October I, 1888.] THE TROPICAL 
AGRICULTURIST. 
263 
Examination or Nodular Stones Obtained by 
Tbawwno off Colombo, by E. J. Jones, a.r.b.m., 
Geological Survey of India. 
[We had not heard of the following paper con- 
tributed to the proceedings of the Asiatic [Society 
of Bengal, until wo found it quoted into the records 
of the Geological Survey of India. First remarking 
that it is interesting to learn that close to Colombo 
the sea deepens to 075 fathoms, or 4,050 feet, wo 
would suggost that volcanic matter which has 
come lloatmg from Krakatao and its neighbourhood 
into our seas in large quantities may, to some ex- 
tent, account for the abnormal constitution of the 
nodular stones ? — Ed.] 
The following account* of Ur'so stones is reprinted 
from the Journal of the Asiatic Society, Bengal, as 
being of moro direct interest in these Records : — 
" The nodules were obtained during a trawling 
operation oft Colombo in water of (375 fathoms, and 
are stated to have been found associated with sand 
and mud, whiuh formed a hard calcareous crust at 
the bottom of the sea, uud a small quantity of which 
was forwarded with the specimens. 
"The stones are irregularly rounded, and vary in 
shape from almost Bpherical to roughly cylindrical 
with rounded ends. Too specimens received varied 
in size from 1—4 inches in length and l : j — j inch in 
thickness. Externally, they are rough ami mostly 
have one or two small excrescences of the size of 
a pm's head, and a few small pittiugs of about 
the same size ; the colour is dirty light grey. 
'• On breaking them opeu, the fractured surface 
has much the appearance of an ordinary slate without 
the cleavage, and is of a much darker c ilonr than 
the exterior, lluuniug along the oentrxl line of a long 
cylindrical one which 1 broke open, there is a narrow 
vein of a brownish colour. 
"A microscopic examination of a thin slice shewed 
merely u confused mass of aggregates resembling in 
their structure that of splnorulites, such as occur in 
the BO-oaUed.sphseruiitic lavas, with the remains of Fora- 
roinifera ami fiadiolaria disseminated throughout the 
mass. With ordinary light, Utile is to be seen except 
moro or loss radiating librous aggregates, but as soon 
as the section is observed between crossed Nicol's prisms 
the whole field is seen to be covered with little dark 
■Oases with their limbs parallel to the planes of the 
prisms, and, on revolving the stage, tho limbs of the 
crosses keep the same orientation whilst the section 
revolves. 
" It is when thus observed that the aggregates are 
seen to bo entirely distiuct from ono another, as 
each cross keeps to its one aggregate, and the crosses 
do not overlap; so that, by revolving the stage, the 
limit of each aggregate can be determined by tracing 
tho path of tho outer end of one of tho limbs of the 
crosses. 
" In the volcanic rocks in which this structure is 
known, it appears to bo due to incipient crystalliza- 
tion in a glassy mass ; and at first it might be supposed 
that theBO masses were of igneous origin. This idea, 
however, is uuteuaole on account of the remains of 
Foraminifora (ot several species, tho most easily re- 
coginsed of which arc the globigoriiim) uud Kadiola- 
ria which are sparsely scattered through the mass, 
and, in somo cases, enclose a spbioruiitic aggregate. 
An indeterminate greenish substance, which probably 
cousists of glaaoonite, is also seen scattered through 
tho mass. The only difference that can be detected 
between the ceiilr.il vein and the portion between it 
ami tho exterior is that the aggregates in the 
central voin are much larger and tho colour 
brown instead of green, and that it is uuacled on 
by hydrochloric acid, which dissolves out somo calcic 
• Natural History Notes from M. M.'s Indian Marino 
Survey Steamer " Invo.-t igator," Commander Alfred 
Carpenter, H. N., Commanding. No. 5. On some No- 
dular Stones obtained by trawling off Colombo in U7*i 
l'atnnnn ol Water.— Hy U.J. Jones, a. ic. s. m., Uoo- 
logieal Survey of India, Jouro. Asiatic Society of 
Bengal, LV I., Pari II, No. J, ls37. 
carbonate from the other portion. As mentioned 
by Mr. Daly in his letter forwarding the nodules, 
these are very heavy, having a sp. gr. of 377 at a 
temperature of 30° C. as against water of 4° C. A 
qualitative analysis shewed the nodules to consist 
in great part of baric sulphate together with small 
quantities of calcic and strontic sulphates, small quan- 
tities of calcic and magnesic phosphates, aluminic 
silicate, calcic carbonate, and traces of iron, sodium, 
and manganese. 
" Not having the time to devote to a complete 
quantitative analysis, I made, in order to arrive 
at an approximate estimate of the proportion of 
baric sulphate present, a determination of the sul- 
phuric acid. An average sample from two of the 
nodules powdered and dried at 100° C. gave 82-5 per 
cent, of baric sulphate, the whole SO2H02 being cal- 
culated as SOaBao". "This result is, however, 
of course too high, as a small quantity of the 
SO2H02 is combined with Ca. and Sr. in 
tho form of calcic and strontic sulphates, though, 
from the results of the qualitative analysis, it is pro- 
bacy not much too high ; and wo may, 1 think, safely 
take 75 per cent as the percentage of bari<- sulphate 
present. In order to see whether the material was 
derived from tho mud in which the nodules occur, and 
which also contained Foramiuifera, I made a qualita- 
tive aualysis of the mud, and found it to consist 
mainly of aluminic silicate, with small quantities of 
calcic carbonate, some iron, and a trace of manganese ; 
there was also a trace of an alkaline earth which was 
not removed by boiling with hydrochloric acid and 
subsequent washing, but this, on spectroscopic ex- 
amination, shewed itself to be lime. 
" In spite of the negative result of the analysis of 
the mud, I am inclined to think, from the presence 
of the Foraminifera both in the mud and enclosed 
in the nodules, that the latter have been formed at 
the bottom of the sea eitner at the spot where they 
were found or at no great distance therefrom, though 
it is diflicult to imagine how the material was obtained; 
but it is possible that a careful aualysis of a larger 
quantity of the mud would reveal a trace of Barium, 
for sea-water contains a slight trace of this element. 
"I cannot at present call to mind any instance of 
sphiurulitic structure occurring without the aid of heat. 
"In volcanic lavas and in artificial glasses, it may 
be regarded as concretionary, or as resulting from in- 
cipient crystallization or devitrification around certain 
points or nuclei. Tho nuclei when they exist consist 
either of a granule or a minute crystal or crystallite, 
but most commonly no nucleus is discernible.* 
"In this case, however, it would seem, that it must 
bo due to slow segregative action; and, baric sulphate 
being very slightly soluble in water, the deposition 
would bo very slow and may have been to some extent 
crystalline, at any rate sufficiently so to produce the 
same effect as incipient crystallization from a glassy 
mass." 
A SCHOOL OF ENGINEERING FOR CEYLON. 
The receipt from the Madras Government of the 
report on tho working of the Madras College of 
Engineering during 1887-8 suggests to us the 
necessity that exists for such an institution in 
Ceylon. Wo have got a Medical College in Colombo 
which has proved a marked success, and wo do 
not seo why a college fur training young men as 
engineers should not be equally successful. There 
are plenty ol trained ollicerB in the Public Works 
Department whoso services could be utilized as 
leclurors, while there is the Government factory 
available for the practical part of the training. We 
arc suro that thoro aro many young men who would 
bo only too glad to have the opportunity thus offered 
them of becoming titled for an engineering career 
Kulloy's Study oj RookSj p. lbJ. 
