416 
NATURE 
[JANUARY 25, 1917 
tent of the soil on which the walking fern was found 
was about 4 per cent. The occurrence of chalk-loving 
plants therefore does not necessarily indicate the pre- 
sence of lime in the underlying rock strata, except 
in cases where circumstances preclude the accumula- 
tion and decay of vegetable matter, and the resulting 
accumulation of lime in the soil. This investigation 
throws some light on the question of rhododendrons 
growing on limestone rocks referred to in NaTurE 
of November 2, 1916 (p. 171). 
Mr. Leonarp Hawkes, in a paper on “The Build- 
ing-up of the N. Atlantic Tertiary Volcanic Plateau" 
(Geological Magazine, 1916, p. 385), shows that the 
numerous red partings in the basaltic series of Ice- 
land are due to layers of glassy volcanic dust. Similar 
dust is often carried over wide areas of the lava-deserts 
by wind-storms at the present day. The colour is 
due to oxidation, which here seems unconnected with 
any tropical climatic cause. The connection of a red 
layer with underlying decomposition of the basalt, as 
is the case in the great red zone in Co. Antrim, has 
not been proved in Icelandic observations. 
GEOLOGIsTsS as well as mineralogists will always 
find new suggestions in Mr, W. T. Schaller’s 
‘*Mineralogic Notes."’ In Series 3 (Bull. 610, U.S. 
Geol. Survey, p. 106, 1916) a new member of the 
melilite group is described under the name of Velar- 
defiite, and the whole group is then discussed. A 
graphic tabulation of analyses indicates that melilite, 
which has hitherto occupied a very uncertain position, 
is an isomorphous mixture of Akermanite and sarco- 
lite. On p. 138 am illustrated note deals with the 
giant crystals of spodumene in the pegmatites of the 
Black Hills, S. Dakota. These are often 30 ft., and 
may be 42 ft., long, and are about 4 ft. in diameter. 
THE restrictions on the export of coal from the 
British Isles and its rising price are having serious 
results in Scandinavian countries. The deposits of 
coal at And6, in the Vesteraalens, are of small import- 
ance, but are the only ones in Norway. Lately, however, 
Norway has sought to overcome her difficulties by the 
purchase from an American syndicate of vast coal- 
fields in Spitsbergen. The coal, although of Tertiary 
origin, is of good steam quality. Lignite has been 
known in Iceland for some time, but so far has had 
no economic value. However, according to La Nature 
(December 16, 1916), a Danish company is now extract- 
ing large quantities at Stalfjall, in the north-west of 
the island, both for local use and for export to Nor- 
way. The, lignite occurs in bands of clay among 
basaltic strata, and its average depth is only six 
metres. Iceland should have no difficulty in export- 
ing large quantities of this lignite provided it proves 
sufficiently useful to be in demand. It is said to occur 
among the same basalts in the Farée Islands. 
In the Geographical Journal for December (vol. 
xIviii., No. 6) Mr. R. C. Mossman has an important 
paper on the physical conditions of the Weddell Sea. 
The paper is based’ on the work of the Scotia and the 
Deutschland, the only two ships which had scientific- 
ally explored the Weddell Sea previously to the Endur- 
ance, the work of which is, of course, not yet avail- 
able. The observations from the South Orkneys ob- 
s€rvatory have also been utilised. In meteorology the 
most striking results are the correlations which Mr. 
Mossman has been at pains to work out between tem- 
perature and pressure conditions in the Weddell Sea 
and those in other parts of the southern hemisphere, 
and even in Jeeland. For the last twelve years the 
August and September temperatures at the South 
Orkneys have been a direct index to the temperatures 
at Kimberley, South Africa, during the three months 
NO. 2465, VOL. 98] 
following, and there is also a marked sympathy be- 
tween the South Orkneys barometric pressure in De- 
cember and the height of the River Parana at Rosario, 
which is, of course, dependent on the rainfall over 
southern Brazil, and this is related to the barometric | 
pressure. In December there is a marked tendency 
for high pressure to the south and south-east of Ca 
Horn, and Mr. Mossman suggests that when 
Graham Land lobe of the Antarctic anticyclone is in- 
tensified the pressure over the interior of Brazil is 
correspondingly diminished, and vice versa. More 
remarkable perhaps is the pronounced opposition be- 
tween the barometric pressure at Stykkisholm, Iceland, 
and the South Orkneys. Data from 1902 to 1914 show 
no break in this sequence. ir 
Tue nature of the particles of mineral matter which 
become embedded in the lung tissue in cases of miners’ 
phthisis has been determined by Drs. W. Watkins- 
Pitchford and J. Moir by microscopical examination 
in polarised light of specially prepared sections of sili- 
cotic lungs, their results being given in Publication 
No. VII. of the South African Institute for Medical 
Research (Johannesburg, 1916). 
field is suggestive of a starlit sky, but in ordinary 
circumstances only the larger particles are so visible. 
The particles have the form of irregular and angular, 
more or less elongated, chips or flakes, the majority — 
being less than 2 microns in diameter, and very rarely 
reaching as much as 14 wp. The smaller flakes, when 
lying flat, have not sufficient thickness to react on 
polarised light, and they are only seen as streaks 
when they are set edgeways (the light then traversing 
a longer path through the doubly refracting medium). 
Further, the particles are obscured by the tissue in 
which they are embedded. The method previously 
adopted of destroying the lung tissue by means of 
hydrochloric acid and potassium chlorate also resulted 
in the destruction of some of the mineral matter. This 
objection is overcome by treating the sections with 
nitric acid or strong hydrobromic acid. Such prepared 
sections were compared with preparations of the dust 
collected from the air in the Rand gold mines and 
of the powder obtained by finely grinding the rock 
(“‘banket"’) from these mines. The mineral species 
identified include quartz (constituting more than 99 per 
cent. of the particles), sericite-mica, rutile, zircon, 
and tourmaline, and perhaps chlorite. Similar par- 
ticles of mineral dust were also detected in the tissue 
of normal lungs; for example, the two lungs of a 
farmer, who had never worked in the mines, were 
estimated to contain a hundred thousand million par- 
ticles of foreign mineral matter, whereas in the lungs 
of a miner affected with the disease the estimate 
reaches the appalling number of twenty to thirty 
millions of millions of such particles, 
Tuat the zodiacal light owes its origin to the re- 
mains of comets captured by Jupiter was the theory 
proposed fairly recently by Fessenkoff. <A criticism of 
this theory is now given by G. Armellini in the Atti 
dei Lincei, xxv. (2), 9, in which it is shown that one 
formula: arrived at by Fessenkoff is in direct opposi- 
tion to an analogous one given by Schiaparelli in 1871. 
The author is, however, led to accept a modification 
of Fessenkoff’s theory in which collisions between 
the meteoritic material of the captured comet play an 
important part. : 
In the Atti dei Lincet, xxv. (2), 10, Mr. G. K6rner 
and Dr. A. Contardi describe the properties of the 
sixth form (eta) of trinitrotoluene, recently discovered 
by them, as announced in a previous number of the 
Atti (xxiv. (1), 9, May, 1915). In arriving at the pre- 
paration of this new trinitrotoluene it was not possible 
to have recourse. to direct nitrification, and it was 
In polarised light the - 
