January 29, 1920] 



NATURE 



575 



M. Emile Bei.ot (Revue Scientifique, 1919, p. 686) 

 begins in the happiest manner a discourse on 

 vulcanicity in general and on an artificial vol- 

 canic field of his own manufacture, by reminding 

 his audience of the " big Bertha" that assailed 

 their lecture-hall in the Sorbonne. While the 

 usual height attained by the vigorous projection of 

 volcanic material is 8 km. to 10 km., the dust from 

 Krakatoa rose to 27 km. The experimental volcanoes 

 of the "Bertha" type threw projectiles to a height of 

 30 km. into a layer where atmospheric pressure is 

 reduced to about 1 mm. of mercury, and the hori- 

 zontal range thus rendered possible was as much as 

 120 km. Though the conception was that of a Jules 

 Verne, we must remember that its brilliant realisation 

 was due to the scientific thoroughness of the Germans. 

 M. Belot goes on to show that the lunar crater-rings 

 can be accounted for by normal volcanic projection 

 dans le vide, and he then describes and illustrates a 

 model volcano that derives its water from the per- 

 colation of an artificial sea. 



Ai the end of the article upon the Physical and 

 Optical Societies' Exhibition, in the issue of Nature 

 for January 15, reference was made to the compara- 

 tive absence of simple forms of apparatus for teach- 

 ing purposes. The Zenith Manufacturing Co. showed 

 a representative series of its regulating resistances and 

 controllers of very simple form, and the manager of 

 the electrical department writes to say that a special 

 aim is made at instructional needs. We are aware 

 that the company devotes much attention to the details 

 of rheostats for electrical testing, but this affects very 

 slightlv the point of the paragraph in question, 

 namelv, the desirability of making all apparatus for 

 use in schools and colleges so simple that the principle 

 can be readily understood. 



.^N important paper by Otto Hahn and Lise Meitner 

 on "The Genesis of Actinium " appeared in the Decem- 

 ber I issue of the Pliysikalische Zeitschrift. In 1908 

 Boltwood examined a number of uranium minerals, 

 and found that the ratio of their actinium and 

 uranium contents was constant — a result which indi- 

 cated a genetic connection between actinium and 

 uranium. From these results Rutherford calculated 

 that 8 per cent, of uranium disintegrates along the 

 actinium series. In 1917 Fussier found a value some- 

 what less than 8 per cent., though only three values 

 were obtained, and these vary as much as 60 per 

 cent. St. Meyer and Hess re-e.xamined the question 

 in 1919, and found a constant relation .Ac : U for a 

 set of uranium minerals from various parts of the 

 globe. Hahn and Meitner separate the eka-tantalum 

 [called prot-actinium (Pa) in Germany] from Joachims- 

 thal pitchblende, and compare the total a-ray ionisa- 

 tion from this product with that due to the uranium in 

 the pitchblende. Three methods of separating the eka- 

 tantalum were used, both solutions and residues being 

 examined. The authors find that only 3 per cent, of 

 uranium disintegrates along the actinium series, and 

 the probable error in their results is 10 per cent. This 

 result is in accord with the work of .Antonoff and of 

 Hahn and Meitner on UY, which appears to be the 

 NO. 2622, VOL. 104] 



mother of eka-tantalum. These workers found that 

 the branch ratio of UV to uranium was about 2 per 

 cent. Hahn and .Meitner discuss the available evi- 

 dence, and conclude that the actinium series originates 

 from UII according to the scheme 



U I I-^U V-^Eka-Ta^Ac, 



-UV-^Eka-Ta- 



which agrees with that suggested by Soddy in the 

 Trans. Chem. Soc. (vol. cxv., p. i, 1919). The atomic 

 weight of actinium would thus appear to be 226. 



From the annual report of the Government Chemist 

 for the year 1918-19 (Cmd. 419) it appears that the 

 total number of samples analysed at the Government 

 Laboratory was 289,180. This represents an increase 

 of more than 20, coo compared with the previous year. 

 Owing to the cessation of hostilities and the sub- 

 sequent demobilisation of a part of the combatant 

 forces,' about 16,000 fewer samples were analysed at 

 the central laboratory; but, on the other hand, the 

 partial revival of trade led to a considerable increase 

 in the number of samples of wine examined, and 

 manv more samples also were analysed for the Food 

 Controller and the .\ir Board. Among other items of 

 interest in the report, two unusual instances of the 

 contamination of foods with metallic poisons may be 

 noted. In one case chocolate sweetmeats were found 

 to contain mercury; this was traced to the metal 

 trays used in the processes of manufacture. In the 

 second instance pastry made from self-raising flour 

 contained antimony, due to the use of tartar emetic 

 as a substitute for cream of tartar instead of the acid 

 phosphate of lime intended to be used as a "tartar 

 substitute." 



HoRSE-cHESTNLTS have in recent years been utilised 

 for the production of acetone and normal butyl alcohol 

 by a special process of fermentation. The distillate 

 yields a "mixed oil," of which about one-third con- 

 sists of acetone and the remainder is the butyl alcohol. 

 In the Journal of the Society of Chemical Industry 

 for December 31 Mr. A. Gill gives an account of some 

 experiments carried out at H.M. Factory, King's 

 Lynn, in studying certain aspects of the fermentation. 

 Outstanding features of the operations were (1) froth- 

 ing and (2) slowness; these were attributed to the 

 presence of aesculin or sesculic acid— a bitter, saponin-like 

 substance which, besides producing froth, is apparently 

 inimical to the development of the special micro- 

 organisms employed. The aesculin can be extracted 

 by treatment of the nuts with water or alcohol. The 

 mature nuts contain about 12-5 to 145 per cent, of 

 husk, and immature specimens may have nearly double 

 this proportion. It has been stated that, for successful 

 fermentation, the husk must be completely removed; 

 this was not found to be necessary, though it is an 

 advantage to remove as much as possible, since an 

 excessive quantity retards the fermentation, .\bout 

 19 per cent, of "mixed oil" was yielded by the nuts. 



Lloyd's shipbuilding returns for the quarter ended 

 December 31 last— commented upon by Engineering 

 for January 16— indicate that Great Britain has now 

 regained her foremost position in the world of ship- 



