28 V.-Research on Acids of t7te Lactic Series.-No. 1. Synthesis of Acids of the Lactic Series By E. FRANKLAND, F.R.S. Professor of Chemistry in the Goveinment School of Mines; and B. F. DUPPA,Esq. F.R.S (Fromthe Philoaophical Tramactions for 1866,) WITHthe exception of the acetic series no family of organic acids has excited so much interest amongst chemists and been the subject of such numerous researches as that represented by lactic acid. Its character intermediate between the mono- basic and bibasic acids its close relations to the acetic and acrylic families and the numerous important transformations which it undergoes have all contributed to render this family an attractive subject for experimental inquiry and a fruitful source of theoretical speculation.These inquiries and hypo- theses have contributed greatly to the elucidation of thc habits of these acids and still more to the general progress of organic chemistry. Nevertheless there are two circumstances which have materially interfered with their complete success ; t.hese are the comparat,ively small number of the known members of this series and the absence of any synthetical proof of the nature of their constituent radicals. These obstacles to a more satisfactory conception of the internal architecture of the acids in question we have eddeavoured to remove by the production according to purely synthetical methods of a number of new members of this series a brief notice of which we have from time to time had the honour of submitting to the Royal Society,' and the more complete history of which we propose to de-velop in the following pages.Our general method for syn- thetically producing the acids of the lactic series depends upon the replacement of one of the atoms of dyad oxygen in oxalic acid or rather in the ethereal salts of oxalic acid,.by two semi- molecules of monad alcohol radicals. Such a replacement at once transforms bibasic oxalic acid into a monobasic acid of the lactic series. The nature of this transformjition as well as * Proceedings of the Rojal Society pol. xii p. 396; pol. xiii p. 140; vol. xiv pp. 17 79 83 191 197 and 198 FRhNRILhhD AND DUPPA'S RESEARCHES ETC. the relations of oxalic acid to the lactic family is clearly seen from t,he following comparison of the formule of oxalic acid and of its derivative diinethoxalic acid :-This snbstitution of :dcohol-radicals for one atom of oxygeii in oxalic acid can be readily effected by act,ing upoil the ethereal salts of oxalic a,cid by the zinc-compounds of the alcohol- radicals.In this reaction ethylic oxalatci was mixed with rather more than its own volume of pure zincethyl ; the temperature of the mixture gradually rose and large quantities of gas were evolred consisting of about equal volumes of ethylic hydiide and * In this paper 0 = 16 C = 12 H = 1 Zn = 65 Ba = 137 Cu = 635; Ho = (OH) the monad radical hjdroxyl or peroxide of hydrogen ; Eto = (OCpHj) ethoxyl or peroxide of ethyl &c. + As large quantities of ethylic oxalate were required for this and the following reactions it became a matter of imporlance to prepare this compound in the most economical manner.After trying the numerous met.hods which have been recom- mended we found the following process to give the laygat product :-1,500 grammes of oxalic acid thoroughly dried at 100" C. are placed together with 1,000 grammes of absolute methylated spirit in a capacious retort which is thcn very slowly heated by an oil-bath to 100"C.,at which temperatuie water begins to distil over; when the thermometer has risen to 105" a steady stream of absolute methylated spirit is couducted to the bottom of the retort at the rate of about 80 grammes per hour the temperature being allowed to rise very slowly to 125"-130" C. Care Being taken on the one hand tbat alcohol shall not distil over in which case the temperature should be raised and on the other that the heat be not 80 great a.9 to cause the generation of gas.At this rate it requires about twelve hours to make the addition of 1,000 grammes of alcohol; after which the retort must be gradually heated to the boiling-point of ethylic oxalate and the remainder of the distillate which is the pure oxalic ether collected apart. By fractional distillation the first portions afford a considerable additional quantity of the pure product besides ethylic formate. During the final operation in consequence of the presence of some uncon-verted oxalic acid B quantity of gas is always evolved ; nevertheless in frequently repeated operations we have obtained an ainount of pure ethylic oxalate equal in weight to the dried oxalic acid employed.FRANKLAND AND DUPPA'S RESEARCHES ethylene and resulting from the decomposition of ethyl ac-cording to the following equation :-Ethyl. Ethylic hpnride. Ethylene. For the attainment of the desired result of the reaction it is best to prevent thia secondary decomposition as much as possible. This we succeeded in doing by preventing the tem- perature from rising beyond 60" or 70" C. until the operatioil wa8 considerably advanced. Afterwards it wits necessary to heat to 100"C. to complete the reaction. The mixture generally continues fluid but asmmes a light straw-dour and a thick oily consistency. On heating it to 130"C. in a retort no distillate passes over.If after cooling its own volume of water be very gradually added torrents of ethylic hydride are evolved and on subsequent distillation in a water-bath weak alcohol containing an ethereal oil in solution passes over; a further quantity of the oil may be obtained by adding water to the residue in the retort and contiiming the distillation on a sand-bath. By repeated rectification the alcohol can be approximately separated from the .water and oil whilst the latter may then be removed by a separator. The oily product so obtained was submitted to rectification when its boiling point rapidly rose to 175" at which tempera- ture the whole of the remaining and very large proportion of the liquid distilled over. The analysis of this liquid yielded numbera agreeing with the formula- C,H,,O,* We shall prove below that this body is the ethylic ether of an acid possessing the same composition as the leucic acid obtained by Strecker* in acting on leucine with nitrous acid.The two acids are probably isomeric; and we therefore prefer to call the one prepared synthetically dietlioxalic acid and the ether above analysed etliylic diethoxalate. The formation of ethylic diethoxalate is explained in the following equatioiis :-Ethylic oxalate. Zincethyl. Ethylic zincmonethyl Eincetbylo-diethoxalde. ethylate. f Ann Ch. Pharm. lxviii 54. ON ACIDS OF THE LACTIC SERIES. (COEto + CEt,(OZn"Et) 2H20 = -{EEb,",o + Zn"Ho + EtH. Ethylic zincmonethyl Ethylic Zincic Ethylic die thoxalate.diethoxalate. hydrate. hydride. The first of these equations expresses the action of zincethyl upon ethylic oxalate by which ethylic zincmonethyl diethoxa- late is formed." The second shows the action of water upon this compound by which the zincmonethyl (ZnC,H5) becomes replaced by hydrogen.? Although we have not heen able to isolate the ethylic zincmoiiethyl diethoxalate from the other product of this decomposition yet we have proved its existence by forming it synthetically as described below. Ethylic diethoxalate is a colourless tra,nspareiit and some- what oily liquid possessing a peculiar and penetrating etherea,l odour and a sharp taste. It is insoluble in water but readily soluble in alcohol or ether. Its specific gravity is 09613 at 18'07 C.; it boils at 175" C. and distils unchanged. Two deter-minations of the specific gravity of its vapour gave the numbers 5.241 and 5-23. the number 5.528. We have remarked on this and other similar discrepancies below. When zincethyl is added to ethylic diethoxalate previously cooled in a freezing mixture each drop of the zinc compound as it comes into contact with the ether hisses like phosphoric anhydride when dropped into water. Torrents of ethylic hydride are evolved and the mixture finally solidifies to a white teiiacious mass which melts on the application of heat and does not distil below 100" C. at about which temperature a violent action sets in ; a great quantity of gas is evolved and * This interpretation of the reaction wa~ first proposed by But1 erow (Bull.SOC. Chimique 1864 p. 116); and we have since confirmed it by the synthetical produc- tion of ethylic zincmonethyl diethoxalate as described below. + The final result of tbis reaction is exactly homologous with the production of glycollic acid by the action of nascent hydrogen upon oxalic acid described by Schulze (Ann. Ch. Phys. Ixvii 366) { ggEz + H = { z:hT + H20. Oxalic acid Glycollic acid FRANKLAND AND DUPPA’S RESEARCHES the residue solidifies to a pitch-like mass which 011 treatment with water and subsequent distillation yields about one-fourth of the ethylic diethoxnlste employed. If the above-mentioued white mass instead of being heated be mixed with water it effervesces strongly zincic hydrate is foimed and pure ethylic diethoxalate separates in quantity nearly equal to that origin- ally employed.In a quantitative experiment 12.93 grms. of zincethyl were treated with ethylic diethoxalate excess being avoided ; 15.67 grms. of ethylic diethoxalate were required to saturate t’he above quantity of zincethyl and the weight of ethylic hydride evolved which was carefully determined amounted to 3-08 grms. These numbers agree closely with those deduced from the following equation :-Ethylic Ethylic zincmonethyl diethoxalate. die thoxalate. Et7tylic xincmoneth,yl dietlmsakrte is a colourless viscous solid aoluMe in ether but apparently incapable of crystallisation. It absorbs oxygen with avidity and in contact with water effervesces strongly reproducing ethylic diethoxalate according to the following equation :--rcoQo + 2H,O -CEt Ho + EtII + Zn”HoZ’ \ Ethylic zincmonethyl Ettiylic die thoxalate.diethoxalate. Ethylic zincrnonethyl diethoxalate combines energetically with iodine; an ethereal solution of the latter added to it is almost instantly decolorized and a large quantity of et.hylic iodide is produced. 14 2 { gyp’/E9 + = {:‘t’zn// + Zn”I + 2Et1 Ethylic zincmonethyl {:%it diethoxalate. Ethylic zincodiethoxarate. It was obviously impossible to collect in a state of purity the ethylic iodide thus set at liberty without considerable losls ; ON ACIDS OF THE LACTIC SERIES. but the quantity of the pure iodide actually obtained warS 12 grms.The above equation requires 14.6 ems. On the removal of ether and ethylic iodide the mixture of ethylic zhcodiethoxalate and zincic iodide forms a transparent gummy mass easily soluble in ether carbonic disulphide or caoutchoucin but totally incapable of crystallising from any of itps solutions. All our attempts to separate these bodies have hitherto proved abortive; and it is by no means improbable that they are chemically combined. The existence of monad orgauo-zinc radicals such as zinc-monethyl receives further support from the slow action of oxygen upon zincethyl which clearly shows that there are two distinct stages in the process of oxidation. These stages have indeed already been indicat,ed by one of us in describing the reactions of this body." When a current of dry oxygen is made to pass through an ethereal solution of zincethyl dense white fumes continue to fill the atmosphere of the vessel until about one-half of the total qimntity of oxygen necessary for the com- plete oxidation of the zincethyl has been taken up.Then the white fumes entirely cease showing the absence of free zinc- ethyl and at the same moment the liquid which up to that time had remained perfectly transparent begins to deposit a copious white precipitate and the latter continues to increase until the remaining half of the oxygenis absorbed. If the pro- cess of oxidation be arrested when the white fumes cease to be formed the product effervesces violently when mixed with water owing to the escape of ethylic hydride; but when the oxidation is completed the white solid masbr produced consists chiefly of zincethylate and does not in the slightest degree effervesce in contact with water.The two stages of this reaction depend essentially upon the mccessive linking of the zinc with the two atoms of ethyl by means of dyad oxygen. The first stage of oxidation is expressed by the following equation :-Zn"Et, + 0 = Zn"EtEto. Zincethyl. Zincethylo-ethylate. The zincethylo-ethylate thus formed is perfectly soluble in ether and is instanIly decomposed by water according to the following equation :-* PhiIoaophical Transactions 1856,p. 258. VOL. XXII. D FRANKLAND AND DUPPA’S RESEARCHES Zn’TtEto + 2H,O = Zn”Ho -/-FlO + El0 Zincethjlo-ethyhte.Zincic Alcohol. Ethilic hydrate. hydride. Treated with dry oxygen zincethylo-ethylate in ethereal solution absorbs a second atom of that element; and it iR this further a.bsorption that constitutes the second stage above referred to resulting in the production of ziiicic ethylate Zn”EtEto + 0 = Zn”Eto,. Wanlrlyn” was the first clearly to point out the probable existence of zincmonethyl or rather its homologue zincmono- methyl indicating at the same time its radical function when he ascribed to the crystalline compound obtained in the preparation of zincmethyl the formula Zn,IMe.j. In the same memoir he also represented this compound as the analogue of mercuric methiodide Bu tlerowz has also prominently drawn attention to this behaviour of organic zinc-compounds and has succeeded in obtaining zincmethylo-methylate Zn”MeMeo in a condition approaching to purity by passing a stream of dry air through a solution of zincmethyl in rnethylic iodide.Butlerow’s success in obtaining this body and his failure in converting it into zincmethylate are both probably due to the comparative insolubility of zincmethylo-methylate in methylic iodide owing to which the first product of oxidation was to a great extent protected from the further action of oxygen. When however ether is used as the solvent in the case of zinc- ethyl the oxidized product remains in solution t.ill the first fitage is passed after which zinc-ethylate is gra,dually pre-* Journ. Chem. SOC.1861 p.127. 1.Zn = 32.5 in this formula. 5 Bull. SOC.Chimique 1864 p. 116. ON ACIDS OF THX LACTIU SERIES. cipitated until the second stage is completed. Indeed as shown in the memoir above referred to (Philosophical Trans- actions 1855 p. Zt;S) the oxidation instead of stopping at the first stage proceeds even somewhat further than the second and the final product formed does not possess a composition in any degree approaching that which Butlerow asserts it to have. This is evident from the following numbers and from the circumstance that it does not effervesce in the slightest degree when mixed with water :-Percentage composition Percentage composition according to Butlerow’s according to mean of analyses.* c .......... 34-53 25.43 H ..........7-20 5-32 Zn.. ........ 46.76 42-04 0 .......... 11-51 27-21 100.00 100-00 When ethylic diethoxalate is treated with solution of baric hydrate it gradually dissolves even in the cold; on heating the solution in a water-bath a liquid having the properties of alcohol distils off; and on separating the excess of baryta by carbonic anhydride and filtration the salution yields on evaporationa crystallisable salt consisting of baric diethoxalate Baric diethoxalate is veiy soluble even in cold water ; when its boiling solution is precipitated with excess of dilute sulphuric acid and the baric sulphate removed by filtriztioii ether readily extracts diethoxalic acid from the cooled filtrate. On evapo-rating the ethereal solution the acid crystallises in splendid pris~ns,which after drying in vucuo gave results agreeing with the formula Je Philosophical Transactions 1855 p.268. FRANKLAND m DUPPA’S RE~OEES Die&oxalic acid is wry soluble in alcohol or ether and scgnewhat less BO in water. By the spontaneous evaporation of its aqueous solution it crystallises in minute prismatic needles ; but if a small quantity of dilute sulphuiic acid be added to the solntion the crystals are deposited in magnificent anorthic prisms which frequently attain a length of 1inch and a thick-ness of + inch. Diethoxalic add is greasy to the touch like stearic acid; it melts at 74”*5C. and slowly sublimes at the same temperature but is decomposed before reaching its boiling point.It has a Bour taste reddens litmus strongly aud expels carbonic acid from carbonates. It forms an extensive series of salts which are all soluble in water. In addition to the barium-salt described above we have examined the silver copper and zinc salts. Argentic diethoxnlate i8 readily prepared by boiling an aqueoua solution of the acid with excess of argentic carbonate. On filtration and evaporation in vacuo the salt crystallises in biilliant needles radiating from centres standing up freely from the capsule and containing half a molecule of water which is not expelled at 100” C Submitted to analysis this salt gave numbers indicating the forrnula Cup& diethoxnlate is obtained by mixing atomic proportions of bark diethoxalate with cupric sulphate filt.ering and evapo- ratiiig to dryness.The salt does not crystallise but dries down to a green gum-like mass which becomes nearly white on being reduced to powder. Submitted to analysis it yielded results agreeing with the formula &a& diethoaalate crystallises in nacreous scales which are sparingly soluble in water and in alcohol. Two determinations of the solubility of this salt in water at 16”C. gave the following results :-I. One part of the salt dissolved in 291 parts of water. ON ACIDS OF THE LkCTfU iSfiIlCS* 37 11. One part of the salt dissolved in 312 parts of wate Ite solubility in boiling water is not much greater. Although 80 difficultly soluble in pure water it dissolvea very readily in a solution of zincic iodide.The method of producing ethylic diethoxalate above dmcribed involves the previous preparation of considerable quantities of zincethyl but we have found that the process may be much simplified by generating the zincethyl during the reaction which is effected by gently heating a mixture of granulated zinc ethylic iodide and ethylic oxalate for several hours. After long experience in the production of this and other homo- logom compounds described below we have found the following process for the preparation of ethylic diethoxalate to give a maximum product. 600 grammes of a mixture consisting of one molecule of' ethylic oxalate and two of ethylic iodide were placed in a capacious flask with such a quantity of well-dried granulated zinc that the latter rose above the surface of the liquid.An inverted Liebig's condenser was attached to the flask. It ia preferable to use zinc which has been employed in a previous operation as it not only acts with greater rapidity but also at it much lower temperature. The flask was immersed in water maintained at a temperature of about 30" C. After a period of time which varies in each operation but is usually from twelve to twenty-four hours an energetic action sets in which must be checked by lowering the temperature of the water- bath. The reaction once commenced is usually completed in from twelve to eighteen hours the temperature of the water- bath being maintained at about 30" C. until it is nearly con- cluded when it may be raised to 100" C.The operation may be regarded as complete when the hot liquid assumes the con- sistency of honey and solidifies to a more or less crystalline mass on cooling although a considerable quantity of the mixed ethers is still unacted upon. Water being now gradually added until it equals three times the volume of the crystalline mass with which it must be well mixed by agitation a copious effervescence takes place ; zincic oxalate and oxide are formed in abundance whilst on the application of the heat of an oil- bath alcohol accompanied by ethylic diethoxalate distils over together with the ethylic iodide that has not been acted upon. This distillate is then treated in exactly the same manner aa 38 FR-D AM) DUF’PA’S RESEARCHES that already described for the separation and purification of sthyl-ic dietboxalate prepared by means of zincethyl.In the operation abow mentioned with 600 grammes of the mixed ethylic iodide and oxalate 86 grammes of pure ethylic dieth- oxalate were obtained the theoretical amount being 105 grammes. 11. Action of Zinc tpon a Mixture of Methylie Iodide and iMethylic Oxalute. Two molecules of methylic iodide were mixed with one mole- cule of niethglic oxalate and placed in contact with an excess of granulated zinc at 30”C. in a flask as above described. At the eoncluaion of the reaction the liquid solidified to a crystalline mass which on distillation with water yielded methylic alcoliol possessing an ethereal odour but from which no ether could be extracted.The residual magma in the flask consisting of aincic iodide zincic oxalate and the zinc salt of a new acid was separated from the metallic zinc by washing with water. It was then treated with an excesg of baric hydrate and boiled for R considerable time ; carbonic anhydride was afterwards passed through the liquid until on again boiling the excess of barytn was complctely removed. To the filtered solution recently precipitated argentic oxide was added until all iodine was removed. The solution separated from the argentic iodide was again submitted to a current of carbonic anhydride boiled and filtered. The resulting liquid on being evaporated on the water-bath yielded a salt crystallising in brilliant needles and possessing the peculiar odour of fresh butter.This salt is very soluble in water and in alcohol but nearly insoluble in ether and perfectly neutral to test-papers. On being submitted to analysis it gave numbers closely corresponding with the formula Dimethoxulic acid is obtained from its barium-salt by adcling dilute sulph-ruic acid to a concenti-ated eolutiorl of the latter and agitating with ether. 011 allowing the ether to evaporate ON ACIDS OF TRE LACTIC SERIES. spontaneously prismatic crystals of considerable size in ake their appearance. These yielded on combustion readts agreentg with the formula {Ee0 Piniethoxalic acid is a white solid readily crystallisiag in beautifid prisms resembling oxalic acid. It melts at 75O-7 C. volatilizes slowly even at common temperatures and readily sublimes at 50" C.being deposited on a cool surface in mag- nificent prisms. It boils at about 212"C. and distils unchanged. Dimetlioxalic acid reacts strongly acid and unites with bases forming a numerous class of salts several of which are crystal- line. In addition to the barium-salt above mentioned we have examined the silver-salt which is best formed by adding argeiitic oxide t'o the free acid heating to boiling and filtering when the salt is deposited in starlike masses of nacreous scales as the solution cools. On analysis this salt gave numbers closely corresponding with those calculated from the formula Attempts to prDduce ethylic dimethoxalate by digesting t-he free acid with absolute alcohol at a temperature of IGO" C.proved abortive traces only of the ether being apparently formed. Judging however from our subsequciit success in obtaining ethylic dimethoxalate as described below we believe that the methylic ether would probably be obtained by re-peatedly agitating with ether the aqueous &stillate obtained from the crude product of the original operation methplic di- niethoxztlate being evidently like ethylic dimethoxalate miscible with water in all proportions. Assuming the formation .of this ether its production fi-on1 the miztual action of zinc methylic oxalate arid metliylic iodide followed by that of water would be expressed in the following equations :-~~~~~ { + Zn'b + 4MeT = { CAfe'"Zn''Me) + Zn'/MeMeo + 2 Zn''i2 : CUMeo Methylic Methyli.zincmono- Zincmethylo-oxalate. methgl dimethouslate. methglate. Methylic zincmonome thy1 Metbylic Zincic hjdraie. dimetlioxalate. dimethoxalate. FRANgLBND AND DUPPA'S RESEAR4XiES Dimethoxalic acid exhibits the aame composition as Staedeler's acetonic acid Wurtz's butylactic acid and the oxybutyric acid obtained by Friedel and Machuca. The relations of these acids to each other will be discussed at the conclulsion of this paper. 111. Action of Zinc upon a Mixture of Ethylic Iodide and Methylic Oxalate. This reaction was performed in exactly the same manner as the last. On addition of water the product yielded on subsequent dbtillaiim a considerable quantity of an ethereal body which distilled over together with Che ethylic iodide that had not been acted upon.The additio-rl of water to the dis-tillate effected an approximate separation of the ethereal from the alcoholic portion; the former was then decanted and dis-tilled for the purpose of separating alcohol and ethylic iodide. When the temperature of ebullition rase to 100" C. the liquid left in the retort was placed OVZP calcic chloiide for twelve hours after which it was again sabmitted to distillation when its boiling point almost immediately rose to 165" C. (barom. 758.2 millims.) at which temperature the whole of the remain- ing liquid passed over. S~bmittedto analysis this liquid yielded resulk closely corresponding to the formula The decomposition of this e&er by baryta described below proves it to be the methylic ether of an acid of the same corn- position as dieihoxalic acid with which it also agrees in its fusing point.The composition of this ether may therefore be thus expressed (::has Methylic Diethoxalate is a colourless transparent and tolerably mobile liquid possessing a peculiar ethereal odour only re- motely resemblinz that of ethylic diethoxalate. It is very sparhgly soluble in water but readily soluble in alcohol or ether. Its specific gravity is -9896 at 16"-5C. It boils at 165' C. and distils unchanged Its vapour-density was found by experiment to be 4.84. The above formula corresponding to two volumes of vapour requires the number 5.03. ON ACIDS OF THE LACTIC SERIES. Trea,ted with caustic alkaline bases this ether is readily decomposed even in the cold yielding methglic alcohol and a diethoxalate of the base.A quantity of it was thus decom- posed with solution of baryta the excess of base being after- wards removed. It yielded on evaporation a crystalline mass very soluble in water alcohol or ether aid which on analysis gave results corresponding with those calculated from the formula of baric diethoxakute CEt,Ho Loo coO*a"* ICEt,Ho When this barium-salt in aqueous solntion is decomposed with the exact amount of sulphuric acid necessary the liquid filtered off fiom the baric sulphate and evaporated in vacuo the acid crystallises magnificently. Professor W. Hall ow s Miller of Cambridge has kindly examined and measured these crystals for us with the following results :-Anorthic :-100 110 = 66" 2'; 110 010 = 34" 15'; 100,001 = 76' 40'; 001 ioi = 29" 4'; 010,ooi = 75O 13'.Observed forms :-100 010 001 110,iio ioi Foi. Angles. 010,001 001 oio 75 13 104 47 100 001- 76 40 100 001 100 ioi Too ioi 103 20 105 44 74 16 100,201 loo 301 128 41 51 19 001,To1- 29 4 101,201 22 56 100 010 ioo 010 100 17 79 43 VOL. XXII. E FRANRLAND AND DUPPA'S RESEARCHES Angles. 100,110 66 2 010 110 34 15 010 iio 28 36 100,110 51 7 010 ioi 70 0 010) 201 69 31 110,001 68 19 -110 $01 91 52 110,001 84 50 iio ioi 66 16 iio 201 54 30 Combinations :-100,010,001,110 100 010 061 ioi loo 010 001,110,ioi 100 010 001 no Ti0 100 010 001 110,ioi $01 100 010 001,110,ioi iio 100 010 001 110,31,iio 201.Cleavage :-100 010 very perfect and easiIy obtained. The optic axes seen in air through the faces of the form 010 appear to mttke with one another an angle of about 71". De-noting by a b the extremities of radii of the sphere of pro-jection drawn parallel to the directions of the optic axes seen in air through the faces of the form 010 the arcs joining u,,tl and the nearest polea of faces are approximately as follows :- ON ACIDS OF THE LACTIC SERIES. This acid is readily soluble in ether alcohol and water ; it is greasy to the touch and nearly inodorous. It sublimes readily at 50' C. and slowly even at common temperatures a small quantity of the acid left on a watch-glass gradually disappear- ing though in other respects it is permanent when exposed to the air.It hses at 74'05 C. Submitted to analysis it gave numbers agreeing with the formula Argeiitic diethoxalate was made by adding argentic oxide to a hot solution of the acid. After filtration and evaporation in vacuo it crystallises in brilliant silky fibres adhering closely to the capsule. These are anhydrous and are scarcely discoloured by prolonged exposure to -a temperature of l00OC. They yielded on analysis numbers closely corresponding with those calculated from the formula CsH 1AgO3 Although the diethoxalic acid obtained by the action of zincethyl upon -methylic oxalate possesseR the same molecular weight and fusing-point as that prepared by the action of zincethpl upon ethylic oxalate yet the two acids do not appear to be identical.The silver-salt of the latter crystallises as above described (page 36) in brilliant needles radiating from centres standing. freely up from the capsule and containing half a molecule of wa.ter which is not expelled at 100" C. This salt also further differs from that just described by being rapidly discoloured when exposed to the heat of a steam-bath. In a future communication we hope to be able to throw additional light upon this apparent isomerism. IV. Action of Zinc upon a Mixture of EthyEic Iodide Methylie Iodide and Ethylic Oxalate. Having proved in the foregoing reactions the possibility of replacing one atom of oxygen in ethylic oxalate by two semi- molecules of either methyl or ethyl we thought it desirable to ascertain whether the same replacement could be effected by a L2 FRANKLAND AND DUPPA’S RESEARCHES semi-molecule of each of two different monad alcohol-radicals.We endeavoured to accomplish this by acting with zinc upon a mixture consisting of one molecule of ethylic oxalate and one niolecule each of the methylic and ethylic iodides by which we hoped to obtain an acid of‘ the following composition :-Experiment completely proved the practicability of this reac-tion; and its result even exceeded our expectations since not only was the ether corresponding to the above acid formed with the greatest facility but it was produced almost to the complete exclusion of the ethers of diethoxalic and diemeth- oxalic acids.200 grammes of ethylic oxalate were mixed with the proper atomic proportions of methylic iodide and ethylic iodide and were digested with granulated zinc for several days at a tem- perature of from 35O to 40’ C. until the supernatant liquid became oily and solidified to a crystalline mass on cooling. Water being now added till effervescence ceased the whole was submitted to distillation in an oil-bath. With the exception of a small quantity of the mixed ethylic and methylic iodides that had escaped decomposition the distillate consisted of a homo- genous liquid composed of water ethylic and methylic alcohols and an ethereal body which last was separated by repeated agitation with large volumes of ether and subsequent rectifica- tion.In this manner there was obtained a large quantity of a liquid which boiled constantly at 165O.5 C and yielded on analysis numbers very closely corresponding with the formula The production of this ether is explained in the following equations :-{ gEEi + 4Zn + SEtI + 2MeI = { ~~~~(oZn”Me) + Zn’EtEto + 2Zn”12; Ethylic EthyIic zincmonomethyl oxatlate. e thomethoxalate.. {CEtMe(OZn”Me) + 20-4 = (COEto CEtMeHo + MeH + Zn”Ho,. LCQEto Ethylic zincmonome thy1 Eihylic ethometh-Zincic ethomethoxalate. oxalate. hydrate. ON ACIDS OF THE LACTIC SERIES. A not inconsiderable amount of the ether thus formed in this and in the analogous reactions described above appears tlo be decomposed by the zincic hydrate; at all events an appre- ciable quantity of the zinc-salt of the derived acid is always obtained from the residue left after distillation of the ethereal product.Etliylic ethomethoxalate as we propose to name the new ether is a colourless transparent and mobile liquid possessing a penetrating ethereal odour much resembling t,hat of ethylic diethoxalate. It is very soluble in water alcohol and ether and has a specific gravity of -9768 at 13" C. It boils at 165O.5 C. ; and its vapour-deiisity determined by experiment is 4.98 the theoretical number for a two-volume vapour of the above formula being 5-04. Ethylic ethomethoxalate is readily decomposed even by aqueous solutions of the alkalies and of baryta yielding alcohol and a salt of the base By this means baiic ethomethoxalate was prepared.This salt crystallises from an aqueous solution as a beautiful radiated mass of silky lustre very easily soluble in water. Submitted to analygis it gave results agreeing with the formula By exactly decomposing this salt with dilute sulphuric acid and evaporating the filtrate first in a retort and afterwards in a vacuum ethornethoxalic acid was obtained as a splendid white crystalline mass fusing at 63" C. subliming readily at 100"C. and condensing in magnificent star-like groups upon a cold surface. It boils wit,h decomposition at 190" C. Ethometh-oxalic acid is very readily soluble in ether alcohol or water; small fi-agments of it thrown upon water rotate like camphor whilst dissolving.These solutions react powerfully acid and readily decompose carbonates. The analysis of this acid gave results corresponding with the formula FRANKLAND AND DUPPA'S RESEARCHES Argentic ethomethoxalate was prepared by treating the free acid dissolved in water with argentic carbonate. The salt crystallises in splendid mammillated masses half an inch in diameter which are tolerably soluble in water. It gave on analysis numbers agreeing with the formula V. Action of Zinc upon a Mixture of Am3lic Iodide and EtJbylic Oxalate. When a mixture of equivalent proportions of ethylic oxa-late and amylic iodide is digested with granulated zinc at 70' C. the zinc ia gradually dissolved while much amylic hydride and amylene are given off.The mixture finally assumes a viscous or semisolid condition and when treated with water produces a further quantity of amylic hydride which distils off at a gentle heat. On the subsequent applica- tion of a higher temperature water accompanied by amylic alcohol amylic iodide and an etrhe?l liquid distil over the three latter forming a mixture the s4rtration of which into its component parts presents rather formidable difficulties. After drying with calcic chloride the oily mixture begins to boil at about 132' C.; the product first passing over consists prin-cipally of amylic alcoliol mixed with amylic iodide. Afterwards the thermometer rapidly rises to 200' C. between which tem- perature and 203' C. a considerable section of the remaining liquid which we will call A passes over.There then occurs a further rapid rise of temperature until the thermometer remains stationary between 222' and 226' C. The section collected between these points we will call B. Finally the temperature rises to 260' to 2644 between which points the remaining liquid (C) pJsses over. By repeated hctional dist.illation the larger portion of the section A was obtained at the nearly fixed boiling point of 203' C. This liquid was submitted to analysis and yielded numbers coinciding nearly with the formula C9H1803 which interpreted by further results detailed below resolves itself into ON ACIDS OF THE LACTIC SERIES. The ethereal body with the lowest boiling point produced in this reaction is therefore ethylic am,ylhydrosalate or ethylic oxalate in which one atom of oxygen is replaced by one semi- molecule of amyl and one of hydrogen.This body also stands in very close relation to ethylic lactate ; for if the semi-molecule of methyl in ethylic lactate were replaced by amyl ethylic amylhydroxalate would be produced 6hylic lactate. Ethyl& amylhydroxalate. The two stages in the production of ethylic amylhydroxa- late are explained in the following equations :-Ethylic oxalate. Zincic amylo- ethylate. ~ Ctlg(zn"A~)(OZn"Ay)+ 40 = {~ g$iEHo+ 2Zn"Hoa + 2AyH. Ethylic amylhy- Zincic Amylic droxalate. hydrate. hydride. We have not attempted to give a name to the body fiom which ethylic amylhydrosalate is directly produced by the action of water as shown in the last of the foregoing equations The resources of chemical nomenclature already too severely taxed would ecarcely be able to elaborate a constitutional name for this body which consists of ethylic oxalate wherein au atom of oxygen is replaced half by amyl and half by zinc-monamyl whilst a second semi-molecule of zincmonamyl is mbstituted for a semi-molecule of ethyl.Ethylic amylhydroxalate is a somewhat oily transparent and slightly straw-coloured liquid of specific gravity -9449at 13' C. possessing a pleasant aromatic odoiir and burning taste. It boils at 203' C,; and its vapour-density determined by experi-ment is 5.47 the above formula requiring 6.0. To this dis-crepancy me shall refer again presently. Section B of the oily liquid after careful rectification gave a product boiling at 224-225' which yielded on analysis results agreeing with the formula FRANKLAND AND DUPPA’S RESEARCHES The above formula might be interpreted as that of etlb$ic nmylethoxalate the constitutional formula of which would be {%2Ho We were at first inclined to regard this as the actual constitu- tion of the new ether believing it to be possible that ethylic oxalate and am ylic iodide mutually decomposed each other pro-ducing a mixture of amylic and ethylic oxalates with the amylic and ethylic iodides ; an analogous decomposition of mixed ethereal salts of oxygen acids ha@ been recently noticed; but the test of experiment obliged us to abandon this view of the reaction.We found it is true a remarkable depression of temperature amounting to 9’03 C.on mixing one molecule of ethylic oxalate with one of amylic iodide; but on submitting the mixture to distillation the thermometer rose to the boiling point of arnylic iodide (147”)before ebullition commenced thus showing that none of the much more volatile ethylic iodide had been formed. No transfer of radicals therefore takes place when ethylic oxalate is heated with amylic iodide; and conse- quently no zincethyl can be formed when this mixture is acted on by zinc. We therefore prefer to view the ether now under consideration as ethylic ethyl-amylhydroxalate analogous in constitution to W ur t z’s ethylic ethyl-lactate.* (ggyo. {g&;fto. Ethylic ethyl-lactate. Ethylic ethyl-amylhydroxalate.On this view the following equations represent the formation of the ether :-{~~~~~ 1 Znt’J + 4AyI = CA$zn”Y)Eto + Zn’AyAyo + CLZn“1,: COhto Ethylic Amylic Zincic amylo- oxdate. iodide. amylate. CAy(Zn”Ay)Eto + 20H = + Zn”Ho,. {COEto Ethylic ethyl- Amylic Zincic amylhydroxalate. hydride. hydrate. * It deserves to be mentioned that the identity of boiling point between this ether and its isomer amylic diethoxalate described below does not favour this view since 8 eomparison of the boiling points of ethylic ethyllactate with that of ethylic etho- methoxalate and methJlic diethoxalate its isomers shows that the substitution of ethyl for the hydrogen of hydrosyl is attended with a depression of the boiling point equal to 8O.5 C.,the percentage composition of the compound remaining constant.ON ACIDS OF THE LACTIC SERIES. Ethylic ethyl-amylhydroxalate is a straw-coloured oily liquid possessing an aromatic but somewhat amylic odour and a burning taste. Its specific gravity was found to be 09399 at 13"C. It boils between 224' and 225O C A determination of the specific gravity of its vapour by G a y-L u ssa c's method gave the number 6-29 whilst the above formula requires 6.92. Section C of the oily product boiling about 262' C. was next submitted to investigation. It gave on analysis results agreeing approximately with the formula The body is therefore ethylic diamyZoxaZate the normal homo-lope of ethylic diethoxalate as is seen from the following com- parison :-Ethylic diethoxalate.Ethylic diamyloxalate. The production of ethylic diamyloxalate is explained by the following equations :-Ethylic oxalate. Ethylic ziincmonamyl-diamyloxalate. Zincic omylo-ethylate. + 20H2= {COEtoCAY'2Ho+ AyH + Zn"Ho2. diamyhxalate.Ethylic zincmonamgl- diamyloxalate.Ethylic hydride.Amylic hydrate. Zincic Ethylic diarnyloxalate closely resembles the two foregoing ethers in its appearance and properties. It is however a thicker oil and flows less readily and has the lowest specific gravity of any ether belonging to this series ita density at 13" C. being only -9137. The following compaiison of the specific gravities of all the ethers of this series shows that they generally increase inversely as their atomic weights :-Formula.Sp. gr. Temp. 0bserver. Ethylic lactate. . C H,,O 1.042 i3 Wurtz & Friedel. Ethylic dimeth-}C6 H1203 09931 13 F. & D. oxalate . . FRANKLAND AND DUPPA'S RESEARCHES Ethyliclactate ethyl-. . } Formula. 7 143 SP. gr. 0.9203 Temp.0 0 Obeerver. Wurtz. Ethylic etho-methoxalate I)'7 Methylic dieth-oxalate . . H14°3 0.9768 0.9896 13 16.5 F. & D. 97 Ethylic diethox- alate .. 0.9613 18.7 99 Ethylic amylhy- droxalate .. 0.9449 13 ?9 Amylicdiethox-alate .. 11 22 3 0.9322 13 99 0.9399 13 7) alate .. Ethylic diamyl- 0.9137 13 14 98 3 9, oxalate .. Ethylic diamyloxalate boils at about 262O and distils with little or no change. A determination of the specifk gravity of its +apour gave the following numbers :-Weight of ethylic diamyloxalate ..02048p. Observed volume of vapour .. .. 56.78 cub. centh. Temperature of bath .. .. .. 273OC. me Height of barometer . . .. 769millims. Difference of heights of mercury inside and outside tube .. .. .. 70millima. Height of spermaceti column reduced 0. to millims. of mercury. . .. 14millims. From these data the specific gravity 5-9 was deduced whilet the above formula requires 8.4. The investigation of these ethers has revealed a tendency to dissociation increasing with the weight of the semi-molecules replacing the atom of oxygen in ethylic oxalate. Thus beginning with ethylic lactate which has the normal vapour-density we find a gradual divergence culminating in ethylic diamyloxalate as seen in the following series of numbers :- ON ACIDS OF THE LACTIC SERIES.Vapour-densities. Name. Fo~ula.y-/ -\ Observer. Calculated. Found. Ethylic lactate.. C H,,O 4-07 4-14 Wurte & Friedel. F. & D. F.& D. Ethylic ethyl-C,,H,,O 6.92 6-29 99 alate .. methox-} C,,H,,O 6.92 6.74 97 alate .. Ethylic diamyl-5.9 oxalate . . We have likewise prepared the acids corresponding to the three ethers above mentioned. The fist is obtained by decom- posing ethylic amylhydroxalate with baryta treating the solu- tion of the barium-salt thus obtained with excess of sulphuric acid and then dissolving out the organic acid with ether. On evaporating the ethereal solution the acid remains as a thick oil which does not crystallise after several days’ exposure over sulphuric acid in vacuo.The calcium-salt forms a white crys- talline mass soluble in water. Submitted !o analysis *2102ern. gave 00877 grm. calcic sulphate corresponding to 12.27 per cent. of calcium the formula r CAyHHo C14H26Clt”06,or requiring 12.12 per cent. The barium-salt closely resembles that of calcium. -2476grm. gave on analysis 01334 grm. baric sulphate car-responding to 31.68 per cent. of barium. The formula FRANKLAND AND DUPPA’S RESEARCHES CAyHHo CI4H2,Ba“O6,or coo Ba” too CAyHHo requires 32.08 per cent. of barium. We have also obtaiiied a beautifully crystalline acid of the same composition as the above from its zinc-salt contained in the residue remaining after the distillation of the three ethers above described.AmyZl~ydroxa?icacid prepared from this zinc- salt is but sparingly soluble in water fi-om which however it crystallises in magnificent nacreous scales which fuse at 60O.5 C. but afterwards remain liquid for some time even at ordinary temperatures ; they are very unctuous to the touch and readily soluble in alcohol aiid ether. On analysis this acid gave results agreeing well with those calculated from the formula Thebarium-salt of this acid crystallises in large and beautiful nacreous scales like paraffin tolerably soluble in water ; -3765 grm. gave on analysis 02027 grm. baric sulphate corresponding to 31-66 per cent of barium. The formula C,,H,BBa”O, or requires 32.08 per cent. of barium.A copper-salt was also prepared. It is deposited from its aqueous solution in minute light-blue scales very sparingly soluble in water. Submitt,ed to analysis *2341grm. of it gave numbers agreeing closely with the formula fCAvHHo The acid of the second ether ethyLamyl7~ydroxalicacid is pre-pared by the decomposition of ethylic ethyl-amylhydroxalate with alcoholic potash. The acid is afterwards liberated by the ON ACIDS OF THE LACTIC SERIFS. addition of sulphuric acid in excess and may then be dissolved out of the mixture by ether. On the evaporation of the latter the acid remains as a thick oil gradually solidifying to a crys- talline mass which however did not appear to be in a fit state for the determination of its fusing point.The barium- and silver-salts of this acid were prepared. They are both soluble in water ; ,1331 grm. of baric ethyl-amylhydroxalate gave on decomposition with sulphuric acid 00660 grm. baiic sulphate corresponding to 29-15 per cent. of barium the formula ICAyHEto requiring 28.41 per cent. of barium. -1891grm. of argentic ethyl-amylhydroxalate gave on ignition -0722 grm. metallic silver representing 38.18 per cent. The formula requires 38.43 per cent. of silver. The acid of the thirdether (diamyloxalic acid) is best prepared by decomposing the ether with boiling baryta-water. After removing the excess of baryta in the usual manner baric diamyloxalate crystallises on evaporation in minute elastic needles which when dry have the appearance of wool.It is moderately soluble in hot water but sparingly so in cold. Two determinations of barium in this salt gave results agreeing with the formula C24H46Ba’’06, or If baric diamyloxalate be dissolved in hot dilute alcohol and excess of sulphuric acid be added the liquid after filtration contains diamyloxalic acid in solution. On heating upon a water-bath the alcohol gradually evaporates and diamyloxalic acid crystallises in the hot Bolution as a beautiful network of brilliant silky fibres which after being well waahed in cold FRANKLAND AND DUPPA’S RESEARCHES water and dried at loOo,yielded on analysis numbers agreeing well with the formula Diamyloxalic acid presents the appearance of coloiirless satiny fibres which are insoluble in water but soluble in alcohol or ether This acid is remarkable for its high melting point 122O C.in which respect it surpasses any of the acids of this series. Its melting point is very sharply defined and it solidifies immediately on a very slight reduction of temperature. Heated more strongly it sublimes and condenses on a cold sur- face in white crystalline flakes like snow. VI. Action of Zinc upon a Mixture of Ethylic Iodide and Anaylic Oxalate. Equivalent proportions of amylic oxalate and ethylic iodide were digested at 50’ to 60’ with excess of granulated zinc for several days. The reaction proceeded with extreme sluggish- ness and was not completed before the expiration of a week. The mass being then mixed with water and submitted to distil-lation an oily liquid passed over which on rectification was ultimately resolved into amylic alcohol and an ethereal liquid.Submitted to analysis the latter yielded numbers agreeing closely with those calculated from the formula of amylic dieth-oxalate CEt,Ho ‘11’22’39 Or { COAyo The two conswiltjive reactions by which amyIic diethoxalate is produced are expressed in the following equations :-coAYO + Znffq+ 4Etk { gEk$znf’Et) + 2n”EtAyo + SZnI ; (COAyo Amylic Amylic zincmonethyl- Zincethylo-oxalate. diethoxalate. amylate. + 2 OH = + EtH + Znf’Ho2. { g%; Amylic zincmonethy& Amylic dieth-Zincic diethodate. oxalate. hydrate. ON ACIDS OF THE LACTIC SERIES. Amylic diethoxalate is a colourless transparent and slightly oily liquid possessing a fragrant odour of a somewhat amylic character.It is insoluble in water but miscible in all propor- tions with alcohol and ether. Its specific gravity is -93227at 13' C. It boils constantly at 225" C. Its observed vapour-density is 6.74 the above formula requiring 6.97. Amylic diethoxalate is isomeric with ethylic ethyl-amylhy- droxalate described above. The nature of this isomerism is seen at a glance from the following constitutional formulae of the two bodies :-Ethylic ethyl-arnylhydroxalate { CAyHEto COEto Amylic diethoxalate . . The specific gravities in the liquid form and the boiIing points of arnylic diethoxalate and its isomer ethylic ethyl- amylhydroxalate are almost absdutely identical viz.Boiling point. Specific gravity. EthyliclethyI-amylhydroxalate 224'-225" C. 09399at 13' C. Amylic diethoxalnte . .. 225'C. *9323at 13' C. They are however at once distinguished by the products of their decomposition with alkalies ethylic ethyl-amylhydroxa- late giving ethylic alcohol and a salt of ethyl-amylhydroxalic acid whilst amylic diethoxalate yields amylic alcohol and a salt of diethoxalic acid. VIL Action of Zinc upon a Xwture of Arnylic Iodide and Amylic Oxalate When equivalent proportions of amylic iodide and amylic oxalate are gently heated in contact with zinc a brisk reac-tion soon sets in. After evolving much amylic hydride and amylene the whole solidifies to a gum-like mass which on distillation with water yields an oily liquid resembling that obtained when ethylic oxalate is employed.We have every reason to believe that the same series of ethers as those de-scribed under No. V. are here produced with the difference that they are amylic instead of ethylic ethers. This difference FRANKLAND AND DUPPA'S RESEARCHES of base however renders the separation of these ethers from each other a very difficult operation and we have therefore left this reaction comparatively unexplored. Two of these ethers were however collected ; the one boiling at about 280'-290' C. exhibited a composition approaching that of amy Zic diarnyloxalate CAy,Ho C17H3403' Or (COAyo . Amylic diamyloxalate is doubtless produced by the following consecutive reactions :-AmyG Amylic zincmonamyl- Zincic amylo- oxalate.diamyloxalate. amylate. + 20H2 = {giFF+ AyH + Zn"Ho2. Amylic zincmonamyl- Amylic di- Amylic diamyloxalate. amyloxalate. hydride. The second ether mentioned above boiled between 215' and 220' C. ; it was decomposed by alcoholic potash ; the potash- salt so obtained heated with dilute sulphuric acid yielded to ether an oily acid possessing the characteristic odour of caproic acid. This acid boiled with argentic carbonate suspended in water gave on filtration magnificent nacreous plates of a silver- salt which were very sparingly soluble in water only slightly acted upon by light in fact possessing all the properties of normal silver caproate and differing markedly from the isomeric silver diethacetate recently described by us.* Submitted to analysis this salt yielded results agreeing closely with thoae calculated from the formula of ailver caproate :-Unfortunately we did not submit to analysis the ether from which this caproic acid was obtained; but there can scarcely be a doubt that it was amylic caproate.We have stated that it boiled between 215" and 220O. The boiling point of amylic * PhilosophicalTransactions,vol. chi p. 37 and Jour. Chem. SOC. vol. iv (Ser. 2) p. 410. ON ACIDS OF THE LACTIC SERIES. caproate is not known; but ethylic caproate boils according to Fehling at 162’ C.; consequently the boiling-point of amylic caproate ought to be according t,o Kopp’s law 216*C. it number which lies between the points observed in the ether under consideration.It ib t>hus evident that the three variations in the action of’ zincamyljde upon an oxalic ether demibed above as giving rise to amylhydroxalic acid ethyl-amylhydroxalic acid and diamyloxalic acid do not exhaust the fertility of this reaction; and the production of caproic acid as above described shows that the action of these substances upon each other is sus-ceptible of yet a fourth modification in which the molecule of amylic oxalate appears to divide into its two constituent semi- molecules of amyloxatyl (COAyo) wliich then unite with amyl to form amylic caproate. {E:gz + Ay = 2CAyOAyo or 2 {gk%. Amylic oxalate. Amyl. Amylic caproate. The source of the amyl in this reaction is not difficult to discover ;for as above stated torrents of the usual products of its transformations (amylic hydride and amylene) were evolved during the operatiou; in fact it mas obvious that no inconsiderable portions of the zinc and amylic.iodide were occupied in the forniatioii of zincic iodide and amyl a con- Biderable proportion of the latter being ae uxsual transformed at the moment of separation into amylic hydride and amy- lene 2AyI + Zn” = Zn’? + Ay,. Meeting with this reaction as we have done only at the close of the above investigation we have not been able to ascertain whether or not it is one of general occurrence. It is true that we have not observed the formation of the fatty ethers in any of the foregoing reactions in which zinc and the iodides of the radicrils were employed; but the com-paratively low boiling-points of these ethers might easily have led to their being overloolred.We consider however this reaction of so much importance that we shall at once endeavour to ascertain whether or not it occurs in the other homologous cases giving rise to acetic ether in the case of VOL. XXII. F FRANKLAND AND DUPPA’S REBEARCBEB methylic iodide and to propionic ether where ethylic iodide is employed. We have already stated that the constitution of the acids of the lactic series has been the aubject of fruitful controversy amongst chemists. In this discussion widely different opinions have been advanced some have assigned to lactic acid the formula (C,H,,O,) and attributed to it a bibasic character; some have reduced this formula to C,H,O,.stilt retaining for the acid the game degree of basicity ; whilst others again have regarded it as monobasic and assigned to it the lower formula. This controversy respecking the constitution of an acid so intimately rglated to several of the most important families of organic compounds has been the incentive to numerous and highly important researches which have thrown vahmble light not merely upon the structure of the lactic series itself but also upon that of organic families allied to this series. Amongst the espeiimental investigations which have con- tributed to the elucidation of this subject we beg leave to refer to those of Wurtz,* Ulrich,f StreckerJ Briining,$ Perkin and Duppa.11 Again Wurtz Perkin Kekuld and especially K o1 be have by their acute theoretical.speculations most ably supplemented direct investigation. Unfortunately these researches and discussions were to a great extent limited to two members of this serieB viz. lactic and glycollic acid and this circumstance necemaril y furnished a comparatively small bask upon which to build purely theo- retical speculations. We are therefore not without hope that with the addition of the numerous members of this series described in the foregoing pages and with the light thrown upon them by their synthetical production we have reached a new stage in the inquiry whence a more extensive prospect may be obtained. Before proceedjng to take a survey of the new field thus opened up it is necessary fnst to call spacial attention to a negative or chlorous organic radical intimately connected with the compounds above described.* Cornptes Rendus vol. lii p. 1067. 5 Ann. Chem. Pharm. vol. xci p. 862. I-Ann. Chem. Pharm. vol. cix p. 271. 5 Ibid vol. civ p 191. II Ihid. vol. cviii p. 113. 59 ON ACIDS OF THE LACTIC SERIES. The Radical Oxatyl. An inspection of the above a?zd following formule for acids of the lactic series shows that through all the changes of the lactic acid type giving rise to the various species of acids men- tioned below the group COHO remains unaltered. We have also shown that the same group maintains its individuality unimpaired throughout the acetic and acrylic series of acids ; in fact it is the presence of this group which impresses upon an organic compound the acid character.We believe therefore that its claims to be considered a compound radical are at least equal to those of any other group of elements to which that term has been applied. We propose for this radical the name oxatyP-a word recall- ing at the same time its acidifying power aid its coii-nexion with oxalic acid which ip the isolatcd molecule of this radical {EE* Oxalic acid. We have in fact experimentally proved above that when ethylic oxalate is acted upon by nascent arnyl it is converted into ethylic caproate + {COEto {CBuH -COEto CBuH -{~~k~~ Ethylic oxalate. Amyl. Ethylic caproate. Oxatyl is closely related to cyanogen the two radicals pass-ing into each other in a host of reactions ; heme the production of cyanides from the ammonium salts of the fatty acids on the one hand and the syathesis of acids &om certain cyanogen compounds on the other-a reaction which was first pointed out by Kolbe and Frankland,? and has of late yielded such magnificent results in the hands of Maxwell Simpson and of Kolbe and Hugo Muller.5 Oxatyl would.obviously be the most appropriate name for this radical. ha& it not already been applied to the two compounds CO and C,O,. vhilst tbis paper is passing through the press we find that the radical oxatyl has already been fully recognized by Bu t 1e r o w. t Memoirs of Chem. So .vol. iii (1847) p. 386. ++ Philosophical Transactions 1861 p.61; and Journ. Chem. SOC. vol. xviii p. 331. 3 Jonm. Chem. Soc. vol. xvii p. 109 F2 FRANKLAND ANL DUFPA’S RESEARCHES {;g;* Cyanogen. The researches of these chemists prove that the introduction of cyanogen into an organic compound and its subsequent transformation into oxatyl converts that compound into an acid or if already an acid increases its basicity by unity for each semi-molecule of oxatyl so developed this result being apparently quite independent of the position of the oxatyl in the molecule. The semi-molecule of oxatyl as 1he above molecular formula Bhows may be regarded as methyl (CH,) in which two atoms of hydrogen have been replaced by one of oxygen and the third br hydroxyl (Ho). The individualizing of this group confers upon the formula of most of the great families of organic com- pounds a simplicity hitherto unattainable without ignoiing their atomic constitution.The passage from one organic family to another thus becomes a mere substitution of the hydroxyl con- tained in oxatyl by other radicals either simple or compound. When for instance it is replaced by the peroxide of a metal the acid of which the oxatyl is a constituent becomes converted into a salt thus Sodic acetate.. .. Barb acetate .. *f CONao Sodic rJuccinate .. ‘2’4~0Nao* co Baric succinate .. ..C,H,COBao”. With the hydroxyl replaced by methoxyl ethoxyl &c. an ethereal salt is produced as Ethylic acetate . a COEto Ethylic succinate .. ’‘‘2%COEto‘ CHHo (COEt 0) Ethylic citrate CH(C0Eto) .a. CH2(COEto) ON ACIDS OF Tm LACTIC SERIES. When the hydroxyl is replaced by hydrogen an aldehyde or an aldehydoid acid is the result. Thus Aldehyde .. .. COH Glyoxylic acid . '* {COHO* Again if a basylous monad radical take the place of the hydroxyl a ketone is formed Further if chlorine bromine &c. replace the hydroxyl a haloid compound of the so-called 64 acid radical " is the result Acetylic chloride .. ** {E%r cocl Succinylic chloride . ''C2H4COCy Again if the hydroxyl be replaced by oxygen an anhydride is formed Acetic anhydride Succinic anhydiide . . C2H:g0. And finally if replaced by amidogen an amide or amido-acid results t Succinamide .... It may be objected that the groap of elements which is thus invested with radical functions lacks one of the fbndamentat characteristics of a radical by its proneness to change ; but the -characteristic of perRistency is exhibited by the commody FRANKLAND AND DUPPA'S RESEARCHES received radicals in a very varied degree; and even methyl itself which certainly possesses it in the most marked manner readily permits of its hydrogen being replaced by chloriue or bromine on the one hand and by sodium on the other. All compound radicals are purely conventional groupings of elements intended to simplify the expression of chemical clmnge ; and inthis respect we believe hhe' group oxatyl enter- ing a8 it does into the constitution of nearly every organic acid has as valid a claim to a distinct name as the most univer- sally recognized radicals.Its admission relidem possible the following very simple expression of the law gweriiing the basicity of nearly all organic acids :-An organic acid containing n semi-molecules of oxatyl is n-basic. Classijcation of the Acids of the Lactic Series. We propose classifying all acids of thelactic seriea at present lciiown or which could be obtained by obvious processes into the following eight divisions :-1. Normal Acids. 2. Etheric Normal Acids 3. Secondary Acids. 4.Etheric secondary Acida 5' Normal Olefine Acids. 6. Etheric Normal Olefine Acids. 7. Secondary Olefine Acids. 8. Etheric Secondary Olefine Acide.1st. AforinaZ Acids.-A normal acid of the lactic seriea may be aefined as one in which an atom of carbon is united with oxatyl hydroxyl and at least one atom of hydrogen. The general formula of theae acids is therefore + In this formula R may be either hydrogen or any monad alcohol raclicd; and the number of acids possea&g the same atomic weight znd belonging to this division is determined by the + umber of isomeric modifications of which the radical R irs susceptible. Thus of the acids containing two three or four ON ACIDS OF THE LACTIC SERIES. atoms of carbon there can be only one of each belonging to this division because these acids cannot contain an alcohol ra&cal higher in ihe eeries than ethyl which is not susceptible of isomeric modification ; but a normal acid containing propyl can have one isomer in this division the two acids containing respectively propyl (CEtH,) and isopropyl (,CMe,H).For acids of t'his division containing normal alcohol radicals only the following general graphic formala may be given :-In the case of glycallic acid n = 0. The following are the acids at present known belonging to this division":-Gclgcollic acid. *. Lactic acid . . 0. CEtHHo Oxybutyric acid (COHO " CBuHHo Leucic acid . . .. .* {COHO 2nd. Etheric Normal Acids.-An etheric normal acid of the lactic series is constituted like a normal acid but contains a monad organic radical chlarous or basyloue in the place of the hydrogen of the non-oxatylic hydrosyl.The following is there-fore the general formula of these acids in the graphic formula n as before may = 0 * Since the above was written Fittig has produced valerolactic acid the rational formula of which ia doubtlese 1~~~Ho.-April 29th 1866. FRANKLAND AND DUPPA’S RESEAROHES The number of possible isomers belonging t.0 this division is very great; for in addition to those of which the normal acids + containing R of the same value are susceptible a host of others + + must result from the complementary variation of R and R. The lowest member of the division metliylglyuollic acid (isomeric with lactic acid) is the only one incapable of isomeric modifi- cation. The following examples mill serve to illustrate the constitu- tion of the acids belonging to this division :-Methylglycolh acid .... {;;go. Ethyl-lactic acid ,. .. Aceto-lactic acid .. .. . {~~;~Aco* . 3rd. Secondary Acids.-A secondary acid of the lactic series is one in which an atom of carbon iti united with oxatyl hydroxyl and two semi-mobcubes of an alcohol radical. The general formula of these acids is I 0.. .......@.............. ............@ or ..... . . .. . 1 I @=@ Ina I 8 In the graphic expression the values of n and m may differ but both are positive integers and neither may = 0. In the + symbolic formula R must be a monad alcohol radical. All the known members of this division me described in the foregoing pages. The following examplea will serve to illnstrate their constitution :-Dimethoxalir acid,... {ggO. * ACO= peroxide of acetyl C2H302. ON ACIDS OF THE LACTIC SERIES. ti5 Ethomethoxalic acid . . { ~~~~Ho. Diethoxalic acid . . The number of acids possessing the same molecular weight and belonging to this division is determined first by the comple- mentary variation of the two alcohol radicals and secondly by the number of possible isomers of these radicals. The two lowest terms of the series are alone incapable of isomeric modi- fication by either of the causes mentioned. 4th. Etheric Secondary Acids.-These acids stand in the same relation to the secondary as the etheric normal to the noimal acids ; they consequently contain a monad organic radical in the place of the hydrogen of the non-oxatylic hydroxyl.The following is therefore the general formula of these acids :-We have obtained acids belonging to this division which we hope to describe in an early communication. 5th. Normal Olejne Acids.-A normal olefine acid belonging to the lactic series is one in which the atom of carbon united with ovatyl is not combined with hydroxyl and in which the atom of carbon united with hydroxyl is combined with not less than one atom of hydrogen. The following are the general graphic and symbolic formule of the acids belonging to this division:-In both these formula n mmt be a podtive integer and can- F'RANELAND AND DUPPA'S RESEARCHES + nut = 0 but R may be either hydrogen or a monad alcohol radical.The olefines of these acids may belong to either the ethylene or ethylidene series. The following are the only acids at present known belonging to thie division :- Paralactic acid .. lcofio Paraleucic acid .. {ig. We give the name paraleucic acid to the acid obtained by Lippmann* in acting with phosgene gas upon amrlene. Thk body has not yet been completely investigated ; Lippmann regards it as identical with leilcic acid but as it is produced by a reaction exactly homologous with that by which paralactic acid is formed we believe it will be found to differ slightly fiom leu& acid ag paralactic does from lactic acid. The number of isomers in thia division will obviously depend first + upon the complementary variations of R and (CH2)n; secondly + upon the isomeric niodifications of which R is susceptible; and thirdly upon the isomeric modifications of (CH,),.6th. Etheric Normal OleJne Acids.-These acids differ from the normal olefine acids only in having the hydrogen of the non-oxatylic hydroxyl replaced by an organic radical positive or negative ; therefore their general formula is Aa in the fifth division n must be a positive integer and cannot + = 0 whilst R may be either hydrogen or a monad alcohol + radical; but R must be a monad compound radical either acid or alcoholic. * ban. Ch. Phm. cxxix..81. ON ACIDS OF THE LACTIC SERIES 7th. Seconda?y Olt$ne Acids.-A secondary olefme acid of thk series is one in which the atom of carbon united with oxatyl is not combined with hydroxyl and in which the atom of carbon united with hydroxyl is also combined with two monad alcohol radicals as shown in the following formulae :-In both of these formulae n must be a positive integer and t cannot = 0 and R muat be a monad alcohol radical.8th. Etheric Secondary Olejne Acids.-These acids are related to the secondary olefine acids in the same way as the sixth division to the fifth. No member of the seventh or eighth divi-sion has yet been formed. Isomerzsrn in the! Lactic Series. The members of the lactic series may be defined as acids con- taining one aeini-molecule of oxatyl the fourth bond of the carbon of which is united with the carbon of a basylous group containing one semi-molecule and one only of hydroxyl or of the peroxide of a radical either alcoholic or acid.The following examples ex- pressed in the grapbic notation of Crum Brown,' will serve to illustrate this definition. * Edinburgh Phil. Trans.for 1864 p. 707. It is much to be desired that chemista should employ these graphic formnlse in all caaes where they wish to express the mode in which they suppose the elements of a chemical compound to be combined. It is often extremely difficult to trace in aymbolic formulae the exact meaning which an author attaches to the grouping of letters ;in graphic formnlse no sudl difficulty can arise ; and we therefore think that the u~e of these formulse where constitutional expressions are intended will greatly tend to clearness and precision.It is scarcely necessary to repeat Crum Brown's remark that such formulse are not meant to indicate the physical but merely the chemical position of the atoms. For the pur- pose of rendering the graphic more easy of cornpalison with symbolic formuh we hve sometimes dissected the former into their constituent radieals by dotted lines 8s above. Thisdissection whilst assisting the eye in reading the f&nulm cannot fail to sugest the for the most part purely conventional character of such radicals. FRANKLAND AND DUPPA'S RESEARUHES Acids of the Lactic Series. 0 I io ................. -g-@ i ....I ............ ....1 ............ q" I ;....J ............ 69 Lactic acid. Methyl-lactic acid, @ Aceto-lactic xacid.The synthetical study of the acids of this series affords an insight into numerous and interesting cases of isomerism which have hitherto received at best but. a very imperfect explanation. Commencing with the lowest member of the series we have for glycollic acid the formula- @ 1 ...,........I ............ An inspection of thia foimula shows that gIycollic acid admits of no iaomeric modification except with a total change of type unless a difwent value be assigned to the individual bonds of an atom Of carbon. The part of the formula below the dotted line represents oxatyl which a8 we have already shown cannot be altered without sacrificing the acid character of the compound there remains therefore only the part of the foimula above the dotted he which admits of the following modification :- ON ACIDS OF THE LACTIC SERIES.The acid represented by the formula so modified no longer comes within our definition of the lactic series. It is carbo- meth-ylic acid and differs essentially from glycollic acid and the lactic series in general inasmuch as the carbon of its chlorous radical oxatyl is linked to the carbon of the basylous radical by oxygen.* There being no decisive evidence that homolactic acid differs from glycollic acid experiment and theory both agree in asserting that the formula C,H40 represents only one acid in the lactic seriea. Proceeding now one step higher in this series we have in the formula of lactic acid an expression capable of the following three variations without quitting the lactic type :-* Bearing this constitution of carbomethylic acid in mind we have only to go one step further in order to perceive the constitution of carbonic acid itself and the anomalous basicity of that acid ;for if in the above grapbic formula for carbome-thylic acid we replace the methyl by hydrogen we have 0 @-&El I 69 I @=@ h 1 0 Carbomethylic acid.Carbonic acid. It is thus evident that our radical oxatyl when united with hydroxyl haa sJlfEcient chlorous power to produce a feebly bihasic acid but inasmuch as carbonic acid is not included in the category of organic acids it forms no exception to the law above enunciated. FRANKLAXI3 AND DIPPA’S RESEARCHES No.1. No.2. No.3. 69 I ? @-@-@ I Or expressed aymbolically No. 1. INo. 2. No. 3. All the acids represented by the above formulae are known. The first expresses the constitution of lactic acid which be- longs to the normal diviaion ({gig:’) of the series described at page 62; the second shows the atomic arrangement of paralactic acid whilst the third representa methyl-glycollic acid. The proof that the first two of these acids are so con-stituted is afforded by the beautiful synthetic processes for their production devised by Wislicenus* and Lippmann.7 The first of these chemists has shown namely that ethylidene cyanhydrate is converted by ebullition wikh potash into a salt of lactic acid whilst ethylene cyanhydrate is transformed under similar circumstances into paralactic acid.Lip p m a n n has also rJhown that by the action of phosgene gas upon ethylene paralactic acid is produced. Now the formation of ethylidene or rather of its compounds scarcely leaves a doubt that this body if isolated would have the following atomic constitu- tion :-* Ann. der Ch. nnd Pharm. Bd. cxxviii. 5. 1. + Ibid. Bd. cxxix. S. 81. Crum Brown has already pointed out this relation between lactic and paralactic acids as well as the formula of ethylene given below.-Edinburgh Phil. Trans. for 1864 p. 712. ON AUIDS OF THE LACTIC SERIES it would consist of a gemi-molecule of methyl united with an atom of carbon two of whoge bonds satisfy each other Thus the for- mation of ethylidenic dichloride from aldehyde and phaspho~ chloride takes place as follows :-Aldehyde.Ethylidenic dichloride. the oxygen in the aldehyde being simply replaced by chlorine. There now only remains one possible formula for ethylene vie. :-Such then being the comtitution of ethylidene and ethylene it follows that the former ought to give riBe to an acid of the constitution shown in formula No. 1 whilst ethylene should produce an acid agreeing with formula No. 2. The acih actually produced from these sources are lacti;? and paralactic acids; hence we believe No. 1to be the constitutionalfoimula of lactic acid and No. 2 that of paralactic acid a conclusion which har- monizes perfectly with all the reactions in which the production of these acids can be traced.ThuB in the formation of lactic acid by the oxidation of propylic glycol,* we have CMeHHo CMeHHo+ oqm {COHO LL L Propylic glycol. Lactic =id. Again the production of this acid fiom ethylidenic cyanhy- drate * Wurtz Ann.der Chem. und Pharm. Bd. cv. 8. 206. fCH.Ho '24-= FRANKLAND AND DUPPA'S RESEARCHES CH {gEboCy -k OKH OH = {CHho(C0Ko) + NH,. Ethyli denic Potassic lactate. cyanhydrate. The formula given for potassic lactate in this equation is only apparently different in type from that previously used for lactic ac.id since In Ulrich's" interesting reaction by which chloropropionic acid is transformed into lactic acid we have the following change :-Chloropropionic Potassic lactate. acid. The production of lactamic acid (alanin) and that of lactic acid from the latter by the action of nitrous acid are also dearly confirmatory of the above view.{ g$NH,) + Cg"'+ OH + HC1 = {Et&:(NH2) + NH,Cl Ammonic Hgdrocyanic Lactamic add (alanin). aldehyde. -acid. Lacgmic acid (alanin). Nitrous acid. Lactic acid. Not the least interesting reaction illustrative of the constitu- tion of lactic acid is the formation of this acid by the action of nascent hydrogen upon pyruvic acid recently described by W is1ic enu s.7 CMeO CMeHHo (COHO + = {COHO Pyruvic acid. Lactic acid. By an analogous reaction glyoxylic acid which we regard as the next lower hornologue of pyruvic acid has been transformed by D e bust into glycollic acid. * Ann. Chem.Pharm. cix. 271 t. Ibid. cxxvi. 226. $ Ibid. cxxvii. 145. ON ACIDS OF THE LACTIC SERIES. CHO {::em {COHO -k H2 = Qlyoxylic acid. Glycollic acid. In a similar manner it can be demonstrated that the above formula No. 2 expresses the constitut<ion of paralactic acid which belongs to the fifth or olefine division of these acids C~~HH~ C~HH~ { (cH,),(cIH~) 01’ { (((% . That paralactic acid possesses this constitution is proved first by its production from cyan-hydric glycol CH,Ho {:2$&) + KHo + OH = CH2 + NH ; LOKo Cyan hydric L Potassic glycol. paralactate. and secondly by its formation from phosgene gas and ethylene {g2+ coc1 = CH,(COCl) ; Ethylen;. PhorJgene. Chloride of B chlorpropionyl.CH,(COCl) -t 30KH = {~~~oKo) + 2KC1 + OH,. Chloride of Potaaeic B chlorpr opionyl . paralactate. By the action of waterupon the chloride of p chIorpropiony1 a body of the composition of chloropropionic acid results; but inasmuch as this body yields paralactic acid by ebullition with potash whilst chloropropionic acid gives under the same cir-cunzstances lactic acid it follows that the former chloro-acid must be isomeric and not identical with the latter. Now although the formula of propionic acid does not admit of any isomer yet that of chloropropionic acid does as is Heen in the following graphic formula :-VOL. XXII. FRANKLAND AND DUPPA’S RESEARCHES No. 1 Ro. 2. I @-@-@ I A comparison of these fomdai! with those of lactic and para-lactic acids (page 70) shows at a glance that No.1 is the chloropropionic acid which yields lactic acid whilst No 2 isiso-chloropropionic acid which by the substitution of its chlorine by hydroxyl must yield paralactic acid By the action of nascent hydrogen both isomeric chlorides will obviously produce the same propionic acid. The cause of the isomerism of methyl-glycollic acid (No. 3 page 70) is so obvious as to require no further explanation. Proceeding to the next higher stage in the series mch is the rapid increase of isomerism that we now encounter no less than eight possible iBorners all within the lactic family. Etheric normal. Normal. Secondary. c No. 1. No. 2. No. 3 rn CMe Ho CH Eto {EEHO* (cod0 {co~o {,EEMe0* Normal olefine.-Etheric normal olefine. No.5. No.6. No. 7. No.8. CH,Ho CH2Ho CMeHHo CH,Meo {% ’ {EE {ao coho {%lo ’ ’ Of these acids Noa. 1 2 and 3 are known. No. 1is oxybu-tyric acid; No. 2 is dimethoxalic acid which is probably identical wit11 Stadeler’s acetonic acid.* On this assumption the for- mation of the latter by the action of hydrocyanic and hydro- chloric acids upon acetone is easily intelligible. * Ann. Ch. Pharm. cxi 320. These acids have since been proved to be identical. ON ACIDS OF THE LACTIC SERIES. {:the + CN"'H + 204 + HCl = (COHO CMe2Ho + NVH4Cl. Acetone. Acetonic or dimethoxalic acid. The properties of acetonic acid and its salts aB described by Stadeler agree well with those which we have observed in dimethoxalic acid and its compounds both acids evolve an odour of acetone on being heated with potassic hydrate and are decomposed without blackening by concentrated sulphuric acid with evolution of much gas.The third of the above formulae is obviously that of Heintz's ethyl-glycollic acid.* The origin of Wu rt z' s butylactic acid which was prepared by an analytical process does not permit of any safe conclusion being drawn as to its constitution. Of the possible acids containing five atoms of carbon only one (the ethomethoxalic acid described a.bove) is kn0wn.t Of acids containing six atoms of carbon three are known to which we assign the following formulae?- CBuHHo Leucic acid . . .. {COHO Diethoxalic acid . .Paraleucic acid . . me {% The above formula for leucic acid is founded upon Lim-prich t'st interesting reaction for the spithetical production of this acid from valeric aldehyde and hydrocyanic acid. Kolbe has shown that valeric acid contains butyl; conse- quently valeraldehyde has the constitution expressed by the C Bu formula and Limpricht's reaction may therefore be explained by the following equation * Pogg. Ann.cix. 331. ( { ErgH0), f-Valerolactic acid just diacovered by Fittig forms a second Its isomerism with ethomethoxalic acid is proved by its melting-point which ia 80°C. whilst ethomethoxalic acid fusea at 63"C.-April 29 1866. $ Ann. Ch. Pharm. xciv 243. FRANKLAND AND DUPPA'S RESEAROHES Ammonic Leucin. valeraldehyde.Such being the rational formula of leucin it8 transformation into leucic acid by nitrous acid determines the constitution of leiicic acid {Egy'NH') + N"'OH0 ={COHO CBuHHo + OH + N,. Leucin. Nitrous acid. Leucic acid. We entertain no doubt of the isomerism of leucic and dieth- oxalic acids although we have not yet been able to observe any substantial difference between them ;both acids melt at nearly the same temperature (leucic acid at 73"C. and dieth- oxalic acid at 74O.5 C.). Waage* states that zincic leucnte requires 300 parts of water at 16" for its solution whilst we find that zincic diethoxalate requires 302 parts at 16" C-Doubtless the study of the products of the tr6nsformation of these acids will reveal the difference existing between them we are at present preparing leucic acid for this purpose.We have also mentioned in the experimental part of this paper that diethoxalic acid prepared from methylic diethoxalate yields a silver-salt which differs from that obtained with the acid horn ethylic diethoxalate ; and we have even noticed indications of a third synthesised isomer ; but we reserve the further inquiry into the nature of these acids for a future communication. On the Proximate Analysis of the Acids of the Lactic Series. The investigations recorded in the foregoing pages show that the division of acids of the lactic series which we have termed gecondary acids is derived from oxalic acid by the substitution of two aemi-molecules of monad alcohol radicals for one atom of oxygen in that acid.This substitution destroys one of the semi- molecules of oxatyl in oxalic acid thus reducing the latter from a dibasic to a rnonobasic acid. This theory of the structure of the secondary acids so unmistakeably indicated by the mode of their formation we have also extended to the normal acids f Ann Ch.Pharm. cxviii 295. 0s ACIDS OF THE LACTIC SERIES. 77' Which are thus regarded as derived &om oxalic acid bythe replacement of one atom of' oxygen in the latter either by hydrogen alone it^ in glycollic acid or by one atom of hydrogen and one semi-molecule of a monad alcohol radical :-{EE {EkP {::g:Ho Oxalic acid. Qlycollic acid. Lactic acid. Hitherto we have advanced only synthetical evidence of this constitution ; but the question presents itself if the radicals indicated by our hypothesis really exist in these acids can they not be again disentangled from the complex molecule either in the coiidition in which they entered it or at all events in the form of well recog~zed derivatives ? Such analytical evidence although possessing far less weight than synthetical may still be of service as corroborative testimony.We will therefore show how such a proximate analysis of these acids can be accomplished and for this purpose we will first endeavour to demonstrate that if in a chain of carbon atoms any two be united by two bonds of each the remaining atoms being united to each other by one bond only the chain is more liable to rup-ture at the point of double junction than at any other.We have shown how in dimethoxalic acid a weak link of this kind can be developed;* for if' dimethoxalic ether be treated with phosphorous chloride it is transformed into ethylic methacry- late the acid of which contains two atoms of carbon in the condition just indicated. The nature of this transformation and the link in the chain which is thus weakened are ahown in the following graphic formulae :-W U Dimethoxalic acid. Methacrylic acid. # Journ. Chem. SOC.vol. xviii. p. 141. FRANKLAND AND DUPPA'S RESEARCHES If methacrylic acid be now heated with potash the acid molecule breaks up at the place indicated by the dotted line with the production of propionic and formic acids :-L Met,hacrylic Potassic Potassic acid.propionate. forplate. Q @ Propionic acid. Formic acid. Thus one of the atoms of methyl originally introduced into oxalic acid is now extracted in the shape of its well-known derivative formic acid. We have proved by synthesis that propionic acid is methacetic acid { gEiy2 ; but it still remains to extract this second atom ofmethyl fiom it. For thirs purpose we might transform the propionic acid into chloropropionic acid and the latter into ethylic lactate by well-known processes when by repeating the reactions with phosphorous chloride and caustic potash above described the second atom of methyl like the first ought to be eliminated as formic acid; but unfor-tunately the reaction with terchloride of phosphorus although so easy with a secondary acid fails when applied to a normal acid of the lactic series and we are therefore diiven to seek other means of obtaining the end in view.It is however only necessary to avail ourselves of the beautiful reactions of K 01b e* in order to extract the remaining atom of methyl in its integral farm. Thus if the lactic acid derived a8 above described be submitted to the action of electrolytic oxygen it is transformed into carbonic acid and aldehyde {gtg:Ho + 0 = CMeHO + COHO,. L htic acid Aldehyde. Carbonic acid. * Apn Chmn Pbm. cxiii 244. ON ACIDS OF TEE LACTIC SERIES. It will be oberved that one of the atoms of oxahyl in the original oxalic acid ({g",::) is here eliminated as the well- known derivative carbonic acid.The aldehyde thus obtained which contains the methyl sought for must now be oxidized to acetic acid; and it then only remains to resort once more to electrolytic oxygen to liberate the methyl together with the remaining atom of oxatyl originally present in the oxalic acid 2{gzfio + 0 = {:2+ 2C0 + OH,. Acetic acid. Methyl. We tabulate below the materials used in the synthesis of dimethoxalic acid side by side with the products obtained bY the analysis of that acid :-Materiala for Synthesie. Results of Analysis. ' I. 11. -\ I. 11. \ 2COH0,. Carbonic acid. CH,. Methyl. COHHo. Formic wid. Oxalic acid. Methyl. In like manner the radicals contained in the other acids belonging to the normal and secondary divisions of the lactic series can be extracted whilst it has already been proved by Butlerow" that etheiic normal acids when treated with con- centrated solution of hydriodic acid yield up as iodide the alcohol radical which in these acids is linked to carbon by oxygen; thus in the case of ethyl-lactic acid Ethyl-lactic Lactic acid.Ethylic acid. iodide. The olefine acids are as yet too little known to allow of their constitution being thus analytically investigated. These acids do not derive from oxalic acid by substitution alone but by simultaneous- addition of an olefine. They may in fact be regarded as standing somewhat in the same relation to the * Ann. Chem. Pharm. cxviii 326. FRANKLAND AND DUPPA'S RESEARCHES ETC. normal acids as the polyethylenic glycols occupy with regard to the normal glycols as seen from the following comparison :-{E:::* Glycol.{&* (EiP* {:yo. CH,Ho Glycollic acid. COHO CH,Ho P&dactic acid. Diethylenic glycol. We beg to append the following summary of conclusions to which our investigations have conducted us :-1. All acids of the lacti series are essentially monobasic. 2. These acids are of four species viz.,normal secondary normal olefine and secondary olefine acids; and each of these Bpecies has its own etheric series of acids in which the hydrogen of the hydroxyl contained in the positive or basylous constituent of the acid is replaced by a compound organic radical either positive or negative. 3.The normal acids are derived from oxalic acid by the re- placement of one atom of oxygen either by two atoms of hydrogen or by one atom of hydrogen and one semi-molecule of an alcohol radical. 4. The secondary acids are derived from oxalic acid by the replacement of one atom of oxygen by two semi-molecules of monad alcohol radicals. 5. The olefine acids are derived from oxalic acid by a like substitution of two monad positive radicals for one atom of oxygen with the insert'ion of an olefine or dyad radical (CnH2J between the two semi-molecules of oxatyl. 6. The acids of the lactic series stand to the acids of the acetic series in the"very simple relation fist pointed out by Kolbe viz. that by the replacement by hydrogen of the hydroxyl ethoxyl &c.contained in the positive radical of an acid of the lactic series that acid becomes converted into a member of the acetic series. 7. The acids of the lactic series stand in an almost equally simple relation to those of the acrylic series as is seen on corn-paring the following formulae :-Lactic acid. Acrylic acid.