INTERNATIOSAL ATOMIC WEIGHTS. 2577THE Council has ordered Lhe following letter and report to beprinted in the Journal and Proceedings of the Society :WHINFIELD,SALCOMBE,S. DEVON.Seyt. 18tJb, 1914.GENTLEMEN,I have! the honour to forward the Annual Report of tileInternational Committee on Atomic Weights for 1915, which issubmitted for publication in the Society's Transactions and Proceed-ings, as hitherto. Some delay has occurred in presenting it owingto the disturbance of the postal arrangements on the Continent inconsequence of the war, and to the illness of Professor Urbain.The Report deals witlfh all the determinations of atomic weightswhich have been published since the issue of the preceding Report;but, ia accordance with the resolution of the Eighth InternationalCongress of Applied Chemistry, no change in the official table ofatomic weights will be made until after the meeting of the nextCongress.It is recommended, therefore, that the table accompany-ing the Report for 1913 should be reprinted without alteration.I have appended the signatures of Pirofessors Ostwald andUrbain as desired by thein, subject to a qualification by the latterwhich lie proposes t o introduce in the French translation of theReport in connexion with t h e atomic weights of Ytterbium andLutecium.I am, Gentlemen,Your obedient Servant,T. E. THORPE.The Hoiz. Secretarzes,The Chemical Society,Lon don.Annual Itepor t of the International Committee on AtomicWeights, 1915.The Council of the International Association of Chemical Socie-ties, with which the Committee on Atomic Weights is nowaffiliated, recommended, a t its meeting in Septlember, 1913, thatthe annual report of said committee should be published inAugust.The present report, therefore, is submitted in compliancewith that recommendation, although delays due to the diEcu1tie.2578 ANNUAL REPORT OF THE INTERNATIONALof correspondence may sometimw prevent simultaneous publica-tion in all countries.Since the report for 1914 was prepared, a number of new atomic-weight determinations have been published. These may be brieflysummarised as follows :Silver, Sulphur and Chlorine.-Scheuer (Arch. Sci. phys. ?iut.,1913, [iv], 36, 381) dissolved pure silver in sulphuric acid, andcollected and weighed the sulphur dioxide given off.The weighedsulphate was then converted into chloride by heating in a currentof gaseous hydrochloric acid. Three ratios were thus determined,which gave the three desired atomic weights, independent’ of allformer determinations. The results obtained are Ag = 107.884,S=32*067, C1=35*460. The value f o r silver is rather high; theother values agree with those generally accepted.CcrZciuin.-CEchsner de Coninck (BulZ. L4~crd. roy. Belg., 1913,222) has determined the atomic weight of calcium by conversionof the carbonate into the sulphate. His final value is Ca=40.13.Barium.-Also redetermined by CEchsner de Coninck (Re P . yCii.chin). p i r e crppl., 1913, 16, 245). Barium carbonatle was dissolvedin nitric acid, and the carbon dioxide so evolved was weighed.The value found was Ba = 137.36.Copper.-Atomic weight determined by 03clisner de Coninckand Ducelliez (Rec;. g t ~ .chim. pure app!., 1913, 16, 122). Copperwas oxidised by nitric acid, and the oxide was weighed, I n fiveexperiments they found Cu=63.523 t o 63.605; in mean, 63.549.These atomic-weight determinations by CEchsner de Coninck arepublished in the briefest possible way, without’ any of the detailsthat are commonly regarded as essential. How were the substancespurified?Cadmium.-Quinn and Hulett ( J . Physicnl Chenz., 1913, 17,780) have redet’ermined the atomic weight of cadmium by electro-lysis of the chloride and bromide. I n each series the cadmium wascollected and weighed in mercury.From the chloride, withC1= 35.458, Cd = 112.32. From the bromide, with Br = 79-92,Cd = 11 2.26. These values agree well with those previously foundby Perdue and Hulett, and by Laird and Hulett, butl are muchlowelr than the value (Baxter’s) adopted in the table. The causeof the difference is yet t o be satisfactorily explained, but i t mustbe due to a constant error in one or the other of the inethodsemployed. A change in the table would be premature.i1fercury.-Taylor and Hulett ( J . I’kysicccl Chem., 1913, 17,755) prepared mercuric oxide by heating pure mercury in oxygen.Weighed amounts of the oxide were then decomposed by heatingit with metallic iron, and the mercury was collected and weighed.Were the weights reduced t o a vacuumCOMMITTEE ON ATOMIC WEIGHTS, 1915.2579From the data thus obtained, Hg=200*37. This, as in the case ofcadmium, is lower than the recognised value, and its acceptance orrejection must await further evidence.T'ntzadium.-Atomic weight redetermined by Briscoe and Little(P., 1914, 30, 64; T., 1914, 105, 1310) from analyses of theoxychloride, VOC1,. The) mean value found was V=50-950 but50.96 is preferred.Srlet2iLini.-Jannek and Meyer (Zfitsch. nizorg. C'henz., 1913, 83,51) determined the atomic weight, of' selenium by oxidising Se toSeO,.The same constant was deduced by Bruylants and Bytebier(UiiZI. AccxZ. roy. Belg., 1912, 856) from the density of seleniumhydride, SeH,. I n four series of experiments, the weight of alitre) of the gas a t Oo and 760 mm.was found t o be 3.6715 grams.For the weight of a litre of oxygen under the same conditions theyfound 1.4295 grams." By the method of limiting densities, andwith H=l.008, Se=79.18, which is near the value given in thetable.TeZ1ziriicm.-Dennis and Anderson ( J . A Trier. C'liem. Soc., 1914,36, 882) purified tellurium by preparing the hydride, TeH,, fromaluminium telluride, and condensing t h e gas to solid a t thetemperature of liquid air. From the hydride the metal wasobtained by heating t o 500O. Thirty-one conversions of Te thusprepared into TeO, gave in mean Te=127.6. Other determina-tions by a volumetric method gave a lower value, near 127.50.The authors conclude t h a t the higher, hypothetical " dvitellurium "does not exist.Scntzdium.-Lukens ( J .A mer. Chem. Soc., 1913, 35, 1470) pre-pared scandium oxide from Colorado wolfram. By calcination ofthe sulphate to oxide he found Sc=44.59 and 44.77. The materialwas probably not quite pure.Y ttrizcn1.-Meyer and Weinheber (Ber., 1913, 46, 2672), byconversion of yttrium oxidel into sulphate, found Yt = 88-75. Bythe reverse process they found Yt =88*74. Corrected t o a vacuum,this becomes 88.70.Ytterbium and Lutetium.-Atomic weights reinvestigated byAuer von Welsbach (iUor~ntsh., 1913, 34, 1713). For ytterbium(aldebaranium) he found Yb = 173.00. For lutecium (cassiopeium),LU = 175'00.Iridium .-Holzmann (Sit z un p b e r . phys.-m en. Soz. Edangeiz,44, 84) made four reductions of the salt' (NHJ21rCl6 in hydrogen,and found Ir=193*42.This is higher than the accepted value,and not conclusive enough to justify a change.weighs 1.42900 gram?.The mean of ten experiments gave Se= 79.140.* Accoicling to Geiman (Compt. wnd., 1913, 157, Y26), the norinal litreof oxygr2580 ANNUAL REPORT OF THE INTERNATIONALHelium.--Heuse (Ber. Deut. physilial. Ges., 1913, 15, 578), inseven determinations of the density of helium, finds the weight ofa normal litre to be 0.17856 gram. Hence, by the method oflimiting densities, He = 4.002.Neon.-From two determinations of the density of neon, Leduc(Compt. rend., 1914, 158, 864) finds Ne=20.No changes of serious importance seem to be needed in theatomic-weight table. Possibly the values for yttrium, ytterbium,helium, and neon should be changed, but such action may well bedeferred until next year.Some experiments by Richards and Cox( J . Amer. Chem. SOC., 1914, 36, 819) on the purity of lithiumperchlorate also suggest a possible lowering in the atomic weightof silver, namely, from 107.88 to 107.871.(Signed) F. \IT. CLARKE.W. OSTWALD.T. E. THORPE.G. URBAIN.NoTE.-since this report was finished and approved, ProfeaqorUrbain has informed us that, jointly with M. Blumenfeld, he hasre-determined the atomic weight of neoytterbium with great care.The earth was subjected to many fractionations, and each fractionwas stndied magnetically and spectroscopically. The value foundfor the atomic, t-he mean of thirteen determinations, was 173.50.He suspects that the ‘‘ aldebaranium ” studied by Auer von Wels-bach contained an element of lower atomic weight, probablythulium, Urbain’s paper will be published in the near future,perhaps before this repor’c appears. F.W. C.T. E. TCOMMITTEE ON ATOMIC WEIGHTS. 1915 .1915 .Internutionat Atomic Weights .Aluminium ................. A1Antimony ..................... SbArgon ...................... AArsenic ..................... AsBarium ........................ BaBismuth ..................... BiBoron ........................ EBromine .................... BrCadmium ..................... CdCaesiuin ...................... CsCalcium ..................... CaCarbon ........................ CCerium ........................ CeChlorine .....................C1Chromium .................. CrCobalt ....................... CoColumbium ................. CbCopper ........................ CuErbium ..................... ErEuropium ..................... EuFluorine ..................... FGadolinium .................. GdGallium .................... GaGermanium .................. GeGlucinum .................... G1Gold ........................... AuHelium ........................ HeHolmium ..................... HoHydrogen ..................... HIndium ....................... InIodine ........................ IIridium ....................... I rIron ........................... FeKrypton ..................... KrLanthanum ................. LaLead ......................... PbLithium ....................LiLutecium ................... LuManganw .................. Mn................. Dysprosium DY.................. Magnesium MgMercury Hg .....................0 = 16 .27.1120.239.8874.96137-37208.011.079.92112'40132.8140.0712-00140'2535 '4652 '058-9793'563.57162.5167.7152.019'0157.369.972 '59 *1197.23-99163.51 '008114.8126.92193.155-8482.92139.0207.106 '94174'024-3254-93200'62581Molybdenum ............... MoNeon ........................... NeNickel ........................ NiNiton (radium emanation) NtNitrogen ..................... NOsmium ..................... 0 sOxygen ........................ 0Palladium., ................... PdPhosphoriis ..................PPlatinum ..................... 19Potassium ..................... I<Praseodymium ............... PrRadium ........................ KaRhodium .................... BhRubidium .................... RbRu then iu 1 n .................. RuSamarium ................. SaScandium ................... ScSelenium ..................... SeSilicon ........................ SiSodium ........................ NaStrontium .................. SrSulphur ..................... STantalum ................. TaTellurium ..................... TeTerbium ..................... TbThallium .................... TIThorium ..................... ThThulium ..................... 'I'mTin ........................... SnTitanium ..................... TiTungsten ..................... WUranium ..................... UVanadium .................. VXenon ........................ XeYtterbium (Neoytterbium) Y bYttrium ..................... YtZinc ........................... ZnZirconium ................... ZrNeodymium ................. Nd........................ Silver Ag0 = 16 .96. 0144.320.258-68222 '414'01190.916.00106.731 '04195'239'10140.6226 '4102'9101.7150'444-179.228.3107.8823.0087 '6322-0785.45181'5127.5159.2204.0232'4168'5119'048*1184.0238 '551'0130.2172.089.065.3790.6VOL . cv . 8