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Show 260 PRICKLY SALTWORT. PRICKLY SALTWORT. Pore Kaur. (Kali Purum. E.) Take of water of pure kali, one gallon: Evaporate it to dryness; after which let the salt melt on the fire, and pour it out. The principal thing to be attended to in this operation, is to conduct the evaporation so rapidly that the ley shall not absorb any carbonicacid from the atmosphere. As long as any water of solution remains, the ebullition is evident, and the evapora tion is to be continued until it cease. The heatis then to be increaseda little, which renders the potash perfectly fluid, and gives it the appearance of an oil, when it is ready to be poured out, either on a slab, as directed by the colleges, or into iron moulds, such as are used for the melted nitrate of silver. The potash prepared according to these directions is sufficiently pure for medical use, but is not fit for chemical experiments. We can, however, obtain it perfectly white and erystallized, according to Berthollet, by adding to the ley, when evaporated so ed far that it would assume the consistence of honey, if permitt carbothe of ird one-th to to cool, a quantity of alcohol, equal g nate of potash operated on, mixing them together, and lettin poured be to then is e mixtur ‘The them boil a minute or two. grainto a glass vessel, and corked up, when the impurities will dually subside, partly in a solid form, and partly dissolved in water. ‘The supernatant alcoholic solution is then to be evapo- crust, rated rapidly, till its surface become covered with a black poured be which is to be removed, and the liquid below is to subinto a porcelain vessel, when it will concrete into a white stance, which is to be broken in pieces, and immediatelyexcluded from the action of the air. nat A less expensive way of obtaining potash perfectly pure is tl of Lowitz before mentioned. MEDICAL USE. of 4 Potash is only used as a caustic, or to form solutions is inconyenient, known strength; and even its use as a caustic from its being so quickly affected bythe air, and from its rapid deliquescence, which renders it apt to spread. CA usTiC, Porasn with Lime, rormerry Minper Common E.) (Potassa cum Calce, olim Causticum Commune Mitius. Takeof solution of potash, any quantity; 261 Evaporate in a covered iron vessel till one third remains; then mix with it as much new-slakedlime aswill bring it to the consistence of pretty solid pap, whichis to be kept in a vessel closely stopt. Dr; c Lime wirn Pure Karr. G (Calx eum Kali Puro, L.) Take of quicklime, five pounds and four ounces; water of pure kali, sixteen pounds: Boil away the water of pure kali to a fourth part; then sprinkle in the lime, reduced to powder by the affusion of water. Keep it in a vessel closely stopt. x Caustic Kart wira Lime. (Kali Causticum cumCalce.) Evaporate caustic ley to one-third; then add powdered burnt hme till it form a sufficiently thick mass, whichis to be kept in well-closed vessels. The addition of the lime in these preparations renders them less apt i managed, and milder in their leliquesce, more easily . to deliquesc i operation, 4 > or Porasu. Ion . Carsonate (Carbonas Potasse. E.) Let impure carbonate of potash, called in English pearlashes, be ~ eae a crucible, and brought to a low red heat, that the oily Impurities, if there be any, may be burnt out: then tritu- a, an pio weight of water, and mix them thoroughly “aangal fter the feces have subsided, pour the liquor aun: z — iron pot, and boil to dryness, stirring the salt nd of the process, to prevent its sticking to the ee Preparen Karr. (Kali Preparatum. L.) Take of potashes, two pounds ; eeta st ae water, three pints: Bseeeraneta hours, that the neutral salts hs cryst Mi ¥ Fis hi ba it out thete liquor, and boil boil away, aw if asslow ; aL ‘hole ofofthe the whole fire, “ie with ae the y stirring, Jest the salt should adhere tothe pot. COns 7 Silchar thlike m the ashes of any kind of eee is purified impure kali from The sz : be salt may be prepared fromtartar, which should burnt til ame iit becomes ‘nt till of an ash colour. |