ii. 108 ABSTRACTS OF CHEMICAL PAPERS. Inorganic Chemistry. Model of a Triatomic Hydrogen Molecule. N. BOHR (Medd. K . Vetenskapsakad. robel-lnst. 1919 5 No. 28 1-16).-A theo- retical paper in which it is shown that triatomic hydrogen consists of three nuclei and three electrons. The electrons rotate at equal angular intervals in a common circular orbit whilst the three nuclei are placed on the axis of this orbit. It is shown that H3 cannot. be formed from molecules without the supply of energy from external sources. On the other hand it is shown that in hydrogen gas which is ionised by external agencies molecules of H may be formed by successive processes each of which is accompanied by the production of heat. The Solubility of Sulphur Dioxide in Sulphuric Acid. FRANK DOUGLAS MILES and JOSEPH FENTON (T.1920 117 Some Points of View concerning the Nitrogen Question and Related Problems. L. HAMBURGER (Chem. Weekblad 191 9,16 560-595).-An amplified version of a lecture delivered before the Algemeen Bestuur der Nederlandsche Chemische Vereeniging on July l?th 1918. Electrochemical Reactions of Nitrogen and the accom- panying Spectroscopic Phenomena. L. HAMBURGER (Chem. Weekblad 1918 15 931-942).-A mixture of nitrogen and hydro- gen in stoicheiometrical proportions under a pressure of 12 mm. af mercury was passed through a quartz capillary tube and subjected to a direct-current discharge of 1 2 amperes per square cm. A yield of 109 mg. of ammonia per kilowatt-hour was obtained. Reduction of the current density and simultaneous increase of the time of exposure to the discharge gave mu& smaller yields.The conditions for a high yield of ammonia thus correspond with those necessary for the formatioc of activated atomic nitrogen and hydrogen. The discharge through mixtures of nitrogen with hydrogen oxygen and carbon monoxide was examined spectroscopically. I n every case evidence af the disruption of the molecules and formation of new compounds such as cyanogen was obtained. EUGBNE WOURTZEL (Compt. rend. 1919 189 1397-1400).-As a result of measurements at temperatures between Oo and 86.5O it is shown that the variation of the dissociation constant with the temperature is given by log El T = 8.9908 - 2810.5 / T and calculated from this the heat of polymerisation is 12,850 cal. exact t o 0.5%.Luminescence and Ionisation in the Oxidation of Phosphorous Oxide. HERMAN RINDE (AT& Kern. Min. Geol. 1917-18 7 No. 7 1-21).-A mixture of oxygen and carbon J. F. S. 59-61). W. S. M. W. S. M. The Dissociation Constant of Nitrogen Peroxide. W. G.INORGANIC CHEMISTRY. ii. 109 dioxide dried by means of sulphuric acid calcium chloride and phosphoric oxide and warmed to a suitable temperature is passed through two absorption bulbs containing phosphorous oxide with the vapour of which it becomes saturated. No luminescence takes place with the dried gas but when the mixture is led over the surface of water contained in a tMt-tube luminescence appears. The absorption bulbs and test-tube containing water were immersed in a thermostat a t constant temperature and the total intensity of the luminescence was measured photographically by means of a Martens’ photometer. There is no luminescence in pure carbon dioxide but the addition of oxygen causes the phenomenon to appear and its intensity is greatest in mixtures containing 5% of oxygen.With increase in the percentage of oxygen the intensity decreases and attains an approximately constant value between 50% and 100% oxygen (com- pare Scharff A. 1908 ii 373). When a tube 3.75 metres long is inserted between the absorption bulbs and the tesbtube the intensity of the luminescence is about the same for mixtures containing a low percentage (about 5%) of oxygen but it rapidly diminishes with increasing oxygen content to a lower value than before the tube w~ts inserted. At the same time t.he tube becomes covered with a deposit of phosphoric oxide.These results indicate that the phos- phorous oxide is oxidised without luminescence by the dry oxygen and that the diminished luminescence with mixtures containing high percentages of oxygen is due t o the fact that the gas coming into contlact with the water-vapour contains much less phosphorous oxide. According to Scharff (Zoc. cit.) the merest trace of water-vapour is sufficient to cause luminescence but €he author finds that when the vapour pressure of the water-vapour is diminished as for example by using concentrated sulphuric acid instead of water the luminescence becomes very feeble. As with all gas reactions the width of the test-tube containing the water affects the intensity of the luminescence.The wider the test-tube the less the luminescence. The author suqgwts that> in dry oxygen phosphorous oxide is directly oxidised t o phosphoric oxide but that in moist oxygen an intermediate compound X is formed according to the equation Ionisation does not occur in a gas free from oxygen but contain- ing phosphorous oxide. In the presence of oxygen ionisation takes place and the author has measured the saturation current (compare Harms A. 1904 ii 331; Bloch A. 1905 ii 72). The ionisation is not a photoelectric effect as shown by measurement of the satura- tion current with different electrodes but is caused by the oxidation of an unknown intermediate product formed from phosphorous oxide and water vapour. Th3 mobility of the ions is small corn- pared with that of ordinary gaseous ions but of the same order as that obtained for the ions formed in the oxidation of phosphorus (ccmpare Harms and Bloch loc.cit.) and it is very probabIe that the isns are produced by the same reaction in both cases. T. S. P. P,O t; RpO + 0 + X + HSPO,.ii. 110 ABSTRACTS OF CHEMICAL PAPERS. Some Chemical Characters of Ancient Charcoals. T. C CANTRILL (Archaeol. CambrensG 1919 365-392) .-Although the pieces of charcoal or charred wood found during archzeological exca- vations are more readily attacked or dissolved by such reagents as nitric acid and potassium chlorate and hypochlorite solution thus differing from modern well-burnt charcoal the author considers that the solubility etc. of some of the ancient charcoals is simply due to their incomplete carbonisation and that there is doubt that they were produced by the agency of fire.The situations in which certain of the charcoals are found negatives the opinion that the blaokening of wood was due t o the action of peaty soil. Artificial Production of Diamond. SIR CHARLES A LGERNON PARSONS (Phil. Trams. 1919 A 220 67-107).-Bakerian lecture. It is shown from experiments that all the hydrocarbons chlorides of carbon and oxides of carbon deposit amorphous carbon or graphite on a carbon rod electrically heated at any pressure up to 4400 atms. and in a few cases up to 6000 atms. A t 15,000 atms. carbon and graphite electrically heated are either transformed into soft graphite or are first vaporised and condensed as such. The experiment of compressing a mixture of acetylene and oxygen and the production of a temperature in excess of that required to vaporise carbon accompanied by a momentary pressure of 15,000 atms.shows that the failure to convert graphite into diamond is not due to lack of temperature. The experiment of firing a high-velocity steel bullet with cupped nose through vaporising carbon into a hole in a block of steel raises the pressure moment>arily to 300,000 atms. and the temperature probably 1000° but the fact that only a few minute crystals resembling diamond were produced (probably from the iron) leaves a doubt as t o whether the duration of the pressure was sufficient to start a recogn'lsable transformation of graphite to diamond. A repetition of many of the experiments in which diamond has been claimed to be formed has given negative results except where iron has played a part.A list of the experiments tried together with conditions and results is given in an appendix to the paper. In repeating Moissan's experiments i t is shown that when a crucible of molten iron is subjected to pressure more than three times as great as can be produced by these contractile forces the yield of diamond is not increased; on the other hand if the ocoluded gases are imprisoned then the yield of diamond is about the same as when the crucible is plunged into water whilst if the conditions are such as to allow a free passage of the gases through the skin of the ingot the yield is a t once reduced even though the bulk pressure on the ingot is the same.Experiments in vacuum from 75 mm. to X-ray vacuum show generally that as the pressure is decreased the yield of diamond is diminished and below 2 mm. no diamond could be detected. The greatest percentage of diamond ocourred when the atmosphere round the crucible consisted of 95% carbon monoxide 1% Kydrogen 2% hydrocarbons 2% nitrogen. The weight of diamond is about 1/20,000 of the weight of the iron. It appears that the formation of diamond in rapidly cooling iron takes W. P. S.INORGANIC CHEMISTRY. ii. 111 place when i t is solid or in a plastic condition or even a t a lower temperature. The rapid Fitting of a diamond in highly carburised iron just above its melting point is so pronounced that the largest diamond hitherto produced artificially would be destroyed in a few seconds if the iron matrix were molten.The experiments indicate that the bulk pressure on the metal dues not play a part in the formation of diamonds but that the previous heat treatment the impurities in the iron and the condition of the gases within the metal are the important factors. The iron in the most successful experiment has a concentration of diamond 270 times as great as the blue ground in the South African mines. Production of Carbon Monoxide in the Flames of Gases. ANDRB KLING and DANIEL FLORENTIN (Compt. rend. 1919 169 1404-1406).-A number of gases the carbon monoxide content of which varied from 0% to 60% were burnt a t differing types of burners in a large chamber and the carbon monoxide in the air waa estimated at the end of one hour. The results indicate that the pro- duction of carbon monoxide is due principally to the sudden cooling of the flame.For a given type of burner the amount of carbon monoxide present in the gas to be burnt is without influence on the amount present in the products of combustion. The Auer burner produced comparatively large amounts of carbon monoxide this production being due apparently to the presence of the incandescentt mantle. The hourly production of carbon monoxide with certain common types of burners is sufficiently high to warrant further efforts to improve them. Atomic Structure oi Metals in Solid Solution. A. L. FEILD (Chem. and M e t . Eng. 1919 21 566-570).-The reason for the difference in physical properties of solid solution alloys and their components has been investigated.It is concluded that the alloys retain in the solid state the same atomic structure as in the liquid state the metals being in the amorphous form. Such a solid solution is analogous to a supercooled liquid with the same electrical resistance and temperaturecoefficient of resistance as in the molten state. Experiments with alloys of nickel and chromium and of gold and silver confirm this theory. It does not apply to eutectic alloys. The hardness of alloys is also ascribed to an amorphous state. J. F. S. W. G. W. J. W. Transition of Dry Ammonium Chloride. ALEXANDER SMITH HERBERT EASTLACK and GEORGE SCATCHARD ( J . Amer. Chern. SOL 1919 41 1961-1959).-Time-temperature curves both heating and cooling have been made for absolutely dry ammon- ium chloride with the object of ascertaining whether the dry mate- rial changes into a second crystalline form a t 184*5* as does the undried material.It is shown that ammonium chloride which has been dried for forty-five days at 155+165O or for three years with phosphoric oxide in a high vacuum undergoes exactly the same transition a t 184.5' as the undried salt. In the thermal measure- 4**ii. 112 ABSTRACTS OF CHEMICAL PAPERS. ment of transition points in a high vacuum confusion may result from the greater thermal effects of distillation. Wegscheider’s explanations of the anomalous vapour density of dried ammonium chloride by a failure to undergo transition in the absence of water are untenable in the light of these resu1t.s (A. 1918 ii 298). J. F.S. Lithium Silicate. K. ALB. VEBTERBERG (Nedd. K. Vetens- kapsakad. Nobel-Inst . 1919 5 No. 30 1-9) .-Amorphous silicic acid which has been dried a t looo dissolves slowly in a fairly con- centrated (approx. 2N) solution of lithium hydroxide a t the ordin- ary temperature giving finally a solution containing 3.4 mols. of SiO to 1 mol. of L&O. Thus lithium behaves similarly to potassium and sodium in giving soluble silicates containing a large excess of acid over the base (oompare A. 1915 ii 344; also Jordis and Ranter A 1903 ii 475 542 595; Jordis 1908 ii 291; Ordway 1908 ii 37). In warm lithium hydroxide solution however silicic acid is almost insoluble the acid being transformed into a practi- cally insoluble lithium silicate. Lithium metasilicate occurs in two modifications the one easily soluble and the other almost insoluble.The latter which has the formula Li2Si03,H20 is obtained as a white granular precipitate when a fairly concentrated solution of sodium metasilicate is mixed with the equivalent quantity of lithium chloride lithium hydroxide added in approximately normal concentration and the solution heated for a short time a t 80-90°. It can also be obtained by dissolving silicic acid which has been dried at a temperature not higher than looo in twice the theoretical amount of 2N-lithium hydroxide solution a t the ordinary temperature and then heating the solution for a short time a t 80°. T. S. P. A New Physicochemical Method of Analysis of Precipi- tates. Application to the Study of the Calcium Phosphates.PIERRE JOLIBOIS (Compt. rend. 1919 169 1161-1163).-The two solutions from which the precipitate is obtained are very rapidly mixed by means of the apparatus previously described (this vol. ii 107) and the precipitate is collected and analysed and the super- natant liquid is also analysed when equilibrium has been reached. Applying this method to the study of mixtures of solutions of calcium hydroxide and phosphoric acid in varying proportions the author has prepared and characterised a new calcium phosphate having the composition 2Ca0,P20,,3Ca0,P20,,10H20. This phos- phate ocmrs in a crystalline form and in the presence of excess of phosphoric acid is slowly converted into the dicalcium phosphate. W. G. Research on Magnesia Alba by Joseph Black Petrus Driessen and Others.W. P. JORISSEN (Chem. Wsekblad 1919 16 1579-1589).-The author gives a retrospect of the researches of Joseph Black on magnesia alba which led to his discovery of carbon dioxide (“.fixed air ”). The niet.hods of preparation ofINORGANIC CHEMISTRY ii. 113 magnesia alba described in the literature 011 the subject are varia- tions of the original experiments of Black Driessen and other investigators of the eighteenth century. W. J. W. Zincates of Sodium. Equilibria in the System Na,O-ZnO-H,O. F. GOUDRIAAN (Proc. K. Akad. Wetensch. Amsterdam 1919 22 179-189).-The solubility isotherm in the system N+O-ZnO-H,O has been completely determined a t 30' by dissolving zinc oxide in solutions of sodium hydroxide of various concentrations and determining the solubility.The following sub- stances appear as stable solid phases zinc oxide sodium zincate N+0,Zn0,4H20 and the monohydrate of sodium hydroxide. Sodium zincate forms very strongly incongruent solutions ; in solu- tions containing 1 part of sodium hydroxide to 2 parts of water it is decomposed with separation of zinc oxide. Amorphous gelatinous zinc hydroxide is to be regarded as a phase of a varying water con- tent; it is impossible to remove all adsorbed ions from it and i t is metastable as regards zinc hydroxide. I n special circumstances zinc hydroxide may be obtained as a crystalline phase of the constant composition Zn(OH),. This crystallised hydroxide is metastable at 30° with respect of zinc oxide. J. F. S. Reguline Lead Peroxide. WILH. PALMAER (Medd.K. Vetenskapsakad. r'Vobel-Inst. 1919 5 No. 31 1-15).-Compact lead dioxide has been prepared by the electrolysis of lead nitrate solution. The product is greyish-black in colour and has a pro- nounced crystalline appearance and contains no impurities ; it has a hardness 5-6 and D 9.360. I n all respects it is similar to the mineral plattnerite. The specific resistance a t 1 8 O is 0*000845 ohm and the specific conductivity 1180 ohm-1. The temperature- coefficient of the conductivity is 1/8% per degree. J. F. s. Aluminium Spontaneously Oxidisable in the Air. E. KOHN-ABREST (Compt. rend. 1919 169 1393-1395) .-Attention is drawn to the fact that when aluminium is distilled in a vacuum a t llOOo the globules of aluminium remaining undistilled a t the end of sixteen to twenty hours when exposed to the air a t the ordinary temperature undergo spontaneous oxidation giving a yellowish-grey powder which is a mixture of the oxide and the finely divided metal.This aluminium only contained 0.4% of iron and 0.5% of silicon. W. G . Chemical Method for the Determination of the Strength of Sparingly Soluble Inorganic Bases. K. A. VESTERBERG (Arkiv. Kern. Min. Geol. 1917 6 No. 11 1-20).-The deter- mination of the hydrolysis of salts of sparingly soluble inorganic bases by electrometric methods and methods depending on the inversion of sucrose or the hydrolysis of esters has given very vary- ing results according to the methods used (compare Denham T. 1908 93 41; Lund&n A. 19Oe ii 164). Farmer's method (T. 4*"-2ii. 114 ABSTRACTS OF CHEMICAL PAPERS.1901 79 863) for the determination of hydrolysis does not give correct values owing to the disturbance of the hydrolytic equil- ibrium by the partial extraction of the one product of hydrolysis. I n the case of cobalt acetate for example too little acetic acid is extracted. The1 author makes use of Farmer's method but modifies and corrects it as follows. The solution is extracted with twice its volume of ether; t-he same et'hereal solution is again used to extract half its volume of a fresh solution of cobalt acetate. This process is repeated until the concentration of the ether phase becomes constant with respect to aceltic acid showing that i t is in equil- ibrium with hydrolysed cobalt acetate solution in which base and acid are present in equivalent proportions.Ths percentage hydro- lysis can then be readily calculated. Usually the concentration of the ether phase becomes constant after three extractions. Corrections have1 to be made for the increase in volume of the aqueous phase by solution of et.her and the ether and salts used have to be specially purified. I f the acetate is difficult to obtain pure accurate results can be obtained by using a solution of the sulphate or nitrate to which an equivalent- quantity of sodium acetate has been added. The determinations were carried out a t 1P the distribution coefficient of acetic acid between ether and water being taken as 2.1. The results obtained for percentage hydrolysis were as follows AT/2-cobalt acetate 0.19; N/5 0.165 ; NI2-nickel acetate 0.435; N / 5 0.38.It follows that cobalt hydroxide is a stronger base than nickel hydroxide and this agrees with the stabilities of their sulphates. The fact that the hydrolysis is greater in the stronger solutions may be due to the greater salting-out effect of the acetate on the acetic acid. The hydrolysis of lanthanum acetate in NIEi-solution was 0.315% and in N/lO-solution 0.286% the value 0.31% being taken as correct for both solutions the differences being within the error of experi- ment. Lanthanum acetate was found to have 1$H,O of crystal- ligation the solubility a t 180 being 20.43 grams of the anhydrous salt in 100 grams of water; it loses &H,O a t looo. T. S. P. A New Complex Form of Chromic Sulphate. A. RECOURA (Compt. rend. 1919 169 1163-1166).-When a N/2-solution of chromic sulphate is allowed to remain until equilibrium is reached in so far as the formation of the green sulphate is concerned and then evaporated to saturation point in a vacuum on the addition of an excess of alcohol a lilac-grey precipitate is formed.If this precipitate is immediately collected and washed with a litt.le ether it is found to contain 18H,O and to have the whole of its "SO precipitable by barium chloride. It changes however spon- taneously and rapidly when exposed to the air and at the end of the day contains only 16H20 and gives no precipitate with barium chloride. If left in a desiccator. its wakr content finally drops to 12R,O. The constitution of this new complex sulphate has not yet been determined. W. G.INORGANIC CHEMISTRY.ii. 115 Method of Obtaining and Optical Study of Crystals of Sodium Chromate Tetrahydrate. LUCIEN DELHAYE (BUZZ. SOC. franc. min. 1918 41 80-92) .-Deliquescent monoclinic crystals 5 mm. in length can be obtained by allowing a solution of sodium chromate saturated a t 50° to cool to about 27O filtering and keep- ing for several days with occasional shaking. The refractive indices optic axial angle dispersion etc. have been measured for light of various wave-lengths. CHEMICAL ABSTRACTS. Chemistry of Quinquevalent Tungsten. OSCAR OSON COLLENBERG (Ark& Kem. Min. Geol. 1918 7 No. 5 1-35).- Solutions of tungstic acid and alkali tungstates in oxalic acid or alkali oxalate solutions are readily reduced t o quinquevalent tungsten derivatives. From the solution of tungstic acid in oxaIic acid pure solid reduction products could not be isolated but if the solution is saturated with hydrogen chloride and then treated with a solut.ion of rubidium chloride in concentrated hvdrochloric acid the compound diruhidium pentnchlorotungstite Rb,WOCl crystallises out in very good yield.When a solution of an alkali tungstate in oxalic acid solution containing a slight excess of alkali oxalate is reduced with tinfoil the colour passes through dark blue and becomes green yellowish-green and finally red. On cooling the highly concentrated solution oxalic acid alkali oxalate and tin oxalate separate. The tin is removed by hydrogen sulphide from the solution and on adding alcohol a dark reddish-brown powder separates. On dissolving the powder in water and addinp; an excess of alkali iodide or bromide it is obtained pure.I n this way the ordo-tunnstites of wodium. potassium and ammonium have been prepared. whilst the sodium salt is similar except that it contains 12H,O. The oxalo-tungstites are suitable substances for the preparation of other auinquevalent tungsten derivatives. They dissolve readily in hydrochloric acid to produce deep blue solutions from which the oxy-chlorides of quinquevalent. tungsten may be separated. Thev are soluble in potassium thiocyanate solution producing deep red- coloured solutions ; they dissolve in concentrated hydrofluoric acid solution producing violet solutions. On boiling with potassium cyanide yellow solutions are obtained from which double cyanides of the type M4W(CN)8 may be isolated.The alkali oxalo-tungstites may be converted into chloro-tungstites by the following methods (a) by treating the hydrochloric acid solution of an alkali (K or NH,). oxaletungstite with hydrogen chloride ( b ) by adding chlorides (rubidium cesium aniline tetraethglammonium and tetrapropylammonium) to t,he hydrochloric acid solution of an oxaletungstite and ( c ) by adding either pyridinium chloride or quinolinium chloride t o a solution of ammonium chloro-tungstite in concentrated hydrochloric acid. By these methods derivatives The potassium salt has the formula 3K90,2 W,0,,4Cz0,,9HoO of the types (i) M?WOCl,(M =NH,. Rb Cs C,H,*NH3) (ii) M,WOCl,,zH,O(M =K),ii. 116 ABSTRACTS OF CHEMICAL PAPERS. (iii) MWOCl,(M = C,H,NH C,H,NH) and (iv) MWOCl,,H,O(M = [C2H5],N [C,H,],N) have been prepared.All the derivatives obtained have been shown by titration with potassium perman- ganate or by titration with iodine and arsenious acid to contain the tungsten in the quinquevalent condition. The chloro-tungstites are finely crystalline powders; they are quite stable in dry air but a t 60-70* are oxidised turning blue and eventually quite white. They are hydrolysed by water and a reddish-brown hydroxide is produced. I n the case of the less soluble compounds for example the esium salt C%WOCl the hydrolysis is not. complete. The chloro-tungstites are soluble in concentrated hydrochloric acid and in the case of the metal derivatives the solubility decreases with increasing atomic weight; t-hey are insoluble in most organic solvents excent in the case of the rubidium and czsium derivatives which are soluble in absolute methyl and ethyl alcohol.The solu- bility in methyl alcohol is very much greater than in ethyl alcohol. Oxidising agents convert the chloro-tungstites into sexavalent tungsten derivatives. A vigorous reaction takes dace on treatment with potassium cyanide with the production of double cyanides of the type M,W(CN),. The compounds of the type (iii) and (iv) are regarded as derivatives of metatungstous acid 02W*OH -+ Cl4W*OR whilst those of types (i) and (ii) are regarded as deriv- atives of orthotungstous acid W(OR,) + (HO)2W(OH)3 e HFd>WCl,. For the special description and preparation of the individual chloro-tungstites the original should be consulted.J. F. S. Decomposition of Stannous Chloride by Water and by Potassium Hydroxide Solutions. C. M. CARSON (J. A ~ T . Chem. Soc. 1919 41 1969-1977).-Making use of the principles of the phase rule the author has investiqated the action of water and potassium hydroxide on stannous chloride. The1 experimental results show that the compound 2SnC12,7Sn(OH) is the most. basic of all the basic stannous chlorides. A slightly variable crystalline material of approximately the formula 3SnC1,,5Sn0,3H20 is the precipitate commonly formed bv the action of boiling potassium hydroxide on an excess of stannous chloride and there is no corn- pound of intermediate composition. Whether any basic compound lies between 3SnC1,,5Sn0,3H20 and the normal salt was not deter- mined.The precipitates usually formed by t-he action of water on stannous chloride contain such a large proportion of stannic com- pound that the analyses are of no value in ascertaining the composi tion of the basic stannous chlorides. The Peroxides of Bismuth. RICHARD ROBERT LE GEYT WORSLEY and PHILIP WILFRED ROBERTSON (T. 1920 117 A. GUTBIER and 0. MAISCH (Ber. 1919 52 [ B ] 2275-2280).-The experi- J. F. S. 63-67). Behaviour of Hydrogen towards Rhodium.MINERALOQICAL CHEMISTRY. ii. 117 ments were performed in the same manner as with palladium iridium and platinum (A. 1913 ii 608; 1919 ii 367 368). The results may be summarised in the following manner. The deep black modification rhodium-black is able to absorb far more hydrogen than any other form. The maxima of hydrogen absorp- tion amounted to 180 volumes a t 190° for the greyish-black form 165 volumes a t 40° for the slightly greyish-black variety and 206 volumes at Oo for the deep black modification. (The varieties are obtained in the order given by the reduction of sodium rhodium chloride by hydrazine in faintly acid neutral and ammoniacal solu- tion respectively; the purest preparations dried in a vacuum over phosphoric oxide contained about 3% of water and 0.3% of oxygen.) The absorption of hydrogen by rhodium is much less than by palladium and corresponds with that observed with platinum. Spongy rhodium like spongy platinum only absorbs small amounts of hydrogen. H. W.