Chapter C: W. HEATON, F.I.C., F.C.S., Lecturer on Chemistry at the (14)

More than 1500 years ago the Chinese are said to have used a preparation of hemp, or _ma-yo_, to annul the pain attendant upon cauterisation and other surgical operations. Mandragora (mandrake) was employed for a similar purpose by the Greeks and Romans; and we learn that as early as the thirteenth century the vapour from a sponge filled with tinctures of mandragora, opium, and other sedatives was used for a similar purpose.

Baptista Porta, in his work on natural magic printed in 1597, mentions a quintessence extracted from medicines by somniferous menstrua, of the nature of which he leaves us in ignorance. This quintessence was to be preserved in leaden vessels very perfectly closed, lest the aura should escape, for the medicine would vanish away. Furthermore, he adds, "when it is used, the cover being removed, it is applied to the nostrils of the sleeper, who draws in the most subtle power of the vapour by smelling, and so blocks up the fortress of the senses, that he is plunged into the most profound sleep, and cannot be roused without the greatest effort." Dr Iron suggested that the volatile substance was sulphuric ether, which he says had been described more than fifty years before Porta wrote his book. In the year 1800 Sir Humphry Davy suggested the employment of nitrous oxide, or laughing gas, as it was then termed, for minor operations in surgery, and in 1828 Dr Hickman proposed carbonic acid as an anæsthetic. The vapour of sulphuric ether had been used in his practice by Dr Pearson as early as 1795, for the relief of spasmodic asthma. The fact that sulphuric ether was capable of producing insensibility was demonstrated by American physicians; viz. by Godwin in 1822, Mitchell in 1832, Jackson in 1833, and Wood and Bache in 1834; but the first practitioner to employ it to prevent the pain of an operation was Dr Morton, a Boston dentist, who successfully used it for this purpose in 1846. On the 19th of December of the same year Mr Liston, of University Hospital, London, and Mr Robinson, a dentist, operated upon patients who had been rendered insensible by means of the inhalation of the vapour of ether.

Throughout the year 1847 ether was employed as an anæsthetic both in England and France, but towards the end of that year the anæsthetic properties of chloroform were pointed out by Flourens. The first, however, to introduce this agent into surgical and obstetric practice was Dr I. T. Simpson, of Edinburgh. In 1849 a work on the inhalation of ether was published by Dr Snow, who afterwards introduced a new anæsthetic, viz. amylene, which was capable of producing effects similar to those of chloroform; but as two patients out of but a small number who inhaled the vapour of amylene died, this latter soon fell into discredit, and consequent disuse.

Except in dental practice, in which nitrous oxide gas is the anæsthetic invariably employed, chloroform is almost universally used in surgical operations, one advantage it possesses over ether being its much more rapid action, although this latter property must be regarded as one which constitutes the risk which, although very slight (when the exceedingly small per-centage of deaths resulting from its administration is taken into account), undoubtedly attends its inhalation.

Dr Sansom says of chloroform:--"The cause of its danger is its power of paralysing the cardiac and other motor sources of circulation. This property resides in large and sudden doses of its vapour." He strongly recommends its dilution by air and alcohols. He further remarks that all anæsthetics modify the endosmotic condition of the blood discs, and contends that they affect the supply of arterial blood by altering the calibre of the channels which convey it. He advocates the substitution of one anæsthetic for another during the inhalation.

Methylene dichloride, introduced by Dr B. W. Richardson, is said to possess the disadvantage of causing considerable depression.

The mode of administering these agents is by causing the patient to inhale their vapour mixed with air.

Sometimes they are poured on to a sponge or a handkerchief, or piece of lint, either of which is then applied to the mouth and nostrils of the patient in such a manner that the air which passes into his lungs is saturated with the vapour. Except in extemporised cases, however, this method is pretty well abandoned, a proper apparatus having supplanted the sponge or handkerchief, &c. Part of the apparatus consists of a graduated bottle containing the anæsthetic, by means of which the operator is enabled to tell how much of this latter is being consumed, and thus to regulate the quantity inhaled.

The first effect that results from the administration of anæsthetics is a form of intoxication, caused by the action of the anæsthetic agent on the cerebral lobes, and as this action extends to the cerebellum, the patient becomes incapable of directing his movements--an effect like that caused by intoxication from alcohol.

In the next stage the spinal cord is attacked, unconsciousness supervenes, and all powers of motion and sensation are lost. The individual is now said to be in a state of anæsthesia; but the heart continues to beat, respiration is not impeded, and the other essential functions of the body go on as usual.

Should, however, the exhibition of the anæsthetic agent be incautiously continued too long, the bodily temperature falls, the movements of respiration and circulation become impaired, the heart ceases its action, and death finally ensues. The introduction of anæsthetics into surgical practice has been of great and invaluable service to the operator. The patient being motionless and free from pain, the surgeon is enabled to perform the operation at his ease, and consequently more efficiently; moreover, in the reduction of dislocations and of hernia, the muscles being flaccid, the obstacle produced by their contraction is removed. M. Velpeau endeavoured to produce local anæsthesia, or insensibility of the part of the body to be operated upon, by means of a freezing mixture composed of ice and salt; this method, however, was found impracticable, and was soon abandoned. Since then local anæsthesia as introduced by Dr Richardson, when had recourse to, is effected by means of a spray of ether directed on the part, the intense cold produced by the rapid evaporation of the ether entirely depriving the part of sensation. It is said that the pain resulting from the application of this method is a great barrier to its use.

Amongst anæsthetics, nitrous oxide gas occupies an important place, its use, as before stated, being almost wholly confined to operations in dental surgery.[55] As in the case of ether, the American practitioners were the first to employ nitrous oxide as an anæsthetic. Attention was directed to its anæsthetic properties in 1844 by Mr Horace Wells, an American dentist, but little interest seems to have been awakened by his application of it, since it was not until 1863 that Dr Cotton, of New York, drew attention to the subject by performing an operation on a patient under its influence.

[Footnote 55: The 'British Medical Journal' for 1868 states it was used successfully at the Ophthalmic Hospital, Moorfields.]

In March, 1868, Dr Evans, residing in Paris, after a visit from Dr Cotton, directed the attention of medical men in England to the value of nitrous oxide as an anæsthetic in dental surgery, and shortly afterwards it was first employed to produce anæsthesia at the Dental Hospital. Nitrous oxide is obtained from nitrate of ammonia, and the particulars of its preparation may be found by referring to the article NITROUS OXIDE.

Immense quantities of the gas are used in dental operations. It has been computed that in 1870 Messrs Coxeter and Barth could not have prepared much less than 60,000 gallons in London alone. To fit it for transit it is reduced by compression. Fifteen gallons may thus be diminished in volume until it fills an iron bottle holding a quart. Five or six gallons of the gas are, on an average, required for each patient. In the preparation of nitrous oxide for surgical purposes Dr Evans advises it to be made at least 24 hours before it is used, and further recommends its being thoroughly washed. An apparatus for the preparation of the gas was devised by Mr Porter, a description of which will be found in the 'Transactions of the Odontological Society of Great Britain' for 1868, in which also mention is made of a face-piece for its administration, the invention of Mr Clover. By means of this latter instrument the desiderata that the nitrous oxide should be inhaled without admixture with atmospheric air, and contamination arising from the expired air given off by the patient, are accomplished, for it has been found that when excitement and talking attend the inhalation of the gas, these effects are due to the presence of the carbonic acid thrown off by the lungs.

When inhaled in the ordinary way, nitrous oxide gas induces exhilaration and narcotism, without asphyxia. When, however, the atmospheric air is carefully excluded, it produces, as we have just seen, anæsthesia without exhilaration. The time required to produce anæsthesia varies from 25 to 120 seconds, by from 10 to 60 inhalations. A patient has been subjected for 10 minutes to its action without experiencing any unpleasant symptoms or after effects. Mr Randle says it is perfectly safe in all short operations, and possibly in long ones also, provided there is due admission of air at proper intervals. It seems tolerably certain that nitrous oxide is largely absorbed by the blood-corpuscles, and it is probable that its presence in them may temporarily act to the exclusion of oxygen, and thus prevent for a time that combination of oxygen with hæmoglobin upon which the red colour of the corpuscles depends. Chemistry, however, has failed to show that nitrous oxide is decomposed in the blood, or that it exerts any of the chemical properties of oxygen on the constituent elements of the blood. Whenever the slightest anæsthetic effect is communicated to the nervous system, a simultaneous effect is produced upon the medulla oblongata, the spinal chord, as well as upon the cerebrum and cerebellum.

The whole available force in the body is undoubtedly due to oxidation. This oxidation is accomplished by means of the blood, and it is therefore evident that a continuous flow of oxygenated blood to the nerve centres is necessary as a source of power and of sensibility, as well as for the reintegration of nerve tissue. Any deficiency of oxygen in the blood is followed by a decreased arterialisation of the whole volume of the blood. Under these conditions the exhalation of carbonic acid is relatively less rapid than its formation, and life cannot continue if the blood in the arteries becomes thoroughly venous, as well in colour as in character. That nitrous oxide, when inhaled, changes the colour of the blood-corpuscles is evidenced by the livid appearance of the face and mucous surfaces; the latter, indeed, is a characteristic accompaniment of its administration, and the darkened colour of the blood may be observed as it flows from the severed vessels. This colour of the blood is probably in part due to uneliminated carbonic acid; but that nitrous oxide possesses in a high degree the property of darkening the blood-corpuscles may be easily demonstrated by directing a jet of the gas for a few seconds upon a little arterial blood in a test tube. Yet, from what has previously been advanced on this point, this latter result may more strictly be due to physical than to chemical causes. An interruption of the circulation in any part of the organism is soon followed by local insensibility in the tissues from which the blood supply may have been withdrawn; and it is beyond dispute that, during the anæsthetic state, the circulation of the blood through the capillary system becomes diminished in velocity. A tendency to stasis begins to appear, accompanied at the same time by a considerable reduction in the supply of arterial blood. These are facts that admit of experimental demonstration, as does also another fact, viz. that during the period of insensibility produced by the inhalation of nitrous oxide the brain itself is in a state of comparative anæmia. In short, it appears most probable that an arrest of the capillary circulation through the brain, to which several writers have attributed a potential influence as the cause of anæsthesia, is simply, so far as it may exist, a result of it.

The anæsthesia produced by the inhalation of nitrous oxide would, therefore, appear to be referable to an altered condition of the blood, whereby the molecular dynamic changes are interfered with, this interruption being probably due either to the retention of carbonic acid, or to the presence of nitrous oxide; or, as the result of both conditions, to the exclusion of oxygen.

For minor operations nitrous oxide possesses many advantages over other anæsthetics. The principal of these is its safety. In America, in 200,000 cases in which it had been administered, there was only one case of death. Furthermore its use is not contra-indicated in patients having any constitutional derangement, nor for women who are either pregnant or suckling.

Nitrogen, coal-gas, and carbonic acid have also been employed as anæsthetics.

The 'British Medical Journal' for June 13th, 1868, contains an account of some experiments performed by Dr Burdon Sanderson, at Middlesex Hospital, with nitrogen. It seems to have been longer in producing insensibility than nitrous oxide, but no lividity of countenance accompanied, nor sickness or headache followed, its administration.

=ANALEP'TIC.= _Syn._ ANALEP'TICUS, L.; ANALEPTIQUE, Fr. Restorative; that recruits the strength lost by sickness.

=Analep'tics.= _Syn._ ANALEP'TICA, L.; ANALEPTIQUES, Fr. In _pharmacology_, &c., restorative medicines and agents.

=ANAL'YSIS= (-e-s[)i]s). [Eng. L., Gr.] _Syn._ ANALYSE, Fr.; AUSLÖSUNG, ZERLEGUNG, Ger. In a gen. sense, the resolution of anything, whether an object of the senses or of the intellect, into its elementary parts. In _chemistry_, the resolution or separation of a compound body into its constituent parts or elements, for the purpose of either determining their nature, or, when this is known, their relative proportions. It is divided into QUAL'ITATIVE ANALYSIS and QUAN'TITATIVE ANALYSIS; and these again into PROX'IMATE ANALYSIS and UL'TIMATE ANALYSIS. The first consists in finding the components of a compound, merely as respects their nature or names; the second, in finding not merely the component parts, but also the proportions of each of them; the third gives the results in the names of the proximate or immediate principles or compounds which, by their union, form the body under examination; whilst the fourth develops the chemical elements of which it is composed.[56] An analysis may also be made to determine whether a certain body is or is not contained in a compound (as lead in wine); or it may be undertaken to ascertain all the constituents present; the extent of an investigation being merely limited by the object in view.

[Footnote 56: Thus, suet consists of olein, palmitin, and stearin. These would form the 'terms' of the PROXIMATE ANALYSIS of this substance. But olein, palmitin, and stearin consist of carbon, hydrogen, and oxygen. The ULTIMATE ANALYSIS of suet would, therefore, have reference to the elements carbon, hydrogen, and oxygen.]

For success in chemical analysis a thorough acquaintance with the various properties of bodies is required, as well as aptitude in applying this knowledge in discriminating them, and separating them from each other. Judgment and expertness in manipulation are, indeed, essential qualifications. The method pursued must likewise be such as to attain the object in view with unerring certainty, and in the most expeditious manner. "The mere knowledge of the reagents, and of the reactions of other bodies with them, will not suffice for the attainment of this end. This requires the additional knowledge of a systematic and progressive course of analysis, or, in other words, the knowledge of the order, and succession, in which solvents, together with general and special reagents, ought to be applied, both to effect the speedy and safe detection of every individual component of a compound or mixture, and to prove with certainty the absence of all other substances. If we do not possess this systematic knowledge, or if in the hope of attaining an object more rapidly, we adhere to no method in our investigations and experiments, analysing becomes (at least in the hands of a novice) mere guesswork, and the results obtained are no longer the fruits of scientific calculation, but mere matters of accident, which sometimes may prove lucky hits, and at others total failures." (Fresenius.)

=ANALYSIS, SPECTRUM.= More than half a century ago Sir John Herschel employed the prism in the analysis of coloured flames, and in 1834 Fox Talbot, by means of the same instrument, distinguished the difference between the spectra given by strontium and lithium, notwithstanding the similarity of the two in colour. But it was reserved for Messrs Kirchkoff and Bunsen, as the inventors of the spectroscope, to devise the only efficient method of analysing flame, and, at the same time, to furnish chemists with a means whereby they may detect with unerring certainty the presence of any known element by observing the spectrum it gives when such element is submitted to a temperature sufficiently high for it to emit a luminous vapour. That certain chemical substances when heated in the flame of the spirit-lamp or the blow-pipe, or any other source of comparatively white light, imparted characteristic colours to the flame, was a fact that had long been known to chemists; for example, when a salt of sodium was so treated, an intense yellow colour was imparted to the flame. A salt of potassium produced under the same circumstances a violet, strontium, a crimson colour, &c. These results could only be produced when the substance under examination contained but one of the salts in question. If more than one were present, this method of qualitative analysis was comparatively, if not wholly, valueless, because the specific colour communicated to the flame by the presence of one element would be masked, and, consequently, destroyed by the colour developed by the vapour of another or other elements. For instance, so much more vivid is the yellow colour given to flame by sodium salts than the violet tint imparted by those of potassium, that a very small trace of sodium prevents the unaided eye from perceiving the violet, even when the potassium compound is present in large quantity.

Very different optical effects, however, follow if the rays from the various-coloured flames are made to pass through a prism. As is well known, if a ray of ordinary white light is made to traverse a prism, when it issues from the prism it has become decomposed or dissected into seven luminous rays of as many different colours, the coloured image thus produced being called a prismatic spectrum, or simply a spectrum.

This phenomenon is owing to the prism refracting or bending out of its course the beam of light sent through it, and to each coloured ray of which the beam is made up being differently refracted.

"If, however, instead of the white flame coloured flames are examined by means of a prism, the light being allowed to fall through a narrow slit upon the prism, it is at once seen that the light thus refracted differs essentially from white light, inasmuch as it consists of only a particular set of rays, each flame giving a spectrum containing a few bright bands. Thus, the spectrum of the yellow soda flame contains only one fine bright yellow line, whilst the purple potash flame exhibits a spectrum in which there are two bright lines, one lying at the extreme red, and the other at the extreme violet end. These peculiar lines are always produced by the same chemical element, and by no other known substance; and the position of these lines always remains unaltered. When the spectrum of a flame tinted by a mixture of sodium and potassium salts is examined, the yellow ray of sodium is found to be confined to its own position, whilst the potassium red and purple lines are as plainly seen as they would have been had no sodium been present."[57]

[Footnote 57: Roscoe.]

Equally characteristic and well-defined spectra, the bands in which have each an invariable and fixed position in the spectrum, are also produced when the coloured flames arising from heating to the requisite point the remaining salts of the alkalies and alkaline earths are examined by the prism. On the opposite page the first spectrum shows some of the fixed dark lines that are always observed when a solar beam is examined by the spectroscope. These lines are compared with the position of some of the more important bright lines furnished by the spectra of the metals of the alkalies and alkaline earths, when their chlorides are heated upon a loop of platinum wire introduced into the flame of a Bunsen gas-burner. The characteristic bright lines given by each metal are denoted by the letters of the Greek alphabet, the earliest letter indicating the most strongly marked lines.

In the potassium spectrum the most characteristic bright lines are the red line K [Greek: a], and violet line K [Greek: b]. In the case of sodium nearly the whole of the light is concentrated on the intense yellow double line Na [Greek: a]. In the lithium spectrum a crimson band, Li [Greek: a], is the prominent line; Li [Greek: b] is seldom visible, but at the elevated temperature of the voltaic arc an additional blue line becomes very intense. In the spectrum of cæsium two lines in the blue, Cs [Greek: a] and Cs [Greek: b], are strongly marked. In rubidium the lines Rb [Greek: a] and Rb [Greek: b] in the blue, and Rb [Greek: g] in the red are almost equally specific. Thallium is recognised by the intense green line Il [Greek: a]. The spectra of the metals of the alkaline earths are equally definite, though more complicated.

By means of the spectroscope quantities so inconceivably minute as the 33,000th of a grain of chloride of rubidium, the 170,000th of a grain of chloride of cæsium, the 2,500,000th of a grain of sodium, and the 6,000,000th of a grain of lithium, have been detected, and have revealed themselves to the sight by their characteristic bands in the spectrum. Hence it is that in making use of this branch of analysis the chemist has been enabled to show the universality of many elements hitherto regarded as being very sparingly distributed throughout the globe.

Thus lithium, which until lately was supposed to be one of the rare elements, has been found as a constituent of tea, tobacco, milk, blood, and in almost all spring waters. Furthermore, the prodigiously sensitive reactions afforded by the spectroscope have not only revealed the presence of infinitesimal quantities of known elements, but have led to the discovery of new ones which had escaped detection by the older and less delicate processes of analysis. It was by means of spectrum analysis that the two alkali metals, cæsium and rubidium, were discovered by Bunsen and Kirchkoff in 1860 in a mineral water at Durkheim, and that Mr Crookes in 1861 discovered the metal thallium in the deposit found in the flue of a pyrites furnace; whilst still more recently Messrs Reich and Richter, in a spectrum examination of a zinc ore from Freiberg, discovered the metal indium.

The most brilliant spectra are given by those salts which are the most easily volatilised, such as the chlorides, iodides, and bromides of the different metals. But it is only the metals of the alkalies and alkaline earths that give spectra that are characteristic. When it is desired to obtain the spectra of the other metals, they may be raised to the requisite temperature by means of the electric spark, which in passing through the two points of the metal operated upon volatilises a minute quantity of it, and thus enables it to emit its particular light. The electric sparks are best obtained by means of Ruhmkorff's coil. Thus each metal may be made to yield a spectrum which specially belongs to it, and to it alone. When the electric discharge is sent through a compound gas or vapour, owing to the intense temperature generated separation of its constituents must take place, since the spectra produced are those of the elementary components of the gas. The permanent gases give each their peculiar spectrum when they are strongly heated, by which they may be recognised; thus the spectrum of hydrogen is composed of three bands, one being bright red, one green, and the other blue. Nitrogen gives a very complicated spectrum.

The accompanying figure exhibits a very complete form of the spectroscope adapted to a single prism.

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 moveable 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 formed by transparent lines on an opaque ground; it is provided with a levelling screw, _d_. 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 reflected lines of the scale can then be employed for reading off the position of the dark or bright 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 tube adjoining it with a loose black cloth. The dispersive power upon the spectrum may be much increased by using several prisms instead of one. Kirchkoff used four prisms in his experiments upon the solar spectrum. Great care must be observed in placing the prisms; the refracting edge of each prism must be exactly vertical, and the position of minimum deviation for the rays to be observed must be obtained.

The preceding remarks have reference to the spectra produced when the vapours of certain elements are evolved in flame derived from artificial sources. When, however, solar light is examined by the spectroscope, results entirely the reverse follow.

If a beam of sunlight be sent through the slit of the spectroscope, the prismatic image is seen to be intersected by a number of fine black lines, varying in thickness and intensity, and invariably occupying the same relative position in the solar spectrum. These lines were first noticed so far back as 1815 by a German optician, Frauenhofer, after whom they were named Frauenhofer's lines; but it was not until the invention of the spectroscope that the origin of these lines could be accounted for. By so arranging the instrument as to cause the spectrum from a solar beam, and that from a metallic element, to fall upon the field of the telescope, so that the solar spectrum shall be above the other, both being perfectly parallel; the bright bands or lines of the metal are all seen to be continued in the dark solar lines, for, as may be seen by consulting the plate of the different spectra, several lines are sometimes produced by one element alone. If, for instance, the sodium and solar spectra are thus compared, the bright yellow sodium line will be found to agree exactly not only in position, but also in intensity and breadth, with one of the dark solar ones. And the same thing occurs when the comparison is made with many of the other metals, the bright lines in the respective spectra furnished by them are each coincident with a particular dark line in the solar spectrum, and from every dark line in the latter a corresponding bright one can be found amongst the spectra of the metals. From what has just been stated, the inference seems irresistible that this coincidence between the dark solar lines and the bright lines of the metals cannot be accidental, but must be due to some intimate connection between them, and that this is the case can be proved beyond refutation by a simple experiment, in which the bright metallic lines can be changed into dark ones, corresponding in every particular with those of the solar spectrum. Thus the bright yellow soda lines coincident with Frauenhofer's lines can be converted into dark ones by allowing the rays from a strong source of white light to pass through a flame coloured with sodium, and then making them fall upon the slit of the spectroscope. If we examine the spectrum obtained by this means, instead of seeing the usual bright double band upon a black ground, there will be presented to our sight a double dark line, corresponding exactly with the position and width of the sodium line, and instead of the black ground there will be a continuous spectrum of white light, as in the solar spectrum.

The explanation of this remarkable phenomenon is due to Kirchkoff, and is as follows:--When any substance is heated sufficiently to render it luminous, rays of a certain and definite degree of refrangibility are given out by it; whilst the same substance has also the power of absorbing rays of this identical refrangibility. In the above experiment, therefore, the yellow flame absorbed the same kind of light as it gave out, a corresponding decrease of intensity in its own particular position in the spectrum occurred, and a dark line showed itself in consequence.

In the same manner and under similar conditions the spectra of many other substances have been reversed.

Reasoning on these facts, Kirchkoff has been able to account for the presence in the solar spectrum of Frauenhofer's dark lines. He supposes that in the luminous atmosphere surrounding the sun the vapours of various metals are present, each of which would give its characteristic system of bright lines; but behind this incandescent atmosphere containing metallic vapour is the still more intensely heated solid or liquid nucleus of the sun, which emits a brilliant continuous spectrum, containing rays of all degrees of refrangibility.

When the light of this intensely heated nucleus is transmitted through the incandescent photosphere of the sun, the bright lines which would be produced by the photosphere are reversed, and Frauenhofer's dark lines are only the reversed bright lines which would be visible if the intensely heated nucleus were no longer there.

The correctness of this theory has been rigorously tested by Kirchkoff himself, who submitted the solar spectrum to a most minute and searching examination.

As a result of the knowledge thus obtained, the presence of certain metals in the sun's atmosphere was an inevitable deduction. The metals hitherto detected in the solar photosphere are--iron, sodium, magnesium, calcium, chromium, nickel, barium, copper, zinc, strontium, cadmium, cobalt, manganese, aluminium, and titanium. Hydrogen also exists in large quantity as an incandescent gas, and gives rise to the red protuberances that may be observed during a total eclipse.

During the total eclipse of 1869, M. Janssen, a French astronomer, was enabled to obtain and figure the specimen of these red protuberances, which, taken exclusively from that source of light, gave not dark lines, but bright ones, corresponding in position with those of hydrogen, magnesium, and sodium.

The fixed stars, unlike the moon and planets, which shine only by reflected light, are not merely illuminated by self luminous bodies, and yield spectra, which show them to contain many elements known to us; their spectra are crossed by dark lines similar to, but not identical with those given by the sun's light. The spectrum yielded by the star Aldebaran shows it to contain hydrogen, sodium, magnesium, calcium, iron, tellurium, antimony, bismuth, and mercury; in the spectrum of Sirius only sodium, magnesium, and hydrogen have been found; whilst in that of Orionis there is an absence of hydrogen. Most of the nebulæ and comets give spectra in which there are only bright lines. It is hence inferred that these celestial bodies are composed of masses of glowing gas, and, unlike the sun and stars, do not consist of a solid or liquid mass surrounded by a gaseous atmosphere. In the nebulæ hydrogen and nitrogen only have been found; and in comets, principally carbon.

=ANANAS HEMP= (_Ananassa sativa_, _S. Brumelia ananas_, as well as other species). This hemp comes from the West Indies and Central and South America, where the common ananas is cultivated. It is rather inferior to some varieties for spinning.

=ANASTATIC PRINTING.= See PRINTING and ZINCOGRAPHY.

=ANATHERIN BALSAM.= The following formula is published by the Netherlands Society:--Tincture of myrrh, 160 grms.; tincture of catechu, 80 grms.; tincture of guaiacum, 40 grms.; tincture of rhatany, 40 grms.; tincture of cloves, 30 grms.; spirit of cochlearia, 20 grms.; oil of cassia, 20 drops; otto of roses, 1 drop; proof spirit, 630 grms.

=ANATHERIN BALSAM= (J. G. Popp, Vienna). A mouth-wash. Red sandal wood, 20 parts; guaiacum wood, 10 parts; myrrh, 25 parts; cloves, 15 parts; cinnamon, 5 parts; oils of cloves and cinnamon, of each, 2/3 part; spirit, 90 per cent., 1450 parts; rose water, 725 parts. Digest and filter.

Dr Hager, who gives the above, says that on the expiration of the patent the following formula was published, but that a preparation made from that process had only a distant resemblance to the actual compound. Myrrh, 1 part; guaiacum wood, 4 parts; saltpetre, 1 part; to be macerated for a night with corn brandy, 120 parts; spirit of cochlearia, 180 parts. Then distil of this 240 parts, in which are to be digested for 14 days garden rue, cochlearia, rose leaves, black mustard, horseradish, pellitory root, cinchona bark, club-moss, sage-vetiver, and alkanet root, of each 1 part. Strain and filter, and to each 120 parts of the filtrate add 1 part of spirit of nitrous ether. (Hager.)

=ANATOM'ICAL.= _Syn._ ANATOM'ICUS, L.; ANATOMIQUE, Fr.; ANATOMISCH, Ger. Belonging to anatomy or dissection.

=Anatomical Prepara'tions.= Objects of interest in both surgical and pathological anatomy, and specimens in natural history, preserved by subjecting them to antiseptic processes, to which is also frequently added injection with coloured fluids (which subsequently harden), amalgams, or fusible metal, in order to display more fully the minute vessels, or the microscopic anatomy of the several parts. See FUSIBLE ALLOY, INJECTIONS, PREPARATIONS, PUTREFACTION, SKELETONS, SOLUTIONS, &c.

=ANCH'OVY= (-ch[=o]'-). _Syn._ ANCHOIS, Fr.; ANCHOVE, ANSCHOVE, Ger.; ACCIUGHE, ANCHIOVE. It.; ANCHOVA, Port., Sp. The _clu'pea encrasic'olus_ (Linn.), a small fish of the herring tribe, closely resembling the English sprat. It is common in the Mediterranean, and occurs in the greatest abundance and of the finest quality about the island of Gorgona, near Leghorn. It is taken in the night, during May, June, and July.

Anchovies are prepared for sale or exportation by salting or pickling them--the heads, intestines and pectoral fins having been first removed, but not the scales, and afterwards packing them, along with rock-salt, in the small kegs in which they are imported into this country. The small fish are valued more than the larger ones. For the table they are often fried to a pale amber colour, in oil or butter; having previously been scraped clean, soaked for an hour or two in water, wiped dry, opened (without dividing the fish), and had the back-bones removed. Before being put into the pan they are usually highly seasoned with cayenne; and after being again closed, are dipped into a rich light batter. They are also divided into fillets, and served as sandwiches, or in curried toasts. Anchovies are also extensively potted (POTTED ANCHOVIES), and made into butter (A.-BUTTER), and into sauce (A.-SAUCE), particularly the last.

The anchovy has a fine and peculiar flavour, and is eaten as a delicacy all over Europe. It was known to the Greeks and Romans, who prepared from it a kind of garum for the table. It is said to be aperitive, stimulant, and stomachic.

The high price of genuine Gorgona anchovies has led the fraudulent dealer to either substitute for them, or mix with them, fish of a less expensive kind. The most frequent SUBSTITUTIONS are Dutch, French, and Sicilian fish of allied species or varieties, sardines and even the common sprat. The genuine Gorgona fish is about the length of one's finger; and may be known by its silvery appearance; by the greater thickness of its head, which is sharp-pointed, with the upper jaw considerably the longest, and the mouth deeply divided; the dusky brown colour of its back,[58] and the pink salmon colour of its flesh. When only 3 months old, its flesh is pale; when of 6 months, rather pink; when of 10 to 12 months (or in its prime), a beautiful deep pink colour; and when much older, darker, but less lively. The fin-rays, varying in number with the age of the fish, are--

Yarrell. Hassall.[59]
Dorsal 14, 16 (?).
Pectoral 15, --
Ventral 7, --
Anal 18, 19 (?).
Caudal 19, 26 (?).

These fins are delicate in structure and greenish-white; and the membranes connecting the rays almost transparent. "The length of the head, compared with the length of the body alone, is as 1 to 3; the depth of the body but 2-3rds of the length of the head, and compared to the length of the whole fish is as 1 to 7;" the tail is deeply forked, the gill covers are elongated, and the scales of the body large and deciduous." "The breadth of the eye is 1-5th of the length of the whole head."[60] Dutch fish may be generally known by being deprived of the scales, and the French fish by their larger size; and both by the paler or whiter colour of their flesh; and sardines and sprats by the flesh being white. The genuine fish may also be known by the pickle, after repose or filtration, being of a clear pinkish colour, without any red sediment; whilst that from spurious kinds is turbid and red only when agitated, and deposits a heavy red sediment (Armenian bole, Venetian red, or red ochre) on repose. See BUTTER, POTTING, POWDERS, SAUCES, &c.

[Footnote 58: The colour of the top of the head and back is, in the recent fish, blue, with a tinge of green. (Yarrell.)]

[Footnote 59: Counted, by Dr A. H. Hassall, in fish in the preserved state.]

[Footnote 60: Yarrell's 'British Fishes'.]

=Anchovies, Brit'ish.= See SPRATS.

=ANCHU'SIC ACID= (-k[=u]'z[)i]k). See ANCHUSINE.

=ANCHU'SINE.= (-k[=u]'z[)i]n). [Eng., Fr.] _Syn._ ANCHU'SIC ACID*, PSEU'DO-ALKANN'INE*, PSEUDO-ALKA''NIUM*; ANCHUSI'NA, L. The resinoid constituting the colouring matter of alkanet-root (which _see_).

=ANCHYLO'SIS= ([)a]ngk-e-). [L.; prim. Gr.] _Syn._ ANKYLO'SIS, ANCYLO'SIS ([)a]n-se-), L.; ANKYLOSE, Fr., Ger. In _pathology_, stiffness or immobility of a joint naturally moveable. Anchylosis is either true or complete, as when the extremities of the bones forming a joint are reunited and immovable; or false, or incomplete, where the affection depends upon a contraction of the tendons and ligaments surrounding the joints, which nevertheless admit of a small degree of motion. For the first there is no available remedy; for the second gentle and progressive flexion and extension of the part daily (carefully avoiding violence), friction with oleaginous and stimulating liniments, and the use of the hot bath, vapour bath, or hot-air or Turkish bath, and electricity, have been strongly recommended, and have frequently proved successful.

=ANCYLO'SIS.= See ANCHYLOSIS.

=ANDITROPFEN= (Kirchner and Menge Arolsen), for weak digestion. Senna, 20 parts; rhubarb, 3 parts; jalap, 6 parts; zedoary root, 2 parts; ginger, 2 parts; galangal, 3 parts; soda, bicarbonate, 5 parts; sugar, 15 parts; water, 300 parts; spirit, 65 parts. After digestion this is to be strained and mixed with an infusion of 30 parts of yarrow (with the flowers) in 300 parts of hot water. After standing some time filter. (Hager.)

=ANDROGRAPHIS PANICULATA.= (Ind. Ph.) _Syn._ KARIYÁT. _Habitat._ Commonly in shady places all over India.--_Officinal part._ The dried stalks and root (Andrographis Caules et Radix, Kariyat, Creyat). The stem, which is usually met with, with the root attached, occurs in pieces of about a foot or more in length, quadrangular, of a lightish-brown colour, and persistent bitter taste.--_Properties._ Bitter tonic and stomachic, very analogous to quassia in its action.--_Therapeutic uses._ In general debility, in convalescence after fevers, and in the advanced stages of dysentery.

_Preparations_:--

=Compound Infusion of Kariyát= (Infusum Andrographis compositum). Take of Kariyát, bruised, 1/2 an ounce; orange-peel and coriander fruit, bruised, of each, 60 grains; boiling water, 10 fluid ounces. Infuse in a covered vessel for an hour and strain.--_Dose._ From 1-1/2 to 2 fluid ounces, twice or thrice daily.

=Compound Tincture of Kariyát= (Tinctura Andrographis composita). Take of kariyát root, cut small, 6 ounces; myrrh and aloes, in coarse powder, of each 1 ounce; brandy, 2 pints. Macerate for seven days in a closed vessel, with occasional agitation; strain, press, filter, and add sufficient brandy to make two pints.--_Dose._ From 1 to 4 fluid drachms. Said to be tonic, stimulant, and gently aperient, and to prove valuable in several forms of dyspepsia, and in torpidity of the bowels.

=ANDROPOGON (CYMBOPOGON) CITRATUM.= Lemon Grass. (Ind. Ph.) _Habitat._ Commonly cultivated in gardens in India; also in Ceylon, upon a large scale, for the sake of its volatile oil.--_Officinal part._ The volatile oil (Oleum Andropogi Citrati, Lemon Grass Oil, Oil of Verbena), obtained by distillation from the fresh plant; of a pale sherry colour, transparent, extremely pungent taste, and a peculiar fragrant lemon-like odour.--_Properties._ Stimulant, carminative, antispasmodic, and diaphoretic; locally applied, rubefacient.--_Therapeutic use._ In flatulent and spasmodic affections of the bowels, and in gastric irritability. In cholera it proves serviceable by aiding the process of reaction. Externally, as an embrocation in chronic rheumatism, neuralgia, sprains, and other painful affections.

_Dose._ From 3 to 6 drops, on sugar or in emulsion. For external application it should be diluted with twice its bulk of soap liniment or any bland oil.

=ANDROPOGON (CYMBOPOGON) NARDUS.= CITRONELLE. (Ind. Ph.) _Habitat._ Madras Peninsula and Ceylon. The volatile oil of this plant has similar properties to _A. citratum_. and is used for the same purposes.

=ANDROPOGON PACHNODES.= (Ind. Ph.) The volatile oil of this plant possesses similar properties to that of _A. citratum_, and is used for the same purposes.

=ANELEC'TRIC= ([)a]n-e-). Non-electric; a non-electric.

=ANEMOM'ETER= ([)a]n-e-). _Syn._ ANEMOM'ETRUM, L.; ANÉMOMÈTRE, Fr.; WINDMESSER, Ger. An instrument or apparatus for measuring the force or velocity of the wind, or of a current of air. Various contrivances have been adopted for this purpose. The anemometer of Dr Lind being also applicable to the determination of the draught of a chimney, and the strength of air-current, in ventilation, may be usefully described here:--

_Uses and Appl._ The open end (_a_) is kept, by means of a vane, presented to the wind, which acting on the surface of the water, or other liquid in _b_, raises the level of the fluid in the arm (_c_). The difference of the level of the fluid in the two arms of the instrument is the measure of the force of the wind. To estimate the draught of a flue or chimney, the arm (_c_) is placed in the chimney, and the orifice (_a_) in the apartment.[61]

[Footnote 61: The anemometers now generally used in meteorological observations are those of Mr Follet Osler, Dr Robinson, and Dr Whewell. For a description of these instruments, see Phillip's 'Report on Anemometry,' the 'Trans. of the Brit. Assoc.,' 1846, 'Trans. Royal Irish Acad.,' &c.]

=ANEMOM'ETRY.= _Syn._ ANEMOME'TRIA, L.; ANÉMOMETRIE, Fr.; WINDMESSEN, Ger. In _meteorology_, _physics_, &c., the art or act of measuring the velocity or force of the wind, or of ascertaining its direction.

=ANEM'ONE= ([)a]-n[)e]m'-o-ne). _Syn._ ANEM'ONY; ANEM'ONE, L., Gr.; ANÉMONE, Fr. The wind-flower. In _botany_, a genus of beautiful flowering herbaceous plants, of the nat. ord. Ranunculaceæ. The double flowers of some of the species are among the most elegant ornaments of our gardens. Others are used in medicine. They are all acrid and stimulating.

=Anem'ones, Sea.= (-o-n[=e]z). _Syn._ AN'IMAL-FLOWERS[double-dagger], SEA SUN'FLOWERS[double-dagger]. Animals of the genus _actin'ia_, so called from the resemblance of their claws or tentacles, when expanded, to the petals of a flower. They are of various colours, are generally fixed by one end to rocks or stones in the sand, and are very voracious, being accused of occasionally swallowing a mussel or a crab as large as a hen's egg for a meal. They belong to the highly organised polypes of Cuvier.

=ANEMON'IC ACID.= See ANEMONINE.

=ANEMONIN.= A crystalline substance found in the leaves of several species of anemone, viz. _A. pulsatilla_, _A. pretensis_, _A. nemorosa_. Water distilled from these leaves, after some weeks, deposits a colourless inodorous substance, which softens at 150° C, giving off water and acrid vapours. It is purified by repeated crystallisation from boiling alcohol. Anemonin is a poisonous body. It causes slight irritation when applied to the skin. By the action of alkalies anemonin is transferred into anemonic acid.

=ANEM'OSCOPE= ([)a]n'-e--Brande, Mayne). _Syn._ ANEMOSCO'PIUM, L.; ANÉMOSCOPE, Fr.; ANEMOSKOP, Ger. An instrument to measure the force and velocity of the wind. See ANEMOMETER.

=AN'EROID= (-royd)[62]. In _physics_, &c., not fluid, or not depending on water or a fluid for its action; applied to a certain form of barometer (which _see_)

[Footnote 62: That is--[Greek: a], _without_, [Greek: nêros], (the) _watery_, [Greek: eidos], _form_, as correctly given by Brande. By some strange mistake, Dr Mayne, in his new 'Expository Lexicon,' gives "[Greek: a], priv., [Greek: aêr], air, terminal _-ides_," as the derivation of this word; and marks it '_ane'roid_,']

=ANEURISM.= A tumour on an artery, produced by the rupture of the inner coat of the vessel, and the blood getting between it and the outer coat.

=ANGEL'ICA= (-j[)e]l'-). [L., Port., Sp.; Ph. E. & D.] _Syn._ GARDEN ANGELICA; ANGÉLIQUE, Fr.; ANGELIKA, A.-WURZEL, ANGELKRAUT, Ger. The _angelica archangel'ica_ of Linnæus, an aromatic herbaceous plant with a biennial, fleshy root, indigenous to the north of Europe, but frequently found wild in England, and largely cultivated in our gardens. Dried root (ANGELICA, Ph. E.), aperient, carminative, diaphoretic, and tonic; much esteemed by the Laplanders, both as food and medicine;--fruit or seed (ANGELICA, Ph. D.) resembles the root, but is weaker. The whole plant has been extolled as an aromatic tonic. As a masticatory, it leaves an agreeable glowing heat in the mouth. The aromatic properties of this plant depend on a peculiar volatile oil and resin.

_Uses, &c._ It has been recommended in diarrh[oe]a, dyspepsia, debility, and some fevers; but is now seldom used in medicine. _Dose_, 30 gr. to 1 dr. The dried root and seeds are used by rectifiers to flavour gin and liqueurs; and the fresh root, tender stems, stalks, &c., are made by the confectioners into an aromatic candy. See CANDYING, LIQUEURS, &c.

=Angelica Atropurpu''rea.= [Linn.] _Syn._ AMER'ICAN ANGELICA; ANGELICA, Ph. U. S. _Hab._ North America. Resembles garden angelica, but placed by some botanists in a separate, though allied genus. It is a popular remedy for flatulent colic, indigestion, and cardialgia, in the United States; and is there regarded as tonic, cordial, and aphrodisiac.

=ANGEL'IC ACID. HC_{5}H_{7}O_{2}.= A volatile substance, noticed by L. A. Buchner, jun., in angelica-root. It has a pungent sour smell, and a biting acid taste; is sometimes fluid and oleaginous, and sometimes crystallised in striated prisms.[63]

[Footnote 63: Schmidt's 'Jahrb.,' 1842.]

=ANGO'LA= _Syn._ ANGO'LA-WOOL, ANGO''RA-W., ANGO'NA-W., &c.; POIL DE CHEVRON D'ANGORA, Fr.; (Engoor', Engour', or Engu'ri) TIFTIC, Tur. The wool of 'ca'pra Angoren'sis' or the Angora-goat, of which the shawls of Cashmere are made, and others in imitation of them. It is also used to make plush, light cloths for paletôts which are repellent of wet, &c.; and is extensively employed in France in the manufacture of lace more brilliant than that of Valenciennes and Chantilly, and at half the price. See ALPACA, SHAWLS, WOOL, &c.

=ANGOSTU'RA, Angustu'ra.= (-t[=u]re'-[)a]). See CUSPARIA.

=Angostura, False.= See BRUCEA, CUSPARIA and STRYCHNOS.

=ANGOSTU''RINE=, =Angustu'rine= (-[)i]n). See CUSPARIN.

=ANHYDRIDE.= Most, if not all modern chemists, adopting GERHARDT'S practice of limiting the title of acid to a particular class of substances which contain hydrogen, now regard all true acids as salts of hydrogen. Formerly many bodies, such as silica or white arsenic, were looked upon as acids, though if we adopt the foregoing definition they are not really so until they have combined with water. Such bodies, because they contain no hydrogen, are now distinguished as anhydrides; the substances, for example, familiarly known as carbonic, sulphurous, and phosphoric acids, must, upon the above principle, be designated carbonic, sulphurous, and phosphoric anhydrides. We may also define an anhydride to be an oxide which forms an acid on treatment with water.

=ANHY'DROUS= (-dr[)u]s; _an'hydrous_, as marked by Brande, is less usual). _Syn._ AN'HYDRUS, L.; ANHYDRÉ, Fr.; WASSERFREI, Ger. Free from water; dry. In _chemistry_ and _mineralogy_, a term frequently applied to substances, as acids, alcohol, gases, salts, minerals, &c., which do not contain either free or combined water. GASES may generally be rendered anhydrous by passing them through a tube containing fused chloride of calcium, or (_e.g._ AMMONIA and two or three others) quick-lime, in coarse powder; and some of them, by passing them through concentrated sulphuric acid. SALTS may generally be dried by cautiously submitting them to the action of heat, or by exposure to a very dry atmosphere; and alcohol, and many other volatile fluids, by careful distillation from chloride of calcium, or some other highly hygrometric substance.

=AN'IL.= [Fr., Sp., L.] The indigof'era anil of botanists--one of the plants yielding 'indigo'--a native of America, but now largely cultivated in the East Indies. See INDIGO (and _below_).

=AN'ILINE=[64] (-een). [Eng., Fr.] C_{6}H_{7}N. _Syn._ PHENYL'AMINE; ANILI'NA, ANILI'NUM, &c., L. A peculiar volatile organic base first noticed by Unverdorben in empyreumatic bone-oil, and afterwards obtained by Runge from coal-tar, and by Fritzsche, Zinin, A. W. Hofmann, and others, as a product of various reactions, processes, and decompositions, particularly those attending the destructive distillation of organic bodies.

[Footnote 64: For a detailed account of the methods of preparing aniline commercially, and of the dyes obtained therefrom, _see_ 'Dictionnaire de Chimie,' par A. Wurtz.]

PREP. Aniline is now almost invariably obtained, on the large scale, either directly or indirectly from coal-tar or indigo; and chiefly from the basic oil or naphtha, or the nitrobenzol, of which the former is the principal source. The following are the leading commercial and experimental processes:

1. From COAL-TAR or COAL-TAR NAPHTHA:--The basic oil or basic portion of coal-tar or coal-tar naphtha, forming the latter, denser, and least volatile products of the distillation or rectification of these substances, is strongly agitated, for some time, along with hydrochloric acid in slight excess, a glass globe, or, on the large scale, a suitable vessel of lead, or of enamelled iron, being employed for the purpose; the clear portion of the liquid (containing the hydrochlorates of the bases present) is then decanted and carefully evaporated over an open fire until acrid fumes begin to be disengaged, when it is again decanted or filtered; the clear liquor, or filtrate is next treated with potash or milk of lime in excess, by which the bases--chiefly aniline and chinoline--are liberated under the form of a brownish oil; the whole of the resulting mixture is now submitted to distillation, the portion which passes over at or about 360° Fahr., and which consists chiefly of crude aniline, being collected separately; the product is purified by rectification and recollection, once or oftener, at the same temperature, and, lastly, by fresh treatment with hydrochloric acid and careful distillation with excess of potash, or milk of lime, as before.