368 REPORT—1905, 
Determinations of tannin have been made in the barks of several trees and in 
other vegetable products. The bark of the Cape beech yielded 15:96 per cent. of 
tannin. In Acacia saligna and Acacia pycnantha the percentages ranged from 
19 to 22 and from 18 to 26 per cent. respectively. The rhizome of Rumex 
cordatus contained 11 per cent., and the ’Ntolwane tuber 14:4 per cent. Experi- 
ments showed that it was possible to raise the tannin in Acacia pycnantha from 
26 to 34 per cent. by judicious slitting. 
The advisability of growing sugar beets upon svils containing relatively much 
potash but little lime is suggested. 
It has been found that Cape vines grafted upon American stocks bear far 
more luxuriantly than when grown upon their own roots,.and hence lead to a 
more rapid exhaustion of the soil—an important fact to remember in connection 
with the reconstitution of colonial vineyards by means of grafted vines. 
The Cape climate has been found to have a marked effect on the milk produced 
by thoroughbred Friesland cows born in the Colony. Although the Frisian strain 
be kept pure, acclimatisation appears gradually to produce an all-round increase 
in the milk solids. 
Much attention should be paid to the indigenous plant poisons and drugs. 
Poisonous principles have been obtained from Tichilia Drege’, E. Mayer, and 
Mesembryanthemum tortuosum, LL, An alkaloid resembling quinine therapeutically, 
but differing from it chemically, was extracted from the Umjela, or quinine tree 
( Tabernemontana ventricosa), which abounds in the Transkei. DBuphane toaicaria, 
Herb., and Acocanthera venenata, Don, contain poisons which exhibit characteristic 
chemical reactions, and a poisonous resin was found in Polygonum tomentosum. 
An unknown poison has also been discovered in Ornithogalum thyrsoides. Alkaloids 
and glucosides, as well as oils, resins, and compounds of the aromatic series in 
abundance, await discovery and employment. 
Several analyses of Cape fishes have been made, with a view to glean informa- 
tion as to their nutritive value. From Vhyrsites atun an oil was extracted of a 
lower viscosity than sperm oil, but, as regards gumming, similar to rape oil. As 
far as experiments have gone, this oil seems suitable for light work at low 
temperatures. 
In various parts of the Colony clays have been found, some of which compare 
well in chemical composition with the best fireclays—Stourbridge, for example ; 
others may be used for similar purposes to the Torbay paints. Besides these, 
there are keolins resembling the Cornwall ‘ china clays,’ 
Mineral pitch has been observed in samples brought from the Knysna and 
Barkly East districts. The latter is a limestone possessing all the characters of 
asphalt rock, and is said to occur in large quantities, 
Curious occurrences of free chlorine were reported, due apparently to natural 
hypochlorites. 
The water question on the Government railway system is of great moment, 
and immense loss, direct and indirect, is annually caused to the administration 
through the unavoidable employment of bad water. 
There is a vast field awaiting research on all these subjects, and others 
besides, and an urgent necessity exists for finding means to carry on many 
investigations of the highest importance. 
3. On an Important Characteristic of Cape Wines. 
By Huinricu Trerz, Ph.D., M.A. 
The several varieties of vines cultivated at the Cape and known as Green 
Grape, Stein Grape, red and white Muscadel Grape, Hlanepot Grape, and Pontac, 
appear to have been introduced shortly after the occupation of the Cape by the 
Dutch. 
These varieties were brought from the Rhine and from France at the end of 
the seventeenth century, and have in the warm climate of the Cape in course of 
time considerably changed their original character. 
