=Methods of Use.=--The synthetic tanning materials may be put to many uses. When well manufactured they make practically a white leather, and this fact makes a valuable opening for their use in connection with light leather tannages and the dressing of rugs. It is also claimed that they improve the colour usually obtained in the ordinary vegetable tannages. If used in the suspenders to the extent of 5-10 per cent. they are said to brighten the colour throughout the tannage. If used in bleaching and finishing they are said to lighten the colour of the finished leather. About 5 per cent. on the weight of the goods may be added to the bleach or vat liquors; they may be also mixed with sumac during finishing, and in effect act as a sumac substitute; solutions are also brushed over the grain before oiling, with a view to obtaining good colour. It is also claimed that their use prevents vegetable-tanned leather from becoming red under the action of sunlight. The syntans are also used to lighten the colour of chrome leather, even of chrome sole leather after it has been dipped. It is claimed also that syntans produce a tough leather, and if used for heavy leather in the early stages they give a tough grain and assist in avoiding a cracky grain. On this account they are also recommended for retanning E.I. tanned kips. When used in heavy leather suspenders they are said to get rid of lime blast (CaCO{3}) and to quicken the tannage, _i.e._ to enable the same weight to be obtained in less time. Procter suggests that a tannage of commercial value might be obtained by blending them with wood pulp extract. If used alone for tanning a series of pits containing liquors of 4° to 37° Bkr. may be used, but drum tannages may be given using liquors of 14°-29° Bkr., the goods being tanned in 6-8 hours. About 30 per cent. of syntans are said to be necessary for complete tannage. REFERENCES. E. Stiasny, "A New Synthetic Tannin," _Collegium_, 1913, 142-145. (See also _J.S.C.I._, Abs. 1913, 500.) E. Stiasny, "Syntans--New Artificial Tanning Materials," _J.S.C.I._, 1913, 775. Patents:--Austrian 58,405. German 262,558, Sept. 12, 1911. French 451,875, Dec. 13, 1912; 451,876, Dec. 13, 1912; 451,877, Dec. 13, 1912. SECTION VI.--COMBINATION TANNAGES