One particularly troublesome result of having to deal with wood pulp papers is that it will not hold the threads used in ordinary binding; the thread cuts right through the paper because of the shortness or brittleness of the fibres, and if a book printed on such paper has to be bound, the only safe way to do it is to frame each page in a border of sound rag paper, and then have it sewn as usual. Wood paper will not stand bending, but breaks off short if there is anything like a joint or fold in it, and the framing or mounting prevents this. The process of mounting every leaf of a book is, however, a very expensive one; a couple of pounds may well be spent on a comparatively small book for this operation alone, so that the prospect before owners of libraries who wish to keep their books in good order is not brilliant. No amount of dressing can make such paper really strong, as it is the fibres themselves that are in fault. But there is another form in which the use of wood is not so harmful, and in this case the fibres are no longer there to be found fault with. “Chemical” wood pulp is a form of cellulose, and it is likely that it is destined to play an important part in the paper of the future, in conjunction with fibres of various sorts. Chemical wood pulp is prepared from the wood fibres by “digesting” with caustic soda or bisulphide of lime, as reducing agents. The process is one of much interest, and moreover a good deal of wood has to be used to make a comparatively small amount of wood cellulose. Esparto and straw celluloses are not so good as wood cellulose. The invention of the “half-tone” process, by which a dotted block can be produced from a toned drawing, print, or photograph, can be made, is responsible for much dangerous procedure with regard to the paper upon which the prints from the dotted blocks are to be made. In itself the invention of the half-tone process is a wonderful and beautiful one, but it has done more to ruin the already decadent modern paper than anything else, because it has made the dressing of the paper of greater importance than the paper itself. Incidentally, the half-tone block has given the death-blow to the old and beautiful art of wood engraving, which is now only found in quite exceptional instances. But the half-tone block has, nevertheless, provided some small solace for the dispossessed wood engravers, because the soft metal blocks go wrong in light places and themselves need careful revision with a graver. This touching-up is so general, and so much technical skill is required for its proper execution, that it has already become a recognised profession, and the engraver’s name is often enough recognised in the lettering of the prints made from such blocks, especially in American publications.