The tin salt is placed in a blue stone jar, with the acid, and the whole is stirred until perfect solution is effected. The ether, alcohol and water are then added and stirred in successively. This process, patented by Prof. J. C. Booth, of Philadelphia, is founded strictly upon scientific principles. The tin, salt and acid, are the bleaching agents, while the alcohol, ether and water are dilutants as well as protectives against any destructive agent of the former. Its whitening effect extends throughout the hide, and is not limited merely to the surface. After the application of the liquor, the leather is oiled, dressed and rolled, as in the usual currying process. This mixture is not applicable to leather tanned with black oak-bark, as it colors it yellow. CHAPTER VI. PATENTS FOR TANNING. The following described processes for Tanning have been patented at different periods since 1849. The first may be denominated Hibbard’s patent, issued to Mr. Hibbard, of Henrietta, N. Y. A patent for a modified process in tanning leather, which is specially applicable to light skins, but may be used in all kinds of tanning. The gist of the invention consists first, in a modified process of unhairing the skins, by a composition of lime, potash and salt, by which the process is very much shortened; and secondly, by combining what is called the process of _plumping_ with that of _tanning_. It is alleged by the patentee that the process of plumping, which consists in the use of acids, to open the pores of the skins, is like that of rising dough by yeast; namely, that after the pores have once been fairly opened, if the tanning process is not commenced immediately, they will soon begin to close; as dough once raised, if not transferred at the proper time to the oven to be baked, will fall, and an inferior bread will be the result. The process of tanning therefore, as set forth by the inventor, consists in the combination of the plumping and the tanning process, so that as soon as the acids have acted to open the pores of the skins, the tannin present in the liquor, shall enter and perform its part in the operation. The next may be described as Towle’s process, or improvement in tanning. Issued Oct. 7, 1851. What I claim as my invention or discovery, as a new and useful improvement, and desire to secure by letters patent, is the use of arsenic or arsenious acid, substantially in the manner and for the purposes herein set forth; the peculiar properties of arsenic, by which it tends to suspend the natural tendency of the animal fibre to decomposition upon the extinction of animal life, are well known, and of course they are not patentable; but their application to the processes of tanning, and otherwise preparing skins and hides for useful purposes, by which they are rendered stronger and more durable, is believed not to have been heretofore known and used.