. Public health and preventive medicine. culated from this, isexpressed as a percentage of the tea, and is termed the total soluble contains tannic acid, thein, volatile oil, soluble albumin, dextrin, glucose,pectin, and the soluble salts. Average amount, 36 per cent. Soluble a*lt.—If the total soluble extract be incinerated and weighed,the amount of soluble ash is forthcoming. Average, 3 per cent. Thein or caffein.—This is calculated from the nitrogen contained inthe soluble extract after subjection to the following process. Some of thesoluble extract is diluted with distilled wate
. Public health and preventive medicine. culated from this, isexpressed as a percentage of the tea, and is termed the total soluble contains tannic acid, thein, volatile oil, soluble albumin, dextrin, glucose,pectin, and the soluble salts. Average amount, 36 per cent. Soluble a*lt.—If the total soluble extract be incinerated and weighed,the amount of soluble ash is forthcoming. Average, 3 per cent. Thein or caffein.—This is calculated from the nitrogen contained inthe soluble extract after subjection to the following process. Some of thesoluble extract is diluted with distilled water, the albumin precipitated withcopper sulphate and caustic potash, and the fluid filtered. A portion ofthe filtrate is used for Kjeldahls process (p. 174), which is then is 1 part of nitrogen in 3-46 parts of thein, and the average amountof the latter in tea is 2 to 4 per cent. Tannic acid.—Make an infusion and add solution of gelatine whichprecipitates the tannic acid. The sediment is collected, dried and Fig. 78.—a, Tea leaf, x 2 diameters, b, Sectionof tea leaf showing idioblasts, x 160 diameters.(After Pakes.) 250 GENERAL SANITATION and 100 parts of ii contain 40 parts of tannic acid. Tea contains 10 to 12per cent, of tannic, acid. Adulterations and their Detection.—Other Leaves, such as those of theslue, the willow, and various other shrubs and trees, may be added to presence of the idiohlastic cells already mentioned is the best meansof distinguishing, as they are peculiar to tea leaves. Exhausted tea leaves,doctored with catechu and gum, may be added as an adulterant, and maybe detected hy their want of aroma, by the presence of catechu, and by theincrease of total ash and diminution of soluble ash and soluble extract. Coffee is the kernel of the fruit of the Oaffea ardbica, and it is firstroasted and then ground, in order that an infusion may be prepared from and masted coffee beans differ in their composition, th
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectprevent, bookyear1902
