Juty 18, 1912] 
NATURE 
Sus) 
Pétersbourg, vol. xli., p. 221, with English version 
on p. 265). His optical observations show that 
divergent fibres are not essential in cone-building ; 
but he regards the cones as essentially a type of 
spherulites. References are made to English 
instances. 
R. C. Burton describes an interesting occurrence | 
of crystallised kaolin replacing fossil shells in Coal- 
measure shales. He refers _the mineral to the re- 
moval of part of the associated clays, which were a 
mixture of hydrated silicates; the unstable members 
have disappeared in waters containing carbon dioxide, 
leaving a pure kaolinite to be deposited in the hollows 
left by the solution of the shells (Proc. Univ. Durham 
Phil. Soc., vol. iv., 1911, p. 24). 
Riebeckite, zgirine, 
cates are critically discussed by C. H. Warren and 
C. Palache in their account of certain pegmatites at 
Quincy, Massachusetts (Proc. Amer. Acad. Arts and 
Sci., vol. xlvii., 1911, p. 125). Incidentally (p. 147), 
doubt is thrown upon the eutectic origin of graphic 
granite, since the Quincy examples contain 60 per 
cent. felspar and 40 per cent. quartz. The same 
authors (Amer. Journ. Sci., ser. 4, vol. Xxxi., p. 533) 
investigate the ‘Chemical Composition and Crystal- 
lisation of Parisite’’ in connection with its occur- 
rence in the Quincy pegmatites. Parisite is the rare 
fluo-carbonate of calcium and the cerium earths. It 
is suggested that Flink’s synchisite from Narsarsuk, 
in Greenland, first described as parisite, is a true 
parisite, its additional molecule of CaCO, being 
possibly an impurity (p. 545). Riebeckite and other 
silicates from the same rocks are here again 
described. 
F. Zambonini, in his ‘‘Contributo allo studio dei 
silicati idrati’” (Soc. reale di Napoli, Atti Acad. 
Sci., ser. 2, vol. xiv.,-No. 1), seeks to show, by a 
series of determinations of water lost at various 
temperatures, that our knowledge of the composition 
of hydrated silicates is still far from complete. The 
treatment of the zeolites is of special interest, and 
the author modestly regards this quarto memoir of 
127 pages as a step towards future work by others. 
He concludes that minerals may contain a variable 
amount of water in solid solution, which accounts 
for the different analytical results. This reminds us 
of the remarks made by Allen and others on pyrrho- 
tine, above referred to. 
Zambonini also deals largely with silicates, but at 
the same time with a number of other minerals, in 
his monumental treatise entitled ‘‘ Mineralogia 
vesuviana” (ibid., No. 6). He has here brought 
together results from a wide range of literature. On 
p. 56 he gives reasons for doubt as to the composition 
of Scacchi’s melanotallite, and proposes the new 
name idromelanotallite for the green mineral derived 
from it on exposure to the air, which has the com- 
position CuCl,.CuO.2H,O. This memoir, with a 
good index, occupies 368 pages. 
Eero Makinen (Bull. Comm. géol. de Finlande, 
No. 26, 1911) describes in German a method for the 
determination of alkalies in silicates by means of 
calcium chloride, which he finds to be simpler than 
that of Lawrence Smith. The process is carried out 
in an ordinary platinum crucible. 
W. T. Schaller’s ‘‘ Mineralogical Notes” (U.S. 
Geol. Survey, Bull. 490, 1911) contains a revision of 
the two new borates, hulsite and paigeite, 
Alaska. 
ferric molybdate, and not molybdenum trioxide. 
Turning to petrography, H. Dewey and J. S. Flett 
review the British ‘‘Pillow-lavas” (Geol. Mag., 
IgII, pp. 202 and 241), those interesting greenish 
andesitic rocks which are so often associated with 
radiolarian cherts. They show their albitic character, 
NO. 2229, vol. 89] 
from | 
Molybdite (p. 84) is shown to be a hydrated | 
and place them in a family of igneous rocks, the 
“spilitic suite," which is distinct from Harker’s 
Atlantic and Pacific suites. Albitisation has arisen 
in them through the action of water containing soda 
and silica in solution. They are associated with dis- 
tricts “that have undergone a long-continued and 
gentle subsidence, with . . . no important folding.” 
It may be pointed out, however, that the extreme 
uncertainty as to what rocks belong to the Atlantic 
and Pacific types make a third type at present un- 
desirable in connection with them; G. Steinmann, 
moreover, has recently connected rocks of this spilitic 
nature with regions of intense earth-movement and 
overfolding (Ber. nat. Gesell. Freiburg-i.-B., Bd. 
| XVi., 1905, p. 64). 
and other rock-forming sili- | 
R. A. Daly again attacks the problem of the rocks 
rich in alkalies in a paper on ‘‘ Magmatic Differentia- 
tion in Hawaii” (Journ. Geol., vol. xix., 1911, p. 289). 
He believes that volatile substances rising through 
the volcanic vent carry up alkalies with them from 
the cauldron below, and so bring about a differentia- 
tion. This is supported by the experiments of 
Giorgis and Gallo on the removal of soda from 
Vesuvian lavas by a current of carbon dioxide. L. V. 
Pirsson (‘Geology of New Hampshire, No. v.:, 
Petrography of Tripyramid Mountain,’ Amer. Journ. 
Sci., ser. 4, vol. xxxi., I911, p. 431) points out a 
region of alkalic syenites for which the theories of 
Jensen and Daly as to the absorption of sediments 
will not hold; but Daly’s suggestion made in the case 
of Hawaii might serve also in New Hampshire. It 
is refreshing, however, to find Pirsson remarking, 
| amid the current ingenious theories of differentiation, 
that his syenite may perhaps be regarded as an 
intrusion separate from the associated gabbro. 
In ig10 F. Berwerth carefully examined the 
surface-features of meteorites and of the curious 
glassy bodies .known as moldavites, and concluded 
that the latter showed no signs of fusion from pass- 
ing through our atmosphere, but merely etchings due 
to chemical corrosion in the spots where they are 
now found (Tscherm. Mitt., Bd. xxix., p. 12). 
G. P. Merrill has independently examined the molda- 
vites and allied ‘“‘tektites’’ (Proc. U.S. Nat. Mus., 
vol. xl., 1911, p. 481), including ‘‘bullitonites’’ and 
‘““australites,”” and observes that the moldavites are 
comparable to fragments of true volcanic glass which 
have been etched by corroding vapours or solutions, 
while none of the ‘‘tektites’’ show the characteristic 
flutings of meteorites. The origin of these scattered 
glassy pellets, occurring in superficial deposits, re- 
mains unsolved. 
In the Proceedings of the American Philosophical 
Society, vol. I., 1911, p. 519, J. J. Stevenson con- 
cludes an elaborate study of literature on the forma- 
tion of coal. Peat is here considered, and the sixty- 
four pages devoted to its characters, origin, and 
occurrence form an important work of geological 
reference. In dealing with buried forests, the author 
criticises the wide acceptance of the drift-theory as a 
means of accounting for coal formed of the remains 
of trees. 
In conclusion, we should note that G. W. Grabham 
has described the improved form of petrological 
microscope made under his supervision for the Sudan 
Survey by Swift and Son, of London (Min. Mag., 
vol. xv., p. 335). It is a development of the well- 
known Dick model. The author then discusses 
illumination, and gives a new explanation, which he 
attributes to E. M. Anderson, of the “white line 
effect’ due to the juxtaposition of two substances of 
differing refractive index. This expianation covers 
the commonly occurring cases where the surface of 
junction of the substances is inclined to that of the 
rock-section. GoeAW TELE: 
