40& Mr. Stephens on the [Dec. 



of each, for instance) are now to be separately submitted to the 

 action of test skins (to be described afterwards) which should 

 be carefully handled in the liquors now and then for seven or 

 eight hours to expose new surfaces to the action of the ouze, 

 till the tanner ascertains by eye and tongue that the liquors are 

 absolutely spent. 



There are a number of critical appearances in various opera- 

 tions, altogether undescribable, and of which inanimate tests 

 give us no warning, and keep no record : in such cases it fortu- 

 nately happens that the organs of sense give perfect satisfaction 

 to an experienced operator. In the process under consideration, 

 habit renders their decision all-sufficient. 



The skins intended for the trial should previously be well 

 washed in tepid water to extract any lime which they may have 

 absorbed in the process of depilation, together with all the loose 

 gelatine which can be squeezed out of the pores along with it ; 

 so that nothing shall remain but the firm fibre, which will bear 

 handling in the usual manner in weak ouze. They are, after this 

 washing, to be dried in the shade, but not near a fire ; then cut 

 up into small pieces to fit the miniature tan-pits, and weighed in 

 lots corresponding with the infusions ; each lot containing bulk 

 sufficient to fill up the quantity of ouze, and (Hke a sponge) pre- 

 sent an absorbent surface on every side. 



This dry skin (as every tanner knows) is in a very unfit state 

 to absorb astringent matter and become leather. It is, there- 

 fore, previous to immersion in the ouze, to be worked with the. 

 hands for about five minutes in water just blood-warm (98°Fahr.), 

 and induced by this treatment to soften and swell to its former 

 dimensions, in which state it will be capable of fully exerting its 

 absorbent powers ; and if care be taken to give the ouze an over 

 dose of it, the action will be completed in a few hours. 



As each ouze is exhausted, its lot of skins should be taken up, 

 dried in the shade as before, and the increase of weight in each 

 lot separately ascertained. This additional weight can consist 

 only of the useful tanning matter, so that the increase of each 

 lot will directly show the true comparative value of the astrin- 

 gent in whose infusion it was steeped. 



The skin most proper for this purpose is the strongest and 

 freshest that can be procured, shaved down or split to the thin- 

 nest substance it can be safely reduced to. The large fresh 

 currier's shavings from the strong hides intended for chaises or 

 harness, can be obtained in quantity, and are well adapted to 

 the process. The skins of ill-fed sheep and cattle that come to 

 market hidebound from the mountain districts, as well as those 

 of aged cattle in general, are also strong and fibrous enough for 

 the purpose ; but what I would prefer to all others (from the 

 description I have received), are ox hides spht very thin and 

 evenly by the patent machine. 



