252 ANNUAL OF SCIENTIFIC DISCOVERY. 



PRELLER'S PATENT LEATHER PROCESS. 



The following is a description of the improvement in tanning and 

 preparing leather, which has been highly praised in England during 

 the past year. 



The first stage of the process is analagous to that which the hides or 

 skins undergo in the tan yard. When the horns have been removed, 

 the hides are slightly washed, and then unhaired in the usual manner. 

 Next they undergo a partial drying, and receive a uniform coating of a 

 peculiar paste, the composition and mode of preparation of which is 

 fully detailed in Mr. Preller's specification, and explained generally in 

 No. 1519 of the Mechanics' Magazine. This paste is worthy of notice, as 

 constituting the main feature of the invention ; but it will be sufficient 

 for our purpose at present merely to state its general nature, as being 

 a compound of various vegetable, animal and saline substances. The 

 choice of the vegetable substances employed is determined by the 

 condition that they shall contain a large proportion of starch and little 

 gluten such, for instance, as barley flour, rice flour, or starch itself. 

 The animal substances are of an oily or fatty nature, the patentee pre- 

 ferring ox-brains, butter, milk, animal oil, and grease. Salt and salt- 

 petre are used merely as preservatives for the brains and the butter. 

 As barley flour contains an abundance of starch 720 parts in 1,000, 

 according to the analysis of Einhof this material has been economi- 

 cally selected to form the basis of the impregnating paste, and the 

 other materials added, serve to give properties to it for which the 

 gelatinous nature of the skin exhibits a remarkable affinity, the exact 

 chemical nature of which it is not easy to ascertain. 



The paste having been prepared according to the directions con- 

 tained in the specification, which involve the most simple appliances, 

 and but a small amount of labor, the hides are laid upon large tables, 

 where they are smeared with it on the flesh side, and in that state they 



* 



are put into the interior of large drums, mounted upon horizontal 

 axles, to which a rotary- motion is imparted. They are each about 9 

 or 10 feet in diameter, and 5 feet long, and are furnished with a square 

 hole at each end through which the hides can be passed. Around 

 their inner peripheries a number of stout pegs are disposed radially, 

 the intention of which is to agitate the hides forcibly, so as to effect 

 an equal distribution of the moisture they still retain, and the com- 

 plete and uniform absorption of the paste throughout their fibrous 

 system. The drums are driven by a derived motion from the shafting 

 of a steam engine, can be readily thrown into or out of gear, and 

 their speed is susceptible of ready adjustment, according to the state 

 of forwardness of the process. To promote a drying action, which is 

 frequently desirable, the Avaste steam from the engine is conducted 

 into a large chest, from which a main passes along the floor near the 

 cylinders, and a communication is effected between this and the inte- - 

 rior of the drums by the use of connecting pipes and hollow axles 

 which can be closed or adjusted by a stop-cock. Having been kneaded 



