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Tous ies autres exemplaires originaux sont filmis en commenpant par la premidre page qui comporte une empreinte d'impression ou d'illustration et en terminant par la dernidre page qui comporte une telle empreinte. Un des symboles suivants apparaftra sur la dernidre image de cheque microfiche, seion le cas: le symbols — ^ signifie "A SUIVRE", le symbols V signifie "FIN ". Les cartes, planches, tableaux, etc., peuvent dtre film^s d des taux de reduction diffdrents. Lorsque le document est trop grand pour dtre reproduit en un seul clich6, il est filmd d partir de I'angle sup6rieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images n^cessaire. Les diagrammes suivants illustrent la m^thode. 1 2 3 32X 1 2 3 4 5 6 N V rji kN ^ I t IILTAMY 0^ /»£^^^ iifi;' ■'» ii .> 1. ■> •• ; ■.<)\ VI I. t On the Calculation of the Conductivity of Aqueous Solutions containing Potassium and Sodium Sulphates. By E. H. ARCHI BALD, B . Sc, ualhousie College, Halifax, N. S. From the Transactions of the Xova Scotian Institute of Science, Vol. /A", Session iSq^-()S, \ I t II I. — On the Calculation of the Conductivity of Aqueous Solutions containing Potassium and Sodium Sul- phates. — Rv E. H. AucHiHALD, B. Sc, DaUioasie College, Halifax, N. S. (Read Xorcmlnr ir.tfi, i-cj:j According to the dissociation theory of eleeti-olysis, hold by Arrhenius and others, the conductivity of a mixture of two solutions of electrolytes, 1 and 2, which have one ion in common, and which contain n^ and a grannne-equivalents per unit of volume, is j^iven by the expression : where v^ and v^ are the volumes of the two solutions mixed, y> the ratio of the volume of the n\ixture to the sum of the volumes of the constituent solutions, /v 1 and /'aja t'ho molecular conducti- vities, at infinite dilution, of the respective electrolytes undei" the conditions in which they exist in the mixture, and ^:.^, n.,, the ionization coefficients of the respective electrolyte'^ in the mixture. The value of p in the above formula may be detormincd by density measurements, before and after mixing ; //^ , and "-^j which for sufficiently dilute mixtures, may be considered to have (291) 2f)2 ON THE CALCrLATlON OF THE CONDUmVITV OF tlic siirne valuos in tlio niixturf us in the simple sr)Iution.s, may 1(0 (l(!tonnim'(l liy conductivity inc'isuronicnts, to throat dilution, of or.cli electrolyte: and v^ and 7?,_, may lie determined l)y analysis. Provided, therefore, vvy Bender, and found it possible to calculate their conductivity vvh( a they contained less than two gramme-molecules i)er litre, within the lindts of experimental error. For more concen- trated mixtures lie found the observed values to be ^'reatcr than the calculated, and the difference to increa.se with the concentra- tion, till at a concentration of four f,n-amme-molocules ])er litre the difference was between 3 and 4 percent. The conductivi- ties of mixtures of Sodium and Hydroffen Chloride solutions were measured and calculate*! by D. Mclntosh.f who found that the conductivity of these mixtures could be calculated, within the limits of experimental error, up to a mean concentration of about one grannne-molecule per litre, and that for a mean con- centration ^'reater than this, the calculated value was f^Tcater than the observed. The measurements, described below, were undertaken with the view of ascertaininif if the conductivity was calculable, in the case of mixtures of solutions of Pota.ssium and Sodium Sulphates, salts of more complex molecular structure than those previously examined. They were conducted in the Physical and Chemical Laboratories of Dalhousie College. The work included purification of the salts, and of water; preparation and analysis of a series of simple solutions, and determination of their conductivity ; plotting- curves, j^iving the relation of concentration of ions to dilution for these simple solutions ; preparation of the mixtures, and measuring and calculating their conductivity. * Transiu-tions N. .^. Inst. .-.iUmuc, ix (IS'.MI), |). 101. t Transiutioiis X. .S. Inst. Scieiuo. ix (IS'.IC), p. 120. Al^UKUL'S SOMJTIOXS. — AHCHIIIAI-D. 291} Pu I'lficatiitii of l/ic Suits. The salts woi'c olitaincd us cliemically pure from Kiinor uikI Aniciul (»F X(>w York. Tliry wcrv can'i'iilly rc-crystalli/cd tlircc times. After lifin^ tliiis treated, no impurities to any exti-nt COul on evaporation. Preparation avd Analysis of Simple Solafioiis. The method adopted was to make up as concentrated a solu- tion as it was desired to measure. This s(»lution was carefully analysed, and from it successive multi])le dilutions were pre- pared by addinnr water, all solutions beinfj prepared at a tempe- rature of 18°C. A volume of Hfty cubic centimetres of these solutions would be introduced into the electn.lytic cell, and successive dilutions prepared from this in the cell itself, by withdrawal of a certain volume, and addition of an ecpial volume of water. As a check upon errors of dilution, after a jiortion had ^one throu^di a numl)er of dilutions, it was taken from the cell and carefully analysed, and, if found necessary, the previous determinations of the concentration were corrected from these results. The concentration of the solutions was determined by gravi- metric analysis, the quantity of salt in solution bein>.,' esti- mated from the amount of IJarium Sulphate precipitated by Barium Chloride, when added in s\\ win', aliout three metres loiif;, wound on a niarhh? drum. The Aire was divided into 1000 parts, and had a resistance of ahout 1.14 ohms. It was calil)rated l»y the method of Strouhal and Harus,* the corrections thus ohtained heinj,' plotteil ai,'ainst len<;th on co-ordi- nate paper, and the correction for an}' point (m the wire taken off this curve. The resistance coils were marked 1, 10, 100, and 1000 ohms. As I used only one coil (tiuit of 1000 oinns), and as it was not necessary to express die conductivities in absolute measure, I did not need to know the relative accuracy of the coils, or the ahsolute value of the one us(;d. Two electrolytic cells were used, one for solutions more con- centrated than 0.1 ecpiivalent f(ra?inne-niolecuIes per litre, the othei" for solutions more dilute. They were of the U-form, shown by Ostwald in his Physico-Chemical Measurements, \y>i^G 226, Hg. 178. The electrodes were of stout platinum foil, not easily bent, circular in form, and about 8.5 cm. in <]iameter. Care was taken to have the electrodes always in as nearly the same posi- tion in the electrolytic cell as possible. No change of resistance could be observed for small diti'erences in position, such as could be detected by the eye, and avoided. The induction coil was small, and had a very rapid vibrator. It was kept in a box stutted with cotton wool, that the noise might not interfere with the determination of the sound mini- mum in the telephone. A Leclanch6 cell was found most convenient for w^orking the coil. With this arrangement the minimum point on the bridge-wire could be determined to within 0.3 of a division. This would allow an error of 0.12 per cent in the determination of the resistance a^. the centre of the bridge, • Wied. Ann., x (1880), p. 320. 20G ON TIIK ('AI.CULATION OK THK < •()Nr)U("TlVn'Y OF and 0.15 per cont at the |)()int fiutliest fnun the contro, usod in my oxpcrinientrt. I'ldtlnizing t/if J'JlecJruiles. Tlio oIoctrodc'R, after l>ein^ wuslicd in Ixjilinf; alkali and acid, weiL' placed in a solution prt'pai'CMJ from a i-ccipc ^ivcn l»y liUmmcr and Kuilliaum, and rcfcrri'd to I'y Koldrausch.* This solution consists of I ])art platinum chloride, OOOS of acetate of lea. 2!)7 tulic, iilHUit :^') cm. lon<,' »iniflrercnce percent. + 1.47 2.000 .a'f7 746.0 .826:^ II .005 .8463 .(5510 707.2 1 m)j + 1.06 .0915 1.998 .o;i5 .79.-)9 .6050 743.4 ! 7:«.4 + 0.67 n 1.667 .588 .8742 .07!»0 (587.7 j (W2.}> + 0.(58 II 1.427 .5:4 .9411 .7440 648.0 (54.5.4 -iO.40 II .9982 .482 l.OSK') .5)060 'm.l 5(55.9 -0.21 .4957 .9975 .37(50 1.473 1.272 4:i8.5 4:^8 +().;« II .0658 .3105 l.8:i7 i.a^ 36116 mL\ -0.21 II .4996 .2740 2.112 1.908 320.9 322.1 -0.37 .4166 .5050 .2572 2.281 2.077 3(J0.6 \m.2 -0.19 .3333 II .2:^) 2.5(«) 2.:»4 270.0 275.5 + 0.18 .2500 II .21 n 2.795 2.576 250.3 249.5 +().:ii II .2525 .LUl 4.121 3.840 180.5 180.9 - 0.22 It .1683 ,i;«2 4.93:^ 4.5.>4 155.7 155.2 +o.:« n .12(52 .1210 .5.4(53 5.024 141.5 141.3 + 0.14 .1000 .1010 .0700 10.02 9.870 81.89 81.JK) -0.01 II .0800 .0631 11.18 11.03 73.81 73.71 + 0.13 II .06734 .0598 12.01 11.86 (59.96 70.05 -0.12 II .05050 .0542 13.3;^ 13.20 63.40 6:149 -0.14 .04000 II .o;m85 22.28 21.95 40.7(5 40.8:5 ().17 .02500 'i .02860 26.96 26.25 :«.45 ;3:5.:36 + 0.26 .01500 II .02570 30.6:^ 30.50 30.05 ;so.i2 -0.2:? 300 ON THK CALCUr.ATION OF THE CONDUCTIVITV OF The concentrations of solutions arc expressed in terms of equivalent