Scientific American 14, 3.4.1869
A process has been invited in England for preparing hides to receive more readily the action of tannin. After the hair and particles of flesh have been removed, and the hides have been properly cleaned by the action of lime, the first step in this new process is to place the hides in water sufficient to cover them. The hides are to be placed in separately, with the fleshy side upwards, and are to be sprinkled with bran in the following proportions:
Light hides, for uppers, etc., each skin 6 ounces
Calf skins 8 "
Sheep skins 4½ "
Heavy hides, for sole leather 14 "
In this vat the skins must remain until fermentation has taken place, which will be, in warm weather, in about two days, but in cold weather somewhat longer. After this the skins must be removed and scraped from any afhering particles of lime or other substances. When this has been done the skins are subjected to the action of mustard seed, which forms the distinguishing charasteristic in this process. It is carried out in the following manner: A vat of proportionate size is filled with a sufficiency of water to cover the skins, and to this water there must be added for every hundred pounds weight of the skins, when dry, five pounds of ground Italian mustard seed, and five pounds of barley meal. When these ingredients have been thoroughly mixed with the water, the skins must be dipped therein, so that they may be perfectly saturated with it, and they must be left in this dip for the following length of time
Calf, sheep, or goat skins 24 hours
Light hides and kips 36 "
Heavy hides, for sole leather 48 "
When this time has expired the skins must be taken out and hung up to dry, but only partially, as when subjected to the next process they should still be in a damp condition. The dip which has just been described has a very powerful action on the skins; the combined action of the mustard seed, barley meal, and heat thereby generated, is to open the pores of the skins, and thus to render the remaining processes in tanning them by means of bark much more speedy than under any other methods hitherto known.