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the last portions of the milk away. The pounding and the washing only occupy two minutes, and, as your readers will see, the butter is made with less labour than in any churn yet invented. In the winter, when the ground is frozen, the cream is buried in sand placed for the purpose in cellars, and a double bag is sometimes employed to make sure of getting no sand or earth into

the butter.

I should have told you some time ago of a trial here which will have some interest for English pharmaceutical readers. MM. Grimault and Co. import pepsine from London, and retail it as pure English pepsine. Something, however-trade and professional jealousy, it is alleged-caused a quantity of it to be seized by the police, and it was examined by M. Roussin, who reported that the pure English pepsine was nothing but starch, and MM. Grimault and Co. were accordingly condemned. That happened some months ago, but the affair has recently come before the courts again in the shape of an appeal by the defendants, and MM. Payen and Beaudoin have now examined the pepsine, and these gentlemen report it of good quality. M. Leconte also examined and reported favourably; but the Court, apparently not altogether satisfied, has ordered a fresh examination of the pepsine seized and other pepsine from London by MM. Fremy, Mailhe, and Reveil, and after they have reported the Court will give judgment.

Some experiments have recently been made by M. Tresca on Poissant's process for decorticating wheat before it is ground into flour. The corn is first slightly moistened, and then conveyed to a cylinder in which a sort of fan revolves with great rapidity. By this action the outer skin of the grain is detached, and is subsequently separated by winnowing. The flour is reported upon by M. Payen, who says that 100 of dry corn gives 89'6 of flour, which contains a considerably larger amount of nitro. genised principles, and is therefore more nutritious, than ordinary flour, but which will not make bread so white. He considers the flour will succeed well with Dauglish's process.

Writing of corn reminds me of the prospects of harvest, and may be it will interest some of your readers to know that colza and linseed have failed nearly everywhere in this country this year.

I extract some statistics on the subject of deaths by lightning from a note by M. Boudin. It seems that during the period 1835-1863, 2238 individuals were killed in France. The most in one year was 111; the fewest, 48. Among the 880 persons killed from 1854 to 1863, only 243 were females, which will be 26'7 per cent. In England the proportion of females killed is only 21.6 per cent. In many cases, M. Boudin says, when the lightning has fallen upon a group of people of both sexes, it has only killed the males and spared the females, which, I must say, is more gallant than fair on the part of the lightning. As a set-off to this conduct, I suppose, the fluid, when it has fallen upon a flock attended by shepherds, has only killed the sheep and spared the shepherds. M. Boudin states that there have been many instances of beeches struck with lightning, and that there are at least two examples of individuals struck more than once in the course of their lives; one man, indeed, was struck three times in as many different parts of his body, and another man was struck twice in his left foot. The statistics, I may add, prove the danger of standing under trees in a storm.

On Anomalous Degrees of Water Hardness. To the Editor of the CHEMICAL NEWS. SIR,-In consequence of my not having been present at the Chemical Society when Dr. Miller read his paper on "Potable Waters," I shall feel obliged by your inserting in your journal the following remarks corroborative of the novel and interesting statement made during discussion by Dr. Voelcker, to the effect that he had analysed a water which

NEWS

indicated a higher degree of hardness after boiling than before, Nearly twelve months ago I was requested by a client to examine a water with reference to its applicability to ordinary domestic purposes; and after examining it microscopically, as well as estimating the amounts of organic and inorganic matter which it contained, one of my assistants endeavoured to determine its hardness, which, to his astonishment and to my own, was increased instead of diminished by boiling. Concluding that some mistake must have been made, the experiments were repeated, both by my assistant and by myself; but we always obtained the same anomalous result, no matter whether the water was boiled for an hour or for a whole day. Several fresh preparations of soap-test were made with soap from different sources; sometimes the soap was dissolved in vinic alcohol, at others in methylated spirit. The various preparations of soap-test were graduated with solutions of chloride of calcium made and standardised at three different periods. Having taken these precautions to eliminate any error which might have been introduced into the previous experiments through the reagents employed, the attempt to ascertain the hardness of the water by means of the freshly and differently prepared soap-test was resumed. Still, it was observed that ebullition invariably caused an increase and not a diminution of the hardness of the water. Unfortunately, I am unable at present to furnish a more detailed account of the experiments above referred to, as the notes taken at the time of their being instituted are in the possession of my assistant, who is in Marburg. I trust, however, soon to receive the notes, and to be able to procure a fresh supply of the water to which they refer, in the hope that the results of a minute analysis will enable me to explain an anomaly which appears at present to be as inexplicable to Dr. Voelcker as to myself. I am, &c. RICHARD V. TUSON. Chemical Laboratory, Royal Veterinary College, June 28.

MISCELLANEOUS.

Non-Explosive Gunpowder.-The invention of Mr. Gale, which we mentioned last week, underwent a trial at Plymouth last week in the presence of several powder, when treated by Mr. Gale's process, could not be naval and military officers, and it was shown that the ignited by an ordinary slow match, or even by a red-hot poker. The invention at first sight would appear extremely valuable, but soldiers and sailors, we expect, will be startled at the idea of going into action with non-explosive gunpowder, although the explosiveness can be easily restored in two minutes.

Destruction of Scientific Property by Fire.—

On Thursday last a most calamitous fire destroyed over 30,000l. worth of literary and scientific property at the Wilkinson. We are, however, happy to state that the well known Auction-rooms of Messrs. Sotheby and valuable collection of photographic lenses, magic lantern slides, and the greater part of the other apparatus announced for sale in our advertising columns, is saved, having, at the time of the fire, been in the care of Mr. Highley, at 18, Green-street, Leicester-square. The sale will take place on Tuesday next, as originally fixed, but at the gallery, 21, Wellington-street.

ANSWERS TO CORRESPONDENTS.

Received-Oxamide; Report of Manchester Scientific Students' Association for 1864.

A Constant Reader writes:-"I saw lately, but cannot lay my bands on it, an artificial, quick mode of disintegrating the leguminous portion of leaves, and retaining the woody or fibrous portion as a skeleton. Can you or one of your numerous readers fu nish me with an efficient process? Also, a cotton yarn 'plated' or coated with silk

(by a process analogous to plating) was, and probably is now, used in glove manufacturing (also lace), evidently not coated from an etherial solution. Can you inform me the process?"

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On a Volumetric Analysis of Superphosphate of Lime, by GEORGE JONES, F.C.S.

IT has for some time been a desideratum of analytical agricultural chemists, and especially of those connected with the manufacture of artificial manures, to be enabled by a more speedy method than the one generally pursued to arrive at a correct estimation of the amount of phosphate of lime existing in a soluble state in the socalled "superphosphate." I have therefore been led to attempt a series of experiments upon a process of volumetric estimation, by the use of a standard solution of ammonia; but at the onset I experienced some difficulty in arriving at any satisfactory result in consequence of the existence of the free or uncombined sulphuric acid, which is invariably present in ordinary commercial superphosphate, it being impossible to present an alkali without precipitating the phosphate of lime.

:

The process I therefore adopt is the following :Having taken 100 grains of the sample for analysis, it is first of all well mixed with about 50 grains of finely powdered litharge, and introduced along with a small quantity of distilled water into a flask, and boiled for

about fifteen minutes. The whole is then made up with distilled water to 7000 grains (one deci-gallon), agitated well, and thrown upon a filter. I then take of the filtrate, by the use of a pipette, 1400 grains (200 septems) equal to 20 grains of the sample, and add thereto a little chloride of calcium solution, and 200 septems of the standard solution of ammonia; it is then made up with distilled water to a known bulk-say 2000 grains, agitated well, and filtered.

A 1000 grains pipette of the filtrate will therefore represent exactly 10 grains of the sample, and in this I now proceed to test for ammonia, added over and above that required to separate the phosphate of lime in the sample. Two equivalents of ammonia being required. for every equivalent of the tribasic phosphate of lime precipitated. Thus

CaO,POs,+2CaCl+zNH_O=(CaO),PO, and 2NH C1. The standard solution of ammonia I am in the habit

of using contains in every septem or of real ammonia, and I employ also a standard solution of hydrochloric acid, 50 septems of which require 292 of the standard ammonia for neutralisation.

In order, therefore, to estimate the excess of ammonia added to the liquid, I first add 50 septems of the standard acid, and then test with the standard ammonia, using, of course, a solution of litmus. Supposing, therefore, that 255 measures or septems of the standard ammonia are required to effect a complete neutralisation of the liquid, then say-292-25537, and 100 (the number of measures previously added) - 37- 63 measures of standard ammonia required to precipitate the phosphate of lime, and equal to 6'3 per cent. of real ammonia.

Therefore as

z(NH,)(CaO),POs per cent.

34: 155 :: 63 to x = 28 72 p.c. of phosphate

of lime.

By the use of the oxide of lead, the free sulphuric acid of the sample is not only neutralised but separated as insoluble sulphate, leaving the solution but slightly acid, and only from the acid phosphate. By repeated trials upon samples of known composition, I have never found this process to fail. It is both simple and accurate, and VOL. XII. No. 293.-JULY 14, 1865.

the time occupied from first to last is barely one-fourth of that required by the ordinary gravimetrical method.

June 27.

On the Easily Fusible Alloys of Cadmium, by
CARL RITTER VON HAUER."

THE alloys were made by fusing the ingredients in a covered porcelain crucible at the lowest possible tempe rature. After stirring with a glass rod, the fused mass was poured upon a cold metal plate, where it instantly solidified. The specific gravity and the melting point were determined after the alloy had been so melted and cooled two or three times. In the two or three fusions a partial oxidation of the metals takes place, which occasions a slight alteration in the equivalent proportions, and which it is almost impossible to avoid. The melting point was determined under hot water, and also by placing a thermometer in the fused mass without water. Under water the alloys quickly oxidise. They have also the property of becoming pasty below their proper melting point, which may lead to error in the determinations. The author's determinations were made when the alloy was really fluid.

The specific gravity of the metals experimented with were as under; the equivalent numbers are also given for the calculation of the proportions

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56

58.

11.350

103'7

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9'708 210

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Cd, Sn, Pb, Bi 9'725

9.666

+0'059

67.5°C

65.5°C

Equivalent proportions.

Cd, Sn, Pb, Bi, 9'685 9'652 +0.033

The above shows that some contraction of the metals takes place, but the smallest contraction is combined with the lowest melting point.

Lipowitz states that an alloy composed of three parts by weight of Cd, 4Sn, 8Pb, and 15Bi melts at 60° C.; but the author of this paper observes that such a compound only becomes perfectly fluid at 70° C.

The melting point of an alloy of two parts Cd, 3Sn, 11Pb, and 16Bi is still higher-namely, 76.5° C. The following mixtures had the same melting pointOne part by weight of Cd, 2Sn, 3 Bi Two parts. One part

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DR. R. MALY shows that formic acid is obtained under various circumstances when nascent hydrogen and carbonic acid at the moment it is set free, come together in the presence of a powerful base. A large proportion, for example, is procured when sodium amalgam acts on

a solution of carbonate of ammonia. The acid is also

found, but in smaller proportion, when finely granulated zinc, carbonate of zinc, and caustic potash are boiled

* Abstract from Journal für Prakt. Chemie, vol. 94, P. 436.

together, in which case the nascent hydrogen simply causing the eyes to water, and which have already been seizes upon the carbonate of potashobtained in the oxidation of alcohol and ether by platinum black. This black, under other conditions,

€02+H2+KHO=CHKO2+H2O.

The first reaction is, perhaps, capable of general appli-will give acetic acid, and here between platinum black cation for the preparation of homologues of formic acid, if, instead of carbonate of ammonia, the carbonates of methylamine or ethylamine, &c., are employed.-Journal fur Prakt. Chemie, vol. 94, P. 442.

Researches on Acetic Fermentation,* by M. PASTEUR. IT is a well known fact that wine, beer, and cider exposed to the air turn sour, and it was long since proved that this phenomenon was due to the alcohol of these liquids being transformed into acetic acid; but what part does the air play in this combustion, through what intermediary state of transformation does the alcohol pass?

5000

Acetic fermentation is always produced by the exclusive influence of an organism-the mycoderma acetione of the most simple vegetables, consisting essentially of frames of articulations slightly compressed towards the middle, measuring about th of a millimetre in diameter, and double that in length. However much charged with albuminoid matter, no alcoholic liquid has ever been known to give the appearance of acetification without the presence of this mycoderm. On the contrary, if a trace of the mycoderm is spread on the surface of an albuminoid liquid, alcoholic or slightly acid, it is immediately seen to develope, extend like a veil over the surface, and by a correlative action the atmospheric oxygen in contact with the liquid disappears and the alcohol acetifies. It is not essential for the liquid to contain albuminoid matters; provided the mycoderm finds there besides the alcohol a small quantity of alkaline and earthy phosphates, it will live and its action be the same as before; and this identity proves that the albuminoids which have been employed were merely nourishment for the ferment, and not the ferment itself. If in the actual process of vinegar making, acetification takes place without the previous spreading of the mycoderm, it must have been without the knowledge of the experimenter; it is this organism which forms the gelatinous mass which was formerly, with a vague idea of the truth, called mother of vinegar; it is this which by spreading over large surfaces of the beechwood chips used in the German process produces acetification. By pouring an alcoholic liquid on these chips, well washed and scoured, and thus deprived of the ferment, no trace of vinegar is obtained; but, the circumstances being favourable, acetification is produced by depositing a little of the mycoderm on the surface of the chips, where it rapidly developes.

While alcohol is present the small vegetable produces acetic acid; but what happens if the alcohol is wanting? M. Pasteur shows that the vegetable can in this case bring its burning action to bear on the acetic acid itself, and reduce it to the state of water and carbonic acid. This effect seems to be produced only when no alcohol is present, when there is alcohol the combustion is effected by preference on it.

Such is the action of the mycoderm under the ordinary conditions; but it sometimes alters, and having no longer the same appearance or the same consistence, its action is different. It is then incapable of effecting the combustion of the alcohol to the acetic stage, and gives intermediary products with a suffocating odour, and

* Annales de l'Ecole Normale, i.

and mycoderma vini there is a resemblance of effects from which it would be unsafe to infer a resemblance of causes. The only inference to be drawn is that both are means of transporting the oxygen of the air on to certain combustible matters.

For the production of acetification it is necessary that the mycoderm should be at the surface of the liquid; the process is arrested by submersion, and only recommences on the formation of a fresh film on the surface. and not a trace of this gas enters the liquid through it. The absorption of oxygen by this film is complete, When there is, as in Orleans' vinegar, a large quantity of small eels-animalculi needing air to support life-a curious contest takes place between them and the mycoderm, the latter tending to engross the whole of the surface, while the former combine all their efforts to submerge it and expose the liquid in which they live to free contact with the air.

The complete study of the manner in which this ferment acts and of the last interesting particulars will, perhaps, cause some progress to be made in the industrial preparation of vinegar; but the study of possible improvements must be left to the manufacturers.

THE

DUBLIN INTERNATIONAL EXHIBITION. By CHAS. R. C. TICHBORNE, F.C.S., F.R.G.S.I., &c. (Specially Reported for the CHEMICAL NEWS.) (Continued from page 6.)

Two complaints have been forwarded to the writer that he has passed over, in silence, cases in the Exhibition which deserved notice. The writer acknowledges, in a degree, the justice of the complaints, but then it must be taken into consideration that it would be perfectly impossible to enter into particulars of every case exhibited in a limited number of articles. Nor would such articles possess interest for the readers of this journal. The plan followed out has been to dwell upon exhibitors who would best represent a class, also to notice anything new which might occur amongst the others. It has been the endeavour of the author, as far as possible, not to touch upon a beaten track, but to place before the readers any little novelties which have been brought forward by this Exhibition, and will, therefore, not be found in any other report. At the conclusion a complete list of the chemical exhibitors will be given, this being all that space will permit.

Perfumery. — The perfumery department is well represented by Piesse and Lubin, Rimmel, and other well-known firms. The first-named house shows some very novel scents, but scents are so much a matter of taste that, to carry out Dr. Piesse's theory, what one person may consider a very recherché odour another may consider a regular flat 7th unresolved, but he may easily resolve the discordant feeling by turning to one which accords with his ideas. Dr. Piesse has many novel ideas upon the subject of perfumery, and one of the most important of them he submitted to the Royal Horticultural Society some short time since. The commercial importinferred from the following statistics:-The entire proance of the cultivation of flowers for perfumery may be cess of growing flowers for the process of enfleurage is carried on in the valley of the Var, in the extreme south

of France, bordering upon Italy-that is to say, from Nice to Cannes and rising to Grassa. This area comprises about 115,200 acres. All flowers, the olive and the vine, thrive here to perfection. The flower harvest of the district of Cannes alone gives the following annual supply-Orange blossoms, 1,475,000 lbs.; roses, 530,000 lbs. ; jasmine, 100,000 lbs; violets, 75,000 lbs.; tuberose, 24,000 lbs. ; jonquils, 5000 lbs. This does not include Nice and other districts. The value of these flowers is from 2d. to 2s. per pound. Now, says Dr. Piesse, no tree is so profitable to the flower farmer as the orange, and emigrants to any of our warm colonies should make a note of this, and fix on their memory that the leaves of the orange yield an otto worth 3s. an ounce, that the flowers yield an otto worth 10s. an. ounce, that the blossom also yields by enfleurage a fat worth 8s. per pound, that the rind of the fruit yields an otto worth 128. to 16s. per pound. There is a fine orangery near Sydney, the property of Richard Hill, Esq., so that we may soon expect in the markets of Britain the produce of this plant from one of our colonies. Queensland, Western Australia, Southern New Zealand, and Jamaica may take the hint, according to Dr. Piesse.

There is nothing new in the way of artificial flavouring essences. A few specimens of essence of pine (butyric æther), jargonelle pears (acetate of oxide of amyl).

Paraffine, Wax, Illuminating Oil, &c.-There are certain names which are intimately connected with specialities. We find two such, represented by two of the finest cases in the Exhibition; placed one each side of the nave, they stand like another Gog and Magog. Paraffine is now extensively manufactured, and the process of palm oil distillation will soon be equally disseminated. But Mr. Young's name is so associated with the former, and Price's with the latter, that one cannot pass over their cases without paying a passing tribute. Paraffine has been practically separated from resin, petroleum, fossil oils, peat, and coal. The last two have been the most prolific source of this beautiful product, whilst Mr. Young, by his slow process of distillation direct from coal, has certainly brought the method of manufacturing paraffine to the greatest perfection. When the Exhibition opened Mr. Young's case contained magnificent specimens of castings in paraffine. These included a colossal bust of Sir Walter Scott and sundry statuettes. Now, these strikingly illustrate the applicability of this "solid gas," as Liebig calls it, to the moulding of candles, the contraction of the melted paraffine being comparatively very slight, but sufficient to make it leave the moulds efficiently. It is, in fact, more suited to this kind of work than even spermaceti, wax, or stearine. There can be no doubt that before long the paraffine will be the candle par excellence. Its beautiful appearance, clear light, and cleanliness will no doubt in time establish its value. A strange result was produced in Mr. Young's case during the late fine weather. The sun's rays were so strong that most of the figures were partially melted, and found on one occasion in anything but a perpendicular position. This will give us a decided impression of the temperature of such buildings on a fine day, when we take into consideration the fact that pure paraffine melts at 60° C., according to Dr. Hofmann's report. This was procured by the following process, which is the one ordinarily used:-The mass of crude paraffine is subjected to hydraulic pressure, first in the cold and afterwards with the application of heat. The object of this last operation is to remove all hydrocarbons having a lower melting point than 40° C. For this

purpose there are placed in the horizontal presses between each pair of paraffin cakes hollow plates, through which water of 32°-40° C. is made to flow. In this way the hydrocarbons in question are fused and squeezed out. The pressed paraffine is now heated to 150° C. either over a fire or by means of steam, and the melted mass is mixed with 2 per cent. of concentrated sulphuric acid, by means of which all the hydrocarbons not being paraffine are carbonised. It is then carefully washed with hot water, and after cooling is mixed with the best colourless photogen (light mineral oil), and introduced into iron jacket cylinders, in which it can be kept warm, and where it is filtered through animal charcoal. By treatment with superheated steam the photogen is again completely separated from the paraffine. The paraffine manufactured in this manner is said not to bend when exposed to a temperature of 30° C.

In spite of the care expended upon the purification of paraffine, it is rarely that two samples can be procured so as to have a constant melting point. In many of the cases beautiful specimens of coloured paraffine candles are shown, and we believe that the coal-tar colours have been used for this purpose. It has lately been pointed out that the fatty acids form salts with rosaniline of a intense tinctorial power. We can well understand that these fatty salts would be applicable to the colouring of candles, palmitic, stearic, and oleic acids form salts with rosaniline, and the writer has verified the reaction with chrysaniline. He has no doubt that all the colours could be used for this purpose by varying the manipulations. From the small quantity requisite, and the organic nature of the pigments, the advantage in reference to its non-interference with the illuminating effects must be evident. The pigments in ordinary use--viz., verdigris, vermillion, chrome yellow, &c., are certainly not very desirable in this respect.

In connexion with the present case, we must mention the interesting case of Messrs. J. and C. Field, of Lambeth, one of the original manufacturers of paraffine candles. They also invented the self-fitting candles. But a still more important invention seems to have originated with them-viz., the plaited wicks, which are now universally used throughout the world. The wellknown night-lights seem to have been their invention, the first of them being made of wax. As this is essentially an age of art, we are not surprised to find that even candles are made to bear designs upon their surfacealthough they are things like flowers, made only to look gay for a brief space. Some of them, though most gaudy, are wanting in taste; but, on the other hand, there is a style of decoration, generally in the floral way, and painted in very subdued tones, which is beautiful in the extreme. The paraffine is particularly suited for this kind of decoration, as it presents such a pure translucent background to the colours. There are some very fine specimens exhibited by Messrs. Taylor and Co., Leith, and Rathborne and Co., Dublin; the latter firm being, we believe, the only manufacturers of paraffine candles in Ireland. The process by which this effect is produced is simply a matter of transferring the painting, which is first executed upon rice-paper in gum and colours, to the surface of the candle. Messrs. Rathborne and Co. are also bleachers of wax, and exhibit a specimen of pure wax. This article, it is almost needless to say, would be almost unsaleable as a commercial product in the present day. The ordinary white wax always contains spermaceti, or some other substance which gives it its white translucent appearance.

We think we are right in stating that Price's Patent

Candle Company at one time worked Rangoon naphtha for paraffine; but what they are more celebrated for is their process of distilling palm and other oil by which that substance is split up into its components, glycerine and the fatty acids, the latter being used in their candles. It was this firm that placed pure glycerine within the reach of the commercial public; and we will even go further, and say that, until they produced it, that substance was unknown. It is really wonderful to find the number of useful manufactures to which it has been since applied.

Lately distilled glycerine has been found in the market at various prices, some of it very good, and some equally bad. A German specimen which has come into the possession of the writer has evidently been decolorised with chlorine. For most of the applications of glycerine this would be very undesirable, whilst very few samples will be found to have the specific gravity of Price's.

Price's glycerine, concentrated upon a
water bath.

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Price's glycerine, as met with in com

merce •

German glycerine, very firm and fine specimen

Common German glycerine
English plaister glycerine

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Sp. gr. at 60° F.

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1.256

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1°253

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I'173

I'239 I'120

It is even necessary, therefore, to take the specific gravity into consideration in connexion with the price. One vile specimen, said to have come from the Continent, was examined by Mr. Draper, and found to consist of nothing but uncrystallisable sugar. This firm has in their case candles, coro-oleine, coro-stearine, specimens of wood shavings used in night-lights, in order to escape the paper duty, 160 cuts to the inch board, lubricating oil from Rangoon, petroleum, palm nuts, palmitic acid, &c.

Mr. Hutchinson exhibits some fine specimens of carbonate and bicarbonate of sodium-so-called crystals of bicarbonate of soda. Of course it is understood that they are pseudomorphous, retaining the rhombic form of carbonate of sodium; they are very beautiful and interesting objects; also some very fine specimens of

caustic soda are exhibited.

PROCEEDINGS OF SOCIETIES.

ON THE PRESENT STATE OF THE CHEMISTRY OF GAS LIGHTING.

By HENRY LETHEBY, Esq., M.B., &c. Delivered at Birmingham, before the Society of Gas Engineers.

(Continued from page 10.)

And now, in reviewing the facts which have been brought before us in an examination of the several hydrocarbons found in coal gas, the conclusions are-

1. That they belong to different groups, or series of compounds, in which the proportion of carbon and hydrogen rise by successive increments of 2 + 2, and that the amount of hydrogen in them progressively decreases. In the Marsh gas series, for example, the proportion of hydrogen is always two more than the carbon, thus:Marsh gas, or Methyl-hydride, CH4; Ethyl-hydride, CH; Propyl-hydride, CH.; Butyl-hydride, CH10; Amyl-hydride, C10H12, &c., all of which are found in the petroleums.

In the next series, the Alcohol radicals, which may or may not be present in coal gas, the praportion of hydrogen is only one more than the carbon, thus:-Methyl, C2H ̧;

NEWS

Ethyl, CH; Propyl, CH; Butyl, C.H,; Amyl, C10H11, &c.

In the third series, which are the chief constituents of coal gas, the Olefiant gas series, the proportions of carbon and hydrogen are equal, thus:-Methylene, C2H2; Ethylene, CH; Propylene, CH; Butylene, CH,; Amylene, C10H10; Capryolene, C1212, &c. portions less; and in the Benzol series it is six proporIn the next compound, Acetylene CH2, it is two protions less, thus :-Benzol, C12H6; Toluol, C14H8; Xylol, CiH10; Cumol, CH2; Cymol, C20H12, &c.

And, lastly, in the Napthalin series it is at least twelve proportions less.

2. We notice that the illuminating power of these hydrocarbons rises in proportion to the amount of carbon contained in a given volume of them-marsh gas being the weakest and naphthalin the strongest.

3. We perceive that their weight, or specific gravity, rises with their photometrical value-marsh gas being only about half as heavy as atmospheric air (o 5531), and naphthalin four and a-half times (442); so that, if accidental impurities were not present in coal gas, the specific gravity of it would furnish a good indication of its quality.

4. We remark that all the richer hydrocarbons, excepting acetylene and naphthalin, are easily decomposed by heat, carbon being deposited, and a weaker quality of gas -generally marsh gas-produced. It is manifest, therebear contact with the red-hot walls of the retorts; and fore, that these important constituents of coal gas will not the practical conclusion from it is that they should be swept out of the retorts as quickly as possible, and that the temperature of the retorts, especially of the upper parts, should be as low as possible; in fact, the destruction of these bodies is not by the temperature to which the coals are subjected, but by the heat of the upper parts of the retorts upon which the distilled gases and vapours impinge.

5. We have observed that, with one exception (marsh gas), all these hydrocarbons are freely absorbed by chlorine, bromine, and strong sulphuric acid; and that in each case a very similar set of compounds is formed, Dutch liquor being the homologue of the haloid compounds. This indicates the difficulty of determining the photometrical value of gas by the amount of condensation with chlorine or bromine; for by such a process we have no knowledge of the particular hydrocarbon condensed. In my own experiments I find that the condensation may be very different, even when the gases examined have the same illuminating power; and, conversely, we may have the same amount of condensation for gases of very different illuminating powers: the number, therefore, 325, which is sometimes taken as the co-efficient of power, is altogether unreliable.

6. We notice that all the richer and more condensible hydrocarbons are condensable by cold, and, therefore, that gas should not be subjected to a cold of 32°, or even much below 50° Fahr.

7. It is a fact that water has little or no influence on any of the hydrocarbons, except acetylene; and as this exists in gas only to a very small extent, there is little or no danger from a copious washing of the gas before it goes to the purifiers.

8. It is worthy of remark that the hydrocarbons are freely absorbed by oils, and by vulcanised india-rubber tubing. This circumstance should be taken into account flexible tube of about 30 feet in length will reduce the in testing the illuminating power of gas, for I find that a power of a weak gas to the extent of nearly 25 per cent.

9. It is not an unimportant fact that these hydrocarbons consume very different proportions of oxygen, and, therefore, vitiate very different proportions of atmospheric air; and, again, the explosive power of coal gas, when mixed with air, is much affected by the proportions of the richer

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