77 General and Physical Chemistry. Magnet-radiometer. By NICOLAE TECLU (J. pr. Chm., 1898, [ ii], 58, 255-260. Compare Abstr., 1893, ii, 401).-The paper contains a detailed description and photograph of the '' magnet-radiometer " designed by the author for use in the diaphonometer previously described by him (Zoc. cit.). The outer portion of the vane of a radiometer is coated with a very thin layer of iron, so that move- ments of the vane can be caused, not only by the action of light rays, but also by the approach of a magnet ; when both forces are applied simultaneously, the position assumed by the vane will be a resultant of the two, and so 3an be applied to the measurement of the intensity of the light falling on the instrument. By FHAN~OIS DUPONT (BUZZ. SOC. China., 1897, [iii], 17, 584)-A much more satisfactory yellow light €or polarimetric observations is obtained when a mixture of sodium chloride and trisodium phosphate, in molecular proportions, is used in place of sodium chloride alone.By DOUGLAS MCINTOSH (J. Physical Chern., 1898, 2, 185--193).-The object of the author in undertaking this research was t o find a convenient standard having an E.M.F. of about 0.5 volt. A cell consisting of zinc, zinc chIoride, lead chloride, and lead, as described by Baille and Fhry, gives good results, and has an E.M.F. of 0.5 at 20' when the specific gravity of the zinc chloride is 1.23. The temperature coefficient is extremely low. A great many cells in which mercuric oxide was used as a depolariser were tried, but none of these were satisfactory, and the use of other oxides as depolarisers gave negative results. Cells of copper, copper sul- phate, mercurous sulphate, and mercury were tried and gave excellent results.The copper sulphate and mercurous sulphate are each taken in the form of a paste. The E.M.F. of this cell decreases with rising temperature, and in the neighbourhood of 1 6 ~ 5 ~ may be calcu- lated by the formula E = 0.3613 + (16.5 - t)0*0006 volt. Cells con- taining Pb, PbCl,, Hg,CI,, Hg were also examined, and gave satisfactory results. The E.M.F. increases with the temperature, and may be calculated approximately between 15' and 21° by the formula B= 0.5382 + ( t - 2l)O~OOOS. Determination of Polarisation. By KARL HEIM (Zeit. Elektl.0- chem., 1898, 4, 527).-In an electrolytic cell of resistance R, with insoluble anode, through which current C is passing with E.M.F. = 3, we have E = p + CR, where p is the polarisation.If a thin sheet of metal be interposed between the electrodes so as to divide the cell completely, without sensibly affecting its resistance, and the current be maintained unchanged, we -have E' = 2p + CR, or p = ,&' - E. In putting the method into practice, the main difficulty is encountered in arranging the cell so that the third electrode may be put in or taken VOL. LXXVI. ii. 6 A. W. C. Yellow Light for the Polarimeter. J, J. S. Normal Elements. H. C.78 ABSTRACTS OF CHEMICAL PAPEKS. out easily, and in such a way that the current shall pass through it, and not round it. A rectangular ebonite cell is provided with platinum electrodes fitting into grooves in the wallg 60 mm.apart. Between these, a third groove, 8 mm. deep and 0.25 mm. wide, receives the third electrode. This depth is sufficient t o prevent undue leakage round the electrode with moderate conductivities and current densities. About half an hour elapses before the polarisation becomes constant. The following are some of the results obtained. A greater depth would be better. Copper sulphate, 16 per cent. a t 14.7-14*95'. Current density ... 0.03 0.06 0.12 0*2 Polarisation ...... 1,591 1.628 1.668 1.695 Silver nitrate, about normal, a t Current density.., 0.015 0.03 0.06 0-12 Polarisation . . . . . . 0.888 0.897 0.903 0.908 0.3 amp./sq. dcm. 1 -71 7 volts. 0-2 0.4 amp./sq. dcm. 0.926 0.935 volt. 15-1 5.5' T.E. Pulverisation of Metal Cathodes During Electrolysis with a Constant Current. By GEORG BREDIG and FXITZ HABER (Bey., 1898, 31,2741-2752. Compare Abstr., 1898, ii, 364).-When a cathode con- sisting of a bright lead plate or wire conveying a current at 24-72 volts is brought into dilute sulphuric acid, a platinum anode being em- ployed, a momentary pulverisation of the lead occurs, and a fine, metallic powder falls through the liquid. This takes place a t isolated spots on the surface of the metal, bright indentations being left with rounded edges. A similar phenomenon takes place in alkaline solutions, but in this case is continuous and much more energetic. The metallic lead thrown down is peculiarly susceptible to chemical change, and can readily be converted into white lead by the simultaneous action of air and carbonic anhydride.The addition of small quantities of a chromate or chromium salt prevents the occurrence of the phenomenon. Mercury, tin, bismuth, thallium, arsenic, antimony, and Rose's metal all show the same phenomenon in alkaline solutions, whereas cadmium, zinc, copper, silver, aluminium, platinum, and palladium do not act in this way. In acid solution, on the other hand, only bismuth and Rose's metal behave in a similar manner to lead. The phenomenon is to be distinguished from the loosening of the surface which occurs with cathodes of platinum, palladium, and lead. I n alkaline solution, it is probably preceded by the formation of an alloy of the metal of the cathode with the alkali metal present, which is then decomposed by the water. This is especially marked in the case of mercury, but no similar action can occur in acid solution.Electrolytic Decomposition of Aqueoufir Solutions. By L. GLASER (Zeit. Elelitrochem., 1898,4, 355, 373, 397, and 424).-The author first repeats the experiments of Smale (Abstr., 1894, ii, 436) on the oxygen- hydrogen gas cell, and confirms his conclusion that the formation of water in this cell takes place in a reversible way a t the E.M.F. of 1-08 volts. He then goes on to determine the E.M.F.'s required to separate the ions contained in various aqueous solutions from their electrical charges. The observations are made by applying any desired A. H.GENERAL AND PHYSICAL CHEMISTRY. 79 E.M.F. from zero upwards to a pair of electrodes immersed in the solution under examination, and noting the current which is thereby caused to pass through the cell.When the E.M.F. is less than that required to produce continuous decomposition, a very small diffusion current is observed. When the decomposition point is reached, the current increases more or less suddenly, so that at each decom- position point a change in the direction of the curve connecting current and E.M.F. is observed. One of the electrodes is made of platinised platinum saturated with atmospheric oxygen, and is very large com- pared with the other ; in this way, its polarisation is rendered practically constant and the changes of direction observed are due to separation of ions at the small electrode. The small electrode being used as cathode, a decided increase of current is found at 1.08 volts with dilute sulphuric acid, and a much less decided change a t the same E.M.F.with solutions of sodium or potassium hydroxide ; the difference is due to the small number of hydrogen ions in the solytions of the bases. I n all cases, a decom- position point is better marked the greater the quantity of the particular ion which is present. When the small electrode was used as anode and the large oxygen electrode as cathode, an exceedingly well marked decomposition point was found a t 0.59 volt with solutions of sodium or potassium hydroxides, and a much less marked decomposition point at 0.6 volt with dilute sulphuric acid. Measured in both cases with reference to the large oxygen electrode, 1-08 volts are therefore required for the continuous separation of hydrogen and 0.59 volt for that of hydroxyl.The sum of these quantities, 1.67 volts, is the frequently observed polarisation in the ordinary electrolysis of dilute aqueous solutions. That visible electrolysis can be produced with 1-08 volts is explained by assuming the separation of 0 ions, the very minute amount of these ions present accounting for the slow course of the decomposition. When a solution of potassium hydroxide is electrolysed, using the small electrode as cathode, two changes of direction are observed in tbe current-E.M.F. curve, The first, at 1.08 volts, corresponds with the separation of the hydrogen ions from their charges, whilst the second corresponds to the separation of potassium ions.The position of the second point varies with the concentration of the potash solu- tions, the following values being found: lON, 1.32 volts; 4N, 1.38 volts; l N , 1.4 volts; +N, 1.45 volts; &N, 1.46 volts. Similar results are obtained with other bases, the values being, 1 normal KOH 1.4 volts 1 ,, NaOH 1.315 ,, 0.0002 ,, Mg(OH), 1.395 ,, 0.02 ,, Ca(OH), 1.33 ,, 0.22 ,, Ba(OH), 1.185 ,, 0.063 ,, Sr(OH), 1.20 ,, The ion separated here is, therefore, hydroxyl. From the latter measurements, it follows that the separation of hydrogen from aqueous solutions is only primary with very small 6-280 ABSTRACTS OF CHEMICAL PAPERS. electromotive forces ; with any ordinary current, the greater part of it is due to secondary action. Thermochemistry of Suberic Acid.By GUSTAVE MASSOL (BUZZ. SOC. Chirn., 1897, [ iii], 17, 745--716).-Suberic acid cryatal- lises in brilliant, white scales melting at 139.5' ; one litre of water at 17" dissolves about 1.8 grams of the acid, the heat of dissolution being - 5.45 Cal. Normal potassium suberate becomes anhydrous at 1 OOO, and dissolves in water with the development of + 0.92 Cal. Potassium hydrogen suberate is only very slightly soluble in cold water ; its heat of dissolution is - 5.36 Cal. at 40'. When a solution of this salt is con- centrated on the water-bath, suberic acid first crystallises out, and then the acid salt, whilst the more soluble normal salt remains in solution, C,H,,O,(solid) + 2KOH(diss.) = C,H,2K,04(diss.) + 17.9 Cal. C,H,,KO,(diss.) + KOH(diss.) = C,H,,K20,(diss.) + I1 -4 Cal.it is calculated that the heats of formation of normal potassium suberate and potassium hydrogen suberate are + 44.76 Cal.and + 25.67 Cal. respectively, all the substances concerned being in the solid state. Thermochemistry of Sebacic Acid. By GUSTAVE MASSOL (Bull. SOC. Chim., 1897, [iii], 17, 746 -747).-Sebacic acid crystal- lises in anhydrous, nacreous scales melting at 129'. One litre of water at 16O dissolves 0.55 gram of the acid, without sensible development of heat. Normal potassium sebate crystallises with one molecule of water, and dissolves in water with the absorption of -1.33 Cal. ; it does not lose water at loo', nor when placed in a vacuum over sulphuric acid, but the anhydrous salt is obtained by heating at 150' in a current of dry hydrogen. Its heat of dissolution is + 1.47 CaI.C,,H,,O,(solid) + 2KOH(diss.) = C,,H1,K,O,(diss.) + 17-68 Cal., it is calculated that the heat of formation of normal potassium sebate is 43.99 Cal., all the substances concerned being in the solid state. Potassium and sodium hydrogen sebates are not sufficiently soluble in water to allow of thermochemical study by the usual methods. T. E. From the heats of neutralisation, N. L, From the heat of neutralisation, N. L. Normal Dibasic Acids of the Oxalic Series. By GUSTAVE MASSOL (Bull. Soc. Chim., 1897, [iii], 17, 747-74S).-The heats of formation of the anhydrous normal potassium salts of some acids of the oxalic series have been found to be as follows : oxalic acid, + 58.97 Cal.; malonic acid, + 48.57 Cal.; succinic acid, + 46.40 Cal.; glutaric acid, + 44.23 Cal.; suberic acid, + 44.76 Cnl. ; sebacic acid, + 43.99 Cal. From these results, it appears that, as the molecular weight of the acid and the distance between the two carboxyl groups increase, the heat of formation of the salt decreases, and ultimately approaches that of two molecules of potassium acetate (43.72 Cal.). The influence of the carboxyl groups on each other decreases rapidly with the intro- duction of intermediary CH,-groups, a fact which is in accordance with the formation of anhydrides from these acids, succinic anhy-GENERAL AND PHYSICAL CHEMISTRY. 81 dride being easily obtained and glutaric anhydride with difficulty, whilst the higher members of the series seem to be incapable of existence.A similar relationship is observed in the production of lactones from acids of the lactic series. Acetaldoxime. By HECTOR. CARVETH (J. Physicul Chem., 1898, 2, 159--167).-The author has repeated Dunstan and Dymond's experiments on the freezing point of acetaldoxime (Trans., 1892, 61, 471 ; 1894, 65, 206), and confirmed them in every detail. All the freezing point phenomena can be accounted for on the assumption of an equilibrium between two modifications in the liquid phase. Although the rate of change of the freezing point of acetaldoxime is a function of the temperature to which the substance is heated, the final equilibrium is independent of the temperature. Heating to 11 4.5' causes the freezing point to drop from 47" t o 1 3 O , and also if the crystals are kept long enough at 20" they will liquefy, and if the liquid is kept for about 10 days and then cooled, the freezing point mill be found to be 13".I n other words, the equilibrium is not displaced by the temperature, and the relative amounts of these two modifications is not a function of the temperature. The liquefaction of the crystals is not accompanied by a measurable change of vapour pressure, and the author regards it as probable that two modifications exist in the vapour. N. L. Sunlight does not produce any visible effect. H. C. Determination of the Speciflc Gravity of Pulverulent Sub- stances. By GUSTAV J. W. BREMER (Rec. Tmv. Chim., 1898, 17, 263--269).-By the following method, more accurate results can be obtained than by using Kopp's volumenometer, and small quantities only of the substance dealt with are necessary; the difficulty of re- moving air bubbles in the ordinary method, using a pyknomefer, is also obviated.A flask (P), having a capacity of from 3-15 c.c., is surrounded by cold water, and is connected to a three-way stop-cock (R) fitted to the top of a manometer tube (a) which is closed below by an ordinary tap, 8, through which it communicates by india- rubber tubing with a pressure tube (C), R enables the flask P to be in connection with the manometer tube alone or with both it and the air simultaneously. The pressure tube is filled with mercury; by raising C, the level of the mercury in a is brought to coincidence, under atmospheric pressure, H, with the upper edge ( p ) of a window in a ring which slides on u near the top.By turning R through 1804 the connection between the flask and the air is broken, and the tube c is then lowered until the level of the mercury in a coincides with the upper edge (q) of the window in a second ring placed near the bottom of a. The difference in level, h, of the mercury in the tubes a and c is measured by a cathetometer. The observations described are then repeated after introducing a weighed amount, w, of the substance taken into the flask P. If h' denote the new difference of level in the tubes a and c, corresponding t o the original h ; H' the atmospheric pressure during the latter part of the experiment, v the volume occupied by the mercury between the levels of the upper edges of the windows p and p, and Q the required82 ABSTRACTS OF CHEMICAL PAPERS.36.40 138-1 35.90 109.8 35-10 75-8 volume of the powder, then x = v . H, as is usual, H=H', 21 -9 46'0 30.20 11.8 34.85 33 -90 32% 32.7 28.10 Acetone. lOs0O 19.91 29.92 40.81 48-67 57-43 60.43 Water. 89.92 80.00 69.67 58.22 48.68 36-64 25.75 Naphthalene. 0-08 0.09 0.4 1 0.97 2.65 5.93 13-82 Teniperature. 65.5" 55.3 45.0 38.0 32.2 28-5 28.2 The effect of a very small quantity of naphthalene on the consolute temperature is very marked, H. C.GENERAL AND PHYSICAL CHEMISTRY, 83 Distribution of Mercuric Chloride between Toluene and Water. By OLIVER W. BROWN (J. Physical CAem., 1598, 2, 51-52). -According to Skinner (Trans., 1892, 61, 342), a fairly constant dis- tribution ratio is obtained when mercuric chloride is added to mixtures of ether and water, Experiments made by the author with toluene and water show that the ratio of the concentrations is not constant in this case, the concentrations in the water phase not increasing quite so rapidly as those in the toluene phase.This would mean, according to the Nernst theory, that there is a slight dissociation in the aqueous solution. H. C. Solubilities of some Sparingly Soluble Liquids in Water. By W. HERZ (Bey., 1898, 31, 2669-2672).-The author has deter- mined the mutual solubility of a number of liquids and water, with the following results. 1000 C.C. of water dissolve 4'20 C.C. of chloroform, forniiiig 1003.9 C.C. ofsolution. carbon bisuhhide, 9 , ), 1'74 2 , ,, 3-41 J , ,, 81-10 Y , ,( 0.82 9 3 ,, 32-84 Y ) ,, 34.81 chloroform dissolve 1-52 carbon bisul- phide dissolve 9'61 light petroleum dissolve 3-35 ether ,, 29.30 benzene ,, 2.11 amylic alcohol dissolve 22-14 aniline ,, 52-22 Lforrniug 1002'08 light petroleum (sp.gr. 0.6646) ,, 1003.41 ether ,, 1071'45 benzene ,, 1000.82 amylic alcohol ,, 1029.92 aniline ,, 1034.81 water ,, 996.2 9 , ,, 1009.61 I , ,, 1006*04 3 , ,, 1032082 1 7 ,, 1001.35 9 5 ,, 1012.82 Y , ,, 1049.55 Indicators. By JOHN WADDELL (J. Physical Chem., 1898, 2, 171-1 84).-According to the dissociation theory, an indicator must be a weak base or a weak acid in which one of the ions has a different colour from that of the undissociated substance, Under these circum- stances, the presence in the solution of a liquid in which the indicator dissociates to a less extent than in water should cause the colour due to the ion to disappear more or less.Nine indicators were, therefore, taken, and tested in presence of alcohol, acetone, ether, benzene, and chloroform. The results obtained were in keeping with the dissocia- tion theory. In alcohol and acetone, the colour of the ion is often perceptible, but this disappears when any one of the other organic solvents is added. It is often possible to predict the acid or basic properties of an indicator from the colour changes on the addition of organic solvents. Methyl-orange and lacmoid act as weak bases ; fluorescein, phenacetolin, and probably corallin are both basic and acid. More satisfactory results were obtained with ammonia and acetic acid than with caustic potash and hydrochloric acid.This the author84 ABSTRACTS OF CHEMICAL PAPERS. regards as due to the dissociation, to some extent, of salts of weak acids and weak bases into the free acid and free base in organic solvents. H. C. By CHARLES A. SOCH (J. Phgsical Chem., 1898, 2, 43-50).-Solubility determinations of the pairs of salts, potassium chloride and potassium nitrate, potassium chloride and sodium chloride, potassium nitrate and sodium chloride, and sodium nitrate and sodium chloride were made at 25O and a t 80' in pure water, and at 25' in 40 per cent. aqueous alcohol. The results are given in the following table, the concentrations being in grams of salt per hundred grams of solvent. Fractional Crystallisation. Aqueous alcohol at 25". Water at 25". KCl ......... 10.06 34.12 ...... 5-29 22.58 1.51 Ratio ......1-90 NaNO, ...... 22.78 43.66 NaCl ........ 10.17 26.58 ....... 2.24 1-64 ...... 13.74 41-14 NaCl ........ 15.78 38.53 Ratio.. ...... 0.87 1.07 NaCl ........ 12.28 29.05 KCI ......... 5.87 17.1 Ratio ........ 2.09 1.70 { KNO, I Water at 80". 40.20 117.5 121.6 0.361 17.62 6.90 39-81 4.1 4 26-5 31.0 168.8 0.855 From the above, it will be seen that the displacement of the equi- librium by the addition of alcohol is in no case as large as the change produced by difference of temperature. A short theoretical treatment of the subject of fractional crystallisation by Bancroft is added. H. C. Absorpt,ion. By JACOSUS M. VAN BEYYELEN (Zeit. army. Chem., 1898, 18: 98--146).-The continuation of the author's research is in accordance with the previous results (Abstr., 1897, ii, 137, and this vol., ii, 12).The elimination of water from the hydrogel, up to a certain point, takes place without the formation of water-free inter- stices, the decrease in volume corresponding with the amount of water evaporated. The greater part of the water evaporates at 15O, with a rapidity little less than that of water itself. As the remaining water evaporates at a steadily increasing vapour pressure, the colloid gradu- ally assumes a solid, glassy condition. The point at which the elimin- ation of water ceases, under a given vapour pressure, varies with the method of formation and age of the colloid, the rapidity of the evaporation, and temperature. In the reabsorption of water by a partially dried colloid, a higher vapour pressure is necessary in order to obtain the same amount of water in the colloid as was present before drying.The absorbing properties of the colloid are decreased by formation in a concentrated silica solution, by prolonged drying, and by time. At a red heat, the absorbing properties are lost. E. C. R.GENERAL AND PHYSICAL CHEMISTRY. 85 General Problem of Chemical Statics. By PIERRE DUHEM (J. Physical Ch,em., 1898, 2, 1-42 and 91--115).--A mathematical paper not suitable for abstracting. H. c. Combination of Gases. By H. H~LIER (Ann. Phys. Chim., 1897, [vii], 10, 521-556).-The author describes the furnace, pyrometer, and gas apparatus employed by him in studying the combination of gaseous mixtures at definite temperatures. Experiments, made on a mixture of hydrogen and oxygen containing the gases in combining proportions, show that a t any given temperature there is a certain limit of combination, and that, after a certain time, continued heating produces no further interaction.This limit is reached in a relatively short time; in the case of oxygen and hydrogen heated to 300', the time required is 17 seconds. The amount of water produced varies with the temperature, at 180' it is only 0.04 per cent., a t 825' i t is 96.1 per cent., and combination takes place explosively at 853' (Abstr., 1896, i, 416). This temperature of explosion is 300' above that indicated by Mallard and Le Chatelier. Van't Hoff defined the tem- perature of explosion as that at which the initial loss of heat due t o conduction, &c., is equal to the heat produced in the same time by the chemical reaction.It may, therefore, be raised considerably by in- creasing the initial loss of heat of the gaseous mixture. Experiments made on the above mixture in the presence of nitrogen, show that the inert gas hinders the combination ; at 491°, the de- crease produced by the addition of 13 volumes of nitrogen is 17.4 per cent. Half the quantity of nitrogen produces aspproximately half this diminution. Excess of oxygen or hydrogen increases the amount of combination, but, volume for volume, excess of oxygen produces greater effect than excess of hydrogen. A mixture of carbonic oxide and oxygen, in combining proportions, begins to react at 195', the amount of combination increases slowly up t o 500°, and more rapidly up to 855O, when it amounts to 65 per cent.The presence of nitrogen diminishes the amount of combination. The inert gas also decreases the velocity of combination; with the normal mixture of carbonic oxide and oxygen at 549O, the limit is reached in 30 seconds; in the presence of l& volumes of nitrogen, the limit is attained only after 70 seconds. An excess of oxygen increases the percentage of combination, ex- cess of carbonic oxide, on the contrary, diminishes the amount of carbonic anhydride produced. The walls of the vessels in which gaseous combination occurs have a marked influence on the results (compare Abstr., 1897, ii, 437, 486, and 548). The combination of hydrogen and oxygen is always complete when the normal mixture is heated for 5 hours in tubes of potash glass, and the water produced is strongly alkaline ; in tubes of lead glass, the combination, carried out under similar conditions, is far less complete, and some of the hydrogen is used up in reducing the lead silicate present.In new silvered tubes, the combination is complete, but on repeating the experiment the amount of water formed, although variable, never indicates complete combination. The presence of water vagour decreases the amount of combination.86 ABSTRACTS OF CREMICAII PAPER3 . This cannot be due to the fact that there is any tendency towards a reverse action. since the effect is well marked a t temperatures far below that a t which steam dissociates . The combination of gases a t any temperature attains a limit.not because the reaction is reversible. but because the presence of the products of combination appears to hinder the completion of the reaction. Report of the Committee of the German Chemical Society on Atomic Weights . By the Members of the Committee : HANS LANDOLT. WILHELM OSTWALD. and KARL SEUBERT (Bey., 1898. 31. 2761-2768).-This report is issued by the committee appointed by the German Chemical Society on December 1. 1897. to consider the question of atomic weights. and to draw up a table of the most pro- bable values of these constants for general use . The members of the committee were unanimous in adopting the two foilowing conclusions . I . The atomic weight of oxygen shall be taken as the standard. and assigned the value 16.000 ; the atomic weights of the other elements to be then calculated from their.directly or indirectly determined. combining proportions with oxygen . I1 . The numbers which may a t present be taken for practical pur- poses to represent the probable atomic weights of the elements are as follows . G . T . M . Aluminium ...... Antimony ......... Argon (2) ......... Arsenic ............ Barium ............ Beryllium ........ Bismuth ............ Boron ............... Bromine ............ Cadmium ......... CEsium ............ Calcium ............ Carbon ............ Cerium ............ Chlorine ............ Chromium ......... Cobalt ............... Copper ............ Erbium (1) ......... Fluorine ............ Gallium ............ Germanium ...... Gold .............. Helium (1) ......... Hydrogen .........Indium ............ Iodine ............... Iridium ............ Iron .................. Lanthanum ...... Lead ............... Lithium ............ Magnesium ......... Manganese ........ Mercury ............ Molybdenum ...... A1 Sb A AS Bil Be Bi B Br Cd cs Ca C Ce c1 Cr co c u Er F Ga Ge All He H In I I r Fe La Pb Li w4 Mn Hg Mo 27.1 120 40 75 137*4 9 '1 208 -5" 11 79.96 112 133 40 12-00 140 35.45 52 '1 59 63-6 166 19 70 72 197'2 4 1-01 114 126.85 193.0 56 -0 138 206'9 7 -03 24-36 55.0 200.3 96 *O Neodymium ( a ) ... Nickel ............... Niobium ............ Nitrogen ............ Osmium ............ Oxygen ............ Palladium ......... Phosphorus ...... Platinum ......... Potassium ......... Praseodymium (2) Rhodium ............ Rubidium ......... Ruthenium .........Samarium ('1) ...... Scandium ......... Selenium ......... Silicon ............ Silver ............... Sodium ............ Strontium ......... Sulphur ............ Tantalum ......... Tellurium ......... Thallium ......... Thorium ............ Tin .................. Titanium ......... Tungsten ......... Uranium ............ Vanadium ......... Ytterbium ......... Yttrium ............ Zinc. ................. Zirconium ......... Nd Ni Nb N os 0 Pd P Pt K Pr Rh Rb Ru Sa s c Se Si Sr S Ta Te T1 Th Sn Ti W iT V Yb Y Zn Zr 2 144 589" 94 14'04 191 16.00 106 31-0 194.8 39-15 140 103.0 85-4 101.7 150 44'1 79.1 28.4 107-93 23-05 87-6 32-06 183 127 204.1 232 118.5" 48'1 184 239-5 51.2 173 89 65'4 90'6INORGANIC CHEM18TR.Y. 87 The numbers in the above table may be regarded as correct t o the last figure given, with the exception of those marked by an asterisk. The atomic weight of nickel is certainly lower than t h a t of cobalt, but the number 58.7 is only correct to k0.2. A like uncertainty holds for bismuth and tin, For hydrogen, the value 1.008 is only certain to 0.001. For practical purposes, the number 1.01 may, therefore, be taken, the error being only about one-fifth per cent. H. C. Gas Generator. By EMIL JAGEI~ (Zeit. cclzgw. Chew., 1898, 961)-The apparatus, of which a drawing is given in the paper, consists essentially of a kind of large wine-glass, but having perfora- tions through the bottom, containing the substance to be acted on and placed at the bottom of a cylindrical glass vessel containing acid. Over it is placed a double bell-jar ; the inner smaller one which plays the part of a diving bell may be lifted up and down by means of a glass rod attached to it. When down, the acid is completely excluded , when up, the acid ascends and acts on the substance. The strength of the gaseous current is regulated by a screw-clamp attached to a piece of india-rubber connected with a side tube belonging to the outer bell- jar. The advantage claimed is that, when out of use, not the slightest evolution of gas takes place, even when the screm-clamp is loosened. L. DE K.