26 SCIENCE PROGRESS 



the barium salt, which is produced by the continued absorption 

 of air from carbon activated with iron or nickel after the 

 potency of these catalysts appears to diminish, liberates no 

 gas, decomposes acidulated boiling potassium permanganate 

 solution, and gives with solutions of metallic salts precipitates 

 which gradually decompose with the liberation of gas. These 

 observations indicate that the product is either an oxidized 

 or polymerised oxan. 



The analogy between the oxans and carbon dioxide at 

 once suggests a search for the former in nature amongst the 

 habitats of the latter gas. Thus Lidov has extended his 

 investigations to the atmosphere, natural waters and mineral 

 carbonates. Different limestones were decomposed with phos- 

 phoric acid and the resultant gas was passed over calcined 

 magnesium. The latter material, especially if it contains 

 aluminium, potassium or calcium or magnesium silicide as 

 impurities, is an absorbent for the active monocyanogen. 

 The results of these experiments show that the density of the 

 gas from calcite is considerably lower than that of carbon 

 dioxide. That from aragonite or chalk almost exactly corre- 

 sponds to the density of carbon dioxide, whilst that from 

 marble and other dense limestones is greater than that of 

 carbon dioxide. Undoubtedly, then, the natural carbonates 

 contain varying amounts of active a-monocyanogen — the 

 calcites consisting indeed chiefly of calcium a-oxanate. 



Calcite thus contains both calcium oxide and nitrogen, and 

 on this account ought to be very useful as a fertiliser. Lidov 's 

 investigations perhaps require further substantiation before 

 they meet with general acceptance by chemists, but they are 

 undoubtedly of the highest significance, and mark one of the 

 most important advances which have been made in the domain 

 of inorganic chemistry in recent years. They may, perhaps, 

 be invoked to explain the crystallographic differences in the 

 alkaline earth carbonates, and they may even have far-reaching 

 results in the domain of the practical fixation of atmospheric 

 nitrogen. We have no hesitation in laying particular stress 

 on the importance of this work, and the necessity for its further 

 confirmation and investigation. 



Another reaction which is to be credited to the extending 

 use of catalysts in chemical reaction is that due to Haworth 

 and Irvine (5), in the case of the preparation of hypochlorous 



