human
may, however, be selected as a typical case. The skins are soaked back, tempered, and either split or shaved, according to their substance and the size of grain wanted. The thin skins of course give the fine grains. Mixed tannages need scouring and possibly sumaching. The skins are then oiled up with linseed oil, sammed, set out and blacked. In this last operation the grain is brushed over with a solution of logwood and ammonia, and afterwards with the iron mordant which often contains glue. They are next hung up for a while and then