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Calamina praeparata, P. L. 1787.
Zincum calcinatum, P. L. I 787.
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and inclinod lo variis the front of the sire, an other cruci ble heing placed over it, so that the ginc may be CX posed to the air and maybe frequontly stirred With an iron rod. Remove immediately the oxyd whicli fornis: thera pass iis Whi te and lighter part through
directed for the preparation os challi.
In this process the ginc is inflamed, and the oxyd formenthereby is collected; hence the procautions directed as to thesiZe, depili, and temperature of the crucibie, and to the eXPosure os fresti furfaces of the metal by removing the crust of Oxyd whicti fornas Mon iis furface. The metal burns With abright white flame, and liuows up an abundance of whita salaes, the preparation of whicli, for the separation of any adherent unchanged metallic particles, is particularly directed. This oxyd consists of Zinc 80, oxygen 20. It istastes s and insolubie in Water.
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and not so much more expensive as to be an object os importance on this account, to direct the mode of iis prepararition. Perhaps the best method to procure the metal, whicli possesses some malleability, in pieces smali enough to bo easilyacted upon by the acid, is, to divide the et inc by pouring it when melied into water. Sulphate of Zinc crystalliges by evaporation in Dur-sided prisnis terminared by seu sided pyr mids. It is of a transparent white colour, With a Strong metallic astringent iaste. It dissolves in imo and a half paris ofwater at 60', and in much lqss ps botling water. It is notsolubie in alcohol. Ιt consists of oxyd 20, acid 40, mater6O, and is exposed to air loses a smali portion of the lalterand ther emoresces. Some chemisis have lately conside ed ii as a supersulphate.
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olat: press this si si through a fleve mitti large apertures, and after variis through a hair one; then evaporate the Water hy a Water hathuntii the puli' acquires a Proper ConSiSten Ce. Where the fruits are ripe and fre8h, press
The collection os vegetabies, in generat, is not the immediate province of the apothecary ; but, Willi respest to indi-
genous planis, the direction os circumstances relative to their Periods of persection, modes of preservation and botanices Characters, comes under his superintendance; and of theselie must be able to judge when they are offered to him bycollectors. A fuller statement is there re introduced than
Was formerly given, and it is much to be wished that an attention to it was extenden to those of our colonies abroad, whicli furnish articles of Materia Medica, as there is reasOnto hope that the supply of our markets Would then be more uniform in quality than it is at present. It is necessary that vegetable matters should be dried as quickly as possibie, provided the heat applied be not so great as to destroy their colour, and for Whicli purpose expos e to a temperature of 100' is fully sussicient; it is best applied by artificiat heat of stoves, or a beated room, in Whicli the influenco of light is avoided For the fame reasons their continuance in heaps eitherbe re or When drying, is moided, because those Whicli aremoisi and of sost texture, as leaves and herbs, soon ruri intosermentation, especialty in Warm Weather, as is seen in the
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parceis of comum whicli are brought Dom the count to London. The circumstance of age, Which has atready been mentioned, is intended to guard against the probabili ty of the destruction by insecis, as weli as the necessary loss of the more volatile paris of planis. When paris os planis are dried, though they are ultimately to be used in powder, it is beller that they be Eept whole, and in smali quantities, and poWdered as occasion requires ; coated or green gIass botiles Whicli preclude the agency of light, and stopped close, so asto prevent the accession os moisture, answer practicatly to agreat degree of perfection. The t si Mot, Aster it is dried, ought to be Diable, and stili to retain iis original charactersos bitterness and acrimony. The preparation of the Cassia suis remalias as besore; and there is this advantage in notboiling it, as is somelimes done, that when it is bolled, themucilage of the seeds is also dissolved anu intermixed withthe pulP.
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state os puri ty as to require no purification. Ιf, hoWever, they appear to be impure, holithona in Water untii they sosten, and press themthrough a hempera eloth; then set them by, that the resinous part may Subside. Pour os rand evaporate the supernatant solution by a Nater bath, and to variis the end of the in- spissation mix intimately the resinous Parowith the gummy. The Gum restris, Whicli meli easily, may
they hecome sost enough to be separated frona their impurities by pressure through ahena pen Cloth. Dissolve Storat balsam in recti fied spiritand strain the solution: then distit over thespirit in a gentie heat untii the balsam has
Greater stress is laid than heretosore upon the caresul selection and purity of the gum-restias, and that they obtained in such a state as to require no artificiat process fortheir purification, excepting, indeed, those wsicli are to beapplied to the coarser purpose of external use, and, for this reason, the strained articles are directed to be employed in Mahing plasters, &c. A bladitur is mentioned for straining
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the galbanum, but When the quantity to be prepared is large, a canuas bag is preserabie. With opium these observations hecome more strihingly necessarn because it is intended tohe used in iis crude state, Without as preVious preparation, by solution in rectised spirit and evaporation, as in thesermer Opium puriscatum.