PART FIRST. Analytical and Critical Reviews. 1. Treatise on the Oleum Jecoris Aselli. By JOHN HUGHES Bennett, M.D., &c. Edinburgh, 1841. pp. 180. 2. On the use of Cod Liver Oil. By C. J. B. WILLIAMS, M.D., F.R.S. 3. First Medical Report of the Physicians to the Brompton Hospital, 4. L'Huile de Foie de Morue, envisagée sous tous les Rapports, comme Cod Liver Oil considered in all its bearings as a Therapeutic Agent. By 5. On the Changes produced in the Blood by the Administration of Cod Liver Oil and Cocoa Nut Oil. By THEOPHILUS THOMPSON, M.D., F.R.S. (Proceedings of the Royal Society,' vol. vii., No. 3, 1854.). 6. Third Lettsomian Lecture on Medicine for 1854. By Dr. T. THOMP- SON. (Delivered before the Medical Society of London.) 7. On Cod Liver Oil. By JONATHAN PEREIRA, M.D., F.R.S. (Phar- maceutical Journal,' vol. viii., 1849.) As it may be a matter of doubt whether there is any remedial agent 33-XVII. 1 proposer to refer effects to their proper causes, partly from a desire of gaining popularity, even at the expense of strict integrity; these having acquired some ephemeral reputation, when brought to the test of experience are found worthless, and sink into merited oblivion. Cod liver oil, however, cannot be classed amongst such agents, for instead of losing, it daily gains reputation, and has already stood the severe ordeal of extensive clinical observation. It appears to us, therefore, desirable to lay before our readers, in a condensed form, the principal points that have been really made out with regard to the origin, varieties, composition, and therapeutic action of this drug; and the more so as conflicting opinions seem to exist, not as to the value of the remedy itself, but as to the comparative efficacy of the different varieties of this oil now found in English commerce. Among the works at the head of our article is one by Dr. de Jongh, which we shall have most frequent occasion to allude to, owing to its giving a résumé of the whole subject. At the same time, we think it right in this place to remind our readers that much relating to the history and preparation of cod liver oil, up to the time of its publication, will be found in Dr. Bennett's work, as also considerable information regarding the opinions which have been held in reference to the action of the drug upon the human economy, and the diseases for which it has been given with the greatest success. In his preface, Dr. de Jongh states, that although his present work has been modelled upon a preceding one published by him in 1843, under the title of Disquisitio Comparativa Chemico-Medica de Tribus Olei Jecoris Aselli Speciebus,' yet, in fact, with the exception of the chemical analysis of the three commercial species of cod liver oil, it has been almost entirely re-written, and may be considered as a complete monograph upon the subject of which it treats. The work is divided into four parts. In the first, the history of the medical employment of the oil, and also the progress in its chemical analysis, is detailed; in the second is given an account of the origin and preparation of the different kinds of oil; the third part is devoted to its chemical analysis, and the adulterations to which it is subjected; and the fourth to the value of the drug as a therapeutical agent, its mode of action, and also the kind most advantageously employed. From the history we gather that in very remote times fish oils have been medicinally employed; that according to Pliny the Romans used oil from the dolphin, both internally and externally; that seal and whale oils were likewise reputed remedies; that Pliny himself recommended the oil obtained from the liver of the Gadus lota, or Burbot, under the name of Liquor mustele fluviatilis hepaticus, &c. As to cod liver oil, it appears to have been used from time immemorial in Sweden, Norway, Holland, and Germany, as a popular remedy for chronic gout and rheumatism, but not to have been prescribed by physicians before 1766, when it was used at the Manchester Infirmary. The remedy, however, was not at all extensively administered in this country till 1841, when Dr. Bennett's work made its appearance; and even for several years after that time, its use was almost limited to chronic rheumatism and scrofulous affections; it was not till the publication of the paper by Dr. C. J. B. Williams, in the London Journal of Medicine,' in 1849, On the Use of Cod Liver Oil in Pulmonary Consumption, that it became generally employed, although various papers by Dr. Thompson, Mr. Chalk, and others, showing its efficacy in phthisis, had appeared in the different medical publications. In France, its general adoption was still later than in England; but in Belgium, Holland, and in some parts of Germany, its use was of an earlier date. We must, however, refer such of our readers who may desire full information on the history of cod liver oil, to the works of Drs. Bennett and De Jongh. With regard to the progress of its chemistry, the following short summary may suffice, as most of the results obtained until within the last few years are now interesting only as matters of history. In 1822, M. Wurtzer separated, both from the brown cod liver oil and ordinary fish oil, a yellow watery extract, with disagreeable odour and bitter taste, but did not proceed further with the analysis. In 1828, M. Spaarmann found stearic (margaric) and oleic acids, together with phocenic acid, and a colouring and aromatic matter. In 1830, M. Marder made a more elaborate analysis of the oil, and besides margaric and oleic acids and glycerine, described the existence of certain resins, colouring matters, salts, and gelatine. In 1836, iodine was suspected by M. Kopp, and discovered in the oil by M. Hopfer de l'Orme, and this discovery was subsequently confirmed by many other chemists. After this, bromine was found to be a constituent by M. Herberger, and phosphorus in an unoxidized state by M. de Vry. The other important additions to our knowledge of this substance are chiefly due to Dr. de Jongh, and will be fully described as we proceed. On the origin and preparation of Cod Liver Oil.-Oleum morrhuæ, according to the London, Dublin, and United States Pharmacopoeias, is the oil derived from the liver of the common cod fish (Gadus morrhua, or Morrhua vulgaris); but in commerce it may be considered as including not only the above oil, but also that derived from the various species of Gadus, as the Gadus callarias, Gadus carbonarius, &c. &c. De Jongh classifies the most important of these, in a medical point of view, as follows: Gadus morrhua, or Asellus major, the common Cod-fish; found in large quantities on the coasts of England, France, Iceland, and Norway, but especially off Newfoundland. Gadus callarias, or Asellus striatus, the Dorse; found largely on the Norwegian coast, and principally near the Lofoden Islands. Gadus molva, or Asellus longus, the Ling; found also on the coast of Norway, though less abundantly than the above two species. Plentiful near England. Gadus carbonarius, or Asellus niger, the Coal-fish; inhabiting the same localities as the last. Gadus pollachius, or the Pollack; found in Norway, especially near Tromsoe. Gadus merlangus, or Asellus albus, the Whiting; inhabiting the coasts of England and France. Besides many other species of less importance. De Jongh then gives various accounts of the early methods employed at different places for the preparation of cod liver oil, which resemble each other more or less; amongst these we may mention the account given by M. Tiedemann, who states that there are four sorts of genuine oil, which are thus obtained:-the livers are packed in tall vats, furnished with three taps, placed at different heights, and then exposed to the sun, which favours the separation of the oil. On opening the upper tap, a pale oil is obtained; from the middle one, a light brown; and a darker brown, yet transparent oil from the inferior. These three are for medicinal use; by pressure, however, of the remaining mass of livers, a very dark and thick product is separated, which is made use of by curriers. Finding that much obscurity existed, both as to the sources of the different oils and to the modes of preparation, Dr. de Jongh endeavoured to clear up the subject, and for this purpose made the following inquiries of M. Konow at Bergen, and of M. Mack of Tromsoe : 1. What fish are used in the preparation of cod liver oil? 2. How are the three species, known on the Continent by the names of the pale, brown, and black oils, prepared? 3. Are these three kinds of oil prepared from the livers only? The answer received from M. Konow was to this effect. That the Gadus callarias, or Dorse, was principally made use of in the preparation of the oil. That the fishery was, chiefly during the winter time, near the northern coasts of the Lofoden Islands. That after the fish were landed, the livers were separated and heaped in vats or tubs, and there left to the end of the fishery. When the fishery went on regularly, a very pure, pale, and limpid oil was commonly obtained; but when the conditions were reversed, the oil did not possess the above properties. At the conclusion of the season, the oil which had separated from the livers was decanted and put into kegs, and formed the "pale oil" of commerce. Afterwards, the livers were submitted to the action of heat, and a black oil obtained; the brown oil resulting either from the pale oil being left too long in contact with the livers, or kept too long after its separation. That the more oil contained in the livers, the better the product. That the Gadus carbonarius, or Coal-fish, yielded a clearer pale oil than the dorse; but the black oil obtained from that fish was thicker. That the coal-fish oil was considered less efficacious as a therapeutic agent; it was, however, often mixed with dorse oil. And, lastly, that not unfrequently other oils, commonly from some species of Gadus, but sometimes from the seal and other Cetacea, were often mixed with the true oil, and when so were very difficult to be distinguished. The substance of the answers received from MM. Mack of Tromsoe was to the effect, that in commerce there were three fish liver oils, from the dorse, the coal-fish, and the pollack; that from the first being by far the most important article of commerce. Dorse oil is thus obtained:-The livers are placed in vats, and left till decomposition ensues. A large quantity of oil separates, which, when collected, forms the "pale oil;" the remaining livers are then heated in iron boilers, from six to twenty hours, and yield a dark-brown oil, known as the "black oil" of commerce. Coal-fish oil is prepared in the same manner, the pale and dark oils obtained differing from those of the dorse, in congealing very readily when exposed to cold. Pollack oil, both pale and black, is also obtained as above described; but as the livers of this fish, which are more greasy than those of the dorse and coal-fish, decompose less readily, they are heated when still comparatively fresh, and then yield the "brown oil" of commerce. The brown oil from the dorse and coal-fish results either from the pale oil being left too long in contact with the livers, or, a pale oil having been first separated, the second yield possesses these properties. MM. Mack assert that the livers of the fish are the only parts employed in the manufacture of the oil. Dr. de Jongh thinks that from these two independent sources of information, we may conclude, as far as the Norwegian oil is concerned— 1st. That the fish made use of are the Gadus callarias and the Gadus carbonarius, chiefly the former. 2nd. That the pale oil flows from the livers when they have undergone a certain degree of putrefaction. 3rd. That the brown oil owes its colour either to prolonged contact with the livers, or from being afterwards kept too long. 4th. That the black oil is obtained by heating the livers after the separation of a large quantity of pale oil. 5th. That the livers only of the fish are employed in the manufacture. He explains the slight discrepancy which will be noticed in the two accounts regarding the brown oil, by the circumstance that it is only lately that the Gadus pollachius has been used as a source of oil, and the liver not readily putrefying, heat is often employed earlier in the process. Dr. de Jongh afterwards speaks of his visits to England in 1849, and also in 1851, for the purpose of ascertaining the kind of fish made use of, and the methods employed in the manufacture of the oil used in this country. He states that in 1849 most of the druggists in London prepared their oil by boiling the livers of the Gadus morrhua, or common cod-fish, in water, and afterwards separating the oil from the surface, and filtering it from any albumen or cellular tissue mixed with it; but that some made use of steam heat only, applied outside the vessels containing the livers. By either process, fresh livers being used, an almost colourless oil, and one devoid of taste and odour, is obtained. We may here state that the liquid process is not at present employed in this country, but that the best English oil is thus prepared :—The livers are collected daily, so that no trace of decomposition may have occurred, carefully examined, in order to remove all traces of blood and impurity, and to separate any inferior livers; they are then sliced, and exposed to a temperature not exceeding 180° Fahr., till all the oil has drained from them. This is filtered, afterwards exposed to a temperature of about 50° Fahr. in order to congeal the bulk of the margarine, and again filtered, and put into bottles well secured from the action of the air. Messrs. Bell and Co., we know, effect this separation of the solid fat; we believe, however, that this is not done by all the English manufacturers. Of course an oil thus prepared is less tender, or remains fluid at a lower temperature, than any other. De Jongh states that in 1850 the oil used medicinally in this country |