778 
THE TROPICAL AGRICULTURIST. 
[March i, 1882. 
spontaneous ebullition or evolution of the nitrous 
fumes and benzoic aldehyde vapours. 
If oil of cassia be mixed with oil of cinnamon the 
reaction with nitric acid takes place as with oil of 
cinnamon, but more tardily, according to the amount 
of cassia oil present, and at the end of the process a 
turbid subnatant liquid is seen instead of a clear one, 
as is the case with pure oil of cinnamon. 
Spiri t of nitrous ether can also be used to distin- 
guish between these oils, as it forms a clear solution 
with that of cinnamon, but a turbid one with that 
of cassia. 
Distinction can also be made between the powders 
of cinnamon and cassia, for on shaking cinnamon 
powder with iodine water, a greenish brown colour 
only is seen, whilst cassia powder treated similarly 
imparts a black colour. A better way, however, is to 
make a deeoction of the powder and, when cold, add 
tincture of iodine in excess, when on shaking well in 
a test-tube the froth of the cinnamon decoction is 
distinctly yellow, and that of cassia grey or black, 
and if cassia powder be mixed with cinnamon, the 
characteristic froth of the cassia can be distinctly seen. 
A vote of thanks was passed to the author of this paper. 
Professor Attfield hoped that the author would con- 
tinue his experiments with the view of ascertaining 
the special conditions under which this substance would 
absorb iodine. The absorption of iodine by essential 
oils was a matter involved in a good deal of obscurity. 
The amount absorbed appeared to depend a good deal 
on conditions, and if Mr. Woodland would look into 
those conditions, it was possible he might be able to 
give a good method of distinguishing between these 
substances. 
Mr. Brady said with regard to the employment of 
salt water in the distillation of oil of chinamen he had 
seeo a statement to that effect, in Pereira's ' Materia 
Medica,' and it had been repeated elsewhere, but he 
did not think that salt was employed generally in 
Ceylon.* In the only distilling establishment he visited, 
not only was salt water not used, but the distilled 
water was used again and again, for a manifest eco- 
nomic reason. 
Mr. Greenish said he had heard Mr. Brady state 
that there were several kinds of cinnamon, — eight or 
teu ; he should like to know whether the particular 
kind of cinnamon used in these experiments was 
noticed, because naturally it would have an influence 
on the result. 
Mr. Brady said the different kinds were merely 
planters' varieties ; he did not think anyone could 
deline them. A planter would be able to tell the 
tjifferent sorts, but he did not think there were even 
commercial names for thein. 
Mr. Greenish asked if there were any mode of 
distinguishing them. 
Mr. Brady replied certainly not except by an expert. 
It was more like commercial sorting than botanical 
separation. 
Mr. Greenish said probably it would have an in- 
fluence on the result of the experiment. 
Mr. Brady said practically oil of cinnamon was 
made by the poorer planters, usually half-caste Portu- 
guese, who would not take the trouble either to 
cultivate the shrub properly or to prepare the bark 
for sale as fine cinnamon, and it was quite a ques- 
tion whether growing the finest cinnamon really paid 
the planters so well as using it in the rough con- 
dition as chips for distilling the oil. 
* We remember making enquiries at the instance 
of the late Mr. Henry Mead, and wo were distinctly 
informed that salt never was used. — Ei>. 
ON RED (CINCHONA) BARK. 
By John Eliot Howard, F.R.S., F.L.S. * 
In order to present more definitely the results of 
recent information on this subject, together with 
some suggestions for discussion at the Conference, I 
must (in some sense) begin at the beginning and show 
what I mean by "Rei Bark." 
The limitation of the genus Cinchona to those 
plants which have capsules dehiscent from the base 
towards the apex seems to me most correct and 
natural. I think my friend, Professor Karsten, has 
done good service to quinology, not only by the magni- 
ficent and unique plates and descriptions, in his 
splendid volumes, of the Cinchona cordifolia, and C. 
lancifolia (for instance), but also of the lesser known 
group which he includes to my regret under the 
same head of Cinchonas (Cinchona, sectio IL terasco .) 
The?e have capsules variously dehiscent, though iu 
other respects closely allied to the Cinchona?. I have 
recently met with specimens of the bark of two of 
these, together with leaves and. in one case, very 
well preserved capsules, evidently of the Cinchona 
pedunculata, Karsten. The other I referred, with less 
certainty, to another of his species, G. undata, Krs. 
I was informed that neither of these barks, when 
examined by Dr. Paul, manifested any trace of alkal- 
oid. Is not this a reason (if confirmed) for the 
limitation of the term Cinchona to those plaots which, 
having the capsules dehiscent from the base, also 
possess the medicinal properties from which the name 
is derived? To these alone it seems properly to belong. 
When we come to the definition of species, the 
difficulty of discrimination increases so much that 
some (even of those who are interested in the cultiv- 
ation) seem inclined to throw up rhe whole subject 
in despair, and to believe in unlimited hybridity and 
change, instead of that exact fixedness of type which, 
at all events since the researches of the early Spanish 
botanists, have marked the South American species. 
Pavon especially was very careful in his selection 
of specimens, so that out of forty-one sorts whicu I 
possess of his collection, I am able to recognize at 
least twenty-eight as met with in commerce and as 
like as if they came off the same trees. 
I have thus found amongst the barks of commerce, 
the bark of most of the species described by Pavon 
and his associates, and by Mutis and Zea, exactly 
reproduced with every minute feature. I have had 
the satisfaction of cultiva ing many, and of receiving 
specimens from the native habitats and the adopted 
countries of many others, and my conclusion is that 
fixity of type is the rule, and variability the ex- 
ception. I do not deny that this latter occui* (through 
hybridity) 'n India ; but I agree with the late Dr. 
Weddell in thinking that there is not usually much 
opportunity for this in South America. I can add 
that Dr. Weddell's specimens are admirably true to 
type- • 
Even in India the probability is that many of the 
variations observed are connected with the following 
characteristics, observed first by the Spanish botanists, 
and which I will now briefly explain. 
All the different species of Cinchona (so far as 
observed) exist under different, slightly varying forms, 
of which it seems impossible to say that any one is 
the original species and the others varieties. For 
instance, I havu now, growing from seeds gathered by 
the diligent collector, Robert Cross, two forms of the 
Cinchona cordifolia, from two different localities ; one 
of which, from a place called Coralis Iuza, possesses 
the true cordate form of leaf as represented by 
Karsten iu his plate of Cinchona cordifolia ; the other 
though equally in its marked characteristics the " hard 
Carthagena" or "cordifolia" bark of Mutis, does not 
v Rea,d before~the British Pharmaceutical Coherence. 
