66 



taste and a strongly alkaline reaction, is almost insoluble in water, 

 readily soluble in alcohol, ether, and acids. 



Deutoeatecliuic Aci(l=:CATECHLic Acid. 



Dextrin = C12 Hio Oio. "With this name a gum-like product, 

 obtained from starch iinder the agency of diastase or acids, is 

 designated, which differs from common gum by turning the 

 polarised light strongly to the right, while gum arabic turns it to 

 the left, and by yielding no mucic acid with nitric acid. Neither 

 are its solutions clouded by subacetate of lead, chloride of iron or 

 silicate of potash. Consequently it ought not to be coloured (red) 

 by iodine, a fact which must here be particulaily stated, because 

 such a property is sometimes ascribed to D., but which only 

 takes place when it is contaminated with a kind of modiüed 

 starch, as indeed often occurs with different commercial kinds 

 of D. As is the case with gum, D. seems not to be wanting in 

 any plant; yet it is often confounded with the former on account 

 of its great similarity, and j^erhaps because it is constantly asso- 

 ciated with it. — Its isolation and quantitative estimation corre- 

 spond with that of gum. It will be easy from the above to 

 distinguish it; but not when it is associated with gxim, because 

 it is distinguished fi-om the latter more by negative than by 

 positive qualities, except in the behaviour towards polarised light, 

 which is entirely ojjposite to that of gum and becomes modified, 

 when the two substances are mixed together. 



Dextro«-lucose= Grape Sugar. 



Diastase. Nitrogenised ingredient of the germinated barley 

 (Hordeum vulgare) which possesses in a high degree the property 

 of converting starch into dextrin and sugar. It is obtained when 

 the contused malt is macerated with cold water, pressed, the 

 liquid mixed with a little alcohol, the filtered liquor completely 

 precipitated with alcohol, the deposit washed, redissolved in water, 

 precijiitated with alcohol, and lastly dried on a glass-plate at a 

 very gentle heat. After triturating, it forms a white, amorphous 

 l)0wder without taste or smell ; dissolves in weak, not in strong 

 alcohol; is not precipitable by subacetate of lead. The aqueous 

 solution when heated to the boiling point becomes cloudy aud 

 inactive; it even becomes decomposed on keeping and turns acid. 



Diea Fat obtained from the dica-bread (the seeds of Irwingia 

 Earteri). Similar to Cacao fat ; fuses at 30° to 33°, contains 

 laurin and myristin. 



Digitaletill = C44 Has Ois. (According to Waltz, the 

 Digitalin of Homolle). In Digitalis pui-purea and D. lutea, and 

 doubtless several congeners; ingredient of the crude digitalin. 

 The leaves are reduced to powder and freed from chloi'ophyll by 

 ether. They are then exhausted with alcohol, and the tincture is 



