BEVERAGES 115 



as a percentage. Coffee gives a remarkably constant 

 percentage of 24, and chicory a mean percentage of 70, or 

 a standard difference of 46, so that percentage of coffee = 

 100 (70 percentage of extract found) -f- 46. A third 

 method is to calculate the percentage of soluble ash and 

 then calculate adulteration on this basis. 



TEA. 



Tea is the prepared leaf of the shrub, Camellia thea, 

 which grows in China, India, Ceylon, and Japan. It is 

 nearly always blended to a standard quality and flavour 

 by mixing two or more kinds of leaves. When the leaves 

 are baked (to dry them) immediately after picking, green 

 tea results ; but if first allowed to ferment and then baked, 

 black tea is obtained. The chief constituents of tea are 

 moisture, caffeine, tannin, albuminous matters, ethereal 

 oil, gum, dextrin, fat, wax, chlorophyll, woody fibre, etc. 

 Tea is now rarely adulterated, since it is examined by the 

 Customs authorities, and samples found to be adulterated 

 are not allowed to be imported. The usual adulterants 

 were foreign leaves (sloe, willow, elder, hawthorn, beech, 

 etc.), sweepings, tea dust, clay, mineral matter, ground 

 olive stones, catechu, gum, starch, and exhausted tea- 

 leaves. 



Moisture. Dry 5 grm. of sample to a constant weight. 

 Varies from 4 to n per cent ; average 6 per cent. 



Total Ash. Ignite dried tea at lowest possible tempera- 

 ture to get a grey, not a green ash. Varies from about 

 5 per cent to 7 per cent, averaging about 6 per cent. 



Insoluble Ash. The total ash after weighing is washed 

 on to a filter-paper, and thoroughly extracted with about 

 400 c.c. of very hot water, the washings being carefully 

 preserved. The filter-paper is then dried, ignited, and 

 weighed, and the weight of filter-paper ash being deducted, 

 the amount of insoluble ash is known. Varies from 2 per 

 cent to 4 per cent, of which less than i per cent is 

 insoluble in HC1. 



Soluble Ash. Deduct amount of insoluble ash from 

 total ash, and result is soluble ash. Varies from 2-8 to 4 

 per cent, but should be at least half the total ash. If the 



