105 G e n e r a l a n d P h y s i c a l Chemistry. Apparent Variability of the Electro-chemical Equivalent of Copper. By J. VAN" (Ann. Phys. Chem. [el, 44, 214--221).-Gray (Plzil. Mag. [ 5 ] , 22, 389 ; 25, 179), in his researches on the electro- chemical equivalent of copper, found that this magnitude at 12' varied from 0.0003287 with a current density of 20 milliampAres per square centimetre at the cathode, to 0.00032713 with a density of 3.3 mi%- amphres; and at 35" sank so low as 0.0003245. He advances RS a probable explanation of this variability the fact, observed by Gore, that the solution of copper sulphate dissolves up a quantity of copper varying with different conditions. The object of the present investi- gation was to test the validity of this explanation, and to determine the true electro-chemical equivalent.Two copper voltameters with plates of different surface (4 : 1) were placed in the same circuit ; and it was found, for instance, that with a solution of copper sulphate containing 1 per cent. of free sulphuric acid, 0.1903 gram of copper was deposited on the larger cathode, while 0.1960 gram was deposited on the smaller cathode, in the course of three hours. After interruption of the current, the cathodes were allowed to remain three hours longer in the solutions, when i t mas observed that the larger cathode had lost weight to the extent of 9.2 milligrams, and the smaller cathode only 3.2 milli- grams. These weights, added t o the former pair, give 0.1995 gram and 0.1992 gram respectively-results sufficiently close. The author found that when the copper sulphate solution em- ployed contained merely a trace of sulphuric acid (about 5 milligrams per litre), there was no perceptible quantity of copper dissolved in two hours.With such solutions, the electro-chemical equivalents of copper and of silver were compared ; and, taking that of silver as equal to 0.001118, the author gives, as a mean value of 12 concordant ex- periments, the electro-chemical equivalent of copper in cupric salts as equal to 0.0003284. J. W. New Method of Measuring Electromotive Forces and Electrical Resistances. By S. PAGLIBNI (Gnxzettu, 21, 449-454). -A standard wire of known resistance is joined in circuit with the current generator whose electromotive force is to be measured. A branch circuit containing a voltameter is also established, having one terminal fixed to one end of the standard wire and the other fixed to 8 key which slides along the standard wire. The voltameter consists of a glass tube, closed by two taps, containing a 25 per cent.solution of potassium iodide to which has been added a little starch solution. Platinum and copper wires are used for the cathode and anode respectively. The width of the tube is 10 mm. ; the distance between the electrodes 120 mm. The resistance of the standard wires must be so great as to render negligible thc internal resistance of the VOL. LXII. i106 ABSTRACTS OF CHEMIOAL PAPERS. current generator. At the commencement of the determination, the branch circuit is so arranged that the difference of potential at its terminals is insufficient for the electrolysis of the potassium iodide solution: the key ia now moved along the standard wire until it reaches a point at which a violet coloration is observable a t the surface of the platinum wire.The position of the key is then noted, and the electromotive force of the current generator can be calculated in terms of the electromotive force necessary to decompose the potas- sium iodide solution (0.610 volt). Electrical resistances may be measured by employing a current generator of kfiown electromotive force, and inserting the unknown resistance in eit,her the main o r the branch circuit. The author states that this method gives very concordant results. W. J. P. Characteristic Difference between the Substituted Alcohol Radicles directly united with Carbon or with Nitrogen.By C. MATIGNON (c‘ompi. rend., 113, 550--55l).-h the course of a therniochemical study of t h e ureides, the author has arrived at the law, “The substitution of an alcohol radicle directly united with nitrogen increases the heat of combustion more than when the same radicle is directly united with carbon.” The publication of a paper by Stohmann and Langbein (this vol., p. 4), enunciating the same law, rendered necessary the imrnediate production of the author’s r e su 1 t s . Caffeine, theobromine, cholestrophane, and ethylcarbamide were purified and analysed ; their heats of combustion at constant preSsure, together with those of parebanic acid and carbamide, are given below, cal. cal. Caffe’ine(methy1theobromine) C702N4H7Me, 1016.0 Theobromine .............C50,N4H, 845.9) 170.1’ Ethylcarbamide. .......... CON2H3Et, 472.2 320.7 Carbamide ............... CON2H4, Cholestrophane ........... CJ03N,Me,, 538*6 326 Parabanic acid.. .......... C303N2H2, r i 1 he. introduction of a methyl group united with carbon never increases the heat of combustion of the substance by more than 157 cal. ; in the above cases, this number is exceeded by an amount far beyond the limits of experimental error. Ethylcarbamide is con- sidered as derived from urea by two successive methyl substitutions ; takiug 155 cal. as the mean for a substitution of methyl united with carbon, 165.7 cal. is the increase caused by the introduction cf a methyl group combined with nitrogen. The application of this law confirms the suggestion of Grimaux, that pyruvile is a methjl derivative of allantdin, and that it is a true homologue of that substance ; the increase in heat of combustion i n this case is 153 cal.W. T. 151.5 } (= 155 + 165.7). 2 W 6 } (=163 x 2). Expansion of Water. By W. MARRK (Ann. Php. C’hem. [ a ] , 44, 171- 172).--This paper contains a table of the densities of water con-GENERAL AND PHYSICAL CEEMISTRY, 107 taining air for every tenth of a degree from 0" to 31". experimental method will be given in a subsequeni communication. H. C . Details of the Molecular Weights of Liquids as evinced by their Boiling Points. By H. M. VERNOS (Chem. News, 64, 54--58).--The author endeavours to show that from the boiling point of liquids s3me indi- cation as t o the probable value of their molecular weights may be obtained.Hydrogen iodide boils at --So, hydrogen bromide at - 7 3 O , and hydrogen chloride at -loo", from which a boiling point of about -120" might be predicted for hydrogen fluoride. But since hydrogen fluoride actually boils at 19.4", we must assume a more complex molecule for this substance in the liquid state than that represented by the formula HF. This result agrees with Thorpe and Hambly's conclusion that at the boiling point the hydrogen fluoride molecule is probably H,F,. In like manner, comparing the boiling point of water with those of the similar compounds SH2, SeH2, and TeH,, which are gaseous at temperatures far helow O", we should have to assign t p liquid water a molecular weight not smaller than that cor- responding with the formula (H,O)a. The following table illastrates the striking regularity in increase of boiling point which is always observed on the substitution of bromine for chlorine :- Chloride.1 B-P. I-- --- I PC1, ........... -76 -0' POC!, .......... ' 107 '2 AsC13 .......... ~ 134.0 BCI, ............ 18.2 SiCl, ..... ......I 59.6 CHCI,.. ........ I 61.0 CCl, ............ '76 *5 TiC14.. ......... ' 136.1 CH,Cl.. ........ i -22 *O i Bromide. PBr,.. .......... POBr3.. ........ AuBr, .......... BBr, ........... SiBr., ........... CHBr, .......... CBr,. ........... CH3Br.. ........ TiBr, ........... B. p. 175 '0" 195 -0 220.0 90.5 1.54 -0 151 -0 189 '0 4 -5 230 -0 Increase for each atom of Br. ~ ~- 33 *oo 29.3 28.7 24 *1 23 -6 30 *O 28 '1 26 ' 5 23 -5 Other cases are discussed, and the author argues, from a study of the boiling points, that i n all probability all compounds, both organic and inorganic, containing one or more hydroxyl groups, have in the liquid state molecular weights double those expressed by their ordin- arily received formulx?.H. c. Solubility of Gases in Water. By C. BOHR and J. BOCK (Ann. Phys. Chevn. [2], 44, 318--343).-The authors have made fresh determinations of the solubility of oxygen, hydrogen, and nitrogen in water, partly by means of a Bohr's absorptiometer, and parbly by means of two new instruments-a differential absorptiometer and a pumping-out apparatus-which are fully described and figured in the paper. The differential absorptiometer was used for femperatures from 0" to 60"; from 60" to 100" the other apparatus was em- ployed. The mean coefficient of absorption of oxygen in water was found to i 2108 ABSTRACTS OF CHEMIOAL PAPERS.be 0.03497 at 15" ; at 100" it is 0.01679. The agreement with the values obtained by Dittmar and Winckler is good. For nitrogen, the absorption coefficient is 0.01667 at 19", and 0.01046 at 100". The coefficient remains practically constant between 60" and 100'. The authors' numbers agree well with those of Petterson and SondQn, Dittmar, and Hamberg, but diverge considerably from those of Bunsen and of Hiifner. In the case of hydrogen, the author finds that the coefficient of absorption is not independent of the temperature, as Bunsen stated, but falls t o a minimum at about 60", after which it rises until at the boiling point it becomes equal to the coefficient of absorption of oxygen at the same temperature.The numerical values are- a , ~ = 0.0203, a150 = 0.0183, a600 = 0.0144, alm~ = 0.0166. The authors further made two dcteyminations of the solubility of carbonic anhydride, and found a for 37.39' to be 0.5629, and for 100" to be 0-2438. J. W. Nature of Solution. By J. A. WANKLE" and W. JOHNSTONE (Chem. News, 64, 39, 51, and 146 ; compare Abstr., 1891, 1412).- When a solid is dissolved, the volume of the solution is not, as a rule, ,equal to the sum of the volumes of the solid and solvent. The authors have determined the amount of the change for a considerable number of substances which dissolve in water. The alteration, which is usually that of contraction, is expressed in terms of a quantity, which they name the condensate, and obtain by subtracting the mass of solvent displaced by unit mass of dissolved substance from the ratio of the excess of the density of the solution over that of the solvent to the solution-density of the dissolved sub- stance :- .. c = 2 - 21, ____ Density of solution - density of solvent No. of grams of dissolved substance per C.C. of solution ' where i = - - 1 and il = 1 - I Density of dissolved substance The condensate, which, it is stated, may be regarded as the amount of solvent which enters into combination with, or is condensed by, the dissolved substance, appears in several cases to bear a simple molecular ratio to the amount of the latter. Thus, with potassium nitrate, the number is 0.058, whilst the ratio H,O : 3KN0, is 0,059, and with barium hydroxide the number is 0.320, whilst the ratio 3H,O : Ba(OH), is 0.316.I n other cases, however, the agreement is not so close, and the numbers can only be expressed by more complex ratios. With cane sugar, the condensate is zero, whilst with certain am- monium salts it appears to be negative. JN. W. Strong Solutions and the Dissociation Hypothesis. By S. U. PICKERING (Ber., 24, 317-3327) .-The author states that the factQENERAL A:d D PHYSICAL CHEMISTRY. 109 established by him (Abstr., 1891, 972), that weak solutions of sulph- uric acid and other substances contain less, instead of more, acting units than the acid and water separately, caiinot be brought into harmony with the dissociation hypothesis, as Arrhenius considers (Abstr., 1891, 1148), by admitting that complex aggregates of similar molecules exist in pure liquids and strong solutions. After answering some recent criticisms of Arrhenius, he gives a preliminary statement of numerous results obtained in a study of the freezing points of strong solutions.Very weak solutions of electrolytes, as is well known, exhibit an abnormally large molecular depression ; this de- creases as the strength is increased up to a certain point, but after- wards it again increases, and often attains values which are abnorm- ally large in a very high degree. Non-elect'rolytes appear to behave in the opposite manner; in every case investigated, the molecular depression decreases with the strength of the solution, although in a few cases this abnormally small depression is preceded by a com- paratively slight and temporary increase.Although so- called dis- sociation may offer some explanation of the behaviour of very weak solutions, it appears to be incapable of explaining that of strongel- solutions, for here the molecular depression increases, while the amount of dissociation, as measured by the electric conductivity, diminishes. The abnormally high values obtained by Perkin for the magnetic rotation of many salts, &c., in strong solution, and by Gladstone for their refractive indices, is probably due to the same causes as those owing to which these solutions exhibit an abnormally large depression. A table is given in which the rotation values are compared with the amount of dissociation existing, and there appears to be no connection whatever between the two.The Cryoscopy of Cane Sugar Solutions. By S. U. PICKERING (Bey., 24, 332%-3341) .--Numerous determinations, both with very weak solutions, and with solutions up to 64.5 per cent., are quoted, and the results examined in detail, partially by the bent-lath method and partially by the application of parabolas deduced from the experi- mental values. In all the instances where both methods were applied to the same series of results, they have led to precisely the same con- clusions respecting the nature of the figure formed, that is, whether it is a continuous curve or whether it contains changes of curvature. With very weak solutions-0 to 1.2 mols. to lOOH,O, with an actual depression extending up to l*4"-the molecular depression increases from 1.050" to 1.105" at a strength of 0.1 mol., then diminishes to 1.102 at 0.3 mol., and finally increases again till it reaches 1.156" at 1.2 mols.From 0.06 to 1.2 mols. canbe represented by two curves meeting at about 0.6 mol., so as t o give the apparent error of the points very nearly the same value as the known experi- mental error, whereas when the same portion is drawn as one con- tinnous curve the apparent emor is twice the experimental error, and there is such a bad arrangement of error of like signs, that such a drawing could not be accepted as a legitimate representation of the results. Hence the author concludes that a " break " exists at about 0.6 mol. to 100HzO.There appears to be some further irregularity in s. u. P.110 ABSTRAOTS OF OHEMICAL PAPERS. &he region of much weakcr solutioiis, but the position of a break here cannot well be determined. With the freezing points of stronger solutions, the figure is sensibly a straight line as far as about 2.5 mols. ; it then bends downwards as far as 5.5 mols., when i t begins to bend in the opposite direction. The molecular depression for the strongest solution, 9.5 mols., is 1.445, the maximum molecular depression being reached a t 8 mols., where it amounts t o 1.455. The author considem that there is a change of curvature at 2.5 or 2 mols., but not at 5.5 mols., where the inflection of the figure occurs : a representation, either by bent-lath curves or by parabolas, which shows a break at the former point, gives a mean apparent error for the points agreeing very closely with the experimental error, whereas a one-curve representation, which makes no break at this point, gives an apparent error 2.4 times larger than the known experimental error, or taking into account indications of error other than the mean error-such as arrangement of like signs into groups, and the occurrence of errors of improbable ma@- tude-the total apparent error, and, therefore, the improbability, of the one-curve drawing, is estimated by the author to be 100 times greater than that of the two-curve drawing.Representing the figure by three curves, instead of two, produces no appreciable diminu tion in the apparent error of the points. s. u. P.Existence of Acid or Basic Salts of Monobasic Acids in very Dilute Solutions. By D. BERTHELOT (Compt. rend., 113, 641--643).-1f a dilute solution of an alkali is added, in gradually increasing proportion, to an equivalent solution of a monobasic acid, the phenomena can be represented in a very simple manner by means of a curve, the abscissae being the electrical conductivity of the mixture, and the ordinates the proportion of one of the constituents. The curve consists mainly of two right lines (one corresponding with excess of acid, and the other with excess of base), inclined at an acute angle, and connected by a short curved portion, part of which repre- sents the effect of a slight excess of acid, whilst the remainder repre- sents t,he influence of a slight excess of base.A slight escess of base has a greater effect than an equivalent excess of acid, but the effect disappears rapidly as the quantity of acid or base in excess is increased. These results are very distinctly shown by solutions of barium chloride, hydrochloric acid, and barium hydroxide, aud they indicate that acid or basic salts are not completely decomposed by dilution, but exist in minute quantities even in very dilute solutions. C. H. B. Catalytic Influence of Acids on the Velocity of the Reaction between Hydrogen Peroxide and Hydriodic Acid. By G. MAGMANINI (Gaxzetta, 21, 476-490).-l'he author has studied the effect of hydrochloric, nitric, nitro-hydrochloric, sulphuric, hydr- iodic, oxalic, acetic, monochloracetic, and phosphoric acids on the velocity of the reaction between hydrogen peroxide and hydriodic wid, in a similar manner to that employed in his study of the re- action between bromic and hydriodic acids (Abstr., 1891, 144).As in the case of the latter reaction, the velocity of the action is acceler-INORGANIC CHEMISTRY. 111 ated by the addition of acid. When hydrochloric or sulphuric acid is employed, the accelerations are not rigorously proportional to the amount OE acid added, the ratio of the acceleration to the quantity of foreign acid present decreasing slightly, but senei bly, as the amount of acid is increased ; this constitutes a marked difference from the case of bromic and hydriodic acids, in which this ratio increases rapidly with increase of acid. The quantity of iodine set free when nitric acid is used is practically the same as with hydrochloric acid.The accelerating effect of hydriodic acid is very great. Optical Proof of the Existence of Suspended Matter in Flames. By G. G. STOKES (Chenz. Nezus, 64, 167-168 ; compare G. J. Burch, Abstr., 1885, 466).-When a bean1 of sunlight, condensed by a Izns, is passed through a candle-flame, the area of intersection of the double cone of light with the luminous envelope is marked by two brighter patches of light of inappreciable thickness, which exhibit the polarisation of light scattered by fine particles -that is to say, when viewed in a direction perpendicular t o the incident light, it was polarised in a plane passing through the beam and the line of sight. They can be made more conspicuous by viewing the whole through a.cell containing copper ammonium sulphate solu- tion, or through cobalt glass. The same phenomenon is shown by a luminous gas or ether flame, but not by the blue base of a candle flame, or by a Bunsen flame, even when rendered luminous with sodium chloride, or by an alcohol flame, or by an ether flame, j u s t expiring for want of air. The separation of carbon, or carbon associated with hydrogen, thus rendered evident by its polarising effect on light, is due to the actioii on the volatile carbon compounds, in the absence of a sufficient supply of oxygen t o effect complete combustion, of the heat evolved by the more complete combustion at the base of the flame. I n the case of the dying ether flame, the heat is probably distributed over too large a mass of inert gases to effect the decomposition.The thinness of the stratum of glowing carbon is probably due to the combined attack of oxygen on the outside, and carbonic anhydride on the inside (compare Smithells, Proc., 1891, 159). W. J. P. JN. W.105G e n e r a l a n d P h y s i c a l Chemistry.Apparent Variability of the Electro-chemical Equivalent ofCopper. By J. VAN" (Ann. Phys. Chem. [el, 44, 214--221).-Gray(Plzil. Mag. [ 5 ] , 22, 389 ; 25, 179), in his researches on the electro-chemical equivalent of copper, found that this magnitude at 12' variedfrom 0.0003287 with a current density of 20 milliampAres per squarecentimetre at the cathode, to 0.00032713 with a density of 3.3 mi%-amphres; and at 35" sank so low as 0.0003245.He advances RS aprobable explanation of this variability the fact, observed by Gore,that the solution of copper sulphate dissolves up a quantity of coppervarying with different conditions. The object of the present investi-gation was to test the validity of this explanation, and to determinethe true electro-chemical equivalent.Two copper voltameters with plates of different surface (4 : 1)were placed in the same circuit ; and it was found, for instance, thatwith a solution of copper sulphate containing 1 per cent. of freesulphuric acid, 0.1903 gram of copper was deposited on the largercathode, while 0.1960 gram was deposited on the smaller cathode, inthe course of three hours. After interruption of the current, thecathodes were allowed to remain three hours longer in the solutions,when i t mas observed that the larger cathode had lost weight to theextent of 9.2 milligrams, and the smaller cathode only 3.2 milli-grams.These weights, added t o the former pair, give 0.1995 gramand 0.1992 gram respectively-results sufficiently close.The author found that when the copper sulphate solution em-ployed contained merely a trace of sulphuric acid (about 5 milligramsper litre), there was no perceptible quantity of copper dissolved in twohours. With such solutions, the electro-chemical equivalents ofcopper and of silver were compared ; and, taking that of silver as equalto 0.001118, the author gives, as a mean value of 12 concordant ex-periments, the electro-chemical equivalent of copper in cupric saltsas equal to 0.0003284.J. W.New Method of Measuring Electromotive Forces andElectrical Resistances. By S. PAGLIBNI (Gnxzettu, 21, 449-454).-A standard wire of known resistance is joined in circuit with thecurrent generator whose electromotive force is to be measured. Abranch circuit containing a voltameter is also established, having oneterminal fixed to one end of the standard wire and the other fixed to 8key which slides along the standard wire. The voltameter consists ofa glass tube, closed by two taps, containing a 25 per cent. solution ofpotassium iodide to which has been added a little starch solution.Platinum and copper wires are used for the cathode and anoderespectively. The width of the tube is 10 mm. ; the distance betweenthe electrodes 120 mm.The resistance of the standard wires mustbe so great as to render negligible thc internal resistance of theVOL. LXII. 106 ABSTRACTS OF CHEMIOAL PAPERS.current generator. At the commencement of the determination, thebranch circuit is so arranged that the difference of potential at itsterminals is insufficient for the electrolysis of the potassium iodidesolution: the key ia now moved along the standard wire until itreaches a point at which a violet coloration is observable a t thesurface of the platinum wire. The position of the key is then noted,and the electromotive force of the current generator can be calculatedin terms of the electromotive force necessary to decompose the potas-sium iodide solution (0.610 volt).Electrical resistances may be measured by employing a currentgenerator of kfiown electromotive force, and inserting the unknownresistance in eit,her the main o r the branch circuit.The author states that this method gives very concordant results.W.J. P.Characteristic Difference between the Substituted AlcoholRadicles directly united with Carbon or with Nitrogen. ByC. MATIGNON (c‘ompi. rend., 113, 550--55l).-h the course of atherniochemical study of t h e ureides, the author has arrived at thelaw, “The substitution of an alcohol radicle directly united withnitrogen increases the heat of combustion more than when the sameradicle is directly united with carbon.” The publication of a paperby Stohmann and Langbein (this vol., p.4), enunciating the samelaw, rendered necessary the imrnediate production of the author’sr e su 1 t s .Caffeine, theobromine, cholestrophane, and ethylcarbamide werepurified and analysed ; their heats of combustion at constant preSsure,together with those of parebanic acid and carbamide, are given below,cal. cal.Caffe’ine(methy1theobromine) C702N4H7Me, 1016.0Theobromine ............. C50,N4H, 845.9) 170.1’Ethylcarbamide. .......... CON2H3Et, 472.2 320.7Carbamide ............... CON2H4,Cholestrophane ........... CJ03N,Me,, 538*6 326Parabanic acid.. .......... C303N2H2,r i 1 he. introduction of a methyl group united with carbon neverincreases the heat of combustion of the substance by more than157 cal. ; in the above cases, this number is exceeded by an amountfar beyond the limits of experimental error.Ethylcarbamide is con-sidered as derived from urea by two successive methyl substitutions ;takiug 155 cal. as the mean for a substitution of methyl united withcarbon, 165.7 cal. is the increase caused by the introduction cf amethyl group combined with nitrogen.The application of this law confirms the suggestion of Grimaux,that pyruvile is a methjl derivative of allantdin, and that it is a truehomologue of that substance ; the increase in heat of combustion i nthis case is 153 cal. W. T.151.5 } (= 155 + 165.7).2 W 6 } (=163 x 2).Expansion of Water. By W. MARRK (Ann. Php. C’hem. [ a ] , 44,171- 172).--This paper contains a table of the densities of water conGENERAL AND PHYSICAL CEEMISTRY, 107taining air for every tenth of a degree from 0" to 31".experimental method will be given in a subsequeni communication.H. C .Details of theMolecular Weights of Liquids as evinced by their BoilingPoints.By H. M. VERNOS (Chem. News, 64, 54--58).--The authorendeavours to show that from the boiling point of liquids s3me indi-cation as t o the probable value of their molecular weights may beobtained. Hydrogen iodide boils at --So, hydrogen bromide at - 7 3 O ,and hydrogen chloride at -loo", from which a boiling point of about-120" might be predicted for hydrogen fluoride. But since hydrogenfluoride actually boils at 19.4", we must assume a more complexmolecule for this substance in the liquid state than that representedby the formula HF.This result agrees with Thorpe and Hambly'sconclusion that at the boiling point the hydrogen fluoride molecule isprobably H,F,. In like manner, comparing the boiling point ofwater with those of the similar compounds SH2, SeH2, and TeH,,which are gaseous at temperatures far helow O", we should have toassign t p liquid water a molecular weight not smaller than that cor-responding with the formula (H,O)a. The following table illastratesthe striking regularity in increase of boiling point which is alwaysobserved on the substitution of bromine for chlorine :-Chloride. 1 B-P.I-- ---IPC1, ........... -76 -0'POC!, .......... ' 107 '2AsC13 .......... ~ 134.0BCI, ............ 18.2SiCl, ..... ......I 59.6CHCI,.......... I 61.0CCl, ............ '76 *5TiC14.. ......... ' 136.1CH,Cl.. ........ i -22 *OiBromide.PBr,.. ..........POBr3.. ........AuBr, ..........BBr, ...........SiBr., ...........CHBr, ..........CBr,. ...........CH3Br.. ........TiBr, ...........B. p.175 '0"195 -0220.090.51.54 -0151 -0189 '04 -5230 -0Increase for eachatom of Br.~ ~-33 *oo29.328.724 *123 -630 *O28 '126 ' 523 -5Other cases are discussed, and the author argues, from a study ofthe boiling points, that i n all probability all compounds, both organicand inorganic, containing one or more hydroxyl groups, have in theliquid state molecular weights double those expressed by their ordin-arily received formulx?. H. c.Solubility of Gases in Water.By C. BOHR and J. BOCK (Ann.Phys. Chevn. [2], 44, 318--343).-The authors have made freshdeterminations of the solubility of oxygen, hydrogen, and nitrogen inwater, partly by means of a Bohr's absorptiometer, and parbly bymeans of two new instruments-a differential absorptiometer and apumping-out apparatus-which are fully described and figured in thepaper. The differential absorptiometer was used for femperaturesfrom 0" to 60"; from 60" to 100" the other apparatus was em-ployed.The mean coefficient of absorption of oxygen in water was found toi 108 ABSTRACTS OF CHEMIOAL PAPERS.be 0.03497 at 15" ; at 100" it is 0.01679. The agreement with thevalues obtained by Dittmar and Winckler is good. For nitrogen,the absorption coefficient is 0.01667 at 19", and 0.01046 at 100".The coefficient remains practically constant between 60" and 100'.The authors' numbers agree well with those of Petterson and SondQn,Dittmar, and Hamberg, but diverge considerably from those of Bunsenand of Hiifner.In the case of hydrogen, the author finds that the coefficient ofabsorption is not independent of the temperature, as Bunsen stated,but falls t o a minimum at about 60", after which it rises until at theboiling point it becomes equal to the coefficient of absorption ofoxygen at the same temperature.The numerical values are-a , ~ = 0.0203, a150 = 0.0183, a600 = 0.0144, alm~ = 0.0166.The authors further made two dcteyminations of the solubility ofcarbonic anhydride, and found a for 37.39' to be 0.5629, and for 100"to be 0-2438.J. W.Nature of Solution. By J. A. WANKLE" and W. JOHNSTONE(Chem. News, 64, 39, 51, and 146 ; compare Abstr., 1891, 1412).-When a solid is dissolved, the volume of the solution is not, as arule, ,equal to the sum of the volumes of the solid and solvent. Theauthors have determined the amount of the change for a considerablenumber of substances which dissolve in water.The alteration, which is usually that of contraction, is expressedin terms of a quantity, which they name the condensate, and obtainby subtracting the mass of solvent displaced by unit mass of dissolvedsubstance from the ratio of the excess of the density of the solutionover that of the solvent to the solution-density of the dissolved sub-stance :- .. c = 2 - 21,____ Density of solution - density of solventNo. of grams of dissolved substance per C.C. of solution ' where i = - -1and il = 1 - IDensity of dissolved substanceThe condensate, which, it is stated, may be regarded as the amountof solvent which enters into combination with, or is condensed by,the dissolved substance, appears in several cases to bear a simplemolecular ratio to the amount of the latter. Thus, with potassiumnitrate, the number is 0.058, whilst the ratio H,O : 3KN0, is 0,059,and with barium hydroxide the number is 0.320, whilst the ratio3H,O : Ba(OH), is 0.316. I n other cases, however, the agreement isnot so close, and the numbers can only be expressed by more complexratios.With cane sugar, the condensate is zero, whilst with certain am-monium salts it appears to be negative.JN. W.Strong Solutions and the Dissociation Hypothesis. By S. U.PICKERING (Ber., 24, 317-3327) .-The author states that the facQENERAL A:d D PHYSICAL CHEMISTRY. 109established by him (Abstr., 1891, 972), that weak solutions of sulph-uric acid and other substances contain less, instead of more, actingunits than the acid and water separately, caiinot be brought intoharmony with the dissociation hypothesis, as Arrhenius considers(Abstr., 1891, 1148), by admitting that complex aggregates of similarmolecules exist in pure liquids and strong solutions. After answeringsome recent criticisms of Arrhenius, he gives a preliminary statementof numerous results obtained in a study of the freezing points ofstrong solutions.Very weak solutions of electrolytes, as is wellknown, exhibit an abnormally large molecular depression ; this de-creases as the strength is increased up to a certain point, but after-wards it again increases, and often attains values which are abnorm-ally large in a very high degree. Non-elect'rolytes appear to behavein the opposite manner; in every case investigated, the moleculardepression decreases with the strength of the solution, although in afew cases this abnormally small depression is preceded by a com-paratively slight and temporary increase. Although so- called dis-sociation may offer some explanation of the behaviour of very weaksolutions, it appears to be incapable of explaining that of strongel-solutions, for here the molecular depression increases, while theamount of dissociation, as measured by the electric conductivity,diminishes.The abnormally high values obtained by Perkin for themagnetic rotation of many salts, &c., in strong solution, and byGladstone for their refractive indices, is probably due to the samecauses as those owing to which these solutions exhibit an abnormallylarge depression. A table is given in which the rotation valuesare compared with the amount of dissociation existing, and thereappears to be no connection whatever between the two.The Cryoscopy of Cane Sugar Solutions. By S. U. PICKERING(Bey., 24, 332%-3341) .--Numerous determinations, both with veryweak solutions, and with solutions up to 64.5 per cent., are quoted, andthe results examined in detail, partially by the bent-lath method andpartially by the application of parabolas deduced from the experi-mental values. In all the instances where both methods were appliedto the same series of results, they have led to precisely the same con-clusions respecting the nature of the figure formed, that is, whether itis a continuous curve or whether it contains changes of curvature.With very weak solutions-0 to 1.2 mols.to lOOH,O, with anactual depression extending up to l*4"-the molecular depressionincreases from 1.050" to 1.105" at a strength of 0.1 mol., thendiminishes to 1.102 at 0.3 mol., and finally increases again till itreaches 1.156" at 1.2 mols.From 0.06 to 1.2 mols. canbe representedby two curves meeting at about 0.6 mol., so as t o give the apparenterror of the points very nearly the same value as the known experi-mental error, whereas when the same portion is drawn as one con-tinnous curve the apparent emor is twice the experimental error,and there is such a bad arrangement of error of like signs, that sucha drawing could not be accepted as a legitimate representation of theresults. Hence the author concludes that a " break " exists at about0.6 mol. to 100HzO. There appears to be some further irregularity ins. u. P110 ABSTRAOTS OF OHEMICAL PAPERS.&he region of much weakcr solutioiis, but the position of a break herecannot well be determined.With the freezing points of stronger solutions, the figure is sensiblya straight line as far as about 2.5 mols.; it then bends downwards asfar as 5.5 mols., when i t begins to bend in the opposite direction.The molecular depression for the strongest solution, 9.5 mols., is1.445, the maximum molecular depression being reached a t 8 mols.,where it amounts t o 1.455. The author considem that there is achange of curvature at 2.5 or 2 mols., but not at 5.5 mols., where theinflection of the figure occurs : a representation, either by bent-lathcurves or by parabolas, which shows a break at the former point,gives a mean apparent error for the points agreeing very closely withthe experimental error, whereas a one-curve representation, whichmakes no break at this point, gives an apparent error 2.4 times largerthan the known experimental error, or taking into account indicationsof error other than the mean error-such as arrangement of likesigns into groups, and the occurrence of errors of improbable ma@-tude-the total apparent error, and, therefore, the improbability, ofthe one-curve drawing, is estimated by the author to be 100 timesgreater than that of the two-curve drawing.Representing the figureby three curves, instead of two, produces no appreciable diminu tionin the apparent error of the points. s. u. P.Existence of Acid or Basic Salts of Monobasic Acids invery Dilute Solutions. By D. BERTHELOT (Compt. rend., 113,641--643).-1f a dilute solution of an alkali is added, in graduallyincreasing proportion, to an equivalent solution of a monobasic acid,the phenomena can be represented in a very simple manner by meansof a curve, the abscissae being the electrical conductivity of themixture, and the ordinates the proportion of one of the constituents.The curve consists mainly of two right lines (one corresponding withexcess of acid, and the other with excess of base), inclined at an acuteangle, and connected by a short curved portion, part of which repre-sents the effect of a slight excess of acid, whilst the remainder repre-sents t,he influence of a slight excess of base.A slight escess ofbase has a greater effect than an equivalent excess of acid, but theeffect disappears rapidly as the quantity of acid or base in excess isincreased. These results are very distinctly shown by solutions ofbarium chloride, hydrochloric acid, and barium hydroxide, aud theyindicate that acid or basic salts are not completely decomposed bydilution, but exist in minute quantities even in very dilute solutions.C. H.B.Catalytic Influence of Acids on the Velocity of the Reactionbetween Hydrogen Peroxide and Hydriodic Acid. By G.MAGMANINI (Gaxzetta, 21, 476-490).-l'he author has studied theeffect of hydrochloric, nitric, nitro-hydrochloric, sulphuric, hydr-iodic, oxalic, acetic, monochloracetic, and phosphoric acids on thevelocity of the reaction between hydrogen peroxide and hydriodicwid, in a similar manner to that employed in his study of the re-action between bromic and hydriodic acids (Abstr., 1891, 144).Asin the case of the latter reaction, the velocity of the action is accelerINORGANIC CHEMISTRY. 111ated by the addition of acid. When hydrochloric or sulphuric acidis employed, the accelerations are not rigorously proportional to theamount OE acid added, the ratio of the acceleration to the quantity offoreign acid present decreasing slightly, but senei bly, as the amountof acid is increased ; this constitutes a marked difference from thecase of bromic and hydriodic acids, in which this ratio increasesrapidly with increase of acid.The quantity of iodine set free when nitric acid is used is practicallythe same as with hydrochloric acid. The accelerating effect ofhydriodic acid is very great.Optical Proof of the Existence of Suspended Matter inFlames. By G. G. STOKES (Chenz. Nezus, 64, 167-168 ; compareG. J. Burch, Abstr., 1885, 466).-When a bean1 of sunlight,condensed by a Izns, is passed through a candle-flame, the area ofintersection of the double cone of light with the luminous envelopeis marked by two brighter patches of light of inappreciable thickness,which exhibit the polarisation of light scattered by fine particles-that is to say, when viewed in a direction perpendicular t o theincident light, it was polarised in a plane passing through the beamand the line of sight. They can be made more conspicuous by viewingthe whole through a. cell containing copper ammonium sulphate solu-tion, or through cobalt glass. The same phenomenon is shown by aluminous gas or ether flame, but not by the blue base of a candleflame, or by a Bunsen flame, even when rendered luminous withsodium chloride, or by an alcohol flame, or by an ether flame, j u s texpiring for want of air.The separation of carbon, or carbon associated with hydrogen,thus rendered evident by its polarising effect on light, is due to theactioii on the volatile carbon compounds, in the absence of a sufficientsupply of oxygen t o effect complete combustion, of the heat evolvedby the more complete combustion at the base of the flame. I n thecase of the dying ether flame, the heat is probably distributed overtoo large a mass of inert gases to effect the decomposition.The thinness of the stratum of glowing carbon is probably due tothe combined attack of oxygen on the outside, and carbonic anhydrideon the inside (compare Smithells, Proc., 1891, 159).W. J. P.JN. W