The size and the technical application of the colors demand great attention and practice; on the other hand, the preparation of colors but labor. The colors are divided into two groups, mineral and lake colors. In the lake colors, if they are good and strong, the coloring matter bound to the metallic oxides is equal to one-half of the whole weight of the color, therefore they can be prepared as good marbling colors without adding anything but gall. On the other hand, in mineral colors, which in a natural or chemical way are bound to bodies, the body weighs much more than the coloring substance and even if the metallic oxide is the real coloring substance, as is the case with ferric hydrate, the organic coloring matters derived from the vegetable or animal kingdom are preferable to the inorganic substances. Why this is the case we shall see further on. In those coloring substances, which I have recommended as good marbling colors, the aggregate state of the body is amorphous and admits of the greatest divisibility. If such a coloring substance is ground in the finest way possible, the division of the body is a very great one, but an intimate union of the particles can never take place because first, the color is insoluble in water and, second, because the division (diminution) of a body has its limits. For this reason particles are isolated and lay loosely alongside of each other. If a mineral color is mixed with the necessary amount of water and gall and thrown upon the size the drop expands to a round disc, which upon close investigation, is found to consist of numberless small dots. When such coloring stuffs are used, the union of the particles must be brought about by some glutinous matter. This is unnecessary with lake colors, where the coloring matter is as heavy as the body to which it is bound, as all organic substances possess a sufficient quantity of glutinous matter to form a union of the particles. The clearest proof of the correctness of my allegations we find in a mineral color, in which the metallic oxide was precipitated by a semi organic salt, I mean French blue, which without any substance unites the particles quite well if the washing of the precipitate after the blueing, was a perfect one.