SCIENTIFIC

AND ANALYTICAL CHEMISTRY.

Further Remarks on the Preparation of the Ethyl Bases by means of Nitrate of Ethyl, and their Separation, by M. CAREY LEA, Philadelphia.

FREQUENT repetition of the process which I have previously described, confirms me in my opinion of its advantages. Nitrate of ethyl is obtained easily and abundantly. From 480 grammes of alcohol of 40° Baumé, I have obtained 231 of nitrate of ethyl, and even a still larger proportion. It is essential in operating upon quantities of half a litre or over, of the mixture of alcohol and nitric acid, to first raise the alcohol to a boiling heat and dissolve the urea in it, and then add the nitric acid, otherwise it may attack the

alcohol while the urea remains undissolved at the bottom of the vessel, and thus cause the whole process to fail. I have prepared six or seven pounds of nitrate of ethyl in this way with very little trouble.

In acting upon the nitrate of ethyl with ammonia, it is necessary that the pressure tubes should be extremely strong, and should never be more than one-half full.

Saline baths are not to be used.

Triethylamine appears to be only an occasional pro

duct of this reaction.

In employing the process which I have recommended for removing the ammonia, viz., converting the mixed bases into sulphates and exhausting with absolute alcohol, it does not answer well to add sulphuric acid to the crude products obtained from the pressure tubes, because it is impossible to know the exact quantity of sulphuric acid required to expel the nitric acid. If too little be employed, some nitrate of ammonia might remain and dissolve in the alcohol. If too much, bisulphate of ammonia may be formed, and this likewise would dissolve to some extent in the alcohol and contaminate the product. It is therefore necessary to distil the crude products with caustic alkali, neutralise exactly with SO, and then evaporate to dryness and exhaust with alcohol, as described in the paper here referred to. In employing picric acid to separate the ethyl bases, each picrate, after having been purified by recrystallisations, is to be treated with chlorhydric acid. The greater part of the picric acid separates, and a further portion by evaporating the liquid. Some, however, remains; and it is important to get rid of it, because picric acid, when distilled with aqueous caustic alkali, evolves ammonia, which would thus contaminate the ethyl base. This is effected as follows: After the chlorhydrate of the ethyl base has been evaporated as far as possible without crystallisation, a very little carbonate of potash is to be added, and the solution stirred at intervals. Almost every trace of picric acid is thus precipitated. In the final distillation of the chlorhydrate with

Oleum Serpylli.-Pale yellow, nearly colourless, thin. Iodine produces radiating motion with the oil from the fresh herb, which evolves few yellowish red vapours; with oil from the dried herb, the reaction was stronger, more heat and more vapours were given out; the residue has an extractive consistence. Z.

A brisk radiating reaction takes place, the solution has an iodine colour, and is miscible with a dark sediment. Ether sol. bromine.-Some spreading, the solution is yellowish red; after six hours, brownish yellow.

Ether sol. iodine.-White vapours; each drop is immediately decolorised; the oil gradually turns to a greenish

colour.

Oleum Spica.-Old greenish yellow, oily consistence.

oil of lavender; it evolves less fumes, but more heat; Iodine explodes with less force with this oil than with the yellowish brown residue is of soft extractive consistence, and has a modified balsamic odour. Oil of second quality evolved few red fumes only by the influence of a larger proportion of iodine; less heat, no vapours, more fluid residue. Z.

It dissolves slowly by stirring, and has a tar-like sediment.

Ether sol. bromine mixes to a transparent, reddish yellow liquid.

Oleum Tanaceti.-Pale yellow, thin. Iodine dissolves quietly without heat and with little radiating motion; the residue is liquid, of the consistency of a thin syrup and unaltered odour. Z.

On the introduction of the iodine, a brisk reaction takes place, with many grey and a few violet_vapours; the solution is deep yellowish green, afterwards purely green, and is miscible with the remaining black sedi

ment.

Ether sol. iodine.-The upper portion is of a yellow iodine colour; the lower stratum is thick, brown; miscible to a yellowish red iodine-coloured transparent liquid.

Ether sol. bromine.-The mixture is at first colourless, separates into a thin milky liquid and a heavier light brown oil.

I was not aware of the considerable variation of the result of the above experiment with iodine, from the results of Zeller, Liebig, and Tuchen, until I was collecting my notes for this essay. I knew that the oil employed by me was several years old, but as it had preserved its physical qualities, I was satisfied about its purity; particularly the odour was purely that of tansy, without any admixture. Zeller states, alcohol of 85 dissolves the oil in all proportions; that which I experimented with, required three parts of alcohol for complete solution at 70° F. The reactions, as stated by me, seem to coincide with an adulteration with turpentine; but, judging from all physical properties, I am still of the opinion that the oil is pure, somewhat modified by age. Could age produce such a difference, or is this the effect of our climate? I shall have to inquire into this matter.

thickish.

Oleum Valerianæ.-Light brownish yellow, rather Iodine dissolves with little heat to a dark yellow

brown mass of extractive consistence; some genuine oils evolve a few greyish yellow vapours. Z.

The solution is effected with very slight radiating movement; the liquid part is yellowish brown, the sediment nearly black; without stirring, the whole assumes gradually a pitchy consistence.

Ether sol. iodine is miscible with an iodine colour to two not well defined strata, which, by agitation, are easily miscible.

Ether sol. bromine.-Each drop produces a deep purplish black colouration; a separation into two strata takes place, the lighter one, being in the smallest quantity, assumes such a deep violet colour as to appear black; the heavier one is of a greenish black colour; around the margin of the whole liquid are reddish and bluish spots and streaks.

III.—THE SULPHURETTED AND NITROGENATED OILS. Oleum Amygdala amaræ.-One colourless, another one brownish, pale.

test-liquids, &c. I have also given the mode of Zeller's procedure with iodine, which, as far as quantity is concerned, I have carefully followed. But one great difference in the mode of our observation is, that Zeller applies a moderate heat to the thicker oil, so as to render the fluidity of all about alike, while I have taken the opposite course, by making the experiments at as nearly as possible alike temperatures. Necessarily, a difference in the degree of the reaction of iodine must arise, and by comparing the energy of the reaction of the more viscid oils, such a difference, slight and unimportant though it may be, will be noticed, the most vigorous reaction being obtained by Zeller's method.

In the subsequent course of observing the changes, I have also followed another suggestion. Zeller, after the first reaction is over, stirs, by means of a glass rod, the undissolved iodine together with the liquid. It appeared to me more important, to notice not only the reaction of the iodine on the oil, but likewise that of the oil upon

the iodine. This is the reason that, in my observations, we often meet with expressions like "dark extract," "deep brown pitchy sediment," &c.; this sediment is generally occasioned by the undissolved iodine, which, on the point of its contact with the oil, is often changed to a resinous mass which envelopes the unused iodine, preventing its farther action on other particles of the oil. This is another cause of the difference between our observations; but my course appeared to me to be the better one, as, though the energy of the reaction may be mediate changes, while the final results will, in most partly lost, more time is gained for observing the intercases, be nearly alike, although from the greater amount of heat, necessarily developed by agitating the two reacting substances, a farther going change might reasonably be expected.

The Poisonous Effects of Carbonic Oxide, by H. LETHEBY, M.B., M.A., Ph.D., &c., Professor of Chemistry and Toxicology in the Medical College of the London Hospital.

observation.

Ether sol, iodine mixes quietly and readily to a deep iodine-coloured liquid; the whole of the liquid is spread ing out, working up the sides of the vessel a thick black margin; in six hours the whole has run together again, and forms a dark brown coloured mass of the consistence of honey.

Ether sol, bromine dissolves without reaction; after favouring the evaporation of the ether by a current of air, a separation takes place into a deeper and a lighter red-coloured liquid, with slight cloudiness on dividing line of both.

the

Oleum Sinapis.-Light yellow. Iodine dissolves quietly without external reaction to a brownish yellow liquid, which is hardly thickened. Z. It forms easily a perfect solution, with scarcely any radiating motion; the colour is a red iodine.

Ether sol. iodine.-Miscible without any peculiar reaction to a reddish yellow iodine-coloured liquid. Ether sol. bromine.-Miscible, colourless, subsequently slightly milk white.

Remarks on the Course of Observation.-Above I have described the manner in which the experiments were performed, by giving directions for preparing my

in all probability the effects of the gas were entirely hand, accidents have somewhat recently occurred where been unjustly attributed to it. Some of this confusion overlooked; and on the other, fatal consequences have is due to the circumstance that our standard works on poisons and medical jurisprudence have either omitted the subject entirely, or have discussed it in very meagre language. The recent catastrophe at the Hartley colliery, and the remarks which have been published redeath of the men, have created an opportunity for a respecting the supposed influence of the gas in causing the examination of this question.

Carbonic oxide was discovered by Priestley long before the close of the last century; and in 1802, Clement and Desormes, at the instance of Guyton Morveau, undertook a careful examination of its properties. They not only proved its chemical nature, but they also ascertained that it was a poisonous gas. Birds put into it dropped dead before they could be taken out; and when the experimenters themselves attempted to breathe it they were attacked with giddiness and faintness. This experiment was repeated by Sir Humphrey Davy in it, mixed with about one-fourth of common air, the effect 1810, who says that when he took three inspirations of was a temporary loss of sensation, which was succeeded by giddiness, sickness, acute pains in different parts of

CHEMICAL NEWS, April 19, 1862.

About the same time, the researches of Nysten demonstrated that the gas was capable of producing great disturbance of the system when injected into the veins; and although he concluded that the effects were of a mechanical nature, yet the accounts which he has given prove that the gas is a dangerous poison.

Later still, in 1814, the two assistants of Mr. Higgins, of Dublin, made experiments with it upon themselves, and in one case, that of Mr. Wilter, with almost a fatal result. Having exhausted the lungs of air, he inhaled the pure gas three or four times, and was suddenly deprived of sense and volition; he fell upon the floor, and continued in a state of perfect insensibility, resembling apoplexy, and with a pulse nearly extinct. Various restorative means were employed, but without success, until they resorted to the use of oxygen, which was forced into his lungs, and then his life was restored; but he was affected with convulsive agitation of the body for the rest of the day. He suffered also from violent headache, stupor, and a quick, irregular pulse. Even after mental recovery he suffered from giddiness, blind- | ness, nausea, alternate heats and chills, and irresistible sleep. The other gentleman, after inhaling the gas two or three times, was seized with giddiness, tremor, and incipient insensibility. These effects were followed by languor, weakness, and headache of some hours' duration. Since those experiments were made, others of a more extended character were instituted by Tourdes and by Leblanc. Tourdes found that rabbits were killed in seven minutes when they were put into a mixture of one part of the gas with seven of atmospheric air. A fifteenth part of the gas in common air killed them in twentythree minutes; and a thirtieth part in thirty-seven minutes. Leblanc's experiments were made in conjunction with Dumas, and he ascertained that one per cent. of the gas in atmospheric air would kill a small dog in a minute and a-half, and that birds were killed immediately in a mixture containing five per cent. of it.

Very recently I have myself ascertained that air containing only o5 per cent. of the gas will kill small birds in about three minutes; and that a mixture containing one per cent. of the gas will kill in about half this time. An atmosphere having two per cent. of the gas will render a guinea-pig insensible in two minutes; and in all these cases the effects are the same. The animals show no sign of pain; they fall insensible, and either die at once with a slight flutter,-hardly amounting to convulsion, or they gradually sleep away as if in profound coma. The post-mortem appearances are not very striking: the blood is a little redder than usual, the auricles are somewhat gorged with blood, and the brain is a little congested. In birds there is nearly always effusion of blood in the brain, and it may be seen through the transparent calvaria by merely stripping off the scalp after death.

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in this country and on the Continent. Sellique, in 1840, obtained permission to use the gas in the towns of Dijon, Strasburg, Antwerp, and two of the faubourgs of Paris and Lyons. At Strasburg an accident occurred which put a stop to its use. The gas escaped from the pipes into a baker's shop, and was fatal to several persons; and not long after an aeronaut, named Delcourt, incautiously used the gas for inflating his balloon. He' was made insensible in the car, and those who approached the balloon to give him assistance fainted and fell likewise. The use of the gas has, therefore, been interdicted on the Continent.

Another source of danger from it is in the combustion of carbon. It is found in the neighbourhood of brickkilns and furnaces. The gases discharged from the latter contain it in large proportion. Iron furnaces produce it to the extent of from twenty-five to thirtytwo per cent., and copper furnaces from thirteen to nineteen per cent. In the year 1846, M. Adrien Chenol was anxious to ascertain the properties of the gases yielded by his process of smelting zinc ores with carbon; and, not having a suitable instrument for collecting the gases, he attempted to draw them out of the furnace by means of a pipette. Some of the gas was thus inhaled, and he fell immediately, as if he had been stunned; the eyes were turned back in the orbits, the skin was discoloured, the veins were swollen, and presented a black tint under the skin; there were violent pains in the chest, and the brain felt powerfully oppressed. After removal to the open air, and the application of restoratives, sensibility gradually returned, but the internal pains were still severe, and there was a feeling of suffocation. For several days he felt depressed and languid; the digestion was bad; sleep was obstinate and heavy, and it was frequently disturbed by cramps in the knees and toes. Even for months afterwards there was a morbidly excited state of the nervous system.

In a more diluted condition the gas is still able to exert an injurious action, and it is very probable that the singular catastrophe which happened at Clayton Moor, near Whitehaven, in the summer of 1857, was caused by the diffusion into the air of carbonic oxide from the neighbouring iron furnaces. There is a row of cottages near to these furnaces where, in the month of June, 1857, a number of persons were suddenly seized with insensibility, which soon passed, in some cases, into coma and death. About thirty persons were thus attacked, and six of them died. The effects were attributed at the time to the escape of sulphuretted hydrogen from the slag on which the cottages were built; but it is more probable they were caused by the oxide of carbon from the furnaces.

Lastly, it is worthy of remark that very recently Boussingault has noticed that the leaves of aquatic plants give off carbonic oxide and marsh gas when under the influence of solar light; and he asks whether this gas so produced may not be concerned in the unhealthiness of marsh districts.

A more complete acquaintance with the effects of this poison is a great desideratum, although enough is known to indicate its general mode of action, and to furnish evidence for its discovery.--Lancet.

Detection of Glucose Mixed with Cane Sugar.

The

PHYSICAL SCIENCE.

On Spectrum Analysis, by W. A. MILLER, M.D., LL.D., V.P.R.S., Professor of Chemistry, King's College, London.

(Continued from page 203.)

4. Spectra of Coloured Flames.—The first person who seems to have examined a coloured flame by means of the prism was Sir David Brewster, who proposed, as a source of achromatic light, the flame of diluted alcohol, which he found gave a fine homogeneous yellow, with faint traces of green and blue. In the same volume of the Edinburgh Phil. Trans., 1822, at p, 455, Sir J. Herschel describes briefly the spectra of muriate of strontia, muriate of lime, chloride and nitrate of copper, and boracic acid. The same observer, in the article, "Light," Encycl. Metrop., 1827, p. 438, says :-" Salts of soda give a copious and purely homogeneous yellow, of potash a beautiful pale violet." And he there gives a general statement of the results with the salts of lime, strontia, lithia, baryta, copper, and iron. He further continues:-"Of all salts the muriates succeed best, from their volatility. The same colours are exhibited also when any of the salts in question are put in powder into the wick of a spirit-lamp. If, however, salt be used, Mr. Talbot has shown that the light is an absolutely homogeneous yellow. The colours thus communicated by the different bases to flame afford, in many cases, a ready and neat way of detecting extremely minute quantities of them. The pure earths, when violently heated, as has recently been practised by Lieutenant Drummond, by directing on small spheres of them the flames of several spirit-lamps, urged by oxygen gas, yield from their surfaces lights of extraordinary splendour, which, when examined by prismatic analysis, are found to possess the peculiar definite rays in excess which characterise the tints of flames coloured by them, so that there can be no doubt that these tints arise from the molecules of the colouring matter reduced to vapour, and held in a state of violent ignition."

The analysis of the spectra of artificial lights was resumed by Mr. Fox Talbot, who published a paper in 1826, in vol. v. of "Brewster's Journal of Science." He there describes a method of obtaining a yellow monochromatic light by the use of an ordinary spiritlamp, with a cotton wick fed with dilute alcohol holding common salt in solution. He found the same effect, whether muriate, sulphate, or carbonate of soda were employed.

Nitrate, sulphate, chlorate, and carbonate of potash, agreed in giving a bluish-white tinge to the flame. By burning a mixture of nitre and sulphur, he observed a red ray, of low but definite refrangibility, which he regarded as characteristic of the salts of potash, as the yellow ray is of the salts of soda. He concludes his paper with the following observation, which follows some remarks upon some experiments of Herschel's :-"If this opinion should be correct and applicable to the other definite rays, a glance at the prismatic spectrum of a flame may show it to contain substances which it would otherwise require a laborious chemical analysis to effect." In the Phil. Mag. for 1834, vol. iv. p. 114, Mr. Talbot further showed how, notwithstanding the similarity in colour of the light of lithia and strontia, they can at once be distinguished by means of the prism. He says the strontia flame exhibits a great number of red rays, well separated from each other by dark intervals, not to mention an orange and a very definite bright blue ray.

The lithia exhibits one single red ray. Hence I hesitate not to say that optical analysis can distinguish the minutest portions of these two substances from each other with as much certainty, if not more, than any other known method. He then describes the spectra produced by the flame of cyanogen.

In a paper in vol ix. of the same journal, p. 3, 1836, Mr. Talbot again adverts to the importance of the study of coloured flames, and describes the spectra of the salts of copper, of boracic acid, and nitrate of baryta, and corroborates, by independent experiment, the observations of Wheatstone on the electric spark.

The spectra of coloured flames were further examined, in 1845, by myself, and an account of these experiments was given in a paper read that year before the Chemical Section of the British Association at Cambridge. (Phil. Mag., xxvii. 81.

An alcohol lamp, fed with a solution of the compound, the flame of which was to be examined, and a common wick supported in a small glass tube, furnished the flame. The lamp was placed opposite the vertical slit, through which diffused daylight could be transmitted at pleasure. Fraunhofer's lines thus served as points of comparison of the different flames. The paper was illustrated by coloured lithographs of various spectra, the first that were published, including those of chloride of copper, boracic acid, nitrate of strontia, chloride of calcium, and chloride of barium, in minute detail.

Numerous other spectra were also described, including those of the chloride of sodium, manganese, and mercury, and of a large number of other metals. The paper concludes with the observation :-" It may be interesting to remark, in connection with the speculations on the absorptive action of the sun's atmosphere, that if solar light be transmitted through a flame exhibiting wellmarked black lines, these lines re-appear in the compound spectrum, provided the light of day be not too intense compared with that of the coloured flame. This may be seen in the red light of the nitrate of strontia, and less perfectly in the green of the chloride of copper. It would, therefore, appear that luminous atmospheres exist in which not only certain rays are wanting, but which exercise a positive absorptive influence on other lights."

The next paper of importance upon the prismatic analysis of artificial lights was published by Mr. Swan, in 1857. He, as early as the year 1847 (Edinburgh Phil. Trans.), in examining the double refraction of Iceland spar, pointed out the convenience of employing the principle of the collimator, which enables the slit through which the light is allowed to fall upon the prism to be brought up to within a very short distance of the prism itself. And in 1857 (Edin. Phil. Trans., vol xxi. p. 411), in the course of an elaborate investigation of the prismatic spectra of the flames of compounds of carbon and hydrogen, he indicated the extreme delicacy of the reaction for sodium. The bright yellow line characteristic of this metal he found could be produced by a quantity of a solution of common salt, which did not contain more than 500000th of a grain of sodium.

But it is to Kirchhoff and Bunsen (Poggendorff's Annal., cx. p. 161) that we are indebted for reducing the prismatic observation of flame tinged by the salts of different metals to a simple and systematic method of analysis for the alkalies and alkaline earths; and they have contrived an apparatus, of comparatively simple construction, by which the different spectra may be conveniently examined, and compared with one another. Fig. 1 exhibits the instrument in its most complete form (Poggendorff's Annal., cxiii. 374). It is an improvement

two spectra can be compared side by side. P represents a flint-glass prism, supported on the cast-iron tripod F, and retained in its place by the spring c. At the end of the tube A, nearest the prism, is a lens, placed at the distance of its focus for parallel rays from a vertical slit at the other end of the tube. The width of the slit can be regulated by means of the screw e. One-half of this slit is covered by a small rectangular prism, designed to reflect the rays proceeding from the source of light D down the axis of the tube, whilst the rays from the source of light E pass directly down the tube. By this arrangement, the observer stationed at the end of the telescope B is able to compare the spectra of both lights, which are seen one above the other, and he can at once decide whether their lines coincide or differ. a and b are screws for adjusting the axis of the telescope, so as to bring any part of the slit at e into the centre of the field of vision. The telescope, as well as the tube C, is movable in a horizontal plane, around the axis of the tripod. The tube C contains a lens at the end next to the prism, and at the other end is a scale divided into millimètres. When the telescope has been properly adjusted to the examination of the spectrum, the tube C is moved until it is placed at such an angle with the telescope and the face of the prism, that when a light is transmitted through the scale the image of this scale is reflected into the telescope from the face of the prism nearest the observer. This image is rendered perfectly distinct by pushing in the tube which holds the scale nearer to the lens in C, or withdrawing it to a greater distance, as may be required. The lines of the scale can then be employed for reading off the position of the bright or dark lines of the spectrum, as both will appear simultaneously, overlapping each other, in the field of the telescope. By turning the tube C round upon the axis of the tripod, any particular line of the scale can be brought to coincidence with any desired line of the spectrum. Stray light is excluded by covering the stand, the prism, and the ends of the tubes adjoining it with a loose black cloth.

The extraordinary delicacy of certain of these spectrum reactions was indicated by Swan, who measured it for sodium by the only accurate method,-namely, by dis

215

solving a weighed quantity of the salt in a known quantity of water, and he thus determined with precision the limit of the reaction. Bunsen and Kirchhoff attempted to estimate the sensitiveness of the reaction by

deflagrating a given weight of the various salts in the room in which they were experimenting, and diffusing the vapour mechanically through the air, increasing the quantity of the salt until a gas flame showed the reaction of the peculiar metal, due to particles in suspension. But it is obvious that this method does not admit of precision, and is liable to lead to an exaggerated estimate of the delicacy of the reaction, from the impossibility of ensuring uniformity in the diffusion of the salt.

The sodium reaction is the most sensitive of all; and so extensively is common salt diffused, that scarcely any flame can be obtained in which the indication of soda is absent.

Having observed the position of the bright lines produced by introducing into the flame of a Bunsen gas-burner the salts of the various alkalies and alkaline earths, each of which had been purified for these experiments with great care, they constructed a chart in which the different lines were laid down for each, and were able, by observing the position of the lines obtained when a mixture of various salts was introduced into the flame, to ascertain the presence of these different bases with sufficient readiness to use the method for the purposes of qualitative analysis. The rapidity with which the result is obtained by a practised observer, and the minuteness of the quantity required for the examination, give this method a superiority over any other now in use for the qualitative analysis for the alkalies and alkaline earths; moreover, the circumstance that the mere inspection of a source of light furnishes information respecting the composition of the bodies undergoing combustion or volatilisation, extends the mode of inquiry over distances limited only by the distance through which the object is visible; we are thus furnished with a method of analysis which is applicable to the luminous atmosphere of the sun, the stars, as well as to the light of the planetary bodies. This circumstance invests the subject with an interest like that which attends the employment of the telescope; at the same time the minuteness of its search enables it to reveal, like the microscope, quantities of matter indefinitely small.

This minuteness in its scrutiny has already, in the hands of Bunsen and Kirchhoff, led to the discovery that many bodies, such as lithia and strontia, formerly supposed to be rare, are really widely distributed in minute quantities. It also led them to discover the two new alkalies, cæsia and rubidia,-the first named from caesius, "sky-coloured," in allusion to two characteristic blue lines in its spectrum; the second from rubidus, "dark red," owing to the existence in its spectrum of two red lines of remarkably low refrangibility.

These bases were found in the course of an examination by the prism of the residue of the mother-liquor from the Durkheim spring, when the occurrence of these hitherto unobserved lines induced Bunsen to make a minute chemical examination of the water which furnished them. The inquiry showed that in every ton of the original water about three grains of chloride of cæsium, and rather less than four grains of chloride of rubidium, were present. These two salts so closely