June 1, 1904.] THE TEOPICAL AGRICULTURIST. 
825 
COPRA IN SAMOA. 
The report on tha t rade ofSiinox for the year 
1903 by the Acting; Vic3-Coasul hx? been issued 
from the Foreign Office. 
MrTroodsaya the nativa popalatioa of th3 whola 
group, Bisc and West Samoa, may hs stated as from 
68,000 to 39,000. The white popalatioa numbers from 
400 to 500 ; the half-castes GOO to 700. Copra, at 
present the only important S imoan export, was sub- 
ject to a serious decline ia price at the bsginnin^ of 
the year, and as the value of this article at the date 
of the report was only £9 153 per ton of 2,211 lb f o b 
steamer, when, last ye-ir, it was eagerly sought for 
at £14, trade suffered accordingly. The Simoins, too, 
were holding for higher rates, they being professedly 
ignorant that prices are subject to downward fluctua- 
tions. Rates would have been much lower, were it 
not for the Sydney market, which ordinarily ab- 
sorbed Samoaa copra to the extent of 3,000 to 4,000 
tons yearly. The excitement about cacao cultivation 
has, Mr Trood says, much subsided in the last 12 
months, small capitalists having satisfied themselves 
that although this industry can bil^ery advantageous- 
ly carried on by large capitalists, it may not 
necessarily be the same in their case. Mr Trood 
adds :—" The Labour Question is of more importanoe 
than any other, imported labour being an absolute 
necessity. Kanakas from other islands are much 
preferred for plantation work. Their average wage 
at present is £2 per month with board. A few months 
since nearly 300. Chinese coolies were brought here 
from Swatan, where Governor Self during his journey 
to Europe last year called and arranged the matter 
with the Chinese authorities. They cost the planter 
£2 lOs per month. This includes board and their 
passage money to and from China. So far, it is said, 
they have given satisfaction. 
♦ 
BISCOVEEY OF THORIUM IN CEYLON, 
A LEADING EXPERT'S OPINION. 
Sir, In the beginning of February 1 bought from 
Mr Holland 5cwt. of the mineral described by Frof. 
Dunstan in last week's Nature, Ic crystallises in 
cubes, and the density is substantially that found 
by him. Mr Tjrer, of the Sterling Chemical Works, 
Stratford, was so kind as to promise to work it 
up for me, and the process is still being carried on. 
1 had hoped to have positive and definite results 
to communicate before describing its constituents, 
but the publication by Prof. Danstanof an analysis, 
and his statement that he is still engaged in its in- 
vestigation, makes it necessary to write this letter. 
The mineral, when heated alone, gives ofi 3'o 
cubic centimetres of helium per gram ; fused 
with hydrogen potassium sulphate, the amount 
is increased to 9 '5 cubic centimetres. From this 
source I have already stored about 12 cubic 
feet of pure helium extracted in Mr Tyrer's works. 
It was at first believed that the mineral was rich 
in uranium, but different specimens contain only 
from 8 to 12 per cent of th'it element, agreeing in 
this respect with the analyses published by Prof, 
Dunstan. Next, the other main constituent was 
believed to be zirconium, but the high density of the 
mineral rendered this improbable. An analyst of 
high standing, whose daily business it is to analyse 
minerals of this kind, returned 82 per cent of 
zirconia as a constituent; the percentage of thorium 
was triiiing — nniler 1 per cent. The mineral con- 
tains practically no thorium ; this has been 
repeatedly confirmed in my lulioratory. Nor does 
it contain any appreciable amount of serium, 
anthanum and didymium, The oxalate is almost 
completely soluble in excess of ammonium oxalate 
— a reaction which excludes thorium and the 
cerium group, but which points to zirconium. The 
equivalent of the elements of the oxalate group, 
which I at first took for zirconium, excludes the 
presence of any large quantity of zirconium, 
although that element is undoubtedly present. 
Fractionation shows that the oxalate precipitate 
(the portion soluble in ammonium oxalate) gives 
equivalents between 2.5 0 (the most insoluble 
portion of the double sulphate) and 44 7 (the most 
soluble portion) ; by far the major part of the ele- 
ment has the last-mentioned equivalent. The 
separation of this portion is now being carried out 
with large quantities of material ; several hundred- 
weights are being worked up. 
Assuming that the element is a tetrad which ia 
probable from its behaviour, it undoubtedly 
possesses an equivalent approaching the highest 
number (44-7), and for this there is a gap in the 
periodic table between cerium and thorium ; one 
at least of the elements present (supposing that 
there is more than one present) will probably have 
an atomic weight of about 177, preceding tantalum 
(182'5) in the horiz lutal row of the periodic table. 
I am at present engaged in mapping the spectrutu 
of this new body or bodies. 
As for the radio-activity, the mineral was 
brought in the hope that it would have a high 
content of radium. There is a trace of radium 
present — due, no doubt, to the spontaneous change 
of the uranium which the mineral contains. But 
the radio-activity due to this source is certainly 
not 5 per cent of the total. 
The period of decay of the emanation appears to 
point to the presence of a radio active element 
closely resembling thorium X, The half value is 50 
or 51 seconds, and while this is not quite the time 
for the decay of thorium emanation, it very nearly 
approaches it ; at present the balance of evidence 
appears to point to the presence of an element 
closely resembling thorium, but not identical with 
it. The total radio activity, moreover, is much 
greater than can be accounted for by the suppo- 
sition that the one consists of pure thoria. Within 
the limits of a letter I am obliged to omit many 
more characteristics of this curious ore which 
have been ascertained, but I hope soon to be 
able to publish more definite results : as it is, I 
regret to have been obliged to tell an imperfect 
story. 
I should like to conclude by acknowledging the 
great assistance given me in this work by Mr 
Tyrer and by my students, Messrs Gimingham and 
Le Rossignol. William Ramsay. 
Aature. 
LANDOLPIIIA RUBBER: ITS COLLECTION 
AND PREPARATION. 
[by MR. M. T, DAWE, BOTANIC GARDENS, ENTEBBE. 
The Landolphias, which yield the best rubbers 
of commerce, belong to an important order of 
plants, viz. Apoci/naccae. Several species occur in 
Uganda; they are found chiefly in the forest belt 
that borders the Lake, or in forests near swamps 
and rivers ; forests disconnected from well-watered 
districts as a rule contain less rubber vines, and 
in some eases none at all. All the species are 
climbers and are dependent on trees for their sup- 
port. L florida (Mulimu) seems less particular 
than the other species, and is often found on low 
