Marine Muds and Nodules 141 



acids, diluted, and filtered if necessary, barium chloride solution 

 added, allowed to stand, filtered, and the precipitate of barium 

 sulphate weighed. 



In the first few samples the barium sulphate was not weighed, 

 but the quantity of sulphur judged by the amount of barium 

 sulphate precipitated. 



At first bisulphide of carbon was used, but it was departed 

 from, because, although perfectly pure, and leaving no trace 

 of sulphur on evaporation, it was thought that it would be 

 to use a solvent not containing any sulphur. A portion 

 of the blue clay from the Sound of Jura, which when fresh 

 contains much sulphide, was in the dried state tested with 

 both solvents, with the following results: 



Treatment with Bisulphide of Carbon. A quantity of the 

 clay was pounded and dried at about 80. 50-00 grammes were 

 put into a bottle with 236-0 grammes of bisulphide of carbon, 

 and allowed to stand all night. A weighed portion of the 

 carbon bisulphide was then taken out and put into a weighed 

 flask, and the carbon bisulphide distilled off, and the residue 

 weighed. 0-28 per cent, of sulphur was found in this way. 

 The sulphur dissolved completely in a small quantity of 

 Iphide. Next day another portion of carbon bisulphide 

 was taken out and put into a weighed flask, distilled, and the 

 residue weighed. This gave 0-33 per cent, of sulphur. 



bisulphide was tested to see whether it contained 

 any free sulphur; it turned out to be very nearly pure. 

 Treatment nith Chloroform. Another 50-00 grammes of 

 were treated with 183-6 grammes of chloroform. The 

 mixture was heated for an hour on the water-bath at about 

 the temperature of boiling chloroform (61 C.). A portion of 

 hloroform was then taken out, evaporated, and the residue 

 ^'hed. This gave 0-39 per cent, of sulphur. 



as very little nil present in the residue, which was 

 nearly pure sulphur. 



In th< first ten samples the BaSO 4 was not weighed, but 

 lue was oxidised and the presence of sulphur 



proved nation of sulphuric acid. \Vhrn Milphur 



found constantly and in appreciable quantity, I 



