92 In organic C h e m i s t r g. Decomposition of Hydrogen Peroxide. By WALTH~RE SPRING (Zeit. anoyg. Chem., 1895,10, 161--176).-When a 38 per cent. soln- tion of hydrogen peroxide is heated at 60' in a platinum dish which has been previously polished, no decomposition takes place; at a higher temperature small bubbles of gas are formed. When, how- ever, the inside of the dish is scratched with a needle, small gas bubbles are formed at the scratch, even at the ordinary tempera- ture, and on raising the temperature a brisk evolution of gas takes place. A 70 per cent. solution of hydrogen peroxide contained in a glass flask is only slowly decomposed when a current of air from a wide tube is passed through i t ; if, however, a capillary tube is used, brisk decomposition takes place.The author has examined the decomposition of hydrogen peroxide when mixed with various solutions. Five C.C. of a 36 per cent, hydrogen peroxide solution is mixed with 5 grams of each solution, and allowed to remain for a given time at 65' in a thermostat, and the remaining hydrogen peroxide titrated in acid solution with per- manganate ; the solutions employed contain 1 gram mol. of dry salt to 38.5 gram mols. of water. Rydrochloric and nitric acids decom- pose the peroxide quickly, but sulphuric and phosphoric acids have a preservative action. The decomposing action of salt solutions is more energetic the feebler the base they contain and the more readily the acid they contain is oxidised or reduced by hydrogen peroxide ; thus, lithium and sodium snlphates produce only a slight decomposition, magnesium chloride about double, and aluminium chloride about treble this decomposition, whilst sodium and potas- sium carbonates entirely decompose hydrogen peroxide.This decom- position is due to t'he acid function which hydrogen peroxide evinces towards some salts. If a solution of hydrogen peroxide is gradu- ally added to a solution of an alkali carbonate, pure oxygen ifi evolved ; if, however, the carbonate is added to an excess of hydro- gen peroxide, it is completely converted into alkali dioxide and carbonic anhydride. The ratio of the concentration of two solutions of st salt is not equal to the ratio of their decomposing action on hydrogen peroxide. E. C. R. Action of Hydrogen Peroxide on Ammoniacal Copper Compounds : Preparation of Oxygen.By DIOSCORIDE VITALI (L' Orosi, 1895, 1-5) .-When hydrogen peroxide is added to ammoniaca.1 copper sulphate, a brisk effervescence takes place in the cold, and oxygen is evolved in abundance, the copper salt remaining unchanged; and as an indefinite amount of the peroxide can be decomposed by means of the same portion of the metallic compound, pure oxygen may be very conveniently prepared by allowing the ordinary aqueous peroxide (3-4 per cent.) to flow steadily from a tap-funnel into a saturated solution of ammoniacal copper sulphatelNORGANIC CHEMISTRY. 9 3 (20-30 c.c.) contained in a fairly capacious Woulff's bottle. The gas is dried and purified from ammonia by means of sulphuric acid. The mechanism of the action appears to be analogous to that of the decomposition of potassium chlorate in presence of manganese dioxide ; the cupric compound reacts with the peroxide, yielding a cuprous salt and free oxygen, and the cnprous compound is then re- oxidised by another portion of the peroxide.The same action occurs to a limited extent with copper hydroxide alone, and to a varying extent with ammoniacal solutions of other metallic salts, but in no case is it continuous as with copper; mer- curic oxide and mercurocs nitrate, for instance, are visibly reduced, and the action ceases as soon 3,s tho reduction is complete. The method is not applicable to the estimation of hydrogen per- oxide in aqueous solution, as the whole of the oxygen is not evolved, part being employed in oxidising ammonia to nitrous and nitric acids, which may be detected in the solution at the end of the operation.JN. W. Formation of Ozone. By OTTO BRUNCK (Zeit. anorg. Ciiem., 1895, 10, 222-247 ; see also Abstr., 1893: ii, 454)-The anthor has already proved that the intense odour of the oxygen prepared from a mixture of potassium chlorate and manganese dioxide is chiefly due to the presence of ozone. A fui*ther examination of the gas shows that only a very minute trace of chlorine is evolved, equal in Rmount to that evolved in the decomposition of pure potassium chlorate alone. If the mixture is heated at 400" and above, at which temperature the dioxide commences to decompose, then more chlorine is evolved. It has already been shown that oxygen is ozonised when passed over heated manganese dioxide or certain other metallic oxides, and this action has been further examined.The ozone is estimated as follows : the gas is passed through a neutral solution of potassium iodide, which is then acidified with dilute sulphuric acid, and titrated with N/100 sodium thiosulphate solution. The action of ozone on an acidified potassium iodide solution takes place according to the equation 0 3 + 2KI = 21 + K,O + 0,; when, however, ozonised oxygen is passed through a neutral solution of potassium iodide, athe action takes place according to the equations O3 + 2KI = 21 + K2O + 0, and 61 + 3K20 = KI03 + 5KI. The second reac- tion does not take place quantitatively, and there remains free iodine and potassium hydroxide in the solution; the latter is partially converted by the ozone into potassium dioxide, so that finally the solution contains potassium iodate,.potassium hydroxide, and potas- sium dioxide. Hydrogen peroxide 1s not formed. When the solution is acidified, a third part of the iodine, equivalent to the ozone, is liberated at once, whilst the reaction with the hydrogen peroxide liberated from the potassium dioxide is only complete after 1-2 hours. Manganese dioxide when heated in a current of carbonic auhydride at 400°, and to an incipient red heat, does not yield ozone. In a current of oxygen at 400°, 6.5 grams of the dioxide gave in one hour 9.57 milligrams of ozone ; at an incipient red heat, it gave 7-46 milli- The gas examined was evolved at a temperature of 320'.94 ABSTRACTS OF CHEMICAL PAPERS.grams. The forrriation of ozone from a mixture of potassium chlo- rate and manganese dioxide increases with the amount of manganese dioxide ; manganous oxide acts i n a similar way to the dioxide, but much less ozone is formed. Cobalt oxide, Co203, behaves in a similar way to manganese dioxide, but in the presence of nascent oxygen the amount of ozone formed is greater in proportion to the amount of cobalt oxide employed. The compound K2Co,0,,, prepared by fusing cobalt carbonate with potassium hydroxide, when heated at 200° gives off three atoms of oxygen, but no ozone is formed. Nickel oxide behaves in a similar way to the above; apparently, it is not; altered by heating i n oxygen, and after heating some time still evolves chlorine when treated with hydrochloric acid, and ozone when again heated in oxygen. The reaction with potassium chlor- ate takes place violently at 300°, and less ozone is formed than in the case of cobalt.Silver oxide, when heated in a current of carbonic anhydride at 350', gives only a slight trace of ozone, which is probably due to the action of the oxygen formed on nndecornposed oxide; in a current of oxygen a t 280°, it forms ozone. Silver peroxide was prepared by the electrolysis of silver nitrate ; 1.22 gram heated at 300' gave 7.68 milligrams of ozone. Only a very small quantity of oxygen is evolved from a mixture of silver oxide and potassium chlorate a t 360° ; above 400°, the chlorate decomposes slowly without the formation of ozone. Mercuric oxide when heated at 400" does not give off ozone, but when heated in n current of oxygen, a small quantity of ozone is formed ; probably the greater part of the ozone is destroyed by the metallic mercury.With potassium chlorate, it behaves in a similar way to silrer oxide. Lead peroxide yields ozone when heated either in a current of carbonic anhydride or of oxygen, but with potassium chlorate at 320-350', only n very small quantity of ozone is formed, and the peroxide is reduced to red lead and litharge. When heated to redness in a current of oxygen, red lead and litharge yield small quantities of ozone. Cbromic anhydride (3.39 grams), when heated a t 260-280°, yields ozcne (1.52 milligram). Chromium oxide heated at 400' in a current of oxygen, yields small quantities of ozone. Uranimn trioxide does not yield ozone in an atmosphere of carbonic anhydride ; in oxygen, small quantities of ozone are formed.When heated with potassium chlora'te, i t yields potassium uranate and chlorine. The hydrate of the tetroxide, when heated at 150" in a current of carbonic anhydride, yields water and oxygen, but no ozone is formed, as probably hydroxyl groups are eliminated, which decompose irit o water and oxygen. The author was unabie to detect, the formation of ozone from platinum oxide, as the compound always contains chlorine, which is evolved on heating. Gold oxide was prepared by precipitation of gold chloride with potassium hydroxide; the mixture is acidified with sulphuric acid, and the precipitate dissolved in nitric acid,IKORGANIC CHEllllSTRP. 95 reprecipitated by dilution with water, and dried at 150’; 1.44 grams of the oxide heated in a curreiit of carbonic a.nhydride at 830-280O gaTe 21 milligrams of ozone, and 1.85 grams heated in oxygen gave 54.4 milligrams of ozone.E. C. R,. The so-called Oxysulphazotic acid or Nitrosodisulphonic acid. By ARTHUR R. HANTZSCH and WILLTAM SEMPLE (Bey., 1895, 28, ‘L744--2751).-Potassium nitrosodisulphonate, ON(SO,K),, pre- pared by the oxidation of potassium liydroxylaminedisulphonate by means of lead peroxide, has, according to Raschig, the formula (S03K),N- /o\ -N(S03K),; to this the authors make the following ‘O/ objections: (1) The group :NE‘N: has never previously been ‘O/ observed, and it3 chroniophoric character Las not been proved ; (2) the acidic character of two linked pentavalent nitrogen atoms is unique; (3) the difliculty of explaining the change of colour from orange-yellow t o deep violet-blue which takes place when the salt is dissolved; (4) when reduced, no hydrazine derivatives are formed. The authors regard the compound as a derivative of nitric peroxide with the simple formula ON(S03K),, the oxidation of nitrous acid to nitric peroxide, and of potassium hydroxylaminedi- snlphonate to potassium nitrosodisulphonate being analogous, the relationship between the yellow solid salt and the blue solution is similar to that between colourless solid N204 and coloured NOz.Cryoscopic: molecular weight determinations failed to give satisfac- tory results on account of the instability of the compound. I f the oxidation of the hyclroxyiamine derivative is incomplete, blue crystals axe formed ; these are also obtained by mixing solutions, saturated a t 40°, of potassium hrdroxylaminedisulphonate (3.5-4 parts) and potassium nitrosodisnlphonate (1 part), and consist of solid solutions containing 1-4 per cent.of the latter in the former. The colour of the crystals varies, according to the composition, from ultramarine to sky blue, they are comparatiwly stable, and the content of nitroso- disulphonate may be determined by means of potassium iodide and acetic acid, titrating the liberated iodine with potassium thiosul- phate. Raschig’s potassium nitrosotrisulphonate, (SO,K),N< g>N (SO.,K),, formed by the action of water on potassium nitrosodisulphonate, is also regarded as monomolecular ON (SO,K), ; crSoscopic molecular weight determinations were unsatisfactory, and the electrolytic con- ductivity of its solution does not follow Ostwald’s rule, but it is similar to “ dibenzsulphhydroxamic acid,” ON(S02Ph),, the mole- cular weight of which agrees with the formula.Raschig’s objection to the simpler formu!a for potassium nitrosotrisulp~ion~t~ was based on its non- formation by the oxidation of potassium azotriaulphonate,$6 ABSTRACTS OF CHEMICAL PAPERS. N(S03K)3; but this has little weight since tertiary ammonium de- rivatives do not yield amiiie oxides, ONR3, when oxidised. Dinitrososulphonic acid (Nitroxysulphurous acid). By ARTHUR R. HANTZSCH (Ber., 1895, 28, 2751-2754) .-The author replies to Divers and Haga’s criticisms (Trans., 189.5, 452) of his previous paper on this subject (Abstr., 2895, ii, 75).Their state- ment that he believes in the existence of two potassium nitroxysul- phites is based on a misapprehension, as reference t o his paper shows, and he takes exception to their formula OK*N:NO-SO,K on the following grounds : (1) The salt, being similar to nitrosylsulphuric acid, O:N*O*SO,H, should be readily hydrolysed to sulphuric acid and hyponitrous acid; actually it is, in alkaiine solution, very stable. (2) Until decomposed it does not give the reactions of the sulphates as might be expected. (3) Their general remarks on acids and bases are in conflict with the theory of dissociation. (4) The fact that alkyl hydrogen sulphates are not directly precipitated by barium chloride is explained by the fact that all alkyl derivatives are non- electrolytes.The above objections do not apply to the author’s formula O< “OK I with which Raschig’s ON.N(OK)*SO& may be tautomeric (compare Divers and Haga, Trans., 1895, 1098). J. B. T. NS03K’ J. B. T. Formation of Hydrogen Selenide. By H. ‘PELABON (Compf. rend., 1895, 121, 401-404 ; compare Abstr., 1894, ii, 135 and 447).-- In order to avoid any error that may arise from the fact that when selenium is heated in a mixture of hydrogen and hydrogen selenide, it absorbs a certain quantity of the latter, which is partially liberated on cooling, the author has determined by Ditte’s method the composi- tion of the gas obtained by heating hydrcjgen at various tempera- tures in presence of the smallest possible excess of selenium.The relation pl/p2 of the partial pressure of the hydrogen to that of. the hydrogen selenide was determined for each temperature, and the results are expresscd with great accuracy by the equation of Gibbs and Duhem, log (p!/p2) = M/T + N log T + Z, in which M, N, and Z are constants, ‘I’ is the absolute temperature of the experiment, and the logs are Napierian logs. Experiments at 350°, 440°, and 510° give 13170.3, 15.53, and 119-88 respectively for the values of M, N, and Z . I t follows from the equation that the ratio r = pz/pl + p2 should have 8 maximum value at the temperature t when t = M/N -273. With the values already given for M and N, t = 575O, and this de- duction is confirmed by experiment. I t also follows from Duhem’s equations and the values found for M and N that the heat of forma- tion of hydrogen selenidc should be -17380 minor calories, whereas Fabre’s experiments gave the ralue -18000.C. H. B. Tellurium. By LUDWIG STAUDENMAIER (Zeit. anorg. Chem., 1895, 10, 189--221).-‘l‘elluric acid is most easily obtained by dissolving tellurium in an excess of dilute nitric acid and then adding a slight excess of chromic acid. The solution is evaporated to crystallisation andINORGANIC OHEMISTRP . 97 tlie crystals mashed with nitric acid and dissolved in a small quantity of water. The solution is treated with a few drops of alcohol to reduce any chromic acid remaining, and precipitated by the addition of nitric acid. Finally, the product is dissolved in water and eva- porated t o dryness on the water bath.Telluric acid separates from water at the ordinary temperature in crystals, with 2H20, belonging to the irregular system; these are stable in the air, and are not hygroscopic. When precipitated from its aqueous solution with nitric acid, regular crystals resembling lead nitrate are obtained, together with tho ordinary modification ; these also contain 2H,O. From solutions at O", it crystallises with 6H20 in large, tetragonal crystals resembling monopotassium phosphate ; these crystals effloresce at the warmth of the hand, and are converted into the ordinary modification. When dried over phosphoric acid, they do not decompose even in a vacuum. Pure tellurium compounds are obtained from the crude Hungarian tellurium as follows. The finely powdered substance is dissolved in dilute nitric acid, the solution evaporated with strong hydro- cliloric acid, and filtered ; the tellurium is then precipitated from t h e filtrate with sulpliurous acid, and after being washed with hydrochloric acid and water, it is dissolved in nitric acid, oxidised with chromic acid, and the telluric acid treated as described above.The atomic weight of tellurium was determined in accordance with the following equations H2TeO4,2H,O = Te02 + 0 + 3H20 o r Te + 3 0 + 3H20 and Te02 = Te + 0,. The Erst decomposition is brought about by heating in a glass flask. The reduction in the second and third decomposition is performed as follows. The telluric acid o r dioxide is mixed with finely divided silver and pure silica, and the mixture contained in a platinum or porcelain boat, cGvered with a layer of finely divided silver.The admixture with silver prevents the slightest trace of tellurium from volatilising. The mixture is first heated in a glass tube until the telluric acid i s dehydrated, then in a current of hydrogen, while the temperature is gradually raised from 250' to 400°, and finally for a short time at a, dull red heat. The results of all the experiments (number of experi- ments not stated) agree closely with 127.6 (0 = 16) for the atomic weight of tellurium. Experiments on the fractionai crystallisation of telluric acid are described, which show tliat all fractions give the same atomic weight. The author discusses a t length the work of Brauner (Trtms., 1889. 382 ; 1895, 549) and of Retgers (Zeit.physika1.Chem., lk93,12; 596): E. C. R.. A Hydrate of Arsenic Trisulphide and its Decomposition by Pressure. By WALTH~RE SPRING (Zeit. anorg. Chem., 1895, 10, 185-188) .-The hydrate, As2& + 6H20, is obtained by precipitating a solution of arsenic trichloride containing hydrochloric acid with hydrogen sulphide, and drying the precipitate in a current of air having a relative humidity of 70 per cent. at the ordinary tempera-. tnre. It has a somewhat lighter yellow colour than ordinary arsenic trisulphide, and easily loses its water when warmed. The sp. gr. = 1.8806 at 25*Cio, and the specific volume = 53.174,; whereas the98 -4BSTRAOTY OF CHEMICAL PAPERS. specific volume of the sum of its constituents As,S, and 6H,O is 50.626, therefore, accordiig to the author's theory, i t must decompose when submitted to pressure. It is, in fact, decomposed quantitatively into water and anhydrous trisulphide when submitted to a pressure of 6000-7000 atmospheres.If the density o€ ice is taken for thc calculation of the specific volume of the hydrate, the number S2-662 is obtained, which shows that the water is present in the solid form. The Compounds of Arsenic with Selenium and of Arsenic, Selenium, and Sulphur. By EMERKH SZARVASP (Bey., 1895,28,2654 -2661 ; compare Clever and Muthmann, this vol., ii, 18).--A~senic pentaselenide, AsLSe5, was prepared by heating the two constituents in the requisite proportion in sealed tubes filled with nitrogen ; it forms a black, lustrous, brittle mass, and may be purified by fractional distil- lation under diminished pressure.It is not readily acted on by the ordinary solvents, but fuming nitric acid oxidises it to selenious and arsenic acids. Alkaline hydroxides and hydrosulphides readily dis- solve it, but the resulting yellow solutions decompose when exposed to the air, and, when acidified with the mineral acids, yield the penta- selenide in the form of a reddish-hrown, fiocculent precipitate. Vapour density determinations made a t 750-800° show that the molecule of As,Se, has undergone decomposition, probably into As,Se, and Se,; at still higher temperatures (1050-1100') the vapour density shows that the molecule of As,Se5 has split up into three simpler molecules. Sodium monosdenoarsenate, Na3As0,Se + 1!2H,O, is one of the compounds formed on dissolving arsenic pen taselenide in sodium lijdroxide, but as the solution readily decomposes when exposed to the air, it is necessary to work in an atmosphere of hydrogen.The salt may be obtained as colourless crystals on the addition of methylic alcohol to the aqueous solution; the crystals, when left exposed to the air, lose their water of crystallisation arid turu red, owing to the liberation of selenium. Sodium selenoarsennte, Na&Se4 + 9Hz0, obtained together with the preceding compound K hen arsenic pentaselenide is dissolved in sodium hydroxide, ci-ystallises in rub y-red needles, which rapidly :ose their water of ciytallisation when exposed to the air; it is readily soluble in water, and the aolutiou readily undergoes decomposi- tion, selenium being deposited. Mineral acids tlirow down the penta- selenide from its alkaline solutions i n the form of a reddish-brown flocculent precipitate.Arsenic triselenobisulphide, As,Se3Sz, is obtained when arsenic bi- sulphide and selenium are heated together in the requisite propor- tions in an atmosphere of nitrogen; it is best purified by repeated distillation under low pressure, and then forms ablack, highly glistening substance which, in thin plates, has a purple-red colour. Tn chemical properties it resembles arsenic pentaselenide ; it is soluble in alkalis, and is precipitated unaltered on the addition of' an acid. Vapour densi- ties taken at 550-600' indicated that dissociation had taken place. Arsenic diselenotersu/phide, As,SepS2, may bc obtained in a similar manner from arsenic tersulphide and selenium.It differs from the E. C. R.INORQANlO CHEMISTRY. 99 preceding compound in being ruby-red in thin plates. density at 750’ indicates that dissociation has taken place. The vttpour J. J. S. Atomic Weight of Helium. By N. A. LANGLET (Zeit. anorg. Chew,., 1895, 10, 289-29d).-The helium was prepared as follows. A hard glass tube, 1 metre long, is filled first with a column (10 cm. long) of manganese carbonate, then with a mixture of powdered cleveite (3 parts) and potassium pyrosulphate (2 parts), and then with a column (10 cm. long) of copper oxide. The air is expelled from the tube by carbonic anhydride, the copper oxide heated to redness, and the tube then heated, as in the case of an organic analysis.The gas produced is collected over 50 per cent. potassium hydroxide, and finally passed through a tube containing layers of copper oxide, phosphoric anhydride, and magnesium powder, the copper oxide and magnesium being heated to redness. The gas so prepared, when examiiieii spectroscopically in a Giessler’s tube, was found t o be free from nitrogen, hydrogen, and argon. The density was determined by weighing 100 C.C. in a glass balloon, and was found to be 0.139 (air = 1) or 2-00 (H = 1). The velocity of sound in the gas was then determined, and from this the ratio of the specific heats at con- stant pressure and at constant volume. The ratio. obtained = 1.B7, whence the molecule of helium contains only one atom, and the atomic weight = 4. Combination of Magnesium with Argon and with Helium.By LOUIS J. TROOST and L ~ O N V. R. OUVRARD (Compt. reiad., 1895,121, 394--395).-It is not indispensable to pass a mixture of argon and helium with nitrogen over red-hot magnesium or lithium before intro- ducing it into the spectrum tubes. The tubes are furnished with mag- nesium wires, and a RuhmkorE coil is used which has a Marcel-Deprez contact breaker. The dry gas is introduced, and a powerful current is passed. At first the nitrogen is slowly absorbed, but when the pressure is reduced to a certain point, the magnesium wires become very hot, and the nitrogen combines with the metal very rapidly. The nitrogen spectrum disappears, and that of helium or argon, 01’ both, becomes visible. If a powerful discharge is continued for some time, the argon and helium disappear, seemingly because they combine with the vupou~ of the magnesium.Platinum under similar conditions seems likewise to volatilise and combine with argon. E. C. R. C. H. B. Argon, a New Constituent of the Atmosphere. By LORD RAYLEIGH and WI LLraM R.AMSAY (PhiE. Tram., 1895, 186, 187-241). -It has been shown by Rayleigh that nitrogen extracted from chemical compounds is about 4 per cent. lighter than “atmospheric nitrogen ” (Abstr., 1895, ii, 444j, the chemically prepared nitrogen pre- viously used having been obtained from nitric oxide, from nitrous oxide, find from ammonium nitrite by the use ot: hot iron. As i t appeared desirable to show that the agreement of numbers obtained for chemical nitrogen does not depend on the use of no red heat in the process of purification, experiments were tried with nitrogen liberated from100 ABSTRAOTS OF GHEMfCAL PAPERS. carbamide by tho action of sodium hypobromite, which gas it \\-as hoped would require no further purification than drying.But the gas so obtained was obviously contaminated, attacked vigorously the mercury of the T6pler pump, and was desci-ibed as smelling like a dead rat. Its weight proved to be in excess even oE the weight of atmospheric nitrogen, and it was only after passing the gas over hot metals that the corrosion of the mercury and the evil small were in great degree obviated, and the weight was found to correspond with that of the chemical nitrogen previously examined. Nitrogen can, however, be prepared from ammonium nitrite without the employ- merit of hot tubes, which, in spite of a slight nitrous smell, shows no appreciable difference in density from that prepared by treatment with hot metals.To the above list may be added nitrogen, prepared in yet another manner, whose weight was determined subsequently to the isolation of the new dense constituent of the atmosphere ; in this case the nitrogen was actually extracted from air by means of magnesium. The nitro- gen thus separated was then converted into ammonia by the action of water on the magnesium nitride, and afterwards liberated in the free state by means of calcium hypochlorite. The purification was con- ducted in the usual way, and included in one case passage over red- hot copper and copper oxide, but this was subsequently omitted.With or without exposure to red-hot copper, the " chemical " nitro- gen derived from " atmospheric " nitrogen possesses the usual density. Experiments were also made to prove that the ammonia produced from the magnesium nitride is identical with ordinary ammonia, and contains no other compound of a basic character. For this purpose, the ammonia was converted into ammonium chloride and the percent- age of chlorine determined by titration with a solution of silver nitrate, which had been standardised with pure sublimed ammonium chloride. It was found that ammonium chloride prepared from mag- nesium nitride obtained by passing atmospheric nitrogen over red-hot magnesium contains practically the same percentage of chlorine as pure ammonium chloride. It may be concluded, therefore, that red- hot magnesium withdraws from atmospheric nitrogen no substance other than nitrogen capable of forming a basic compound with hydrogen.That the discrepancy between the weights of chemical and atmo- spheric nitrogen cannot be due to the presence of known impurities has already been proved (Zoc. c i t . ) . I t was thought that the lightness of the gas extracted from chemical compounds might be explained by partial dissociation of nitrogen molecules N2 into detached atoms. But as the silent electric discharge has no effect on the density of either kind of gas, and as the density of a sample of chemically pre- pared nitrogen showed no sign oi' increase after storage of the gas for eight months, this view had to be abandoned.Regarding it a s established that one or other of the gasetl must be a mixture, the simplest assumption, in view of the above facts, was to admit the existence of a second ingredient in air, from which oxygen, moisture, and carbonic anhydride had already been removed. If the density of the supposed gas were double that of nitrogen, Q per cent. only byINORGANIC CHEMISTRY. 101 volume would be needed, or, if the density were but half as much again as that of nitrogen, then 1 per cent. would still suffice. The positive evidence i n favcur of the prevalent doctrine that the inert residue from air after withdrawal of oxygen, water, and car- bonic anhydride is all of one kind appears to be derived from the experiments of Cavendish (Phil. Trans., 1785,75,372). By sparking a mixture of air and oxygen in the presence of alkali for the absorp- tion of the acid product of the reaction, and subsequent removal of the excess of oxygen by a solution of liver of sulphur, Cavendish found that only a small biibble of air remained unabsorbed, “ which certainly was not more than 1/120th of the bulk of the ” nitrogen “ let up into the tube,” and therefore concluded “that if there is any part of the ” nitrogen “ of our atmosphere which differs from the rest, and cannot be reduced to nitrous acid, we may safely conclude that i t is not more than 1/120th part of the whole.” Cavendish was satisfied with this result, and does not decide whether the small residue was genuine, but the experiment8 hereafter described render i t not improbable that his residue was really of a different kind from the main bulk of the nitrogen, and contained the gas now called argon.With a, view of isolating, if possible, the unknown and overlooked constituent, or, i t might be, constituents, the existence of which in atmospheric nitrogen had thus been rendered probable, this gas waR submitted to examination. The earliest attempts to isolate the suspected gas were made by the method of Cavendish, using a Ruhmkorff coil of medium size actuated by a battery of fire Grove cells. When the mixed gases were in the right proportion, a rate of absorption of about 30 C.C. per hour could be attained. In a particular instance, starting with 50 C.C. of air and <gradually adding oxygen, the volume was a t length reduced to 1 C.C.On treatment with alkaline pyrogallol, the gas shrank to 0.38 C.C. That this small residue could not be nitrogen was argued from the fact that it had withstood the prolonged action of the spark, although mixed with oxygen in nearly the most favourable proportion. To this residue another 50 C.C. of air was added, and the whole worked up with oxygen as before. The residue was now 2.2 c.c., and after removal of oxygen 0.76 C.C. In another case, a mixture of 5 C.C. of air with 7 C.C. of oxygen was sparked for one hour and a quarter, the residue was 0.47 c.c., and, after removal of oxygen, 0.06 C.C. Several repetitions giving similar results, it became clear t h a t the final residue did not depend on anything that might happen when sparks passed through a greatly reduced volume, but was ilz proportion to the amount of air operated on.I3ifficulty was experienced in accumulating a sufficient quantity for examination of the residue which refused to be oxidised, owing, as was proved later on, to the solubilityof the gas in water. At length, however, a sufficiency was collected to allow of sparking in a specially constructed tube, when a comparison with the air spectrum, taken under similar conditions, proved that, a t any rate, the gas was not nitrogen. Since nitrogen, at a bright red heat, is easily absorbed by ma& nesium, best in the form of turnings, an attempt was successfully VOL. LXX. ii. 9102 ABSTRACTS OF CHEMICAL PAPERS made to remove that gas from the residue left after eliminating oxygen from air by means of red-hot copper.In zt preliminary experiment, i n which a quantity of atmospheric nitrogen was admitted into contact with red-hot magnesium, pumped off, and then treated again with fresh magnesium, the original volume of LO94 C.C. was reduced to 50 c.c., which resisted rapid absorption. It still contained nitrogen, however, judging by the diminution of volume which it experieneed when allowed to remain in contact with red-hot mag- nesium. Its density was, nevertheless, determined by weighing a small bulb of about 40 C.C. capacity, first with air and afterwards with the gas. The density found was 18-88, and the gas, therefore, was heavier than air. An arrangement was then adopted by means of which a quantityof atmospheric nitrogen could be brought repeatedly into contact with fresh quantities of magnesium heated to redness.About 10 litres of gas were taken and treated in this manner, until the volume was reduced to 200 C.C. Unfortunately some of the nitrogen was lost by leakage, so that exact measurements could not be taken. The density of this residual gas was found to be 16.10, but as i t appeared advisable to continue the absorption of nitrogen, it was again treated with fresh magnesium. The volume was thus reduced to a little over 100 c.c., and the density was now found to be 19.086 (0 = 16). A portion of the gas was then mixed with oxygen, and submitted to a rapid discharge of sparks for four hours in presence of caustic potash. It contracted, and on absorbing the excess of oxygen with alkaline pyrogallol, the contraction amounted to 15.4 per cent.of the original volume. If the gas contained 15.4 per cent. of nitrogen of density 14.014, and 84.6 per cent. of other gas, the density of the mixture being 19.086, calculation leads to the number 20.0 for the density of this other gas. A vacuum-tube was filled with a specimen of the gas of density 19.086, and it could not be doubted that it contained nitrogen, the bands of which were distinctly visible. It was probable, therefore, that the density of the pure gas lay not far from 20 times that of hydrogen. At the same time many lines were seen which could not be recognised as belonging to the spectrum of any known substance. If atmospheric nitrogen contains two gases of different density, it should be possible to obtain direct evidence of the fact by the method of atmolysis, and experiments were made with this object.The atmolyser was prepared by combining a number of churchwarden tobacco pipes ; eight pipes connected in simple series, and placed in a large glass tube, closed in such a way that a partial vacuum could be maintained in the space outside the pipes by a water-pump, giqing the best results t'lius obtained. One end of the combination of pipes was connected with the interior OE an open bottle containing sticks of caustic alkali, the object being mainly t o dry the air. The other end of the cornbination was connected to a bottle aspirator, initially full of water, and so arranged as to draw about 2 per cent. of the air which entered the far end of the pipes. The air thus obtained was treated exactly as ordinary air had been treated in determinations of the density of atmospheric nitrogen.The density of the gas from theINORQANIC CHEMlSTRY. 103 above prepared air was in every case greater than that from unpre- pared air, and to an extent much beyond the possible errors of ex- periment. The conclusion seems inevitable that " atmospheric nitrogen " is a mixture and not a simple body. To complete the verification, negative experiments were made to prove that argon is not derived from nitrogen or from chemical sources. In one case 3 litres, alrd in another case about 59 litres of chemical nitrogen, prepared from ammonium nitrite, were treated with oxygen i n precisely tho manner in which atmospheric nitrogen had been found to yield argon.The final residue was in neithercasa more than 3.5 c.c., and this consisted mainly of argon, the source of which is to be found in the water used for the manipulation of the large quantities of gas employed. If atmospheric nitrogen had been used, the final residue should have been about 10 times the above amount. A similar set of experiments was carried out with magne- sium, and led to the same conclusion. A description is given of the methbds adopted for the separation of argon on a large scale, both by the oxygeu and the magnesium process. In the latter case, a quantitative experiment was carried out on a large scale, the amount of argon from 100 litres of '' atmo- spheric " nitrogen, measured at Z O O , being collected after treatment with magnesium, and measured at 12'.An accident led to the loss of about 4 litres of nitrogen during the process, and the total residue, after absorption of the nitrogen, being 921 c.c., the yield is therefore 0.986 per cent. It may be concluded, wibh probability, if allowance be made for the solubility of the argon in the water over which i t was collected, that argon forms approximately 1 per cent. of the atmospheric nitrogen. This result is confirmed by determinations in which the oxygen method of absorption was used, two independent observations giving 1.04 aud 1.03 as the percentage of argon in atmospheric nitrogen. Determinations of the density of argon prepared by means of oxy- gen, and of argon prepared by means of magnesium were made, A single determination of the gas obtained by the first method gave 19.7, and the mean of three results obtained with gas prepared by the second process was 19.88.The spectmm of argon has been examined by Crookes, and forms the subject of a separate communication. Seen in a vacuum tube of about 3 mm. pressure, it consists of a great number of lines, dis- tributed over almost tbe whole visible field. Two lines are specially characteristic ; they are less refrangible than the red lines of hydrogen or lithium, and serve well to identify the gas when examined in this way. The wave lengths of these lines are 696.56 and 705.64 x loR6 mm. Besides these red lines, a bright yellow line, more refrangible than the sodium line, occurs at 603.84. A group of five green lines occurs next, of which the second is perhaps the most brilliant, and has the wave length 561.00.There is next a blue line of wave length 470.2, and then five strong violet lines of which the fourth is the most brilliant, and has the wave length 420.0. When the current is passed from the induction coil in one direction, that end of the capillary tube next the positive pole appears of a redder, 9-2104 ABSTRACTS OF CHEMICAL PAPERS. Temp. and that next the negative of R bluer hue. There are, in effect, two spectra, which Crookes has succeeded in separating to R considerable extent. A phenomeuon of this order has been attributed to the presence of two gases, and the conclusion would follow that argon is in reality a mixture of two gases, which have as yet not been sepa- rated. This conclusion is, if true, of great importance, and experiments are i n progress to test it by other physical methods. Crookes and also Schuster have proved the identity of the chief lines of t'he spectrum of gas separated from air-nitrogen by aid of magnesium with that remaining after sparking air-nitrogen with oxygen, in presence of caustic soda solution. The solubility of argon in water bas been already alluded to, and special experiments were tried to determine the degree of solubility.The course marked out by Bunsen was followed. The solubility of the gas isolated by means of oxygen was found to be 3.94 per 100 of water at 1 2 O , and argon prepared by means of magnesium gave a result of 4.05 per 100 of water. The solubility is therefore about 2& times that of nitrogen. The fact that the gas is more soluble than nitrogen led to the expectation of finding it in increased proportion i n the dissolved gases of rain water, an anticipation which experiment con6rmed. The behaviour of the gas at low temperatures was examined by Olszewski, whose results are published separately.The following tables are given for convenience of reference. Vupour PTessures. Pressure. I Temp. I Pressure. Temp. I--- -- Pressure. - 186' 9' - 139 *1 -138.3 744) -5 mm. 23 -7 atms. 25'3 ,, -134-4 1 29-8 ,, -121.0 Gas i 60.6 ,, i I --- Critical Boiling Freezing Freezing teE$:" pressure. ' I point. , point. 1 pressure. Density I Density Of liquid Coloar of inn of gas. at liquid. point. Nitrogen, N3 ...... Carbonic oxide, co .................. Argon, A, .........Oxygen, O2 ......... Nitric oxide, NO.. ---!-- -'---- atms. mm. O ? O -121'0 50'6 -186'9 -189'6 -118'8 50'8 -18'2.7 ? - 81.8 54-9 -164'0 -1185.8 , - 93'5 1 71'2 1-153.6 -167.0 In order to decide regarding the elementary 01- compound nature of argon, experiments were made on the velocity of sound i n it. From these the ratio of the specific heat at constant pressure to that at constant volume was deduced in the well-known manner. The accuracy of the apparatus used was tested by preliminary observa-INORO ANIC CHEMISTRY. 105 tions with air, carbonic anhydride, and hydrogen, which gave results in agreement with those of other observers. Five series of ineasure- ments were then made with a sample of gas of density 19.86, and the ratio C,/C, of the specific heats found was 1.644.This is practically the theoretical ratio, 1.66, for a monatomic gas, that is, a gas in which all energy imparted to i t at constant volume is expended in effecting translational motion. The only other gas of which the ratio of specific heats has been found to fulfil this condition is mercury at a high temperature. A great number of attempts were made to induce chemical com- bination with the argon obtained by use of magnesium, but without any positive result. The following substances were tried under different conditions, but without effect :-(a) Oxygen in presence of caustic alkali, ( b ) hydrogen, ( c ) chlorine, ( d ) phosphorus, (e) sul- phur, (f) tellurium, (9) sodium, (h) fused and red-hot caustic soda, (i) soda-lime at a red heat, ( j ) fused potassium nitrate, (k) sodium peroxide, ( I ) persulphides of sodium and calcium, (m) nitro-hydro- chloric acid, (n) bromine water, (0) a mixture of potassium perman- ganate and hydrochloric acid, ( p ) argon is not absorbed by platinum- black.Argon is, therefore, most astonishingly indifferent, inasmuch as it is not attacked by elements of very opposite character ranging from sodium and magnesium on the one hand, to oxygen, chlorine, and sulphur on the other. It will be necessary to try whether tho inability of argon t o combine a t ordinary or at high temperatures is due to the instability of its possible compounds, except when cold. Mercury vapour at 800" mould present a similar instance of passive behaviour. The authors finally discuss the probable nature of the gas or gases which they have succeeded in separating from atmospheric air, and which has been provisionally named argon.It has been shown that argon is present in the atmosphere, and is not manufactured during the process of separation, and it is practically certain that the argon prepared by means of electric sparking with oxygen is identi- cal with argon prepared by means of magnesium. That argon is an element or mixture of elements, may be inferred from the obssrva- tions on the ratio of the two specific heats. For if argon molocules are di- or polyatomic, the atoms acquire no relative motion, even of: rotation, a conclusion improbable in itself and one postulating the sphericity of such complex groups of atoms. But a monatomic gas can be only an element., or a mixture of elements; and hence it follows tbat argon is not of a compound nature.Argon is approxi- mately 20 tinies as heavy as hydrogen, that is, its molecular weight is 20 times as great as that of hydrogen, or 40. But its molecule is monatomic, hence its atomic weight, or, if it be a mixture, the mean of the atomic weights of the elements in that mixture, taken for the proportion in which they are present, must be 40. There is evi- dence both for and against the hypothesis that argon is a mixture ; for the present, however, the balance of evidence seems to point to simplicity. If argon is a single element of the atomic weight 40, no vacant place can be assigned to it in the periodic system, and there is then106 ABSTRAOTS OF OBEMICAL PAPERS.reason to doubt whether the periodic classification of the elements is complete ; whether, in fact, elements may not exist which cannot be fitted among those of which i t is composed. On the other hand, if argon is a mixture of two elements, they might find R place in the eighth group, one after chlorine and one after bromine. It would be difficult, however, in this case to account for the heavier element having escaped detection. If it be supposed that argon belongs to the eighth group, then its properbies would fit, fairly well with what might be anticipated. For the series which contains might be expected to elid with an element of monatomic molecules of no valency, that is, incapable of forming a compound, or if forming one, being an octad ; and it would form a possible transition to potas- sium, with its monovalence, on the other hand. As for the physical condition of argon, that of a gas, we possess no knowledge why carbon, with its low atomic weight, should be a solid, while nitrogen is a gas, except i n so far as we ascribe mole- cular complexity to the former and comparative molecular simplicity to the latter.Argon, with its comparatively low density and its molecular simplicity, might well be expected t o rank among the gases. And its inertness, which has suggested its name, sufficiently explains why it has not previously been discovered as a constituent of compound bodies. Assuming provisionally that it is not ;t mixture, the symbol A is suggested for this element. In addenda by Ramsay, further determinations of the density of argon are given, the general mean being 19.900.The value of R in the gas equation R = p v / T , has been determined between -89" and +248O. The numbers show that argon nndergoes no molecular change within these limits of temperature. Further determinations of the ratio of the two specific heats were also made, the general mean being 1.643. H. C. A Singular Case of Metallic Precipitation. By J. B. SEN- DERENS (Bzill. SOC. Chim., 1894, [3], 11, 424-426; compare Abstr., 1895, ii, 315).-When bright lead is immersed in a solution of lead nitrate containing from 10 to 400 grams per litre, and protected from access of air, metallic lead is gradually precipit'ated on it in well- defined crjstals, just as on iron or zinc. A certain amount of lead nitrite is produced a t the same time, and in weaker solutions forms the exclusive product, being deposited in yellow crystals in place of those of the metal.The lead crystals form plates from 1 to 4 mm. in diameter, and are chemically pure, but they rapidly oxidise in air to the hydroxide, so that a ci-ystallographic examination is impracticable. When kept undisturbed in the original liquid, the metallic crgstnls are gradually converted into a basic nitrate, which crystallises in large, white tufts of silky needles as much as 2 cm. in length. The precipitation of the lead is not due to local electrolytic action set up by metallic impurities, for precisely the same result is ob-INORQAKIC CHEMISTRY. 107 tained with pure lead made by reducing, by means of sugar-charcoal, litharge prepwed from the pure nitrate (compare, however, Zoc.cit.) ; moreover, the precipitation does not occur in solutions of lead acetate, as would be tbe case i f it were due to this cause. JN. W. Double Halogen Salts of Ammonium and Copper. By HORACE L. WELLS and E. B. HURLBURT ( Z e i t . nno~g. Chem., 1895, 10, 157-lGO, and Amey. J. Sci., 1895, [3], 50,390--393).-The chloride, 4NH4C1,Cu,Cl,, is obtained by cooling a mixed solution of its com- ponent salts containing hydrochloric acid, copper wire being placed in the liquid ; a large excess of ammonium chloride must be used ; it crystallises in colourless pIisms, which, on exposure to air, quickly turn brown and then green. The chloride, 4NH4C1,3Cu,C12, is obtained when its component salts are dissolved in the proper proportions in dilute hydrochloric acid ; it crystallises in lustrous, colourless dodecahedra, and is fairly stable on exposure to air, but gradually turns green. The byomide, 4NH4Br,Cu2Br2, obtained in a similar way to the cor- responding chloride, crystallises in long, colourless prisms, and is much more stable than the corresponding chloride; on exposure t o air, it gradually turns green. The bromide, 2NH4Br,Cu,Brz + HzO, is obtained if an excess of cuprous bromide is present ; it crystallises in lustrous, colourless rhombohedra, and is more stable than the pre- cediug salt.The iodide, 2NH4I,CuzI2, is the only salt obtained even when the Components are employed in very diff ereat proportions. E. C . H. Formation of Nickel Carbonyl. By HG. PREY (Bey., 1895, 28, 2512-2514) .-Sodium decomposes ethylic oxalate into ethylic car- bonate and carbonic oxide. When ethylic oxalate is added to finely divided nickel chloride and sodium, suspended in light petroleum, traces of nickel carbonyl are found in the gas which is evolved, but the amount present is so small that no liquid can be obtained. Ferric chloride, when treated in the same way, gave no trace of iron carbonyl. A. H. Double Salts of CEesium Chloride with Chromium Tri- chloride and Uranyl Chloride. By HORACE L. WELLS and B. B BOLTWOOD ( Z e i t . nnorg. Chem., 1895, 10, 181-184 ; also Amer. J. Sci., 1895, [3], 50,254-258).-The chloride, 2CsCI,CrCl, 1- H20, is obtained by saturating warm solutions of its component salts with hjdrogcn chloride, and corresponds with the double chlorides prepared b j Neumann (Abstr., 1888, 655). It crystallises in aggregates of small, reddish-violet crystals, is stable on exposure to air, does not give up its water of crystallisation at loo", and dissolves slowly in water form- ing a green solution. The chloride, 2CsC1,CrCl3 + 4H20, is obtained from a cold solution of its components by sa-turating it with hydrogen chloride, or by evaporation over sulphuric acid; it crystallises i n green, monoclinic crystals, is somew hat hygroscopic, very easily soluble in water, and when heated at 110" loses 3H20, and is converted into the abore violet salt. The aiithors point out that wheraas green chromium sulphate contains less water than the Fiolet modificatior ,108 ABSTRACTS OF CHEMIOAL PAPERS. the reverse is t,he case with the double czsium salts, and that there- fore probably the green colour of the salts is not due t o the formation of basic salts and free acid, or of acid salts. The chloride, 2CsC1,U02CI,, prepared in a similar way to the above, corresponds with the double salts already described ; it crystallises in beautiful yellow, rhombic leaflets. JL C. R. Chemical Behaviour of Pyrites and Mareasite. By AMOS P. BROWN (Proc. Amer. Phil. Soc., 1894, 33, 225-243). See Abstr., 1895, ii, 316.-The constitution here deduced for marcasite is the same at3 that given by Loczka (Abstr., 1895, ii, 20) for pyrites, namely, ,-4 Fe<$ L. J. S.