6 Lectures on Chemical Philosophy. CHEMICAL NEWS, nearly parallel, and very close to each other. Schicken- these bodies identical, not merely isomeric With refer danz, who determined the solubility of hydride of ethylence to Professor Wanklyn's remark, he felt it impossible in water, thinks that it would appear probable that this to acknowledge continually the prior labours or steps in relation between the coefficients of absorption of the two an investigation already ascertained by other experi gases was not accidental, but might be attributable to their mentalists. It was not necessary at the present time, and chemical constitution as isomeric bodies. The author positively inconvenient, to have always to mention believes that the slight difference in the solubility and the Bechamp's name in connexion with the admirable process parallelism of the two curves may easily be accounted for of reduction with acetic acid and iron filings, which by the existence of impurities in the methyl employed by chemists had already given him the credit of having Bunsen, which was prepared by the action of zinc upon originated. iodide of methyl, a method which yields the least pure Sir BENJAMIN BRODIE having inquired whether any product, and even a small admixture of a foreign gas difference in constitution was supposed to exist, whielt, cannot fail to exercise a considerable influence on the would account for the discrepancies regarding the chlorme. value of the coefficients. In alcohol the two gases are substitution products? also soluble in the same proportions, and hence the author believes himself justified in asserting "that until differences are found between methyl and hydride of ethyl better marked than those above mentioned, we must consider the hydrocarbons, C2H, derived from different sources, as identical, and as being hydride of ethyl or deutyl." The PRESIDENT considered the author's communication to have an important bearing upon the theory of radicals. The results so far were mainly of a negative character. One proof of identity had been brought forward; but otherwise there did not appear to be any difference between the chemical properties of methyl and those of the hydride of ethyl. Dr. FRANKLAND did not allow the author's experiments to be conclusive, especially those relating to the production of the normal chloride of ethyl in the presence of water. Dr. Kolbe and himself had investigated the action of potassium upon the cyanide of ethyl, and the results were exactly in accordance with the published statements just now called in question by Mr. Schorlemmer. Further researches were required before the identity or isomerism of these bodies could be determined. For himself, he believed they were not identical, but only isomeric. Mr. C. H. GREVILLE WILLIAMS said that this class of investigations was attended with the greatest possible difficulty; and it behoved us to suspend our judgments. Amongst the products of the destructive distillation of Boghead coal were several substances having the same composition and boiling point (excepting butyl), and giving similar nitro-compounds with fuming nitric acid. Recent investigations of the tertiary monamines of the picoline series had led him to the conclusion that the lutidine derived from the destructive distillation of quinine is not the same as the lutidine of Boghead naphtha. Professor WANKLYN would have been glad to know whether the chlorine substitution product obtained by Mr. Schorlemmer was the veritable chloride of ethyl. It might have been but an isomer. Ethyl boils at 20o C., whilst hydride of butyl, which is absolutely identical with it in composition, boils at about zero; thus showing a considerable difference of 20°. In a similar manner the hydride of hexyl obtained from mannite is only isomeric, but not identical, with that prepared from Boghead coal. An interesting fact had recently been made known by Carius, to which reference should have been made in the author's paper-viz., that, by acting upon ethyl with bromine, the bibromide of butylene was produced. Again, to Cahours and Pelouse was due the generality of the method of investigation followed by Mr. Schorlemmer; and he considered that this circumstance should have been acknowledged by the author. Dr. ODLING thought great praise was due to Mr. Schorlemmer for having upset the only point which has hitherto been relied upon as establishing a difference between methyl and the hydride of ethyl. The difference in their coefficients of absorption was really so slight as to be easily accounted for by variations in the degree of purity of the substances. The author had a full right to adopt an opinion contrary to that of Dr. Frankland, and to consider Dr. FRANKLAND Wrote upon the board the formule undermentioned, and he believed it possible that in one example the chlorine replaced an atom of hydrogen forming past of the radical, and in the other instance attacked only one of the outstanding atoms of hydrogen, thus Methyl product. Chloride of ethyl CH2CI H H CH Professor WANKLYN suggested there might then be twenty-four possible combinations. Mr. 14 The PRESIDENT then called upon the Secretary to read a paper "On the Action of Baryta on Suberic Acid, Richard Dale, of Owen's College, Manchester. The author commenced by referring to the hydrocarbons C6H14 and CH18 boiling at 76° and 125° C respectively, and stated that his experiments had for their object the isolation of an intermediate number of this group, By the action of nitric acid on castor oil, suberic acid CHO and azelaic acid, C,H1604, were conjointly produced. The ether, in which the latter was more soluble. The suberle white powder resulting from this action was treated with acid was obtained in needle-shaped crystals, and the azelaic acid in pearly white scales. From two and a half kilogrammes of castor oil 90 grammes of suberic acid and 75 of azelaic acid were obtained. The acids and silver salts were analysed, and when azelaic acid was distilled with baryta, the hydride of heptyl, boiling at 99 C (Schorlemmer) was obtained. The remainder of the evening was devoted. to the de scription of "Vacuum Experiments," by Dr. Hermann Sprengel, which will be given in our next. The meeting was then adjourned until the 30th June. LECTURES ON CHEMICAL PHILOSOPHY. Delivered at the College of France, by M. A WORTZ. [THE course of lectures recently delivered by M. Warr has been devoted to the exposition of modern theofies in. chemistry, and we have thought that their reproduction here in abstract would be of interest to our readers who seek for a lucid explanation of recent ideas.]. In the present course of lectures I propose to expound the chemical theories which have of late years directed the investigations of many experimenters, and which are now beginning to prevail. I shall endeavour to do this with the modesty belonging to a savant, and with the respect which is due to the opinions of others. I know that our theories are subject to variation, growing with the progress of knowledge, and sometimes only the expression of a momentary want. But I know, also, that theory is the soul of science, the torch of experiment, and that from it has proceeded what we call the new chemistry Strictly speaking, there is no new chemistry. In the development of chemical ideas there have been no sudden changes, no violent subversions, in a word, no revolutions. Chemistry, since Lavoisier, has been in a state of continued steady progress. But things have not essentially changed; CH, and O. Ordinary acetic acid he supposes a comthe chemistry of to-day is only a continuation of the che-pound of acetic anhydride, CHO, and water, H2O; that mistry of the beginning of the century. All the modifica- is, an hydrate, a salt, composed of acid and base. Sultions accomplished since Lavoisier have been produced by phuric anhydride again, SO, combines with water, H2O, to rational experiment, the influence of which is necessarily form sulphuric acid, SO,H2O,—a binary compound, an permanent. To enlighten ourselves on this point let us hydrate, in fact. endeavour to follow the progress of the theory of the science from Lavoisier's time to our own. Positive chemistry arose from an attentive study of the phenomena of combustion and the constitution of salts. It was observed that the calcination of a metal was nothing less than the combination of the metal with oxygen, the formation of an oxide, in fact. It was seen, also, that acids result in general from the addition of oxygen to another substance. At last it was proved that salts were easily formed by the union of an acid and an oxide. Other observations confirmatory of the preceding were made, and in time it was said that all salts were binary-that is to say, compounds of an acid and a base; or to express it more generally that every compound system could be divided into two more simple antagonistic systems. That was the foundation of the edifice raised by Lavoisier. That was the base of dualism. The labours of those who immediately followed the founders of chemical science, the discoveries of the composition of the alkalies and the elementary nature of chlorine; the discovery, also, of the composition of cyanogen, which, notwithstanding its complex nature, formed binary compounds exactly like the binary compounds of chlorine, &c.-all these facts appeared a striking confirmation of the ideas of Lavoisier. Berzelius, by discovering the double chlorides and double sulphides, which he named chloro-salts and sulpho-salts, contributed to strengthen these ideas. He did more than this; he attempted a theoretical explanation of dualism, and published an hypothesis which has had a great success-the electro-chemical theory. We know that bodies combine in definite proportions, and sometimes in multiples of those proportions. We know, also, that Dalton, to explain this general law, supposed the existence in every simple body of small indivisible masses or atoms, each having a particular weight -the atomic weight; and that compound bodies are formed of these atoms placed in juxtaposition. Berzelius seized on the idea of the atoms, and supposed each to have two poles in an opposite electrical state. In some atoms positive electricity predominates, in others it is the negative. Bring two atoms in opposite electrical states together, and they attract each other and unite. Suppose three or four of them, they will always constitute two antagonistic groups, so that the resulting compounds will be constantly binary. Such was the theory of Berzelius. The only proof of the truth of this theory Berzelius required was the action of a current upon chemical compounds. Chloride of potassium, for example, decomposed by the current into two simple bodies, chlorine and potassium; sulphate of potash is also decomposed into potash and sulphuric acid, the metallic group going to one pole and the non-metallic to the other. Endowed with a grand imagination, Berzelius succeeded in bringing all the great discoveries in chemistry up to 1830 into agreement with his ideas. Thus when Chevreul published his remarkable investigations on fatty bodies, and showed that fats are neutral bodies composed of glycerine and a fatty acid, Berzelius contended that glycerine was an oxide of lipyl. In the same way he explained the discoveries of Dumas and Boullay on the compound ethers. These, said he, are compounds of an acid with oxide of ethyl, CHO. Acetic ether, for example, contains C1H ̧О ̧ + С‚Í‚O, just as sulphate of potash is SO3 + KO. The remarkable results obtained by Liebig and Wöhler with the benzoilic compounds were explained in a similar way. Thus, we see that up to 1830 chemists in general sought to apply to organic bodies the current ideas on mineral chemistry. But now from 1834 a change begins. A great discovery has been made. Dumas and Laurent have found that chlorine, an electro-negative body, may be substituted for hydrogen, an electro-positive body; that is to say, chlorine may be combined otherwise than by molecular additionin other words, by substitution. Chlorine may be substituted for hydrogen, equivalent for equivalent. This was afterwards confirmed, and the researches were extended by Laurent, Gerhardt, Malaguti; but the first announcement by Dumas of the discovery and its consequences was sufficiently precise to disconcert any other chemist but Berzelius. He not only refused to modify his theory, he even pretended that dualism was not affected, and laughed at the theory of substitutions. Let us see how he disposed the notation of some organic compounds. Formic acid, for example, CH4O4, is formed of a radical, C2H2O, and water, H2O; it is a binary compound, a couple. Chloroform, which, according to Dumas, is only the result of the substitution of 3 Cl for 3 H in C2H, and which may therefore be represented as C2 (HCI), chloroform is according to the dualist a compound of the radical C2H, and 3 Cl. Trichloracetic acid is also represented in the system by the binary symbol [C2H3+ C2C13] + H2O. Such is the dualistic system of Berzelius, and every one will admit that supposing the experimental starting point to be correct, such deductions must always have been rash and hypothetical. But, as we shall proceed to show, the starting point was not correct. There was, then, an urgent need of a chemical theory at once more comprehensive, more positive, and more rational than that of Berzelius. We shall see it born, and slowly develope itself. Dumas, taking experiment and rigorous induction as his sole supports, was led to represent acetic acid as CHO, and trichloracetic acid as C. (H2Cl ̧) O. Having observed, in fact, that the chemical properties of the chlorinated acid are completely analogous to those of the ordinary acid, and that the quantity of hydrogen which disappeared was exactly equivalent to the quantity of chlorine substituted, he naturally concluded that if CHO, is the experimental expression, so to speak, of the normal acid, C. (HCl) O, is that of the chlorinated acid. In other words, said he, trichloracetic acid belongs to the same type as acetic acid. This was the origin of the theory of types. Dumas at first believed in two kinds of types; the chemical type of which he was himself the author; and the mechanical type, the first idea of which was started by Regnault. Compounds belonging to the chemical type are those which contain the same number of atoms similarly united, and whose fundamental chemical pro 8 Academy of Sciences-Notices of Books. perties are identical. Compounds belonging to the mechanical type are those which while containing the same number of atoms present dissimilarities in the chemical characters of their products of metamorphosis. We mention the latter only for the sake of historical accuracy In what follows we shall speak only of chemical types. At first the theory of types was only applied to the hydrogenated compounds of carbon, and their oxygen, chlorine, and bromine, &c., derivatives by substitution. There was a great number of types, and they only included a small number of compounds. But thanks to the researches of Laurent, Williamson, and especially of Gerhardt, the theory of types was at once simplified, and, moreover, received an indefinite extension. It was Laurent who first showed that oxides are exactly analogous to hydrates; that the one and the other only differ from water by the substitution of one or two atoms of metal for one or two atoms of hydrogen: that, for example, if we represent water as H2O, caustic potash is (KH)O, and oxide of silver AgO. Thus he inferred that water is the type of oxides Then came the experiments of Williamson on etherification, which showed that hydrate of ethyle was nothing more than water, {CHEMICAL NEWS, July 2, 1864. This is the foundation of the theory of types of which Gerhardt is the author. It bears the stamp of his genius, and is at once simple and fruitful. Since his time, and by the hands of other chemists, discoveries have succeeded discoveries with a rapidity until now unknown in the history of sciences; organic chemistry has received an unimagined extension, and that gift of foreseeing which is the characteristic of rational progress has been greatly developed. (To be continued.) ACADEMY OF SCIENCES. THE proceedings of the last meeting of the Academy offer but little of interest to chemists. Dr. Hofmann contributed a paper, entitled "Facts Re.. lating to the History of the Colouring Matters Derived from Coal- Tar." In this paper he describes an oil obtained by the dry distillation of aniline blue. The author is disposed to regard the product as diphenylamine. With nitric acid, and apparently all oxidising agents, diphenylamine yields a magnificent blue colour. Some other reactions of this body are curions, and we shall return to them. in which one atom of hydrogen H is replaced by the group by M. Langier. The author sewed together the divided C2H2 A fact of great importance was mentioned in a memoir ends of a median nerve, and found that they perfectly united. Sensation and power of motion were re-established in the limb in the course of some days, and to a certain extent in a few hours. NOTICES OF BOOKS. A Companion to the British Pharmacopœia; comparing the Strength of the Various Preparations with those of the London, Edinburgh, and Dublin, United States, and other Foreign Pharmacopeias; with Practical Hints on Prescribing. By PETER SQUIRE, F.L.S., &c., &c. London: Churchill and Sons. 1864. MR. SQUIRE is already favourably known to the Medical and Pharmaceutical world as the author of two very useful compilations. The present work will greatly increase his reputation. Par excellence it is the work on the British Pharmacopoeia. (Same strength as Lond.; half that of Edin. and Dub.) Dose, to 1 oz. "TINCTURA.-Digitalis, dried and bruised, 1; proof spirit, 8; macerate forty-eight hours with 6 of spirit, agitating occasionally; pack in a percolater and let it drain, then pour on the remaining spirit; when it ceases to drop, press and wash the marc to make up 8. 66 (Same as Dub.; Lond. and Edin., 1 to 10; Fr. 1 to 5; Belg., 1 to 6; Pr., i to 7; Austr., 1 to 8.) "Dose-as a diuretic, 20 to 30 minims." The above extract requires a little explanation. It will be seen that Mr. Squire expresses some of the formulæ in parts. So long as these are taken as ounces no doubt will be felt, since the author gives at the top of each page the general direction "solids by weight, liquids by mea sure. But if pounds are thought of, it must be remembered that by a liquid pound the author means sixteen fluid ounces. Aiming also at great conciseness, the author will at times puzzle a simple-minded reader, as at page 14, where he describes Etheris nitrosi spiritus as "distilled from nitrite of soda." It would have been better. in such a case to have given the whole directions. There is, how ever, a note to this preparation which we give as a sample of the remarks which will be found scattered about the book. "This preparation will always be of uncertain strength, in consequence of the variable composition of the nitrite of soda made according to the Pharmacopoeia. This substance is a mixture of nitrate, nitrite, carbonate, and caustic soda, and will in no case fulfil the conditions laid down in the Pharmacopoeia test. The proportion of nitrite will vary from 5 to 25 per cent. (never more), and the strength of the spirit of nitrous ether will be influenced accordingly." There are also some remarks on the Liquor ferri perchloridi which we are tempted to extract :— "Liquor ferri perchloridi made by the process of the Pharmacopoeia has a sp. gr. 1395, is almost black, and contains both protochloride of iron and free nitric acid. When mixed with three times its volume of rectified spirit, as directed for making the tincture, a considerable deposit is soon produced. If the evaporation is pushed to 6 ounces instead of 10 as directed, complete oxidation takes place, but a large quantity of basic chloride is thrown down, because there is not sufficient hydrochloric acid to keep it in solution, and the nitric acid is not got rid of. This, by gradually acting upon the alcohol, producing ether, will cause the tincture to become turbid. "In order to have a successful result, the quantity of hydrochloric acid must be augmented to 13 ounces, and the solution should be evaporated to 5 ounces. The addition of 5 ounces of water will then bring up the bulk to io ounces, as required by the Pharmacopoeia, and the sp. gr. will be 1400. The tincture made with this solution will remain bright, and have the sp. gr. o'992." Mr. Squire was a member of the Pharmacopoeia Committee, and we must express our regret that he has had to make such remarks as the foregoing in his book. 2. Phosphoric chloride also attacks sulphides, and forms metallic sulpho-phosphides. 3. Sulphophosphide of mercury has a definite composition:-PS,,3(HgS). 4. Chlorosulphide of phosphorus can be obtained by the action of PC1, on SbS3. 5. Many chlorides may combine with PC1, to form welldefined compounds. 6. Among these is a compound of bichloride of platinuin with PCI, obtained by sublimation. 7. Phosphoric bromide, PBr5, dissociates easily. In the presence of carbonic acid it splits up completely into PBr3 and free bromine. 8 and 9. A bromoxide of phosphorus, PBrO2, and a bromosulphide of phosphorus, PBr2S2, exist. The author concludes his paper with a caution to experimenters on the disastrous effects of breathing the vapours of the chlorides of phosphorus and their derivatives. An interesting memoir by M. Barbier follows, "On the Application of the Phenomena of Capillarity to the Construction of Various Thermometers," which is much too long for us to transcribe, and which would hardly be intelligible without the accompanying plates. A translation of Mr. Graham's paper "On the Molecular Mobility of Gases" concludes the number, showing that its importance and value are thoroughly appreciated by our neighbours. It is the third translation into French we have noticed. NOTICES OF PATENTS. Communicated by Mr. VAUGHAN, PATENT AGENT, 15, Southampton Grants of Provisional Protection for Six Months. 1320. James Haswell Burke, London, "Improvements in lamps, vessels, tubes, and cocks, especially useful for preventing the transmission of flame or explosive action when using petroleum, camphine, or other inflammable or explosive substances."-Petition recorded May 27, 1864. 1335. Thomas Drew, the elder, Derby Villa, Tranmere Park, Birkenhead, "Improvements in the manufacture of paper, papier mache, and millboard." 1342. William Edward Newton, Chancery Lane, Middlesex, "Improvements in the treatment of the low or poor products obtained in the manufacture or refining of sugar.' A communication from Eugene Bartholomey, Rue St. Sebastien, Paris, France.-Petitions recorded May 30, 1864. 1346. George Davies, Serle Street, Lincoln's Inn, Middlesex, "Improvements in artificial teeth, and in moulds for forming the same." A communication from John Terrel and Joseph Stulb, Philadelphia, Pennsylvania, U.S. There is one useful feature in the work to which we shall call attention by another extract. The author, as often as necessary, after the officinal preparations of a medicine, gives a list of non-officinal remedies. Here is one :-"Tinctura chloroformi composita. — Chloroform, 4 oz.; rectified spirit, 4 oz.; treacle, 4 oz.; extract of liquorice, 2 oz.; muriate of morphia, 8 grains; oil of peppermint, 16 minims; syrup, 17 oz.; prussic acid-Petition recorded May 31, 1864. (2 per cent.), 2 oz." This, the author states, has been represented to him as the composition of chlorodyne, but we cannot suppose he believes the representation correct. There will be less than a quarter of a grain of muriate of morphia in an ounce of the above preparation, and Mr. Squire gives the maximum dose at 10 minims. We have no wish, however, to be hypercritical on a work which contains so much to be commended; and shall now only repeat our already expressed opinion that this is the best work which has yet appeared on the British Pharmacopoeia. Annales de Chimie et de Physique. May, 1864. THE greater part of this journal is filled with a paper by M. Baudrimont "On the Chlorides and Bromides of Phosphorus." The novelties in the paper are thus summed up 1. Phosphoric chloride (PC) attacks most elements, and especially the metals, sometimes forming double chlorides, more often forming a metallic chloride and phosphorous chloride (PC13). 1286.-Richard Archibald Brooman, Fleet Street, London, "Improvements in apparatus for increasing the illuminating power of gas, and for producing gas by the vaporisation of hydrocarbons and essences of petroleum."-A communication from Gustave Bouchery and Jules François le Batteux, Paris, France.-Petition recorded May 21, 1864. 1336.-James Paterson, Greenock, N.B., “Certain improvements in the cooling and preparation of charcoal to be used for refining sugar, and in the machinery, apparatus, or means employed therefor."-Petition recorded May 30, 1864. 1366.-Oscar Eugen Prieger, Bonn, Prussia, "The manufacture of ferromanganese and cupromanganese, and the combinations or alloys thereof with other metals." 1368.-William Cormack, Little Moorfields, London, "Improvements in the distillation or destructive distillation of all solid matters or semi-solid matters capable of yielding fluids, or gaseous hydrocarbons, or other products of any kind whatsoever, be they liquids, fluids, or solids, such as pit-coal, boghead, or other bituminous coal or shale, peat, wood, asphaltes, tallow, lard, fats, or other semi-solid matters, and in the treatment of the same." ΤΟ Notices of Patents-Correspondence. July 2, 1864. 1370.-William Henry Mellor, Liverpool, Lancashire, apparatus for taking up the emanations and the gases from "Improvements in self-acting, mashing, or saturating boilers." apparatus for the use of brewers, distillers, and others."- 360. John Henry Johnson, Lincoln's Inn Fields, MiddlePetitions recorded June 2, 1864. sex, "Improvements in the manufacture of superphos1386.-William Clark, Chancery Lane, Middlesex, "Im-phates to be employed in the making of bread and in other provements in electro-magnetic and magneto-electric apparatus, and their application as a stationary or locomotive driving power."-A communication from Jean Henry Cazal, Boulevart St. Martin, Paris. 1387.-Bondy Azulay, Rotherhithe, Surrey, "Improvements in treating petroleum and its products, and in the application of apparatus for that purpose."-Petitions recorded June 3, 1864. 1401.-James Napier, Glasgow, Lanarkshire, "Improvements in separating certain metals and metallic substances from ores and other matters." 1406.-Edward Loysel, Manor House, Clapham, Surrey, "Improved apparatus for obtaining extracts from tea, coffee, and other vegetable substances." 1408. William Clark, Chancery Lane, Middlesex, “Improvements in the preparation of phosphates of ammonia and ammoniaco-magnesian phosphates."-A communication from Emmanuel Adrien Lesieur, Boulevart St. Martin, Paris.-Petitions recorded June 6, 1864. 1412. Henri Adrien Bonneville, Rue du Mont Thabor, Paris, France, Improvements in telegraphic printing apparatus.”—A communication from Victor Delaye, Rue de la Paix, Paris, France. 1418. Arthur Thomas Weld, Gravesend, Kent, and John Folliott Powell, Albion Place, Hyde Park, Middlesex, "Improvements in the separation of animal substances from rags of mixed fabrics."-Petitions recorded June 7, 1864. 1425. Thomas Richards, Wincanton, Somersetshire, "Improvements in liquid manure and water carts.' 1426. Ferdinand Henry Warlich, Maze Hill, Greenwich, Kent, " Improvements in the manufacture of artificial block fuel and coke, and in apparatus employed therein." -Petitions recorded June 8, 1864. " 338. William Culley Stobart, Etherley, Durham, "Improvements in coke ovens."- Petition recorded February 9, 1864. 355. Thomas Vincent Lee, Macclesfield, Cheshire, "Improvements in the construction of kilns or retorts for coking, and for apparatus connected therewith for collecting the products of distillation through the agency of hydro-caloric or superheated steam, these appliances being applicable to making wood, charcoal, and collecting pyroligneous acid during the process." 357. Jean Marius Faget, Bordeaux, France, "Improved purposes in the arts."-A communication from Anthony Pollak, Washington, U.S.-Petitions recorded February 11, 1864. 432. Frederick John Arnold, Adam's Court, Old Broad Street, London, "Improvements in apparatus for producing and burning combustible gases for heating and lighting purposes."-A communication from Thomas Arnold, New York, U.S.-Petition recorded February 19, 1864. 472. Jean Francois Rivier, Boulevart de Strasbourg, Paris, France, "An improved system for filtering and purifying liquids with an endless spouting capillary filter." -Petition recorded February 25, 1864. 634. John Platt and William Richardson, Oldham, Lancashire," Improvements in machinery or apparatus for breaking up or pulverising clay for the manufacture of bricks or other such articles, or for breaking up or pulverising other material." 635. Raymond Fletcher, Siddall's Road, Derby, "A new compound used for varnishing paperhangings and other articles."-Petitions recorded March 12, 1864. 674. Richard Archibald Brooman, Fleet Street, London, "Improvements in treating vegetable textile matters, in separating filamentous matters therefrom, and the application of such matters to spinning, weaving, and dyeing." -A communication from E. M. F. Bonneau, A. Dumont, and N. J. C. Canoby, Paris, France.-Petition recorded March 16, 1864. CORRESPONDENCE. Continental Science. PARIS, June 28, 1864. As your readers, in common with all the other inhabitants of Great Britain, take the greatest possible interest in the weather, I cannot do better than begin my letter with that topic. For the last fortnight the temperature has been at fever heat, and the consumption of ices has been correspondingly high. On Sunday, however, to the delight of everybody, even of the holiday makers, the rain came down in torrents, and agreeably cooled the air. It is, perhaps, as well for you that the heat has moderated, for when the thermometer rises to such a pitch as it did last week, and stops there so long, there is an irresistible temptation to explore the woods round Vincennes (which, by the way, are almost denuded of their foliage by caterpillars) in search of botanical specimens, which somehow always die before one gets home, or ransack the quarries of St. Denis for fossils, which are always left behind, instead of attending hot lectures or writing letters with the perspiration bedewing the paper. The subject of the sun leads one directly to photography. At the last meeting of the Photographic Society the Abbé Laborde read a paper on the "Reproduction of Kaleidoscopic Figures." I have always imagined that the great beauty of these figures resided in their colour, and to what end, therefore, should they be photographed? M. Laborde says these photographs would be useful to designers, but I fancy no decorative artist would be worth much who would seek the aid of the kaleidoscope for his patterns. M. Van Monckhoven read a paper on a new enlarging camera, which he has just perfected. The specimens exhibited are certainly the best enlargements yet seen, and by using a large lens of 19 inches in diameter for collecting the rays, an excellent positive may be taken on common albumenised paper in from twelve to fifteen minutes. The Abbé Moigno, the esteemed editor of Les Mondes, has commenced giving monthly lectures to the subscribers to that journal, detailing the progress made in the different |