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Fruits should be gathered before they are quite ripe; but seeds, the least perishable of vegetable productions, must be perfectly ripe, and require very little drying.
Crude vegetable drugs are rarely deprived of all their inherent moisture by the drug-gatherers, and invariably reabsorb moisture when exposed to a damp atmosphere; before such drugs can be mechanically subdivided they frequently require a further drying by artificial heat, which is effected by spreading the material loosely on shelves in ventilated apartments heated by steam. While drugs containing volatile constituents, such as buchu, valerian, myrrh, spices, etc., demand a moderate heat, others again can be strongly heated until they become brittle, as, for instance, squill; a temperature kept at or below 45° C. (113° F.) will not prove injurious in any case.
The amount of moisture present in freshly gathered botanical drugs varies considerably, ranging from 15 or 20 per cent. in barks and wood to as much as 80 per cent. or more in some roots and leaves, and the object of thorough drying is partly to reduce the bulk, but chiefly to preserve the drug for future use; for if vegetable drugs be packed away in a moist condition they soon begin to mould, or become heated, and undergo rapid deterioration. The loss in weight experienced by thorough drying of drugs is in many cases more than compensated for by the increase in value of the dried article, as in opium and other alkaloidal or resinous drugs. If opium containing 10 per cent. of morphine and 25 per cent. of moisture be dried perfectly, the loss in weight will amount to onefourth, but the relative proportion of active principle is increased one-third ; jalap tubers containing 8 per cent. of resin and 34 per cent. of moisture will lose upon drying about one-third of their weight, but the proportion of resin present is increased 50 per cent. Dried botanical drugs are best preserved in cool, dry rooms in containers which shall exclude sunlight, but permit of free circulation of air; odorous drugs should always be kept separate in order to avoid contamination of others; for instance, a bale of buchu, valerian, or sassafras should never be stored by the side of senna leaves, elm bark, or flaxseed.
As crude drugs reach the pharmacist they are frequently not in a condition to be offered for sale, or to be used in the preparation of medicines, on account of impurities present, and the process of garbling is a very necessary operation. The object of garbling, or picking, is to remove, besides impurities and adulterations, decayed and deteriorated portions of the drug, which not only mar the appearance but are apt to contaminate the still healthy portion, and soon render the whole worthless. Senna leaves are generally accompanied by a considerable proportion of stems, broken capsules, and dust, not to speak of the fraudulent admixtures of stones, shells, etc., made by the gatherer or exporter for the purpose of increasing the weight; as much as 15 per cent. of impurities has been taken from
what was bought as prime senna. Juniper berries are never free from unripe and decayed fruit, dirt and worm-eaten portions, which should be carefully removed. Fibrous roots, as spigelia, wild ginger, serpentaria, and the like, require to be freed from adhering dirt and other roots that grow side by side with them, and have become mixed through careless gathering. Although some drugs are found in much better condition than others, there are none which be improved in appearance, even if it be only to have the fine dust and dirt removed, as in the case of sassafras, wild cherry, crushed oak-bark, etc.; lycopodium, fennel, flaxseed, and similar drugs, should be well shaken in a suitable sieve, to remove foreign matter, before putting them away in containers, and the careful pharmacist will find that this little extra labor is readily appreciated by his patrons, who are apt to judge a man largely by the appearance of his wares. Even vegetable powders, such as ipecacuanha, nutgall, and others of similar character, must be passed through a fine sieve, preferably bolting-cloth, to remove coarse particles which unfit them for dispensing purposes, and which have, in some instances, been found to amount to as much as 25 per cent. of the total weight of the powdered drug.
MECHANICAL SUBDIVISION OF DRUGS.
BEFORE employing vegetable drugs in the various pharmaceutical preparations it often becomes necessary to reduce them to a state of comminution, or of powder, more or less coarse or fine as the nature of the drug and the desired preparation may demand. By simple contusion is generally understood a rather coarse division, brought
about by crushing or bruising in suitable apparatus preparatory, to finer reduction; for small operations an iron or brass mortar of bell or urn shape is employed, which should be deep and with a broad inner base, as shown in Fig. 76, the pestle being of such length and weight as will enable the operator to exercise considerable force if necessary.
In contusing substances only such a quantity should be placed in the mortar at one time as to cover the bottom for the depth of an inch or two, and to avoid loss or unpleasant results from the escape of dust or particles of drug, a cover, provided with a hole through which the pest le passes, should be used. In place of the mortar and pestle a cutting knife can frequently be used with advantage. The Champion Knife No. 2, Fig. 77, made by the Enterprise Manufacturing Co., of Philadelphia, is well adapted for the coarse division of roots, barks, and herbs,
as it combines a drawing motion with pressure while cutting the material. When operating on large quantities, steam power is necessary, and the best apparatus for the purpose is that known as Mead's Disintegrator (see Figs. 78, 79, and 80). The grinding is done in this mill by hardened steel beaters securely riveted on both sides of a steel disk. These beaters revolve on the feeding side of the mill between corrugated rings. The beaters catch the material as it enters the mill and beat it against the corrugates until it is fine enough to pass between the
Sectional view of mortar and pestle
disk and the face of the ring; as soon as it passes here it is on the discharge side of the mill, and all that is fine enough is immediately
driven out by the beaters on the back of the disk. What is not fine enough to discharge is caught by these back beaters and beaten against the screens until fine enough to pass through. The screens are made of square steel, and present a grinding surface to the beaters and a discharging surface between each bar; they are two inches in width and extend around three-fourths of the diameter of the mill, thus giving a large discharging surface without diminishing the grinding surface. The material, as it is ground, falls into the box or room below. The most effective work is achieved with the disintegrator running at high speed, three thousand revolutions per minute; under such conditions, six hundred pounds of wild cherry bark can be finely crushed in an hour.
a. Section of steel screen; 0. The production of very fine powders of Section of corrugated ring; c. drugs has long since passed into the hands Steel disk with beaters attached. of the drug-miller, and even the coarser powders intended for percolation are to-day prepared by only a small number of pharmacists. For the latter purpose the drug mills shown in Figs. 81 and 82 will be found very desirable In the New B Swift Mill the grinding is done between plates placed horizontally, while in the Enterprise Mill they are placed vertically. The grinding surfaces of both mills consist of circular chilled-iron castings studded with concentric rows of sharp teeth, those of one plate fitting between those of the other. The teeth decrease in size toward
the centre, and the fineness of powder is regulated by a pair of screws, by means of which the plates are made to approximate each other. One of the plates is stationary while the other revolves. Separate sets of plates for coarse and for very fine grinding can be had for the mills. Care should be taken to thoroughly clean the mill after each operation, else the remaining dust will surely contaminate the drug next ground. The simplest method of cleaning is to run sawdust through the mill repeatedly, then loosen the screws and remove the grinding plates, so as to wash these with hot water, if necessary, and dry quickly. A great mistake often made by the inexperienced is the attempt to produce fine powders at once by screwing the plates close together, instead of grinding the drug coarsely at first and gradually tightening the mill; the first plan is apt to cause the material to become heated and cake, while the second plan will achieve the desired end more perfectly, with far less