RECENT ADVANCES IN SCIENCE 471 



considerable value. The necessary reagent is prepared by dis- 

 solving one gram of hexamethyltri-p-aminotriphenylmethane 

 in 20 c.c. of cold hydrochloric acid made by diluting the strong 

 acid with an equal volume of water. The hydrochloride is 

 then diluted ten times with distilled water and can be preserved 

 indefinitely as a stock solution. It gives an immediate violet 

 coloration if free chlorine is present, when a few centimetres are 

 added to the water under test. In this way it is possible 

 to detect three parts of chlorine in a hundred million parts 

 of water. Traces of hydrogen peroxide are without action, 

 and the reagent has the distinct advantage over the starch- 

 iodide test in that it is not nearly so sensitive to extraneous 

 nitrates. The formate is as effective as the hydrochloride 

 and it is advantageous in carrying out the test to add a 

 little salt and acidify the test samples of water with either 

 acetic or formic acid. 



Technological. — A problem which has in recent years received 

 a considerable amount of attention from the industrial and 

 technological point of view is the underlying cause or causes 

 of the spontaneous combustion of coal under anaerobic con- 

 ditions. A paper has just been published by Drakeley {Trans. 

 Chem. Soc. 191 6, 109, 723) which bears on this subject, more 

 particularly as to the part played by pyrites impurities which 

 are found to a greater or lesser extent in most samples of coal. 

 Drakeley has prepared mixtures of coal and pyrites, coal and 

 ferrous sulphate, and coal and sulphuric acid, and has quanti- 

 tatively measured the oxidation products as well as the rates 

 of absorption of oxygen of these mixtures and compared the 

 results with those for coal and pyrites unmixed. His results go 

 to indicate that the presence of pyrites in coal increases the 

 rate of oxidation and therefore probably considerably increases 

 the possibility of spontaneous combustion in such coal. 



Synthetical. — By far and away the most important develop- 

 ment in the domain of synthetical inorganic chemistry is the 

 production of nitrates or nitrogenous substances from the 

 free nitrogen of the atmosphere. On the Continent this 

 problem has received enormous attention and particularly by 

 our Germanic enemies, who, it is reported, have made them- 

 selves independent of the natural occurring deposits of South 

 America by their synthetically produced products. So impor- 

 tant is this subject that the United States Government have 



