520 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Crystallized Chlorophyl. — An important contribution to 

 our knowledge of the green substance of plants has been made by 

 Willstatter and Benz. Following up the observation of 

 Borodin, made in 1881, that when microscopic sections of green 

 leaves of various plants are moistened with alcohol and allowed 

 to dry slowly upon the object-glass, peculiar green crystals are 

 often obtained, they have succeeded in preparing such crystals 

 on a large scale, apparently in a very pure condition, and have 

 recry stabilized and analyzed them. This is the first time that an 

 actual chlorophyl has been studied analytically, for it has been 

 shown that the preparations of Hoppe-Seyler and Gautier were 

 products of the decomposition of chlorophyl by acids. The 

 analyses showed some variations in the different preparations in 

 their contents of carbon and nitrogen, but the surprising fact was 

 shown that chlorophyl is a magnesium compound and leaves a 

 residue of pure magnesium oxide upon being burnt. Two 

 analyses are as follows : 



Crude Recrystallized 



product preparation 



Carbon 66-41 65-83 



Hydrogen '._ 6'27 6*15 



Nitrogen 7 : 46 8*24 



Magnesium 3-40 3*40 



Oxygen -46-46 16-20 



The composition corresponds best to the formula C 3b H 42 7 N 4 Mg. 

 The crystals are usually 0-1 to - 2 mm in diameter, sharply defined, 

 and usually of hexagonal or triangular outline. They are bluish- 

 green in color ; in transmitted light only very thin scales show a 

 green color, and generally they are opaque. They are character- 

 ized by a strong metallic luster, especially in sunlight, where they 

 show wonderful reflections. — Liebig's Ann., ccclviii, 267. 



H. L. W. 



2. Mercury Peroxide. — When metallic mercury is covered 

 with a ten per cent solution of hydrogen peroxide, and the liquid 

 is neutralized by the addition of a few drops of dilute sodium 

 acetate solution, an intermittent evolution of oxygen takes place, 

 in the form of regular pulsations. Previous to each period of 

 oxygen evolution there is formed upon the surface of the mercury 

 a yellow or brown film, which is decomposed again as long as the 

 catalysis continues. Von Antropoff has attempted without 

 success to isolate the substance of which this film is composed. 

 He was able to increase its stability by lowering the temperature 

 and using 30 per cent hydrogen peroxide, but he was unable to 



