in 1460, and a monopolizing grant was made of them by Henry VII. to a merchant of Sienna. The manufacture of this substance received great encouragement, particularly from Lord Sheffield and other gentlemen of Yorkshire. It is of important service in fixing colours, both in washing and dyeing. It is the basis of crayons, which usually consist of the earth of Alum, finely powdered and tinged for the purpose. When mixed with tallow it gives a firm consistency to candles; it is also employed by tanners to assist in restoring the cohesion of the skins when injured by lime,-to dry cod fish, to fine wines,to silver brass without heat, and to whiten silver by paper impregnated with it. Wood and paper

soaked in a solution (4) of this salt are prevented from easily taking fire, and are therefore used in preserving gunpowder, as it likewise excludes the moisture of the air. It is also used in preparing colours, particularly Prussian Blue, and is of essential service in purifying water. The introduction of Alum into bread is thus defended by Dr. Darwin:-"I suppose the use of Alum in making bread, consists in coagulating the mucilage, and perhaps thus contributing to convert it into starch, for the bakers mix it principally with new wheat, and affirm that it makes the flour of new wheat equal to the old. Alum is also used by the London bakers for the purpose of cleansing the river water with which they are supplied,

also to destroy the volatile alkali which exists in some London wells. Its use may therefore be rather salutary than injurious to the London bread, and in some medicinal points of view it may prove serviceable, though in others equally pernicious, therefore its introduction is better abstained from."

ALCOHOL, (see Spirits of Wine.)

ALOE.

There are several species of this plant, possessing various qualities, useful both for domestic and medi

cinal purposes. The species Maguei, of Mexico, appears to be applied to almost every convenience of life. From its trunk beams are formed for the roofs of the houses of the natives, and its leaves are used as tiles; it also serves for hedges and inclosures, besides being convertible into cords, needles, thread, paper, shoes, stockings, and many other articles of clothing. From the juice the Mexicans extract wine, honey, sugar, and vinegar, and the leaves when baked are esteemed an agreeable dish. From the Guinea Aloe very strong ropes are made, not liable to rot in water. Two other species have also been de scribed, one of which is peculiarly serviceable to travellers in hot climates, as the leaves are capable of containing water. The other is manufactured!

into fishing-lines, bow-strings, hammocks, &c. The Aloe is esteemed by the Mahometans as a safeguard against evil spirits and apparitions, for which purpose it is frequently placed over their doors; and this sign often implies that the inhabitant has performed a pilgrimage to Mecca. The Aloe as a medicine is generally known in the form of an inspissated (5) juice, called Extract.

ALOE WOOD, OR XYLO ALOE.

A precious wood, used in the East as a perfume, and is esteemed of greater value than gold. The tree, which grows in China and in some of the Indian Islands, is composed of three different kinds of wood. The heart of the tree is called Tambac, in which jewels are frequently set; this is also used as a cordial. When laid on a fire it quickly consumes, leaving a most fragrant and agreeable smell. It was considered so valuable that it was presented by the King of Siam to the King of France, in 1686, as the greatest gift he could offer. The middle wood, called the Lignum, considered the next in value, is not so strongly aromatic as the Tambac; and the part next the bark, denominated by the Portuguese Pao d'aquila, or Eagle Wood, is black and heavy ; some consider this another species, but this is im◄ perfectly known.

AMERICAN ALOE, OR AGAVE.

A plant common in England, the stem of which generally grows to the height of twenty feet and upwards, and is supposed to blossom only once in 100 years; this by some is attributed to the climate, as in hot countries it flowers more frequently. It has been known to attain the height of 35 feet.

ARSENIC.

A powerful metallic poison, which taken inwardly is generally attended with fatal consequences, arising from its insolubility, (6) and the difficulty of its being quickly decompounded. (7) It is heavy, opaque, and usually sold in white masses, which when broken discover a semi-transparency, resembling Sal Ammoniac, but when exposed to the air become like the original masses. When heated, or struck with a hammer, it emits the odour of garlic, and it may also be known by its rapid volatilization. (8) Most metallic ores contain a proportion of it, particularly tin, copper, bismuth, and cobalt, from the last of which it is extracted, by sublimation. (9) The Sulphuret of Arsenic, called Realgar, is scarlet or orange red, and melts in the flame of a candle. There is another variety, called Orpiment, of a yellow colour; these are used by painters. It is frequently added to produce

opacity, and to facilitate the fusion (10) of glass. It easily dissolves Indigo, when combined with Sulphur, and is therefore of service in dyeing. Its true nature is so imperfectly known, that whether it ought to be ranked among the salts or semi-metals is not decided, as, by various processes, it assumes either a saline or metallic state. It is used medicinally, particularly in cancerous diseases; in Tic Doloreux, and in some distracting pains in the face.

ARNOTTO, ANATA, OR ANOTTA.

A dye, formed from the pulp of the seeds of the Bica, a tree common in South America, of which there are two kinds, one a crimson colour, and the other more of a saffron hue, which last is our Anotta, and is generally supposed to be a mixture of the first sort with certain resinous matters, and with the juice of the root of the tree. Calico coloured with Anotta is called Nankeen, from Nankin, in China, whence it was first brought Anotta is also used in the preparation of

to us. chocolate.

ANTIMONY.

A heavy dark mineral substance, found in different parts of Europe; that procured in England being frequently mixed with lead, is rendered improper