by the hydrogen corresponds to a line of shadow or darkness produced by the olefiant gas, the one having more refracting power than the air, and the other being less refracting than the air. Those ar points that I trust you will follow out in your own thoughts afterwards. We cannot well do it now. I want now to prove to you that what I have said with regard to lenses is a matter of ocular demonstration, and I have here a large converging lens, called a plano convex lense; one side is bulged out and the other is perfectly flat. If we cause the rays of light to fall upon it, they are converged or squeezed together. I will try and show you this convergence of the rays from the electric light by allowing them to pass through this large lens. Now these beams are not parallel, but that they issue from a point like our coal points yonder; I will call that the point a; there would be an image formed of it at the point which I call a'. Supposing I take another point here which I call b, and allow a conical beam of light to tall from it on the lens. On quitting the lens it will be refracted, converged, and brought to a point at b', and there we should have an image of the point b. Supposing there were a man at a b, and that mark a represented his feet and 6 his head, and the intermediate space the body. what would take place here with regard to the image? You see this point b—the head-would be downwards in the image, and the feet a up, so that the image produced by this double convex lens would be that of the object inverted. And thus if I take any object-supposing a candle-and throw upon it a beam of light from the lamp, and place it behind the lens, you have the candle thrown on the screen inverted, just as I said the image would be inverted. Now, I wish to show you the image of these coal points with which we have been hitherto operating, and for that purpose I will interpose a lens in front of this lamp, and I will throw my beam through that lens, and we shall see immediately whether we cannot by means of the lens make an image of the coal points upon the screen. Here we have the image of the coal points with which we have been operating, but you see they are rather dim; they are surrounded by a blotch of light which rather dims their definition. Why does that blotch of light exist? Can we bring out those coal points in strict and beautiful definition upon the screen? We can do it in this way. The reason that you see that blurred light there is this. I have the convex lens before the lamp and behind it I have a source of very intense light those who are looking in a certain direction,-and I am Burry to say this room is not so foggy as I should like it to be will see a fine cone of rays issuing from that lamp and after passing through the lens coming to a point; and if I cause the lens to turn round, the cone will travel round. There is the fine convergent cone produced by this plano-convex lens. You see we get this splendid cone produced by the converging power of the lens, and those who are sharp-sighted enough will observe even in this atmosphere the light diverging from the coal points. Beyond the lens, outside the cone, there is a space of darkness, and the rays are actually squeezed away from the space of darkness so as to form this cone; and if I interpose a screen in the path of the beam. I get a bright disc of light, and at the focus I have actually a blurred image of these coal points from which the light emanates. The blurring will be explained after wards, but here you see an image of the coal points produced by the collection of all the rays by the lens. This lens, like a skilful architect, has built up these particles of light, like so many bricks, into an edifice of exactly the same kind as tha: from which they issue. I want now to show you some of the images produced by lenses of this kind. Supposing I have a convex lens, and I allow the beam of light to fall upon it obliquely. On quitting the lens the light will be con verged to a focus and come to a point, Now, suppose t When the rays of light fall from that point (a) on to the edge of that lens (b c). they are bent, and pass on in that direction (b d, e d). Now, let me take a portion of the centre of the lens, and let the beam fall upon the part e ƒ. When it enters it will be refracted, and when it quits the lens it will also be refracted. but it will not be refracted so much as the rays that have entered the edge are refracted, so that the focus of the edge and the focus of the certre rays are not the same. The focus of the centre rays (at g) not being the same, you get a quantity of light round it which blurs its definition, but if you cut off the circumferential rays, and use merely the rays near the centre, you get a beautiful a d clear image of the coal-points. I will endeavour to do that in this way, You see I have a piece of metal with a hole in it of not more than about an inch and a-quarter in diameter, and if I interpose this so as to allow the rays from the middle portion of the lens only to pass through, then we shall obtain a clearer image of the coal-points than we have had hitherto. Now, I ask you to observe what a beautiful image we have obtained of these coal-points, without any blur or indistir ctness. This image is produced by these central rays, and here the inversion I have already spoken of takes place. This point that you see move up and down is really the topmost point of the two, though it is inverted on the screen, and when it appears to be moving up, as it is now, it is really going down. Notice what takes place when we bring these points near together. See how the one appears to devour the other,-to eat it up,-the one consuming the other. You find the substance of the one is becoming heaped up on the other, and so in one we have a point, and in the other a crater, or hollow form. Allow me now, in conclusion, to show that we can make with these lenses the same experiments that we made with a concave mirror. I have here a double convex lens, and we will place our lamp so as to illuminate these medals, and I think I can show you some beautiful images upon the screen by means of the lens-as beautiful, at least, as those that we obtained by means of the concave mirror. Now, for that purpose we must have our lamp pointed to you, in order to illuminate the objects; but, boys, do not fear a gush of light. I will take first of all this copper medal, turn it upside down, place the lens in front of it, and try to throw its reflection upon the screen. Having shown you the copper medal, here you have an inverted image of the silver medal, brighter but still not more beautiful than in the other case. In our next Lecture we shall deal with that most wonderful of all optical instruments-that most wonderful collection of lenses in Nature-the human eye; and I trust we shall not part before we have made ourselves perfectly well acquainted with its construction. NOTICES OF PATENTS. 39 iron. Very light and durable horse-shoes are said to be thus obtained. 853. Preparing, Applying, and Adapting certain Vegetable Pr ductions, to further the purposes of Manufacture. T. G. GHISLIN, Hatton Garden, London. Date April 6, 1861. (Not proceeded with.) THIS invention relates to the manipulating and manufacturing, by chemical and other processes, certain vegetable productions found in, and indigenous to, South Africa. The first article, a marine plant or fungus, known tɔ botanists under the name of Eiklonia buccinalis, the inventor applies to veneering and inlaying purposes, or, after being stamped and embossed, as a substitute for leather, shagreen, etc., or, instead of horn, for knifehandles. The second article, known as the Juncus trista, is suitable for basket-work, instead of reeds or cane. Other vegetable productions, Juncus serratus (an aquatic), and certain members of the armyllideæ, are applied by the inventor, in the form of fibres (alone, or mixed with other materials), for the purpose of coating submarine cables, and for insulating electric wires in general. 877. Improvements in the Manufacture of Artificial Stone and Cement, or Plaster, and in Treating Timber, for the purpose of Preserving the same. F. RANSOME, Ipswich. Dated April 9, 1861. 796. Artificial Substances to be used as a Covering for Stone, Bricks, Wood, &c. J. BRIGGS, Bridge Street, Black-calcium, or other soluble salt of an alkaline earth, or with friars, London. Dated March 30, 1861. (Not proceeded with.) FOR these improvements the inventor uses coal-tar-pitch, lime, and gravel, the latter of such size as will pass through the meshes of a one inch seive. The relative proportions in which these ingredients are mixed may be varied according to the nature of the application : for general purposes he takes 10 parts of pitch, 1 of lime, and 50 parts of gravel. The pitch is first melted in an open cauldron, the lime added, and lastly the gravel, which must previously have been heated to about the same temperature as the melted pitch. The materials are well incorpo rated and pressed into molds to form flags or blocks. In proposing to use the same as an upper coating for bricks or stone, the inventor recommends the employment of sharp river sand or grit in the place of gravel. Mixtures of coal-tar-pitch and gravel or broken stone have frequently been employed for the purposes herein specified, and are commonly laid down as cheap substitutes for asphalte. 797. A New Method of Colouring, as a Substitute for Saffron, in the Manufacture of Cheese, &c. G. RUSSE, Geroa. Dated April 1, 1861. (Not proceeded with.) THIS invention consists in the substitution of curcuma root (turmeric) for saffron in all the various purposes to which the latter is usually applied, especially in the tinting of cheese, pastes, vermicelli, etc. The employment of turmeric for the colouring of pastry and articles of confectionery was pretty generally understood and practised in England long previously to the date of this specification, April 1. 842. Shoes for Horses. W. EDWARDS, Wolverhampton: Dated April 5, 1861. (Not proceeded with.) IN making the aforesaid shoes the inventor employs a compound metal obtained by rolling and welding together iron and steel, so that the wearing parts or surfaces shall consist of hard steel, and the remainder of For the purpose of manufacturing artificial stone, the patentee mixes powdered chalk with the solution of an alkaline silicate, and moulds the compound into blocks or shapes. Afterwards, when the blocks are sufficiently dry, he washes over the surface with a solution of chloride of a solution of chloride of aluminium or iron, for the purpose of converting the alkaline silicate into an insoluble silicate of lime, alumina, or iron. In the treatment of wood for the purpose of preserving the same, he forces into its pores a solution of silicate of soda, and afterwards applies the chloride of calcium, or other earthy salt, as before. The material produced, according to the terms of this specification, was submitted by Mr. Ransome to the Par liamentary Committee on the Decay of Stone, in May last, and the character of the silicated blocks has already been fully described in our notices of the Committee's Report. 892. Drying and Preparing Grain, Seeds, or Berries for Food. T. DON, Poultry. London; T. SMITH, Tenter Lane, Leeds; and L. HORSFIELD, Bank Foundry, Leeds. Dated April 11, 1861. THE patentees, in carrying out these improvements, avail themselves of the use of heated air, steam, super-heated or otherwise, which they cause to pass through suitable pipes, arranged in a horizontal position, and enclosed within an upright case. The grain, seeds or berries to be desiccated are allowed to descend among the heating surfaces, and the moisture so evaporated drawn off by means of an exhausting fan, or other equivalent mechanical contrivance. Grants of Provisional Protection for Six Months. 2495. William Clark, Chancery Lane, London, "An improved gas regulator and purifier."-A communication from Jean Baptiste François Maliquet-Allegret and Lucien Victor Teste, Rue Ferrandière, Lyons, France.recorded October 5, 1861. 2976. John Henry Johnson, Line don, "A new or improved to womb in cases of prolapsu from Doctor Otto Langgaar November 26, 1861. 2999. Charles Stevens, C On the Specific Gravity of Liquid and Solid Substances. To the Editor of the CHEMICAL NEWS. SIR,-In the CHEMICAL NEWs of December 28, 1861, is an article by O. Richter, Ph.D., on the Specific Gravity of Substances in the Liquid and Solid State, which brings forward a want that I for one have long felt, viz., full and trustworthy tables of specific gravities; and I am persuaded that there are many who will be truly thankful if the CHEMICAL NEWS or Dr. Richter will supply this desideratum. Mr. Richter makes some valuable remarks upon the philosophy of the subject, which are certainly well worthy of consideration. He reminds us also of the deeply interesting experiments of Playfair, now many years ago, which it is certainly the unanimous desire of those who devote themselves to the philosophy of Chemistry, that the gifted Professor of Chemistry in the University of Edinburgh would resume. These experiments, Dr. Richter saya," appear to conceal within them a profound philosophical truth, viz., that the eighth part of the volume of ice is really the standard whereby the volume equivalents of the various chemical elements will one day be correctly measured and calculated." Generalising this statement, I am fully persuaded, after much inquiry, that it will be found to be perfectly true. At all events the theory of specific gravities having been triumphantly established in reference to one class of substances (aëriforms), that theory surely ought not to be abandoned in the further pursuit of the subject, until it has been shown to be inadequate. It has been established that the specific gravities of all aëriforms may be derived from their atomic weights, on the theory that their atomic or molecular volumes are either the same or in simple ratio with those of the ambient medium (N= 14, O= 16), and therefore with one another, to maintain which law and harmony we know that they are capable of wonderful compression or diminution of some kind. Thus the aëriform molecules by which the vegetable kingdom is rendered fragrant, whose formula is never simpler than C20H16 have each a volume no larger than that of a particle of atmospherical nitrogen and oxygen taken as one, and so in other cases, according to a theory which is well entitled to all regard. Now, why not attempt to carry out this theory in reference to dense molecules; the molecules of bodies in the liquid and solid state? Of course we cannot look to the atmosphere for an unit volume. But we are not without a great cosmical element, and as we might say an ambient medium, here as well as in reference to aëriforms. The sea viewed as resting in its own basin, and in its allpervading arms and products, lakes, rivers, springs, and percolating waters, and with the abundant evidence that there is of its prevalence during all geological epochs, suggests itself in reference to dense bodies as holding the same relation to their molecules that the atmosphere does in reference to aëriform molecules. And hence the question-Ought we not, in extending the theory of specific gravities when we arrive at dense substances, to view them in reference to an unit volume of water, as we view aëriforms in reference to an unit volume of air? May we not legitimately conjecture and enquire, unless the contrary appear, that just as there seems to be a law in virtue of which the particles of bodies, when forming into aëriform molecules, shall conform in volume or be in harmony as to volume with that of the particles of the ambient atmosphere, so the same law may require with regard to dense molecules, or the molecules of liquid and solid bodies, that the elementary particles which go to constitute them shali group together in such numbers as shall give molecules conformable in volume as nearly as possible to the all-pervading dense element of the terraqueous globe, viz., a particle of water or of ice? Or more generally, are we not to expect, in the absence of evidence to the contrary and of adequate enquiry, that just as we find that Nature aims at a standard volume with respect to aëriform molecules of which an element of the atmosphere may be taken as the type, so we may enquire with advantage, whether she does not the same with respect to liquid and solid molecules of which a molecule of water or of ice may be taken as the type? I have pursued the enquiry on this hypothesis to a considerable extent, and hence obtained results which are equally unexpected and beautiful, and which bring the inorganic world, as it is commonly called, into exquisite harmony with the organic, which latter is now best known as to the molecular constitution of its elements. These results I shall be very happy to communicate to you, duly Macadamised for a weekly periodical, should your insertion of this lead me to infer that they would be acceptable. I am, &c. T. M. S. Spectrum Analysis. To the Editor of the CHEMICAL NEWS. SIR,As your valuable Journal is generally recognised as containing the most complete account of the progress of "Spectrum Analysis," I venture to trouble you with the following. One of the most beautiful and instructive experiments that can be performed with the "Spectroscope" is the exhibition of the two spectra in the field of view at the same time, for the purpose of comparing the various lines with each other. This is generally done by refraction, while I have advantageously employed reflection by a prism. The following simple and inexpensive method will, however, be found very efficient: Take a piece of white card or polished tin about four inches square and fix it on a support in a vertical position in front of the instrument, first cutting it in such a manner that the edge may be in close contact with the adjusting elit and exactly bisecting it. If the two burners be now placed one on each side of the tin or card, and as near to it as possible, the two spectra will be at once visible. As I know many of your readers have a "Spectroscope," the hint may prove serviceable to them, but this plan cannot of course be adopted with any other form of Spectrum Apparatus, as the slit in the whole of them is vertical, which precludes the possibility of employing any such arrangement. CHEMICAL NEWS, Jan. 18, 1862. Correspondence-Chemical Notices. The copper spectrum being one of great beauty, may be easily obtained in a very fine manner by dipping a piece of copper wire about a quarter of an inch in diameter in hydrochloric acid and then bringing it to a dull red heat in a Bunsen's burner.-I am, &c. JOHN BROWNING. 111, Minories, E. C., January 13. Preparation of Pure Hydrochloric Acid. To the Editor of the CanмICAL NEWS. SID, It may be useful to some of your readers to know that pure hydrochloric acid for toxicological purposes may be prepared from the distillation of chloride of potassium or sodium and oxalic acid in equivalent proportions. I have found the acid so produced to be pure. The residue in the retort dissolves in water, furnishing the salt. NaO2 (C, O,) + z Aq Should you think this worth notice, by placing it in your Journal you will oblige me.-I am, &c. THOMAS BLOXAM, F.C.S., Lecturer on Chemistry, Grosvenor-place School of Medicine. 28, Duke Street, Grosvenor Square, W. Chemical Nomenclature. To the Editor of the CHEMICAL NEWS. SIR,-I have already given a list of numerals sufficiently extensive to provide names for the great bulk of organic bodies, but they may also be formed even for substances containing several hundred equivalents of carbon, hydrogen, &c. For this purpose the names are constructed in two parts, separated by a hyphen, the letters and syllables composing the first part being understood as representing ten times the value of those composing the second part. Thus, b, d, f, &c., if commencing the second part of a name, signify C, C, and C, respectively, whereas in the first part they severally represent C10, C20, and C30 The same numerals that are used for oxygen may also be employed to denote the amount of nitrogen when present in large quantity, the second syllable of any name giving the oxygen and the third syllable the nitrogen. 160 For example, let us take one of the formula which have been assigned to the albumen of blood-viz., C108 H169 034 N27 S, all of which may be remembered by the name pedfa-mangates albumen, or pedfa-mangatesone. In the first part of this name p signifies Coo, ed Hi and fa O 30. and in the second part m is C, an H,, ga 04, te N2, and 8 S, making together C108 H169 034 N27 S. It may be said that this name does not indicate the amount of phosphates in albumen, but neither does the formula; and surely it cannot be expected that a name shall be both short and at the same time actually give more information than the formula from which it is derived. We thus see that with a list of numerals only half as extensive as that contained in my previous paper, it is possible to construct a name expressing the composition assigned to albumen itself, and one which, though inferior in point of sound, is not longer than those usually given to the simplest of inorganic substances. Chemical Notices from Foreign Sources. I. MINERAL CHEMISTRY. 4I Nitrogen in Meteoric Iron.-The constant presence of nitrogen in ordinary iron led M. Boussingault to look for it in meteoric iron. The specimen he examined (Annales de Chimie et de Physique, T. lxiii., p. 336), fell at Lénarto, in Hungary, and besides the iron and nitrogen, contained the mixture of metals usually found in meteoric the results of which gave 0'000102 of a gramme of nitrogen stones. M. Boussingault made three very careful analyses, in each gramme of the aërolite. NEWS, Vol. ii., p. 143), Von Kobell ar nounced the discovery Dianium or Niobium.-Two years ago (CHEMICAL of a new metal to which he gave the name Dianium. He found the metal, or rather an acid oxide of it, in minerals up to that time supposed to be mainly composed of hyponiobic acid. MM. Deville and Damour have examined some of the same minerals (Comptes- Rendus, T. liii. p. 1044) and have come to the conclusion that what Von Kobell called dianic acid is only a modification of one of the acids of niobium. This opinion is shared by Hermann. Von Kobell replies, but we fear he must give up dianium. Simultaneous Action of Air and Ammonia on Copper.-Peligot is well known by his earlier experiments on the ammoniacal salts of copper. Anticipated in some of his results by Schoenbein, he has continued his experiments, and now (Annales de Chimie et de Physique, T. lxiii., p. 343), gives the latest conclusions he has arrived at. He distributes finely-divided copper (obtained by reducing a salt by iron or zinc) about the sides of a large flask, into which he poured a small quantity of very strong ammonia. The vessel soon became warm, and white vapours were seen, which Peligot found to be composed of nitrite of ammonia. On repeating this experiment several times, taking care to refill the flask with air, a blue liquid is obtained. (It is unnecessary to add more copper, as very little is acted on in one experiment; but the points of contact must be changed.) This blue liquid the author found to contain a double nitrite of copper and ammonia. Crystallized and dried in the air, it had the formula NO3, CuO NH,O, HO. When boiled, this salt became green, lost its ammonia and water, and there remained anhydrous nitrite of copper, NO,CuO. The double salt, wrapped in paper, placed on an anvil and struck with a hammer, detonated. When the solution of the double salt is added to water, a turquoise blue precipitate of hydrated oxide of copper is obtained, which enjoys the remarkable property of preserving its colour in the air. It slowly absorbs carbonic acid, and becomes carbonate of copper without changing colour. M. Peligot thinks the same oxide may be cheaply prepared and become an important article in industrial art. The ammoniacal solution of the double salt above mentioned, is said, by the author, to be the best agent for dissolving cellulose, for that substance is precipitated again without alteration on the addition of an acid. Preparation of Chlorosulphide of Phosphorus. Perhaps when the formulæ of these highly complex-M. Baudrimont observed that chlorosulphide of phosbodies have been thoroughly investigated, they may be resolved into something simpler, in which case the corresponding names will be improved in sound, and rendered more in accordance with those now in use. I will only add that this system of nomenclature may be applied to other sciences, and that the same names which represent the quantities of carbon, hydrogen, &c., in organic substances may also serve to denote the species, genera, &c., to which particular plants or animals belong. With many apologies for again trespassing on your valuable space, I am, &c. JOHN A. R. NEWLANDS, F.C.S. 1 Gregory's Handbook, fourth edition, p. 496, using Gerhardt's equivalents. phorus was formed whenever the pentachloride came in contact with sulphur, whether free or in the state of sulphide; and after many attempts he succeeded in obtaining it easily and abundantly by the reaction of PC1, on SbS3, conducted in the following way (Comptes Rendus, T. liii., p. 468):-In a very large flask he placed 15 grammes of well-dried phosphorus, and having removed the atmospheric air by a current of carbonic acid, he passed dry chlorine until the whole of the phosphorus was converted into perchloride. He then removed the flask into a large yard (to avoid the disagreeable effects of the chlorosulphide on the eyes and air passages) opened it, and dropped in by degrees 115 grammes of sulphide of antimony. The first portions took some time to act, but presently the flask heated, and white vapours were disengaged, and the portion of the sulphide was then added which acted quicker; and so on until the whole of the sulphide had been used. It is necessary to shake the flask well often to break the crystalline crusts of the pentachloride which form on the sides of the flask and then fall on the sulphide. The neck of the flask should be surrounded with a wet cloth to absorb the vapours of PC13S, which tend to escape. As soon as a slight excess of sulphide of antimony is seen, the flask is connected, and the chlorosulphide carefully distilled between 125° and 135°. Any chlorides of antimony or arsenic which may distil can be removed by shaking the chlorosulphide with a dilute solution of sulphide of sodium, the two liquids being separated by means of a separating funnel. The chlorosulphide is then treated with chloride of calcium and rectified. All these processes must be conducted in well-closed vessels, in consequence of the irritating effects of the chlorosulphide, which should afterwards be kept in a well-stoppered bottle under a bell glass with some quicklime. The author thinks that this body will be a powerful agent in modifying (probably sulphurizing) many organic bodies, and ɛo give rise to a great number of new products. II. ORGANIC CHEMISTRY. Compound of Nicotine with Chlorobenzoyl.— Will obtained (Annal. der Chem, und Pharm. Bd. cxiii. 8. 206), by adding a solution of nicotine in anhydrous ether to chlorobenzoyl, a precipitate of a glutinous liquid which, on standing for some hours under the layer of ether, deposited white prismatic crystals. Removed from the ether, and left in moist air, these crystals soon deliquesced and formed a yellow syrupy liquid. They had the com position CH2NO,Cl, and may be regarded either as chloride of benzoyl nicotine COHN, CIH, C14H3O2 or as chloro-benzoyl-nicotyl-ammonium, C10H, Aribin.—Martius has discovered a new vegetable organic base, to which the name Aribin has been given by Wöhler (Chem. Centralblatt, December 4, 1861). It has the composition C6H20N4. and is the first example of a non-oxygenated organic, base of a stable crystalline form, the other non-oxygenated bases (e.g. Coneine nicotine) being fluid. The aribin was obtained from a tree growing in Brazil and known as the Arariba rubra. The author gives a long account of its preparation, reaction, and compound, to which we may return when space permits. and then in distilled water; and after all this, the cotton retained enough starch to be coloured blue with iodine. Coal Tar to Prevent the Potato Disease.— M. Lemaire (Comptes Rendus, T. liii. p. 1074) mixed two per cent. of coal tar with earth, scattered the mixture over his ground, dug it in eight inches deep, and then planted his potatoes. None of those protected by tar showed any sign of the disease, while more than half of some planted at a short distance on the same day, and loft unprotected, were found to be diseased. Use of Baryta Salts in Dyeing and Printing.— Frightened at the prospect of manufacturers being some day hard up for potash, M. Kuhlmann proposes (ComptesRendus, T. liii. p. 1047,) to economise its use immediately by substituting baryta salts for the corresponding potash salts employed in dyeing and printing, e.g., the tartrate, chromate, and ferrocyanide. So far he seems to have tried only the tartrate of baryta, which appears to replace tartrate of potash successfully; but M. Kuhlmann is always a little mysterious. MISCELLANEOUS. Wood for Shipbuilding.-Professor Crace Calvert is now making an investigation for the Admiralty of different kinds of wood used in shipbuilding. It appears that the Professor is at no loss to explain why so many of the fleet of recently built gunboats became rotton and others escaped untouched. He finds the goodness of teak to consist in the fact that it is highly charged with caoutchouc; and that, if the tannin be soaked out of a block of oak, it may then be interpenetrated by a solution of caoutchouc, and thereby rendered as lasting as teak. A few years ago an enterprising individual spent 30,000l., in trying to introduce a new wood for shipbuilding purposes from South America, where it is known by the name of Santa Maria; but the dockyard authorities could not be persuaded to take it into use, and the imports were entirely neglected. professor; and he finds it to be sound and resinous, and This is one of the specimens investigated by the Manchester but little inferior to teak. Of the durability of teak there can be no question. ANSWERS TO CORRESPONDENTS. and Advertisements and Business Communications to the PUBLISHER at All Editorial Communications are to be addressed to the EDITOR: the Office, 1, Wine Office Court, Fleet Street, London, E.C. Leucic Acid and its Salts.-P. Waage has a paper on the above (Annalen der Chem. und Pharm. Bd. cxviii., 8. 295), which, however, does not add much to the information we gain from Dr. Thudichum's paper just published in the Quarterly Journal of the Chemical Society, Vol. xvi., p. 307. When heated to 100° C., says Waage, leucic acid volatilizes. The sides of a watch glass heated on a water bath becomes covered with a net work of crystals of the sublimed acid. These crystals easily dissolve in water, always leaving some flocculi which are probably the anhy-4, 1862, and will be complete in 26 numbers. dride of leucic acid. The syrupy mass left on the watchglass only dissolves in water after long boiling, but is easily soluble in alcohol and ether. This mass Waage thinks is anhydrous leucic acid: a direct experiment showed that the acid lost water when heated. For a further account of the acid and its salts, we recommend our readers to go to Dr. Thudichum's paper. adopt the views of the writers. Our intention to give both sides of a In publishing letters from our Correspondents we do not thereby question will frequently oblige us to publish opinions with which we do not agree. Vol. IV. of the CHEMICAL NEWS, containing a copious Index, is now ready, price 12s., by post, 12s. 8d., handsomely bound in cloth, goldlettered. The cases for binding may be obtained at our Office, price 18. 6d. Subscribers may have their copies bound for 28. if sent to our Office, or, if accompanied by a cloth case, for 6d. A few copies of Vols. I. II. and III. can still be had. Vol. V. commenced on January III. TECHNICAL CHEMISTRY. Resistance of Starch on Cotton Tissue to Solvents. -Chevreul (Comptes Rendus, T. liii. p. 984) boiled a cotton fabric impregnated with starch in distilled water for two hours, then soaked it in water and hydrochloric acid for eighteen hours, afterwards washed it with common water known weight (1 gramme) of the indigo with 8 or 10 parts of oil of |