NOTES ON SCHOOL CONSTRUCTION, ETC. 679 



backwards the running water comes in better contact. To prevent 

 the boys crowding there should be at intervals a partition of one 

 inch piping let into the wall, bent over, and then let into the ground. 

 If this piping were connected with the water supply, and each 

 vertical portion had a form of sprinkler attached a very effective 

 flushing would ensue. For the girls every w.c. should be provided 

 with a door 4 ft. high and 1 ft. from the ground, and should be 

 provided with an inside bolt near the top, so that a teacher can 

 easily reach the bolt from above in case the doors have been locked 

 by children creeping underneath. It must also be remembered 

 that infants require lower and smaller pans and lower lavatory 

 basins. 



In conclusion I would like to point out the importance of 

 having sanitary paper supplied to all schools. Some time ago 

 when I made suggestions in connection wath the out- offices, I was 

 asked did I expect that the schools should be supplied with such 

 elaborate lavatories as are found at the Central Railway Station 

 and other places. I am sure you will agree with me. that too much 

 cannot be done for the health and welfare of our school children. 



4.— A RAPID METHOD OF DETERMINING THE PROBABILITY OF 

 DECOMPOSITION OCCURRING IN A SEWAGE EFFLUENT. 



By EDWARD S. STOKES, M.B., Ch.M., D.P.H., Medical Officer, Metropolitan Board of Water 

 Supply and Sewerage, Sydney, N.S.W. 



At the present day the usual method of determining the putres- 

 cibility of sewage effluents is the application of the Incubation Test. 

 This test, however, as applied varies so much in details that it 

 becomes a matter of difficulty to compare the results obtained by 

 one worker with those of another. The incubator test appears to 

 have been first used in 1895 by Scudder, who determined the 

 oxygen absorbed from cold acid permanganate in three minutes 

 before and after an incubation period of five to six days at 75°F. 

 Later, Scudder included the determination of dissolved oxygen and 

 nitrates before and after incubation. 



A simpler foi'm of incubator test than the above consists in 

 merely noting the appearance and smell of the liquid after incuba- 

 tion. If the sediment has become dark-coloured from the formation 

 of sulphide of iron, the smell is invariably putrid, whereas, if it 



