15% RUSSELL ANb SMITH : NON-EXISTENCE OF THE GASEOUS CLIL-Nnn-existence of the Gaseous Sulphide of Carbon described by Denirqer. By EDWARD JOHN RUSSELL and NORMAN SMITH. IN 1895, Deninger (J. p . Chenz., [ii], 51, 346) described a gas which he considered to be a new sulphide of carbon having the formula CS. He prepared it (1) by heating together in a sealed tube chloroform and sodium sulphide ; (2) by subjecting to the same treatment a mixture of iodoform and silver sulphide ; (3) by the action of sodium on a mix- ture of car'bon disulphide and aniline. The gas was collected over caustic soda, and, although no analytical figures are given, the formula appears to be based on the fact that the sulphur dioxide formed on ex- plosion with oxygen has about the same volume as that of the carbon dioxide produced, No properties of the gas are mentioned save that it burns rapidly and is absorbed by alcohol and aniline.Although no further paper has been published dealing with the gas, descriptions of i t are given in two or three of the newer text-books, which do not, however, add anything to what Deninger has already stated. During the last two pears, we have made many attempts to prepare this compound, but without success, and we are forced to the conclusion that no gas of the formula CS is obtained by any of the methods described by Deninger ; the gases produced are invariably mixtures of known substances. It is known that during the combustion of any gaseous compound of lsulphur some of this element almost always burns t o sulphur trioxide, and only rarely is the whole of it converted into sulphur dioxide.When, for example, carbon disulphide is exploded with oxygen, the volume of the sulphur dioxide is never double that of the carbon dioxide, as required by the equation CS, + 30, = CO, + 2SO,, but is invariably less, the exact amount depending on the conditions of the explosion (Russell, Trans., 1900, 77, 352 ; see also Dixon and Russell, Trans., 1899, 75, 600). Consequently it is impossible to identify any gas frdm the ratio of the carbon dioxide to sulphur dioxide produced during explosion. Equally impossible, of course, is it to assign a formula to a new gas by use of this ratio; yet this appears to be what Deninger has done, Of the three methods described, that depending on the action of sodium on carbon disulphide mas dxamined first, as it seemed to promise a continuous stream of the gas.The instructions given are t o mix 15 grams of sodium in small pieces with 125 C.C. of dry aniline in a 500 C.C. flask, to pour on 150 c,c, of carbon disdphide, and blow outSUEPHIDE OF CARBON DESCRIRED BY DENIKGER. 1530 the small quantities of gas evolved with carbon dioxide. The gas is then to be passed through caustic soda, india-rubber, and triethylphos- phine, and collected over caustic soda. The object of the india-rubber and triethylphosphine is evidently to remove any carbon disulphide that may be carried over ; we made some experiments to see how far they would do this. Hydrogen charged with varying quantities of carbon disulphide was passed through lengths of tubing packed with rubber, but much of the carbon disulphide always remained unabsorbed. This agrees with an observation made by Hofmann (Bey., 1869, 2, 73) that carbonyl sul- phide cannot be completely freed from carbon disulphide by contact with india-rubber.Triethylphosphine in ethereal solution was next tried with a some- what better result, absorption of carbon disulphide being very com- plete at first, but in a short time the absorbing power mas exhausted, and carbon disulphide was easily detected in the escaping gases. This reagent makes an excellent purifier for small quautities of gas, but it is not suitable for large volumes. Aqueous sodium hydroxide only slowly and partially absorbs carbon disulphide. These preliminary trials showed that there was nothing t o prevent Deninger's gas containing carbon disulphide; the fact that it was actually present is indicated by his description of what happened on evaporation of some that he had condensed.H e states that the liquid rapidly diminished in volume, and the boiling point rose to 474 the boiling point of carbon disulphide. Sodium and aniline react t o produce hydrogen, which is therefore another constituent of the gas. Lastly, a mixture of sodium, aniline, and carbon disulphide was found to evolve hydrogen sulphide, slowly a t first, more rapidly afterwards. This was a third substance to be expected in the mixture. Our method of investigation was to estimate the amounts of hydrogen, carbon disulphide, and hydrogen sulphide present, and to see what volume, if any, was left unaccounted for.The analysis was carried out in accordance with the directions given in a previous paper, the detaiIs of which need not be reproduced here (Trans., 1900, TI, 352). Suffice it to say that, after removal of the hydrogen sulphide by lead dioxide, the residual gas was exploded with oxygen, the contraction was read, and the volumes of sulphur dioxide and carbon dioxide produced, and the amount of oxygen used, were determined. From three of the four independent equations thus obtained, it is easy, as shown ii. the above paper, to calculate the amounts of hydrogen and carbon disulphide ; if these values also satisfy the fourth equation, it follows that the results of the explosion are quantitatively accounted 5 ~ 21540 RUSSELL AND SMITH: NON-EXISTENCE OF T H ~ cras~ods for by these two gases, and that it is impossible to admit the presence of any other combustible gas.As a further check, the volumes of the gases found were added together and compared with that originally taken ; any difference might arise from the new gas sought for. A large number of analyses all agreed in showing that Deninger’s gas consists entirely of hydrogen sulphide, carbon disulphide, and hydrogen. The quantities varied considerably, but no evidence of any other constituent could be obtained. I n our experiments, we omitted the india-rubber and triethyl- phosphine purifiers, as being only likely t o introduce complications. Sometimes the gas was collected over potash, and sometimes over mercury; sometimes, too, it was passed through purified lead dioxide t o remove hydrogen sulphide-the result was invariably the same.The two analyses are fairly typical. 1. 2. Hydrogen sulphide .................. 10.0 8.2 Carbon disulphide .................. 19.6 22.1 Oxygen ................................. 1.1 1.2 Hydrogen.. ............................. 64.4 63.7 Nitrogen .............................. 4.3 5.0 Total ........................... 99.4 100*2 Oxygert used in Explosion : Calculated ........................... 83.7 75.1 Found ................................. S2.5 74.4 Equally definite results were obtained when the gas was resolved into its constituents by cooling. The gas was passed through a column of lead dioxide to remove hydrogen sulphide, a bulb surrounded by solid carbon dioxide, another bulb surroiinded by liquid air, and the residual gas collected in a eudiometer over mercury.I t was occasion- ally necessary t o drive the gas forward by carbon dioxide, as the rate of evolution was very slow; this carbon dioxide condensed at the temperature of liquid air, and the gas left uncondensed i n the Iast bulb was driven into the eudiometer a t the end of the experiment by a current of dry air. The separate products were then analysed. (a) The uncondensed portion consisted of hydrogen and air. ( 6 ) The solid which collected in the bulb cooled with liquid air was carbon dioxide. I n neither case could any trace of a sulphur com- pound be detected. ( c ) The bulb cooled with solid carbon dioxide contained a small quantity of a highly refractive liquid, and was sealed off while still surrounded by the cooling agent.It was transferred to the laboratorySULPHIDE OF CARBON DESCRIBED BY DENIKGER. 1541 vessel of the gas analysis apparatus, and the liquid allowed to mix with excess of oxygen, in which it completely volatilised. Analysis showed that the liquid was pure carbon disulphide. Deninger states that the gas is rapidly absorbed by aniline, and that great care is necessary in the preparation, otherwise all the gas is retained by this substance. As i t was possible that we had lost all the gas in this way, we varied the experiment somewhat, and allowed sodium to react with a mixture of equal weights of carbon disulphide and benzene. There was no visible reaction, but carbon dioxide was passed slowly through the mixture and collected without any previous washing.It had, taken up some carbon disulphide and benzene, but there was no iudication of any other gas being present. . The caused 1. 2. Carbon dioxide.. ...................... 61.8 64.5 Carbon disulphide .................. 35.4 32.9 Benzene ............................. 2.4 2.8 Total .......................... 99% 100 -2 - Volume of gas taken ............... 100 100 possibility still remained that the absence of reaction was by a film of sulphide protecting the sodium. In the next experiments, the liquid alloy of sodium and potassium was substituted for pure sodiuw, and the vessel continually, but gently, shaken to expose a fresh surface t o the action of the carbon disulphide. As in previous experiments, however, the gas obtained was simply a mixture of carbon dioxide and carbon disulphide with a little benzene, and showed no indication whatever of the presence of any other compound.Finally, sodium and carbon disulphide were allowed to react in a sealed apparatus fitted with a mercury gauge. The apparatus is Ggured in the sketch (p. 1542) : A is a tube containing sodium, spread by melt- ing over a considerable surface, and B is a bulb partly filled with carbon disulphide ; C is a mercury gauge. After exhausting the air and sealing off, the apparatus mas allowed to stand for some months at the temperature of the laboratory. The sodium became coated with a red substance, but on bringing the apparatus to the original temperature and pressure, it was found that the mercury stood a t its original level, and there had been no evolution of gas whatsoever.The carbon disulphide was found not to hold any gaseous compound in solution. We think these experiments show fairly conclusively that no gaseous substance is evolved during the reaction of sodium and carbon di- sulphide, and that the gas obtained by Deninger’s method is simply a mixture of hydrogen, carbon disulphide, and hydrogen sulphide.1542 NON-EXISTENCE OF THE GASEOUS SULPHlDE OF CARBON. The other two methods-the reaction between sodium sulphide and chloroform, and that between silver sulphide and iodoform-were not studied in such detail, but here, again, no indication could be obtained of the formation of any new gas. A mixture of potassium sulphide and chloroform was heated in a sealed tube at 180' for some hours : on opening the tube we found hydrogen sulphide, hydrogen chloride, unchanged chloroform, free sulphur, and a reddish-yellow liquid less volatile than chloroform, and having the charaeteristic odour of the alkyl sulphides.Somewhat similar results were obtained when a mixture of silver sulphide and iodoform (5 grams of each), was heated at 180'; the reddish-yellow liquid was obtained in this case also, together with much hydrogen and some carbon disulphide. The gas obtained had an extremely unpleasant odour. On explosion with oxygen, about 6 per cent. of sulphur dioxide was formed, accompanied by more than five times that amount of carbon dioxide ; this result is completely explained by the presence of the vapours of carbon di- sulphide and the yellowish-red sulphide, and indicates that in the latter compound there are four or more carbon atoms to each atom of sulphur. We could find no indication of any gas having the formula CS ; we cannot say, of course, that no such gas is present, as the complex nature of the products of the last two methods puts a quan- titative analysis out of the question; but we maintain that all Deninger's results can be completely explained without assuming the existence of any new gas. THE OWENS COLLEGE, MANCHESTER. SOUTH-EASTERN AGRICULTURAL COLLEGE, WYE, KENT.