Tannin Solutizer treating

Sugars may be tested for with Fehling s solution in the tannin solution treated with lead acetate and then with sodium sulphate and subsequently inverted. Since, however, tanning materials generally contain a certain quantity of reducing sugars, addition of glucose cannot always be proved by a mere qualitative test,... 

Figure 19.4 shows the SEM micrographs of the mst surfaces before and after immersion in the mangrove tannin solution at pH 4.0. The pre-rusted sample shows basically coral-like stractures distributed in a random matmer. This stracture disappeared with the tannin treated samples and was replaced by a coarse layer with cracks of irregular shapes. A closer inspection of the surface of each crack revealed tiny flowered-like stmctures stacked on top of one another. Unconverted mst stmctures were observed underneath the transformed tannins. 

One hundred milliliters of a 0.001% solution of tetrachloroauric (III) acid (or silver nitrate) in distilled water ia treated with several drops of 1% sodium carbonate 10-hydrate and heated to boiling in a flask. Every 30 seconds one drop of a fresh 1% tannin solution (XJ.S.P.) is added with agitation. When a deep red gold color has formed (or yellow-brown to red-brown for the silver) the colloidal solution is cooled and stabilized by the addition of a few milliliters of chloroform or toluene. 

Stannous tannin solution is treated with 10 c.c, of a concentrated solution of stannous chloride in... 

Internal use is in the treatment of catarrh of the stomach and as an antidiarrheal. Not all tannins are suitable for all uses. In the treatment of large burns, tannins are absorbed in such large quantities that they can cause serious damage to the liver. That is the reason why large burns are not treated with tannin solution any more. 

Alternate methods a) A O.OOIN AgNOa solution (100 ml.) is treated with a few drops of freshly prepared tannin solution and one drop of 1% sodium carbonate solution. Heating the mixture results in formation of a sol (W. Ostwald, Kleines Praktikum der Kolloidchemie [Lab. Manual for Colloid Chem.], 7thed., 1930, p. 4). 

M.-E. Chevreul, near the beginning of his surprisingly long career, studied Hatchett s papers and prepared some of the tannin. Hatchett had found that pit coal which contained no resinous substance was dissolved completely by nitric acid and converted into the artificial tannin, whereas any resinous matter remained undissolved. When Chevreul treated pit coal with nitric acid, however, evaporated the solution, and poured it into water, a yellow matter separated, which was much more abundant than what remained in solution, and had no property that rendered it similar to resins. . . yet I do not allow myself, said Chevreul, the least reflection on the labours of that celebrated English chemist, as I am too fully aware that different modes of operating and the different varieties of the bodies examined. . . may produce a variation in the results.. . Chevreul found that the water-soluble substance which precipitated gelatine copiously was a compound of nitric acid and carbonaceous matter. . (22). These artificial tannins... 

The presence of sulphite cellulosic liquors may be recognised, according to Procter and Hirst, by treating 5 c.c. of the dilute solution (which is used for analysis) with 0-5 gram of aniline and then, after shaking, with 2 c.c. of concentrated hydrochloric acid in presence of such liquors a precipitate is immediately formed and gradually rises to the surface. A more certain indication of the addition of sulphite cellulose liquors may, however, be obtained from a comparison of the results of the determination of the tannin by two methods—indirect and direct (see later). 

About 6o c.c. are then collected separately in a flask this should be colourless, or almost so, and a few drops of it, treated with a solution of gelatine and sodium chloride (or with some of the initial distillate, which contains a small quantity of gelatinous substances and is a good reagent for the detection of tannin), gives no turbidity. 

Further, an aqueous solution of the colouring matter may be treated with basic lead acetate (a basic colouring matter should first be precipitated with tannin), the excess of lead eliminated, the liquid filtered and the sugars tested for or determined saccharimetrically or with Fehling s solution. 

The procedure for this test consists basically of three sequential treatments of the lignified tissue with 1% potassium permanganate, 3% hydrochloric acid (Note 1), and concentrated ammonium hydroxide. A small amount of wood meal or wood slices is placed on a watchglass or microscope slide and immersed in a 1% potassium permanganate solution for 5 min at room temperature. The solution is discarded and the sample is washed twice with water and then treated with a 3% hydrochloric acid solution until the color turns from black or dark brown to light brown. If necessary, additional hydrochloric acid may be added to facilitate discharge of the dark color. The hydrochloric acid solution is discarded, and the sample is washed twice with water. On subsequent treatment with concentrated ammonium hydroxide, a red-purple color develops for hardwoods and some tannins, and a brown color for softwoods. 

Tannin test When a neutral or acetic acid solution of a vanadate is treated with an excess of 5 per cent tannic acid, a deep blue (or blue-black) colouration is obtained. If ammonium acetate is present, a dark-blue (or blue-black) precipitate separates. The precipitate or colouration is destroyed by mineral acids. 

Hydrolysed, polynuclear Cr complexes are of considerable commercial importance in the dying and tanning industries. In the former the role is that of a mordant to the dye. In leather production it is necessai to treat animat hides to prevent putrefaction and to render them supple when dry. Traditionally, tannin was used, hence the name of the process, but this was superseded towards the end of the nineteenth century by solutions of chromium(lil) sulfate. After soaking in sulfuric acid the hides are impregnated with the Cr solution. This is subsequently made alkaline, when the polynuclear complexes form and bridge... 

Thus, if diluted alcohol ue poured over powder of mynh, in tho cylinder of the percolator, the fluid which first drops into tho receiver is a solution of an oily consistence chiefly composed of resin and volatile oil dissolved in alcohol. In like manner when the powder of gall-nuts is treated in the some way by hydrated sulphuric other, two layeVe of fluid aro obtained, one of which is a highly concentrated solution of tannin in the water of tho ether, and the other a weak solution of the same principlo in pure ether. In all cases, therefore, in which it is not otherwise directed, it is absolutely necessary to agitate the several portions of the liquid obtain by... 

To remove tannins the solution is treated with 0.5 g basic lead acetate, vigorously shaken and then filtered. To remove interfering resins and lipids, the powdered drug can be extracted under reflux for about 15 min with liglit petroleum before extraction with methanol. 

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