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 h.o.m.ogeneous 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 h.o.m.ogeneous 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 h.o.m.ogeneous 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 h.o.m.ogeneity 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 h.o.m.ogeneousness 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 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 h.o.m.ogeneous 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 quant.i.ty 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-sh.o.r.es 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 l.u.s.trous and of a reddish brown color, the best varieties coming from southern France. In consequence of the great quant.i.ty 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 h.o.m.ogeneous 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 quant.i.ty 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 CONSt.i.tUENTS 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 ma.s.ses 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 l.u.s.trous felt.
Glycocholic acid is sparingly soluble in water but soluble in alcohol.
It forms the princ.i.p.al const.i.tuent of bile, it reacts feebly with acid and tastes bitter-sweet. Taurocholic acid is found only in small quant.i.ties in ox-gall and has no important effect on the colors.
THE EFFECT OF OX-GALL UPON COLORS.
By chemical a.n.a.lysis we have seen that glycocholic acid is the princ.i.p.al const.i.tuent 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 intimately with water-colors.
The atomic weight of gall and the insolubility of pure glycocholic acid in water are the most valuable properties of it for the marbling colors.
The first gives to the colors the expanding power, the latter the adhesion to paper.
All the lower fatty acids, among which ox-gall may be numbered, possess properties similar to fatty bodies, namely a less atomic weight than water. They differ from fatty bodies in this, that they mix with water.
The expanding power and lightness of ox-gall are, consequently, peculiarities of equal value. Marbling size forms the base for the colors, which by the consistency of the glutinous ma.s.s and by the gall added to them are prevented from sinking to the bottom. They float like drops of oil upon the water and only differ from them by the fact that the colors will spread out on the size, while the drops of oil on the water are contracted to circular spots of small size. If a drop of oil were thrown upon the size it would spread out very quickly.
This purely physical occurrence is caused by the different weights of the bodies and the consistency of the size. The fatty bodies, which are much lighter than water, float upon it but the gravity of the drop itself prohibits its spreading out, as it sinks somewhat and is held together by it. It is different with the size; by the consistency of the glutinous ma.s.s the gravity of the drop is antagonized and as a result it flattens and spreads out.
As I have already mentioned the insolubility of glycocholic acid binds the color to the paper. To explain this I will mention a few examples; the saturated alum solution will cause glycocholic acid to curdle. If, therefore, we add to ox-gall which is basic the saturated solution of alum, a soft plaster-like ma.s.s is precipitated which consists of glycocholate of aluminium, insoluble in water. This chemical reaction explains the durability of the colors. If we desire to marble books or papers we impregnate them with alum water, allow them to dry partly and take the edge from the size.
In the same moment that the paper soaked with alum comes in contact with the colors, the latter become bound by the formation of glycocholates of aluminium and do not run. They have the same property of fixing colors that resinous soaps used in the paper manufacture for gluing machine paper have. If this resinous soap were not too strongly basic, which is injurious to many colors, it might be applied as a surrogate for ox-gall.
As the resinous soap on account of its binding quality and insolubility could also be used in marbling with such colors, upon which it exercises no injurious effect, I will here give its preparation and former use in the manufacture of paper. If 2-5 ounces of rosin be boiled with 1-1/3 ounces of sodium lye and if you add by teaspoonful from time to time so much lye until a sample of it is dissolved by hot water to a clear fluid, the ma.s.s on cooling congeals and forms a quite solid soap. If we mix a solution of resinous soap with one of alum then we obtain an insoluble compound of resinous acids and aluminium. In this way resinous soap is used in gluing paper by adding to the paper pulp, first resinous soap and then a solution of alum. During this process a thin layer of insoluble soap of aluminium is formed around every particle of the paper and thus the running of the ink is prohibited. The same process occurs with ox-gall contained in the colors, when the edge is lifted off on paper or book-edges impregnated with alum, by which the running of the colors is prohibited.
THE PREPARATION OF OX-GALL AND ITS USES.
The preparation of ox-gall to be used in marbling is simple. Take a quart of fresh bile (ox-gall or fish-gall), place in a bottle which contains when filled from 1-1/2 to 2 quarts, add 1/2 pint of absolute alcohol, shake well and leave stand for from 14 days to 3 weeks. Within this time all particles of gum and all fatty substances which are present in some galls in comparatively large quant.i.ties, will fall to the bottom and the gall will be thin-fluid, pure and diaphanous, brownish, yellow or greenish according to the nourishment of the animal from which it was taken.
Cow-gall contains more gum and fatty substances, than ox-gall; fish-gall, on the other hand, is thinner than ox-gall and would be the most useful of them all, if it could be obtained in sufficient quant.i.ties. If the gall is thin and pure it is filtered through paper which is easily and quickly done as it runs like water. If by filtering the dregs of the gall the filter should become clogged, a new one must be used.
The addition of alcohol causes the precipitation of glutinous and fatty substances and preserves the gall from decomposition. If prepared in such a way it can be preserved for years without spoiling.