CINNAMON REGION OF EASTERN AFRICA. 339 
color, showing that they contain a blue coloring matter in- 
soluble both in water and spirit. 
If these facts are considered sufficient to establish the 
existence of indigo in litmus cakes, it follows that the ana- 
lyses of litmus hitherto published cannot be relied on, and 
in fact are of little value, since none of them make any men- 
tion of indigo as a constituent of litmus. 
My examination of litmus cakes leads me to infer that 
they consist essentially of five parts: 
1. Lichen-blue. 
2. Indigo-blue. 
3. Organic remains (portions of the lichenous tissues.) 
4. An ammoniacai salt, separable from the cakes, by sub- 
limation, in the form of carbonate of ammonia. 
5. Mineral or earthy matter (chalk, &c.) 
The lichen-blue is the peculiar coloring matter which 
renders litmus valuable as a test. It is soluble in water and 
in spirit, is reddened by acids, but does not become green 
by the addition of alkalies. — Pharm. Journ. 
i 
ART. LXX XII.— ON THE CINNAMON REGION OF EASTERN 
AFRICA. 
By Mr. W. D. Cooley. 
The eastern angle of Africa was at a very early period 
named, from its exchangeable produce, Aromata; and from 
the Straits of Bab el Mandel to Cape Gardafui, we then 
meet in succession the Regie Myrrhifera, R. Libanolophora, 
and R. Cinnamonifera, In the classic ages of Greece and 
Rome, the belief was general that most spices were derived 
from Arabia Felix or Yemen, the country of the Sabaeans, 
in a later age called Hymiarites, or Homerites. But a care- 
