31 S 



KNOWLEDGE. 



August, 1911. 



experiments with tliat natural ferroso- ferric oxide, and. by- 

 fusing it in an oxidising flame witli quartz sand and sodium, 

 lias succeeded in reproducing the black enamel. 



The richness of the lustre is probably increased by the 

 presence of a trace of manganese in the magnetite. A similar 

 enamel is found upon the Egyptian pottery, and it is probably 

 trom Egypt that the GreeUs derived their knowledge of the art. 



PROPERTIES OF .A.LUNDUM.— .A fused form of 

 alumina is now extensively used under the name of 

 " .-Mundum " in the manufacture of crucibles and other \essels 

 for which a refractory material is needed. .According to 

 Mr. L. E. Saunders iAiiici: ElcctrocJiciii. Soc. .'\pril. 19ll), 

 the commercial product is usually a white crystalline 

 substance containing less than one per cent, of iron oxide and 

 other impurities. There is also a red-brown variety contain- 

 ing about five to six per cent, of impurities, and melting at 

 about 2,000 to 2.050° C. or about 50° lower than the white 

 alundum. The specific gravity of the latter is 3-93 to 4-00, 

 and its heat conductivity is from three to four times as great 

 as that of fire clay. It resists the action of aqueous acids 

 and alkalies and is only slightly attacked by fused alkali 

 carbonates. Crucibles of alundum may be used for melting 

 metals with as high a melting point as platinum, though they 

 are too porous to be used for melting slags. .\ cement for 

 lining furnaces is also prepared from alundum. and has the 

 advantage of not melting or combining with carbon at 

 temperatures below 1,950 C. Bricks of alundum have also 

 been used instead of silica for the roofs of electric furnaces. 



THE TR.ANSFORM.ATION OF R.\DIL'M.— Professor 

 Rutherford, to whom w^e owe much of our knowlege of radio- 

 active bodies, gives a most interesting survey in the Journal 

 of the Society of Chemical I ndiistry i\9\\. XXX, 659), of 

 the principal results regarded from the chemical point of view. 

 'l"he three types of rays emitted by radio-active substances are 

 classified as a. ii, and 7 rays in accordance with their pene- 

 trative capacity and effect upon a magnetic field. The a rays 

 possess only slight penetrati\e properties, and are readily 

 stopped by a metal plate. They appear to consist of streams 

 of particles identical with the gas helium. The ji rays are 

 more penetrating and more easily deflected by a magnetic 

 field, and are supposed to be identical with electrons ; while 

 the 7 rays are exceedingly penetrating, are not deflected by a 

 magnetic field, and ha\e apparently properties analagous to 

 those of the Rontgen rays. 



Uranium is to be regarded as the first parent of the radium 

 family. It is decomposed so slowly that about five thousand 

 years would be required for half of it to be transformed 

 into an element termed Uranium X, with an atomic weight of 

 230-5. This emits ,i rays, and is transformed into ionium, 

 the direct ancestor of radium. Coming to radium itself, a 

 continuous disruption takes place with the liberation of 

 a rays (helium) and the formation of a new element, the 

 radium emanation, which appears to be one of the inert 

 gases. This radium emanation, in turn, breaks up with the 

 expulsion of an a particle or helium atom and the formation 

 of a new very unstable element. Radium A, which is rapidly 

 transformed into another metallic element. Radium B, decom- 

 posing in twenty-six minutes, with the expulsion of ;i ravs, into 

 Radium C. The latter breaks up into Radium D, which in turn 

 yields ;uccessi\ely Radium E and Radium F. The element 

 polonium has been identified with Radium F, and there is some 

 evidence that the element formed in the decomposition of 

 polonium is lead. The atomic weights and the nature of the 

 radiations emitted by these successive elements are summarised 

 by Professor Rutherford in the following table : — 



Radial ion. .Aloinic Weight. 



Uranium... ... ... 2a ... ... 238-5 



Uranium X ... ... .i ... ... 230-5 



Ionium ... ..■. ... la ... ... 230-5 



Radium ... ... ... la ... ... 226-5 



Emanation ... ... la ... ... 222-5 



Radium .\ ... ... la ... ... 218-5 



Radium B ... ... )i ... ... 214-5 



Radiatinn. Atomic Weight. 



Radium C ... ... fa ... ... 214-5 



Radium D -i 210-5 



Radium E ,i 210-5 



Radium F la 210-5 



End product — 206-5 



(lead?) 

 Many interesting details are given of the methods of 

 examination employed in the investigation of these bodies, 

 but, as Professor Rutherford points out, " the process of 

 transformation cannot be influenced to the slightest degree 

 by any chemical or physical agency. \\'e are only able to 

 watch these atomic processes, but cannot control them." 



GEOLOGY. 



By G. W. TvKRK[,i,. A.R.C.Sc. F.G.S. 



THE PROBLEM OF THE SCOTTISH HIGHL.\Ni)S. 

 — .A. new interpretation of this classic region is put forward by 

 Professor J. W. Gregorv, in the Transactions of tlic Glasgo'^- 

 Geological Society, Vol. XIV (1910).. The most disputed 

 points are the age of the Ualradian System, and which is the 

 top or bottom of its long succession of deposits. In regard to 

 the first question. Professor Gregory believes the Dalradians 

 to rest unconformably upon the Moine Gneiss, an extensive 

 flaggy formation which stretches from the Central Highlands 

 to the Pentland Firth ; but from certain evidence in Islay, they 

 are probabl>- older than the Torridon Sandstone. Among the 

 Dalradians themselves, the Loch Lomond Gneiss is believed 

 to be the oldest. This is succeeded to the north by the Loch 

 Tay, Ben Lawers. and Blair .\tholl series, and the Schichallion 

 Quartzite, .AH these rest unconformably upon the Moine 

 Gneiss to the north and north-west, with the exception of the 

 Loch Lomond Gneiss, which does not appear to come into 

 contact with the Moine anywhere. Two further series, the 

 Ben Ledi and the .Aberfoyle, occur to the south of the Loch 

 Lomond Gneiss, and appear to rest unconformably upon that 

 formation. The great band of quartzite in the Central 

 Highlands is, under this arrangement, the j'oungest rock in 

 the Dalradian System, with the possible exception of the 

 .Aberfoyle Series. It rests unconformably upon the black 

 schists of the Blair .Atholl Series, and forms great cakes which 

 have been carved into bold mountain masses such as 

 Schichallion and Ben-y-ghlo. Two other horizons of quartzite 

 or quartz-schist occur below the Schichallion quartzite. These 

 separate groups have often been confounded together, and 

 also with some portions of the Moine Gneiss, but they can 

 usually be distinguished by their petrographical characters, as 

 well as by their stratigraphical position. Professor Gregory 

 concludes his paper with a series of suggestions as to useful 

 research by Glasgow geologists on the south-western 

 Highlands. 



NEW MEMOIRS OF THE GEOLOGICAL SURVEY 

 OF SCOTL.AND — The three interesting memoirs on Edin- 

 burgh, East Lothian, and the Glenelg district, recently issued 

 by the Scottish Geological Survey, form %ery important 

 additions to our knowledge of Scottish geology. The first two 

 are new editions, but they are entirely new works, and their 

 superiority to the first editions, issued forty or fifty years ago, 

 is a measure of the advance in local geology during that period. 

 The Edinburgh memoir is a volume of 445 pages, and contains 

 numerous beautiful plates, as well as a geological map of 

 .Arthur's Seat, This classic hill, vvhich renders the local 

 geology as picturesque as Edinburgh itself, is fully described, 

 and the description, together with the geolo.gical map, has 

 been issued as a separate pamphlet at the price of sixpence. 

 The oil-shale field of Central Scotland comes within the area 

 described in this memoir. This industry has been developed 

 since the issue of the first edition, and the new information 

 made available by mining operations has rendered necessary 

 great changes in the geology of the region. 



The East Lothian Memoir describes rocks ranging from the 

 Silurian of the southern uplands to the Coal measures disap- 

 pearing under the Firth of Forth. The district includes the 



