in Melkourne. 185 



was very foetid and betrayed its origin even to the unaided 

 senses.* 



Case VII. In order better to determine the quantity and 

 nature of the matters added to the water in its passage 

 through the filters, cesspits, and other places whence the 

 samples proceeded, it was desirable to make a similar exami- 

 nation of the Yan Yean water. This step was also a 

 necessary precaution to take, lest, in the event of any legal 

 proceedings being undertaken, the absence of such informa- 

 tion might cause a case to fall through, as an advocate in 

 defence might pretend that the matters detected existed in 

 the water supply. It was therefore essential to be provided 

 with the means not only of declaring that the noxious 

 -agents and indications of decomposition hereinafter to be 

 described, did not exist in the Yan Yean water, but also of 

 distinguishing between the organic inhabitants of that water 

 and those found in the samples examined. I also examined 

 the water of the Yarra, taken within the town boundary, 

 but before receiving the sewage. 



I now proceed to enumerate in order the results obtained 

 from each of the principal samples examined, noting the 

 following particulai-s. 



The residues of both kinds estimated quantitatively. 



The products as indicative of decomposition and of 

 the presence of excrementitious matters. 



The character of the microscopic organisms contained. 



In these analyses, I determined the comparative amounts of 

 solid residue, of organic and inorganic matter, for the purpose 

 of contrasting them with each other and with the Yan Yean 

 water, which in every instance formed the bulk of the fluid. ^ 

 For the detection of faecal matters, &c., I relied chiefly on 

 the presence of nitrogenous compounds already in solution, 

 as ammonia and nitric acid, or in the form of albuminoid 

 substances yielding nitrogen by decomposition ; on the evolu- 

 tion of sulphuretted hydrogen and carbonic acid ; and also 

 on the character of the vegetable and animal bodies revealed by 

 a searching microscopic analysis. All the samples were 

 allowed to settle for a sufficient time before examination, so 

 that grit and other heavy inconsequential substances were 

 eliminated. 



* At the date of this paper, the gully also received the sewage of the 

 ■Government Printing Office. 



