The sprinkling water is here of great service, because, although ox-gall in its pure state possesses a sufficient expanding power it is here more desirable to produce beauty of forms. In this respect the gall is much inferior to sprinkling water, the former producing all kinds of forms, the latter only beautifully round and oval ones. For marbling, the ground color is prepared with gall so far, until it slightly pushes the other colors aside and then, by and by, so much sprinkling water is added until the desired expanding power is reached. Every ground color which is prepared with sprinkling water spoils on standing two or three days becoming slimy and viscous, and, for economy's sake, not more color should be prepared with sprinkling water than is required for one marbling process. For hair-veined edges, the sprinkling water is used in the same way as gall. Use a large painter's brush or whisk and move the colors by beating into veins, with this brush or whisk through a slot, or throw the sprinkling-water upon the color by means of the sprinkling brush and sieve. In both cases the same result will be achieved. ALUM WATER. ALUM WATER. In the chapter upon gall I have mentioned in a general way the action of alum water upon the edges, it remains only therefore to explain the preparation and application of the same. To achieve beautiful results from the colors it is indispensable to wet the book edges or the paper, to be marbled, with concentrated alum water, so that no spot is left free from moisture, because at that spot the color would not take. Concentrated alum water is prepared in the following way; put 2 quarts of water and 13 ounces of alum into a pot and heat until the alum is entirely dissolved. This concentrated solution is permitted to cool and is bottled tightly. A solution of alum in cold water is much too weak for the above purpose as alum is but sparingly soluble in cold water. The book edge or paper, which is to be marbled, is wet with a sponge dipped into this cold concentrated alum solution and must be allowed to dry for from 5 to 8 minutes, after which the produced edge may be lifted from the size. Generally this point finds but too little consideration in our book-binding establishments. Edges which have not been treated with this alum water show as a consequence poor and blotted results, although such little trouble is necessary to wet the edges with alum water. With hair-veined edges, where colors are thrown on the size only in very small quantities, this wetting may be omitted; but with comb, peacock and bouquet edges, for which four to six colors are used, it is unavoidably necessary to prepare the edges with alum water because the glycocholate aluminium formed by the color while in connection with the alum water is essential to fix the color in such quantities.