13. The orderly arrangement of the several layers and their elementary parts is maintained by a frame of connective tissue which consists of1, an unbroken homogeneous membrane bounding the inner surface of the retina, the membrana limitans interna; 2, a fenestrated membrane which holds the rods and cone-bodies, the membrana limitans externa, first correctly described by Schultze; 3, an intermediate system of tie-fibresMüller's radial fibres-connected with which in the layer of inner granules are certain oblong and fusiform bodies of uncertain nature; 4, the intergranular layer; 5, an areolated tissue, open in the layers of outer and inner granules, and very closely woven in the granular layer. 14. No blood-vessels occur in the reptilian retina. II. "Notes of Researches on the Acids of the Lactic Series.-No. I. Action of Zine upon a mixture of the Iodide and Oxalate of Methyl." By E. FRANKLAND, F.R.S., Professor of Chemistry, Royal Institution, and B. F. DUPPA, Esq. Received February 10, 1864. In a former communication by one of us*, a process was described by which leucic acid was obtained synthetically by the substitution of one atom of oxygen in oxalic acid by two atoms of ethyl. The relations of these acids to each other will be seen from the following formulæ + : 2 C, H, C, O он OH Leucic acid. Oxalic acid. This substitution of ethyl for oxygen was effected by acting upon oxalic ether with zincethyl. On distilling the product with water, leucic ether came over, which on treatment with an alkali yielded a salt of leucic acid. We have since found that this process may be much simplified by generating the zincethyl during the reaction, which is effected by heating a mixture of amalgamated zinc, iodide of ethyl, and oxalic ether in equivalent proportions to the necessary temperature. The operation may be considered complete when the mixture has solidified to a resinous-looking mass. This, treated with water as in the former reaction and distilled, produces quantities of leucic ether considerably greater than can be obtained from the same materials by the first mode of operating. Thus the necessity for the production of zincethyl is entirely obviated, the whole operation proceeds at the ordinary atmospheric pressure, and a larger product is obtained. We find that this process is also applicable to the homologous reactions with the oxalates and iodides of methyl and amyl. By it we have obtained * Proceedings of the Royal Society, vol. xii. p. 396. + The atomic weights used in this paper are the following:-C=12, 0=16 and Zn=65. numerous other acids belonging to the lactic series, which we have already more or less perfectly studied, and the history of which we propose to lay before the Royal Society as our researches proceed, reserving for a later communication our views regarding the constitution of this series of acids, and the theoretical conclusions arrived at in the course of the inquiry. In the present communication we will describe the application of this reaction to a mixture of iodide of methyl and oxalate of methyl. Two equivalents of iodide of methyl were mixed with one of oxalate of methyl, and placed in contact with an excess of amalgamated and granulated zinc in a flask, to which an inverted Liebig's condenser, provided with a mercurial safety tube, was attached. The flask was immersed during about twenty-four hours in water maintained at a temperature gradually rising from 70° C. to 100° C. as the reaction progressed towards completion. At the end of that time the mixture had solidified to a yellowish gummy mass, which, on distillation with water, yielded methylic alcohol possessing an etherial odour, but from which we could extract no ether. The residual magma in the flask, consisting of iodide of zinc, oxalate of zinc, and the zinc-salt of a new acid, was separated from the metallic zinc by washing with water. It was then treated with an excess of hydrate of baryta and boiled for a considerable time; carbonic acid was afterwards passed through the liquid until, on again boiling, the excess of baryta was completely removed. To the filtered solution recently precipitated oxide of silver was added until all iodine was removed. The solution separated from the iodide of silver was again submitted to a current of carbonie acid, boiled, and filtered. The resulting liquid, on being evaporated in the waterbath, yielded a salt crystallizing in brilliant needles 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 The acid of this salt, for which we provisionally propose the name dimethoxalic acid, is obtained by adding dilute sulphuric acid to the concentrated solution of the baryta-salt and agitating with ether. On allowing the ether to evaporate spontaneously, prismatic crystals of considerable size make their appearance. These yielded, on combustion with oxide of copper, results nearly identical with those required by the formula CH, Dimethoxalic acid is a white solid, readily crystallizing in beautiful prisms resembling oxalic acid. It fuses at 75°-7 C., volatilizes slowly even at common temperatures, and readily sublimes at 50° C., being deposited upon a cool surface in magnificent prisms. It boils at about 212° C., and distils unchanged. Dimethoxalic acid reacts strongly acid, and unites with bases, forming a numerous class of salts, several of which are crystalline. In addition to the baryta-salt above mentioned, we have examined the silversalt, which is best formed by adding oxide of silver to the free acid, heating to boiling, and filtering, when the salt is deposited in star-like masses of nacreous scales as the solution cools. On analysis, this salt gave numbers closely corresponding with those calculated from the formula Attempts to produce an ether by digesting the free acid with absolute alcohol at a temperature gradually raised to 160° C. proved abortive, traces only of the ether being apparently formed. Thus the final result of the action of zinc upon a mixture of iodide and oxalate of methyl is perfectly homologous with that obtained by the action of zincethyl upon oxalic ether. In the methylic reaction, however, no compound corresponding to leucic ether was obtained. This cannot create surprise when it is remembered that dimethoxalic ether approaches closely in composition to lactic ether, which is well known to be instantly decomposed by water. We have sought in vain to obviate this decomposition of dimethoxalic ether by adding absolute alcohol in place of water to the product of the reaction. February 25, 1864. Major-General SABINE, President, in the Chair. I. "On the Joint Systems of Ireland and Cornwall, and their Mechanical Origin." By the Rev. SAMUEL HAUGHTON, M.D., F.R.S., Fellow of Trinity College, Dublin. Received February 8, 1864. (Abstract.) This paper is a continuation of a former paper "On the Joints of the Old Red Sandstone of the Co. Waterford," published in the Philosophical Transactions' for 1858, and contains the results of the author's observations for some years, in Donegal, the Mourne and Newry Mountains, Cornwall, and Fermanagh, with deductions from theory. The author establishes the existence in Waterford of a Primary Conjugate System of Joints, and of two Secondary Conjugate Systems, lying at each side of the Primary at angles of 27° 5' and 37° 11'. In Donegal there exists a Primary Conjugate System, and a Secondary System, making with the Primary an angle of 32° 24'. In the Mourne and Newry Mountains there is a Primary Conjugate System, and two Secondary Systems at each side of the Primary, making angles of 31° 46′ and 30° 56'. In Cornwall there is a Primary and also a Secondary Conjugate System, making an angle of 27° 28'. And in Fermanagh there are Primary and Secondary Systems, forming an angle of 31°1'. Having given, in detail, the observations on which the preceding results are founded, the author says:-" Collecting together into one Table the results of the preceding observations, we find the following Table of Primary and Secondary Joints (True Bearings) : If we compare The only remarkable agreement as to direction of joints disclosed by the preceding Table is that between Waterford and Cornwall. together the Primary and Secondary Joints in each locality, we find the following Table of Angles between Primary and Secondary Joints : : This Table discloses a very interesting and unexpected result; viz. that in Waterford, Donegal, Mourne, and Fermanagh, the angle between the Primary and first Secondary Joint-Systems ranges between the narrow limits of 27° 5' and 32° 24', and that in Waterford, Mourne, and Cornwall, the angle between the Primary and second Secondary Joint-Systems ranges from 27° 28' to 37° 11'. 144 Supposed Identity of Biliverdin with Chlorophyll, &c. [Feb. 25, The paper concludes with a brief deduction of the observed laws of Conjugate and Secondary Joints from known mechanical principles. II. "On the supposed Identity of Biliverdin with Chlorophyll, with remarks on the Constitution of Chlorophyll." By G. G. STOKES, M.A., Sec.R.S. Received February 25, 1864. I have lately been enabled to examine a specimen, prepared by Professor Harley, of the green substance obtained from the bile, which has been named biliverdin, and which was supposed by Berzelius to be identical with chlorophyll. The latter substance yields with alcohol, ether, chloroform, &c., solutions which are characterized by a peculiar and highly distinctive system of bands of absorption, and by a strong fluorescence of a blood-red colour. In solutions of biliverdin these characters are wholly wanting. There is, indeed, a vague minimum of transparency in the red; but it is totally unlike the intensely sharp absorption-band of chlorophyll, nor are the other bands of chlorophyll seen in biliverdin. In fact, no one who is in the habit of using a prism could suppose for a moment that the two were identical; for an observation which can be made in a few seconds, which requires no apparatus beyond a small prism, to be used with the naked eye, and which as a matter of course would be made by any chemist working at the subject, had the use of the prism made its way into the chemical world, is sufficient to show that chlorophyll and biliverdin are quite distinct. I may take this opportunity of mentioning that I have been for a good while engaged at intervals with an optico-chemical examination of chlorophyll. I find the chlorophyll of land-plants to be a mixture of four substances, two green and two yellow, all possessing highly distinctive optical properties. The green substances yield solutions exhibiting a strong red fluorescence; the yellow substances do not. The four substances are soluble in the same solvents, and three of them are extremely easily decomposed by acids or even acid salts, such as binoxalate of potash; but by proper treatment each may be obtained in a state of very approximate isolation, so far at least as coloured substances are concerned. The phyllocyanine of Fremy* is mainly the product of decomposition by acids of one of the green bodies, and is naturally a substance of a nearly neutral tint, showing however extremely sharp bands of absorption in its neutral solutions, but dissolves in certain acids and acid solutions with a green or blue colour. Fremy's phylloxanthine differs according to the mode of preparation. When prepared by removing the green bodies by hydrate of alumina and a little water, it is mainly one of the yellow bodies; but when prepared by hydrochloric acid and ether, it is mainly a mixture of the same yellow body (partly, it may be, decomposed) with the product of decomposition by acids of the second green body. As the mode of preparation of phylloxantheine * Comptes Rendus, tom. I. p. 405. |