178 Scientific Proceedings, Royal Dublin Society. 



A quantity was inserted into a flask, and the latter placed in an incubator 

 heated to 90° F. (32° C). The flask was connected with Liebig's bulbs 

 containing arsenic chloride (to absorb hydrogen sulphide), and finally with a 

 soda lime tube (to absorb carbon dioxide). 



The experiment extended over three months, and the following results 

 were obtained : — 



Total, 1-079 2 1-063 3 



The total sulphur was determined by treating the sludge with fuming 

 nitric acid, evaporating to dryness, and fusing the residue with sodium 

 carbonate, evaporating to dryness with excess of nitric acid, dissolving the 

 residue in water, and precipitating with barium chloride. 



The sulphur as soluble proteid was determined by treating the sludge with 

 dilute hydrochloric acid, filtering and precipitating the solution with barium 

 nitrate. 



The residue from this operation was dried, treated with fuming nitric 

 acid, the solution evaporated to dryness on a water bath, and the sulphur 

 precipitated in the solution with barium chloride, the precipitate collected, 

 washed, dried, and weighed. This gave the sulphur as insoluble proteid. 



Several other determinations of sulphur in its different forms in foul 

 sludges were made, but, owing to the small quantity of sulphur present 

 in them and the presence of large quantities of mineral matters, the 

 determinations were not satisfactory. 



It will be sufficient to enumerate the different varieties of sludge 

 examined. They were : — 



(2). A second sample of the marine mud. 



(3). Two samples of sludge from the Belfast Pumping Station. 



(4). A sample of (probably) domestic sewage. 



(5). A sample of cesspool sludge. 



1 By substraction : Thus total sulphur minus soluble plus insoluble equals soluble 

 proteid. 



2 0'874 by direct determination. ) 



3 O-SfiO I -These figures are probably too small. 



