596 



SCIENCE 



[N. S. Vol. XXVIII. No. 722 



almost exactly to the amount theoretically 

 predicted by Rutherford. Cameron and 

 Ramsay had found eight times as much. 



Sir James Dewar also mentioned that 

 some of the calculations of the Hon. J. R. 

 Strutt, regarding the amount of radium in 

 the earth's interior, needed revising, for 

 one well in France produced 30 liters of 

 helium per day, corresponding to 100 tons 

 of radium. 



Some Reactions of Dichloro Urea: F. D. 



Chattaway, D.Sc, F.R.S. 



Urea is so well known and has been so 

 much investigated that any new simple 

 substance obtainable from it possesses quite 

 an unusual amount of interest. Such a 

 new substance is found in dichloro urea, 

 which, leaving out of consideration the 

 derivatives of ammonia itself, is one of 

 the simplest possible compounds contain- 

 ing halogen attached to nitrogen. It is 

 produced when chlorine is passed into a 

 cooled saturated aqueous solution of urea. 

 Action takes place without any consider- 

 able development of heat, and dichloro 

 urea crystallizes out as a white powder 

 consisting bf small transparent plates. 

 Dichloro urea gives all the characteristic 

 reactions of a typical nitrogen chloride; 

 for instance, it liberates iodine from 

 hydriodic acid, chlorine from hydrochloric 

 acid, and reacts with alcohol, forming ethyl 

 hypochlorite, urea being in all cases re- 

 formed. 



A reaction which indicates the use to 

 which dichloro urea may be put in the 

 synthesis of simple carbon and nitrogen 

 rings is that between it and ammonia. 



When ammonia in excess is added to an 

 aqueous solution of dichloro urea, hydrol- 

 ysis, accompanied by liberation of nitro- 

 gen and formation of carbonate, occurs, 

 but in addition diurea is produced, and 

 separates in considerable quantity as a 

 sparingly soluble crystalline powder. This 



is the first direct synthesis of diurea from 

 urea itself, the compound having been pre- 

 viously obtained from ethyl carbonate and 

 hydrazine. 



This adds another to the very few reac- 

 tions known by which nitrogen atoms can 

 be made to link up together, and further 

 affords an exceedingly simple synthesis of 

 hydrazine. 



Diurea, when heated with excess of 

 strong sulphuric acid to a little above 100° 

 C, is easily hydrolyzed, carbon dioxide 

 escapes, and hydrazine sulphate is pro- 

 duced. This crystallizes out perfectly 

 pure in almost theoretical amount on cool- 

 ing and adding a little water. 



The Factors which Influence the Bate of 



Acoholic Fermentation: Arthur Slatoe, 



Ph.D., D.Sc. 



The transformation of glucose into 

 alcohol and carbon dioxide by the action 

 of yeast is probably not a single chemical 

 reaction but a series of reactions. If one 

 reaction of the series proceeds relatively 

 much more slowly than the others, then 

 the velocity of the transformation is de-' 

 tennined by the rate of this slow reaction. 



Evidence is brought forward to show 

 that the initial rate of fermentation by liv- 

 ing yeast is controlled almost completely by 

 one single reaction. 



The rate of fermentation is exactly pro- 

 portional to the amount of yeast present. 

 The rate of fermentation of the four 

 fermentable hexoses (glucose, fructose, 

 galactose and mannose) is almost inde- 

 pendent of the concentration of the sugar. 

 Glucose and fructose are fermented at ap- 

 proximately equal rates. The fermenta- 

 tion of mannose is similar to that of glu- 

 cose, but the rates of the two reactions are 

 not equal. The enzyme which ferments 

 mannose seems to be more sensitive to heat 

 than the one which ferments glucose. The 

 influence of temperature on these reac- 



