32; for any number of degrees above or below the freezing-point on the Centigrade scale when multiplied by 1.8 yield the corresponding number of degrees above or below the freezing-point on the Fahren

heit scale.

To convert Fahrenheit into Centigrade: Subtract 32 and divide by 1.8; for any number of degrees above or below the freezing-point on the Fahrenheit scale when divided by 1.8 yield the corresponding number of degrees above or below the freezing-point on the Centigrade scale.

To convert Réaumur into Fahrenheit, or Fahrenheit into Réaumur, substitute 2.25 for 1.8 in the preceding rules.

To convert Centigrade into Réaumur, divide by 1.25; and to convert Réaumur into Centigrade, multiply by 1.25.

×

Examples: Convert 25° C. into F.; 25 x 1.8=45 and 45 +32 =77. Answer, 77° F.

Convert -15° C. into F.; -15 X 1.8-27 and -27 +32= 5. Answer, 5° F.

Convert -40° C. into F.; -40 × 1.8-72 and -72 +32= -40. Answer,

Answer, -40° F.

Convert 60° F. into C.; 60-32-28 and 28 1.8-15.55+. Answer, 15.55+° C.

Convert 18° F. into C.; 18-32-14 and -14÷1.8= -7.77+. Answer, -7.77+° C.

—12.5

Convert -12.5° F. into C.; -12.5-32--44.5 and -44.5 1.824.72+. Answer, -24.72+° C.

=

Convert 30° R. into F.; 30 X 2.25 67.5 and 67.5 +32=99.5. Answer, 99.5° F.

=

Convert -5° R. into F.; -5 × 2.25 — —11.25 and -11.25 + 32=20.75. Answer, 20.75° F.

Convert 50° F. into R.; 50-32-18 and 182.25=8. Answer, 8° R.

Convert 4° F. into R.; 4—32=-28 and -28 2.25: = -12.4. Answer, -12.4° R.

=

=

Convert 60° C. into R.; 60 1.25 48. Answer, 48° R. Convert -8° C. into R.; -81.25 -6.4. Answer, -6.4° R. Convert 28° R. into C.; 28 × 1.25=35. Answer, 35° C. Convert -7.5° R. into C.; -7.5 × 1.25 — —9.37+. Answer, -9.37+° C.

In order to avoid the use of the ordinary long thermometer for temperatures above 100° C., which might frequently prove annoying and give rise to inaccuracies in scientific work, special short thermometers have been devised, so constructed that the graduations of the scale begin a little below the boiling-point of water. (See Fig. 75.) These instruments, known as Zincke's thermometers, are from 4 to 6 inches in length, very accurately made, and are admirably adapted for testing the melting or boiling-point of substances at temperatures above 100° C.

CHAPTER V.

COLLECTION AND PRESERVATION OF CRUDE DRUGS.

ALTHOUGH the collection and preparation of vegetable drugs is not in the hands of the pharmacist, but is carried on, often in a small way, by special drug-gatherers and collectors, it is thought fit to refer to the subject here.

The various parts of plants used in medicine cannot be gathered indifferently at all seasons of the year, since the peculiar juices of the plant in which its activity resides are more abundant in some parts than others at certain periods of the plant's growth. Roots of annual plants should be gathered immediately before the time of flowering; those of biennials, either late in the fall of the first year, or early in the spring of the second year, after the first appearance of the plant above ground; perennial roots should not be gathered until after two or three years' growth, and, in some cases, even four or five years are allowed for full maturity. Fleshy roots must be sliced, either transversely or longitudinally, previous to drying, in order to expose a larger surface to the air; whilst smaller and fibrous roots do not require this treatment. When artificial heat is to be used in drying roots, a temperature of 50° to 55° C. (about 122° to 131° F.) will be found sufficient, except in the case of a few succulent roots, where the temperature may be raised to 65.5° C. (150° F.).

Barks of trees should be gathered in the spring, but those of shrubs in the autumn, for at these seasons they are most readily separated from the wood. Only the inner bark being employed, the outer epidermis should be removed.

Leaves begin to lose their activity after the flowers appear, for the juices of the plant then go toward nourishing the latter; they should therefore be collected when fully developed, before they begin to wither. Leaves of biennials must be collected during the second

season.

Herbs are generally understood to mean the whole plant, although the root is frequently rejected; they should be gathered when in flover. If the flowers are not to be used with the stem, the latter should be collected before the flowers appear, but after foliation.

Flowers are preferably gathered before they are perfectly developed (expanded), since odor and color are then more pronounced; the red or French rose offers a striking example. They should be collected in the morning, after the dew has disappeared, and be dried, without artificial heat, in the shade.

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 may not 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.

CHAPTER VI.

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

FIG. 76.

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 pestle 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 for contusion.