316 Scientific Intelligence. 



3. The relative atomic weights of oxygen and hydrogen. — A 

 new determination of this important ratio has been made by 

 Julius Thomsen. The novel feature of his method consisted in 

 evolving hydrogen, by means of strong potash and metallic 

 aluminium, from a weighed apparatus and determining the 

 amount of the element used from the decrease in weight of the 

 apparatus. The result arrived at from a series of experiments 

 was 



H: = 1: 15-8690 ± 0*0022. 



This result agrees with remarkable closeness with the results 

 of a number of other investigators, as will be seen from the fol- 

 lowing list cited by Thomsen : 



Cooke and Richards 1 : 15*869 



Rayleigh and Scott 1 : 15*862 



Morley _ _.. 1: 15*879 



Noyes. 1 : 15*886 



Dittmar and Henderson 1 : 15*867 



Leduc 1 : 15*881 



The author believes that the ratio is now definitely settled 

 within very close limits, and there is no doubt that most chemists 

 will accept a ratio very close to this, especially in view of the 

 very elaborate work of Morley. — Zeitschr. anorg. Chem., xi, 14. 



h. l. w. 



4. The synthesis of caffeine. — The complete synthesis of this 

 important alkaloid, the active principle of tea and coffee, has 

 now been made possible by the work of Emil Fischer and 

 Lorenz Ach. The important step accomplished by the authors 

 is the conversion of ^/-dimethyl uric acid, by the action of phos- 

 phorus pentachloride, into chlortheophylline. The latter, by 

 reduction to theophylline and subsequent methylation, gives 

 caffeine. The ^/-dimethyl uric acid has been produced, in a 

 roundabout way only, from dimethyl urea as a starting-point, and 

 the authors therefore consider the synthesis of no practical value 

 at present on account of the expense. They believe that their 

 results would have a practical importance if it were possible to 

 methyllate uric acid directly so as to place two methyl groups in 

 the alloxan nucleus. It is their opinion that as soon as the base 

 becomes a cheap material through artificial preparation, it may 

 have use in the manufacture of substitutes for tea and coffee to 

 give them the same physiological action as the natural materials. 

 — JBerichte, xxviii, 3135. h. l. w. 



5. ffiee hydrazine. — CuvU us, who discovered and investigated 

 hydrazine, obtained the hydrate, N 2 H 4 .H 3 0, but did not suc- 

 ceed in isolating the anhydrous substance. Lobry de Bruyn 

 has now obtained the free base by two methods. The first 

 method consists in treating the hydrochloride with sodium 

 methylate, when the following reaction takes place : 



N a H 4 . HCl + NaOCH, = JST 2 H 4 + NaCl + HOCH 3 . 



