Hides to be tanned for bag leather receive a treatment which is little different in fundamental principle from that of dressing hides for upper leather, except that the tannage is usually shorter. Hides for bags and portmanteaux represent a type of dressing leather in which the outstanding features are that the goods are split but not rounded. The splitting is done at all stages, according to the requirements of the tanner. Some tanners split "green," _i.e._ split the pelt itself. The advantage of this is that the fleshes may then be treated in quite a different way, _e.g._ pickled or given a much cheaper tannage. Other manufacturers split after tanning, the advantage being that there is much less material to handle. The general opinion, however, favours a middle course in which the hides are split after being in the tan liquors for a short time. The advantage of this course is that the hides are easiest to split under these conditions--a great consideration--being coloured through with tan, just a little plumped, but not hard. A smoother flesh is obtained together with more even substance. Here again, however, are differences; some tanners prefer to split after two days, others after two weeks in tan. Much depends upon the nature of the tan and the strength of the liquors. For this class of work, flat, spready and evenly grown cowhides are obviously the most suitable material, and are invariably used. It is important, however, that the grain be good, and free from scratches and similar defects. The tannage must be sweet and mellow, _i.e._ contain no acid and little astringent tan. Hence myrabolans and gambier have always been the favourite tanning materials. A soft and mellow tannage is the more important, inasmuch as the leather is not heavily stuffed with grease in finishing. These types of method for tanning split hides will now be outlined, and the nature of the currying then indicated. _Type 1_.--In this a long mellow liming of 15-16 days is given, much like that described for harness leather in Section III., Type 3. Only lime is used, but the liquors are not allowed to get dirty. The three-pit system is much the best. The hides are trimmed at the rounding tables, and then bated in hen or pigeon dung for three days at 75°-85° F. The deliming is commenced by washing in tepid water before bating, and is completed by a bath of boric acid, using up to 30 lbs. acid per 100 hides as necessary. In this and other processes for split hides it is essential to obtain all the lime out, but to do no plumping with acid. Lactic acid may also be used, but it is not so convenient to hit the neutral point with it.