When the vessels receiving the juice become filled, the latter is removed to a cask and reserved for evaporation. This may be done at once, or it may be delayed for weeks or even months, the juice, it is said, not fermenting or spoiling. The evaporation is generally conducted in a copper vessel; at the bottom of this is a large ladle, into which the impurities sink, and are from time to time removed as the boiling goes on. As soon as the inspissation has reached the proper point, which is determined solely by the experienced eye of the workman, the thickened juice is poured into large gourds or into boxes, and allowed to harden.
The drug is not always readily saleable in the island, but is usually bought up by speculators who keep it till there is a demand for it in England. The cultivators are small proprietors, but little capable as to mind or means of making experiments to improve the manufacture of the drug. It is said, however, that occasionally a little aloes of very superior kind is made for some special purpose by exposing the juice in a shallow vessel to solar heat till completely dry. But such a drug is stated to cost too much time and trouble to be profitable.[2563] The manufacture of aloes in the Dutch West Indian island of Curaçao is conducted in the same manner.[2564]
The manufacture of aloes in the Cape Colony has been thus described to us in a letter[2565] from Mr. Peter MacOwan of Gill College, Somerset East:—The operator scratches a shallow dish-shaped hollow in the dry ground, spreads therein a goatskin, and then proceeds to arrange around the margin a radial series of aloë leaves, the cut ends projecting inwards. Upon this, a second series is piled, and then a third—care being taken that the ends of each series overhang sufficiently, to drop clear into the central hollow. When these preparations have been made, the operator either “loafs about” after wild honey, or, more likely, lies down to sleep. The skin being nearly filled, four skewers run in and out at the edge square-fashion, give the means of lifting this primitive saucer from the ground, and emptying its contents into a cast-iron pot. The liquid is then boiled, an operation conducted with the utmost carelessness. Fresh juice is added to that which has nearly acquired the finished consistence; the fire is slackened or urged just as it happens, and the boiling is often interrupted for many hours, if neglect be more convenient than attention. In fact, the process is thoroughly barbarous, conducted without industry or reflection; it is mostly carried on by Bastaards and Hottentots, but not by Kaffirs. “The only aloë I have seen used,” says Mr. MacOwan, “is the very large one with di-or tri-chotomous inflorescence,—A. ferox, I believe.” Backhouse[2566] also names “Aloë ferox?” as the species he saw used near Port Elizabeth in 1838.
From another correspondent, we learn that the making of aloes in the Cape Colony is not carried on by preference, but is resorted to when more profitable work is scarce. The drug is sold by the farmers to the merchants of the towns on the coast, some of whom have exerted themselves to obtain a better commodity, and have even imported living aloe-plants from Barbados.
Nothing is known of the manufacture of the so-called Socotrine or Zanzibar Aloes, or even with certainty in what precise localities it is carried on.
General Description—The differences in the several kinds of commercial aloes are due to various causes, such as the species of Aloë employed and the method of extracting the juice. The drug varies exceedingly: some is perfectly transparent and amorphous, with a glassy conchoidal fracture; some is opaque and dark with a dull waxy fracture, or opaque and pallid; or it may be of a light orange-brown and highly crystalline. It varies in consistence in every degree, from dry and brittle to pasty, and even entirely fluid and syrup-like.
These diverse conditions are partially explained by an examination of the very fluid aloes that has been imported of recent years from Bombay. If some of this aloes is allowed to repose, it gradually separates into two portions,—the upper a transparent, black liquid,—the lower, an orange-brown crystalline sediment. If the whole be allowed to evaporate spontaneously, we get aloes of two sorts in the same mass; the one from the upper portion being dark, transparent and amorphous, the other rather opaque and highly crystalline. Should the two layers become mixed, an intermediate form of the drug results.
The Hepatic Aloes of the old writers[2567] was doubtless this rather opaque form of Socotrine Aloes; but the term has come to be used somewhat vaguely for any sort of liver-coloured aloes, and appears to us unworthy to be retained. Much of the opaque, so-called Hepatic Aloes does not however owe its opacity to crystals, but to a feculent matter the nature of which is doubtful.
The odour of aloes is a character which is much depended on by dealers for distinguishing the different varieties, but it can only be appreciated by experience, and certainly cannot be described.[2568]
Varieties—The principal varieties of aloes found in English commerce are the following:—