Chemistry and Physics. 483 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The molecular iceight of sulphur. — Previous investigations 

 have shown that the sulphur molecule probably corresponds to 

 the formula S 8 , or to S 6 , at a temperature slightly above its boiling 

 point, and that as the temperature rises the molecular weight 

 becomes smaller, until between 860 and 1700° it is constant and 

 corresponds to a normal molecule, S 2 . Previous work upon the 

 molecular weight of sulphur in solution, as determined by the 

 boiling-point and the freezing-point methods, has in most cases 

 pointed to the formula S 8 . Orndoeff and Teeeasse have now 

 described an elaborate series of experiments in which the boiling- 

 point method has been used with various solvents, and they con- 

 clude from their results that at temperatures below its melting- 

 point the molecule of sulphur is S 9 , while with solvents whose 

 boiling-points are above the melting-point of sulphur, the mole- 

 cular formula is S 8 . The interesting fact was observed that when 

 dissolved in sulphur chloride (S 2 C1 2 ) the molecule of sulphur 

 corresponds to the normal formula, S 2 . The authors have also 

 made the observation that in carbon disulphide, from which only 

 orthorhombic sulphur crystallizes out, and in benzene and toluene, 

 from which the monoclinic form alone separates, the same mole- 

 cule, S 9 exists. — Am. Chem. Jbur. } xviii, 173. h. l. w. 



2. 1 he absorption of the Rontgen rays by chemical compounds. — 



V 



Novak and Sulc have examined nearly 300 substances in this 

 respect. Their method of investigation consisted in attaching 

 rings of glass to a sheet of paper and placing uniform layers of 

 the finely pulverized materials in the different rings so that the 

 thickness of the layer was o*4 cm in each case. The paper with the 

 rings was then placed over a photographic plate which was envel- 

 oped in black paper, and exposed to the Rontgen rays for a period 

 of 20 to 25 minutes. By comparing the photographic effect of 

 the rays where the substances were interposed, the relative 

 absorptions were' determined. The authors found that a great 

 number of organic compounds containing only carbon, hydrogen, 

 oxygen and nitrogen, are equally penetrable, and hence they con- 

 clude that the absorption has no relation to molecular weight or 

 the arrangement of the atoms. Organic halogen derivatives were 

 found to possess much greater absorption, which increased with 

 the number of halogen atoms present. This effect increased with 

 the atomic weights of the halogens, two atoms of bromine having 

 a greater effect than six chlorine atoms, while iodine derivatives 

 were entirely impenetrable under the conditions used in the 

 experiments. This indication of the influence of elements of 

 varying atomic weight led the authors to examine a series of ele- 

 mentary substances, all of rather low atomic weights. The 

 absorptive power was as follows : 



