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XVI.—Note upon the action of heat upon valeric acid; with some remarks upon the formulæ of the alcohol-radicals

 

作者: A. W. Hofmann,  

 

期刊: Quarterly Journal of the Chemical Society of London  (RSC Available online 1851)
卷期: Volume 3, issue 2  

页码: 121-134

 

ISSN:1743-6893

 

年代: 1851

 

DOI:10.1039/QJ8510300121

 

出版商: RSC

 

数据来源: RSC

 

摘要:

DR HOFNANN ON VALERIC ACID. XVX.-Note upon the Action of Heat upon Valeric Acid; with some remarks upon the forrnut~eof the Alcohol-Radicals. By A. W. HOFMANN, Ph.D. F.C.S. The interesting experiments which Capt. Reynolds has just now communicated to the Society have pointed out the existence of a gas long anticipated by theory but which had hitherto escaped observation. This body will most likely be found a very frequent product of the dry distillation of sLzbstances rich in hydrogen. The gases hitherto obtained in various reactions of this kind and con- sidered as olefiant gas may possibly have contained together with the latter some proportions of this hydrocarbon c6 He and it is by no means improbable that the luminiferous properties of common coal gas far from entirely arising from olefiant gas may be partly due to the presence of propylene of butylene and even of amylene.The method used by Capt. Reynolds in treating his gas with bromine might be followed with advantage in order to settle this point. By adopting this plan I have been able to trace the evolution of propylene in a reaction which has lately engaged my attention. The vapour of valeric (valerianic) acid when passed through a red-hot tube yFlds a considerable volume of gas together with a quantity of liquid products the amount of which varies with the temperature at which the action is performed. Without entering into details respecting the liquid products it may at once be stated that the gas consists chiefly of hydrocarbons of the formula C H, together with the oxides of carbon.After having removed the carbonic acid by means of an alkali these hydrocarbons were absorbed by bromine- vapour ;the residuary gas then burned with a blue flame and was found to consist of carbonic oxide. On passing it into pentachloride of antimony it was at once converted into phosgene gas readily recognized by its nauseous odour and by disappearing when con-ducted into water with formation of carbonic and hydrochloric acids. In several operations the gas after having passed successively through potassa bromine pentachloride of antimony and water was no longer inflammable consisting now of accidental atmospheric air ; in other? a mere trace of inflammable gas was left which may have been a member of the marsh-gas family-most likely marsh gas itself; in contact with chlorine it yielded oily drops doubtless of chloride of carbon.On submitting the oily fluid obtained in the absorption of the DB. HOFMANN ON THE ACTION series C 13 to ebullition the thermometer rose at once to 130° C. The main bulk of the liquid passed over between 136O and 156O,when hydrobromic acid wa3 evolved arising from the decomposition of the small quantity of substitution-products the formation of which can never be altogether avoided. On redistilling the resulting liquid the therniometer became tolerably stationary between 143O and 145O when about half of the compound passed over. As I was unable to subject the product which had been prepared on a small scale only to an elaborate purification I could expect from analysis but approximate results.I. 04696 grm. of oil gave 0,3245 ,,,,carbonic acid and 0.1350 ,,,,water. 11. 0*2805 ,,,,oil gave 05276 ,,,,bromide of silver. These numbers lead to the following percentage Carbon ......18934 Hydrogen ..... 3.19 Bromine ......80.00 These numbers although evidently incorrect nevertheless so closely approach the percentage of Capt. Reynolds' hydrobromide of bromide of propionyl that I do not hesitate to assume that the bromine-compound examined actually consisted chiefly of this sub- stance contaminated most likely with a small quantity of a substi-tution-product and possibly of the corresponding terms in the ethylene-and butylene-series.For the sake of comparison I adduce the percentage of these several substances C H Br C H Br C N,Br Carbon ...12.77 17.82 22.22 Hydrogen . . 2.12 2.97 3.70 Bromine ...85.11 79.21 74.08 I ooooo 100~00 100*00 Of the oil distilling at a lower temperature I have only made a bromine- determination. 0.3237 grm. of oil gave 0.6455 , ,,bromide of silver. Percentage of bromine 84-83. This number as well as the boiling-point sufficiently showed that this substance consists chiefly of the bromine-compounds of olefiant gas. OF HEAT ON VALERIC ACID. 123 The chief bulk then of the hydrocarbons evolved in the decom- position of valeric acid by heat would appear to consist of propylene accompanied by small quantities of olefiant gas and possibly of butylene.I could not however affirm the presence of the latter. The experiments of Capt. Reynolds on the action of heat on arnyl-alcohol were made on a sufficiently large scale to prove that in this reaction in addition to propylene no other term of the same series is formed in considerable quantity. I was unable to devote so large a quantity of valeric acid to the attainment of an equal degree of precision and therefore leave it doubtful whether butylene is actually formed in this reaction. The results obtained in the dry distillation of valeric acid were far from what I had anticipated when I undertook the experiment;. 1 had hoped to see this acid imitate the deportment of acetic or benzoic acid under similar circumstances ; these acids being converted with the loss of 2 equivs.of carbonic acid the one into marsh gas the other into benzol. A similar behaviour of valeric acid would have given rise to the formation of a compound c8 H, C,o HI0 0,-2 Cog = c8 HIO. The experiments which I have just now detailed show that the compound in question is not found among the gaseous products of the decomposition of valeric acid. It appears that this term,* unable to exist at the prevailing temperature is broken up into the more stable compounds of the series C H, the excess of hydrogen being eliminated either in the form of marsh gas or as water formed by the reduction of carbonic acid to carbonic oxide. Several experi- ments in which the temperature was so far lowered as to allow a considerable quantity of valeric acid to distil undecomposed yielded sensibly the same results; nor was much difference observed when the tnbes were filled with pumice-stone or when in order to fix the carbonic acid valeric acid was distilled with an excess of baryta.In the latter experiment together with the hydrocarbons C Hn pure hydrogen gas appeared to be evolved. * The members of this series appear to be far less stable than the hydrocarbons con- taining an equal number of carbon- and hydrogen-equivalents. The rapid distillation of margaric acid with and without lime appears to yield hydrocarbons of the family C H only ;this subject however is by no means sufficiently examined. The instabi- lity of these substances would also explain why we have not hitherto obtained a member of the marsh-gas-series derived from the fatty acids in the various tars and naphthas which have been examined whilst the more stable corresponding terms derived by loss of carbonic acid from the acids of the benzoic series viz.benzol toluol xylol cumol cymol have been found to be present in considerable quantities in coal-oil (Mansfield) and in the oil precipitoted from wood-spirit on addition of water (Cahours). 124 DR. HOFMANN It would be interesting to repeat the same experiment with butyric acid and propionic acid; it is possible that the greater simplicity in the construction of the terms C H and C H, will protect them from being broken up into inferior groups. The preparation under the above circumstances of the marsh- gas term of valeric acid acceptable as a contribution towards the completion of this hitherto apparently scanty family would have commanded additional attention by the decision which it appeared to promise of a very important question which is pending at this moment.Chemists have read with unusual interest the highly rcmarkable researches published within the last two years in the Journal of this Society by Drs. Kolbe and Franlrland. Dr Kolbe in his admirable investigation of the products formed in the electrolysis of valeric acid first pointed out the production of a hydrocarbon represented by the formula C H, for which from theoretical views peculiar to himself he proposed the name Vatyt. The above formula represents the radical of the missing alcohol of butyric acid.Kolbe leaves it undecided whether this body actually is the radical in ques- tion but remarks that its vapour-density exactly coincides with this assumption. The next step was the isolation of the radical of a known alcohol of methyl. In treating cyanide of ethyl with potassium Drs. Kolbe and Frankland obtained together with a beautifully crys- talline alkaloid cyanathine isomeric with the mother-compound a permanent gas which exhibited exactly the composition and the condensation of the hypothetical radical methyl The mine being once opened discoverics followed each other with rapidity. Dr. Frankland in pursuing by himself this line of inquiry arrived by acting with zinc upon the alcohol-iodides suc- cessively at the isolation of ethyl c H5 and lastly of amyl c, %I* The details of these beautiful researches performed with remark-able experimental skill are yet fresh in the recollection of the Society.An unusual interest is attached to these investigations; the isolation of the radicals presenting in their compounds so great an ON THE ORGANIC RADICALS. analogy to hydrogen and replacing this element when in a state of mobility both in acids and bases,-the isolation of these elementary groups appeared to be the key-stone of the theoretical edifice in the construction and elaboration of which the finest discoveries of the last twenty years had been made. But notwithstanding the deep interest excited by these discoveries all chemists were not perfectly satisfied with the general character exhibitect by the new radicals.Nobody expected that ethyl like zinc would disengage hydrogen from sulphuric acid and water or that like iron it would precipitate copper or antimony. There were however many who thought whether rightly or wrongly that these substances would under certain circumstances like hydrogen combine directly with chlorine ; that they would combine with other elements without giving rise to phenomena of substitution; and reproduce like other of the isolated radicals as cyanogen or cacodyl some terms of their own series. The great difficulty with which free hydrogen combines with chlorine and the powerful affinity exhibited by the latter element for hydrogeii when in the combined state militates it is true to a certain extent against this assumption; but we have on the other hand in olefiant gas and its congeners well known instances in which this direct combination actually appears to take place.Up to this present moment none of the supposed alcohol-radicals have been observed to combine like cyanogen or cacodyl directly with any of the elements; none of them have been found capable of reproducing a methyl- ethyl- and amyl-compound. The first doubts respecting the interpretation of the experiments in question were raised by some of the French chemists MM. Laurent and Gerhardt,* in reporting upon the investigatioii of Dr. Frankland have pointed out that the bodies described under the names of methyl and ethyl might with more probability be considcred as homologues of marsh gas.In fact if we double the formulze of the substances in question 2 C H = C )I Aeetene. 2 C H = C H, Butene we arrive at a series of substances the analogy of which becomes evident by the following equations C H 0,-2 C02 = (32 H, w w Acetic acd. Marsh gas of acetic acid (Formene). * Compt. Rend. Trav Chim. 1850. 126 DR. HOFMANN Propionic acid. Marsh-gas of propionic acid ( Acetene). Cl HI 0,-2 CO = c H, -J + Valerie acid. Marsh-gas of valeric acid (Bdene). The experiments upon the action of heat on valeric acid which I have communicated to the Society had been undertaken chiefly in order to decide between the two views. If this reaction had given rise to the formation to the body hitherto called ethyl or of a substance having the same compositioii but endowed with different properties we should have been enabled to adopt either the one or the other of these views.Unfortunately this experiment has led to results reconcileable with both opinions the reaction evidently going too far and inferior terms of the family C H being produced. Unable then as I have been to bring forward any experimental evidence of my own in favour of either view I must limit myself to adducing a few considerations in order to raise a discussion of this very important subject which will not decide the question pending but may lead to new experiments and contribute to a more perfect understanding of what is meant by the often somewhat loosely employed term organic radical.If we assume the existence of compound radicals which by their justaposition to chlorine bromine and iodine give rise to the forma- tion of the chlorides &c. of methyl ethyl and amyl we are com- pelled to represent their molecules by 2 volumes of vapour. In this manner the constitution of the vapours of these conipounds becomes perfectly analogous to that of hydrochloric hydrobromic and hydri- odic acids in fact of the compounds of these elements in which the radical is replaced by hydrogen 2 vols of hydrogen + 2 vols. of chlorine = 4 vols. hydrochloric acid. 2 , , ethyl + 2 , , chlorine = 4 , chloride of ethyl. 2 , , amyl -+ 2 , , iodine = 4 , iodide of amyl. The condensation of the vapour of the radical hydrocarbons re-presented as it is by 2 volumes of vapour is very different from that exhibited by ordinary hydrocarbons.The equivalents of these sub- stances have been found to be invariably represented by 4 volumes of vapour. In some cases doubts have been entertained; but it is remarkable that whenever a hydrocarbon has been well studied especially by a careful examination of its metamorphoses the equiva- ON THE ORGANIC RADICALS. lent has been found to correspond to the condensation which I have mentioned. The only hydrocarbon mesitilol the vapour of which appeared to have a different constitution has ceased to form an exception since M. C ahours’ careful density-determination lately communicated to the Society.* The peculiar mode of condensation which we have to assume for the substances called methyl ethyl and aniyl if we consider them as the radicals C H, C H and C, HI1 disappears if we double these formulze.The expressions C €I6 C Hl0 C, H, correspond like all the other hydrocarbons to 4 volumes of vapour. In the absence of any decisive experiments upon the metamorphoses of the substances in question it would be hazardous to adopt the latter formulae in preference to those proposed by Drs. Kolbe and Frankland unless some of the properties of these substances were found to countenance this change. Now I believe that the boiling-points of the eornpounds in question are certainly in favour of formulze representing 4 volumes of vapour.H. Kopp first pointed out the regular differences between the boiling-points of homologous liquids. As an average result from the observations made at the time when he wrote upon this subject he has fixed upon the number 19 as the difference in the boiling temperatures of two analogous substances differing by C H,. The numbers observed are often somewhat lower but frequently also higher benzol (C, H16)boils at 80° toluol (C14H12) at l0S0 the difference being 28O; cumol (Cls HI,) boils at 148O cymol at l75O difference 27O. I readily admit that our knowledge respecting boiling-points is still very deficient ;yet the existence of a regularity like that observed by Kopp for a certain range of the thermometer cannot be denied. Now let us consider the boiling-points of the radicals hitherto observed.Methyl and ethyl being gases at the ordinary temperature may be left out of consideration. Valyl obtained in the electrolysis of vderic acid boils at 108O; amyl as originally produced in the reaction of zinc upon iodide of amyl and lately obtained by Messrs. Gosleth and Brazier in the electric decomposition of caproic acid boils at 155O; and lastly caproyl if we may represent by this term a substance likewise produced by Messrs. Gosleth and Brazier in the analogous decomposition of aenanthylic acid boils at 202O. Name. Formula. Boiling-point. Difference. Valyl . . . cs H 108O 47 Amy1 . . . C,,Hll 155O Caproyl . . . C, N, 2020) 47 * Chem SOC. QII. J. 111 17. 128 DR. HOFMAXN The anomalous differences exhibited by the boiling-points in question amounting actually in these instances for an elementary difference of C H to nearly the double of the niaximuni ever ob- served disappear at once if me adopt formu18 representing 4 volumes of vapour as may be seen from the following conspectus in which the boiling-points of the missing terms are assumed to be half way between those of their neighbours.Name. Formula. Boiling-point. Difference. Valyl . 23 Amy1 . 23 . 23 Caproyl . . 23 I The boiling-points are certainly in favour of the higher formuliR so much indeed that I believe had these substances first been met with in coal-gas naphtha or in the tarry liquids obtained in various processes of distillation few chemists would have adopted other than 4-volume forinulE unless they had been in the possession of additional informa- tion respecting their deportment.The formulze representing 2 volumes of vapour derive in fact their chief support from the re- markable circumstances under which these substances originate. Hydriodic acid and zinc yield iodide of zinc and hydrogen ;in the same manner it would appear the iodide of an alcohol-radical gives rise to the formation of iodide of zinc and the alcohol-radical. There is decidedly a most striking parallelism ;nevertheless there is a certain deficiency in the analogy inasmuch as we do not by the action upon zinc of the hydrogen-acids obtain a compound of zinc and hydrogen corresponding to zinc-methyl.* However nobody will deny that the mode of formation of a compound must always be considered as a most important element in the construction of its formula and in the case before us that mode of formation appears to be certainly in favour of the lower formulae.* The existence of other metallic hydrides as exemplified in the hpdrogen-com- pounds of arsenic and antimony induced me to study the action of dry hydrochloric acid upon zinc exposed in a combustion-tube to the lowest temperature at which the reaction took place ;hydride of zinc if it followed the deportment of zinc-methyl would when coming in contact with water yield hydrogen and protoxide of zinc C If Zn -+ €30= C H4 + Zn 0 EI Zn -+ I10 = H2+ Zn 0 and might in consequence of this decomposition have escaped observation ;hoxerer the gas obtained in the above reaction even when collected in perfectly drg vessels was found to be free from zinc.ON THE ORGAXIi! RADICALS. Nevertheless it would not be difficult to adduce many cases in which an entire reliance upon the mode of formation has led to thc construction of formuh which had subsequently to be rejected when other methods of investigation were applied to the same question. Shortly after the discovery of amyl-alcohol 81. C ahours* examined the action of anhydrous phosphoric acid upon fmel-oil; he obtained a hydrocarbon boiling at 160° which was immediately con- sidered as the olefiant-gas term of the amyl-series C, €Ilo. Nothing appeared siinpler than the formation of this body The density-determination made by the same chemist proved that the hydrocarbon in question was represented by 2 volumes of vapour ; and M.Cahours characteristically remarked at that period that the evident parallelism of the ethyl- and amyl-series was interrupted by the anomaly presented in the condensation of the elements in this hydrocarbon olefiant gas the corresponding term of the ethyl-series being represented by 4 volumes. However only a few years elapsed when &!I. Balard in studying this reaction on a larger scale and using chloride of zinc as an agent of dehydration discovered the actual olefiant-gas term C, Hlo the true amylene boiling at 39O and corresponding like olefiant gas to 4 volumes of vapour. M. Balard showed that C ahours’ hydrocarbon which now assumed the name of paramylene might be represented by c20 H309 (corresponding to 4 vols of vapour) a forinula agreeing perfectly with its boiling-point.The same chemist found that in this reaction in addition even a third member of the same family metamylene c40 H40 is formed the formula of which is likewise represented by 4 volumes of vapour. A series of perfectly analogous remarks applies to the hydrocar- bons derived from acetone by the elimination of water under the influence of sulpharic acid. Mesitilol is far from being represented by the formula which its discoverer assumed who Tvas guided by the supposed analogy of his product with olefiant gas. The boiling- point of the body being far too high for the assumed formula the study of a series of its metamorphoses readily showed that its equivalent is actually treble that represented by the original formula.In the same mannei; I might adduce the change which has been * Ann Ch Phys. [25 LXX 81. To:,* 111.-NO* ‘X B 130 DR IZOFMANN made in the formula of acetone itself,-the original expression of which was doubled in consequence both of its deportment with reagents and its vapour-density. It would not be difficult to quote a great number of cases exhibit- ing in a similar manner the tendency possessed by atoms of inferior order to be polymerized into molecules of a higher equivalent ;and in no group of bodies perhaps does this inclination prevail to a greater extent than among the alcohol-compounds.Hence it would not appear a very unusual mode of decomposition if we assume that under the influence of zinc 2 atoms of the hypo- thetical radical amyl unite to produce the hydrocarbon C, HZ2 This equation in fact would be satisfactory in every respect ;it would be in accordance with the observed deportment of the body with the usual mode of condensation of hydrocarbons with the boiling-point,-and lastly it would be even more in accordance with the formation of the secondary products of decomposition namely of amylene and hydride of amyl. Of the two equations c20 H22 =ClO H12 +c,o HlO 2 GoHI =CIO H12 +ClO HI07 the former is certainly better supported by analogy although I do not lay much stress upon this point The admission of the doubled formule would moreover remove another difficulty the discrepancy exhibited by the boiling-points of amylene hydride of amyl and amyl.Boiling-point. C, Hlo 390 Amylene . Clo H, 155O Any1 Hydride of amyl . C, H,2 30° It appears strange at the first glance that the boiling-point of C, H, should be raised more than looo by the assimilation of 1 equivalent of hydrogen whilst we usually find that the addition of hydrogen depresses the boiling-point; and again that in amyl the boiling-point should be depressed even in a more striking manner by its combining with the same amount of hydrogen. But I do not attach great importance to this point inasmuch as the formukc of these bodies corresponding to different volumes cannot well be compared with each other.nloreover it is but right to state that tye are not very well acquainted with the influence of hydrogen on boiling-points ;thus the boiling-point of bromine is considerably ON THE ORGANIC RADICALS. higher than that of hydrobromic acid whilst on the other hand hydrocyanic acid boils at a higher temperature than cyanogen itself. The metamorphoses of the radicals from which the most decisive evidence in favour of one or the other formula might be obtained have as yet been studied but very imperfectly. The facts however with which we have hitherto become acquainted are by no means in opposition to the higher formuhe. DF. Kolbe believes that the product obtained by distilling vaIy1 with nitric acid contains nitro-butyric acid ; the liquid resulting from the action of nitric acid on am$ presents according to Dr.Frankland a powerful odour of valeric acid. These observa- tions are perfectly in accordance with theory. The respective radicals pass over into the hydrated oxides of amyl and valyl which under the continued influence of the powerful oxidizing agents yield their correlative acids. Admitting that these acids are actually generated-which is still to be proved by more decisive experiments-I think that their formation is perfectly reconcileable with the doubled formulz We know that the action of nitric acid upon oleic acid gives rise to all the acids CnH 0, from capric downwards. We have no difficulty in eon- rerting the higher terms of this series into lower ones e.9,pelargonic acid into caprylic cenanthylic and even caproic acid.There is no reason why the carbohydrides G, H2, or c16 HIS should not yield all the acids containing a smaller iiumber of carbon-equivalents and among these valeric and butyric acids. Cymol and cumol are converted uiider the influence of nitric acid the former C, H, into tohylic acid c, H O, the latter C, HI2 into benzoic-acid c1*H 0,. The- action of chlorine which affords perhaps the simplest method of controlling formulae has been studied as yet only in one individual case. The results which Kolbe and Frankland obtained by acting with chlorine upon methyl derived from the decomposition of cyanide of ethyl with potassium are highly remarkable This gas yields under these circumstances hydrochloric acid and a new chlorinated body represented by the formula C H C1 which coincides with that of chloride of ethyl.The following equations represent the reaction according as we take either the formula C H, or C H,. 2 C H + 2 C1 = C €1 C1 + HC1 c 9-16 + 2 c1 = c H c1 3-H c1. The far greater simplicity of the second equation is evident it has not escaped Mr Frankland dmsuggests that the methyl obtained K2 by the above process is different from the true methyl obtained by acting with zinc upon iodide of methyl or in the electrolysis of acetic acid with which it wouid be only isomeric. An actual diffe-rence between the two substances is not yet proved by experiment. As the question stands at present two views have been enunciated respecting the bodies obtained by Drs.Kolbe and Frankland. The one view assumes the existence of two groups of bodies one emnbrac- ing the alcohol-radicals and another containing the homologues of marsh-gas the former corresponding to 2 the latter to 4 volumes of vapour. According to this view we haw the fdlowing series Metlzj-1 c H Forinene C H Ethyl c* H5 Acetene C H Pro]$* C6 H c H* Valpl (Butyl) C €1 C f40 Amyl c, III Caproelie Cio H, Caproyl C, HI3 c, Hl The other view considers all these substances as members of the same group as homologues of marsh gas (formene) and arrives at the following series Forniene c2 H4 Acetene c Hii Methyl ? C6 H8 Valerene c HI Ethyl ? Caproene C, HI2 Hydride of Amyl.c, % CI Hl Pelai*geae CI6 HIS Valyl ? c, H*0 Caprene C,o H, Amyl? c, H, Laurene c, H26 Caproyl ? In the preceding pages I have pointed out that the boiling-points of the radicals appear to me to speak for formuh with 4 volumes of va-pour; it now remains to be seen whether other experiments will come to the assistance of this view I an? howevei; by no nieans prepared to say whether as represented in the second table the so called radicals are actually bodies of the same properties as marsh gas; that they * This name might be &en to the hydrocarbon obtained by Dr. Kolbp in the electrolysis of hntyric acid ; its urnination is not 1et completed. ON THE ORGANIC RADICALS are homologues of that body as is assumed in &11Srl[.Laurent and Gerh ar d t ’s interesting suggestion.If we bear in mind the endless isomerisms prevailing in the department of organic chemistry and especially among the hydro- carbons witness the large family CZ0 H16 we may perhaps assume that the so-called radicals although presenting the same state of condensation are only isomeric with the homologues of niarsh gas that they may exhibit an isomerism similar to that of cumol and mesitilol. The latter view receives some support from the fact that methyl (acetene) when treated with chlorine yields not chloride of ethyl but a compound isomeric with it whereas if viewed as an homologue of marsh gas it might be expected to give rise to the production of the former. This importaiit experiment should be repeated.If the preceding considerations lead us to adopt a view respecting the substances described under the names of methyl ethyl &c. which to a certain extent differs from that of their discoverers if we cannot admit that the bodies in question actually represent the niolecules which as conceii-ed by the electro-chemical theory by the assimilation of 1 equivalent of chlorine bromine iodine &c. give rise to the formation of the corresponding ethers we are far from denying a most intimate relation of these compounds to the alcohols from which they are derived. This relation is sufficiently indicated by their mode of generation. These radicals it would appear stand to the alcohols in a similar position as benzile and stilbene do to the benzoyl-group or as the acetones stand to their mother-acids.All these substances are formed by the fusion of several organic mole- cules which split again under the influence of powerful agents corn- pounds of the original order being reproduced. The benzoyl-type when passing into benzile or stilbene is polymerized into C, H, ?* and C, H12 which under the influence of oxidizing agents again return to the original series oil of bitter almonds and benzoic acid being formed. Similarly by converting acetic acid into acetone we pass into a higher series from which we step down again by acting with oxidizing agents upon the latter compound which is reconverted into acetic acid. In an analogous manner the so-called alcohol-radicals might give rise to the reproduction of the acids belonging to the original alcohols.Should experiment however prove that the so-called alcohol- radicals are actually the homologues of marsh gas as supposed by Messrs. Laurent and Gerhardt these substances although losing the prestige of radicals in the conception of the electro-chemical 134 DRI HOFMANN ON THE ORGANIC RADICALS. theory would certainly not present less interest. Chemists know the remarkable manner in which the researches of Dumas Regnau 1t and Melsens have linked the methyl-series to marsh gas and thc facility with which we pass from marsh gas over to chloride of methyl. We have a right to expect that the higher hornologues of marsh gas will exhibit a similar deportment.If this be actually the case the action of chlorine upon ethyl would place the whole series of the butylic alcohol at our disposal; in fact we should have discovered a general method of forming the homologues of common alcohol and this series presenting as yet so many gaps would ere long be as complete as the parallel group of the fatty acids May 6 1850. THE PRESIDENT in the Chair. J S Brazier Esq. W. F. Doyne Esq. and Henry Deane Esq. were elected Fellows of the Society. The following presents were announced “Transactions of the Royal Scottish Society of hrts Vol. 111. Part IV :” from the Society. ‘(The Pharmaceutical Journal for April :” from the Editor. C‘Baunian’sMedical Chemistry :” from the ,4uthor “The Quarterly Journal of the Geological Society for May 1850 :” from the Society.A Paper by Professor Vi’ohler was read “On the Nitride of Boron.” See p. 167. May 14 1850. ROBEET PORRETT, EsQ. Treasurer in the Chair. The following presents were announced “An Account of certain Chemical and Microscopical Researches on the Blood Excretions and Breath in Cholera,” by Thorntou J. Herapath Esq. from the Author. I‘The Collected Works of Sir Hurnphry Davy :” from Dr A. TV. ?Vi 11i a m son, ‘‘ The Pharmaceutical Journal for May :” froni the Editor. The following Papers were read

 

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