contained in the size take place as fast as in any other variety of size, hence the size of tragacanth has no superiority over any other, besides the best, or picked-leaf tragacanth of Smyrna costs about four times the price of the best Carrageen.

For the preparation of the size, take 3 ounces of tragacanth, pour two quarts of water over it, leave it stand for 24 hours, then stir well and leave it standing for 12 hours more, repeat this until the homogeneous thick mucilage has been produced, then add 4 quarts of water, again stir it up well and filter it and the size is ready for the marbling process.

For tragacanth size, colors of great consistency, mostly fine earth colors are the best. They must be ground exceedingly well and very little ox-gall is to be added. But as these earth colors lack in the power to spread out and in divisibility, a characteristic of colors prepared for carrageen size, and as they never will have such fineness and smoothness, always appearing rugged, it is impossible for me to recommend gum tragacanth for the preparation of size.

I must mention further an effect, which earth colors exert on tragacanth size, viz., that they can be used on paper not prepared with alum, without running, while this is not the case with colors, which were prepared for the Carrageen size. In another chapter upon ox-gall I shall explain why the colors used with Carrageen size must be transferred on alum paper.

Salep, Plantago-Psyllium.

SALEP, PLANTAGO-PSYLLIUM (Flea-bane)
AND THE OTHER GELATINOUS BODIES.

Radix salep are called the dried tubers of several species of orchids, they are round, quite flat, yellowish white, horn-like, semi-diaphanous, very hard and without taste or smell. Formerly salep was imported mostly from Persia, but now the tubers of orchids grown at home are collected and do not in any way differ from those coming from Asia. They contain a good quantity of gum and on that account are used for finishing silks and for medicinal purposes. It is sold ground, or as powder and can be bought at every drug-store. As marbling size, salep possesses very excellent properties, similar to carrageen moss, but its high price prohibits its general application. In preparing size, use, to 6 quarts of water 2-1/2 ounces of powdered salep which must be well boiled for a long period so that it may become entirely dissolved. After standing 24 hours, it can be used in the same way, as carrageen size.

Plantago-Psyllium (Flea-bane, Flohsamen, Flohkrautsamen) is the seed of different species of Way Bread belonging to the family of the plantaginea viz., plantago-psyllium, Pl-Arenaria, Pl-Cynops, the second of which is found in Eastern Germany, Switzerland, Hungary, etc. on sandy fields, the other two on the sea-shores of southern Europe.

The seed is small with one side flat and the other concave and has a furrow upon which is located the eye or navel. It is lustrous and of a reddish brown color, the best varieties coming from southern France. In consequence of the great quantity of plant-mucilage or gum, that it contains, by treating with hot water a consistent mucilage or size is obtained and used in the manufacture of marbled paper and for finishing textile fabrics.

To prepare the size, place 4 ounces of flea-bane in a wide wooden tub, pour 6 quarts of boiling water over it and beat well with a switch of wicker-rods until the gum is entirely separated from the seeds, allow it to cool and after 10 or 12 hours filter through a linen cloth, when it is ready for use. The mucilage of flea-bane is quite homogeneous and of great consistency, is very viscous, forming strings very readily and is therefore not used for drawn edges since the colors will be drawn along by the stylus without being cut. It is mostly used for producing thickly veined, ordinary marbled edges, but flea-bane size is also much more expensive than that of carrageen moss and on the other hand its quality is so much inferior to that of the other that I cannot recommend it for use as size.

I will briefly mention the other vegetable matters containing an especially large quantity of gum or mucilage, but which have not come into use for preparing marbling size on account of their cost and of the less consistency of their mucilages.

The richest in this regard are the seeds of quinces and linseed. Their mucilage is as viscous as that of flea-bane. Much less gum is contained in the leaves of mallows of colts-foot or of marsh-mallows.

In closing this chapter upon the mucilages of plants and their applications as sizing for marbling I again recommend carrageen moss as the best size, because it has given me during my investigations and in practice, surprising results of its usefulness for all kinds of marbled edges.

OX-GALL.

OX-GALL.

THE CHEMICAL CONSTITUENTS OF OX-GALL.

In the bile of every animal are two peculiar acids both containing nitrogen. One of them free of sulphur, the other containing it, both by boiling with acids and alkalis yield the same acid free of nitrogen, which is called cholic acid.

If these two acids be separated from each other in a chemical way we obtain glycocholic acid, an acid free of sulphur and the other taurocholic acid containing sulphur. The alkali salts contained in bile are quite soluble in water or alcohol but insoluble in ether. To produce it in a pure state mix the bile with as much animal coal, (spodium) so that finally, on evaporation in the water-bath a dry powder results, from which is drawn, by the use of absolute alcohol, the now colorless cholic acid esters, cholesterine, choline, lactic acid, etc. When ether containing a little water is added, the cholic acid esters are precipitated as colorless plaster-like masses and crystallize, when left in the fluid for some time.

The so-called crystallized bile is the final material for the preparation of acids. The acids of ox-gall have been investigated in the most thorough manner.

Glycocholic acid is obtained as a colorless precipitate from a watery solution of crystallized ox-gall, by adding dilute sulphuric acid until the fluid becomes flocculent, which after a while, especially, if the water contains a little ether, is changed into a voluminous 'magma' of fine white needles.

If collected upon a filter, these needles unite and form a lustrous felt.

Glycocholic acid is sparingly soluble in water but soluble in alcohol. It forms the principal constituent of bile, it reacts feebly with acid and tastes bitter-sweet. Taurocholic acid is found only in small quantities in ox-gall and has no important effect on the colors.

THE EFFECT OF OX-GALL UPON COLORS.

By chemical analysis we have seen that glycocholic acid is the principal constituent of ox-gall and in combination with taurocholic acid, glycin, choline and lactic acid is soluble in water. On the other hand, when pure, it is soluble with difficulty and therefore is only of use to us when in combination with other acids, as it must combine