Based on the experiments described in Part I, methods of analysis of sulphur compounds that have been found successful are described in detail, followed by a scheme of analysis for a complete examination of the sulphur compounds in a crude or refined benzole. For the sake of convenience, the methods of analysis are given in the order in which they appear in the complete scheme.

Until recently the sulphur compounds in crude benzoles were generally considered to be chiefly carbon disulphide and thiophene, although the presence of other compounds such as sulphides, disulphides and mercaptans had been reported. With the exception of carbon disulphide, methods of estimation had not been accurately worked out and knowledge concerning the exact quantities of other sulphur compounds was scanty. Examination of a large number of crude benzoles in these laboratories had shown that normal high‐temperature benzoles contain approximately half their sulphur content as carbon disulphide. It has been customary to regard the remainder as thiophene and its derivatives, an assumption that is justified to some extent since other sulphur compounds, such as sulphides, behave in the same way as thiopheno during refining by sulphuric acid. For example, although a large number of makes and types of acid‐washed benzoic have been tested, it has always been found that the remaining sulphur, other than as carbon disulphide, was the same for a particular yield of benzole irrespective of the concentration and quantity of sulphuric acid used to obtain this yield.

An account is given of an investigation of the composition of sludges from petroleum oils used for recovering benzole at coke‐oven and gas works. This investigation was carried out by the National Benzole Association for the Benzole Technical Committee of the Ministry of Fuel and Power and forms part of the programme of work carried out during the war by that committee on the sludging of petroleum oils, with a view to reducing the consequent loss of crude benzoic. A more complete knowledge of the nature of the solid material contained in the sludges, it was hoped, would give some clue as to its source, and the causes of its formation. For full details of the investigation on sludging, the Report of the Benzole Technical Committee should be consulted.* The material, called deposit, obtained from the sludges after removal of oil and water was extracted selectively with organic solvents. A detailed examination of the deposits and their extracts showed that they were extremely complex in character and that no separation into material of substantially simpler character had been effected. Ultimate analyses showed that all the deposits contained carbon, hydrogen, oxygen, nitrogen, sulphur, and usually iron. Oxygen %vas usually high in amount (5·5% to 36·7%), depending apparently on the extent to which the sludges had been subjected to heat in the plant, and suggesting that the deposits are oxidation and condensation products, rather than polymers of unsaturated compounds. No evidence was obtained that the deposits or extracts contained nitrogenous gum or its heat‐degradation products.