We now leave the physiological class and take up those tanning materials included in the pathological class, or those of abnormal growth.


These are not consumed to any great extent at the present period, but formerly they were used quite extensively. The galls are found upon the leaves of the oak or sumac, etc. The direct cause of their growth is that a certain wasp (cynips galles) stings into the leaf and after depositing its egg, flies away. The egg develops into a larva and then into a full-fledged wasp, boring its way out of the gall which has served as a protection and nourisher. This accounts for the hole noticed in almost every gall. The different varieties include Aleppo. It is found upon the same trees as the valonia and contains 60 to 75 per cent. tannin; Istrian galls, 32 per cent. tannin; Persian, 28 to 29 per cent. tannin. Chinese galls, giving 80 to 82 per cent. tannin, are the results of the sting of a louse, and make a very light-colored leather. The dyers also use this material for coloring.

Knoppern - Belongs to the family of galls, and is a most important factor of commerce in Austria. The knopper is generally found on the acorn or leaf of the oak tree. The greatest quantity is derived from the steel oak of Hungary. The tannin contained varies from 27 to 33 per cent. Knoppern are not being used so much now as formerly, and consequently the amount harvested lessens from year to year. Its main use was and is in combination with valonia as layers for sole leather. Valonia gives better weight results than knoppern, and is replacing knoppern more and more every year. The combination of knoppern, valonia and myrabolams is also quite popular, and gives good results. Knoppern are seldom used alone, being generally combined with some other tannin. Austria is almost the only consumer at present, but Germany used it extensively formerly.

Bark and Wood Extracts - Are becoming general favorites throughout Europe, partly because of their weight-giving qualities and partly as the transportation costs so little; they can be used to strengthen weak bark liquors.

Oak Extracts - Are well liked, both wood and bark, and are used extensively. Slavonia furnishes a great deal of it.

Chestnut Oak Wood Extract - Is manufactured in quantities, and easily finds purchasers.

Pine Bark Extract - Is also consumed in goodly amounts.

Quebracho Wood Extract

The wood is shipped from Brazil to Hamburg and other ports, and the tannin extracted there. Hamburg furnishes quantities of it.

Hemlock Extract - Is used in Russia, and seems to have taken a hold on the shoe buyers' fancies, as they now make imitations of it in color. The hemlock that is consumed is imported from America.

As most leather is sold by weight in Europe, the leather manufacturers aim to obtain as good weight results as possible, and often, I am sorry to say, do so at the sacrifice of quality. This is common to both upper and sole leather. Sole leather is nine times out of ten given false weight by forcing entirely foreign substances into the leather, such as glucose, barium chloride, magnesium chloride, resins, etc. Glucose and resin are also used for weighting upper leather. Leather is also weighted with extracts by overtanning. Leather buyers have become very wary of late and do not purchase large quantities before an analysis is made of a fair sample.

One more word before I close. The governments and private individuals in Europe cultivate and raise trees for both lumber and bark purposes. The forests are excellently cared for by efficient foresters, and the result is that the tanners obtain much cleaner and better bark, and of a very even quality. Would it not be a good idea if some individual, who would certainly earn the everlasting gratefulness of the tanners, would look into this matter, and see that not only the lumber side of our forest cultivation is not neglected, but that the bark also is preserved and cared for? Of course, we can obtain all the bark necessary at present and for some time to come, but the time will come when we shall certainly regret not having taken these steps, if the lumbermen and bark peelers go on devastating magnificent forests. Below will be found a table of weight results. Sole leather tanned with these materials gives for every 100 lb. green hide the following quantities of finished leather:

Oak bark48 to 54
Oak extract55 to 56
Pine bark 44 to 46
Pine extract 48 to 50
Willow 45 to 46
Birch bark and oak extract49 to 51
Quebracho wood and extract 48 to 49
Valonia 52 to 56
Knoppern 51 to 53
Myrabolams 50
Knoppern, myrabolams and valonia52 to 53

Specification of tanning materials used in different countries:

 France. Oak bark (kirmess).


Chestnut wood extract.

Quebracho " "

Some gambier. Italy. Oak bark.

Pine "


Valonia. England. Oak bark.

Divi divi.




Extracts { Oak bark and wood hemlock.


Cutch. Germany and Austria. Oak bark.

Pine "

Willow bark.




{ Oak bark and wood.

Extracts { Pine bark and wood. Russia. Birch bark.

Willow "

Oak "

Pine "

Hemlock extract. Norway and Sweden. Birch bark.

Willow "

Oak " 

- Shoe and Leather Reporter.[1] In the principal districts in America, removed from the cities, the price of oak bark is about $4 to $6 per cord or per ton of 2,240 lb. The hemlock bark, which gives a sole leather just as thoroughly tanned, but of a darker and reddish color, costs the larger tanners from $3 to $4 a cord.