Cantor Lectures. 8 38 2 2 100 and which has been erroneously called gelatine, is insoluble in water, weak acids, and alkalies, whilst gelatine presents properties directly reverse. But what has led to this popular error is that osséine, when boiled in water, becomes converted into the isomeric substance commonly called gelatine. As I shall have to dwell on this substance at some length in my next two lectures, I will not detain you now further than to state that osséine is obtained from bones by placing them in weak hydrochloric acid, which dissolves the phosphate of lime and other mineral salts, washing the animal matter (osséine) until all acid is removed, drying it, and treating it with ether to remove fatty matters. I cannot leave this subject without remarking on the extraordinary stability of this animal substance, for it has been found in the bones of man and animal after many centuries, and even in small quantities in fossil bones. The fatty matter of bones is made useful in the manufacture of soap, railway grease, and in other purposes; it is obtained by taking fresh bones (as bones which have been kept a long time will not yield their grease easily) and placing the spongy parts, or ends of the bones (where most of the fatty matter exists) in large boilers filled with water, which is then carried to the boil, when a part of the osséine is converted into gelatine, and the fatty matter liberated, which rises to the surface, and is easily removed. The bones thus treated are called boiled bones, and receive many important applications, to which your attention will be called in a few minutes. Benzine and bisulphuret of carbon have been used as substitutes for water in the above operation, but the advantages do not seem to have been sufficient to lead to their general adop tion. Mineral Matter of Bones.-These, as the foregoing tables show, are chiefly represented by phosphate and carbonate of lime. The immortal Berzelius was the first to establish the fact that phosphate of lime was the only substance possessing the properties necessary for the formation of bone, owing to the extremely simple chemical reactions which cause the soluble phosphates to become insoluble. Let us trace shortly the sources from whence we derive the large proportion of phosphate of lime which exists in our frames. Several of our most eminent chemists have proved the existence of phosphorus in sedimentary and igneous rocks, and the important part played by phosphorus in nature cannot be better conveyed to your minds than by this extract from Dr. Hofmann's learned and valuable Report on the Chemical Products in the Exhibition of 1862:-"Large masses of phosphorus are, in the course of geological revolutions, extending over vast periods of time, restored from the organic reigns of nature to the mineral kingdom by the slow process of fossilisation; whereby vegetal tissues are gradually transformed into peat, lignite, and coal; and animal tissues are petrified into coprolites, which in course of time yield crystalline apatite. After lying locked up and motionless in these forms for indefinite periods, phosphorus, by further geological movements becomes again exposed to the action of its natural solvents, water and carbonic acid, and is thus restored to active service in the organisms of plants and CHEMICAL NEWS, July 9, 1864. lower animals, through which it passes, to complete the mighty cycle of its movements into the blood and tissues of the human frame. While circulating thus, age after age, through the three kingdoms of nature, phosphorns is never for a moment free. It is throughout retained in combination with oxygen, and with the earthy or alkaline metals for which its attraction is intense." After these eminently philosophical views by Dr. Hofmann, I will proceed to call your attention to the application of bones to agriculture. Bones are generally used for manuring in one of these three forms,-Ist. As ground green bones ; 2nd. As ground boiled bones-(that is, bones nearly deprived of their osséine by boiling under pressure, as I shall describe in my next lecture); 3rd. Superphosphate of lime. Green or raw bones have been used on grass land for a long period, but their action is exceedingly slow and progressive, owing to the resistance of the organic matter to decomposition and the consequently slow solubility of the phosphate of lime in carbonic acid dissolved in water. What substantiates this view is that boiled bones are far more active than the above. It is found that 30 to 35 cwts. per acre of these will increase the crops on pasture land from 10 to 20 per cent. in the second year of their application. But the great advantage which agriculture has derived from the application of bones as a manure has arisen from their transformation into superphosphate of lime, especially applicable to root and cereal crops. To Baron Liebig is due the honour of having first called the attention of farmers (in 1840) to the importance of transforming the insoluble phosphate of lime of bones into the soluble superphosphate, rendering it susceptible of imme.. diate absorption by the roots of plants, and of becoming at once available for their growth. These suggestions of Liebig were rapidly carried out on a practical scale by Messrs. Muspratt, of Lancashire, and J. B. Lawes, of Middlesex; and in consequence of the valuable results obtained by them, the manufacture of artificial manures has gradually grown into an important branch of manufacture in this country. The manufacture of superphosphate of lime is so simple that any farmer possessing a knowledge of the mere rudiments of chemistry can make it for himself, by which he will not only effect great economy, but also secure genuineness of product. All he requires is a wooden vessel lined with lead, into which can be placed 1000 lbs. of ground boiled bones, 1000 lbs. of water, and 500 lbs. of sulphuric acid sp. gr. 1.845 (or concentrated vitriol), mixing the whole, and stirring well for about twelve hours. After two or three days a dry mass remains, which only requires to be taken out and placed on the land by means of the drill, or to be mixed with water and sprinkled on the land. When very large quantities of this manure are required, the plan devised by Mr. Lawes appears to me the best suited. It consists in introducing into the upper end of a slightly-inclined revolving cylinder a quantity of finely-ground boiled bones, together with a known proportion of sulphuric acid of sp. gr. 1.68. As the materials slowly descend by the revolution of the cylinder they become thoroughly mixed, and leave it in the form of a thick pasty mass, which is conducted into a large cistern capable of containing 100 tons, or a day's work. This is allowed to remain for twelve hours, when it is removed, and is ready for use. Most manufacturers find it necessary to add to the phosphate of lime of bones other sources of phosphates, such as coprolites, or the fossil dung of antediluvian animals, which have been found in large quantities in Suffolk, Cambridgeshire, and elsewhere, and contain from 36 to 62 per cent. of phosphate of lime, and from 7 to 38 per cent. of organic matter. Others employ a mineral substance called apatite, containing about 92 per cent. of phosphate of lime, and found also in large quantities in Spain, Norway, France, &c. Others, again, employ guanos rich in phosphate of lime, such as those of Kooria Mooria Islands With nitrogenated compounds. Without nitrogenated compounds. 8.15 20.08 7.25 19.17 5071 3.00 tions, such as those of tartaric and citric acids, in chemical works. He also prepared what he called coal-tar charcoal by melting one pound of pitch in a cast-iron pot, adding to it two pounds of coal-tar, and mixing intimately into it seven pounds of hydrate of lime, then carrying the whole to a high temperature, allowing it to cool, and removing the lime by washing the mass with hydrochloric acid and then with water, when carbon in a high state of division The following series of experiments by Dr. Stenhouse perwas obtained, possessing powerful decolorating properties. fectly illustrate the chemico-physical action of animal black as a decolorating agent. He boiled a certain amount of char and his two charcoals with a solution of logwood, then treated each black separately with ammonia, when the following results were obtained :-Aluminised charcoal-tar charcoal large quantities. But it would be wrong coal yielded no colour; bone-black but a slight amount; in me to leave you under the impression that animal black can only remove colours from solutions. Purified animal black-that is to say, animal black deprived of its mineral matters by the action of muriatic acid and subsequent washing-has the power of removing certain bitters from their solutions. Thus Dr. Hofmann and Professor Redwood applied this property with great skill some years ago to the detection of strychnine in beer. Again, Thos. Graham, Esq., Master of the Mint, published a most interesting series of researches, in which he established the fact that purified animal black had the power to remove a great number of saline matters from their solutions, such as the salts of lime, lead, copper, &c. Earths and alkaline silicates Earth. Bone-black or Char.-In 1800 Löwitz made the interesting observation that wood charcoal possessed the remarkable property of removing colouring matters from their solutions. In 1811 Figuier also observed that animal black had far greater decolorating power than wood charcoal, and bone-black has consequently become one of the Revivification of Bone Black.-After a certain quantity principal agents in sugar-refining, and has been the means, of syrup sugar has percolated through the cylinders conmore than any other substance, of producing good and taining bone-black, the interstices become so clogged with cheap white sugars. To give you an idea of the extent impurities that it loses its power of decolorating the syrup. to which bone-black is used at the present day for de- Sugar refiners are therefore in the habit of restoring the colorating purposes in the refining of sugar, I may state power of their bone-black, generally speaking, by subthat in Paris alone it is estimated that about 11,000,000 mitting it to a process of calcination, which volatilises or kilogrammes of bones are used annually for that purpose. destroys the organic matter fixed by the char. It has been The preparation of bone-black is simple in principle. It proved by experience that char may undergo this operation consists in placing in cast-iron pots about 50 lbs. of broken about twenty times before its pores become so clogged with boiled bones, that is, bones which have been deprived of dirt as to render it useless. [Here the lecturer described, their fat-of most of their osséine, and piling these pots with the aid of drawings, several of the various apparatus in a furnace, where they are submitted to a gradually used in sugar refineries for the above process, alluding rising temperature during twenty-four hours, such as will particularly to that of Messrs. Pontifex and Wood, by completely decompose the organic matter, but not so high which a ton of char is revivified every twenty-four hours.] as to partly fuse the bones and thus render them unfit for A new process, however, has been devised by Messrs. their applications. But a more economical process is Leplay et Cuisinier, which as a whole deserves the attengenerally adopted. It consists in introducing the crushed tion of refiners, though I am. aware that several of the bones into horizontal retorts, which are themselves in con- details of their process have been used for some time. nexion with condensers, the ends of which are brought The char which has served its purpose in the cylinders, under the retorts to assist by their combustion in the dis- instead of being removed, is treated at once by the followtillation of the animal matter. By this arrangement not ing processes :-It is first thoroughly washed, treated by only is char obtained, but oily matters which are used by steam to remove all viscous substances, then a weak solucurriers, and also ammoniacal salts employed in agricul- tion of alkali is allowed to percolate through the char, ture and manufactures. The extraordinary decolorating which removes saline matters and a certain amount of action of animal blacks may be considered as partly colouring matter, when it is further acted upon by weak chemical and partly mechanical-mechanical because it is hydrochloric acid, which, in removing a certain amount of proved, by some interesting researches of Dr. Stenhouse, the lime salts, liberates the colouring matter; the char is to which I shall refer further on, that the action is due to again washed with weak alkali to remove the remaining the minute division of the carbon and the immense surface colouring matter, and lastly the decolorating power of the offered by its particles to the colouring matter, char being black is restored by passing through it a solution of bicomposed of 90 parts of mineral salts to 10 per cent. of phosphate of lime. It is to be hoped that the high praise carbon. On the other hand, the action is proved also to bestowed upon this process on the Continent may induce be chemical, by the fact that water will not remove the our manufacturers to try it, as they would obtain two discolouring matter, whilst a weak solution of alkali will distinct advantages by its use. First, the economy of solve it. Dr. Stenhouse's valuable researches not only operating at once upon the black and restoring its proillustrate fully this fact, but also prove the possibility of perties without removing it from the cylinders. Secondly, producing artificially substitutes for bone-black. In 1857 the prevention of the noxious odours given off during the he published a paper describing the production of an arti- revivification of char by the ordinary methods. It is ficial black, called by him aluminised charcoal. This he interesting to note one of the results of the different emobtained by mixing intimately and heating finely pul- ployment of char in this country and on the Continent. verised charcoal and sulphate of alumina, when he ob- In England the wear and tear in sugar refinery is contained a powerful decolorating agent containing 7 per cent. stantly repaired by the introduction of fresh char, and of alumina, and well adapted for decolorating acid solu- there is no spent or old char for sale. In France, on the contrary, owing to the great impurities in their beet-root sugar syrups, and to the use of blood in refinery, the char becomes rapidly clogged with organic matter, and is so completely animalised, that its value as a manure exceeds what the char originally cost the refiner. The result is that French "spent" char is annually exported to the French colonies to the amount of 120,000 tons, and is there used as a manure to promote the growth of the sugar cane. So important is this article of commerce considered, that the French Government have appointed special analytical chemists to determine its value for the trade. Phosphorus.-I am now about to call your attention to one of the most marvellous and valuable substances ever discovered by chemists. In 1660, Brandt, a merchant of Hamburgh, discovered a process for obtaining phosphorus from putrid urine; but though he kept his secret, a chemist named Künckel published the mode of obtaining it from this fluid. A hundred years later, Gahn discovered the presence of phosphorus in bones; and Scheel shortly afterwards gave a process to obtain it therefrom. The process devised by this eminent chemist was shortly afterwards improved upon by Nicolas and Pelletier, and their method was so completely worked out by Fourcroy and Vauquelin, that it is still the process used in the present day. The preparation of phosphorus consists of four distinct operations:-1st, 80 parts of thoroughly-calcined and pulverised bones are mixed with 80 parts of sulphuric acid, sp. gr. 152, to which is then added 400 parts of boiling water; 2ndly, after a few days the clear liquor, containing bi-phosphate of lime, is removed from the insoluble sulphate, and evaporated until it has the specific gravity of 15; 3rdly, this liquor is mixed with 20 per cent. of finelypulverised charcoal, and the whole is dried at a moderately high heat; when, 4thly, it is introduced into an earthenware retort, placed in the galley furnace, and, on heat being slowly applied, phosphorus distils, and the operation is continued at a high heat for several days. It is, however, necessary that the phosphorus thus obtained should be purified, and this is effected by melting the phosphorus under water, and pressing it through a chamois skin. It is then boiled with caustic alkali to remove other impurities, but what is still better is to heat the phosphorus with a mixture of bichromate of potash and sulphuric acid. The phosphorus thus purified is drawn through slightly conical glass tubes by the suction of a caoutchouc pouch, or is allowed to run, by an ingenious contrivance, into tin boxes. As will be seen by the following formula, the manufacturer only obtained from the bones one-half of the phosphorus they contain: z(PO,,3CaO) + 4SO,HO=z(PO,CaO,2HO)+4(SO,CaO). Bone phosphate Sulphuric Acid phosphate of lime. acid. of lime. Sulphate of lime. July 9, 1864. stream of hydrochloric acid is made to percolate, and, as shown above, chloride of calcium, hydrogen, carbonic oxide, and two proportions of phosphorus are produced. (The process of Fleck was also described.) Phosphorus prepared and purified by the above processes is a solid, semitransparent body, having a sp. gr. 183, fusing at 110'5° F., and boiling at 550°. It is so inflammable that it ignites in the open air at several degrees below its fusing point; but Professor Graham made, some years ago, the interesting observation that this slow combustion of phosphorus could be entirely checked by the presence of certain combustible vapours. Thus he found that one volume of vapour of naphtha in 1820 of air, or one volume of vapour of oil of turpentine in 4444 of air completely prevented the spontaneous combustion of phosphorus. Further, phosphorus presents the curious property that, if heated to 160° F. and suddenly cooled, it becomes black, and if heated to 450° or 460° for several hours it becomes amorphous, and of a dark brown colour. This allotropic state of phosphorus, first noticed by Schrotter, has enabled it to render great service to society, owing to its not being spontaneously inflammable (as, in fact, it only becomes so at a temperature approaching its point of fusion), and also to its not being poisonous, so that it can be substituted for common phosphorus in the manufacture of matches with great advantage. Lastly, owing to this brown amorphous phosphorus not emitting any vapours, those employed in the manufacture of chemical matches now avoid the risk of the dreadful disease of the jaw-bone, called phospho-necrosis. Notwithstanding the great difficulties attending the manufacture of this valuable product, Mr. Albright, of Birmingham, has, with praiseworthy perseverance and great skill, succeeded in obtaining it perfectly pure on a large scale, and at such a price as to bring it within the scope of commercial transactions. Chemical Matches.-Although I do not intend to enter at great length upon this subject, yet, as it is a highly important one, I deem it my duty to lay a few facts before you. The first application of chemistry to the discovery of a substitute for the old tinder-box of our fathers, was made in 1820, when the sulphuretted ends of matches were covered with a mixture of chlorate of potash, licopodium, and red lead, and the matches so prepared were dipped into asbestos moistened with sulphuric acid. In 1836, lucifer matches were first introduced, and the explosive matches were soon followed by the non-explosive ones. The composition of these matches is as follows:Non-Explosive. Explosive. 16" Sand Gum orglue 20 I • 20 20 6 The danger as well as the disease attendant on this manu- NEWS the amount of phosphorus used to a very considerable extent, so that the disagreeable smell of this substance is also avoided. But the greatest improvement that Messrs. Letchford have made is in what they call their hygienic matches, or lights, in which, for the first time, amorphous phosphorus is substituted for ordinary phosphorus, and in small quantities. The advantages of these matches cannot be overrated, for children can eat them with impunity, as amorphous phosphorus is not poisonous; they are not nearly so combustible, and, therefore, not so likely to cause accidental fires; and lastly, all source of injury to the health of those employed in the manufacture is removed. I cannot leave this subject without still drawing your attention to one or two important facts. Messrs. Hochstetter and Canouil, besides others, have lately introduced chemical matches free from phosphorus, which are stated to have the following composition : Peroxide of manganese Chromate of lead Gum arabic . 4 An important improvement in the manufacture of chemical matches is the reduction of the proportion of phosphorus to a minimum. This is effected by reducing the phosphorus to an infinitesimally minute division, by which the manufacture is rendered more economical, and the matches, when ignited, have less of the unpleasant odour of phosphorus. This division is accomplished by using a solution of phosphorus in bisulphuret of carbon, by which a saving of 18ths of the phosphorus is obtained. Another invention is that of Messrs. Puscher and Reinsch, who have proposed the employment of sulphide of phosphorus. Ivory. The lecturer, having given some details respecting the properties of ivory, said: I will now call your attention to the substitution of the following mixture for ivory tablets as applied in photography. Finely-pulverised sulphate of baryta is mixed with gelatine or albumen, compressed into sheets, dried, and polished; these sheets are ready for use in the same way as ivory plates. You are all doubtless aware that the nut of the Phytolephas macrocarpa, of the palm tree tribe, has for many years been used in this country as a substitute for ivory, and it may be interesting to you to be made acquainted with the two following facts, viz., that the nut is composed of— • 100 " 4 " 9 Total and Dr. Phipson has recently published a method of distinguishing this vegetable ivory from the animal one by means of sulphuric acid, which gives a beautiful purple colour with the vegetable ivory, but none with the animal ivory. Horn. The best quality of horns, and especially the beautiful ones obtained from the buffaloes in India and America, receive a great variety of application at the present day, owing to their great toughness and elasticity, as well as to their remarkable property of softening under heat, of welding, and of being moulded into various forms under pressure. To apply horns to manufacture they are treated as follows:-They are first thrown into water, and slight putrefaction commences, by which ammonia is produced, when the horn begins to soften. To carry this action further the horns are transferred into a slightly acid bath, composed of nitric and acetic acids, with a small quantity of various salts. When the horns are sufficiently softened, which requires about two weeks, they are cleaned and split into two parts by means of a circular saw, and these are introduced between heated plates, and the whole subjected to an intense pressure of several tons to the square inch. The plates may be moulds, and thus the horn may be compressed into any required shape. A great improvement has recently been effected in this branch of manufacture, which consists in dyeing the horn various colours. To accomplish this the horn is first dipped into a bath containing a weak solution of salts of lead or mercury, and then rubbing upon the horns impregnated with metallic salts, a solution of hydrosulphate of ammonia, when a black or brown dye is produced. Another method consists in mordanting the horn with a salt of iron, and dipping it in a solution of logwood. Of late very beautiful white fancy articles have been produced from horn by dipping it first in a salt of lead and then into hydrochloric acid, when white chloride of lead is fixed in the interstices of the horn, which then simply requires polishing. This lecture, as well as those which followed, were illustrated by numerous specimens and experiments. CHEMICAL GEOLOGY. A Course of Twelve Lectures, by Dr. PERCY, F.R.S. Delivered at the Royal School of Mines, Museum of Practical Geology, Jermyn Street. LECTURE XI.-Thursday, January 28. LADIES AND GENTLEMEN,-We will proceed this morning with the subject of coal. I endeavoured on the last occasion to explain that all varieties of coal, including peat and lignite, might easily be deduced chemically from woody tissue by the elimination of marsh gas, carburetted hydrogen, carbonic acid, and water. This might be rendered clear to demonstration by bringing before you a number of formulæ, but I trust you will take my word for the result, as a lecture of this kind is hardly the occasion for the discussion of such formulæ. Nitrogen is also found in coal. I know no exception at present. It generally exists to the extent of about 1 or 2 per cent. Sulphur, likewise, is always there, and it exists in several distinct states-as iron pyrites-bisulphide of iron, sometimes finely diffused through the coal so as scarcely to be visible, and at other times existing in thin lamine or small particles, or in nodules, and occasionally even as beds of one or two inches in thickness, or more than that. It is there as sulphate, the sulphur being in the form of sulphuric acid combined with bases,-as sulphate of lime, for example. It is also present in a state of organic combination, just as we find sulphur existing in fibrin or albumen on various azotised organic tissues. This, I think, has been proved to demonstration by analysis. We have examined coals, and determined the proportion of iron contained in the ash, and also the absolute amount of sulphur in the coal, and we find that occasionally there is much more sulphur than can be accounted for by the iron pyrites present. Further, we find that it cannot be explained in such cases by the existence of sulphates. It must, therefore, exist in a state of organic combination. All coal contains a certain amount of inorganic matter or ash, derived partly from the mineral constituents of the plants from which the coal has been generated, and also in part from earthy matters which have been washed in during the time of the formation of the coal. Accordingly, if we examine the composition of the ash of coal and that of the bed and roof of a coal-pit, we shall find that the ash has in many cases almost identically the same composition as the matters forming the bed and the roof. This has been very clearly shown by Mr. Taylor, who has given us several excellent analyses illustrative of the fact. The iron pyrites in coal is subject to spontaneous decomposition. It is oxydised by the action of moist air, and becomes converted into what is called misy-a yellow basic sulphate of sesquioxide of iron. If we open an old colliery, for example, we find little patches of these substances here and there. The combustion of iron pyrites generates much heat, and occasionally causes the spontaneous ignition of the coal-an accident occasionally attended with great loss, especially in the South Staffordshire district. I might here take occasion to observe that I am disposed to believe that there is another cause of spontaneous ignition similar to that which determines the spontaneous combustion of cotton waste-namely, the absorption of oxygen by coal reduced to a fine state of division. M. Marsilly, who has charge of a railway department in the north of France, has made some curious observations upon coal with reference to the presence of marsh gas in it. Certain coal-in fact, coal generally when exposed to a gentle heat, or even in vacuo, evolved inflammable gaseous matter, and also a little liquid matter-I will not say resinous, but reminding one of the odour of benzine, too small to be investigated at present. He says also that only certain coals evolved this combustible gaseous matter, and he has met with coal, from which only carbonic acid and nitrogen could be obtained. " Therefore," he says, "by the examination simply of a piece of coal in this way, I can at once state whether fire-damp will be found in a colliery or not." This accords, to a certain extent, with our experience. We know that there are certain coal-fields which are apparently free from fire-damp; but at present we are unable to explain the cause of the absence of carburetted hydrogen. There must, of course, be some local peculiarity to account for it; but, as far as I know, this point has not yet been the subject of investigation. The explosions which we hear of from time to time in ships laden with coal are due to the gradual escape of the carburetted hydrogen contained in the coal, its admixture with atmospheric air, and its subsequent ignition. With regard to the varieties of coal much might be said. I shall, however, content myself with very few remarks upon the subject. We have, first of all, the lignites-a very extensive series-which are not classed ordinarily by geologists as coal proper, inasmuch as they do not belong to the carboniferous series; but in many respects they very closely resemble coals, and chemically they certainly are coals, and some, if I mistake not, are identical in composition with coals from the true coal measures. These lignites vary much in external character-some, we find, presenting the appearance of wood, and others being so coallike that we cannot distinguish from true coal. Occasionally they are, more or less, schistose and earthy. Their colour varies from brown to deep black. They are all, more or less, brittle. Some of them are remarkable as containing a large amount of iron pyrites, which causes them speedily to weather, and various very offensive products are driven off by the distillation on burning of such lignites. You remember I pointed out one peculiarity which, I think, is deserving of your attention-namely, that lignites generally contain a large amount of water; and so far they approximate in character to wood. This is a point which has not been sufficiently dwelt upon, I think, by geologists. We have found sometimes 15, 18, or 20 per cent. of hydroscopic water. The lignite to the eye and to the touch will appear perfectly dry like a piece of dry wood; but yet on the application of a gentle heat all this water may be expelled, as in the case of wood. This water not being water displaced from combination may be reabsorbed by the exposure of the lignite to the air. I may mention to you the occurrence of magnificent lignites in Trinidad, about which a monograph has been written, together with a statement concerning their geology, by Mr. Wall, a gentleman formerly a student of this Institution. They are very remarkable lignites. The mineral pitch which has been produced there has been derived from those deposits by the application of heat. We have several distinct varieties of coal occurring in this country. First comes the large class of bituminous coals, which CHEMICAL NEWS, July 9, 1864. |