EXAMINATION OF SEWAGE 



611 



strained through muslin, and dilutions of 1 in 10, 1 in 100, 1 in 1000, 

 and 1 in 10,000 made with sterile tap-water. These are then 

 examined according to the following scheme : 



EFFLUENTS ONLY. 



8. Incubate some of the effluent in beakers at 22 C. and 37 C. for 



some days. A good effluent should yield little or no unpleasant 

 odour (an unpleasant odour indicates the presence of decom- 

 posable organic matter, and such an effluent might give rise to 

 a nuisance). 



9. Place a gold-fish or two in a bowl of the effluent. The fish will 



live in, and be unaffected by, a satisfactory effluent. (This may 

 be done only by a licensee under the Vivisection Act.) 



