Müller and Vögel, jun., is interesting as possessing qualities, not only different from those of gelatine, but such as injure the quality of the latter when mixed with it. In fact, it gives precipitates with acetic acid, alum, persulphate of iron, and other salts; and as gelatine is often used in connexion with these substances, it is easy to foresee how these precipitates may interfere with its application. On the other hand, the quality possessed by this peculiar gelatine, may, I think, render it serviceable in the art of calico printing, for fixing colours, or as a substitute for albumen or lactarine. Thus, the solution of chondrine and acetic acid may be mixed with any of the new tar colours, and the whole printed, allowed to dry, and steamed; the acetic acid will be driven off, leaving the colour fixed by the chondrine on the fabric. Chondrine is prepared by submitting to the action of heat and water the cartilaginous tissue of animals or the bones of young animals.

Isinglass is obtained from the air-bag or swimmingbladder of several kinds of fish, especially those of the sturgeon tribe, and, although imported from various parts of the world, the principal supplies are from Russia, from whence the best qualities come, which bear the names of Beluga, Volga, or Caspian Sea leaf. Brazil, New York, the East Indies, and Hudson's Bay, also supply various qualities of this valuable substance. It also reaches this country in different states-viz., in leaf and in honeycomb, that is, the bag is cut open, cleaned and dried; and the quality called snow-bleached is enhanced in value by having been buried in the snow on the banks of the Volga for a long period, by which the isinglass is whitened. Pipes, purses, and lumps are bags which have been cleared but not opened; and a quality called ribbons is made by rolling the bag and cutting it into strips before shipping it to this country.

I shall now endeavour to explain to you how the beautiful preparations before you, for which I am indebted to the kindness of Mr. James Vickers, are obtained. The leaf bladder is first softened in water, and rolled out, under high pressure, into thin leaves, which may extend to several feet long; these in their turn are drawn under a number of revolving knives, making 1000 revolutions per minute, by which 6000 of the well-known fine threads are produced in every minute. This quality is chiefly used for culinary purposes. For commercial uses the purses or lumps above mentioned are chiefly employed. These are soaked in water for two or three days, cut open, certain useless parts removed, further softened, rolled, and cut into various dimensions, according to the requirements of trade, their chief use being the clarification of beer and other alcoholic fluids, for which gelatine cannot be employed, because it dissolves in water, whilst isinglass merely swells. The result is that the highly-swollen and extended mass, when poured into beer, wine, or other alcoholic fluids, is on the one hand contracted by their alcohol, and on the other hand it combines with their tannin, forming an insoluble precipitate, which, as it falls through the liquor, carries with it the impurities in suspension, and thus clarifies the fluid. As isinglass is very slow in swelling out in water, brewers employ an acid fluid for the purpose, but, strange to say, instead of using pure acetic acid, many of them take sour beer, and thus run the great risk of spoiling their sound beer. I have known instances of great losses occurring in this way, acetous fermentation having been thus spread through an entire brewery during the summer months. As a large quantity of gelatine, cut into shreds, in imitation of isinglass, is sold at the present day, it may be useful to know that detection is very easy by the following method:-Place a small quantity in hot water, in which gelatine will readily dissolve, whilst isinglass will do so very slowly. I cannot conclude the examination of this interesting class of substances without drawing your attention to the fact that osséine, gelatine, chondrine, and isinglass present marked differences in their

textures and general properties, although their chemical compositions may be considered identical, thus :Gelatine. Chrondrine. Isinglass.

Osséine. 50'4 6.5

50.0

50 61

50'56

6.5

6.58

6.90

17'5

15'44

17.79

26.0

27°37

24.75

Carbon Hydrogen. Nitrogen 16.9 Oxygen 26.2 Esculent Nests.-I must not omit to mention, in connection with this interesting class of substances, these curious gelatinous products, which are not only considered great delicacies in China, India, but even in Europe, where they realise from £3 to £7 per pound; considerable quantities are imported into England. It has long been a disputed question what is the chemical nature of the substance composing these nests, which are the product of a peculiar kind of swallow; but Mr. Payen, by his recent researches, has left no doubt in the minds of chemists that it is an animal, not a vegetable matter. In fact, it is a peculiar mucous substance, secreted by the bird, and composed of carbon, hydrogen, oxygen, nitrogen, and sulphur. Further, it is insoluble in cold water, but soluble in boiling, and differs from gelatine and isinglass in that it does not gelatinise as it cools.

Skins. Skin consists of two principal parts, one a mere film, called the epidermis, and the other constituting the bulk of the skin, and called the dermis. There are also found in skin a large quantity of blood-vessels, and a small quantity of pigment cells, which hold the colouring matter. Further, the skin contains a small amount of nerves and a number of glands, among which may be cited the sebaceous glands or follicles, which are intended to secrete the unctuous matter constantly accumulating upon the skin, and keeping it soft and pliable; then there are the perspiratory glands, which play a most important part in the physiological construction of the skin. These are so numerous that Mr. Erasmus Wilson has calculated that there are 3528 of them in a single square inch of human skin, so that in an ordinary sized body there are no less than 2,300,000 of these pores. But still the most important part of the hide for us is that called the "dermis." The skins of animals are commercially divided into three distinct classes. The hide is the name given to the skin of full-grown animals, such as oxen, horses, and buffaloes; and these are further sub-divided into fresh hides, that is to say, those which are obtained from animals slaughtered in this country; dry hides, that is, hides which have been dried in the sun, and which are principally imported from South America; dry salted hides, principally from the Brazils, where they are salted and then dried in the sun; and salted hides, which are preserved in Monte Video and Buenos Ayres by salting them, and which are shipped, embedded in salt, to this country. The composition of a fresh hide may be considered to be as follows:—

Real skin. Albumen.

32°53

1'54

0.83

7.60

57°50

A second class of hides is that called kips, which are skins flayed from the same kinds of animal as the foregoing, only when young. Thirdly, the term skin is applied to those of small animals, such as the sheep, goat, seal, &c.

I will now endeavour to give you an idea of the preparation which hides undergo to fit them for the art of tanning. These operations are four. The first consists in washing off the dirt from the hide, softening it, if a dried one, or removing the salt, if salted. The second has for its object the removal of the hair, which is effected by two or three different methods. The most usual plan is to place the hides in large vats, containing a weak milk of lime, for two or three weeks, care being taken to remove and replace

them every other day, after which time the hair is sufficiently loosened to be removed. A second plan consists in piling up the hides, allowing them to enter slightly into a state of putrefaction, and then placing them in weak milk of lime, so as to complete not only the loosening of the hair, but also the swelling of the hide, for lime also possesses that property. Another process, which is called the American, plan, is to hang the hides in pits for two or three weeks, keeping them at a temperature of 60°, and constantly wet, when the hair can be easily removed. Weak alkalies are sometimes substituted with great advantage for lime in the above processes, and this plan is certainly the best, as it does not leave in the hide any mineral residne, as is the case with lime, either in the form of an insoluble soap of lime or of carbonate, both of which are highly objectionable in the subsequent process of tanning, as they act on the tannic acid of the tan, facilitating its oxidation, and thereby rendering it useless. Depilation of hides is sometimes effected by the employment of weak organic acids; thus, the Calmuck Tartars have used from time immemorial sour milk for that purpose. In some parts of France, Belgium, and Germany, the unhairing of the skins is also effected by an acid fluid, produced by the fermentation of barley meal, which gives rise to acetic and lactic acids. To carry out this process, generally speaking, five vats are used. In the first the hides are cleaned; in the second they are softened, and the hair and epidermis prepared for depilation; and the third, fourth, and fifth are used to swell and give body to the hide. This operation, which is called white-dressing, does not work so well as lime for heavy hides, as it swells them to such an extent as to render them unfit to prepare compact leather. When the hair can be easily pulled off, the hides are placed on a convex board, called a beam, and scraped with a doublehanded concave knife, which not only removes the hair, but a large amount of fatty lime-soap and other impurities from the hides. The third operation consists in fleshing the hides, by shaving off all useless flesh, fat, and other matter by means of a sharp tool. The fourth operation is called swelling or raising the hide, the purpose of which is the following:-First, the removal of any lime or alkali which may remain in the hide; and secondly, to swell or open the pores of the hide, so as to render them better adapted to absorb the tannic acid of the tanning liquors. This is effected by dipping the hides in weak spent tanning liquors, or liquors which have lost the tannic acid, but which contain more or less of gallic acid, for not only do all tanning matters contain gallic acid, but its proportion is greatly increased during the operation of tanning, by a process of fermentation which goes on during that operation, and which converts tannic acid into gallic acid and a peculiar sugar.

The Tanning of Hides.-The old process of tanning consisted in placing layers of wet tan and of hides alternately, and after two or three months removing the whole from the pit and replacing the old by fresh tan. These operations were repeated until the hides were tanned, which took from eighteen months to two years, owing to the difficulty of the tannic acid reaching the interior of the hide. Of late years the process of tanning has been greatly shortened by treating the bark with water, and steeping the hides in the liquor, first weak and afterwards strong. By this means good leather can be obtained in the space of eight or ten months. More rapid tanning, but probably giving inferior leather, is effected by employing, in conjunction with, or as a substitute for, bark, a decoction of dividivi, valonia, myrobalan, catechu or terra japonica, gambir, &c. Many efforts have been made of late years to apply the laws of hydraulics, as well as several physical and physiological principles discovered by eminent philosophers, with the view of shortening the period of tanning, but as I believe that none of them have received the general sanction of the trade, I shall confine

CHEMICAL NEWS, July 16, 1864.

myself to giving you an idea of the most successful ones. The first attempt to acclerate the process of tanning consisted in forcing the tanning fluids into the substance of the hide by means of hydraulic pressure. Mt. Spilbury, in 1831, employed a process which consisted in making the hides into sacks, and plunging them into a tanning liquor, and as the fluid percolated through the skin into the interior of the bag the air was allowed to escape. By this means a certain amount of time was saved in bringing the tanning liquor in contact with the various parts of the skin. Mr. Drake soon followed in the same direction, his plan being to sew hides together, forming bags, which he filled with a solution of tan; and to prevent the distention of the skins by the pressure of the liquid within, they were supported in suitable frames; as the pores became gradually filled with tannin, artificial heat was applied to increase the percolation of the fluid. Messrs. Chaplin and Cox's process is also very similar to the above, the difference being that the tannin fluid is placed in a reservoir, and allowed to flow into the bag of hides through a pipe, the fluid being thus employed at pressures varying according to the height of the reservoir. The bag of hides is at the same time plunged into a solution of tannin to prevent excessive distention. Messrs. Knowles and Dewsbury have recourse to another principle to compel the percolation of the tanning liquor through the hide. To effect their purpose they cover vessels with hides, so as to form air-tight enclosures, and, having placed the tanning fluid they employ on the hides, the vessels are exhausted of air, and atmospheric pressure then forces the fluid through the skins into the vessels below. Mr. Turnbull's process, being an imitation of that used for tanning Morocco leather, need not be described. Attempts have been made from time to time to mineralise hides, that is to say, to substitute for tanning, mineral salts, as will be described in my next lecture, when speaking of the art of tawing skins. The processes which have attracted most notice in this branch of the art of preparing leather are those of Messrs. D'Arcet and Ashton, M. Bordier, and M. Cavalier. M. Bordier's plan is that of dipping hides in a solution of sesquisulphate of iron, when the animal matters of the hide gradually combine with a basic sesquisulphate of iron, rendering the hide imputrescible, and converting it into leather. M. Cavalier's method is to dip hides first into a solution of protosulphate of iron, and then into one containing alum and bichromate of potash. A chemical action ensues, by which the protosulphate of iron is converted into a persulphate, combining with the animal matter, and by its preservative action, together with that of some of the alum, the hide is converted into leather. I think, however, that I shall be able to satisfy you, from the results of many examinations of leather and hides which I have made, that there are good and sufficient reasons why most of these processes have necessarily failed. Inventors have been led to believe, by the statements of many eminent physiologists (as can be proved by reading some of the most recent works on that science), that skin is composed of blood-vessels, glands, &c., plus gelatine, and that if by any mechanical contrivance the tanning liquor could be brought into contact with this gelatine, the leather would be tanned; and many ingenious schemes have been devised, and much money expended, to obtain that result. The fact, however, is that there is no gelatine in skin, for if there were, when hides were placed in water, the gelatine would be dissolved and washed away. But what is supposed to be gelatine in the hides is in reality the isomeric substance called osséine, or one greatly resembling it. The great discovery to be made in the art of tanning, therefore, is that of a chemical or fermentative process, by which the isomeric change (that of the osséine into gelatine) may be rapidly produced, instead of by the slow putrefactive process which occurs in the old method of tanning. Further, I would observe that to convert a hide into leather it is not suffi

cient that the whole of its animal matter be combined with tannin, for the leather thus obtained would present two great defects: 1st, the hide would not have increased in weight, and the tanner's profits, therefore, would suffer; 2ndly, the leather would be so porous as to be useless for many of the purposes for which leather is required. The reason of this is, that when, after a period of several months, the osséine has been converted into gelatine, and this has become thoroughly combined with tannin, a second series of reactions is necessary to render the leather more solid and less permeable to water, and to increase materially its weight. These reactions constitute what is called feeding the hide, and are brought about by leaving it to steep in more concentrated tanning liquor for a considerable period; and this necessary process, beneficial to the wearer as well as to the producer, appears to me to be that which offers the greatest impediment in the way of shortening the period of tanning. The hides as they leave the tanning vat require several operations before they are ready to be used for soles, or to be curried for various commercial purposes. They are first slightly washed and placed in a shed to partially dry, and are then rubbed with a brush and rough stone on the face of the leather, or hair side, to remove any loose tanning material that may remain on the surface; but this rubbing is not applied to the back, as buyers attach great importance to the peculiar appearance called the bloom, which enables them to judge of the goodness of the tanning. The tanned hides are again slightly dried, and oiled on the face, and then submitted to the pressure of a roller passed over the surface, which has the effect of rendering the leather more flexible, and the surface perfectly uniform. These operations are repeated two or three times, when the leather is ready for soles. Before the tanned hides intended for shoe-soles are considered fit for that purpose, they must be slightly compressed and softened, so as to again diminish their permeability to water. This was formerly effected by beating with a hammer called the mace, but of late years this slow process has been superseded by compressing machines; and I believe those most appreciated in the trade were invented by Messrs. Cox and Welsh, and Messrs. Iran and Schloss.

THE minutes of the previous meeting having been read and confirmed. and the several donations to the library announced, the President informed the meeting that he had just received a letter of apology from Mr. Way, accompanied by a medical certificate, according to which he was sorry to have to announce the serious indisposition and consequent absence of the lecturer. Mr. Way had, however, kindly sent forward the notes of his subject, and had deputed Mr. Evans to address the Society in his stead; and he would, therefore, at once call upon Mr. Evans to favour them with the written communication.

The author commenced by referring to a sweeping condemnation of British agriculture and the waste of fertilising material pronounced by Baron Liebig, and promulgated a short time since through the medium of the Daily Telegraph and the Agricultural Gazette. In the number for November 15, 1862, of the last-named journal appeared a quotation, which was read to the meeting. It warned the British farmer against relying upon the foreign and artificial sources of manure which this country has secured to itself in guano and other native phosphatic materials, and pointed out the necessity of restoring to the soil those mineral ingredients of which it is constantly being robbed by the growth and removal of crops. The modern system of town drainage was that, of course, which came more

particularly under Liebig's censure, and the exhaustion of the guano beds had been dwelt upon as a contingency not altogether remote. Some of these assertions had been met in a work entitled "The National Laws of Husbandry, 1863," and the author proposed to deal with these and other points in "The Philosophy of British Agriculture." It had usually been considered necessary that the ingredients of the soil should be rendered soluble before they could be assimilated by the roots of the plant; but Liebig, on the other hand, maintained that this need not always be the case, that even solid substances had the power of entering the vegetable organisms by endosmosis; and, further, he believed that nearly all the carbon was taken in through the roots, and hence he insisted on the decomposition of humus as affording direct nutriment to the plant, whilst the advantage of employing nitrogenous compounds to furnish ammonia was equally problematical, About the year 1850, Mr. Way made some experiments which resulted in the discovery that arable soils had the power of absorbing ammonia, and even of fixing phosphoric acid and the salts of potash. By causing an aqueous solution of sulphate of ammonia to percolate through clay and sandy soils, it was found that the lime contained therein combined with the sulphuric acid and liberated ammonia, which then was retained by the soil, and if a solution of phosphate of soda was passed through a stratum of clay, both the acid and basic constituents became fixed by the earthy matters of the soil. It appeared probable that a class of double silicates was formed similar in constitution to the alums, but which were but sparingly soluble in water. The existence of silicate of ammonia had been denied by Liebig, but it was a fact, nevertheless, that some sort of combination was possible, for both sand and clay absorbed large quantities of ammonia gas, and when soluble ammoniacal salts were brought into contact with the silicates of alumina and lime (or soda) a portion of the ammonia became fixed by these felspathic minerals, and soluble compounds of lime passed through. In this way a large series of double silicates had been formed containing always silicate of alumina in union with a silicate of lime, magnesia, potash, soda, or ammonia. These compounds being then slowly acted upon by water presented to the roots of the plant a ready formed combination of various bases such as they required for successful development. The author admitted a clerical error in the table accompanying his paper of 1850 which had been pointed out by Liebig, but he felt much satisfaction in finding that the eminent German chemist had afterwards, in his "Theory and Practice," published in August, 1853, given him (Mr. Way) credit for having first called attention to the power possessed by clay in absorbing ammonia. This action Liebig considered perfectly analogous to that of carbon in condensing ammonia vapours, and in depriving vegetable substances of their colour and odour. Again, it appeared that the earthy bases in clay removed the nitric acid from saltpetre, the potash then forming a kind of double silicate. Every farmer knows how difficult it is to affect the sub-soil by a top dressing of manure, and hence the practice of growing cereals and deep-rooted plants, such as clover, in series, so that the land may not become unduly exhausted. The accusation made by Liebig to the effect that the British farmers were injudiciously growing more produce on the land than was warranted by the return of the mineral constituents in the shape of manure, was, in the author's opinion, fully and satisfactorily answered by a comparison of the state of agriculture at the present day with that of fifty years ago, and during the latter part of this interval much valuable fertilising matter had been lost by sewage. According to the data collected by the Rugby Sewage Commission, it had been estimated that every individual caused the loss of fifteen pounds of ammonia per annum, and reckoning the cost of this with proportionate quantities of phosphoric acid and potash at ten shillings per individual per annum,

34

it appeared that, with our present population, the country suffered a default by sewage at the rate of five millions sterling. Against this large expenditure, the author estimated the value of imported manures (guano and bone phosphate) at three millions per annum, leaving a deficit of other two millions. In conclusion, the author referred to the discussion pending between Baron Liebig and Messrs. Lawes and Gilbert in reference to the so-called "mineral theory," the first of these authorities maintaining that it was only necessary to restore to the land the ashes of the plants raised thereon; whilst, on the other hand, the English chemists advocated the liberal use of ammonia or of guano manures containing large quantities of nitrogen. It seemed to be almost a matter of indifference whether the hydrogen or oxygen compounds of nitrogen were thus employed; in other words, the nitrates were equally fertilising with ammonia. The author could not help remarking that Liebig had recently changed his opinions respecting the advantages of ammonia; this base could not properly be included amongst the mineral constituents of the soil, which were at one time said to be all important, but now that its use had become so general, the great German chemist wished it to be ranked by the side of potash and soda, and maintained that in an agri

cultural sense "ammonia is a mineral."

The PRESIDENT proposed a vote of thanks to the author for the elaborate paper with which he had favoured the Society; and to Mr. Evans for acting as the mouthpiece on this occasion. He felt sure that the members would participate in expressing their regret at the unavoidable absence through illness of Mr. Way. The subject was one of great interest to many of the Fellows then present, and he trusted the several points would be fully discussed. Mr. Alderman MECHI bore testimony to the interest and importance of the scientific matters brought forward by Mr. Way. He was himself a firm believer in the advantages to be derived from manurial irrigation. It must be remembered that our present system of house drainage is a comparatively recent invention, not more than twenty years old, and that forty years ago all the excreta of London was carried by barges as far as 150 miles along the coast for the benefit of the farmer. Every agriculturist well knows that if he takes crops off the land for two or three years in succession he cannot maintain the fertility of the soil without restoring the constituents which have been removed. The great question is, therefore, "How is it to be done?" If three millions of sheep were feeding on pasture and were not allowed to manure on the land, every one would say, what a great folly! The speaker had himself sent up to the London market ten acres' yield of peas, but they would not go far towards supplying London's want; in twenty-four hours all and many more would be consumed. It had, indeed, been estimated that 6,000,000 of acres were required to be cultivated in order to supply food for London alone. The rate of exhaustion of the land must then be very great, and so little manurial refuse is returned from the metropolis, that the farmer has to go abroad for his supply of manure to compensate him for this tremendous waste. A Committee of the House of Commons was now inquiring into some of these matters, and it has been calculated that ten inches of rain, or half a year's fall, in Essex, weighing 1000 tons, might be raised 300 feet for an expense of thirteen or fourteen shillings. These facts were promising, but Liebig objected to irrigation and land drainage, because the action of the water was supposed to remove the soluble salts. Mr. Way had, on the other hand, brought forward facts to prove that this was not the case, and the speaker strongly advocated the importance of directing capital to the great desideratum -viz., that of distributing, in the cheapest possible manner, the sewage waters of London over the cultivated lands of Essex and other counties in the neighbourhood of the metropolis. Now that 1000l. per yard was being expended upon railways, it must surely be worth while considering

CHEMICAL NEWS, July 16, 1864.

the policy of paying at the rate even of 30l. per yard for taking sewage into the country. A fall of five feet in the mile was sufficient in the case of the Loch Katrine water supply to Glasgow, and their works extended forty miles. The remarks offered by Dr. Voelcher and Dr. Gilbert will be reported in our next. The President then adjourned the meeting until after the recess.

LECTURES ON CHEMICAL PHILOSOPHY.-I. Delivered at the College of France, by M. A. Wurtz. (Continued from page 8.)

It is proper to say that Gerhardt changed the opinions he before held when he adopted typical formula. Up to that time he had considered as scientific only the crude formula: a chemical compound he had regarded as a whole, in which the elements were combined one with another without any particular arrangement. Hence came originally the name unitary system which was given to his doctrine. For example, he represented acetic acid as C2H4O2 and alcohol as C2HO, and he explained the formation of acetic ether as the union of these two bodies with the elimination of water.

Such was the way in which he at first interpreted chemical facts: it contrasts singularly with his second method, as we shall see without difficulty. The second method rests on a far more complete view of the phenomena, and a much more natural apprehension of the laws formation of acetic ether was explained—a formula which of chemistry. Compare the crude formula by which the explains nothing-with the typical formula, as under,— C2H CH HO 10+ H HT C2H2O

H

Here it is seen that nitrate of potash is formed in consequence of a double decomposition. According to Gerhardt, all salts are formed in a similar way; but this, as is easily proved, is an exaggeration.

We see now that the differences between the dualistic and the new theory are most clearly seen in the different ways in which they regard the constitution of salts. Dualism represents these as containing the elements of an anhydrous acid in juxta-position with those of an anhy. drous oxide, and this view seems to be supported by the decomposition which they undergo under the influence of the galvanic battery. It is said, for example, that sulphate of soda decomposes into sulphuric acid and soda, but it is

not so.

We know that sulphate of copper, when submitted to the current, decomposes into copper and SO. CuOSO, Cu+SO1.

=

quotes in support of his views, is exactly analogous The decomposition of sulphate of soda, which the qualist SO,,NaO decomposes into SO, and Na. (The proof of trode, an amalgam is obtained.) Afterwards, and by virtue this is the fact that when mercury is placed at the elecof a secondary action, Na decomposes some water, and forms NaO; at the same time SO, splits up into SO3, which appropriates the elements of water, and O which escapes. There is, then, a double and not a simple decom

*It is hardly necessary to point out that in these lectures the thought it necessary to indicate this by any change of typo, since the author adopts the equivalents C=12, 0= 16, &c. We have not context will sufficiently show the fact.

NEWS

position, and the formula SO Na better represents the facts of the electrolysis of sulphate of soda than the formula SO,NAO. But, the dualists will say, the proof that a salt may be composed of an acid and a base,-the proof of dualismis to be found in the fact that the vapours of anhydrous sulphuric acid, SO3, in passing over baryta, BaO, heated to redness, will produce sulphate of baryta, SO,BaO. Gentlemen, these syntheses prove nothing concerning the constitution of compound bodies.

We can produce sulphate of lead by combining the binoxide, PbO2, with sulphurous acid, SO2. Shall we argue from that that sulphate of lead, EO,Pb, contains SO2+ PbO2? Not at all.

Berthelot has produced formic acid by the synthesis of carbonic oxide and water. Shall we contend that formic acid contains carbonic oxide and water?

Carius has formed glycol, C2HO2, by combining olefiant gas, CH, with oxygenated water, HO; but no one has ever pretended that it would be correct to represent glycol as a binary compound of oxygenated water and ethylene. Again, Carius has obtained chlorhydric ethelenic ether by the synthesis of ethylene CH, and hypochlorous acid gas HCIO. On the other hand, I have formed the same compound by uniting oxide of ethylene with hydrochloric acid. We have thus for chlorhydric-ethelenic ether, the two dualistic formula

(C2H ̧+ HClO) and (C2H ̧O + HCl).

Which is correct?

These facts demonstrate that synthesis does not permit us to pronounce upon the atomic grouping of a compound. Although sulphate of barium is formed by the addition of the elements of sulphuric acid to the elements of oxide of barium, let us guard against drawing the conclusion that sulphate of barium contains ready formed and juxtaposed the elements of SO, + BaO.

account of a method of obtaining crystals from the amorphous gelatinous precipitates of these compounds. The amorphous precipitates produced by soluble phosphates in metallic solutions are not absolutely insoluble in the liquor in which they are found. If, then, by lowering the temperature the solubility is diminished, a part crystallises on the sides of the glass. When the temperature is raised again more of the gelatinous precipitate is dissolved; and thus by alternately heating and cooling the liquor, the whole of the precipitate may be obtained in crystals-in some instances of considerable size. In this way M. Debray has made a number of double phosphates.

M. Deville announced that he had obtained crystals of chloride of silver by sealing it in a tube with dilute hydrochloric acid, and leaving the tube exposed to a variable temperature for two years.

M. Bechamp described a "New Mode of Purifying the Heavy Oils from Tar, and a New Hydrocarbon from Coal Tar." The author finds that bichloride of tin will separate the bases of coal tar, and so allow a larger quantity of benzine to be distilled. The new hydrocarbon boils from 139° to 140°. M. Bechamp gives no further description at present. M. Lorin announced that he had obtained foramide by the distillation of formiate of ammonia.

Berzelius has said that the use of an hypothesis begets a belief in its truth, hides its weak sides, and prevents the mind from appreciating adverse facts-a profound observation which seems to me to be especially applicable to the dualistic notions held by the illustrious Swedish chemist.

ACADEMY OF SCIENCES.
July 6.

M. BECQUEREL presented a memoir "On the Preservation of Iron and Copper in the Sea." The author has borrowed from Davy the idea of protecting the metallic covering of ships by disposing bands of another metal (zinc) or an alloy around the vessel.

1301. John Baird and John McIntyre, Alexandria, Dumbartonshire, N.B., "Certain improvements in apparatus employed for clearing and bleaching textile fabrics." -Petition recorded May 25, 1864.

1374. William Clark, Chancery Lane, Middlesex, "Improvements in the mode of heating animal, vegetable, and mineral matters, whereby to effect their desiccation, vaporisation, decomposition, reduction, fusion, or volatilisation, and in apparatus for the same."-A communication from Henri Adolphe Archereau, Boulevart St. Martin, Paris.Petition recorded June 2, 1864.

1498. George Hyacinthe Ozouf, Rue St. Appoline, Paris, France, " Improvements in the manufacture and utilisation of carbonic acid, and in apparatus connected therewith."-Petition recorded June 16, 1864.

Apropos to this paper, M. Chevruel made some remarks on saponification and the neutrality of salts.

M. Hétet presented a paper "On the Chemistry of Cotyledon Umbilicus," in which he states he has detected the presence of trimethylamine.

M. Hugo Schiff read a paper "On some Phenic Derivatives of the Aldehydes."

A note by M. Debray "On the Production of some Crystallised Arseniates and Phosphates" gives an interesting

1509. John Henry Johnson, Lincoln's Inn Fields, Middlesex, "The manufacture of lyes or liquors applicable to the cleansing and bleaching of wool and other fibrous substances, as well as of textile fabrics."-A communication from Madame Rosine Saiglan Bagnéres' Paris, France.

1510. Thomas Townsend Coughin, Crucifix Lane, Bermondsey, Surrey, "Improvements in apparatus for compressing air or gases to be applied to various useful substances."

1513. William Henry Tooth, Rhodeswell Road, Stepney, Middlesex, "Improvements in furnaces or apparatus for generating carburetted hydrogen, carbonic acid, carbonic oxide, and cyanogen gases.'

1514. William Henry Tooth, Rhodeswell Road, Stepney,