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Materia Medica.

part II.

sapidity. The large proportion of gluten in wheat flour ren-ders it fitter for this purpose than any other kind of flour.During the process a large quantity of carbonic acid gas isevolved, which swells up the mass, and gives it the sponginessand lightness that characterize well-baked bread." For thepurpose of baking bread a heat of 488° is required.

Starch is inodorous and insipid; in white columnar masseswhich are easily reduced to powder. It is insoluble in alco-hol, ether and cold water; but in the latter it falls to powder.Boiling water dissolves it, forming an insipid, inodorous semi-transparent, opaline, gelatinous-like paste, which becomes br'it-tle and opaque, when spread out in a dry air; but when ex-posed, without being spread out, it separates into a wateryfluid, and an opaque paste; sours, and becomes mouldy. Al-cohol precipitates starch white and tough from its solutions ;acetate of lead and infusion of galls also throw it down, but theprecipitate formed by the latter is re-dissolved by heating theliquid to 120°. Although potash dissolves starch, yet the so-lution of it is not altered by potash, carbonate of potash, norammonia: but a solution of potash in alcohol, and a solutionof sulphuret of potash in alcohol, both produce precipitates.From the products obtained from distilling starch per se, itappears to be a ternary compound of carbon, oxygen, and hy-drogen.

Medical properties and uses — The utility of bread as an ar-ticle of diet requires no particular notice: as a medicinal agentit is used for forming poultices, cataplasms, and for givingbulk and form to very active medicines which require to begiven in minute doses, in the solid state, or as pills. Whentoasted and infused in water, it gives a pleasant flavour to thefluid, and renders it more acceptable as a diluent in febrilediseases, and as the ordinary beverage of the dyspeptic. Starchis less nutritive than bread, hut is perhaps more digestible.It forms the greater part of the nutritive matter of the differ-ent farinaceous substances which are in general use as thediet of the sick, such as sago, salep, tapioca, arrow root, andgruel, which are only different modifications of starch. Thesolution of starch is employed medicinally as a demulcent;but as it is very readily acted on by the stomach, it cannot beof much service in involving acrid matters in the intestines,when taken by the mouth. In the form of enema, however, itis often and advantageously used for allaying the effects of acrid

1 The method of makinc leavened bread was probably invented by the Egyptians 5for it appears that the Israelites \se\e acquainted with it after they sojourned in Es^ypt,but not before It was known to the Greeks during the Trojan war: but the u r .e oi\tast or larm was discovered by the ancient Gauls.