155 111s. In another double membrane of rather small resistance (1min.), the osmose of the same salt was only 94,91 and 97 ms.Between the first and second of these experiments the membrane was washed with alcohol and ether but without changing the character of the osmose. In experiments made with this last membrane the 2 per cent. solution of protochloride of iron gave 151 and 157 ms.; and the 5 per cent. solution 189 ms. ;or the osmose did not rise in pro- portion to the quantity of salt in solution Nitrate of Sespuioxide of Iron formed by saturating dilute nitric acid by hydrated sesquioxide of iron gave in single membrane the high osmose of 322 and 359 ms. for 1 per cent. of salt; and 153 followed by 107 ms. for 0.1 per cent. of salt. The acetate of the same oxide give when a deep red colour 207 ms.and when it had become nearly colourlesu from the spontaneous precipitation of a portion of its oxide 194 ms. or sensibly the same osmose. Mangalme.-Sulpbate of manganese appeared to have no decided chemical osmo~e giving in double membrane of moderate resistance (2min.) for 1 per cent. of salt 34 51 and 50 ms. ;for 4 per cent. of salt 53.and 51 ms. and for 10 per cent. of salt 37 and 59 ms. The low osmose of the larger proportions ofthis salt is exceptional and would require confirmation. OSMOTIC FOICE. The chloride of manganese has already been shown to be of low osinose in membrane (24 and 34 ms. Table XXIIT.) ;in albumen the same salt gave 13 and 14 ms. Cobalt.-The chloride of this metal appeared to possess no decided chemical osmose 1 per cent.giving in double membrane 21 and 27 ms. ;0.1 per cent. 20 ad !?3ms. and 1 per cent. agaih 44 ms. NickeL-The sulphate of oxide of nickel resembled that of niagnesia and protoxide of iron. In double membrane 1per cent. gave 12 and 10 nis. ;4 per cent. 38 and 38 ms. j 10 per cent. 72 and 106 ms. The chloride of nickel however appeared to have a tendency to chcniical osmose like the protochloride of iron and gave in double mernbrane 52 89 and 95 nis. Zinc.-None of the salts of this metal can be said to exhibit decided chemical osrnose ;sulphate of zinc giving 34 and 29 ms. nitrate of zinc 18 and 32 ms. and chloride of zinc 48 and 54 ms. all in double meinbrane. Cadmiurn.-The nitrate of cadmium appeared to affect chemical qsmose; the 1per cent.solution of this salt giving in double mem- brane 90 124 and 137 ms. Copper.-Copper appears to possess the capacity for chemical osmose in its salts generally with the exception of the sulpbate. But no sul-phate appears to be remarkable for osmotic activity. The comparative osinose of four salts of copper in the same membrane is given below. TABLE XXIV.-Solutions of 1per cent. of Salts of Copper in Osmometer E of double membrane for five hours. Rim in Salt in solution. millimeter Hydroetatic Pemperature degrees. resistance. Fahr. 0 min. Chloride of copper ........ 351 I (i0 Salphate of copper ........ 45 LO 59 Nitrate of copper ........ 154 10 60 S:tme ............ 204 12 62 Acetate of copper ........ 14P 10 02 Same ............102 10 63 Same ............ 102 10 c,1 The rate of osuiose is general a little deranged on passing from one salt to another in the same membrane and in consequence the second or third experiment is always to be preferred to the first made with the same salt. The preferable numbers for the osmose of the pre- ceding salts would therefore be sulphate of copper 48 ms. acetate 102 iiitrate 204 and chloride 351. The number for the sulphate however is probably too high being raised by the previous chloride. The salts of several of the magnesian metal exhibit a much lower osmose in albumen than in mcmbrane. In an osmometer of the first PROFESSOR GRAHAM ON description nitrate of copper giure only 22 and 27 tns.; acetate of copper 22 and 25 ms.or no inore osmose than is obtained from the corresponding salts of lime and magnesia. Lead-The salts of this metal arc' prahably equally osmotic with those of copper. The nitrate and acetate of lead only were exa-mined. The osmose of these two salts obtained in the same mem- brane was as follows TABLE XXV.-Solutions of 1per cent. of Salts of Lead in Osmo-meter M of double membrane for five hours. m:':i&r l Hydrostatic Temperature Il Salt in solut,ion. degrees. resistance. Fahr. 0 min. Nitrate of lead ......... 174. 2 64 Same ............ 211 2 65 Same .. ......... 1!)7 2 62 Acetate oflead ......... 100 2 64 Same ............ '31 2 61 Proportion Rise in Bame in millimetei grammes of Diffusate in Previous Hydrostatic Tempera-of salt maceration.resistance. ture, pam41es* in solution. degrees. water. Fahr. G per cent. min. 1 91 0 2 61 l-1 127 I I 1 64 1 125 1 1 03 1 157 3 8 ti3 1 157 9 12 63 2 184 1 18 83 2 195 1 12 68 5 209 -1 12 66 5 229 1 12 67 --I-10 2 13 6'3 10 250 10'56 3.288 72 I OSMOTIC FORCE. 91 These experiments lead to the estimation of the osmose of nitrate of lead as follows :-in the 1 per cent. solution an osiiiose of 157 ms. in the 2 per cent. solution 195 ins. in the 5 per cent. solution 229 ins. and in the 10pei..cent. solution 250 ms. This it is to be observed is but a sniall increase for the higher proportions of salt. The diffuaate for the 10 per cent. solution of this salt may be considered of an average proportional amount.The replacing water then exceeds the salt diffused ouly about three and a half times. It is curious that the hydrostatic resistanceof the membrane increases so decidedly as the experiments advance in the osmose of this and several other metallic salts particularly nitrates. It is not to be sup- posed however that this change has any material influence upon the osniose. C-runium.-The nitrate of uranium presented a high degree of osniose. This result scarcely affects the question of the constitution of the metallic oxide present in that salt as a high osmose is exhibited both by the salts containing an oxide of the type R,O, and by a portion at least of the class of protoxides. Viewed as an aluminous salt the nitre of nranium has a basic composition (Ur 0 NO,) a Circumstance which suggested the addition of free nitric acid to that salt in some experiments.The small proportion of one-tenth per cent. of nitric acid will be seen to have a moderate influence and 1per cent. of nitric acid to have an overpowering influence in reducing the extraordinary osmose of this salt. TABLEXXVII.-Solutions of Nitrate of uranium in Osrnometer bl of double membrane for five hours. Rise in Diffuaate Previous Hydro-Tempera-1 1 Proportion of salt in solution. millimeter in macera-static ture degrees. grammes. tion. resistance. Fahr. 0 dys. min. 1 per cent. nitrate of uranium 288 0.078 1 1 60 3 per cent. nitrate of tiraniurn 458 0.102 3 1 61 Sime + 1 per cent.nitric acid 44 0.205 1 1 63 Saaie+ same . . . . . 70 0-136 1 3 66 Same +0-1 per cent.nitricacid 804 0.078 1 3 62 SiiTllC! + same . . . . . 282 0-108 1 3 The inferior osniose of the first observation in the Table arose from the osrnose of the early hours of the esperinient being less than those of the later hours the osmose for the five hours in succession being 36 46 67 77 and 63 ms. This progression combined with the additional circumstance to be observed that the diffusate is below the average in the same experiment suggests the idea of an absorbing or retaining power in the niembrane for the salt which must first be satisfied before the osmose and diffusion can proceed in a regular manner. The diffusate is throughout small like that of an alumiuous salt.PROFESSOR GRAHAM ON In an albumen osmometer the osniose of the same salt was incon-siderable namely 49 and 53 ms.; but that oamose was not further reduced by thc addition of nitric acid. 5'irz.-The protochloride of tin exhibits a high degree of osmose like so many other metallic protochlorides. The I per cent. solution gave in double meinbralie an ostnose of 235 253 289 and 275 ms. The bichloride of tin following immediately in the same membrane gave only 27 ms. But the osmose of the bichloride of this metal is essentially negative even when the salt is made as neutral in corupo-sition as possible. It has been already described. Antimony.-The double tartrate of potash and antimony proved rather remarkable for low osmose.In the first experiment with a double membrane the osmose of the salt in question was 38 ms. but the osmose fell in the second and third repetitions to 12 and 17 ms. The 4 per cent. solution of the same salt gave no more than 23 and 7 ms. Mercury.-The osrnose of the salts of both oxides of this metal is always positive and generally considerable. The osmose appeared to be of least amount in the chloride (corrosive sublimate) to increase in the protonitrate and to assume its greatest magnitude in the pernitrate. Tbe first salt has a stability in solution which the latter two salts do not enjoy. Extraordinary osmose is here therefore associated with facility of decomposition as in so many other instances. The influence of the presence of acids and of chloride of sodium upon the osmose of chloride of mercury was tried in the search for facts which might throw light on the osmotic process.An acid in small proportion appears to favour rather than otherwise the osmose of chloride of mercury. Chloride of sodium on the other hand exerts its usual repressing influence upon the process. TABLE XXVIIL-Solutions of Mercury in Osmometer C of double membrane for five hours. Rise in Previous Hydro-Teinpera-Proportion of salt inRolution. millimeter macera-static ture, 1 1 degrees. tion. resistance. Fahr. 0 days. min. 1 per cent. of chloride of mercury . . 1J 6 4 P 00 Same. ........... 121 3 4 61 0.1 per cent. of cliloride of mercnry . 62 1 4 63 Same. ...........40 1 5 06 1 per cent. cf chloride of mercury +0.1 per cent. of hydrochloric acid ... 163 Same +same ......... 132 Same +o 1 per cent. of nitric acid .. 152 Same +same ......... 132 Same+0.5 per cent. of chloride ofsodium 72 Same +same ......... (i0 OSMOTIC FORCE. Adopting the second experiments as the most trustworthy we have for 1 per cent. of chloride of mcrcury an osmose of 121 ms. and for the same associated with half its weight of chloride of sodium 60 ms. The osmose of chloride of mercury in albumen was very trifling being only 5 and 9 ms. ;chloride of mercury diffused in sensible quantity however through both the albutnen and membrane. Yrotonitrate of mercury gave in double membrane an osmose of 232 346 and 350 ms.; in albumen milch less namely 47 63,and 61 ms.Pernitrate of mercury gave in double membrane 425 and 476 rns. for the 1 per cent,. solution and 296 ms. for the one-tenth per cent. solution results which indicate osniotic power of the highest intensity. The membrane preserved a considerable action after the last experi- ments although macerated in water for a night and imparted thereafter to a salt nearly neutral to osmose (nitrate of silver) a rise of 222 and 166 111s. In albumen pcrnitrate of mercury again was low giving 32 and 54 ms. for 1 per cent of the salt and 34 and 4.6 ms. for the one-tenth per cent. solution. SiZvrr.-It is interesting to observe how this rtietal separates itself frorn mercury and the rnagnesian elements and takes its place with the alkaline metals in the property of osmose as in other chemical characters.Nitrate of silver appeared to possess a moderate positive osmose like a salt of potzsh or soda. For the sake of comparison the silver salt was followed by nitrate of soda in the experiments below. TABLEXX1X.-Solutions in Osmometer G of double membrane for five hours. Rise in Previous Hydro-Tempera-Salt in osmometer. millimeter1macera-static ture, i degrees. tion. Iredance] Fahr. days. min. n 1 per cent. of nitrnte of silver ... 36 z 2 A4 Same. ........... 34 1 2 (ij 0.1 per cent. of nitrate of' silver ... 27 1 2 62 Same. ........... 22 1 2 64 1 per cent. of nitrate of soda .... 7 2 2 61 Same.. .......... 2 1 2 I 64 94 PROFESSOR GRAHAM ON Osmose in membrane of 1 per cent.solutions expressed in millilneter Oxalic acid . . . . . . -148 Chloride of zinc . . . . . . 45 Hydrochloiicacid(O.1percent.) -92 Chloride of nickel . . . . . €9 Terchloride of gold . . . . -54 Nitrate of lead . . . . . . 204 Richloride of tin . . . -46 Nitrate of cadmium . . . . 137 Bichloride of platinum . . -30 Nitrate of'uraninm . . . . . 458 Nitrate of magnesia . . . -22 Nitrate of copper . . . . . 204 Chloride of magnesium . . -2 Chloride of copper . . . . . 351 Chloride of sodium . . . + 12 Protochloride of tin . . . . 219 Chloride of potassium . . . 18 Protochloride ofiron . . . . 435 Nitrate of soda . . . . . 14 Chloride of mercury . . . . 121 Nitrate of silver . . . . . 34 Protonitrate of mercury .. . 350 Sulphttte of potash . . . . 21 to 60 Pernitrate of mercury . . . . 476 Sulpliate of magnesia . . 14 Acetate of sesquioxide of iron . 194 Chloride of calcium . . . 20 Acetate of alumina . . . . 393 Cliloricle of barium . . . . S1 Chloride of aluminum . . . . 640 Chloride of strontium . . . 2G Phosphate ot'soda . . . . . 311 Chloride of cobalt . . . . 26 Carbonate ofpotash . . . . 489 Chloride of manganese . -34 It will be observed tbat acid and alkaline salts are found at opposite ends of the series or while the acids possess negative osmose the alkaline salts exhibit positive osmose in the highest degree. The remark will suggest itself that in osmose water always appears to pass to the alkaline side of the membrane; as water also follows hydrogen and the alkali in the electrical endosmose.The chemical action miiat be different on the substance of the membrane at its inner and outer surfaces to induce osmose; and according to the hypothetical view which accords best with the phenomena the action on the twb sides is not unequal in degree only but also differcnt in kind. It appears as an alkaline action on the albumirioua substance of the membrane at the inner surface and as an acid action on the same substance at the outer surface. The most general empirical conclusion that can be drawn is that the water always accumulates on the alkaline or basic side of the membrane. The analogy does not fail even when the osmometer is charged with an acid solution and the osmose is negative.The stream is then outwards to the water which is a basic body compared with the acid within the membrane. The high positive osmose of the salts of the alumina type is exceedingly remarkable. The property is coinuion to salts of alumina sesquioxide of iron sesquioxide of chromium and the corresponding oxide of uranium. Now the property in these salts is small where thc salt is stable as in the sulphates but becomes great where the affinity between the acid and base is comparatively weak as in the chlorides nitrates and acetates of these bases salts wbich can be shown to be largely decomposed in the experiment by the action of diffusion. Here then as with the prcceding class of osmotic bodies the osmose of the water is towards the basic side of the membrane.But the most curious circumstance with reference to this empirical OSMOTIC FORCE. generalisation is observed in the magnesiau class of salts. The barytic subdivision of t-his class including all the soluble salts of baryta strontia and lime appear to be entirely unosmotic or they oscillate between a small positive and small negative osmose. Such salts are neutral in their reaction and further have no disposition whatevcr to form subsalts. The salts of the earth magnesia itself offer the same characters. But in the salts of certain other oxides of the magnesian group an intensely osmotic character is developed particularly in the salts of copper protoxide of lead and protoxide of tin with the excep- tion of the soluble sulphates of these bases.Now those named are the members of the magnesian class most apt to break up into free acid and a basic salt. Like the aluininous salts therefore they are capable of investing the inner surface of the membrane with basicity the necessary condition of positive osmose Nitrate of uranium does not require. to form a subsalt as it is already constitutionally basic. The osniotic peculiarity of nietaphosphoric acid formerly referred to also harmonises with the same view. Neutral nionobasic salts of the alkaline metals such as the chlorides of potassium and sodium and tlie nitrates of potash soda and silver which possess a strict and unalterable neutrality appear to have little or no true osmotic action. The salts named together with the neutral magnesian sulphates and certain neutral organic substances such as alcohol and sugar give occasion it is true to an increase in the fluid of the osmometer but only to the moderate extent which the exchange of diffusion-volumes might be supposed to produce.The comparative diffusibility of all these substances is well known with the exception unfortunately of that of water itself which I could only deduce by an indirect method in my previous inquiries respecting liquid diffusion. As salts generally appeared to diffuse in water four tinies more rapidly than they did in alcohol the diffusibility of water was then assumed as probably four times greater than that of alcohol and con- sequently five or six times greater than that of sugar or sulphate of wagnesia.Diffusion is thus made to account for the substances last named being replaced in the osrnometer by five or six times their weight of water. This “ diffusion-osmose” appears to follow in its amount the proportion of salt in solution with a certain degree of regularity. The ‘‘ chemical osniose” of substances on the other hand is found of high intensity with small quantities of the substance such as 1per cent. or even 0.1 per cent. and to aupent very slowly with increased proportions of the substance in solution. A small proportion of common salt accompanying carbonate of potash has been seen to possess a singular influence in diminishing the positive osmose of the last-named alkaline salt; while a mixture of small proportions of coninion salt and hydrochloric acid exhibits with the membrane in certain conditions an intense positive osmose which lieither of these siibstances possesses individually.The bibasic salts of potash again such as the sulphate and oxalate PROFESSOR GRAHAM Oh’ OSMOTIC PORCE. although strictly neutral in reaction begin to exhibit a positive osmotic power in consequence it may be supposed of their resolvability into an acid salt and free alkaline base. Tbe sulphate of potash when strictly neutral has in different mem- branes a variable but always moderate positive osmose an osmose which the slightest trace of a strong acid may cause to disappear entirely or even convert into a small negative osmose. On the other hand a minute addition of an alkaline carbonate to the sulphate of potash appears to give that salt a positive osmose of a high order.It was seen that the mixed salts produce much more osniose than the sum of the osrnose of the two salts used apart from each other. It may appear to some that the chemical character which has been assigned to oamose takes away from the physiological interest of the subject in so far as the decomposition of the membrane may appear to be incompatible with vital conditions and osmotic movement con-fined therefore to dead matter. But such apprehensions are it is believed groundless or at all events premature. All parts of living structures are allowed to be in a state of incessant change,-of decom-position and renewal. The decomposition occurring in a living membrane while effecting osmotic propulsion may possibly therefore be of a reparable kind.In other respects chemical osmose appears to be an agency particularly well adapted to take part in the animal ceconomy. It is seen that osmose is peculiarly excited by dilute saline solutions such as the animal jriiccs really are and that thealkaline or acid property which these fluids always possess is another most favour- able condition for their action on membrane. The natural excitaiion of osmose in the substance of the membranes or cell-walls dividing such fluids seems therefore almost inevitable. In osniose there is further a remarkably direct subetitut,ion of one of the great forces of nature by its equivalent in another force-the conversion as it may be said of chemical affinity into rriechanical power.Now what is more wanted in the theory of animal functions than a mechanism for obtaining motive power from chemical decom- position as it occurs in the tissues ? In minute microscopic cells the osmotic movements should attain the highest velocity being entirely depcndent upon extent of surface. May it not be hoped therefore to find in the osmotic injection of fluids the deficient link which intervenes between chemical decomposition and muscular contraction ? The intervention of the osmotic force is also to be looked for in the ascent of the sap of plants. The osmometer of albuminated calico appears to typify the vegetable cell ; the ligneous matter of the latter being the support of a film or septum of albuminous matter in which the active properties of the cell reside.With a vegetable salt like oxalate of potash above and pure watei* below such a septum an upward movement of the lower fluid would neccssarily ensue.