432 



KNOWLEDGE & SCIENTIFIC NEWS. 



[May, 1906. 



Fossil Conifers- 

 Some interesting discoveries of fossil plants from the Port- 

 land beds of Boulogne have been described by Flicke and 

 Zeiller. One is a cone of Scijiioiu of the S. gigtintcit type, 

 which is named S. poiilaiuiica. Previous to this discovery the 

 oldest known cone was S. lusittiiiica, from the Wealden beds 

 of Portugal, which belongs to the living 5. sempervircns type. 

 We have now evidence of the existence of the two living types 

 of Sequoia as remote as the Jurassic period, hence the origin 

 of this genus must be very remote. 



Pine cones were also found representing the two leading 

 groups, Strobus and Pinastcy, living at the present day. One 

 cone, named Piiius saitvagii, is said to closely resemble small 

 cones of the living P. laricio. This discovery in like manner 

 indicates the great antiquity of the genus Piiiiis. 



CHEMICAL. 



By C. AiNsworan Mitchkll, 1;..\. (Oxon.l, F.I.C. 



Lead Poisoning Through Electrolysis. 



A FUESIILY-CUT piece of lead remains untarnished when icept 

 in a closed flask of pure water from which all air has been 

 removed by boiling, but exposed to the simultaneous action 

 of air and water is rapidly corroded, a considerable amount 

 of the metal being dissolved. This action is almost entirely 

 prevented by the presence of the small quantities of salts, 

 notably the carbonates and sulphates commonly present in 

 drinking water, and hence there is usually little risk of 

 lead being dissolved to any dangerous extent by such water. 

 'J"he presence of carbonic acid in the water has a similar 

 protective eflfect, a thin film of insoluble lead carbonate being 

 formed upon the surface of the metal and protecting it from 

 further action. In the case of soft lake waters the small 

 proportion of vegetable matter generally present plays the 

 same part, forming a compound with part of the lead oxide 

 first produced, which acts like a natural varnish to check 

 the solvent effect of the water. For these reasons lead 

 pipes can be used for conve\ing the water for household 

 supply, and have usually been regarded as free from danger ; 

 but a remarkable case recently recorded by Mr. B. Latham 

 points to a hitherto unexpected possibility of poisoning le- 

 sulting from the use of lead pipes. The inhabitants of a 

 cottage to which the water was supplied by the South 

 Hants Water-Works were found to be suffering from lead 

 poisoning, and an examination of the supply-pipe showed 

 that corrosion of the metal had taken place. The cause of 

 this was tinally traced to a leakage from an electric lighting 

 main close by, and a current with a voltage of 1.8 was de- 

 tected between the earth return and the lead water pipe. 

 This had caused electrolysis of the metal, which had been 

 brought into solution in sufficient quantity to render the 

 water poisonous. The correctness of this conclusion w-as 

 established by experiments on a small scale in the labora- 

 tory. 



Industrial Use of Carbon Tetrachloride. 



During the last six months, the use of carbon tetra- 

 chloride as a solvent for fats, has become verv general in 

 Germany, and it will probably, ere long completely super- 

 sede the dangerous carbon bisulphide or petroleum spirit. 

 Carbon tetrachloride is a colourless, mobile liquid, closely 

 resembling chloroform in its general characteristics, though 

 it has no aniesthetic power. It boils at a low temperature, 

 is readily evaporated and condensed, and has the great 

 advantage of being non-intlammable, so that when used 

 for the extraction of fat from bones or other material, the 

 risk of fire is reduced to a minimum. Factories can thus 

 be placed near other buildings, which was out of the ques- 

 tion with the highly inflammable solvents hitherto em- 

 ployed, and the fire insurance companies will accept verv 

 much smaller premiums. Carbon tetrachloride has a faint 

 characteristic odour. Its vapours are stated to have no in- 

 jurious effect upon the health of the work-people, and al- 

 though this point has not yet been definitclv determined, 

 they must certainly be much less hurtful than the vapours 

 of carbon bisulphide, which are very poisonous. Special 



apparatus is required for extracting fat with the new 

 solvent, and this has already been put u[) in a large number 

 of factories. 



The Bacterial Origin of Vegetable Gums. 



Three species of bacteria, discovered by .Mr. K. (jreig- 

 Smith, in the gum and bark of jcaria hincrrata, 

 A. jnnninerris, and SicrcuUa (Ui-crsifolia, respectively, pro- 

 duce gum when grown on suitable culture media, such as a 

 solution of fruit sugar (Isevulose) with glycerine, and traces 

 of asparagine, tannin, and other substancis. Strangely 

 enough, glucose and cane sugar interfcn' with the pro- 

 duction of gum by these bacteria, but on the other hand a 

 new gum-producing bacterium was isolated from the sugar 

 cane, in addition to B. vascularum, the cause of the so-called 

 " Gum-disease." Experiments were made in inoculating 

 plants belonging to the rosacece, with acacia bacteria, and 

 gum was subsequently found to have been produced within 

 the cellular tissue. It is not improbable that this discovery 

 may have a commercial value. In Mr. Smith's opinion, all 

 gums that exude from trees ;ire probably of bacterial origin. 



Gioddu : A Fermented Milk. 



The inhabitants of the mountainous districts of Sardinia 

 cat large quantities of a fermented milk, resembling 

 koumis or kephir. It is j)repared by allowing the milk 

 of the cow, sheep or goat to ferment at a moderately high 

 temperature, either spontaneously or after the addition of 

 baker's yeast, until it thickens into a more or less consistent 

 homogeneous mass, at which stage the fermentation is 

 stopped by plunging the vessel into cold water. The pro- 

 duct, which has a sharp acid flavour, is eaten either by 

 itself or is spread as a butter upon bread. 



GEOLOGICAL. 



By Edward A. Martin, F.G.S. 



Glacial Drift at Moen and Rugen. 



Thk Rev. Edwin Hill, F.G.S., has laid before the Geolo- 

 gical Society the results of his observations on the strange 

 intercalations of drift, which occur in the chalk at the 

 island of iMoen. At first sight the drift appears to be in- 

 terstratified with the chalk, but accepting the theory that 

 the drift was deposited in dislocations in the chalk, it 

 has also generally been assumed that the dislocations were 

 either simultaneous with, or subsequent to, the deposition 

 of the drift. Mr. Hill has, however, examined certain 

 cavities in these dislocations which had been water-worn, 

 and therefore must have been produced before the advent 

 of the drift. It is contended, therefore, that the chalk had 

 been disturbed in pre-glacial times, and the assumption is 

 that there were pre-glacial hills and clitTs similar to the 

 present, with similar clefts and furrows in the cliffs, which 

 were covered in glacial times with a mantle of drift, w'hich 

 is now in course of removal by denudation. This, indeed, 

 seems to be the most natural assumption. .Some geologists 

 have endeavoured to show that the intercalations of drift in 

 the chalk both at Moen and Riigen have been caused by the 

 sheer force of an ice-thrust, ramming such deposits nto 

 the chalk, but, as Professor Boyd-Dawkins remarked, there 

 was no necessity whatever for invoking this agency, and 

 in view of the water-worn condition shown in some of the 

 dislocations, it would seem that the cavities or fissures were 

 caused by earth-movements, aided by the cave-forming pro- 

 pensities of chalk, some time prior to the formation of the 

 drift. 



The Origin of Boulder Clay. 



The discussion on Mr. Hill's paper, and another by Pro- 

 fessor T. G. Bonnev, again brought into sharp contrast 

 the two opposing camps of glacialists, one of which asserts 

 that boulder-clay is undoubtedly the direct product of land- 

 ice, and the other, w'hich asserts with just as little doubt, 

 that this is an impossible solution of the question. Mr. H. 

 B. Woodward and Mr. Lamplugh both jjrofessed their 

 unqualified adherence to the land-ice theory, which, as a 

 matter of fact, has found its way into most modern text- 

 books, whilst Professor Bonney and Rev. Edwin Hill 



