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Nov. 3, 1865.
Correspondence-Miscellaneous.

217 most of the phenomena arising from heat and combustion. more difficult case, the practicability of giving a sufficiShould there be a theory advanced as original accounting ently accurate motion to the rod and drum, where the for the action of flame, fire, combustion, &c., upon electro-correctness of registration would depend on this; also the magnetic laws, they have all been anticipated, and they variation of interval introduced by the difference of time will only be a revival of rejected theories, but in a further taken up by the movement of the rod before coming into stage of development than they have hitherto been. The contact with the mercury; correction for depression, &c. author above quoted imagines there to be an electric Should any one think this suggestion worthy of their atmosphere surrounding all bodies, and it is by disturbing notice, and succeed in practically carrying it out, I should their equilibrium that the phenomena of electricity are be glad to hear from them, and would only ask whatever produced, and he instances the fact that, to cause the credit may be due for the invention. electricity of an electric (plate) machine to be made mani

I am, &c. EDWARD CROSSLEY. fest, it must be excited by friction which the conductor Park Road, Halifax. conveys to the Leyden jar, and therefore the plate is for the time being negative; but the equilibrium of its electric contact-point for adjusting the level of mercury in the

P.S.--I find that Negretti and Zambra employ a fixed atmosphere is restored either by the earth or surrounding trough ; but I have nowhere heard of motion being given bodies. It is well known that when the machine is insulated to a contact-rod for purposes of registration. upon a glass stool, the evolution of electricity is not so abundant as when in communication with the earth. The plate, therefore, only serves the place of a medium between

MISCELLANEOUS. the rubber and the earth ; for what is abstracted from the plate is supplied by the earth. By careful deductions, the phenomena of ignition can be

Science Examinations of the Committee of made simple and easy of comprehension, and it is from the

Council Education. — The following are the laws of electric equilibrium and disturbance that the de- results of the reports of the examiners on the examination duction must be drawn. I have already exceeded the which took place throughout the United Kingdom during limits of a letter, and cannot enter further into a considera- the month of May last, comparing

the numbers of candiof ignition ; but should you favour me, as you have my from 185 to 293 ; in building construction, from 55 to 74; tion of all the facts tending to support the electric theory dates in 1864 with

those of 1865. In geometrical drawing

they have increased from 312 to 608 ; in machine drawing, former letters, I shall in a future communication resume the subject, and hope to bring some very cogent proofs of in mathematics, from 78 to 182; in theoretical mechanics, my assertions.

JEREMIAS.

from to 94 ; in applied mechanics, from 26 to 50; in Red Lion Street, E.C., October 25, 1865.

magnetism and electricity, from 269 to 291; in inorganic

chemistry, from 851 to 946; in geology, from 164 to 170 ; Suggestion of a Ner Method of Barometric Registration.

in animal physiology, from 479 to 548; in zoology, from To the Editor of the CHEMICAL News..

174 to 182; in vegetable physiology, from 121 to 229; in SIR,

Though I do not doubt that photographic registra- metallurgy, from 70 to 93 ; in navigation, from 99 to 103 ; tion of the barometer is capable of great accuracy, yet it in nautical astronomy from 70 to 82 ; in steam, from seems to me that there is still another method by which, 1 63 to 76; and in physical geography, from 70 to 121. In perhaps, as great accuracy may be obtained, without the five of the subjects there has been a slight decrease-viz., uncertain friction of a float, less liable to get out of order, in acoustics, light, and heat, from 253 to 244 ; in organic and, consequently, more useful in the hands of the public. in systematic

botany, from 70 to 33 ; and in mining, from

139;
in mineralogy,

from 28 to 19; The principle is that of an independent, vertically-moving rod, registering instantly the point at which it comes into

22 to 15. The progression during the last five years has contact with the mercury of the barometer by thus forming been as follows :-In 1861 there were 878 candidates ; in an electric circuit. As an ordinary modification, I would 1862 there were 1943 candidates ; in 1863, 2671 candisuggest that every hour the rod should be lowered through candidates. The total number of prizes given in 1865

dates ; in 1864, 3644 candidates ; and in 1865, 4593 the whole range of the barometer by clockwork. On the formation of contact, an electro-magnet, by means of an

was 1482, against 1318 in 1864. The number of medals armature, would cause a point carried along with the rod awarded in 1865 was as follows :—8 gold medals, 1 certifito be indented into the registering paper, or other material, cate instead of a gold medal, 17 silver medals, 6 certifion a revolving drum similar to those already constructed cates instead of silver medals, 22 bronze medals, and 12 for the purpose, to go for a week at a time.

certificates instead of bronze medals. The following were For more accurate purposes still the drum might be the successful candidates for the Royal Exhibitions made larger,--say five inches in diameter, and fourteen awarded after the result of this examination: For those inches long, and divided vertically into two inches for at the Royal School of Mines, London—Thomas Jones, every day. In this case the drum

would have to be moved Woolwich; Edward Collens, Bristol ; John A. Griffiths,

Manchester For those at the Government School of up on its vertical axis every time, through a division equal to the interval of registration,-one-twelfth of an inch for Science, Dublin-Frank Clowes, London ; James Craik, one hour, for instance—and the recording-point would London; John Conolly, Bandon ; W. B. Leonard,

Drogheda. remain stationary, except when acted on by the magnet. At the hour, a simultaneous motion would have to be - Fire-Damp in Coal Mines.—Mr. G. F. Ansell has given to the rod and the drum,—the first vertical and sent to a contemporary the following account of his mode descending, the other horizontal and revolving—so that of applying the law of diffusion to the indication of the one inch and a-half of the one would be equal to fifteen presence and amount of fire.damp:“Gases would appear inches circumference of the other. The electric current, to be formed of minute atoms, which have motion amongst by means of the magnet as before, would, at the instant of themselves, rapid or slow, in proportion to the density of contact, record the point at which this took place, and, the gas experimented upon. This motion of the atoms is consequently, the height of the barometer at that time. not confined to each individual gas, but the atoms of one

As I have no time for working out the idea, I have not gas pass freely through and amongst the atoms of another gone into any mere practical details of construction or gas, thus producing a perfect mixture of any two gases slight causes of variation to be allowed for, such as best which are so circumstanced as to admit of the requisite form of battery ; manner of communicating vertical motion motion. The atoms of a gas are not arrested in their to the rod; recovery of its position ; effect of duration of motion by septa of porous substances-that is, substances contact ; withdrawal of contact ; or in the second and I impervious in the ordinary acceptation, but not absolutely

to

218

Miscellaneous-Answers to Correspondents.

SCHNICAL NEWS,

Nov. 3, 1865.

80. Such substances include thin india-rubber, artificially and 10 per cent. of gas to o'io inch on the aneroid baroprepared graphite, unglazed earthenware, &c. The law nieter. The following results were obtained in the of diffusion, as educed by Mr. Thomas Graham, F.R.S., presence of experienced miners. I will, for this occasion, would appear to be as follows:-A gas diffuses into another call my indicator an aneroid barometer :- Aneroid barogas or into space in the inverse ratio to the square root of meter indicated 1:50 per cent. of fire-damp; the Davy its density. In the application of this law to the indica- lamp gave no indication. Aneroid barometer indicated tion of the presence of fire-damp I follow my original 3.00 per cent. of fire-damp; the gas could be detected by thought, and use india-rubber. "I fill a balloon of thin the Davý lamp, which gave a small pale blue flame. india-rubber (just such a balloon as that used by Aneroid barometer indicated 8.00 per cent of fire-damp; children for a plaything) with atmospheric air, and the Davy lamp exploded feebly. Aneroid barometer I place it under á lever. If now the apparatus be indicated 10'00 per cent. of fire-damp; the Davy lamp carried into a mine containing fire-damp, the fire-damp exploded fiercely. Aneroid barometer indicated 6.00 per diffuses into the balloon, in accordance with the above law, cent. of fire-damp; the Davy lamp did not explode, but quicker than the atmospheric air diffuses out from the flame elongated greatly." balloon, and the result is that there is an increase of Armenian or Diamond Cement. This article, so volume within the balloon, and this causes expansion, just much esteemed for uniting pieces of broken glass, for as would occur if so much air were forced into it. I cause repairing precious stones, and for cementing them to this increase of size to move a lever, and thereby to make watch-cases and other ornaments, is made by soaking a galvanic circuit, and so to telegraph to a distance, while isinglass in water until it becomes quite soft, and then it also rings a bell on the spot. This particular arrange- mixing it with spirit in which a little gum mastic and ment is intended to give warning of a slow accumulation ammoniacum have been dissolved. The jewellers of of fire-damp, and in practice it answers perfectly, giving Turkey, who are mostly Armenians, have a singular at each interval of an hour the increasing amount per cent method of ornamenting watch cases, &c., with diamonds of fire-damp present at that part of the mine. Supposing and other precious stones, by simply glueing or cementing the atmosphere, then, to remain without alteration the them on. The stone is set in silver or gold, and the lower balloon remains of the same size, consequently the alarum part of the metal made flat, or to correspond with the part would ring continuously for several days, but if the mine to which it is to be fixed; it is then warmed gently, and were purified, the balloon would shrink in consequence of has the glue applied, which is so very strong that the parts diffusion, and the alarum would cease. If it be desired

so cemented never separate. This glue, which will strongly to give instant notice to the men at work, or to the people unite bits of glass, and even polished steel, and may be above ground, from the working place, I use a porous applied to a variety of useful purposes, is thus made in battery cell, which, with a small column of mercury, gives Turkey :-Dissolve five oř six bits of gum mastic, each warning in a few seconds of sudden irruption of fire- the size of a large pea, in as much spirits of wine as will damp. The action of this instrument is so immediate suffice to render it liquid ; and in another vessel dissolve that, unless seen, it would appear to be incredible; it is, as much isinglass, previously a little softened in water nevertheless, trustworthy and certain. Supposing the (though none of the water must be used), in French atmosphere which has caused the indication to remain un- brandy or good rum, as will make a two-ounce phial of altered, then the instrument empties itself by effusion, very strong glue, adding two small bits of gum albanum, and the indicator returns to the original zero, and remains or ammoniacum, which must be rubbed or ground till at that point until the mine is ventilated, when the indi- they are dissolved. Then mix the whole with a sufficient cator retires from zero, thus indicating the purification of heat. Keep the glue in a phial closely stopped, and when the dangerous place. These remarks also apply to the it is used set the phial in boiling water. Some persons pocket instrument described below. The instruments have sold a composition under the name of Armenian above spoken of are intended to give warning alone; but cement in England; but this composition is badly made; if it be desired for the information of viewers, inspectors, it is much too thin, and the quantity of mastic is much owners and others to ascertain the amount per cent. too small. The following are good proportions : Isinglass, of fire-damp present in the air of mines, I vary the soaked in water and dissolved in spirit, two ounces (thick); form of my apparatus, but the most convenient form dissolve in this ten grains of very pale gum ammoniac (in is that which is assumed in the small aneroid baro- tears), by rubbing them together; then add six large tears meter for the waistcoat pocket. The mercurial baro- of gum mastic, dissolved in the least possible quantity of meter, when fitted with the necessary accompaniments, rectified spirits. Isinglass, dissolved in proof spirit, as gives very satisfactory results, as also does a column of above, three ounces ; bottoms of mastic varnish (thick but mercury, not representing a barometer. As regards the clear), one and a half ounces ; mix well. When carefully aneroid baroineter, I remove the brass back, and replace made, this cement resists moisture and dries colourless. it by a piece of porous tile-the ordinary biscuit-ware of As usually met with, it is not only of very bad quality, Wedgewood. In my first experiments I used a piece of a but sold at exorbitant prices.- Tinman's Manual and Sci. broken flower-pot, which gave as good results as could be Amer. wished for. The instrument so completed, with a few additional and purely mechanical arrangements, which I would describe were there space in this letter, may be

ANSWERS TO CORRESPONDENTS. used as an ordinary aneroid barometer, but at the time of using it, to tell the amount of fire-damp present, it is

All Editorial Communications are to be addressed to the EDITOR, necessary to close á valve by a small screw. Then having and Advertisements and Business Communications to the PUBLISHER, at read the point at which the barometer stands, and noting the Office, 1, Wine Office Court, Fleet Street, London, E.C. Private this as the zero, to remove a brass cap, which protects the porous tile ; and if there be any fire-damp present the hand travels over the face of the dial, because the diffu- We have received a note from Mr. Le Neve Foster, stating that there sion of the fire-damp into the chamber of the aneroid are no more copies of Dr. Hofmann's Exhibition Report for sale. barometer causes an increased volume, which, being com- Quero.-Should read all the lectures attentively. The term was first pelled to occupy a fixed space, causes pressure on the used by Laurent, who distinguishes two kinds of compound bodiespartly exhausted chamber within that space, and thus Aplones, or simple combinations, and Diamerones, or complex or diviscauses the hand to move over the face of the dial, indi- by the Cavendish Society.

able combinations. See “Chemical Method" by Laurent, published cating unfailingly the amount per cent. of explosive gas. Books Received. —"A Dictionary of Chemistry, &c.," by A. Watts In round numbers, i per cent. of gas is equal to or inch, B.A., F.C.S.; Part XXXII., Phenylamines to Phosphorus.

letters for the Editor must be so marked.

Nov. 10, 1866.*} Analysis of the New Phosphatic Rock Discovered in Wales.

219 SCIENTIFIC AND ANALYTICAL

In which Fe and ca are substituted one for the other in CHEMISTRY.

various proportions. As it contains no oxide of manga

nese, it may be regarded as triplite in which the man. Analysis of the New Phosphatic Rock Recently Dis- ganese is replaced entirely by lime, and the name calccovered in Wales, by Dr. T. L. PHIPSON.

triplite proposed for it. The rock is mixed mechanically

with pipeclay or aluminous schist (silicate of alumina) An extensive deposit or lode of phosphatic material has insoluble in hydrochloric acid. Some specimens contain lately been discovered in Wales, about sixteen miles a little carbonate of iron, and in No. IV. there is a good from Oswestry, in the neighbourhood of Cwmgynen, by deal of carbonate of lime. I look upon the discovery of Mr. Hope Jones. Attention was called to this deposit this new rock as likely to prove a valuable source of by Professor Voeclker, in a paper read a few weeks ago phosphoric acid in the arts, and trust that the dimensions to the British Association at Birmingham ; but, unfor- of the lode are really as great as they have been repretunately, the Professor gives no analysis of the rock sented; but I do not believe, as stated in The Reader, in his otherwise interesting paper, contenting himself October 21, p. 464, that "the phosphatic mine is readily with reference only to the percentage of phosphate of accessible and naturally drainable to a depth of about lime yielded by certain isolated specimens.

500 miles."(!) To supply this want, I publish the following analyses

4, The Cedars, Putney, London, S.W. of four different samples of the phosphatic rock, with the permission of Messrs. Griffin, Morris, and Griffin, the eminent agricultural chemists, of Wolverhampton, for whom the analyses were made.

On Boric Ethers, by MM. Hugo SCHIFF and

E. BECHI.* The rock is massive, of a very dark olive colour, inclining to black, and yields a grey powder when pul- By making different alcohols react on boric anhydride, verised. It resembles certain varieties of triplite or Ebelmen obtained, in 1846, a series of ethers, the analysis altered triphane. I have sought particularly in it for of which led to the general formulalithia and vanadic acid, of both of which I have found

B.Et,0,(Et alcoholic radical.) very minute quantities, scarcely worth alluding to in a In some researches on boric ethers we had occasion to practical point of view. In nature this phosphatic rock repeat Ebelmen’s experiments, and the results we obtained forms a wide perpendicular vein between clay-schist and were different from his. pipe-clay, and in the neighbourhood of a dark bitu- The primary action of liquid saturated alcohols, of the minous limestone, which also contains a notable propor- formula EnH2n +2+0, on boric anhydride, is expressed by tion of phosphoric acid. In the following analyses the equationNo. I. and No. II. were solid specimens, weighing several

B
Et B

B . pounds, taken from different localities ; No. III. was a

B pulverised specimen from another part of the mine, and Trialcoholic borates, whose preparation by the methods No. IV. is a mean analysis of three other distinct of Ebelmen and Rose is difficult, may be obtained readily, specimens :

and in large quantities, by causing an excess of alcoho i

II. Water 8:00

to act on boric anhydride, in a digester at about 1200. Phosphate of iron 29:40

We separate the boric ether from the unattacked alcohol

19'00 Phosphate of lime 13.00

50'00

by fractional distillation. On treating the different por.. Silicate of alumina 44'00

26.00

tions with concentrated sulphuric acid two layers are Carb, of iron, carb. of

obtained, the upper one containing the ether mixed with lime, and matters

a little alcohol and a trace of sulphuric acid. not determined 5.60

Trialcoholic borates, heated with boric anhydride, combine directly with a molecule of the latter, forming monoalcoholic borates

B Water

в 1 6.00

5'00 Phosphoric acid.

Et; } 27'00

14.60 Lime. 21'91

This transformation of trialcoholic ethers is complete.

17'35 Protoxide of iron 20.88

9:87 If, in the action of boric anhydride on alcohols, instead Silicate of alumina

38.60 of an excess of alcohol, an excess of the anhydride be Carbonic acid, &c. 2:19 Carb. of lime, &c. 14.50 used, a mixture of alcohol and mono- and trialcoholic

borates is obtained. In this case the alcohol and tri

alcoholic ether are removed by distillation, which is conIt will be seen by these analyses that the rock continued until the liquid has attained a temperature 20° or sists of phosphate of iron and phosphate of lime in very 300 above the boiling point of the trialcoholic ether. The variable proportions. The analyses lead nearly to the residue consists of monoalcoholic borate, contaminated following formula :

by boric acid ; these are separated by means of anhydrous No. I. . (2fe3P+ casi) ether, which simply dissolves the boric ether. Alcohol

will not serve for this purpose, because alcohols act enerNo. II.. ( fe'P + 3CP)

getically on monoalcoholic borates, transforming them

into trialcoholic borates. By treating monoalcoholic No. III.

( fe3P+ Ca:P) borates by alcohols homologous to those which contriNo. IV. ( fe’P+zCa'P)

buted to the formation of these borates, we prepared

mixed methyl-ethylic and ethyl-amylic boric ethers. The general formula of the rock must therefore bem Monoalcoholic borates are dense liquids, which cannot [fe

be distilled. Submitted to a high temperature, they split

* Comptes Rendrá, lxi., 697. VOL. XII. No. 310.-NOVEMBER 10, 1865.

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CHEMICAL NEWS, 220 On Some New Derivatives of Indigotine.

Nov. 10, 1865. into trialcoholic borate, and monoalcoholic triborate, ac- tion. In either instance pure sulphuric acid is added in cording to the equation

excess to the salt in a large platinum capsule, and heated

over a flame until the melted mass, when taken up on + B} = Et , } 0,+ Ei } os.

the end of a glass rod, solidifies quite firmly. The mass To effect a complete splitting up requires a tempera- is then allowed to cool; moving it over the sides of the tnre of from 250 to 2900 for the methylic and ethylic capsule will facilitate this operation. When cool it is compounds. Ebelmen, who heated only to 200°, ana- readily detached from the capsule, is then broken up lysed mixtures of monoalcoholic borates and triborates.

and put into a glass stoppered bottle. So far as my The triborates are vitreous substances, which decom- experience has yet gone, in almost every instance where pose at a very high temperature, leaving boric anhy

we have been in the habit of using bisulphate of potash dride. With alcohols they furnish trialcoholic and mixed the bisulphate of soda can be substituted.-American ethers.

Journal of Science and Arts. Unsaturated boric ethers combine neither with oxide of ethyle nor with hydriodic ethers. The latter reaction should produce boric ethylhydrines, substances

On Some New Derivatives of Indigotine, which seem to be formed by the not very energetic

by M. P. SCHUTZENBERGER." action of fluoride and chloride of boron on trialcoholic ISATINE is derived from indigotine by means of oxidaethers.

tion. Its molecule contains one atom of oxygen more The data given in this note apply only to methylic, than the latter body :ethylic, and amylic alcohols. In a future communication

6,H.NO + () = C,H,NO.
we hope to give the results of our researches on boric
ethers derived from alcohols belonging to other series.

Indigotine.
Under the influence of nascent hydrogen, obtained by

the mixture of zinc and hydrochloric acid, isatine is On the Use of Bisulphate of Soda as a Substitute for changed to isathyde, and the hydrogen becomes fixed :the Bisulphate of Potash in the Decomposition of

216gH,NO,) + H2 = € 16H1,N,,, Minerals, especially the Aluminous Minerals, by J. LAWRENCE SMITH, Professor of Chem., University

Isathyde. of Louisville.

I supposed that by submitting isatine to the action of IN referring to the more recent works on analytical

a more energetic reducer, such as a solution of hydriodic chemistry, I perceive that the bisulphate of potash is acid, at above 100°, the reduction would be more comstill used to the almost utter exclusion of bisulphate of plete and the indigotine regenerated. soda in rendering certain minerals soluble ; and it is still

This did not happen, but some reactions took place at recommended as the proper agent to fuse with aluminous from 130° to 140°, which furnished the new compounds minerals, as corundum, emery, &c.

forming the subject of this memoir. This subject occupied my attention to a considerable

I heated pure isatine at 140° in a closed vessel with extent when engaged in the preparation of two memoirs a solution of hydriodic acid of 45° Baumé. A large on the geology and mineralogy of emery presented to quantity of iodine separated itself, with the formation the French Academy of Sciences in 1850,* as well as in first of isathyde, then of a dark green amorphous mass, some investigations I am now making on the emery

insoluble in water. from Chester, Mass. In the above researches I had a

This product, washed with sulphurous acid to elimilarge number of corundums and emeries to analyse. nate all the iodine, and then in pure water, is a mixture The powdered minerals were fused with the bisulphate of three new bodies capable of being separated by of potash in the usual way, and I found no difficulty in alcohol and ether. Boiling alcohol removes a slightly decomposing the minerals; but unfortunately during the soluble white substance; then a violet-red matter almost operation a double salt of potash and alumina is formed insoluble, and which can be completely dissolved only which is almost insoluble in water or in the acids ; and by repeated exhaustion. it is only by a solution of potash that it is first decom- insoluble in all neutral solvents. The alcoholic solutions,

There remains a considerable residue of a green matter, posed and afterwards redissolved. disadvantages and delays attendant upon this method, dried precipitate yields a red body to other,

while the

be which experience soon exhibits—as the constant deposition of alum if the solution is not kept quite dilute. I white body refuses to dissolve in this menstruum. therefore experimented with the bisulphate of soda, alcohol or in concentrated acetic acid, when it is deposited

The white matter may be purified by crystallisation in knowing that the double salt of alumina and soda was in the form of microscopic needles. quite soluble, and my results were everything that could be desired ; for

while the
soda salt gives a decomposition liquid may be freed from the small quantity of the white

The red matter obtained by evaporating the etherial is very soluble in water, and in the future operations of body accompanying it by washing it in hot caustic soda the analyses there is no embarrassment from a deposit and then dissolving in crystallisable and boiling acetic of alum. The manner of employing the bisulphate of acid. On cooling it separates in the form of fine dark

red needles. soda in the analysis of emery will be referred to in a future article on the emery of Chester, Mass.

The latter body is allied to indine, which M. Laurent Preparation of the Bisalphate of Soda.—The isathyde, but is distinguished from it by its composition

obtained by the action of caustic soda on sulphuretted ordinary commercial article is not sufficiently pure for and by certain differences in its properties, use, and I prepare it from pure carbonate of soda or sulphate of soda that has been purified by recrystallisa- determined by the following analyses :

The composition of these three new derivatives was See American Journal of Arts and Sciences, vol. x., 1850, and vol. xi., 1851.

Comptes Rendus, lxi, 284.

There are many

CHEMICAL News,

Nov. 10, 1865.

The Past and Present History of Alum.

221

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IV.

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Isatino.

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III.

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1. A green matter dried at 120° :

Though all these may be composed of different elements, ist product. and product. 3rd product. yet they are arranged in the same manner, and may be

expressed by a general formula Carbon 70'11 70-27 7110 70-25 69.74

MORO, + M,0,3 RO3 + 24aq. Hydrogen. 4'36 4:51 4'41

4'37 Hence the formula :

The alums spoken of here refer to the ammonia and 632H,N_0=4(63H,NO.) +4H –30.

the potash salts. What the Romans called “alumen" was only the green sulphate of iron. But alum must have

been very early known, for Herodotus, who lived 460 Theory.

years before the Christian era, mentions Egyptian alum, Carbon

70-58

and says that the King of Egypt sent a thousand Hydrogen.

441

talents to the people of Delphos on the destruction of 2. White matter dried at 120°::-

their temple by fire; but, according to Beckmann,

the Greeks and the Romans speak of nothing but Carbon

74.57
74 76

natural alum ; and several of our most acute mineHydrogen 4:59 4'57 4'53

ralogists (mentioning Scopoli and Sage) deny the From which is deduced the formula :

existence of native alum. There must be some misCH, NO, -4(0,1,NO) + 4H-50.

tako on this point, for several alums are found Theory.

native. In the first place, there is the potash alum, Carbon

75'00

found in the Lipari Islands, Sicily, St. Michael, NorHydrogen.

4.65

way, and even in Yorkshire. The soda alum is found in 3. Matter dried at 120° :

the Neapolitan Solfatara, Island of Milo, and Mardoza. 2nd and purer

The ammonia alum at Thuringia, Bohemia. If all these alums are found now, there is no reason to suppose they

were not found then ; on the other hand, there is every Carbon . 73'31 73.34 75'04

reason to suppose they were acquainted with alum and Hydrogen 5.83

5:59

its uses ; for if we look at the skill they possessed in the Hence the formula :

art of dying, such as their Tyrian purple, etc., one can 635H29N,93=4(EgH,NO,) +8H -50.

readily believe that alum was well known to them, and Theory.

that they found it in its natural state; for eren Pliny Carbon

7441

seems to have been acquainted with it, for he says one Hydrogen

5.42

kind was white, and used for dyeing wools of a bright Both the red and the green matter fix hydrogen under colour, In Pliny's time the Egyptian alum was conthe influence of alkaline reducers, and change into white sidered the best, and, according to Beckmann, it still or yellow bodies, capable of reproducing by oxidation forms one of the exports of Egypt; "but," he says, “I the primitive compounds.

am acquainted with no author who mentions the place For these bodies I propose the following names :- where it is found or made, and as the smallest trace of 1. Green matter, isatochlorine.

alum works is not to be found amongst the ancients, the 2. Red matter, isatopurpurine.

only conclusion is that they must have found the natural 3. White matter, isatone.

alum or some other salt to which they gave that name.” They have some analogy with the products prepared

We now come to the history of our present alum. It by M. Laurent by treating sulphuretted isathyde with

was first made in the East. Beckmann says the invensoda, but are easily distinguished from them. The re

tion is later than the twelfth century ; but this cannot sults obtained by analysis are very different, and the be correct, for Geber, the Arab physician, who lived characteristics do not agree on many points.

about the eighth century, mentions it, and describes the method of making burnt alum. It seems that the

Italians procured their alum from the Levant; but when TECHNICAL CHEMISTRY.

these countries were in possession of the Turks, the

people who denominated themselves Christians did not The Past and Present History of Alum, by J. CARTER | like purchasing of the infidels, and in the course of time

Bell, Esq., F.C.S., Associate of the Royal School of they learned to make their own alum : then the chief Mines, London.

manufactory of this important salt belonged to the In reviewing the various departments of manufacturing Papal States, and the works which are near Civita chemistry we are sensibly struck by the great improve- Vecchia are considered by some to have been the first of ments made in the different branches within the last few any importance. The founder of them was John di Castro. years, and the great advantages which have accrued He acquainted Pope Pius II. of the place where the alu. from them; for in many instances the price of the che minous material might be found. These works succeedmical products has been reduced to one-half and even ing beyond their expectations, the Pope thought Castro one-fourth what it originally was, owing greatly to worthy of high honours, and a statne was erected to him the large amount of skill which is brought to bear in his own country, with this inscription—" To John di upon the subjects in question. The past and present Castro, the inventor of alum.” When the alum works history of alum offers a very good example of the of the Papal States were found to be successful, others strides which manufacturing chemistry has made. The were erected in various parts of the Continent, The discovery or invention of alum seems to be quite lost; first works which were erected in England were at Gis where it was first made or discovered is difficult borough, in Yorkshire, in the reign of Queen Elizabeth. to say, for the ancients seem to have confounded many The manufactory belonged to Sir Thomas Chaloner. He salts under the name of alum. At he present day the was obliged to engage privately some of the Pope's workword alum is applied to a number of double salts, such men, as there was nobody who understood the process as the iron, chrome, soda, potash, and ammonia alums. I in this country. But when the Pope heard of this, he

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