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Sulphuric acid, by Weight, sive
This sali is noru for the first time directed to be prepared ; in the Pharmacopoeia of 178I, the ordinary sali os commerce Was merely purified by solution and crystalligation. That Sali is never pure, but contains iron, copper, and a litile lead, ali of which may however be separated by a plece of metallicainc immersed in the solution, whicli, by iis stronger assinityto Sulphuric acid, Will distoclge these other metuis. It has upon the whole, however, been judged to be more advantageous and certain, and not so much more eXpensive as to bean Object os importance on that account, to direct the mode
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of iis preparation. Perhaps the best method to procure themetes, Whicli possesses some malleability, in pieces smallenough to be eastly acted iapon by the acid, is to divide thezinc by pouring it when melied into mater. Sulphat os ginc crystalliZes by evaporation in laur-sided prisms terminated by
four-sided pyramids. It is os a transparent White colouriwith a strong metallic astringent iaste. Ιt dissolves in two and a half paris of water at GO', and in much less of boilingwater. It is not solubie in alkohol. It consists of oxyd 20, acid 40, water 40, and is exposed to air loses a sinali portionos the lalter and rather emoresces. Some chemisis have Ialely considered ii as a supersulphate.
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Oleum sulphuratum, P. L. I 787. Balsamum sulphuris simplex, P. L. II15.
Tahe of Washed Sulphur, tWO OunCC8. Olive Oil, a Pint. Having heated the oti in a very large iron pol, adit the sulphur gradu ally, and stir themixture after each addition untii they have
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The object of this preparation is to render tho sulphur solubie in Water, Which these proportions so managed willeffeci; the former process Was deficient in the directions forfusing the mixture, Whicli is necessary. A perfeci chemicat sulphuret os potass Would require the use of potass, not iis subcarbonate) but this is not necessary for the purposes of pharmacy. These preparations are almost devoid of smellwhen in a dry state, but On eXposure to Water in any Way, as to a moist air, they decompose it, and the formation offulphuretted hydrogen is denoted by iis peculiar smeli; theyshould there re be kept in stopped botiles. It may be Proper to State, hoWeVer, that this preparation is unsit forthe separation os sulphuretted hydrogen gas, on account Ofthe carbonic acid it contains, and that such gas may be best obtained stom sulphuret of iron and sulphuric actu muclidilutin
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165 ed. Froni the colour of the compound resulting Dom theunion os potass and sulphur it has been called Hepar sulphuris
Flores sulphuris loti, P. L. I 787.
Sublimed sulphur prepared upon a large Scale containssome sulphuric acid, whicli is evident to the taste, and thesedirections are intended to remove it. It is farther pro-Per, that sulphur, When Washed, should be kept in closed vesseis rather than in an open drawer; for in the lalter Siluation iis superior surface manifestly becomes acid on Iong keeping.
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Sulphur praeeipitatum, P. L. 1787. P. L. II45. I ac sulphuris P. L. 1720.
In the Pharmacopoeia of 1745 a sulphuret os lime was formed, or rather an hydroguretted Sulphuret, as it Wasprepared in Water like the process noW adopted, and the sulphur precipitaled Dom the solution by sulphuric acid ; in that of 1787 sulphuret os potass Was decomposed by the Same acta. The insolubie sulphate of lime could scarcely bewashed out Dom the former, and the sulphate os potass notwithout dissiculty from the lalter; both there re containedadmixtures of the se salis, to whicli they oWed a good dealos their White appearance. The present precipitate, Dom
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phur, but it will be stili much Whiter than sublimen sulphur, cither Dom iis more minute division, Or Some Other cause notweli ascertained. Ιt Will, hoWever, differ in no other respectfrom sublimen sulphur, and has probably for this reason been omitted in both the Edinburgh and Dublin Pharmacopoeias ; but as this circumstance of colour gives it an advan lage in the composition Os Oinimenis, So as a refinement, rather than necessary agent in practice, it is here retai d. The proportion os lime is diminished in the present edition, Dom three poundS to tWO.
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The collection of vegetabies, in generat, is not the imme diate province of the apothecary; but Witti respect to indigenous planis, the direction os circumstances relative to their periods of perfection, modes of preservation, and botanical CharacterS, comes Under his superintendance ; and of thesehe must be able to judge When they are offered to him bycollectors. A fuller statem ent is there re introduced than was formerly given, and it is much to be wished that an attention to it Was extended to those of our colonies abroad, which furnisti articles of Μateria Medica, as there is reasonto hope that the supply of our markets Would thera be more uniform in quality than it is at present. It is necessary that vegetable matters should be dried as quicEly as possibie, provided the heat applied be not so great as to destroy their colour, and for Whicli purpose eXposure to a temperature of IOO' is
fully sussicient; it is best applied by the artificiat heat of stoves, or a heated room, in whicli the influence of light is avoided.
commonly seen in the parceis of Conium Whicli are broughthom the neighbouring country to London. The rejectionos those vegetable matters Which have been hept longer than