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The great number of compounds and derivatives, i.e., substances obtained by chemical treatment, may be judged from the following list. The substances of commercial importance are suitably distinguished from those of merely scientific interest by the printing of the names in small capitals.

Acetic Acid.—An important commercial product obtained by the destructive distillation of wood. The crude pyroligneous acid is first neutralised with chalk or lime, and the calcium acetate formed then distilled with sulphuric acid. Wood yields 5 to 10 per cent. of its weight of acetic acid according to the nature of the wood.

Acetone.—A solvent for resins, gums, camphor, gun cotton, and other cellulose products. Prepared by distilling barium or calcium acetate in iron stills, the acetate being obtained from the crude acetic acid produced by the dry distillation of wood.

Acid Cellulose.—(See Hydral-Cellulose.)

Adipo-Cellulose.—A distinct compound cellulose present in the complex cuticular tissue of plants, and separated easily by suitable solvents from the wax and oily constituents also present.

Alkali Cellulose.—When cotton pulp is intimately mixed with strong caustic soda solution, this compound is formed. It is utilised in the manufacture of Viscose.

Amyloid.—Strong sulphuric acid acts upon cellulose and converts it into a gelatinous semi-transparent substance to which the name amyloid has been given. (See Parchment Paper.)

Ballistite.—A smokeless powder composed of nearly equal parts of nitro-glycerine and nitrated cellulose, with a small quantity of diphenylamine.

Carbohydrate.—A large number of important commercial products, such as cellulose, sugars, starches, and gums, consist of the elements carbon, hydrogen, and oxygen, associated in varying proportions. The ratio of hydrogen to oxygen in these compounds is always 2:1 (H₂ and O).

Cellulose	C6H10O5.
Sugar	C6H12O6.
Dextrin n	(C6H10O5).

To all these substances the term carbohydrate is applied.

Celloxin (Tollens).—A substance having the stated composition C₈H₆O₆ considered to be present in oxidised derivatives of cellulose.

Celluloid.—This well-known material is made by incorporating camphor with nitro-cellulose, a plastic ivory-like substance being produced. In practice the process is as follows:—Wood pulp or wood pulp paper is saturated with a mixture of sulphuric acid (five parts) and nitric acid (two parts), which produces nitrated cellulose. The product is washed, ground, and mixed with camphor, the mastication being effected by heavy iron rollers. The mass thickens and can be removed in the form of thick sheets. These sheets are submitted to great pressure between steam-heated plates. The cake obtained is cut into sheets of any desired thickness, seasoned by prolonged storage, and afterwards worked up into boxes, combs, brush-backs, and many other domestic articles of a useful and ornamental character.

Cellulose Acetate (Cross).—If cellulose is heated with acetic anhydride at 180° C., viscous solutions of the acetates are obtained. The process yielding a definite acetate of commercial value is based upon the following reaction:—100 parts of cellulose prepared from the sulpho-carbonate are mixed with 120 parts of zinc acetate, heated and dried at 105° C. Acetic anhydride is added in small quantity, and 100 parts of acetyl chloride. At a temperature of 50° C. the mixture becomes liquid, and cellulose acetate is subsequently obtained as a white powder.

The compound can be used in the place of cellulose nitrate, and, being non-explosive, may gradually replace the latter in many industrial applications.

Cellulose-Benzoate.—When alkali cellulose is heated with benzoyl chloride and excess of caustic soda, this substance is obtained.

Cellulose Hydrate.—The substances produced by the action of acid and alkali on cellulose under certain strictly defined conditions are bodies containing cellulose united with water to form hydrates. The industrial applications of cellulose based upon this reaction are described under the special headings.

Cellulose Nitrate.—A considerable number of derivatives are obtained by bringing cellulose into contact with nitric acid. Variations in the strength of the acid, the temperature of reaction, and the time of contact determine the nature of the product. The best known nitrates are:—

Cellulose di-nitrate.

Cellulose tri-nitrate and tetra-nitrate, present chiefly in pyroxyline.

Cellulose penta-nitrate.

Cellulose hexa-nitrate, the chief constituent of gun-cotton.

Charcoal.—Not a cellulose derivative in the strict sense of the term, charcoal being a residue obtained in the dry distillation of wood.

Collodion.—A soluble nitrate of cellulose used in photography. (See Pyroxyline.)

Cordite.—A smokeless powder consisting mainly of nitro-glycerine and gun-cotton mixed with acetone. The materials are thoroughly incorporated and the resultant paste formed into threads which are dyed and then cut up into suitable lengths for cartridges.

Cuto-Cellulose.—Synonymous with adipo-cellulose.

Dextron.—A compound prepared from the waste liquors of the bisulphite process used for the manufacture of wood pulp. Resembles dextrin in its physical properties.

Dextrose.—A carbohydrate which can be obtained by the action of mineral acids on cellulose. Commercial dextrose, or glucose, is prepared by the conversion of starch with sulphuric acid. The starch is mixed with dilute acid at a fixed temperature, and the starch milk obtained poured gradually into a vessel containing dilute acid, which is maintained at boiling point. The conversion is complete and rapid.

Explosives.—The production of the several cellulose nitrates has given rise to a great number of highly explosive substances.

Blasting Gelatine.—A mixture of nitro-glycerine with cellulose nitrates.

Amberite, Ballistite, Cordite, and other smokeless powders, consisting of nitro-glycerine and cellulose nitrates in about equal proportions.

Sporting powders made by mixing nitro-cellulose with barium nitrate, camphor nitro-benzene, such as indurite, plastomenite, etc.

Glucose.—(See Dextrose.)

Gun-cotton.—An explosive prepared by the action of nitric acid on cotton. Selected cotton waste suitably opened up is immersed in a mixture of three parts of nitric acid by weight (1·50 sp. gr.) and one part of sulphuric acid by weight (1·85 sp. gr.) and submitted to a number of processes by which the nitration is properly effected so as to produce a nitro-cellulose of uniform composition. The material is washed, reduced to pulp, and moulded into various forms.

Hemi-Cellulose.—The constituents of plant tissues are extremely varied in character. Many plants contain substances which resemble true cellulose, but differing from it in being easily converted by hydrolysis, and by the action of dilute acids, into carbohydrates. Plants which contain a large proportion of such constituents are termed hemi-celluloses. In some cases certain crystallisable sugars can be obtained by hydrolysis under suitable conditions.

Hydral-Cellulose (Bumcke).—A compound of merely scientific interest, resulting from the treatment of cellulose with hydrogen peroxide. When acted upon by alkali it is decomposed into cellulose and acid cellulose, the latter a derivative of unstable composition.

Hydro-Cellulose.—This product, a white, non-structureless, friable powder, is obtained by treating cellulose with hydrochloric or sulphuric acid of moderate strength. The substance itself has no commercial value, but the reaction is useful in separating cotton from animal fabrics. If a woollen cloth containing cotton is soaked in dilute sulphuric acid, washed, and dried at a gentle heat, the cotton is acted upon, and can be beaten out of the fabric, the wool resisting the acid treatment.

Lignin.—The complex mixture of substances which is associated with cellulose in wood, jute, and other ligno-celluloses. The conversion of wood into chemical pulp effects the removal of this material more or less completely. The well-known “phloroglucine” test for mechanical wood in papers is based upon the presence of lignin in the wood.

Ligno-Cellulose.—Wood and jute are typical bodies consisting of cellulose and complex non-cellulose, generally described as lignin, associated together in the plant tissue. The chemistry of the non-cellulose portion of wood is a matter still under investigation, its importance from a commercial point of view being obvious from the fact that the removal of the lignin during the conversion of the wood into wood-cellulose results in a loss of 50 per cent. of the weight of wood.

Lustra-Cellulose.—Synonymous with and suggested as a more appropriate name for the material usually described as artificial silk.

Mercerised Cotton.—When cotton is immersed in strong solutions of caustic soda a remarkable change sets in. The physical structure of the fibre is entirely altered from the long flattened tube having a large central canal to a shorter cylindrical tube in which the canal almost disappears. Hydration of the cellulose takes place, and these changes are taken advantage of in the production of mercerised cloth (so named from the discoverer of the reaction, Mercer). Cotton goods, particularly those made of long stapled cotton, when mercerised, exhibit a beautiful lustre, and some magnificent crêpon effects are obtained by the process.

Methoxyl.—A constituent of the complex compound known as ligno-cellulose, which is present in wood and similar fibres. The amount of methoxyl in lignified tissue can be accurately determined, and it has been suggested that the proportion of methoxyl found in a cheap printing paper could be used as a measure of mechanical wood pulp present.

Muco-Cellulose.—This term is applied to certain compound celluloses present chiefly in mucilages, gums, and in seaweeds (Algæ). The natural substances are all of commercial importance—Iceland moss, Carragheen, Algin, etc.

Naphtha.—One of the products of the dry distillation of wood, usually described as wood-naphtha, or wood spirit.

Nitro-Cellulose.—The treatment of cellulose with nitric acid gives a number of nitro-celluloses according to the conditions of the process. (See Cellulose Nitrates.)

Oxalic Acid.—A substance of great commercial importance prepared by heating the sawdust of soft wood, such as pine, fir, and poplar, with strong solutions of mixed caustic soda and potash to dryness. The wood yields after six hours a greyish mass containing about 20 per cent. of the acid, which is separated out by water and then crystallised.

It is used for bleaching, and as a discharge in calico printing and dyeing.

Oxy-Cellulose.—A white friable powder produced by treating cellulose with nitric acid at 100° C. The oxidation of cellulose is brought about by several reagents such as chromic acid, hypochlorites of lime and soda, chlorine, and permanganates. The extent to which cloth has been damaged by overbleaching may be determined by a simple test with methylene blue solution, which is readily absorbed by oxy-cellulose present in such fabrics.

Parchment.—A tough paper prepared by the action of sulphuric acid on unsized paper. (See page 137.)

Pectins.—(See Pecto-Cellulose.)

Pecto-Cellulose.—A generic term applied to many important fibrous materials, such as flax, straw, esparto, bamboo, phormium, ramie, &c., which on alkaline treatment yield cellulose for paper-making, and a non-fibrous soluble residue of complex composition. These soluble derivatives are known as pectin (C₃₂H₄₈O₃₂), pectic acid (C₃₂H₄₄O₃₀), and metapectic acid (C₃₂H₂₈O₃₆). Although the soluble constituents of the pecto-celluloses amount to 50 per cent. by weight in most cases, no process for the recovery of the product in a commercial form has yet been devised. (See description of Soda recovery, page 78.)

Pyroxyline.—A substance prepared by nitrating cotton. The cotton is immersed in a mixture of nitric and sulphuric acids of carefully regulated strength, and subsequently washed free of the acid. Three volumes of nitric acid (sp. gr. 1·429) are diluted with two volumes of water and nine volumes of strong sulphuric acid (sp. gr. 1·839) added. To the solution when cool the cotton is added in small quantities at a time. The resultant pyroxyline is soluble in a mixture of equal quantities of alcohol and ether, and in the soluble form is utilised as collodion for photography.

Silk, Artificial.—A remarkable substance made from wood or cotton cellulose, closely resembling silk in appearance and physical properties.

Nitrated cellulose is dissolved in a mixture of equal parts of alcohol and ether.

The solution is forced through five capillary tubes under high pressure, and the filament so obtained solidifying at once is wound together with other similar filaments upon suitable bobbins. Various modifications of this general process are in use, such as the solidification of the solution into threads by passing it into water; the application of solvents less inflammable than ether and alcohol; the use of other forms of dissolved cellulose such as those prepared by means of zinc chloride, ammoniacal copper oxide, or acetic anhydride. In all cases the yarn or thread is submitted to further chemical treatment for the removal of nitric acid and to render the material non-explosive and less inflammable. The finished product is soft and supple, can be easily bleached and dyed, and is capable of acquiring a high lustre.

Smokeless Powders.—(See Explosives.)

Sulpho-Carbonate.—(See Viscose.)

Sulphate Cellulose.—Chemical wood pulp prepared by the sulphate process. (See page 107.)

Sulphite Cellulose.—Chemical wood pulp prepared by the sulphite process. (See page 107.)

Viscose.—A soluble sulpho-carbonate of cellulose, prepared by treating cellulose with a 15 per cent. solution of caustic soda, and shaking the product with carbon bisulphide in a closed vessel. The mixture forms a yellowish mass soluble in water, giving a viscous solution which has some remarkable and valuable properties.

This viscose, on standing, coagulates to a hard mass which can be turned and polished.

If spread on glass and coagulated by heat, films are obtained from which the alkaline by-products can be washed out. These films are transparent, colourless, very tough and hard.

Vulcanised Fibre.—Fibre or pulp treated with zinc chloride in acid solution, or otherwise, for the manufacture of hard boards. (See page 139.)

Willesden Goods.—Paper, fibre, and textiles when treated with cuprammonium oxide are partially gelatinised on the surface and rendered waterproof. (See page 139.)

Wood Spirit.—(See Naphtha.)

Xylonite.—(See Celluloid.)