insurmountable proclivities, 1st, they do not mix so intimately with oxides of metal as the organic coloring stuffs of plants and they cannot for a long period withstand the influence of light.

In the meantime it is to be hoped with confidence, that science will soon find the solution for these difficulties. Already the forerunners of body colors have been discovered, a few which could withstand light have followed, as geranium lake in which the coloring matter is only bound to oxide of lead by surface adhesion. Furthermore scarlet lake, which, although bound to oxide of lead, has been put in such a state that it does not run and lastly the artificial krapp-(madder) lake and indigo, which have been produced from coal-tar and nearly equal to the good color lakes of the animal and floral kingdoms.

The main attention in the production of these colors is directed to the end of finding those which are free of poison and will not fade, to make them serviceable to the historic art of painting.

For the aniline color there is therefore a wide field open to experiment.

Whether our interests and demands in regard to colors will be fulfilled is a question of time.

Even the newer productions of the animal and vegetable kingdom already differ in quality from those indispensable to the art of marbling.

I recommend to my honored colleagues to read my book with attention, so that the intended gain shall not be missed and the beautiful art of marbling may attain a larger circle of friends.

The Author.

THE SIZE.

THE SIZE.

The first process in marbling is the preparation of the size on which the colors are to be floated.

By the name of size is meant a consistent glutinous mass, which is obtained by boiling or dissolving with water certain bodies derived from the vegetable kingdom.

Mucilage is found in many plants, especially in the outer skin of seeds, also in many roots, barks, stems and leaves, but its solubility and consistency are very much varied.

Generally the mucilage of plants is classed among the gums; but there is a large difference from them in this, that it will not give a perfect, diaphanous and homogeneous solution, but only swells in it to a thick, massy and viscous fluid, which is similar to starch paste. It is composed of small quantities of gum, starch, sugar and consistent plant-mucilage. If prepared from certain plants, for example the algae of the sea, it also contains small quantities of iodine.

Starch swells in hot water, while with mucilage the same result is achieved by using cold water.

Smaller quantities of mucilage are found in every plant, but larger in gum tragacanth, carrageen or Iceland moss, salep, the leaves of mallows, or of colts foot or tussilage, the roots of marsh mallow, seeds of plantago-psyllium, (flea-bane) linseed and quinces.

Of this number but few are of interest to us, which I shall mention further on.

The density and proper consistency of the size depends on the bodies, from which the viscous or glutinous substance is derived and also from the quantity of water, in which it is dissolved. The consistency of the size is also materially influenced by the temperature, the warmer, the less substantial and the more pliable; the colder, the more consistent and stiff it is.

A good marbling size should be an entirely homogeneous mucilage, i. e., a solution, which should be free of any vestiges of seeds or strings undissolved. A less viscous size is more adapted to the production of comb-edges, while a more viscous size to the production of marbled or veined edges. The consistency of the mucilage of every kind of size will soon experience an essential change, which becomes apparent by the fact, that the size becomes less consistent, until finally an acid reacting fluid remains, which has no more value for marbling purposes.

This chemical process is produced by the transformation of the sugar parts of the dissolved starch contained in the size into acid and lactic-acid. The more starch and sugar that is contained in the size, the sooner the acid will be generated, while pure plant mucilage containing but little sugar and starch will resist much longer disintegration.

All plant-mucilages, which are soluble in cold water, i. e., swell, will keep much longer than those dissolved in boiling water, because the soluble parts remain inclosed in one cell which is only broken by the boiling heat or by the formation of acid. This is the reason why they only swell up in cold solution.

A homogeneous mucilage will serve for marbling much better, than that, which is produced by swelling, because the latter has an injurious influence on the fine distribution of color for veined, comb and other edges. Although the surface of such a size seems to be smooth, the eye will discover on closer investigation the undissolved bodies in the small granules of the size.

The mucilages obtained by swelling are always milky-cloudy and never permit the colors distributed upon them to expand with the same purity and smoothness as the homogeneous varieties, on account of the small granules hindering the drawing of the colors on their surface. On the other hand there are varieties of size, which are very viscous on account of a too homogeneous mucilage and therefore from their nature are not adaptable to any kinds of edging which must be drawn by the stylus. The colors can simply not be drawn on the surface, because this very viscous mucilage is drawn along by the stylus instead of being cut by it.

In investigating the different varieties of size I have noticed a very surprising action of the extremely viscous mucilage, which nearly confused me for the moment. I have scalded with boiling water plantago-psyllium (flea-bane) and have beaten it with wicker-rods tied together so as to produce in a better manner, the mucilage found on the outside of the seed. After cooling it off, I filtered it through a linen cloth and poured it into the trough but have not waited till the very viscous thread of mucilage parted after the trough was filled to a certain height, but have placed the vessel on the floor and to my utter surprise the thread of the size spread out and reached the vessel on the floor, becoming gradually thicker until finally the whole size flowed in a white stream with great velocity over the rim of the trough (2 inches high) and returned to the vessel standing on the floor until the trough emptied. This was done in a very short time. The cause of my surprise was in the very consistent mucilage which took along ever-increasing quantities of the size and finally entirely emptied the trough.

Prepared colors, which on a less viscous size are normally distributed expand with a greater velocity to a greater extent on a more viscous size and therefore become pale.

For such kinds of sizes the earth colors are preferable but only for marbled edges.

The normal strength of size can be discerned without araometer or other recommended apparatus. My opinion is that 2/5 of an ounce of good carrageen moss to a quart of water are sufficient, as carrageen excels all other glutinous bodies by the quantity of mucilage contained in it. To test the correct strength of the size pour some of it into a flat vessel, as a plate or dish, and throw a drop of color upon it; if the color