jL'i,v, ion. 



KNOWLEDGE. 



279 



A NEW RADIUM PREP ARA TION.— An extremely 

 active preparation of radium is now produced at the Neulen- 

 bacii radimn works, by means of a combined acid and alkaline 

 fusion process, wliich extracts the radium directly from the 

 minerals in the form of a crude sulphate. According to 

 A. Fischer Xhcin. ZcntralhJatt, 1911, I., 1190) it is possible 

 by this means to treat ten thousand kilogrammes of pitchblende 

 residues and obtain crude radium chloride from them within 

 six weeks, while ores containing ten per cent, and less of 

 uranium oxide, which hitherto could not be economically 

 worked up, may now be used in the preparation of radium 

 compounds. Preparations of radium showing an acti\ity of 

 upwards of three hundred thousand units (Machel per 10 c.c. 

 are now produced at these works. Experiments h.'ue shown 

 that radium enters the human system chiefly by inhalation 

 and not through the pores of the skin. 



ARSENIC IN SEA-WEEDS.— It was shown by Gautier 

 some years ago that arsenic was a normal constituent of 

 certain marine algae, and this has recently been confirmed bv 

 MM. Tassilly and Leroide [Bull. Soc. Chiin., 1911, IX., 63). 

 There are numerous secret medicinal preparations made from 

 algae, including some of the anti-fat remedies, and experiments 

 have shown that the whole of the arsenic will pass into these 

 products. In addition to this, a small proportion of arsenic 

 may be derived from impurities in the other ingredients of 

 these remedies. The proportion of ar.senic in marine algae 

 and mosses of the same species varies but slightly, though 

 there are considerable differences in the case of different 

 species. The following results, expressed in milligrammes per 

 hundred grammes of the algae, containing twenty to thirty 

 per cent, of water, are typical of those obtained ; — Choiidrus 

 crispiis, 0-070; Fiicus vcsiciilusus, 0-010; Corsican moss, 

 0-025; Lainiiiaria digitaia, 0-05Q; L. saccharina, 0-010 ; 

 and L.ricxicaiiHs. 0-010. 



GEOLOGY. 



By Russell F. Gwinnell, B.Sc, A.R.C.S., F.G.S. 



A GIGANTIC GEMSTONE.— A remarl<able crystal of the 

 precious beryl (a mineral which is known as emerald or as 

 aquamarine, according to the particular shade of colour which 

 it exhibits) was recently described in a paper read before the 

 New York Academy of Sciences. This crystal, the largest 

 beryl ever found, was disco\ered by a Turkish miner in a 

 pegmatite vein in the State of Minas Geraes, Brazil. 



The crystalline form was the usual hexagonal prism 

 terminated at both ends by the basal plane. .'\lthough 

 measuring 48-5 centimetres in length, the crystal was so 

 transparent that it could be seen through from end to end 

 when viewed through the basal termination. Its width was 

 from forty to forty-two centimetres, and its weight 110-5 

 kilograms, or well over two hundredweight. It is estimated 

 that the crystal would furnish at least two hundred thousand 

 carats of aquamarine gems of various sizes, when cut. 

 Twenty-five thousand dollars is said to have been paid to 

 the finder for the stone. 



For comparison with this gemstone, it may be interesting to 

 recall the figures for some celebrated diamonds. The 

 Koh-i-Nur, when brought from India, weighed one hundred 

 and eighty-six carats (about one and a quarter ounces) and now, 

 after recutting, weighs one hundred and six carats. Brazil pro- 

 duced the Star of the South, weighing two hundred and fifty- 

 four carats when cut, but while holding the record for beryls, 

 Brazil is easily surpassed by South Africa in diamonds. 

 Thus the Stewart weighed two hundred and eighty-eight carats 

 and the Porter Rhodes no less than four hundred and fifty 

 seven carats (about three ounces) when found. But all previous 

 records were beaten when, in the newly-discovered Premier 

 mine in the Transvaal, the Ciillinan diamond was found in 

 the yellow ground, in 1905. More than three times the size of 

 any known diamond, this stone weighed three thousand and 

 twenty-five and three-quarter carats, or one-and-a-third pounds, 

 and was clear and water-white throughout. The largest of its 



surfaces appeared to be a cleavage plane, so that it might be 

 only a fragment of a nuich larger stone. Purchased by the 

 Transvaal Government in 1907, the CiilUnan was presented 

 to King Edward VII. It was cut, in Amsterdam, into nine 

 large stones and a number of smaller brilliants. 



THE GREAT PROVINCES OR BRANCHES OF 

 IGNEOUS ROCKS.— The old system of grouping the whole 

 assemblage of igneous rocks along one line of variation, from 

 acid through intermediate to basic, is gradually giving 

 wav to a more complex, but apparently more natural, system. 

 In "The Natural History of Igneous Rocks" Harker states 

 that we shall make a decidedly closer approach to the facts if 

 we assume, not one, but two main lines of variations. Each 

 line may be conceived as spanning the interval between the 

 basic and acid extremes, the two diverging most widely near 

 the middle of their course. These great provinces or branches 

 are spoken of as the " Atlantic " or " alkalic " group and the 

 " Pacific " or " sub-alkalic " group. These two great branches 

 of igneous rocks have a well-marked areal distribution, and 

 define two petrographical regions of the first order of 

 magnitude, which stand in relation to the grandest tectonic 

 features of the globe. 



Although in the main the .Atlantic tvpe of rocks occur 

 towards the Atlantic sea-boards both in the American 

 continent and the Eurasian continent, and the Pacific type 

 towards the Pacific sea-board, yet many exceptions occur. 

 Moreover, in a country like Patagonia, where the Pacific and 

 .■\tlantic Oceans come near together the types are curiously 

 interwoven, as in the case cited below. 



In a recent paper, also dealt with below, there is established 

 a third "natural family" of igneous rocks, the spilitic suite, 

 which is clearly distinguished from the Atlantic and Pacific 

 suites. 



In the American Journal of Science for May, Professor 

 L.V. Pirsson refers to" Geologisch-petrographische Studien in 

 der Patagonischen Cordillera ; von P. D. (Juensel." 



TraveUing from Cape Horn northwards along the chains of 

 the southern .\ndes the author throws much light on the 

 geology of this little-known region. 



A feature of interest to petrographers is the occurrence, at a 

 number of places, of alkalic rocks. These consist of intrusive 

 masses of essexite in stocks, exposed domes, and so on. These 

 rocks are composed of purple pleochroic titaniferous augite, 

 brown barkevikite, labradorite and analcite, the latter regarded 

 as secondary, perhaps after nepheline. They are accompanied 

 by a series of dykes of bostonite and camptonite with essexite 

 porphyry, and the author parallels the occurrences with those 

 of Southern Norway, made classic by the researches of 

 Briigger. In other places aegirine-granite-porphyry is found 

 with the essexite. The occurrence of these alkalic types in 

 the sub-alkalic province of the Andes is interesting. 



In the Geological Magazine for May and for June, 1911, 

 Messrs. Dewey and Elett deal with " British Pillow-Lavas 

 and the Rocks associated with them." These pillow-lavas are 

 a group of basic igneous rocks, occurring only as submarine 

 flows and very frequently exhibiting " pillow-structure." The 

 term " spilite " is used to designate these lavas, which are 

 found among Carboniferous, Devonian and Ordovician rocks 

 in Devon and Cornwall. A great variety of types are comprised 

 in the family, and they range from ultra-basic picrite to such 

 acid extremes as quartz-keratophyre, soda-felsite and albite 

 granite. The essential characteristics of the family are the 

 abundance of soda-felspar and the remarkable frequency with 

 which they have been albitised. The albitisation is not due 

 to weathering or to shearing, but it may be grouped as a post- 

 volcanic or juvenile change, produced soon after solidification 

 of the rock. Like the .\tlantic and Pacific igneous suites the 

 spilite group has an intimate connexion with certain types of 

 geological conditions. They are essentially rocks of districts 

 that have undergone a long continued and gentle subsidence, 

 with few or slight upward movements and no important folding. 



