FIPU’DLAY AND HOWELL : THE 1NFLUEKCE OF COLLOIDS, ETC. 291XXXI1.-The Influence of Colloids and Fine Suspensionson the Solubility o f Gases in Water. Part I??Solubility of Niti-ous Oxide at Pressures Lowerthan Atmospheric.By ALEXANDER FINDLAY and OWEN RHYS HOWELL (UniversityStudent in Chemistry).IN previous communications have been given the values of thesolubility of carbon dioxide in water in presence of colloids atpremures varying from about 250 up to about 1400 mm. ofmercury; as also the solubility of nitrous oxide under pressuresvarying from 750 to 1400 mm. (T., 1910, 97, 536; 1912, 101,1459; 1913, 103, 636). I n the present communication we completethe series by giving the valaes of the solubility of nitrous oxideunder pressures lower Lhan atmospheric.I n order to be able tocombine these results more satisfactorily with those previouslyobtained by Findlay and Creighton (T., 1910, 97, 536), thesolubility determinations were extended up to pressures of about1000 mm.The apparatus employed and the general method of workingwere as described by Findlay and Williams (T., 1913, 103, 636).The nitrous oxide was prepared by heating carefully purifiedammonium nitrate, as described by Findlay and CreightonSolzc bil it y Bet ermina tions.(a) Water.(loc. c i t . ) .The following values were obtained for the solubility of thenitrous oxide :TABLE I.Solubility of Nitrous Oxide in V a t e r .Pressure ............. 282.5 396.1 562.9 664-5 789.3 1027.5Solubility ........... .0.585 0.585 0.584 0.585 0.585 0.585Pressure .............272.8 393.2 548.6 652.4 751.0 1021-7Solubility ..; ......... 0.585 0.585 0.585 0.585 0.585 0.586As mean value of the solubility, therefore, we obtain 0.585, anumber somewhat lower than that obtained by Geffcken (Zeitsch.physikal. Chem., 1904, 49, 298), namely, 0.5992, o r that obtainedby Findlay and Creighton (Zoc. cit.), 0.592292 FINDLAY AND HOWELL: INFLUENCE OF COLLOIDS, ETC.,(b) Ferric IXycEroxide Solution.The ferric hydroxide solution was prepared by the method ofA. A. Noyes (J. Arner. C?zJem. SOC., 1905, 37, 94). It was freedfrom salts by dialysis, and rendered air-free by boiling underdiminished pressure. The values of the solubility are contained intable I1 (compare Fig. 1).FIG. 1.0.6000,5900'5800.5700.560@ 0'550Y2 0'5400'5300.52005100 '5000'490106250 350 450 550 650 750 850 950 105Presszsre in mm.Hg.Nitrous oxide and ferric hydToxidc (- - -1.Nitrozu oxide and dextrin (-).TABLE 11.Solubility of Nztrous Oxide in Ferric Hydroxide Solutions.Concentration: 0.43 gram of Fe(OH), in 100 C.C. of solution.Density= 1.001.Pressure ............. 291-2 409-1 574.7 648.5 767.5 1029-8Solubility ............ 0-594 0,594 0.591 0.589 0.583 0.580Pressure ............. 279-4 402-1 561.4 668.9 785.9 1043.7Solubility ............ 0.594 0-592 0.591 0-588 0.553 0.580Concentration: 0.92 gram of Fe(OH), in 100 C.C. of solution.Density= 1.003.Pressure ............. 287.0 425.0 571.6 681.4 787-9 1054.6Solubility ............ 0.589 0.587 0.584 0.582 0.578 0.576Pressure .............283.0 408.5 564.6 646.5 776.0 1026-7Solubility ............ 0.590 0.586 0.584 0.582 0.579 0.57ON THE SOLUBILlTY OF GASES IN WATER. P,QRT IV. 293TABLE I1 (conthued).Concentration: 3.82 gram of Fe(OH)3 in 100 C.C. of solution.Density= 1.027.Pressure ............. 256.1 372.9 543.7 633-6 764-8 1014.3Solubility ............ 0-583 0-581 0.580 0.577 0.572 0.568Pressure ............. 247-9 363-3 524.4 646.4 747.9 987-3Solubility ............ 0-583 0.582 0.579 0.576 0.573 0.568(c) Dextm’a.The concentrationof the solutions WSLS determined by evaporating to dryness, andweighing the residue after drying in the steam-oven. The solu-bility values are given in table I11 (compare Fig.1).Kahlbaum’s purest dextrin was employed.TABLE 111.Solubility of Nitrous Oxide i7z Dextrin Solutions.Density= 1.019.Pressure ............. 281.5 407.1 565.1 673.1 819.1 1004-6Solubility ............ 0.557 0.550 0442 0.542 0.547 0.554Concentration: 6.82 grams of dextrin in 100 C.C. of solution.Concentration: 6.70 grams of dextrin in 100 C.C. of solution.Density= 1.019.Pressure ............. 284.3 407-8 560.7 664.7 773.1 980.6Solubility ............ 0.555 0.550 0.544 0.544 0-546 0.554Concentration: 12.41 grams of dextrin in 100 C.C. of solution.Density = 1.037.Pressure ............. 283.8 407.7 574.8 660.5 785.7 985.0Solubility ............ 0.537 0.532 0.526 0.527 0.526 0.534Concentration: 12.50 grams of dextrin in 100 C.C.of solution.Density= 1-037.Pressure ............. 281-6 416.3 577.1 671.7 774.0 971.4Solubility ............ 0.535 0.530 0.526 0.526 0.524 0.532Concentration: 13.24 grams of dextrin in 100 C.C. of solution.Density = 1.060.Pressure ............. 293.0 421.5 598.7 695.5 799-3 997.5Solubility ............ 0.515 0.510 0.504 0.501 0.500 0.50294 FINDLAY AND HOWELL: INFLUENCE OF COLLOIDS, ETC.,TABLE I11 (continued).Concentration: 19.31 grams of dextrin in 100 C.C. of solution.Density = 1.060.Pressure ............. 288.2 413.4 569.2 646.0 777.0 996.2Solubility ............ 0.516 0.510 0.504 0-502 0.500 0.506(d) Starch.Kahlbaum’s pure soluble starch employed for the determina-The solubility values are given in table IV (compare tions.Fig.2).FIG. 2.Nitrous oxide and egg albumen (- - -).Nitrous oxide and starch (-).TABLE IV.Solubility of Nitrous Oxide in. Stmch Solutiom.Concentration: 6-76 grams of starch in 100 C.C. of solution.Density = 1.023.Pressure ............. 285-2 415-0 566.7 657.5 770.3 1054.0Solubility ............ 0.565 0.563 0.560 0.560 0.553 0.550Concentration: 6-70 grams of starch in 100 C.C. of solution.Density = 1.023.Pressure ............. 263.6 370.5 524-7 646.6 750.6 997.5Solubility ............ 0.566 0.563 0.561 0.558 0-554 0.549Concentration: 9.58 grams of starch in 100 C.C. of solution.Density = 1.030.Pressure ............. 267.6 373.7 504.8 627.7 747.1 1024.0Solubility ............ 0.554 0.551 0.549 0.546 0.541 0.53ON THE SOLUBILITY OF GASES IN WATER.PART IV. 295TABLE IV (continued).Density = 1.029.Pressure ............. 290.5 416.5 576.8 659-0 775.8 1003.6Solubility ............ 0.551 0-550 0.548 0.543 0.540 0.537Concentration: 9-40 grams of starch In 100 C.C. of solution.Concentration: 13.62 grams of starch in 100 C.C. of solution.Density = 1.039.Pressure ............. 284-3 418.4 614.8 703.2 843-0Solubility ............ 0.541 0.537 0.535 0.532 0-528Concentration: 13.60 grams of starch in 100 C.C. of solution.Density = 1.039.Pressure ............. 263.8 378.6 496.9 624.0 756.1 973-5Solubility ............ 0-541 0-539 0.536 0-534 0.530 0.525(e) Gelatin.I n these experiments French gelatin, free from salts, wasemployed.TABLE V.Solubility of fiitroits Oxide in Solutions of Gelatin (seealso Fig.3).Density = 1.000.Pressure ............. 256.5 372-2 530.5 623.9 755.0 1009-6Solubility ............ 0.582 0.581 0.577 0.575 0.579 0.581Pressure ............. 260.9 379.4 542.5 646.5 763.4 1032-1Solubility ............ 0-581 0.582 0.575 0.577 0.579 0-579Concentration: 1-45 grams of gelatin in 100 C.C. of solution.Concentration: 3.12 grams of gelatin in 100 C.C. of solution.Density = 1.004.Pressure ............. 251-5 367.3 530.3 632.4 750.7 1000.0Solubility ............ 0.577 0.576 0.568 0.569 0.572 0.576Concentration: 3.16 grams of gelatin in 100 C.C. of solution.Density = 1.004.Pressure ............. 287.8 414.5 569.2 668.5 796.3 1054-0Solubility ............ 0.577 0.574 0.570 0.570 0.572 0.576Concentration: 6.10 grams of gelatin in 100 C.C.of solution.Density = 1.008.Pressure ............. 257.7 381.0 546.4 637-4 762-9 1029.9Solubility ............ 0.556 0.556 0.548 0-546 0.550 0.68296 FINDLAY AND HOWELL INFLUENCE OF COLLOIDS, ETC.,TABLE V (continued).Density = 1.008.Concentration: 6-14 grams of gelatin in 100 C.C. of solution.Pressure ............. 259.0 380.6 546.5 639-8 759.6Solubility ............ 0.556 0.655 0.548 0.646 0.650( f ) Egg-a1 b umen.Commercial egg-albumsn was employed. This was treated withwater, and the solution, after filtration, submitted to dialysis.FIQ. 3.Nilrous oxide and silicic acid (- - -).JVitrous oxide and gelatin (-).TABLE VI.Solubility of Nitrous Oxide in Solutions of Egg-albumen (seealso Fig.2).Concentration: 0.38 gram of egg-albumen in 100 C.C. of solution.Density = 0.998.Pressure ............. 248.7 361.3 530.7 633-7 755.7 996.2Pressure ............. 262-1 370-5 537-3 634.5 733.5 915.0Solubility ............ 0.572 0.573 0.573 0-572 0.571 0-568SOh1bility ............ 0.572 0.573 0.573 0.572 0.570 0.571Concentration: 0.62 gram of egg-albumen in 100 C.C. of solution.Density = 1.000.Pressure ............. 254.1 380.0 453-5 644.5 762.5 1020.5Solubility ............ 0.568 0.569 0.568 0-567 0.565 0.57ON THE SOLURILI'I'Y OF GASES IN WATER. PART IV. 297(9) Silicic a c i d .Pure silica was dissolved in potassium hydroxide solution, andthe, clear solution poured into excess of hydrochloric acid. Themixture was then submitted to dialysis until free from chloride.The concentration is expressed in terms of SiO,TABLE VII.Solubility of Nitrows Oxide in Solutions of Silicic Acid (seealso Fig.3).Concentration: 1.62 grams of SiO, in 100 C.C. of solution.Density = 1.000.Pressure ............. 254.9 369-1 536.8 664.0 764.8 1007.1Pressure ............. 255.1 370.4 537.6 676.0 765.4 1025.6Solubility ............ 0.594 0.591 0.589 0-588 0.588 0.591Solubility ............ 0.590 0.587 0.589 0-589 0.588 0.592Concentration: 3-50 grams of SiO, in 100 C.C. of solution.Density = 1.004.Pressure ............. 250-2 375.2 546.5 687.5 758.7 1033.7Solubility ............ 0.600 0-595 0.594 0-593 0.594 0.598Pressure ............. 250.1 376.6 557.2 653.6 757.6 1004.0Solubility ............0.596 0.595 0.593 0.594 0.595 0.598(h) Suspemions of Silica and of Charcoal.For these experiments finely-powdered silica and animal charcoalwere employed. The charcoal was boiled with water, and then,after being dried a t looo, was heated in a vacuum almost toredness.The solubilities obtained with suspensions of silica did not differappreciably from those in pure water. With charcoal the followingvalues were obtained (see also Fig. 4) :Concentration: 3.0 grams of charcoal in 100 C.C. of water.Pressure ............. 252.6 366.8 527.7 626.6 749-8 989.5Solubility ............ 0.580 0.586 0.587 0.588 0.588 0-609Pressure ............. 255.3 374.3 545.3 639.0 760-3 1001.3Solubility ............ 0.583 0.581 0.586 0.591 0.588 0.610Discussion of Results.The solubility values which have now been obtained fit inexceedingly well with the values obtained at higher pressures byFindlay and Ckeighton (Zoc.cit.) if one allows for the slightdifference in the value for the solubility in pure water. Since theVOL. cv. 298 FINDLAY AND HOWELL: THE INFLUENCE OF COLLOIDS, ETC.solubility values recorded here were carried out up to pressuresof about 1000 mm. of mercury, whilst the pressures under whichthe experiments of Findlay and Creighton were carried out variedfrom about 750 mm. upwards, the two sets of solubility curvesoverlap over a considerable range; and we have found that overthis range the two sets of curves are parallel with one another inthe case of any particular solution.The two sets of experiments,therefore, mutually confirm each other.Although it is hoped to discuss more generally at a later timethe general question of the solubility curves obtained in the caseof carbon dioxide and nitrous oxide, i t may be mentioned herethat an examination of the solubility curves for nitrous oxide asobtained by the present authors and, previously, by Findlay andCkeighton, reveals a remarkable uniformity in general behaviour.FIG. 4.0'6200.610d2 0.600 z2 0-5900-58@0.570&Is250 350 450 550 650 750 850 950 1050Pressure in mna. Hg.Nitroils oxide and charcoal (- - -).X i t ~ o u s oxide and silica (--.).On considering the solubility curve for pressures varying fromabout 250 to 1400 Him. of mercury, i t is found that in every casethe curve exhibits a minimum, which is rather shallow indeed inthe case of solutiona of silicic acid, but is very well marked inmost of the other cases, for example, in the citse of solutions ofgelatin, dextrin, and ferric hydroxide. Even in the case ofsolutions of starch we have found that the solubility of nitrousoxide passes through a quite distinct minimum value, although it isremarkable that no such behaviour was met with in the solubilityof carbon dioxide in starch solutions (Findlay and Williams,loc. cit.). Although we have no reason to doubt the accuracy ofany of the determinations, this somewhat exceptional behaviour,as it. appears, of carbon dioxide in starch solutions makes it neces-sary for us to study more fully that particular case.THE Er)wAm DAVIES CHEMICAL LABORA-I OKIEY,UNIVEEW~Y OF WALES,ABERYS'I'WPTII