The elements of materia medica and therapeutics
by Jonathan Pereira, M.D. F.R.S. & L.S.
Fourth Edition, enlarged and improved, including notices of themost of the medicinal substances in use in the civilized world, and forming an Encyclopædia of Materia Medica.
Vol. I.
London: printed for Longman, Brown, Green, and Longmans, Paternoster Row.
1854.Preparation. — Several forms of carbonate of lime are employed in medicine — viz. marble, chalk, precipitated carbonate of lime, and carbonate of lime from animals: Most of these require to be submitted to some preparation before they are fitted for use.
1. Marble; Marmor; Carbonas Calcis (dura); Massive Crystalline Carbonate of Lime; White Marble, E.; Marmor album, D. — This is commonly employed for the preparation of carbonic acid, and for other purposes. White or statuary marble from Carrara should be selected, on account of its freedom from iron. It requires no Preparation.
2. Chalk; Creta; Calcis Carbonas (Friabilis in pulverem subtilissimum trita et elutriata), L.; Creta; Friable Carbonate of Lime; Chalk, E.; Creta, D. — This is found in great abundance in the southern parts of England. It is ground in a mill, and the finer particles are separated by washing them over in water, letting the water settle, and making up the sediment into flat cakes, which are dried in the air. In this state it is called whiting. Two of the British Colleges give directions for the preparation of chalk by elutriation. By this means it is separated from silicious and ferruginous particles. The product is called prepared chalk (Creta praeparata, E. D.) It is usually made up into little conical loaves.
The Dublin College orders of Chalk, lb. j.; Water, a sufficient quantity. Reduce the chalk to a fine powder, and having triturated this with as much water as will give it the consistence of cream, fill the mortar with water, and stir well, giving the whole a circular motion. Allow the mixture to stand for fifteen seconds, and then decant the liquid into a large vessel. Triturate what remains in the mortar, adding as much water as was previously used, and after allowing it to settle for fifteen seconds, again decant, and let this process be repeated several times. Let the fine sediment which subsides from the decanted liquid be transferred to a calico filter, and dried at a temperature not exceeding 212°.
The direction of the Edinburgh College is essentially the same.
Ei kommentteja :
Lähetä kommentti