FIG. 1. A NEW GARDEN PLANT (BARLERIA LICHTENSTEINIANA, NEES VON ESENB.). BY MAXWELL T. MASTERS, M.D., F.L.S. HIS is one of the most peculiar-looking plants we have ever had the fortune to see, and though it is destitute of the attractive colours which render so many of its fellow Acanthads such favourites in our stoves, it is very far from inelegant. The structure of the flowers, and the arrangements apparently intended to prevent cross-fertilization and to secure self-fecundation, invest it with additional attractions for the plant lover. We will first give a general description, and then allude to some of the more striking peculiarities of the plant. The shrub is covered over its whole surface with close, white, 1 "Fruticosa procumbens; spicis sessilibus secundis; bracteis dorsalibus ovatis incumbentibus, apice spinosis bracteolisque lanceolatis spinoso-dentatis; foliis ovato-oblongis spinoso-dentatis mucronatis petiolatis tomentosis; calycis laciniis exterioribus maximis late ovatis spinoso-acutatis dentatisque, 9-11 nervibus hirtis. Ad Grootrivier Prom, Bon, sp."-Nees von Esenbeck in D. C. Prod. xi. p. 235, 1847. hoary down. The branches are slender, virgate, sub-angular. The leaves are opposite, 1-2 inches in length or longer, linearlanceolate, entire, mucronate, with a central rib and numerous arched veins, tapering at the base into a very short stalk. The flower-spikes are axillary, 2-3 inches long, ovoid or oblong, consisting of a large number of closely packed overlapping bracts, all turned to the fore or lower part of the spike (second). Each bract is ovate-acuminate, mucronate, spine-toothed, 1-ribbed, with prominent and curved veins, and an inch to an inch and a half long. The calyx consists of four sepals in two rows; the two outer sepals are appressed, the posterior one, B, nearest the stem is suborbiculate, mucronate, spine-toothed, and ciliate, many ribbed, abcut an inch long; the anterior sepal, A, nearest to the bract is similar to the preceding, teeth smaller and unarmed; these two sepals project at the sides beyond the bracts, and completely hide the two inner sepals c, which decussate with the outer ones, than which they are much smaller (-inch long, one line broad), linear, spathulate, acute, ciliate, at the base. On the posterior side of the flower, between the two inner sepals, is a vacant space, apparently indicating the position of a fifth suppressed sepal. The corolla D is slightly larger than the inner sepals, of a brown colour, tubular, tube compressed from back to front, dilated at the base; its limb is divided into five short, ovate, erect, overlapping lobes, two external to the three others, and all so tightly appressed that they close the mouth of the corolla. Stamens 5, attached to the tube of the corolla a little below its mouth-2 fertile, 3 sterile; filaments erect, hairy; anthers of fertile filaments erect, adnate, sagittate, oblong, black, 2-celled-cells splitting lengthwise, and towards the centre of the flower. Pollen grains large, globose, reticulated. Ovary about two lines long, oblong-ovoid, compressed from back to front, 2-celled, with axile placentas: ovules 4, two in each cell, each orbicular, ascending, the lower one overlapping the upper Style cylindrical, ultimately longer than the corolla, curved at the apex, where it terminates in an obliquely truncated stigma. The fruit, which we have not seen, is described as tetragonal. one. The inflorescence, with its curious one-sided arrangement of bracts, resembles in general appearance that of some composite, as Carlina, but is lateral, not terminal. The construction of the flower seems to favour self-fertilization, as will be seen from the following facts: the two outer sepals are closely pressed together, so that it is not altogether easy to separate them; the edge of the larger of the two sepals is spiny, and the teeth would seem rather to deter than favour the access of insects. The corolla is completely concealed within the sepals, its lobes are also tightly appressed and clip the stigmatic end of the style, and prevent its passage from the flower, so that the stigma is always included. If young flower-buds be examined, the style will be seen to be erect and straight (G), but as the style lengthens and comes into contact with the lobes of the corolla, its further progress is arrested, it becomes curved (F), and in the fully developed flower, D, the style forms a complete loop, owing to the stigma being retained within the corolla. Such are the ap pearances presented by the flower, and the inferences deduced from them. We have had no opportunity of testing how far those inferences are borne out in practice. For specimens of this singular plant we are indebted to Mr. W. Bull. Fig. 1 shows a branch with the under-side of the inflorescence; fig. 2 shows the details of the flower. A and B are the two outer sepals, natural size, forced open, showing the erect flower in the centre; c represents the two inner sepals, separated, natural size; D shows the corolla, enlarged; E is a section showing the arrangement of its lobes; G and F represent ovaries, with the young style beginning to become curved.-Gardeners' Chronicle. want. Plumbago.-A Ceylon paper says, that if the world wants plumbago, and is willing to give a good price for it, Ceylon can supply the Fresh discoveries of the mineral are constantly made. Should mining continue at the rate of the past few years, Government will have to regulate the pursuit with reference to the safety of the people, otherwise lives will be lost from foul air and the collapse of badly formed pits. We observe that the Chamber of Commerce found the specimens of this mineral sent some time ago from Hambantotte to be defective, from the presence of " rust," or, as the natives call it, "water-mark." The progress of this staple export has been from 46,000 cwt. to, in round numbers, 200,000. The quantity has considerably more than quadrupled in five years, and more than doubled in the last as compared with the previous season. REVIEWS OF BOOKS. L'Homme Primitif. Par LOUIS FIGUIER. Ouvrage illustré de 30 Scènes de la Vie de l'Homme primitif, etc. Paris: Hachette. 1870.1 PARAPHRASING the Shakspearian exclamation, we may well say of M. Figuier, "Forsooth, a great" compiler! There is no subject in science which is too comprehensive or too intricate to stay the intrepid hand of the French populariser of scientific knowledge. Botany, Geology, Entomology, Herpetology have all been dealt with by M. Figuier, after M. Figuier's own fashion, and now he has laid hands on the hitherto sacred realm of prehistoric archæology, and, as a consequence, we have before us a huge and handsome volume, in which we must admit that scissors and paste have not been spared. But, as we have often had to say before, when speaking of M. Figuier's labours, we are dissatisfied with the result taken tout-entier. The illustrations, so far as they are confined to scientific objects, are excellent, and they are not less numerous than good; indeed, this part of the work is so very perfect, that pictorially a concise account is rendered of the gradual evolution of man from the savage to the civilized condition. When we come to examine the text, we are compelled to be far less complimentary to the author. It is not that there is not abundance of matter, and matter, too, which is often taken from very excellent sources, but it is the author's mode of digesting the facts of which we complain. M. Figuier is not a 1 The block from which the above illustration is printed was kindly lent by Messrs. Chapman & Hall, who are about to reproduce the work in English. savant, he is merely a scribe. His early training, if it was scientific, must have been given in a very bad school. Hence we find that preconceived ideas, irrationalism, prejudice, and dogmatic expression abound throughout his writing, and deprive his teachings of any value they might otherwise possess, in developing the minds of his readers. As mere records of scientific facts, the compilations of this author are in some respects of very high merit; and, as we have already said, in illustration they surpass the popular works of English and German writers; but as works calculated to inculcate a sound scientific method of reasoning from facts up to generalizations and laws, we'must say-and we should not be dealing conscientiously with our readers were we reticent on this point-that M. Figuier's works are the last we should think of putting into the hands of youth. It is a great and important responsibility, that which rests with the man who commends a work which may give a bias to the mind of youth, a turn which may lead it toward truth or from it, for ever; for "Just as the twig is bent, the tree 's inclined;" and feeling this, we cannot approve of M. Figuier's mode of dealing with opinions which, we will not say, he disbelieves, but which he dislikes. It is very easy to get rid of the theories of an adversary by saying that they are rubbish, and it is a method which M. Figuier affects to a very great extent; but it is one which is just as applicable to one side as to another, and it is one which utterly deprives a scientific work of any quality beyond that of being simply curious. To some persons this may seem unimportant; they will say, perhaps, that what we want are facts, and that the author gives us these. To this we should not object much did M. Figuier confine himself to facts; but as he proceeds to generalization, he should do so impartially, and he does not. But is not the whole aim of scientific teaching to lead us to inferences which shall convey some truthful idea of the laws of the universe ?-and we are sorry to think that in not a few instances M. Figuier's processes of argumentation are rather of the ex cathedrû type. There is, too, a little too much of self-glorification about the manner in which our author explains the nature of the task he has undertaken and the difficulties which encompassed it. It is not too much to say that it is simply an impertinence to Science to commence a preface in the following words, which we quote from M. Figuier's "fore-word": "J'entreprends ici d'exposer une Science qui n'existe pas encore. Les recherches concernant l'origine de l'homme sont déjà en nombre immense, mais elles n'ont pas été co-ordonnées avec suite et méthode. Personne jusqu'ici n'a entrepris de le débrouiller, et d'écrire un ouvrage lié, comme on le disait au dix-huitième siècle, sur tous les faits qui concernent l'homme aux premiers temps de son apparition sur la terre." Now, though in the end of the preface the author admits the existence of Sir Charles Lyell's Antiquity of Man and Sir John Lubbock's Prehistoric Man; and though in part of the work he refers to Keller's and Nilsson's treatises, it is quite clear that he regards these as books of a rather inferior order, and as being terribly uninteresting. This is inexcusable. But what will our English readers say when they read the following criticism, which M. Figuier, with all the audacity of flippant ignorance, passes on the classic volume of the greatest geologist in the world : "The treatise of M. Charles Lyell, upon the 'antiquity of man,' a French translation of which appeared in 1864, is but a series of technical descriptions of the deposits of the quaternary period, in which traces of man are found. There is no order in all these notes, so bizarrely grouped together. . . . . Such is this treatise on the 'antiquity of man,' which gives a singular idea enough of the way in which the English geologist prepares his works." .... As to the subject-matter of the work before us, it would be needless to enter upon an abstract of its contents. Suffice it to say that the author, following the scheme of division proposed by M. Lartet, describes seriatim the relics of [March 2, 1870. primitive man which have been discovered in various parts of the world. Thus, much in the same order as that followed by Sir John Lubbock in his Prehistoric Man, and in his excellent translation of Nilsson's Stone Age, M. Figuier describes in detail the weapons, habits, habitations, and cotemporaries of the men of the rough-stone period, the polished-stone age, the bronze and iron epochs. In all these descriptions he is, of course, Gallically terse, clear, and concise; in fact, his chapters are by no means dry reading, and as they contain a number of facts almost new to many readers, they will be found of great interest. We must, however, caution the reader against too readily accepting M. Figuier's assertions. Many of these are very questionable, and some are distinct mis-statements of fact. We cannot afford space for the correction of all the French author's errors; but we may point out a few, with the view of putting his readers on their guard. Let us take, for instance, the subject of the celebrated jaw-bone discovery at MoulinQuignon, with which the name of M. Boucher de Perthes is so memorably associated. Here is a somewhat rough, but, we think, not inaccurate translation of M. Figuier's version of this historical matter. "On the 20th of April, 1863, M. de Quatrefages announced to the Institute this discovery of Boucher de Perthes, and he presented to it the interesting specimens found at Abbeville. This intelligence produced a great sensation in England. The English savants who were especially occupied with this question, Messrs. Christy, Falconer, Carpenter, and Busq (sic)-came over to France, and, with M. Boucher de Perthes, examined the deposit containing the flint hatchets and the human jaw-bone, and 2 they unanimously confirmed the exactitude of the conclusion drawn by the indefatigable archoo. logist of Abbeville." This is one solitary specimen of M. Figuier's method of dealing with historical facts. Those who have read Mr. Busk's capital account of the jaw-bone in the Natural History Review,published shortly after the visit to Abbeville, are aware of the nature of the unanimity (!) alleged by M. Figuier, and they will remember how, by sawing the bone, Mr. Busk showed that the jaw was a recent one, which some clever workman had placed in situ and thus palmed off on the credulity of M. Boucher de Perthes, in a manner reminding one of Mr. Pickwick's well-known archæological investigations. M. Figuier's treatment of the Darwinian theory and the controversy of the Neanderthal and Engis skulls is equally satisfactory with his account of the Abbeville mare's-nest. He is quaintly humorous à propos of the supposed anthropoid character of the Engis skull, for he says, regarding the statement that the skull is a well-developed and high one : Hippocrates-Huxley says Yes, Galen-Vogt says No, and CelsusLyell says neither Yes nor No." Of the page plates which accompany the volume, and which are in true French artistic style, from the pencil of M. E. Bayard, we are bound to confess that the book would have been much better without them. One or two are fair and passable, the remainder, though cleverly drawn, are simply monstrous representations, and are ridiculous to the very acme of absurdity. The man represented in all is from the same model, and is of a type of beauty and expression such as might be selected for either a Jupiter or a Christ; the ladies are unusually pretty and piquant, and were their costume a little less décolletée they would recall to mind the faces at Cremorne or the Burlington Arcade; in a word, as samples of prehistoric mankind they are preposterous-not ideal, but, as artists would say, "idealized." One of the best illustrations in the volume is that of a Swiss prehistoric lake dwelling, which we reproduce on p. 223, but this is taken from the noble treatise by Keller. In conclusion, we can only express a hope that Messrs. Chapman & Hall, who are about to issue an English translation of this work, will take some steps to correct its mistakes and "blot out all its iniquities." 2 The italics are ours.-REVIEWER, BIBLIOGRAPHY. 1 ENGLISH. 8vo. 18s. 11s. cl. Anthropological Society of London: Memoirs, 1867-69. Vol. iii. 25s. Hill's Lunacy, its Past and its Present. 8vo. 3s. 6d. cl. FRENCH. Annuaire scientifique. Les Progrès des Sciences en 1869. Publié par PP. Dehérain, Professeur de Chimie, avec la Collaboration de MM. H. Blerzy, Docteur Brouardel, E. Dally, Gariel, etc. 9e Année, 1870. Paris. Charpentier et Cie. Aphasie syphilitique. Par le Docteur Benjamin Tarnowski. De la Crystallisation du Diamant, du Crystal de Roche et du Phosphate de Chaux basique par le Froid. Par M. Collas. Paris. Bureau du Journal Les Mondes. Diagnostic de la Gale. Par M. Anatole Manouvriez. Paris. Bonaventure. Dictionnaire encyclopédique des Sciences médicales. Directeur, A. Dechambre. Première Série. Tome ii. et iii. (ACH-AMP). Paris. Victor Masson et Fils. Du Chloral. Résumé de son Histoire chimique et thérapeutique. Par L'Année scientifique et industrielle, ou Exposé annuel des Travaux scientifiques, des Inventions, etc.: accompagné d'une Nécrologie scientifique. Par Louis Figuier. 14e Année (1869), contenant une Carte du Canal de Suez. Paris. L. Hachette et Cie. La Science et la Conscience. Par E. Vacherot (de l'Institut). Paris. Les Insectes auxiliares et les Insectes utiles. Par Henri Miot, Avocat. Paris. Librairie agricole, 26 Rue Jacob, Matériaux pour l'Étude des Glaciers. Par Dollfus-Ausset. Tome viii. 3e Partie. Observations météorologiques et glaciaires. Résumé et aide-mémoire. Paris. Savy. Saint Nazaire et la Question métallurgique. Par Henri Despecher. Paris. Renow et Maulde. Simples Lectures sur les Sciences, les Arts et l'Industrie, à l'Usage des Écoles primaires. Par M. Garrigues. Nouvelle Edition, entièrement réfondue. Par M. Boutet de Mouvel, Professeur de Physique et de Chimie. Paris. L. Hachette et Cie. Sur les Terrains jurassiques supérieurs en Algérie. Par M. Alphonse Pérou. Paris. Blot. Théorie et Démonstration du Mouvement perpétuel par la Force centrifuge. Par Gustave Huzar. Paris. J. Baudry. Traité de Calcul differentiel et de Calcul intégral. Par J. Bertrand, Membre de l'Institut, Professeur à l'École polytechnique. Calcul intégral. Intégrales definies et indéfinies. Paris. Gauthier-Villars. Zone à Avicula contorta et Infralias dans le Midi de la France, à l'Ouest du Rhône (Ardêche, Lozère, Aveyron, Hérault). Par M. Louis Dieulafait. The "London" Mounting Solution.-Mr. Sanford, of Red Lionsquare, has, says the British Journal of Photography, forwarded to us a sample of a new print mountant, bearing the name at the head of this paragraph. It is semi-fluid in a very warm room, becomes thoroughly liquefied when placed in a vessel of moderately hot water, but at the normal temperature of the present month it is quite gelatinified. A special advantage of this preparation is, that prints may be mounted on any kind of paper with entire freedom from cockling. Since we got the sample of the "London Mounting Solution," we have used it on several occasions, and always with undiminished pleasure, THE SOCIETY OF ARTS' LIBRARY.-From W. LLOYD WISE. SIR, Some months back I drew attention to the inconvenient arrangement of the Society of Arts' Library, and suggested a way of improving it. The letter signed "A New Member in the Society of Arts' Journal shows that my complaints were well founded, and that my suggestion as to improvements was at least deserving of some consideration. I have since written to the editor of the society's journal, but for some reason best known to those "in office," neither of my letters has been published. Under these circumstances I subjoin a copy of my last letter in the hope that you will favour me by its insertion in your valuable journal, and perhaps save some of your readers from being disappointed, as "A New Member," myself, and others have been. W. LLOYD WISE, M.S.A. Chandos Chambers, Adelphi, W.C., February 23. Your obedient servant, "To the Editor of the Society of Arts' Journal. "Sir,-I have been much interested by the letter of A New Member' in your last issue, and I quite agree with the suggestion that the society's operations have now assumed a magnitude which demands the occupation of more commodious premises. But as 'Rome was not built in a day,' neither can the society expect to find new premises exactly suited to its present purposes at a moment's notice. "I would not for an instant damp the energies of those who are disposed to exert themselves to secure a better building; but I contend that, in the mean time, we should make the best of the one we have, which, as a matter of fact, and as I have frequently pointed out, is not being done. "Your correspondent says, 'I have more than once or twice wanted to consult the library, but the library itself is used as a sort of exhibition room for models and pictures, and though it is no doubt desirable to have exhibitions, it is scarcely fair to do so at the expense of the utility of the society in other ways. The reading-room is partly an office, and partly a reference room, so that quiet study is out of the question. I joined the society, not from a purely philanthropic motive, but from a desire to avail myself of the advantages it offered, content, however, if a portion of my subscription went towards the general good. I feel somewhat that the society had no right to ask for my membership, if it could not accommodate me.' "How well do these remarks tally with the following passages which I extract from my letter of 9th September last, to the Times, viz., 'But anybody who may join in the hope of finding the library as serviceable as might reasonably be expected from an influential society professing to do so much in promoting technical education, and so forth, will be, as I have been, sadly disappointed.' "Although there is a fine room available, it has been thought proper to lumber it up for years past with a lot of old and dirty models and scraps of metal in glass cases, which in their present state and posi tion, can be of no use to anybody.' "And now I come to the question of what should be done to make the most of the society's present house, pending the appearance of a new house.' "To begin with, the society appears to be attempting too much for its present resources, and in so doing, is actually neglecting one of the first duties to its members,-that is, to provide every accommodation in the library. "At present the exhibitions and the library are alike failures, because there is not the convenience required for both: hence it is clear that one of the two things should be abolished for the present; it is equally clear that this must not be the library. The general importance of the library demands that it should take precedence over the 5 The answer to Dr. Beddoe is: From the context.-Reviewer, other matters which are now permitted to render it comparatively useless, and therefore I suggested months ago that the large room on the ground floor, which is at this time neither one thing nor another, should be converted into a commodious library and reading-room, which would be a credit to the society, and a real convenience to its members.' The present cumbersome glass cases might be either modified or superseded by other cases of a more suitable kind; and although the details of the alterations might require some little consideration, yet there can be no doubt as to the practicability of adapting the large room on the ground floor to suit the requirements of those members who may desire to use the library. It may be said that the present cases have been costly, and, furthermore, that the proposed alterations would involve some little expenditure; but although this may be so, common sense will dictate the expediency of expending a few pounds to save an old and influential society from that utter disgrace which a continuance of the present state of things must inevitably bring down upon it "Your obedient servant, "W. LLOYD WISE." TRANSIENT HEMIOPSIA. SIR,-Having read with interest, in SCIENTIFIC OPINION, Feb. 23, your report of Mr. Hubert Airy's paper "On a Distinct Form of Transient Hemiopsia," and having myself been subject to very similar attacks between the ages of 12 and 17, and once at the age of 36, I feel it not improbable that my own experience may tend to elucidate the subject, and possibly suggest relief from suffering. The blindness would come on quite suddenly; more than once while looking at a tablecloth woven with scarlet and blue; often while dressing for breakfast, when a portion of the left side of my face would disappear in the glass. The obliterating mass appeared to me like overlapping black bubbles, occasionally tinged with gold, but always rolling and growing outwards to the right, till every object had lost its left half. This would continue from 15 to 20 minutes, when it passed off, and was succeeded by 8 hours of intense headache, with nausea, numbness in the hand, and the greatest difficulty in expressing myself. If I sang, I had to practise over what I had to say in order to be understood, as the syllables would come wrongly strung together. Hoping to shorten suffering, I had been in the habit of immediately taking an emetic, but this appeared to make the attacks more frequent. Once, feeling very cold during the blindness, I drank a cup of strong ginger-tea, and for the first time no headache at all followed. Instead, therefore, of lying down in a darkened room, I went about my usual occupations, but discovered that the numbness and the difficulty of speech were still present, which surprised me, as I had always attributed the latter to the effect of severe pain. In succeeding attacks I always resorted to ginger-tea, with invariably the same result. I have known hot pickles succeed equally well in other cases. A. R. ASSUMING THE NAME OF SOWERBY.-From C. SOWERBY. SIR,-An advertisement has appeared in SCIENTIFIC OPINION in which it is stated that I "have assumed the name of Sowerby." Allow me to inform you that the business of my late father, G. B. Sowerby, has been in my possession since 1853; and in 1856, I became the owner of it by purchase. As the statement of which I complain is utterly devoid of truth, and likely to do me a great injury in my business, I shall feel obliged by the insertion of this letter. I am, Sir, your obedient servant, London, Feb. 27. C. SOWERBY. A New Insecticide.-M. Cloez, who is engaged at the garden of the Paris Museum, has invented what he considers a complete annihi. lator for plant-lice and other small insects. This discovery is given in the Revue Horticole, with the endorsement of its distinguished editor, E. M. Carrière. To reduce M. Cloez's preparation to our measures, it will be sufficiently accurate to say, take 34 oz. of quassia chips, and 5 drachms of stavesacre seeds, powdered. These are to be put in 7 pints of water, and boiled until reduced to 5 pints. When the liquid is cooled, strain it, and use with a watering-pot or syringe, as may be most convenient. We are assured that this preparation has been most efficacious in France, and it will be worth while for our gardeners to experiment with it. Quassia has long been used as an insect-destroyer. The stavesacre seeds are the seeds of a species of larkspur, or Delphinium, and used to be kept in the old drug stores. Years ago they were much used for an insect that found its home in the human head, but as that has fortunately gone out of fashion, it may be that the seeds are less obtainable than formerly. The stavesacre seeds contain Delphine, which is one of the most active poisons known, and we have no doubt that a very small share of it would prove fatal to insects. SCIENTIFIC SOCIETIES. Secretaries of Societies will oblige us by regularly forwarding "Abstracts of Proceedings; " and they would do much to enhance the interest and success of their meetings if they would enable us to publish in anticipation "notices of papers to be read," ROYAL SOCIETY. THURSDAY, FEBRUARY 24TH.-The following papers were read:"Note on certain Lichens," by John Stenhouse, LL.D., F.R.S., &c.— Through the kindness of W. Carruthers, Esq., of the Botanical Department of the British Museum, I obtained a considerable quantity of lichens from the neighbourhood of Moffat in Scotland. These were Cladonia rangiferina, and a mixture of Usnea barbata and Evernia prunastri, the latter of which were carefully separated by picking—a somewhat tedious operation, as they were much interlaced. Usnea barbata.-In order to extract the usnic acid from this lichen, it was macerated for about thirty minutes with a dilute solution of sodie carbonate, squeezed, again treated once or twice in a similar manner, and the turbid solution precipitated by a slight excess of hydrochloric acid. The crude dark-green acid thus obtained was mixed with milk of lime and a considerable quantity of warm water (40° C.), filtered, and the clear lemon-coloured solution of usnate of calcium acidulated with hydrochloric acid. The acid was thus precipitated in pale yellow flocks, which were collected. The reason that I adopted this modification of the process I formerly proposed,' is, that although usnic acid readily dissolves in milk of lime when it has been extracted, yet in order to exhaust this and other compact lichens, it requires to be treated a great many times if lime be employed, whilst two or three are sufficient with carbonate of sodium. The partially purified usnic acid obtained in the manner above described, was easily rendered quite pure by taking advantage of the peculiar property which this acid possesses, of forming an insoluble calcium salt when boiled with lime. The crude yellow acid was placed in a flask with a quantity of water and an excess of slaked lime, and the mixture boiled for twenty minutes or half an hour. The insoluble calcium usnate was collected, well washed with hot water, and the lime then removed by boiling it with a slight excess of hydrochloric acid. The tolerably pure usnic acid was then collected, and well washed with boiling water. It was advisable to continue the digestion with hydrochloric acid for half an hour, as it rendered the acid more compact and easy to collect. By this alternate treatment with lime and acid, a large quantity of some dark-coloured impurity was removed. This forms the best process for recovering usnic acid in a state of tolerable purity from residues. It was found, however, to be better, when considerable quantities of usnic acid were to be prepared, to boil the pale yellow usnic acid paste, as obtained by precipitation from the lime solution, with a small quantity of water, to which strong caustic soda solution was gradually added, sufficient to dissolve nearly the whole of the usnic acid. It was then set aside to crystallize, and when cold the very dark-coloured supernatant mother-liquor decanted, and the crystals of sodic usnate washed once or twice by decantation, with a small quantity of cold water. It was then redissolved and recrystallized once or twice in the same manner. The nearly pure sodic usnate was now dissolved in a considerable quantity of hot spirit, filtered, and the boiling solution strongly acidu lated with acetic acid. The usnic acid then separated in fine needles, which when cold were collected, well washed with cold spirit (in which they are almost insoluble,) and recrystallized from boiling spirit to render them quite pure. When the quantity of acid operated on was but small, the best means was to dissolve it by means of caustic soda solution in a large quantity of boiling spirit, filter from the insoluble impurities, and strongly acidulated with acetic acid. The nearly pure usnic acid which crystallizes out in large needles when the solution cools, was collected, washed, and recrystallized two or three times from spirit. I. 130 grm. usnic acid gave 298 grm. carbonic anhydride and ·060 grm. water. II. 245 grm. usmic acid gave ·564 grm. carbonic anhydride and 188 grm. water. |