Chapter XX: Front Matter (20)

Not less characteristic of its splendidly gifted and barbarically untameable author are the autobiographical memoirs which he composed, beginning them in Florence in 1558,--a production of the utmost energy, directness and racy animation, setting forth one of the most singular careers in all the annals of fine art. His amours and hatreds, his passions and delights, his love of the sumptuous and the exquisite in art, his self-applause and self-assertion, running now and again into extravagances which it is impossible to credit, and difficult to set down as strictly conscious falsehoods, make this one of the most singular and fascinating books in existence. Here we read, not only of the strange and varied adventures of which we have presented a hasty sketch, but of the devout complacency with which Cellini could contemplate a satisfactorily achieved homicide; of the legion of devils which he and a conjuror evoked in the Colosseum, after one of his not innumerous mistresses had been spirited away from him by her mother; of the marvellous halo of light which he found surrounding his head at dawn and twilight after his Roman imprisonment, and his supernatural visions and angelic protection during that adversity; and of his being poisoned on two several occasions. If he is unmeasured in abusing some people, he is also unlimited in praising others. The autobiography has been translated into English by Thomas Roscoe, by J.A. Symonds, and by A. Macdonald. Cellini also wrote treatises on the goldsmith's art, on sculpture, and on design (translated by C.R. Ashbee, 1899).

Among his works of art not already mentioned, many of which have perished, were a colossal Mars for a fountain at Fontainebleau and the bronzes of the doorway, coins for the Papal and Florentine states, a Jupiter in silver of life size, and a bronze bust of Bindo Altoviti. The works of decorative art are, speaking broadly, rather florid than chastened in style.

In addition to the bronze statue of Perseus and the medallions already referred to, the works of art in existence to-day executed by him are the celebrated salt-cellar made for Francis I. at Vienna; a medallion of Clement VII. in commemoration of the peace between the Christian princes, 1530, with a bust of the pope on the reverse and a figure of Peace setting fire to a heap of arms in front of the temple of Janus, signed with the artist's name; a medal of Francis I. with his portrait, also signed; and a medal of Cardinal Pietro Bembo. Cellini, while employed at the papal mint at Rome during the papacy of Clement VII. and later of Paul III., executed the dies of several coins and medals, some of which still survive at this now defunct mint. He was also in the service of Alessandro de' Medici, first duke of Florence, for whom he executed in 1535 a forty-soldi piece with a bust of the duke on one side and standing figures of the saints Cosmo and Damian on the other. Some connoisseurs attribute to his hand several plaques, "Jupiter crushing the Giants," "Fight between Perseus and Phinaeus," a Dog, &c.

The important works which have perished include the uncompleted chalice intended for Clement VII.; a gold cover for a prayer-book as a gift from Pope Paul III. to Charles V.,--both described at length in his autobiography; large silver statues of Jupiter, Vulcan and Mars, wrought for Francis I. during his sojourn in Paris; a bust of Julius Caesar; and a silver cup for the cardinal of Ferrara. The magnificent gold "button," or morse, made by Cellini for the cope of Clement VII., the competition for which is so graphically described in his autobiography, appears to have been sacrificed by Pius VI., with many other priceless specimens of the goldsmith's art, in furnishing the indemnity of 30,000,000 francs demanded by Napoleon at the conclusion of the campaign against the States of the Church in 1797. According to the terms of the treaty, the pope was permitted to pay a third of that sum in plate and jewels. Fortunately there are in the print room of the British Museum three water-colour drawings of this splendid morse by F. Bertoli, done at the instance of an Englishman named Talman in the first half of the 18th century. The obverse and reverse, as well as the rim, are drawn full size, and moreover the morse with the precious stones set therein, including a diamond then considered the second largest in the world, is fully described.

BIBLIOGRAPHY.--The autobiography already named is the foundation of
most of the works written concerning Cellini's life. See also
_Cellini, His Times and Contemporaries_, by "the Author of the Life of
Sir Kenelm Digby" (1899); L. Dimier, _Cellini a la cour de France_
(1898); Eugene Plon, _Cellini, orfevre, medailleur, &c._ (1883);
Bolzenthal, _Skizzen zur Kunstgeschichte der modernen Medaillen-Arbeit
1429-1840_ (Berlin, 1840); A. Armand, _Les Medailleurs italiens des
XVe et XVIe siecles_ (3 vols., Paris, 1883-1887); Dr Francesco Tassi,
_Vita di Benvenuto Cellini_ (Firenze, 1829), _Vita di Benvenuto
Cellini scritta da lui medisimo_ (1832); E. Babelon, _La Gravure en
pierres fines_ (Paris, 1894); A. Heiss, _Les Medailleurs florentins_
(Paris, 1887); J. Friedlander, _Die italienischen Schaumunzen des
funfzehnten Jahrhunderts_ (Berlin, 1880-1882); N. Rondot, _Les
Medailleurs lyonnais_ (Macon, 1897); Dr Julius Cahn, _Medaillen und
Plaketten der Sammlung W.P. Metzler_ (Frankfort-on-Main, 1898);
Molinier, _Les Plaquettes_; I.B. Supino, _Il Medagliere Mediceo nel R.
Museo Nazionale di Firenze_ (Florence, 1899); _L'Arte di Benvenuto
Cellini_ (Florence, 1901); C. von Fabriczy, _Medaillen der
italienischen Renaissance_ (Leipzig); L. Forrer, _Biographical
Dictionary of Medallists, &c._ (London, 1904), &c.
(W. M. R.; E. A. J.)

CELLULOSE, the name given to both an individual--cellulose proper, in the restricted sense of a chemical individual--and to a group of substances, the celluloses or cellulose group, which constitute in infinitely varied forms the containing envelope of the plant cell. They are complex carbohydrates, or "saccharo-colloids" (Tollens), and are resolved by ultimate hydrolysis into monoses. The typical cellulose is represented by the empirical formula C6H10O5, identical with that of starch, with which it has many chemical analogies as well as physiological correlations. The representative "cellulose" is the main constituent of the cotton fibre substance, and is obtainable by treating the raw fibre with boiling dilute alkalis, followed by chlorine gas or bromine water, or simply by alkaline oxidants. The cellulose thus purified is further treated with dilute acids, and then exhaustively with alcohol and ether. Chemical filter-paper (Swedish) is practically pure cellulose, the final purification consisting in exhaustive treatment with hydrofluoric acid to remove silicious inorganic residues. The "cellulose" group, however, comprises a series of substances which, while presenting the characters generally similar to those of cotton cellulose, also exhibit marked divergences. The resemblances are maintained in their synthetical reactions; but reactions involving the decomposition of the complex show many variations. For example, cotton cellulose is difficultly hydrolysed; other celluloses are more or less readily split up by dilute acids, the extreme members readily yielding sugars: the hexoses--dextrose, mannose and galactose; and the pentoses--xylose and arabinose; these less resistant cell-wall constituents are termed hemi-celluloses.

The celluloses proper are essentially non-nitrogenous, though originating in the cell protoplasm. The cell-walls of the lower cryptogams, similarly purified, retain a notable proportion--2.0-4.0%--of constitutional nitrogen. When hydrolysed these fungoid celluloses yield, in addition to monoses, glucosamine and acetic acid. The celluloses of the phanerogams are generally associated, in a degree ranging from physical mixture to chemical union, with other complicated substances, constituting the "compound celluloses." The nature of the associated groups affords a convenient classification into pecto-celluloses, ligno-celluloses and cuto-celluloses. _Pecto-celluloses_ are so named because the associated substances--carbohydrates, together with their oxidation products, i.e. containing either two carbonyls (CO) in the unit group or carboxyl (CO.OH) groups in a complex--are readily hydrolysed by weak acids to the gelatinous "pectic acids" or their salts. _Ligno-celluloses_ are the substances of lignified tissue, the non-cellulose constituents of which are characterized by the presence of benzenoid and furfuroid groups; and although essentially complex, they may be regarded as homogeneous, and are conveniently grouped under the name _lignone_. The lignone complex reacts, by its unsaturated groups, with the halogens. It is a complex containing but little hydroxyl; and is of relatively high carbon percentage (55.0-57.0%). _Cuto-celluloses_ predominate in the protective coatings of plant organs, and are characterized by constituent groups, the decomposition products of which are compounds of the fatty series, and also wax alcohols, acids, cholesterols, &c.

The typical pecto-cellulose is the flax fibre, i.e. the bast fibre of the flax plant (_Linum usitatissimum_), as it occurs in the plant, or as the commercial textile fibre in its raw state. Rhea, or ramie, is another leading textile fibre in which the cellulose occurs associated with alkali-soluble colloidal carbohydrates. Pecto-celluloses are found in the stems of the Gramineae (cereal straws, esparto), and in the fibro-vascular bundles of monocotyledons used as textile and rope-making fibres. They are the chief constituents of the fleshy parenchyma of fruits, tubers, rhizomes. Ligno-celluloses find their chemical representative in the jute fibre. They constitute the woods, and are therefore of the widest distribution and the highest industrial utility. It is important to note that a complex having all the chemical characteristics of a ligno-cellulose occurs in a soluble colloidal form in the juice of the white currant. The formation of ligno-cellulose is the chemical equivalent of the morphological change of the plant cell known as "lignification." The topical cuto-celluloses are the epidermal tissues of all growing plants or organs, which are easily detached from the underlying tissues which it is their function to protect. To subserve this function, they are extremely resistant to the attack of reagents. The associated groups are mostly of the normal saturated series, and of very high molecular weight.

_Cellulose and Botanical Science._--The elaboration of cellulose, i.e. of the cell walls, and its morphological and physiological aspects are discussed in the articles PLANTS: _Physiology, Anatomy_: and CYTOLOGY; while in the article COAL the part played by cellulose in the formation of these deposits receives treatment: here we may deal with its general relation to agriculture. In the analysis of fodder plants and other vegetable produce, the residue obtained after successive acid and alkaline hydrolysis is the "crude fibre" of the agricultural chemist, and is generally taken as a measure of the actual cellulose contents of the raw material. We give in tabular form the average percentage of crude fibre in typical food-stuffs and agricultural produce:--

SEEDS

+----------+-----------+--------------+-----------+
| Seeds of |Per cent of|Leguminous and|Per cent of|
| Cereals. | Fibre. | Oil Seeds. | Fibre. |
+----------+-----------+--------------+-----------+
| Wheat | 2.8 | Rape | 6.4 |
| Barley | 6.3 | Cotton | 7.5 |
| Oats | 9.0 | Beans | 10.0 |
| Maize | 5.2 | Peas | 10.0 |
| Rye | 8.0 | Lentils | 10.0 |
| Rice | 2.5 | Vetches | 7.2 |
+----------+-----------+--------------+-----------+

FODDER CROPS

+-----------------+---------+-----------------+-----------+---------+---------+
|Stems and Foliage|Per cent | Fodder Crops. |Per cent of| Cereal |Per cent |
| of Root Crops. |of Fibre.| | Fibre.* | Straws. |of Fibre.|
+-----------------+---------+-----------------+-----------+---------+---------+
| White Turnip | 3.9 | Grasses | 32.0 | Oats | 60.68 |
| Swedish Turnip | 4.2 | Meadow Hay | 25.8 | Wheat | 75.77 |
| Carrot | 3.1 | Clover & Trefoil| 23.5 | Barley | 71.74 |
| Mangel | 2.6 | Vetches | 25.9 | | |
| Parsnip | 2.6 | Lucerne | 26.7 | | |
| | | Sainfoin | 28.7 | | |
+-----------------+---------+-----------------+-----------+---------+---------+

+------------------+-----------+-----------+-----------+-----------+----------+
| | | | Stems and | Fodder | Cereal |
| |Leguminous.| Oil Seeds.|Foliage of | Crops. | Straws. |
| | | |Root Crops.| | |
+------------------+-----------+-----------+-----------+-----------+----------+
|Average % of water| 14 | 7 | 87 | 70-80 | 15 |
+------------------+-----------+-----------+-----------+-----------+----------+

* This percentage is calculated on airdry-produce containing 15% of
water.

The above figures have a purely empirical value, since they represent a complicated mixture of various residues derived from the celluloses and compound celluloses. This mixture may be further resolved, and by special quantitative methods the proportions of actual cellulose, ligno-cellulose and cuto-celluloses estimated (J. Konig, _Ber._, 1906, 39, p. 3564). The figures are taken as an inverse measure of digestibility; at the same time it has been established that this group of relatively indigestible food constituents are more or less digestible and assimilable as flesh and fat producers. The percentage or coefficient of digestibility of the celluloses of the more important food-stuffs--green fodder, hay, straw and grains--varies from 20 to 75%. It has also been established that their physiological efficiency is, under certain conditions, quite equal to that of starch.

It must also be borne in mind that the indigestible food residues, as finally voided by the animal, have played an important mechanical part as an aid to digestion of those constituents more readily attacked in the digestive tract of animals. They are further an important factor of the agricultural cycle. Returned to the soil as "farm-yard manure," mixed with other cellulosic matter which has served as litter, they add "fibre" to the soil and, as a mechanical diluent of the mineral soil components, maintain this in a more open condition, penetrable by the atmospheric gases, and promoting distribution of moisture. Further by breaking down, with production of "humus," a complex of colloidal "unsaturated" bodies of acid function, they fulfil important chemical functions by interaction with the mineral soil constituents.

_Chemistry of Cellulose._--Purified cotton cellulose, which is the definitive prototype of the cellulose group or series, is a complex of monoses or their "residues." It is resolved by solution in sulphuric acid and subsequent hydrolysis of the esters thus produced into dextrose. This fundamental fact with its elementary composition, most simply expressed by the formula C6H10O5, has caused it to be regarded as a polyanhydride of dextrose. Forming, as it does, simple esters in the ratio of the reacting hydroxyls 3OH: C6H10O5, and taking into account its direct converson into [omega]-brom-methyl furfural (Fenton) a constitutional formula has been proposed by A.G. Green (_Zeit. Farb. Textil Chem._ 3, pp. 97 and 309 (1904)), which is a useful generalization of its reactions, and its ultimate relations to the simpler carbohydrates, viz.,

CH(OH).CH.CH(OH)
| >O >O
CH(OH).CH.CH2 .

Green considers, moreover, that a group thus formulated may consistently represent the actual dimensions of the reacting unit, but that unit of larger dimensions, if postulated, is easily derived from the above by oxygen linkings.

From another point of view the unit group has been formulated as

/CH(OH).CH(OH)
CO >CH2
\CH(OH).CH(OH) ,

the main linking of such units in the complex taking place as between their respective CO and CH2 groups in the alternative enolic form CH-C(OH). This view gives expression to the genetic relations of the celluloses to the ligno-celluloses, to the tendency to carbon condensation as in the formation of coals, and pseudo-carbons, to the relative resistance of cellulose to hydrolysis, and its other points of differentiation from starch, and more particularly to the ketonic character of its carbonyl (CO) groups, which is also more in harmony with the experimental facts established by Fenton as to the production of methyl furfural.

The probability, however, is that no simple molecular formula adequately represents the constitution of cellulose as it actually exists or indeed reacts. On the other hand, it has been suggested that cellulose is to be regarded as representing a condition of matter analogous to that of a saline electrolyte in solution, i.e. as a complex of molecular aggregates, and of residues (of monose groups) having distinct and opposite polarities; such a complex is essentially labile and its configuration will change progressively under reaction. The exposition of this view is the subject of a publication by Cross and Bevan (_Researches on Cellulose_, ii. 1906). The main purpose is to give full effect to the colloidal characteristics of cellulose and its derivatives, with reference to the modern theory of the colloidal state as involving a particular internal equilibrium of amphoteric electrolytes.

The typical cellulose is a white fibrous substance familiar to us in the various forms of bleached cotton. Other fibrous celluloses are equally characteristic as to form and appearance, e.g. bleached flax, hemp, ramie. It is hygroscopic, absorbing 6 to 7% its weight of moisture from the air. When dry, it is an electrical insulator, and has a specific inductive capacity of about 7: when wetted it is a conductor, and manifests electrolytic phenomena.[1] It is insoluble in water and in the ordinary solvents; it dissolves, however, in a 40-50% solution of zinc chloride, and in ammoniacal solutions of copper oxide (3% CuO, 15% NH3): from these solutions it is obtained as a highly hydrated, gelatinous precipitate, from the former by dilution or addition of alcohol, from the latter by acidification; these solutions have important industrial application. Projected or drawn into a precipitating solution they may be solidified continuously to threads of various, but controlled dimensions: the regenerated cellulose, now amorphous, in its finer dimensions is known as artificial silk or lustra-cellulose. These forms of cellulose retain the general characters of the original fibrous and "natural" celluloses. In composition they differ somewhat by combination with water (of hydration), which they retain in the air-dry condition. They also further combine with an increased proportion of atmospheric moisture, viz. up to 10-11% of their weight.

_Derivatives._--Important derivatives are the esters or ethereal salts of both inorganic and organic acids, cellulose behaving as an alcohol, the highest esters indicating that it reacts as a trihydric alcohol of the formula n[C6H7O2(OH)3]. The nitrates result by the action of concentrated nitric acid, either alone or in the presence of sulphuric acid: the normal dinitrate represents a definite stage in the series of nitrates, and the ester at this point manifests the important property of solubility in various alcoholic solvents, notably ether-alcohol. Such nitrates are the basis of collodion, of artificial silk by the processes of Chardonnet and Lehner, and of celluloid or xylonite. Higher nitrates are also obtainable up to the limit of the trinitrate, which is insoluble in ether or alcohol, but is soluble in nitroglycerin, nitrobenzene and other solvents. These higher nitrates are the basis of the most important modern explosives.

Cellulose reacts directly with acetic anhydride to form low esters; in the presence of sulphuric acid the reaction proceeds to higher limits; the triacetate is soluble in chloroform. The acid sulphuric ester, C6H8O3(SO4H)2, is obtained by the action of sulphuric acid, but its relation to the original cellulose is doubtful. The monobenzoate and dibenzoate are formed by benzoyl chloride reacting on alkali-cellulose (see below). Cellulose xanthates are obtained from carbon bisulphide and alkali-cellulose; these are water soluble derivatives and the basis of "viscose," and of important industries. Mixed esters---aceto-sulphate, aceto-benzoate, nitrobenzoyl nitrates, aceto-nitro-sulphates--have also been investigated.

Cellulose (cotton), when treated with a 15-20% caustic soda solution, gives the compound C6H10O5.H2O.2NaOH, alkali-cellulose, the original riband-like form with reticulated walls of the cellulose being transformed into a smooth-walled cylinder. The structural changes in the ultimate fibre determine very considerable changes in the dimensions of fabrics so treated. The reactions and structural changes were investigated by J. Mercer, and are known generally as "mercerization." In recent years a very large industry in "mercerized" fabrics (cotton) has resulted from the observation that if the shrinkages of the yarns and fabrics be antagonized by mechanical means, a very high lustre is developed.

Similar, but less definite compounds, are formed with the oxides of lead, manganese, barium, iron, aluminium and chromium. These derivatives, which also find industrial applications in the dyeing and printing of fabrics, differ but little in appearance from the original cellulose, and are without influence on its essential characteristics.

_Decompositions._--Hydrolysis:--By solution in sulphuric acid followed by dilution and boiling the diluted solution cellulose hydrolyses to fermentable sugars; this reaction is utilized industrially in the manufacture of glucose from rags. Hydrochloric acid produces a friable mass of "hydrocellulose," probably C12H22O11, insoluble in water, but readily attacked by alkalis, with the production of soluble derivatives; some dextrose is formed in the original reaction. Hydrobromic acid in ethereal solution gives furfurane derivatives. Cold dilute acids have no perceptible action on cellulose. The actions of such acids are an important auxiliary to bleaching, dyeing and printing processes, but they require careful limitation in respect of concentration and temperature. Cellulose is extremely resistant to the action of dilute alkalis: a 1-2% solution of sodium hydrate having little action at temperatures up to 150 deg. hence the use of caustic soda, soda ash and sodium silicate in bleaching processes, i.e. for the elimination of the non-cellulose components of the raw fibres. Oxidation in acid solutions gives compounds classed as "oxycelluloses," insoluble in water, but more or less soluble in alkalis; continued oxidation gives formic, acetic and carbonic acids. Oxidation in alkaline solution is more easily controlled and limited; solutions of bleaching powder, or more generally of alkaline hydrochlorites, receive industrial application in oxidizing the coloured impurities of the fibre, or residues left after more or less severe alkali treatments, leaving the cellulose practically unaffected. This, however, is obviously a question of conditions: this group of oxidants also oxidize to oxycellulose, and under more severe conditions to acid products, e.g. oxalic and carbonic acids. Certain bacteria also induce decompositions which are resolutions into ultimate products of the lowest molecular dimensions, as hydrogen, carbon dioxide, methane, acetic acid and butyric acid (Omeliansky) (_Handb. Techn. Mykologie_ [F. Lafar] pp. 245-268), but generally the cellulose complex is extremely resistant to the organic ferments. Cellulose burns with a luminous flame to carbon dioxide and water; dry distillation gives a complicated mixture of gaseous and liquid products and a residue of charcoal or pseudo-carbon. Chromic acid in sulphuric acid solutions effects a complete oxidation, i.e. combustion to water and carbonic acid.

_Ligno-celluloses._--These compounds have many of the characteristics of the cellulose esters; they are in effect ethereal compounds of cellulose and the quinonoid lignone complex, and the combination resists hydrolysis by weak alkalis or acids. The cellulose varies in amount from 80 to 50%, and the lignone varies inversely as the degree of lignification, that is, from the lignified bast fibre of annuals, of which jute is a type, to the dense tissues of the perennial dicotyledonous woods, typified by the beech. The empirical formula of the lignone complex varies from C19H22O9 (jute) to C26H30O10 (pine wood). In certain reactions the non-cellulose or lignone constituents are selectively converted into soluble derivatives, and may be separated as such from the cellulose which is left; for example, chlorination gives products soluble in sodium sulphite solution, by the combination of unsaturated groups of the lignone with the halogen, while digestion with bisulphite solutions at elevated temperatures (140 deg.-160 deg.) gives soluble sulphonated derivatives. This last reaction is employed industrially in the preparation of cellulose for paper-making from coniferous woods. These reactions are "quantitative" since they depend upon well-defined constitutional features of the lignone complex, and the resolution of the ligno-cellulose takes place with no further change in the lignone than the synthetical combination with the substituting groups. The constituent groups of the lignone specifically reacting are of benzenoid type of the probable form

HC
//\
HC // \CO
| |
H2C \ /CO
\ /
CO ,

deduced from the similarity of the chlorinated derivatives to mairogallol, the product of the action of chlorine on pyrogallol in acetic acid solution (A. Hantzsch, _Ber._ 20, p. 2033). The complex contains methoxy (OCH3) groups. There is also present a residue which is readily broken down by oxidizing agents, and indeed by simple hydrolysis, to acetic acid. Another important group of actual constituents are pentosanes--partially isolated as "wood gum" by solution in alkalis--and furfural derivatives (hydroxy furfurals) derived from these. The actual constitutional relationships of these main groups, as well as the localization of the methoxy groups, are still problematical.

Certain colour reactions are characteristic, though they are in some cases reactions of certain constituents invariably present in the natural forms of the ligno-cellulose; which may be removed without affecting the essential character of the lignone complex. Aniline salts generally give a yellow coloration, dimethyl-para-phenylenediamine gives a deep red coloration, phloroglucin in hydrochloric acid gives a crimson coloration. Reactions more definitely characteristic of the lignone are:--ferric ferrocyanide, which is taken up and transformed into Prussian blue throughout the fibre, without affecting its structure, although there may be as much as a 50% gain in weight; iodine in potassium iodide solution gives a deep brown colour due to absorption of the halogen, a reaction which admits of quantitative application, i.e. as a measure of the proportion of ligno-cellulose in a fibrous mixture; nitric acid gives a deep orange yellow coloration; digested with the dilute acid (5-10% HNO3) at 50 deg. the ligno-celluloses are entirely resolved, the lignone complex being attacked and dissolved in the form of nitroso-ketonic acids, which, on continued heating, are finally resolved to oxalic, acetic, formic and carbonic acids.

_Derivatives of Ligno-cellulose._--By reaction with chlorine jute yields the derivative C19H18Cl4O9, soluble in alcohol, and in acetic acid; this derivative has the reactions of a quinone chloride. By reaction with sodium sulphite it is converted into a hydroquinone sulphonate of deep purple colour. The reaction of the ligno-celluloses (pine wood) with the bisulphites yields the soluble derivatives of the general formula C26H29O9.SO3H (containing two O.CH3 groups). Jute reacts with nitric acid in presence of sulphuric acid to form nitrates; and with acetic anhydride to form low acetates. It reacts with alkaline hydrates with structural changes similar to those obtained with cotton; and by the further action of benzoyl chloride and of carbon bisulphide upon the resulting compounds there result the corresponding benzoates and xanthates respectively. But these synthetical derivatives are mixtures of cellulose and lignone derivatives, and so far of merely theoretical interest.

_Decompositions of Ligno-cellulose._--In addition to the specific resolutions above described which depend upon the distinctive chemical characters of the cellulose and lignone respectively, the following may be noted: to simple hydrolytic agents the two groups are equally resistant, therefore by boiling with dilute acids or alkalis the groups are attacked _pari passu_. Weak oxidants may also be used as bleaching agents to remove coloured by-products without seriously attacking the ligno-cellulose, which is obtained in its bleached form. Nitric acid of all strengths effects complete resolution. Chromic acid in dilute solutions combines with the lignone complex, but in presence of hydrolysing acids total oxidation of the lignone is determined. The principal products are oxalic, carbonic, formic and acetic acids. This reaction is an index of constitution. Generally, the lignone is attacked under many conditions and by many reagents which are without action upon cellulose, by virtue of its unsaturated constitution, and its acid and aldehydic residues.

_Cuto-cellulose._--A typical cuto-cellulose is the cuticle (peel) of the apple which, when purified by repeated hydrolytic treatment and finally by alcohol and ether, gives a product of the composition C = 75.66%, H = 11.37%, O = 14.97%. Hydrolysis by strong alkalis gives stearo-cutic acid, C28H48O4, and oleo-cutic acid, C14H20O4 (Fremy). Cork is a complex mixture containing various compound celluloses: extraction with alcohol removes certain fatty alcohols and acids, and aromatic derivatives related to tannic acid; the residue is probably a mixture of cellulose, ligno-cellulose, cerin, C20H32O and suberin; the latter yields stearic acid, C18H36O2 and the acid C22H42O3. The cuto-celluloses have been only superficially investigated, and, with the exception of cork, are of but little direct industrial importance.

_Industrial Uses of Cellulose_.--The applications of cellulose to the necessities of human life, infinitely varied in kind as they are colossal in magnitude, depend upon two groups of qualities or properties, (1) structural, (2) chemical. The manufactures of vegetable textiles and of paper are based upon the fibrous forms of the naturally occurring celluloses, together with such structural qualities as are expressed in the terms strength, elasticity, specific gravity. As regards chemical properties, those which come into play are chiefly the negative quality of resistance to chemical change; this is obviously a primary factor of value in enabling fabrics to withstand wear and tear, contact with atmospheric oxygen and water, and such chemical treatments as laundrying; positive chemical properties are brought into play in the auxiliary processes of dyeing, printing, and the treatment and preparation in connexion with these. Staple textiles of this group are cotton, flax, hemp and jute; other fibres are used in rope-making and brush-making industries. These subjects are treated in special articles under their own headings and in the article FIBRES. The course of industrial development in the 19th century has been one of enormous expansion in use and considerable refinement in methods of preparation and manufacture. Efforts to introduce new forms of cellulose have had little result. Rhea or ramie has been a favourite subject of investigation; the industry has been introduced into England, and doubtless its development is only a question of time, as on the continent of Europe the production of rhea yarns is well established, though it is still only a relatively small trade--probably two or three tons a day total production. The paper trade has required to seek new sources of cellulose, in consequence of the enormous expansion of the uses of paper. Important phases of development were: (1) in the period of 1860 to 1870, the introduction of esparto, which has risen to a consumption of 250,000 tons a year in the United Kingdom, at which figure it remains fairly steady; (2) the decade 1870 to 1880, which saw the development of the manufacture of cellulose from coniferous woods, and this industry now furnishes a staple of world-wide consumption, though the industry is necessarily localized in countries where the coniferous woods are available in large quantities. As a development of the paper industry we must mention the manufacture of paper textiles, based upon the production of pulp yarns. Paper pulps are worked into flat strips, which are then rolled into cylindrical form, and by a final twisting process a yarn is produced sufficiently strong to be employed in weaving.

What we may call the special cellulose industries depend upon specific chemical properties of cellulose, partly intrinsic, partly belonging to the derivatives such as the esters. Thus the cellulose nitrates are the bases of our modern high explosives, as well as those now used for military purposes. Their use has been steadily developed and perfected since the middle of the 19th century. The industries in celluloid, xylonite, &c., also depend upon the nitric esters of cellulose, and the plastic state which they assume when treated with solvent liquids, such as alcohol, amyl acetate, camphor and other auxiliaries, in which state they can be readily moulded and fashioned at will. They have taken an important place as structural materials both in useful and artistic applications. The acetates of cellulose have recently been perfected, and are used in coating fine wires for electrical purposes, especially in instrument-making; this use depends upon their electrical properties of high insulation and low inductive capacity. Hydrated forms of cellulose, which result from treatment with various reagents, are the bases of the following industries: vegetable parchment results from the action of sulphuric acid upon cellulose (cotton) in the form of paper, followed by that of water, which precipitates the partially colloidalized cellulose. This industry is carried out on "continuous" machinery, the cellulose, in the form of paper, being treated in rolls. Vulcanized fibre is produced by similar processes, as for instance by treating paper with zinc chloride solvents and cementing together a number of sheets when in the colloidal hydrated state; the goods are exhaustively washed to remove, last traces of soluble electrolytes; this is necessary, as the product is used for electrical insulation. The solvent action of cupro-ammonium is used in treating cellulose goods, cotton and paper, the action being allowed to proceed sufficiently to attack the constituent fibres and convert them into colloidal cupro-ammonium compounds, which are then dried, producing a characteristic green-coloured finish of colloidal cellulose and rendering the goods impervious to water. The important industry of mercerization has been mentioned above; this is carried out on both yarns and cloth of cotton goods chiefly composed of Egyptian cottons. A high lustrous finish is produced, giving the goods very much the appearance of silk.

Of special importance are the more recent developments in the production of artificial fibres of all dimensions, by spinning or drawing the solutions of cellulose or derivatives. Three such processes are in course of evolution, (1) The first is based on the nitrates of cellulose which are dissolved in ether-alcohol, and spun through fine glass jets into air or water, the unit threads being afterwards twisted together to constitute the thread used for weaving (process of Chardonnet and Lehner). These processes were developed in the period 1883 to 1897, at which later date they had assumed serious industrial proportions. (2) The cupro-ammonium solution of cellulose is similarly employed, the solution being spun or drawn into a strong acid bath which instantly regenerates cellulose hydrate in continuous length. (3) Still more recently the "viscose" solution of cellulose, i.e. of the cellulose xanthogenic acid, has been perfected for the production of artificial silk or lustra-cellulose; the alkaline solution of the cellulose derivative being drawn either into concentrated ammonium salt solutions or into acid baths. This product, known as artificial silk, prepared by the three competing processes, was in 1908 an established textile with a total production in Europe of about 5000 tons a year, a quantity which bids fair to be very largely increased by the advent of the viscose process, which will effect a very considerable lowering in the cost of production. The viscose solution of cellulose is also used for a number of industrial effects in connexion with paper-sizing, paper-coating, textile finishes, and the production of book cloth and leather cloth, and, solidified in solid masses, is used in preparing structural solids which can be moulded, turned and fashioned.

For the special literature of cellulose treated from the general point
of view of this article, the reader may consult the following works by
C.F. Cross and E.J. Bevan: _Cellulose_ (1895, 2nd ed. 1903),
_Researches on Cellulose_, i. (1901), _Researches on Cellulose_, ii.
(1906). (C. F. C.)

FOOTNOTE:

[1] C.F. Cross and E.J. Bevan, _Jour. Chem. Soc._, 1895, 67, p. 449;
C.R. Darling, _Jour. Faraday Soc._ 1904; A. Campbell, _Trans. Roy.
Soc._ 1906.

CELSIUS, ANDERS (1701-1744), Swedish astronomer, was born at Upsala on the 27th of November 1701. He occupied the chair of astronomy in the university of his native town from 1730 to 1744, but travelled during 1732 and some subsequent years in Germany, Italy and France. At Nuremberg he published in 1733 a collection of 316 observations of the aurora borealis made by himself and others 1716-1732. In Paris he advocated the measurement of an arc of the meridian in Lapland, and took part, in 1736, in the expedition organized for the purpose by the French Academy. Six years later he described the centigrade thermometer in a paper read before the Swedish Academy of Sciences (see THERMOMETRY). His death occurred at Upsala on the 25th of April 1744. He wrote: _Nova Methodus distantiam solis a terra determinandi_ (1730); _De observationibus pro figura telluris determinanda_ (1738); besides many less important works.

See W. Ostwald's _Klassiker der exacten Wissenschaften_, No. 57
(Leipzig, 1904), where Celsius's memoir on the thermometric scale is
given in German with critical and biographical notes (p. 132); Marie,
_Histoire des sciences_, viii. 30; Poggendorff s _Biog.-literarisches
Handworterbuch_.

CELSUS (c. A.D. 178), a 2nd-century opponent of Christianity, known to us mainly through the reputation of his literary work, _The True Word_ (or _Account_; [Greek: alethes logos]), published by Origen in 248, seventy years after its composition. In that year, though the Church was under no direct threat of attack, owing to the inertia of the emperor Philip the Arabian, the atmosphere was full of conflict. The empire was celebrating the l000th anniversary of its birth, and imperial aspirations and ideas were naturally prominent. Over against the state and the worship of the Caesar stood as usual the Christian ideal of a rule and a citizenship not of this world, to which a thousand years were but as a day. A supernatural pride was blended with a natural anxiety, and it was at this juncture that Origen brought to light again a book written in the days of Marcus Aurelius, which but for the great Alexandrian might have been lost for ever. Sometimes quoting, sometimes paraphrasing, sometimes merely referring, he reproduces and replies to all Celsus's arguments. His work shows many signs of haste, but he more than compensates for this by the way in which he thus preserves a singularly interesting memorial of the 2nd century. When we remember that only about one-tenth of the _True Word_ is really lost and that about three-quarters of what we have is verbatim text, it would be ungracious to carp at the method.

The argument

Celsus opens the way for his own attack by rehearsing the taunts
levelled at the Christians by the Jews. Jesus was born in adultery and
nurtured on the wisdom of Egypt. His assertion of divine dignity is
disproved by his poverty and his miserable end. Christians have no
standing in the Old Testament prophecies, and their talk of a
resurrection that was only revealed to some of their own adherents is
foolishness. Celsus indeed says that the Jews are almost as ridiculous
as the foes they attack; the latter said the saviour from Heaven had
come, the former still looked for his coming. However, the Jews have
the advantage of being an ancient nation with an ancient faith. The
idea of an Incarnation of God is absurd; why should the human race
think itself so superior to bees, ants and elephants as to be put in
this unique relation to its maker? And why should God choose to come
to men as a Jew? The Christian idea of a special providence is
nonsense, an insult to the deity. Christians are like a council of
frogs in a marsh or a synod of worms on a dunghill, croaking and
squeaking, "For our sakes was the world created." It is much more
reasonable to believe that each part of the world has its own special
deity; prophets and supernatural messengers had forsooth appeared in
more places than one. Besides being bad philosophy based on fictitious
history, Christianity is not respectable. Celsus does not indeed
repeat the Thyestean charges so frequently brought against Christians
by their calumniators, but he says the Christian teachers who are
mainly weavers and cobblers have no power over men of education. The
qualifications for conversion are ignorance and childish timidity.
Like all quacks they gather a crowd of slaves, children, women and
idlers. "I speak bitterly about this," says Celsus, "because I feel
bitterly. When we are invited to the Mysteries the masters use another
tone. They say, 'Come to us ye who are of clean hands and pure speech,
ye who are unstained by crime, who have a good conscience towards God,
who have done justly and lived uprightly.' The Jews say, 'Come to us
ye who are sinners, ye who are fools or children, ye who are
miserable, and ye shall enter into the kingdom of Heaven.' The rogue,
the thief, the burglar, the poisoner, the spoiler of temples and
tombs, these are their proselytes. Jesus, they say, was sent to save
sinners; was he not sent to help those who have kept themselves free
from sin? They pretend that God will save the unjust man if he repents
and humbles himself. The just man who has held steady from the cradle
in the ways of virtue He will not look upon." He pours scorn upon the
exorcists--who were clearly in league with the demons themselves--and
upon the excesses of the itinerant and undisciplined "prophets" who
roam through cities and camps and commit to everlasting fire cities
and lands and their inhabitants. Above all Christians are disloyal,
and every church is an illicit collegium, an insinuation deadly at any
time, but especially so under Marcus Aurelius. Why cannot Christians
attach themselves to the great philosophic and political authorities
of the world? A properly understood worship of gods and demons is
quite compatible with a purified monotheism, and they might as well
give up the mad idea of winning the authorities over to their faith,
or of hoping to attain anything like universal agreement on divine
things.

The philosophy of Celsus

Celsus and Porphyry (q.v.) are the two early literary opponents of Christianity who have most claim to consideration, and it is worth noticing that, while they agree alike in high aims, in skilful address and in devoted toil, their religious standpoints are widely dissimilar. Porphyry is above all a pure philosopher, but also a man of deep religious feeling, whose quest and goal are the knowledge of God; Celsus, the friend of Lucian, though sometimes called Epicurean and sometimes Platonist, is not a professed philosopher at all, but a man of the world, really at heart an agnostic, like Caecilius in Minucius Felix (q.v.), whose religion is nothing more or less than the Empire. He is keen, positive, logical, combining with curious dashes of scepticism many genuine moral convictions and a good knowledge of the various national religions and mythologies whose relative value he is able to appreciate. "His manner of thought is under the overpowering influence of the eclectic Platonism of the time, and not of the doctrine of the Epicurean school. He is a man of the world, of philosophic culture, who accepts much of the influential Platonism of the time but has absorbed little of its positive religious sentiment. In his antipathy to Christianity, which appears to him barbaric and superstitious, he gives himself up to the scepticism and satire of a man of the world through which he comes in contact with Epicurean tendencies." He quotes approvingly from the _Timaeus_ of Plato: "It is a hard thing to find out the Maker and Father of this universe, and after having found him it is impossible to make him known to all." Philosophy can at best impart to the fit some notion of him which the elect soul must itself develop. The Christian on the contrary maintained that God is known to us as far as need be in Christ, and He is accessible to all. Another sharp antithesis was the problem of evil. Celsus made evil constant in amount as being the correlative of matter. Hence his scorn of the doctrine of the resurrection of the body held then in a very crude form, and his ridicule of any attempt to raise the vulgar masses from their degradation. The real root of the difficulty to Platonist as to Gnostic was his sharp antithesis of form as good and matter as evil.

Place and date.

Opinion at one time inclined to the view that the _True Word_ was written in Rome, but the evidence (wholly internal) points much more decisively to an Egyptian, and in particular an Alexandrian origin. Not only do the many intimate references to Egyptian history and customs support this position, but it is clear that the Jews of Celsus are not Western or Roman Jews, but belong to the Orient, and especially to that circle of Judaism which had received and assimilated the idea of the Logos.

The date also is clearly defined. Besides the general indication that the Empire was passing through a military crisis, which points to the long struggle waged by Marcus Aurelius against the Marcomanni and other Germanic tribes, there is a reference (_Contra Celsum_, viii. 69) to the rescript of that emperor impressing on governors and magistrates the duty of keeping a strict watch on extravagances in religion. This edict dates from 176-177, and inaugurated the persecution which lasted from that time till the death of Marcus Aurelius in 180. During these years Commodus was associated with Marcus in the imperium, and Celsus has a reference to this joint rule (viii. 71).

Value in the history of Christianity.

Celsus shows himself familiar with the story of Jewish origins. Any pagan who wished to understand and criticize Christianity intimately had to begin by learning from the Jews, and this accounts for the opening chapters of his argument. He has a good knowledge of Genesis and Exodus, refers to the stories of Jonah, Daniel (vii. 53) and Enoch (v. 52), but does not make much use of the Prophets or the Psalter. As regards the New Testament his position is closely in agreement with that reflected in the contemporary _Acts of the Martyrs of Scili_. He speaks of a Christian collection of writings, and knew and used the gospels, but was influenced less by the fourth than by the Synoptics. There is more evidence of Pauline ideas than of Pauline letters.

The gnostic sects and their writings were well known to him (viii. 15 and vi. 25), and so was the work of Marcion. There are indications, too, of an acquaintance with Justin Martyr and the Sibylline literature (vii. 53, op. v. 61). "He is perfectly aware of the internal differences between Christians, and he is familiar with the various stages of development in the history of their religion. These are cleverly employed in order to heighten the impression of its instability. He plays off the sects against the Catholic Church, the primitive age against the present, Christ against the apostles, the various revisions of the Bible against the trustworthiness of the text and so forth, though he admits that everything was not really so bad at first as it is at present."

The _True Word_ had very little influence either on the mutual relations of Church and State, or on classical literature. Echoes of it are found in Tertullian and in Minucius Felix, and then it lay forgotten until Origen gave it new life. A good deal of the neo-Platonic polemic naturally went back to Celsus, and both the ideas and phrases of the _True Word_ are found in Porphyry and Julian, though the closing of the New Testament canon in the meantime somewhat changed the method of attack for these writers.

Of more importance than these matters is the light which the book sheds on the strength of the Church about the year 180. It is of course easy to see that Celsus had no apprehension of the spiritual needs even of his own day which it was the Christian purpose to satisfy, that he could not grasp anything of the new life enjoyed by the poor in spirit, and that he underrated the significance of the Church, regarding it simply as one of a number of warring sections (mostly Gnostic), and so seeing only a mark of weakness. And yet, there is all through an undercurrent which runs hard against his surface verdicts, and here and there comes to expression. He is bound to admit that Christianity has been stated reasonably; against the moral teaching of Jesus he can only bring the lame charge of plagiarism, and with the Christian assertion that the Logos is the Son of God he completely accords. Most suggestive, however, is his closing appeal to the Christians. "Come," he says, "don't hold aloof from the common regime. Take your place by the emperor's side. Don't claim for yourselves another empire, or any special position." It is an overture for peace. "If all were to follow your example and abstain from politics, the affairs of the world would fall into the hands of wild and lawless barbarians" (viii. 68). Forced to admit that Christians are not _infructuosi in negotiis_, he wants them to be good citizens, to retain their own belief but conform to the state religion. It is an earnest and striking appeal on behalf of the Empire, which was clearly in great danger, and it shows the terms offered to the Church, as well as the strength of the Church at the time. Numerically, Christians may have formed perhaps a tenth of the population, i.e. in Alexandria there would be fifty or sixty thousand, but their power in a community was out of all proportion to their mere numbers.

LITERATURE.--Th. Keim, _Celsus' Wahres Wort_ (1873); Pelagaud, _Etude
sur Celse_ (1878); K.J. Neumann's edition in _Scriptores Graeci qui
Christianam impugnaverunt religionem_, and article in Hauck-Herzog's
_Realencyk. fur prot. Theol._, where a very full bibliography is
given. See also W. Moeller, _Hist, of the Chr. Church_, i. 169 ff.; A.
Harnack, _Expansion of Christianity_, ii. 129 ff.; J.A. Froude, _Short
Studies_, iv.

CELT, or KELT, the generic name of an ancient people, the bulk of whom inhabited the central and western parts of Europe. (For the sense of a primitive stone tool, see the separate article, later.) Much confusion has arisen from the inaccurate use of the terms "Celt" and "Celtic." It is the practice to speak of the dark-complexioned people of France, Great Britain and Ireland as "black Celts," although the ancient writers never applied the term "Celt" to any dark-complexioned person. To them great stature, fair hair, and blue or grey eyes were the characteristics of the Celt. The philologists have added to the confusion by classing as "Celtic" the speeches of the dark-complexioned races of the west of Scotland and the west of Ireland. But, though usage has made it convenient in this work to employ the term, "Celtic" cannot be properly applied to what is really "Gaelic."

The ancient writers regarded as homogeneous all the fair-haired peoples dwelling north of the Alps, the Greeks terming them all _Keltoi_. Physically they fall into two loosely-divided groups, which shade off into each other. The first of these is restricted to north-western Europe, having its chief seat in Scandinavia. It is distinguished by a long head, a long face, a narrow aquiline nose, blue eyes, very light hair and great stature. Those are the peoples usually termed Teutonic by modern writers. The other group is marked by a round head, a broad face, a nose often rather broad and heavy, hazel-grey eyes, light chestnut hair; they are thick-set and of medium height. This race is often termed "Celtic" or "Alpine" from the fact of its occurrence all along the great mountain chain from south-west France, in Savoy, in Switzerland, the Po valley and Tirol, as well as in Auvergne, Brittany, Normandy, Burgundy, the Ardennes and the Vosges. It thus stands midway not only geographically but also in physical features between the "Teutonic" type of Scandinavian and the so-called "Mediterranean race" with its long head, long face, its rather broad nose, dark brown or black hair, dark eyes, and slender form of medium height. The "Alpine race" is commonly supposed to be Mongoloid in origin and to have come from Asia, the home of round-skulled races. But it is far more probable that they are the same in origin as the dark race south of them and the tall fair race north of them, and that the broadness of their skulls is simply due to their having been long domiciled in mountainous regions. Thus the "Celtic" ox (_Bos longifrons_), from remote ages the common type in the Alpine regions, is characterized by the height of its forehead above the orbits, by its highly-developed occipital region, and its small horns. Not only do animals change their physical characteristics in new environment, but modern peoples when settled in new surroundings for even one or two centuries, e.g. the American of New England and the Boer of South Africa, prove that man is no less readily affected by his surroundings.

The northern race has ever kept pressing down on the broad-skulled, brown-complexioned men of the Alps, and intermixing with them, and at times has swept right over the great mountain chain into the tempting regions of the south, producing such races as the Celto-Ligyes, Celtiberians, Celtillyrians, Celto-Thracians and Celto-Scythians. In its turn the Alpine race has pressed down upon their darker and less warlike kindred of the south, either driven down before the tall sons of the north or swelling the hosts of the latter as they swept down south.

As the natives of the southern peninsula came into contact with these mixed people, who though differing in the shape of the skull nevertheless varied little from each other in speech and colour of their hair and eyes, the ancient writers termed them all "Keltoi." But as the most dreaded of these Celtic tribes came down from the shores of the Baltic and Northern Ocean, the ancients applied the name Celt to those peoples who are spoken of as Teutonic in modern parlance. The Teutons, whose name is generic for Germans, appear in history along with the Cimbri, universally held to be Celts, but coming from the same region as the Guttones (Goths) by the shores of the Baltic and North Sea. Again, the Germani themselves first appear in the Celtic host destroyed by Marcellus at Clastidium in 225 B.C. All the true Celtae or Galatae in France had come across the Rhine; the Belgic tribes in northern France were Cimbri, who also had crossed the Rhine: in Caesar's day the Germans were still constantly crossing that river, and so-called Gauls who lived near the Germans, e.g. the Treveri, closely resembled the latter in their habits, while in later times were to come Goths and Franks from beyond the great river. It is then not strange that the Gallic name for a henchman (_ambactus_) is the same as the Gothic (_ambahts_).