Every Turkish pasha sets his pride on a rich collection of pipes, as it is the hospitable custom of the Orient to offer a cup of coffee and a hookah or tschibouque to a stranger; and this fashion is of no small importance to the amber-dealers of the Baltic. A somewhat inferior quality is sent by way of Copenhagen and London to China, Japan, and to the East and West Indies.
Russia also consumes a considerable quantity of amber, which is very elegantly turned or manufactured in St. Petersburg and Polangen, and thence finds its way over the whole empire. Here, as among the Turks, only the translucent and perfectly opaque white qualities are esteemed; the latter being chiefly employed for the manufacture of the calculating tables which are commonly used by the Russian merchants. Necklaces of transparent amber are in great request among the peasantry of Hanover and Brunswick, where strings of pale-coloured crystalline beads weighing from half a pound to a pound are worth from fifty to sixty dollars.
Amber of a deeper colour and of a rounded form is chiefly exported to Spain, France, and Italy.
Thus each country chooses according to its taste among the abundant amber-masses which extinct forests furnish to the inhabitants of the Baltic coast-lands, and which trade, through a hundred known and unknown channels, scatters over the whole surface of the globe.
CHAPTER XXXVII.
MISCELLANEOUS MINERAL SUBSTANCES USED IN THE INDUSTRIAL ARTS.
Alum—Alum Mines of Tolfa—Borax—The Suffioni in the Florentine Lagoons—China Clay: how formed?—Its Manufacture in Cornwall—Plumbago—Emery—Tripolite.
Alum, a double salt, consisting of sulphate of alumina (the peculiar earth of clay) and sulphate of potash, or sulphate of alumina and sulphate of ammonia, was known to the ancients, who used it in medicine, as it is now used, and also as a mordant in dyeing, as at the present day. Their alum was chiefly a natural production, which was best and most abundantly obtained in Egypt. In later times Phocis, Lesbos, and other places supplied the Turks with alum for their magnificent Turkey red; and the Genoese merchants imported large quantities from the Levant into Western Europe for the dyers of red cloth. In 1459 Bartholomew Perdix, a Genoese merchant who had been in Syria, observed a stone suitable for alum in the Island of Ischia, and burning it with a good result, was the first who introduced the manufacture into Europe. About the same time John di Castro learnt the method at Constantinople, and manufactured alum at Tolfa. This discovery of the mineral near Civita Vecchia was considered so important by John di Castro that he announced it to the Pope as a great victory over the Turks, who annually took from the Christians 300,000 pieces of gold for their dyed wool. The manufacture of alum was then made a monopoly of the Papacy; and instead of buying it as before from the East, it was considered a Christian duty to obtain it only from the States of the Church. With the progress of Protestantism, however, the manufacture began to spread to other countries. Hesse-Cassel began to make alum in 1554, and in 1600 alum slate was found near Whitby in Yorkshire.
Alum-stone is a rare mineral, which contains all the elements of the salt, but mixed with other matters from which it must be freed. For this purpose it is first calcined, then exposed to the weather, in heaps from two to three feet high, which are continually kept moist by sprinkling them with water. As the water combines with the alum, the stones crumble down and fall eventually into a pasty mass, which must be lixiviated with warm water, and allowed to settle in a large cistern. The clear liquor on the surface, being drawn off, is to be evaporated and then crystallised. A second crystallisation finishes the process, and furnishes a marketable article. Thus the Roman alum is made; but its production being far from enough for the supply of the world, the greater portion of the alum found in British commerce is made from alum-slate and analogous minerals, which contain only the elements of two of the constituents, namely, clay and sulphur, and to which, therefore, the alkaline ingredient must be added.
Borax, or Borate of Soda, is a substance extensively used in the glazes of porcelain, and recently in the making of the most brilliant crystal when combined with oxide of zinc. Formerly its chief supply was obtained under the name of Tincal, from Thibet, where the crude product was dug in masses from the edges and shallow parts of a salt lake; and, in the course of a short time, the holes thus made were again filled. Crude borax is also found in China, Persia, the Island of Ceylon, and in South America; but at present by far the largest quantity used in commerce is derived from the lagoons of Tuscany, where vapours charged with a minute quantity of boracic acid rise from volcanic vents.
Before the discovery of this acid, in the time of the Grand Duke Leopold I., by the chemist Hoefer, the fetid odour developed by the accompanying sulphuretted hydrogen gas, and the disruptions of the ground occasioned by the appearance of new suffioni or vents of vapour, had made the superstitious natives regard them as a diabolical scourge, which they vainly sought to remove by priestly exorcisms; but since 1818 the skill, or rather the industrial genius, of Count Larderel, originally a simple wandering merchant, has rendered these once abhorred fugitive vapours a source of prosperity to the country, and were they to cease, all the saints of the calendar would be invoked for their return.