RECENT ADVANCES IN SCIENCE 109 



and does not exert a definite " coarse " chemical action on the 

 polysulphide. 



Again, by suitable arrangement of these two variants, tem- 

 perature and concentration, it is possible to obtain colours 

 comprising the whole range of the visible spectrum. This 

 characteristic blue colour is probably the same as is obtained 

 in fusions of sulphur and salts, such as potassium chloride, 

 and solutions of sulphur in ammonia or sulphur trioxide. 



Undoubtedly the sulphur molecule is a very reactive one, 

 and since its various reactive states are evidenced by light 

 absorption in visible and accessible regions, a study of the 

 absorption characteristics of organic and inorganic sulphur 

 compounds ought to prove well worthy of intensive investi- 

 gation. 



Weimarn's observations are confirmatory of some observa- 

 tions already published. By their recently developed method 

 of preparation of pure alkaline polysulphides from alkaline 

 hydrogen sulphides, Rule and Thomas have shown that in the 

 pure solid state these compounds possess a clear gradation of 

 colour, whilst in solution almost any colour can be produced by 

 suitable variations of solvent, concentration, and temperature. 

 Technical. — Sulphuric acid can perhaps be said to be our 

 most important chemical, and consequently many attempts 

 have been made to obtain it by cheaper methods than by the 

 two standard methods involving the oxidation of sulphur 

 dioxide to sulphur trioxide. Bresciani in a recent publication 

 {Ann. chem. applicata, 4, 343, 191 5) gives results of an attempt 

 to prepare this acid by the action of ozone and steam on 

 hydrogen sulphide at 120 . The hydrogen sulphide and the 

 ozonised oxygen were present in the relative proportions of 

 1 to 11, but the addition of the steam reduced the percentage of 

 the sulphide in the gaseous mixture to 0*02 per cent. After con- 

 densing the gases and separating off unchanged hydrogen sul- 

 phide with cadmium chloride, and the excess of cadmium 

 chloride with potassium hydronide, it was found, however, that 

 only 5 per cent, of the sulphide had been transformed into sul- 

 phuric acid. 



Constitution. — An interesting paper on alumina and alumi- 

 nates has been published by Martin {Mon. sci. 5, 225, 191 5), 

 which marks some progress in the chemistry of this amphoteric 

 element. Martin shows that there is a distinct difference, 



