MR. GRAHAM ON ETHERIFICATION. Feb. 4 1850. WILLIAMALLENMILLER,MI). V.P. in the Chair. Mr. George ,Made was elected a Fellow of the Society. The following Preseiits were announced c‘ The Pharmaceutical Journal,” for February from the Editor. “ Proceedings of the Philosophical Society of Glasgow,” Vol. 111 No. 1. “ Experimental Investigation into the amount of water given off by Plants during their growth,” and ‘(On Agricultural Chemistry,” by J. B. Lawes presented by J. H. Gilbert Ph. D. ‘‘ Address delivered at the Anniversary Meeting of the Geological Society oi’ London on the 16th of February 1849 by Sir Henry T. De la Beche C.B. F.R.S.,” presented by the Author. “ On Benzole,” by C. B. Mansfield from the Author. The following Papers were read “ On some of the Salts of Carbonic Acid,” by Mr.N. Samuelson. VI.-Observations on EtheriJcaiion. By THOMAS GRAHAM,F.R.S. F.C.S. &c. In the ordinary process of etherizing alcohol by distilling that liquid with sulphuric acid two distinct chemical changes are usually recognized ; namely first the formation of sulphovinic acid the double sulphate of ether and watcr ; and secondly the decomposition of the compound named and liberation of ether. The last step or actual separation of the ether is referred to its evaporation in the circumstances of the experiment into an atmosphere of steam and alcohol vapour assisted by the substitution of water as a base to the sulphuric acid in the place of ether. The observation however of M. Liebig that ether is not brought off by a current of air passing through the heated mixture of sulphuric acid and alcohol is subver- sive of the last explanation as it deuionstrates that the physical agency of evaporation is insufficient to separate ether.Induced to try whether ether could not be formed without distillation I obtained results which appear to modify considerably the views which can be taken of the nature of the etherizing process. The spirits of wine or alcohol always employed in the following experiments was of density 0.841 or contained 83 per cent of absolute alcohol. Ezpt. 1. One volume of oil of vitriol was added to four volumes of alcohol in a gradual manner 50 as to prevent aiiy considerable rise MR. GRAHABI ON ETHERIFICATION.of temperature. The mixturc was sealed up in a glass tube 1 inch in diameter and 6.6 inches in length of which the liquid occupied 5.2 inches a space of 1.4 inch being left vacant to provide for expansion of the liquid by heat. The tube was placed in a stout digester containing water and safely exposed to a temperature ranging from 284O to 352O (140O to l78O C.) for one hour. No charring occurred but the liquid measured on cooling 5.25 inches in the tube and divided into two columns the upper occupy- ing 1.75 inches and the lower 3-5 inches of the tube. The former was perfectly transparent and colour1ess and on opening the tube was found to be eiher so entirely free from sulphurous acid that it did not affect the ycllow colour of a drop of' the soluiion of bichro-mate of potash.The lower fluid had a slight yellow tint but was transparent. It contained some ether but was principally a mixture of alcohol water and sulphuric. acid. The salt formed by neutralizing this acid fluid with carbonate of soda did not blacken when heated from which we may infer that little or no sulphovinic acid was present. The principal points to be observed in this experiment are its entire success as an etherizing process without distillation without sensible formation of sulphovinic acid and with a large proportion of alcohol in contact wilh the acid namely iwo equivalents of the former nearly to one of the latter. When the proportion of the alcohol was diminished the results were not so favourable. Expt. 2.A mixture of one volume of oil of vitriol and two volumes of alcohol sealed up in a glass tube was heated in the same manner as the last. The liquid afterwards appeared of an earthy-brown colour by reflected light and was transparent and red by transmitted light. Only a film of ether was sensible after twenty-four hours floating upon the surface of. the dark fluid. Expf.3. With a still smaller proportion of alcohol namely one volume of oil of vitriol with one volume of alcohol which approaches the proportions of the ordinary etherizing process a black opaque liquid was formed at the high teniperature thick and gummy without a perceptible stratum of ether after standing in a cool state. Crystals of bisulphate of soda containing a slight excess of acid were found to etherize about twice their volume of alcohol in a sealed tube quite as effectually as the first proportion of oil of vitriol when heated to the same tempetature.The two liquids found in the tube were colourless no sulphurous acid appeared and only a niinute quantity of sulphovinic acid. Crystals of bisufphate of soda which were formed in an aqueous solution and without an MR. GRAHAM ON ETHERIFICATION. excess of acid had still a sensible but much inferior etherizing power. Expt. 4. A mixture was made of oil of vitriol with a still larger proportion of alcohol namely 1volume of the former and 8 of the latter or nearly 1 equivalent of acid to 4 equivalents of alcohol This mixture was sealed up in a tube and heated for an hour between 284O and 317O (140"and 158O C.) which appeared sufficient for etheriz-ingit.A second exposure for another hour to the same temperature did not sensibly increase the ether product. The column of ether measured 1.25 in the tube and the acid fluid below 2.5 inches. Both fluids were perfectly colourless. It thus appears to be unnecessary to exceed the temperature of 317O (158O C.) in this mode of etherizing and that the proportion of alcohol may be increased to eight times the volume of the oil of vitriol without disadvantage. Expt. 5. The proportions of the first experiment were again used namely 1 volume of oil of vitriol with 4 volumes of alcohol and the mixture heated as in the last experiment to 317O (158O C.) The upper fluid or ether measured 1.1 inch in the tube the lower fluid 2.65 inches.The latter had a slight yellow tint like nitrcus ether but only just perceptible. It gave when neutralized by chalk Sulphate of lime . . 83.11 grains Sulphovinate of lime . . 4.91 , The last salt was soluble in alcohol and crystallized in thin plates. Here again the formation of sulphovinic acid in a successful etherizing prccess is quite insignificant. New results at 317O from the other proportions of 1 volume of oil of vitriol with 1 and 2 volumes of alcohol were quite similar to those obtained in experiments 2 and 3 at the higher temperature of 352O. In none of these experiments did there appear to be any formation of olefiant gas and the tubes could always be opened when cool without danger.Neither glacial phosphoric acid nor crystallized biphosphate of soda etherized alcohol to the slightest degree when heated with that substance in a sealed tube to 360° (182O C.). Even chloride of zinc produced no more at the same temperature than a trace of ether perceptible to the sense of smell. Expt. 6. To illustrate the ordinary process of ether-making a mixture was prepared as usually directed of 100 parts of oil of vitriol 48 , of alcohol (0.841) 18.5 , of water. MR. GRAHAM ON ETHERIFICATION. This liqyid was sealed up in a glass tube and heated to 290' (143O C.) for one hour. It became of a dark greenish-brown colour and opalescent with a gummy looking matter in small quantity. No stratum of ether formed upon the surface of the fluid.The tube was opened and the fluid divided into two equalportions. One of the portions was mixed with half its volume of water and the other with half its volume of alcohol and both sealed up in glass tubes and exposed again to 290° for one hour. It would be expected on the ordinary view of water setting free ether from sulphovinic acid that much ether would be liberated in the mixture above to which water was added. The ether which separated however amounted only to a tshin film after the liquid had stood for several days. In the other liquid on the contrary to which alcohol was added the formation of ether was considerable a column of that liquid appearing which somewhat exceeded balf the original volume of the alcohol added.In fact the srdphovinic acid was nearly incapable of itself of yielding ether even when treated with water. But it was capable of etherizing alcohol added to it in the second mixture like bisulphate of soda or any other acid salt of sulphuric acid. The conclusions which I would venture to draw from these experi- ments are the following. The most direct and normal process for preparing ether appears to be to expose a mixture of oil of vitriol with from four to eight times its volume of alcohol of 83 per cent to a temperature of 320° (160O C.) for a short time. Owing to the volatility of the alcohol this must be done under pressure as in the sealed glass tube. The sulphuric acid then appears to exert an action upon the alcohol to be compared with that which the same acid exhibits when mixed in a small proportion with the essential oils.Oil of turpen-tine mixed with one-twentieth of its volume of sulphuric acid undergoes an entire change being chiefly converted into a mixture of two other hydrocarbons terebene and colophene one of which has a much higher boiling point and greater vapour-density than the oils of turpentine. This hydrocarbon does not combine with the acid but is merely increased in atomic weight and gaseous density without any further derangement of composition by a remarkable polymeriz- ing action (as it may be termed) of the sulphuric acid. So of the hydrocarbon of alcohol; its density is doubled in ether by the same polymerizing action. Chloride of zinc effects with alcohol at an elevated temperature a polymeric catalysis of the latter of the same MR.GRAHAM ON ETHERIFICATION. character but in which hydrocarbons are formed of even greater density and free from oxygen. This view of etherification is only to be considered as an expression of the coutact-theory of that process which has long been so ably advocated by 31.Mitscherlich. The formation of sulphovinic acid appears not to be a necessary step in the production of ether ;for we have found that the etheriz- ing proceeded most advantageously with bisulphate of soda or with sulphuric arid mixed with a 1arg.e proportion of alcohol and water which would greatly impede the production of sulphovinic acid. It appears indeed thai the Combination of alcohol with sulphuric acid in the form of sulphovinic acid greatly diminishes the chance of the former being afterwards etherized; for when the proportion of oil of vitriol was increased in the preceding experiments which would give much sulphovinic acid the formation of ether rapidly diminished.The previous conversion of alcohol into sulphovinic acid appears therefore to be actually prejudicial and to stand in the way of its subsequent transformation into ether. The operation of etherizing has attained a kind of technical perfec- tion in the beautiful continuous process now followed. The first mix- ture of alcohol and sulphuric acid is converted into sulphovinic acid the sulphate of ether and water which acid salt appears to be the agent which polymerizes all the alcohol afterwards introduced into fluid.Bisulphate of soda with a slight excess of acid acts upon alcohol in the same manner and its substitution for the acid sulphate of ether would have a certain interest in a theoretical paint of view although a change of no practical importance in the preparation of ether. Sulphuric acid does not appear to be adapted for the etherizing of amylic alcohol. M. Balard by distilling these substances together obtained a variety of hydrocarbons some of them of great density but no ether. The polymerizing action of the sulphuric acid appears to advance beyond the ether stage I have varied the experiment by heating amylic alcohol in a close tube to 350° (176O C.) with oil of vitriol to which 1 2 3 4 and even 6 equivalents of water had been added without obtaining anything but the hydrocarbons of Balard. The formation of these was abundant even with the most highly hydrated acid and with a very moderate colouration of the fluid.