Another abnormity which arises from cold temperature acting on the size is the fig-like formation occurring during the drawing of the colors. The cold in some way seasons the surface; this surface becomes mixed in filtering with the liquid part of the size in numberless small particles which although the size is well stirred up in the trough by the fingers, are not dissolved and this hinders the drawing of the colors.

They adhere to the stylus and follow it and arrange themselves between the color lines in a way similar to a green fig, having a broad upper and a pointed lower end. Such an edge traversed by the comb will give an ugly result. A difference of temperature of the size and the air can also occur when the working room is suddenly heated, or, when in summer time, the size is kept in a cold cellar. To effectively obviate this difficulty it is necessary to bring the temperatures of the air and size carefully to the same height which is made easy by leaving the size, after boiling, in the room, where the marbling is executed.

In winter, when the room is heated, the size should be poured into the trough one hour before using, in summer the thing regulates itself because it is then unnecessary to keep the size in a cool place, the addition of borax being a sufficient protection against spoiling. But in spite of it all, in winter-time when in drawing the colors the fig-like formation should occur, it is advisable to return the size to the pot and to warm it up slightly so that the seasoned particles are dissolved, until an equal temperature is reached, whereupon after the lapse of one hour the marbling can again be proceeded with.

Should the size be too thick the trouble can be remedied by the addition of some warm water.

The quantity of mucilage contained in carrageen moss varies greatly, and the consistency of the size often depends upon the quality of the moss. The quantity which I gave as essential to the preparation of the size means first class moss.

Should the consistency of the size be insufficient after the first trial then from 1/2 to 1 ounce of moss should be added as it is clear that the carrageen moss is not of prime quality. Before I speak of another variety of size, I will repeat the main condition which should meet with the attention of every layman and which are as follows; the size must not boil too long, in order that it may not become flaky and muddy, it should remain for cooling in the same room in which the marbling is carried on, so that the temperature of of it and the air are the same; the colors should be prepared separately on a small quantity of size so that the whole size cannot become soiled and, lastly, the top of the size should be taken off before the colors are thrown on, so that no film can form before the colors cover the surface of the size.

The quicker the manipulation of marbling is executed the prettier are the edges produced. As soon as the size is covered with color, the formation of the film is prevented.

As the size is one of the most important parts in the process of marbling, I recommend these main points to the special consideration of the reader.

GUM TRAGACANTH.

GUM TRAGACANTH.

Gum tragacanth, also called gum-dragon, is the product of various species of astragalus which is found in Greece and Turkey and is a natural exudation of shrubs and from exudations resulting from incisions made in the stem near the root. This shrub is from 28 to 35 inches high and two inches in diameter. It is collected in July and August after the exudations have ceased. It is a hard, tough substance more or less white according to its purity in very irregular flattened shapes and in tortuous vermicular filaments. It contains aside from a little gum and starch, a consistent plant-mucilage without smell or taste and it is used in technical ways, in printing of textile fabrics and finishing, in producing plastic masses, as a binding medium for the production of confections and in the book-bindery for marbling size.

The leaf tragacanth of Smyrna is the best. It is brought to the markets of the world via Constantinople or via Smyrna in boxes of 100 to 200 lbs.

It forms flat ribbon-like pieces which consist of peculiar layers of horn-like consistency, white and diaphanous; when broken it is dull and splintered.

An inferior quality is the tragacanth of Morea, which generally comes from Greece via Trieste. This consists of oddly shaped, peculiarly twisted pieces, partly of pure white, partly of yellowish and brownish colors. For a long while, tragacanth was known as a good material for marbling size and, for that reason, it is used to-day in a good many of our book-binderies for this purpose.

It is much more liked than carrageen moss because the consistency of its mucilage and its durability are great and the preparation of the colors does not demand such great attention. But since my experiments and investigations upon the excellent effects of borax on the durability of carrageen size have become known, tragacanth has lost much of its popularity, because with it the edges can never be produced in a similar fine way as with carrageen size and besides the price is higher. Tragacanth is one of these short-viscous plant mucilages which swell in cold water but do not give a perfectly homogeneous solution. The mucilage consists of innumerable small granules, in which the starch is enclosed by cells.

These small granules prohibit, within the first two or three days of a fresh tragacanth size, the drawing of edges, as they make the colors thrown on appear rugged, and in drawing injure the fine hair lines. Five or six days after the dissolving of the tragacanth, the mucilage becomes more homogeneous and therefore better adapted for marbling.

If the swelled up mucilage is boiled, after the first or second day, then the solution will become perfectly homogeneous and will be as good as carrageen size except that the colors, which normally spread out on carrageen size, will expand much more on tragacanth size as it possesses more consistency and therefore they will become paler. The more dense the size, the thicker colors and the less gall is necessary to produce a normal expansion. The same difference in the power of expansion of the colors as in carrageen and the tragacanth is noticed in colors which normally spread out on tragacanth but which, very largely, expand on the size of plantago-psyllium (flea-bane) because the latter has the most consistency and homogeneity of them all. The different effects of the varieties of size on the colors are due to the consistency and to the different conditions of gravity. The objections of the consumers of my marbling colors who use tragacanth, are, that they consider the edges too pale. The cause of this is that my products are only prepared for carrageen size, inasmuch as my investigations have shown that it is the best, the cheapest and the most adapted for all varieties of edges.

The homogeneousness of the tragacanth mucilage in cold solution comes naturally after the size is five or six days old, because within this time fermentation of lactic acid occurs, which opens the cells of the small granules of starch while at the same time boiling heat has an immediate result in the same direction.

As soon as these cells are opened the formation of acids of the sugary parts and the fermentation of lactic acid of the starch