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186

Historical and Scientific Facts about Petroleum.

which effects the complete precipitation of the selenium at the end of a few hours. The fusion ought to be performed in an atmosphere of hydrogen; it is advisable, when the substance contains free selenious acid, to previously saturate this acid with an alkaline carbonate, so as to avoid volatilising small portions before the cyanide of potassium has had time to react upon it.

The solution obtained by treating the fused mass with water contains seleno-cyanide of potassium, together with a small quantity of selenide; it is necessary, on this account, to boil the liquid for some time before the addition of hydrochloric acid, to convert the selenide into seleno-cyanide. Without this precaution, a portion of the selenium might be disengaged in the form of seleniuretted hydrogen.

When the selenium acids are fused with alkaline carbonates, in an atmosphere of hydrogen, they are reduced to alkaline selinides; from a solution of these latter a slow current of atmospheric air entirely precipitates the selenium. This process may serve for estimating selenium, but it is less accurate than the preceding.

Sulphuretted hydrogen completely precipitates selenious acid from its solutions in the form of sulphide of selenium SeS2, from the weight of which the selenium may be determined. Selenious acid may be estimated in its aqueous solution, or, in the presence of nitric and hydrochloric acid, by simple evaporation, taking care not to exceed a temperature of 100° C., above which a portion of the acid may volatilise.

The ordinary process for the preparation of selenic acid, which consists, as is known, in precipitating this acid as a baryta salt, is far from deserving the confidence with which it is usually regarded. On the one hand, seleniate of baryta is much more soluble than the sulphate; on the other hand, it possesses, in a much greater degree than this latter salt, the property of carrying down with it considerable quantities of the soluble salts which are contained in the liquid. It is better to reduce the selenic acid into selenious acid with hydrochloric acid, and then to precipitate the selenium with sulphurous

acid.

To separate selenium from tellurium, the substance is fused with ten times its weight of cyanide of potassium in an atmosphere of hydrogen, in which the fused mass is allowed to cool. This is dissolved in abundance of water, and a current of atmospheric air passed through the solution. At the expiration of twelve hours, the deposited tellurium is separated by filtration; the selenium is estimated in the liquid in the way described above.

The separation of selenium from sulphur may be effected with cyanide of potassium, either by simple ebullition or by fusion; the first process is only applicable to the non-oxygenised compounds of selenium and sulphur. The sulphur and selenium dissolve in the form of sulphoand seleno-cyanides; the first sometimes with great difficulty, and the selenium is precipitated from the liquid with hydrochloric acid. In the second case, when the substance is fused with cyanide of potassium, the mass is dissolved in water, and the liquid boiled; selenium is precipitated with hydrochloric acid, and the sulphocyanide in the solution is transformed into sulphate, which is precipitated by a baryta salt.

To separate selenium from sulphur and tellurium, the best process consists in fusing the substance with cyanide of potassium in an atmosphere of hydrogen; to dissolve the mass in water, precipitate the tellurium with a current of air, to toil the filtered liquid; then precipitate the selenium with hydrochloric acid; and afterwards estimate the sulphur by changing it into sulphuric acid

CHEMICAL NEWS,
April 5, 1863.

by the action of chlorine, after super-saturating with potash.

Selenium cannot be separated from the metals with which it is combined when the sulphides of these metals are insoluble in the sulphide of ammonium, by making use of the solubility of selenium in this reagent. The insoluble metallic sulphide is almost always mixed with selenide. Most frequently, selenium may be separated from metals by heating the mixture in a current of chlorine; the chlorides of selenium are sufficiently volatile to render the separation generally easy. In acid solutions of the selinites of metals not precipitable by sulphuretted hydrogen, the selenium may be precipitated by this gas in the state of sulphide of selenium.

To estimate the alkalies and alkaline earths combined with selenium acids, it is sufficient to fuse them with chloride of ammonium. The alkali or alkaline earth remains in the state of chloride. One single fusion, or two at the most, are sufficient to drive off all the selenium.

When it is desired to estimate the selenic acid in an insoluble combination, particularly in seleniate of baryta, this combination is decomposed by an alkaline carbonate; the transformation into alkaline seleniate takes place even in the cold, and it is then easy to reduce the selenic into selenious acid by means of hydrochloric acid.-Poggendorff's Annalen der Physik und Chemie., cxiii. 472 and 624.

TECHNICAL CHEMISTRY.

Historical and Scientific Facts about Petroleum. WITHIN the last three years there has sprung up an important and extensive branch of industry,-the refining of petroleum, or, as it is sometimes called, mineral oil. This is already a staple article, and its use as an illuminator is becoming every day more extended. When properly manufactured it is not explosive; it affords a brilliant flame; it can be furnished at a moderate price; and, moreover, its sources of supply are abundant. The subject is one of so much general interest that we are induced to publish the following interesting article concerning this substance, which was communicated to the Scientific American by a member of the Chemical Society of Schenectady, N. Ý. :—

Petroleum is not of constant composition, but is a variable mixture of numerous liquid hydro-carbons, as benzol, naphtha, keresolene, &c., with paraffin, naphthalin, and asphaltum, solid hydro-carbons. It is of a very dark green colour, and in density varies from a thin fluid, lighter than water, to a thick viscous liquid, heavier than water. The lighter qualities yield the larger proportion of burning oil.

The evidence of the most ancient occurrence of petroleum is among the ruins of Nineveh, whose existence dates back more than 2000 years before the Christian era. In the construction of this city, an asphaltic mortar was extensively employed, the asphaltum being obtained by the evaporation of petroleum.

A later mention is found in the accounts of Babylon, whose walls were cemented with asphaltum, which was poured, in a melted state, between the blocks of stone, and an indestructible mortar thus secured. This asphaltum was procured from the fountains of Is, which were about 120 miles above Babylon, on the Euphrates. Together with saline and sulphurous water, it issued

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from a rock and was conducted into large pits. The oily matter was then skimmed off and solidified by atmospheric evaporation. These springs, from the abundance of their products, attracted the attention of Alexander, Trajan, and Julian, and even at the present time asphaltum procured from them is sold in the neighbouring village of Hits.

From time immemorial asphaltum has been found on the shores of the Dead Sea, and this is one of the most remarkable localities for it. This sea, as is well known, is of supposed volcanic origin; and is the probable site of the ancient cities of Sodom and Gomorrah. Its surface is 1300 feet below the surface of the ocean, and it has been fathomed to the depth of 2000 feet. In several places no bottom has been reached, and, owing to internal convulsions, the depth changes from time to time. The water is very dense, holding in solution 25 per cent. of solid matter, of which 7 per cent. is salt. The bituminous substance is up thrown from below, and towards the centre of the sea it is found in a liquid state, like petroleum; but it is probably solidified by evaporation, as it appears upon the shores in hard, compact masses. The explanation of this phenomenon is, that a connection between the sea and some internal volcano exists, whence this substance is ejected.

In the vicinity of the Caspian the Bakoo springs have yielded large quantities of oil, and are widely celebrated. Some of the Persian wells have furnished 1500 barrels a-day, and throughout this region this material, under the name of naphtha, is very generally burnt for its light.

At Rangoon, in Burmah, petroleum has been obtained for many years, and at this time there are over 500 wells, which annually afford 400,000 hogsheads. The oil occurs in a strata of blue clay; wells about sixty feet deep are dug, into which the petroleum oozes. This is sometimes used in its natural state, but more frequently it is first purified by distillation with steam. The raw material is also mixed with earth and used as fuel.

In Europe there are few abundant springs. On one of the Ionian Islands there is an oil fountain, which has flowed for over 2000 years; and the oracular fires of ancient Greece have been attributed to similar sources. Oil springs also occur in Bavaria, in the Grand Duchy of Modena, at Neufchatel, at Clermont and Gabien in France, and near Amiano in Italy. Petroleum procured from the last-named locality is used for lighting the city of Genoa, but elsewhere in Europe it is not employed to any extent as an illuminator.

On this side of the ocean there is an enormous quantity of this substance. Upon the Island of Trinidad, one of the West Indies, at a distance of three-fourths of a mile from the sea, is a lake of asphaltum three miles in circumference. Near the banks the asphaltum is hard and cold, but as you approach the centre the softness and the temperature increases, until finally it is liquid and boiling. From the bubbling mass proceeds a strong, sulphurous odour, which is perceptible at a distance of ten miles. Between the banks of the lake and the shore of the island is an elevated tract of land, covered with hardened asphaltum, upon which vegetation flourishes. The explanation put forward in connection with the Dead Sea is equally applicable in this case.

Upon others of the West Indies petroleum has been obtained, as well as at several places in Central and South America; but it is in the northern portion of this continent that the abundant reservoirs of this substance are located; and it seems truly wonderful that their extent and richness should not have been discovered at

an earlier period. For many years the Seneca Indians collected petroleum, and, under the name of Seneca oil, sold it as a remedy for rheumatic complaints. At numerous places in the Middle States it was found in salt borings, and was collected and burnt by the farmers, but it was not till August, 1859, that it was obtained in noticeable quantities. At this time oil was "struck" upon Oil Creek, Venango County, Pennsylvania, by sinking an Artesian well to the depth of seventy feet, and for many weeks a thousand gallons a-day were pumped from it. The news of this discovery spread far and wide, and gave rise to an "oil fever." Thousands flocked to this vicinity in the hope of making their fortunes. Before the close of 1860 there had been over a thousand wells bored, many of which were productive, but a large proportion returned nothing. Some of the adventurers have been very successful, and have made large amounts of money; but, as in all commercial "fevers," a large number of persons have been utterly impoverished by their speculations. The mere sinking a well by no means insures a bountiful flow of oil. The petroleum is stored in fissures formed by the upheaving of the earth's crust by volcanic action; and these fissures are perpendicular rather than horizontal in tendency, as is proved by the fact that at wells but a few yards apart the oil is " struck" at very different depths. The lowest parts of the fissures contain water, above which is the oil, while in the highest portion there is a quantity of gas. If, therefore, the well strikes the fissure at the lowest part, the water will be forced up by the pressure of the supernatant oil and gas. Persons ignorant of the formation sink a well at random, and perhaps strike a fissure; but, obtaining nothing but water, they abandon the spot as worthless, whereas, after removing the water by pumping, a large quantity of oil might be obtained.

In some localities in Ohio, as is the case in Burmab, the ground is saturated with the oil, and wells several feet in diameter are dug, into which the oil oozes. Porous limestone, containing petroleum, is found in somo sections of the West, and has been subjected to distillation with profitable results.

In regard to the origin of petroleum, scientific authorities differ; but the theory most generally favoured is, that it is the product of the slow distillation, at low temperatures, of organic matter in the interior of the earth, the vapours being condensed in the previouslymentioned fissures and the surrounding soil. The Lake of Trinidad, and the bituminous matter of the Dead Sea, may also be referred to a similar source. But for how many centuries must this operation have been going on to have effected such enormous results?

Of the many uses to which petroleum and its derivatives are applied, that of illumination is the most important; and the process of refining is exceedingly simple. The crude material is put into a large iron retort, connected with a coil of iron pipes, surrounded by cold water, called the condenser. Heat is applied to the retort, and from the open extremity of the condenser a light-coloured liquid, of a strong odour, soon flows, This is naphtha, and is very volatile and very explosive. Some refiners mix it with the burning oil, and numerous accidents have resulted from such mercenary indiscretion. It is usually run into a separate tank. After the naphtha has passed over, the oil used for illumination distils off. Steam is now forced into the retort and the heavy lubricating oil driven over. There now remains a black, oily, tarry matter, sometimes used to grease heavy machinery, and a black coke, employed a fuel. There are, therefore, five substances separated

188

On the Corrosion of Zinc-covered Water-pipes.

this operation, but only the first three are of any economic importance.

The naphtha is used as a substitute for turpentine in paints, or, by repeated distillations, the benzole is separated from it, and employed to remove spots from fabrics. This, however, is rather a drug in the hands of the refiner.

The burning oil, as it comes from the retort, is of a yellow colour, and, in order to remove this, it is placed in a large, lead-lined cistern, and agitated with about ten per cent. of sulphuric acid. After the acid and impurities have subsided, the oil is drawn off into another tank, and agitated with four per cent. of soda lye. This last operation is to remove any acid remaining with the oil, and also to extract the residue of the colouring matter. In fact, it is sometimes employed alone, and a very good oil obtained. The oil is now agitated with water to remove the soda lye, and is then ready for consumption. The colourless oil is by no means the most economical, but, on the contrary, more light is obtained from the yellow article.

The heavy oil is cooled down to 30° F., when the paraffin crystallises out, and is separated from the oil by pressing. It is further purified by another pressing and by alternate agitation, in a melted state, with sulphuric acid and soda lye. It is then moulded into candles. It is a curious fact, that the composition of paraffin and good coal gas is exactly the same.

In Egypt, a substance derived from petroleum was used in embalming bodies; and in Persia and the neighbouring countries, asphaltum is used to cover the roofs of the houses and to coat the boats. In France, asphaltic pavements have been successful in several cities, and for the protection of stone no material is better adapted. Mixed with grease, the Trinidad asphaltum is applied to the sides of vessels to prevent the boring of the teredo, and with quicklime it affords an excellent disinfectant. Among the products of the distillation of petroleum are naphthalin and keresolene. The former is the substance from which is obtained aniline,-the base of the beautiful colours, Mauve, Magenta, and Solferino. The latter has been proposed as a substitute for chloroform and ether. Many other substances have been separated, but as yet none of them have been applied.

On the Corrosion of Zinc-covered or "Galvanized"
Pipes when used for Conducting Water, by A. A.
HAYES, M.D.

IRON pipes covered with a firmly-adhering surface of
zine more or less pure, have been used as conduit pipes,
under the received supposition that the zinc, by its
polarising action from contact, will preserve the iron
from corrosion, in the act of itself suffering oxidation.
As the oxide of zinc, formed under some circumstances,
adheres to the metal and encrusts it with a body not
soluble in water, it has been assumed that water, passing
through such pipes, would not become contaminated by
either iron or zinc oxide.

Some months since, I analysed some well-water, which had produced a white deposit in the culinary vessels in which it had been boiled, and was itself turbid. The deposit proved to be oxides of zinc and iron with organic matter, and the water held suspended and dissolved organic salts of both these metals. On learning the fact that the pipes had not been long in use, a request was made that suitable precautions should be taken to avoid

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{CHEMICAL NEWS,

April 5, 1862.

using the water in preparing food; and by ensuring a large flow of water through the pipes continued for several weeks, the possible formation of a protecting surface was expected. But after long exposure in this way to much water drawn from the well, analyses of the water in the pipe and that in the well did not indicate any diminished action on both the metals. The zinc exposed to this water not only dissolved in it, but lost its usually observed power of protecting the less oxidisable metal in contact with it, and the quantity of saits formed from both metals was so large as to render it unfit for general domestic use.

Some weeks later, I received a sample of water from a more distant town, the purity of which was suspected, and this was found to contain organic salts of zinc and iron also, although colourless and transparent. In this case the galvanised pipe had been longer exposed, and symptoms of anomalous disease in the family consuming the water, led to the chemical trials. The acid present in both salts appeared to be the crenic, and, in one case, traces of ammonia were found, constituting a compound salt. When the water was boiled, especially in metallic vessels, a white deposit of oxides of zinc and iron, with altered organic matter, appeared, but long-continued ebullition was required to ensure complete decomposition

of the salts.

The observed loss of protection in this exposure was

deemed a point of much interest, for I had repeatedly
surfaces, and have recommended this resort in numerous
examined iron boilers protected from corrosion by zinc
stances, where the protection seemed to be nearly
cases within the last thirty years, under varied circum-
complete.

Dana, of Lowell, he informed me that zinc surfaces
Mentioning these facts to my friend, Dr. Samuel L.
failed to protect iron surfaces exposed to the flowing
water of the Merrimac River, and showed me the result
of such trials; the iron being much corroded both near
by, and remote from the protecting metal.
As the kinds of well-water which acted on the zinc
and iron in these cases are quite common in every part
of New England, it seems doubtful, in a sanitary point
of view, if such pipes are proper for conducting water
generally; for, even when care is exercised, the metals
dissolved in the water will surely be found in the food
partaken of by families thus supplied.

I am aware that many persons consider both zinc and iron compounds, when taken into the system, as not actively poisonous, if even harmful; compounds of iron, especially, being found in the system. The chemical fact of the most importance in this connection is, that the compounds of iron naturally found in the system are derived from compounds of iron existing in the food by the simplest transformation, and that other forms of combination will not supply these, and are active extraneous bodies, which leave their marks on the stomach tissues.

In illustration of the activity of an iron salt when the dose is very minute, the effects of chalybeate waters may be instanced, and there are few medical men who have not witnessed the most surprising changes in the system induced by these, even when the ordinary preparations of iron have failed in their action. Now, in most of the ferruginous waters, it is the crenate of the protoxide of iron which occurs the same salt which the galvanised pipes produce,-while the zinc is not found as the wellknown oxide, but in the state of an active salt corresponding to the iron compound, and has no claim to consideration as a body forming healthy secretions.- Boston Medical and Surgical Journal.

PHARMACY, TOXICOLOGY, &c.

On the Behaviour of Essential Oils to Iodine and Bromine, by JOHN M. MAISCH. (Continued from page 149.)

Oleum Mentha piperita Germ.-Rectified, nearly colourless, thin.

Iodine, aided by stirring, dissolves, without any brisk reaction, to a reddish brown liquid of the consistence of honey; the residue of heavier oils is thicker, but still fluid; oils distilled from old herbs evolve a few vapours. Z.

It has a quiet and slow reaction, and dissolves to a brownish liquid, with which the black iodine sediment mixes to a syrupy liquid.

Ether sol. iodine is spreading, miscible to an iodine coloured liquid, which changes to a thick yellowish, blackish brown; after twelve hours it has a deep greenish brown colour, and the consistency of butter. Ether sol, bromine.-The mixture has a beautiful rose colour, which gradually darkens, but retains in thin layers a pinky shade.

Oleum Mentha viridis.-Yellowish, red, old, rather thick.

Iodine dissolves slowly to an evenly thick iodine coloured liquid.

Ether sol. iodine shows little spreading, and mixes to an iodine coloured solution; in six hours it is a thick, chesnut brown liquid, and after twelve hours more it has a butyraceous consistence.

Ether sol. bromine.-A few white fumes are evolved; the yellowish red solution passes through various shades to a deep yellowish brown; the sediment is of a lighter colour. (Separation of water?)

Oleum Monardæ. -The crude oil, light brown, one year old.

Iodine dissolves quietly; during the first few moments a nearly vermilion red colour is produced, which soon darkens to a brownish red; the nearly black sediment is of a pitchy consistence.

Ether sol. iodine is miscible to a clear iodine-coloured

solution.

Ether sol. bromine mixes to a brownish violet colour, which subsequently deepens to a dark purplish brown. Oleum Myristica.-Colourless, thin. Iodine.-Violent reaction with explosion, and with white and some purple vapours; the residue consists of a light blackish green solution, with a deep greenish brown sediment, which are miscible to a transparent liquid, assuming a more yellowish shade, and is subsequently light greenish yellow.

Ether sol. iodine.-The mixture has instantly a turbid yolk-yellow colour, and is afterwards transparent and colourless, regains a yellowish brown tint, and is rendered colourless again.

Ether sol. bromine.-At first colourless; the heavier part assumes a light brownish milky appearance, the brown shade afterwards disappears; the upper stratum remains transparent, with scarcely a brownish tint.

Oleum Patchouly.

Of this oil, which is extensively used in perfumery, I had three different kinds at my disposal, of which at least two were of lots imported at different times; they were all of a brown colour, and about the consistency of olive-oil; one approached more the consistence of castoroil; their very characteristic behaviour was alike.

Iodine dissolves with radiating motion, without vapours, to an iodine-coloured solution, which changes to brown black, afterwards to bluish green black; the liquid is not thickened.

Ether sol. iodine dissolves, without spreading, to a homogeneous dark green liquid, which is nearly black in appearance; after twelve hours no change had taken place, except the formation of a black precipitate. white vapours, to a solution of a splendid deep violet colour; it deepens in its shade so as to appear almost black; upon the sides of the vessel, when some spreading had taken place, indigo blue stripes, and vermilion red spots were observed, the colour of which darkened to greenish black and yellowish green black; the oil was not thickened; the sediment had the colour of burned

Ether sol. bromine mixes with the evolution of a few

umber.

No difference from the reaction of the pure oil could Oleum Patchouly two parts, oleum Limonis one part. be observed in the behaviour of this mixture to the ethereal bromine solution, except that upon the sides of the dish a brownish green margin was visible.

Oleum Rhodii ligni.-Yellowish, slightly viscid. Iodine.-Scarcely any action; but, on stirring, the oil assumed a greenish hue, and gradually dissolves iodine, forming a deep greenish brown liquid.

Ether sol. iodine.-Miscible with very little spreading, and scarcely any undissolved particles; the liquid has a peculiar yellowish brown iodine colour; gradually it separates, the upper stratum being of a greenish yellow, the lower one of a greenish brown. In six hours it is again of a uniform thin consistence, and of a greenish yellow brown colour.

Ether sol. bromine at first collects on one side of the

dish, gradually sinks below the oil, and the reaction now shows a pure yolk colour; then brownish stripes appear on the surface of the lower stratum, which increase in size until the colour is entirely changed to umber brown; the supernatant liquid shows scarcely a brownish tint; after stirring the two together, they separate again.

Immediately after the above reactions, the odour approaches nearer the perfume of roses than in the original oil.

Oleum Rosmarini.—Yellowish, almost colourless, thin.

Iodine.-Radiating motion of the iodine solution, with few red vapours, and some heat; the yellow brown residue, of the consistence of a soft extract, has its odour unaltered. Another sample showed a curdy precipitate in a yellowish brown liquid, which could not be mixed to a uniform mass. Z.

With a brisk radiating motion, and the evolution of white vapours, a solution is obtained of a brown colour, tinged with yellowish green; the dark greenish brown sediment is miscible by agitation.

Ether sol, iodine.-Two strata are formed, the lower one of which has a deep iodine colour, while the upper one is much lighter coloured.

Ether sol. bromine yields a colourless mixture, which separates into a colourless, clear upper stratum, while the heavier oil is milky white; the latter then changes to a light brown, and the former is rendered white and cloudy.

Oleum Ruta.-Yellow, with a bright brownish tint scarcely thickish.

Iodine. The oil prepared by Zeller dissolved the iodine slowly without heat, vapours, or motion, to a yellow brown liquid; with the commercial oil, little

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heat, a few vapours, and some radiating movement were observed. Z.

It dissolves with some radiating motion to a yellowish iodine coloured liquid.

Ether sol. iodine.-On dropping it into the oil, some spreading occurs, the iodine sinks to the bottom, the supernatant liquid is yellow; without stirring, the two combine to a homogeneous solution of iodine colour. Ether sol. bromine.-The mixture is at first slightly cloudy, but has a pale brownish yellow shade afterwards.

Oleum Sassafras.

I have examined two oils, one anhydrous and colourless, the other one being yellowish brown, and containing water, both perfectly transparent; they were the upper and lowest stratum of an oil saturated with water, which had stood undisturbed for about a month. (See Proceedings of Amer. Pharm. Assoc., 1858, p. 355.), Iodine dissolves, without heat or vapours, to a clear, uniform, yellow-brown liquid, without thickening appreciably. Z.

It dissolves entirely without vapours or motion; the solution has an iodine colour; the odour is unaltered. The yellow oil has the same behaviour, only effects the solution slower.

Ether sol. iodine mixes, with spreading, to an iodine coloured liquid, which after five hours is limpid and of a rose colour.

The yellow oil yields a darker solution, spreads more than the former, and after five hours had changed to a somewhat thicker, blackish brown oil.

Bromine. Hissing, some heat, and white vapours; the oil is milky, and around the bromine shows a yellow and green colour; odour somewhat resinous. The dark oil was not tested.

Ether sol. bromine mixes easily, with some heat and vapours; the mixture is milky, with yellowish spots at

the bottom.

The dark oil shows the same reaction; the liquid is milky, gradually turns green; the sediment yellowish, then green, and getting darker; the margin is now blue, then violet, and subsequently rose colour.

(To be continued.)

PROCEEDINGS OF SOCIETIES.

SOCIETY OF ARTS.

Wednesday, February 5.

Dr. A. W. MILLER, F. R. S., Professor of Chemistry at King's College, in the Chair.

Continued from page 175.)

"Mr. Charles Lauth also published on December 24, 1860, an ingenious method of obtaining purple aniline, which I shall describe when treating of blue colours obtained from aniline.

"Red Dyes obtained from Aniline, called fuchsine, azaléine, roseine, &c.-The production of the fine colour, which bears the popular name of Magenta, was first observed by Mr. Natanson in 1856, and more especially by Dr. Hofmann when preparing cyantriphenyl-diamine, by the action of bichloride of carbon on aniline. But it was M. Verguin who first brought it forward to the trade as a dyeing agent, and his mode of preparation, which was patented in April, 1859, by Messrs. Renard and Franc, of Lyons, is the following :-Into a glazed iron pan are introduced 100 parts of aniline and 60 parts of anhydrous bichloride of tin, and the whole is heated

CHEMICAL NEWS, April 5, 1862.

for 15 or 20 minutes, at a temperature of about 392°. The dark red liquor thus produced is left to cool, when it becomes thick and glutinous; it is then mixed with boiling water and filtered; to the filtrate is added chloride of sodium, which determines the precipitation of fuchsine, as it is insoluble in saline solutions. Magenta was afterwards prepared by C. Greville Williams, with permanganate of potash, and by Dr. D. Price, with binoxide of lead; nitric acid, and nitrate of mercury were also successfully employed. These different methods of preparing Magenta were followed by several other patents, purporting to obtain the same results, and amongst them I may cite that taken on December 10, 1859, by Mr. Rudolph Heilman, in which the employment of arsenic acid is mentioned, and one also for the employDr. H. Medlock. ment of the same agent on the 18th of January, 1860, by As it is probable that this agent is the best suited for producing Magenta, commercially, I will give a sketch of the process. Dr. Medlock heats two parts of aniline with one of arsenic acid to about 250°, and when the red colour is produced it is mixed with boiling water and allowed to cool. The red colour is thrown down by saline matter, washed, and dissolved in methylated alcohol, or the mass is digested in hydrochloric acid diluted with water, and the clear fluid solution is saturated with an excess of soda which precipitates the colour, while the arsenious acid is held in solution by the alkali. Magenta is a rather powerful organic base which is sparingly soluble in water, but its solubility is increased by the presence of an acid. It leaves a brittle mass, having a beautiful golden green metallic reflection when its alcoholic solution is left to spontaneous evaporation, and this is not peculiar to Magenta, as the whole of the coal tar colours, when in a high state of purity, present the same appearance. Purple aniline differs from the red, not only in its composition, which is as follows:

Purple.

C36 H17 N3 O2

Red.

4

C36 H20 N1 O1 but also because the fuchsine dissolves in ammonia and in sulphuric acid with a yellow colour, and is discoloured by sulphurous acid, whilst the purple is unaffected by those reagents. Silk or wool is dyed with fuchsine by simply adding some of the colour to a slightly acidulated bath. The dyeing colour of this material is so great that 10 grains will dye 2 square yards of silk.

"Of late years many attempts have been made to fix another colour obtained from coal tar, called rosalic acid (C12 HO3), but up to the present time I believe all attempts have failed, with the exception of rosalate of magnesia, which was employed for some time in calico printing.

"Blue Colouring Matters from Coal Tar.-I have already drawn your attention to the blue colouring matter patented by Mr. Girard, and carried out practically by Messrs. Renard and Franc, of Lyons. Mr. Lauth also has observed that if an alcoholic solution of red aniline, and especially azaléine, is heated with a reducing agent, such as protochloride of tin, or still better with aldehyde or hydruret of benzoïle, a blue colour is produced even at ordinary temperatures. This blue colour is soluble in water, alcohol, and acetic acid, but does not resist the action of mineral acids, alkalies, or light.

"Mr. Willm has recently published an interesting paper on this aniline blue, which not only shows how aldehyde acts, but exhibits the composition of the blue itself.

=

Azaléine

Aldehyde

Water.

2 (C36 H20 N4 O1) + 5 С ̧ Н ̧ O ̧ + 8 HO Blue or Oxyphenylanilide Acetate of Ammonia. = 3 (C1⁄2 H11 NO3) + 5 C ̧ H3 (N H1) 0. "Therefore the triamine azaléine has been transformed into a monamine blue, by a new chemical reaction, for aldehyde not only acts as a reducing agent, but converts a part of the nitrogen into ammonia.

"Bleu de Paris.- Recently, Messrs. Persoz de Luynes, and

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