Volume 1
Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors.
- Date:
- 1888-1894
Licence: Public Domain Mark
Credit: Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
744/796 (page 718)
![the addition of the oxide in the proportion ZnO:2Na„0. He also found that the actions were favoured by low temperatures (v. Life of John Mercer by E. A. Parnell, London, 1886). By these characteristics the hydration phe- nomena in question are seen to be closely related to those attending the action of the Schweitzer reagent (supra). The more powerful action of the latter we must refer either to the specific action of the ammonia upon the con- densed aldehydic molecules of which cellulose appears to be constituted, or to the particular relationship of the molecular weight of the cuprammonia in solution to that of the cellu- lose or cellulose hydrate which it forms. The action of concentrated solutions of zinc chloride is similar to that of the alkaline hy- drates above hydrates. It is remarkable on the other hand that a saturated solution of zinc nitrate is without action (Mercer). (3) Water.—Heated in contact with water, cellulose is attacked at 160°, but not below 150° (Scheurer a. Grosseteste, Bull. Mulhouse, 1883, 62-85). Heated at 200° in contact with water in sealed glass tubes it is fundamentally re- solved, being converted into highly-coloured products, insoluble for the most part, with a small proportion of soluble derivatives amongst which are furfural and pyrocatechol (Hoppe- Seyler, B. 4,15). (4) Ferments.—There are, it can scarcely be doubted, endless transformations of cellulose determined by the so-called soluble ferments, though but few have been investigated. The soluble ferment of the foxglove is stated to con- vert cellulose into glucose and dextrin (Kos- mann, Bl. [2] 27, 246). The fluid from the ver- miform appendix of the rabbit has also been found to digest cellulose with liberation of marsh gas and formation of a soluble compound which reduces cupric oxide in alkaline solution. Proximate Syntheses of Cellulose.—Trans- formations of the soluble carbohydrates into cel- lulose, which we may regard as a proximate synthesis of this body, are, as already stated, an important feature in the life of plants. The mechanism of these changes has been thus far but slightly studied, and they are of a kind to elude chemical investigation. Of those which have been studied we may notice (a) There is a changesetup ' spontaneously' in beet juice which resultsinthe formation of a hard white substance, having the properties of cellulose. On trans- ferring these lumps to a solution of pure cane sugar, a further transformation of the saccharose into the same substance is brought about. At the same time there is produced a gummy sub- stance which is ppd. by alcohol as a white caou- tchouc-like substance of the same composition as cellulose but swelling up with water and other- wise differing in its physical properties from cellulose. This latter derivative is also formed by the action of diastase upon a solution of saccharose. A similar transformation takes place under the influence of certain fatty seeds, e.g. those of rape and colza, and it is probable that the formation of cellulose from saccharose in the plant takes place under the influence of ferments similar to those above described (Durin, C. R. 82, 1108). (b) More recently A. Brown has investigated the formation of cellulose by the ' vinegar-plant,' growing in solutions of the carbohydrates, e.g. dextrose in yeast-water. The cells elaborate an extra-cellular film, which acts as a ' cell-collect- ing medium,' and they possess, therefore, a two- sided activity, i.e. the property above mentioned, in addition to their strictly fermentative activity. The cellulosic film in question was found to contain 50-60 p.c. pure cellulose. It is note- worthy that in a solution of levulose the growth of the ' plant' is unattended by fermentative action, 33 p.c. of the substance being on the other hand transformed into cellulose (C. J. 48, 432). Other Foems op Cellulose. We cannot attempt to enumerate the multi- tudinous varieties of cellulose which the plant world presents. Some of these, when isolated in the pure state, resemble the typical cellulose above described, e.g. the cellulose of hemp and rhea. Others, especially such as require a drastic process of resolution, e.g. the cellulose isolated from jute and wood by the chlorination method (infra), resemble rather the (a)-oxycelluloses. Thus jute cellulose (3CBH10O5.H2O) reduces cupric oxide in alkaline solution, and is much more susceptible of degradation by hydrolytic reagents than those of the cotton type. Cellu- lose from pinewood is similar in composition and properties. Cellulose from esparto and straw, isolated by treatment of the plant substance with alkaline solutions boiling under pressure—which are amongst the most important of the staple ma- terials of the paper-maker — are distinguished by their reaction with aniline salts, being coloured a deep pink on boiling with solutions of these compounds. Many of the celluloses are decom- posed on boiling with dilute acids with formation of furfural and formic acid: hay cellulose yields under certain conditions a volatile crystalline body, which appears to be a furfural derivative, but is still under investigation. It may be mentioned here that the term cellu- lose is applied by plant physiologists and agri- cultural chemists to substances which would not come under the definition, upon which this article is based, of cellulose as the (white) in- soluble residue which survives the exhaustive treatment of plant substances alternately with chlorine, bromine, or oxidising agents, and boil- ing alkaline solutions. Animal cellulose.—The mantles of the Pyro- somidfe, Salpidse, and Phallusia mammilaris, freed from chondrigen by boiling in a Papin's digester and further purified by prolonged boiling with potash solution, yields a residual substance which not only has the ultimate composition of cellulose, but has identical properties, e.g. dis- solves in cuprammonia, is converted by nitric acid into an explosive nitrate soluble in ether (Schafer, A. 160, 312). According to Virchow cellulose is found in degenerated human spleen and in certain parts of the brain (C. R. 37, 492, 860). Compound Celluloses. Plant tissues, always containing a propor- tion of cellulose more or less large, frequently con- tain other constituents so intimately united to](https://iiif.wellcomecollection.org/image/b21995990_0001_0744.jp2/full/800%2C/0/default.jpg)
