70 



KNOWLEDGE. 



February, 1911. 



an especially striUing similarity between the flowers of such 

 Cacti as Pilocereiis and such Nyniphaeaceae as Victoria 

 and Euryulc. The suggestion ol ;i " Raualian " ancestry for 

 the Cacti, based on the structure of the flowers, is greatly 

 strengthened by the recent work of Miss de Fraine (Ann. Bot.. 

 IQlOi on the structure of the transition region between stem 

 and root in the seedliny- of various members of this order. 

 It was found that in tht so c'acti which have the least modified 

 seedlings — those in v.hich we should expect to find that 

 ancestral characters would be retained — the same t\-pe of 

 transition of the vascular bundle system occurs as in certain 

 Ranunculaceae. Miss Sargant (Ann. Bot.. 1900) showed 

 that this particui.sv zyve of transition structure pointed to the 

 origin of the >ic:-jcotyledon3 from Dicotyledons allied to 

 Kanuncul.iceae. 



CHKMl.S FRY. 



B\- C. .\INSW0RTH Mitchell. B..\. lO.xon.), F.I.C. 



STl- KILISATION OF W.\TER BV MEANS OF 

 ULTRA-VIOLET RAYS.— The use of ultra-violet rays for 

 the effective sterilisation of large quantities of water has been 

 made the subject of several recent patents, and processes 

 based upon the principle have been adopted in many places. 

 It has been demonstrated by Messrs. L'rbain, Seal and Feige, 

 iCuniptcs Rend.. 1910, CLI., 770.) that the most important 

 factor in this method of sterilisation is that there should be 

 uniform exposure of the particles of water to the source of 

 light. In some types of apparatus this condition is attained 

 by enclosing the mercury vapour lamp in .a box with three 

 quartz sides, round which the water is made to flow in a 

 semi-circular trough in such a way that it moves alternately 

 towards and away from the lamp, which forms the centre of 

 the semi-circle. Again, in the apparatus constructed by 

 Urbain and his collaborators, the water is made to circulate in 

 a spiral within a cylinder about two-and-a-half yards in 

 diameter, the opening into which is concentric with its axis. 

 The water being forced into this cylinder at a tangent, whorls 

 round so as to leave a nearly vertical cavity in the centre, and 

 within this is suspended the lamp. Under these conditions, 

 the maximum distance of the water from the source of light is 

 about forty-two inches, and the minimum distance about 

 three-and-a-half inches, while the period of exposure is about 

 three minutes. The positive electrode of the lamp is composed 

 of aluminium, coated with a thin layer of iron, while the 

 negative electrode consists of carbon. The yield of sterilised 

 water obtained from an apparatus of this Uind ranges from ten 

 to fifty cubic metres per hour, the average quantity being 

 about twenty metres. A sterilising plant based upon this 

 principle has been erected at N'euilly-sur-Marne, and gives a 

 supply of sufficiently sterile water at an expenditure of twenty 

 watts per cubic metre. 



THE WATER OF GREAT SALT LAKE.— An interest- 

 ing series of analyses of water from Great Salt Lake is 

 published by Messrs. Ebaugh and MacFarlane (/. hid. Eng. 

 Chain., 1910, II, 4541, showing the variations in the amount of 

 saline constituents during the last forty years. During the 

 four years of drought ending in 1904, the level of the water fell 

 to such an extent that the idea of the lake becoming dry was 

 seriously entertained ; but after the succession of wet years 

 since that date, there is more likelihood of the surrounding 

 country becoming flooded. These extremes are reflected in 

 the composition of the water at the different periods, the 

 specific gravity and the total solids showing an enormous 

 decrease since the close of the dry period. Thus, in October. 

 1903, the water had a specific gravity of U2206, and contained 

 3,iiS'36 grammes per litre of total solids, whereas in October, 

 1909, the specific gravity was ri561, and the total solids were 

 only 242'25 grammes per litre. The composition of the water 

 varies at different periods of the year, the proportion of 

 dissolved salts being greater in the autumn. 



A NEW METHOD OF PREPARING ARfiON.— A rapid 

 method of obtaining large quantities of argon is described by 

 M. G. Claude in a recent issue of the Coniptcs Rend.. 

 (1910, Vol. CLI, 752). Oxygen obtained in the liquefaction 

 of air is used as the source, for it has been found that the 



chief impurity in the oxygen is argon, the volatility of which is 

 intei-mediate to that of oxygen and of nitrogen. To separate 

 the argon, which then often exceeds three per cent., the oxygen 

 is absorbed by means of copper, and the nitrogen by magnesium. 

 For this purpose the gas is passed through a red-hot copper 

 tube charged with reduced metallic copper and copper filings, 

 and on leaving this passes through a red-hot iron tube 

 containing magnesium powder. Lastly, it is passed through a 

 tube of silica containing copper oxide to absorb any hydrogen 

 derived from moisture in the oxygen or in the copper. From 

 eight to twelve litres of pure argon may be obtained by means 

 of this apparatus in about two hours, after which the copper 

 becomes spent, and must be regenerated by a current of 

 hvdrogen. 



'the SOYA BEAN INDUSTRY.— The importance of 

 soya beans as a new commercial product may be gathered 

 from the fact that during the year 1909, upwards of five 

 hundred thousand tons were imported into this country from 

 China, and were utilised in the manufacture of oil and of seed 

 cake for cattle. Prior to 190S only small consignments had 

 been imported, but the great scarcity of fats and oils required 

 for the manufacture of soap induced the manufacturers to 

 make experiments with every kind of oil, and as soya bean oil 

 was found well suited for the production of soft soaps and, in 

 admixture with other fats, for hard soaps, it speedily estab- 

 lished its present position. The beans, which are used in 

 China and Japan in the preparation of soy sauce and other 

 food products, yield, when pressed, about 10 per cent, of a 

 vellow oil, which has weak drying properties and possesses 

 many points of resemblance to cotton seed oil. The oil is 

 used for food in China, and has been tried for the same 

 purpose in this country, .attempts have also been made to 

 employ it in place of linseed oil in the manufacture of paints 

 and linoleum, but its inferior drying properties h.ive prevented 

 its application in this direction. The beans contain about 

 forty per cent, of protein substances and twenty-three per 

 cent, of carbohydrates, and the residue from which the oil has 

 been expressed is thus a valuable feeding stuff'. Unsuccessful 

 attempts have been made to acclimatize the soya bean in 

 Germany, but the plant has already been introduced into 

 West Africa and the southern part of North .America, with 

 every prospect of success. 



GEOLOGY. 



Bv Rfssi;i L V. (iwiXNELL. B.Sc. A.R.C.S.. F.G.S. 



A CENTRAL AFRICAN GLACIER of Triassic age is 

 dealt with by Messrs. Ball and Shaler in the Journal of 

 Geology, November-December, 1910. The glacial features 

 occur in the Lubilache formation of the Belgian Congo (better 

 known as the "Congo Free State"). This formation consists 

 mainly of alternating beds of sandstones and shales of Triassic 

 age. It is concluded from the evidence that a glacier or 

 glaciers pushed in a tongue down the present valley of the 

 Lualaba Ri\er ; from the fact that large boulders probably 

 dropped by icebergs are found at least two hundred feet abo\e 

 the base of the formation, it is believed that long after the 

 glacier had retreated toward the south, glaciers still existed to 

 the south-east. This glacial epoch must therefore have been 

 of a considerable duration. 



The glacial features presented are : — 



(1) Striations having the characteristics of glacial striations, 

 on pebbles in the basal conglomerate of this series, indicating 

 morainal origin. 



(2) The tongue-like form of the basal beds and the character 

 of this conglomerate, including the size of the boulders, the 

 lack of assortment, the patchy arrangement of the material and 

 the preponderance of boulders of local origin. 



(3) Erratic boulders, presumably dropped by icebergs, 

 occurring in shales of this series. 



(4) Probable glacial scratches, crescentic gouges and smooth- 

 ings on the surfaces of older rocks upon which the Lubilache 

 was laid down. 



IGNEOUS ROCK COMPOSITION.— Several petrologists 

 have calculated, from large collections of published analyses, 

 the " average composition " of an igneous rock. In some 



