26 
NOVEMBER 28TH, 
MICROSCOPICAL MEETING.—MR. W. H. SMITH ON 
THE “INGREDIENTS OF UNFERMENTED DRINKS 
—TEA, COFFEE, AND COCOA.” 
After describing the tea plant and the processes through which the 
leaves had to pass’in the manufacture of black and green tea,—the 
latter really yellowish or brownish in colour,—he remarked that the 
colouring matter used to give a green appearance to the green tea of 
commerce consisted of facing powders, composed of Prussian blue, 
turmeric, sulphur, gamboge, and Chinese clay. Unfaced tea when 
analysed consisted of a Volatile Oil, Theine, and Tannin. The 
Volatile Oil was not present in the fresh leaves, but was developed 
during manufacture. The headaches and giddiness to which tea- 
tasters were subject, and the attack of paralysis to which the packers 
were liable, were all said to be caused by this oil; and, in fact, the 
Chinese would not use tea until it was at least a year old and had 
probably lost much ofits oil. Tea contained about one per cent of this oil. 
Theine was the active principle to which tea owed its great value as a 
drink. The teas of commerce contained on an average about two per 
cent. Theine appeared to have the remarkable property of stopping 
the waste of tissue, and thus acted indirectly as a highly nutritious 
body. It produced wakefulness, and hence was employed by students 
who wished to continue their work late at night. It had also properties 
which rendered it very useful in many cases as a medicine. It was a 
very remarkable fact that the three substances—tea, coffee, and cocoa 
—which were used as beverages all over the world, to the exclusion of 
almost everything else, should all contain alkaloids, one of which was 
identical with theine, and the other nearly so. 
Besides the substance used to colour tea, the leaves of other 
plants, viz. sloe, hawthorn, alder, willow, plane, oak, poplar, beech, 
elm, and others had been detected as adulterations, while a tea deno- 
minated by the Chinese Zze Tea, made from tea dust, sweepings, sand, 
and other substances, mixed with gum and coloured, was extensively 
imported. In this country old tea-leaves had been re-dried, mixed 
with other substances, and sold as new tea. The microscope would 
detect adulteration, because certain characteristic markings of the 
epidermis of true tea-leaves were invariably wanting in its substitutes. 
Coffee, the roasted seeds of an evergreen shrub, like tea, contained 
three active principles—a volatile oil, Cafzone, an alkaloid, Cafetne, 
and Oaffeic Acid, Caffeone might be obtained by distillation, and 
