26 Kansas Academy of Science. 



of burial, as indicated in the 23d chapter of Deuteronomy and 

 in the early Hindoo writings. Later came the use of vaults 

 and cesspools, removal by carts, dry-pail methods, burning, 

 compressed air, and water carriage, with its final develop- 

 ment into methods of aiding bacterial decomposition in the 

 modern disposal plant. 



In the operation of the biological machine known as the 

 human body a large quantity of waste material is produced. 

 In the elimination of this material millions of bacteria of 

 various kinds pass from the body. McNeal, Latzer and Kerr 

 report an average of 33,000,000 millions excreted from the 

 normal adult in one day. These facts, which are matters of 

 common knowledge with us, were generally unknown to the 

 earlier generations of the human race. That anj^ escape the 

 dangers from the accumulation of this excretal material scat- 

 tered by millions of flies and other insects is almost a marvel. 

 To effectually destroy the pathogenic species of these micro- 

 organisms in order to prevent recontamination of food and 

 water supplies of human habitations is one of the problems 

 confronting the present-day sanitary engineer. 



While many of the complex processes that enter into the 

 decomposition and mineralization of sewage contents are yet 

 imperfectly understood, the work of the chemist and bacte- 

 riologist are yielding definite results in this line, as is indi- 

 cated by the recent construction of many sewage-disposal 

 plants designed more nearly than ever before to meet the 

 requirements of theories developed in the laboratory. By 

 careful study of putrefactive processes, and accurate compari- 

 son of structural features with results in sewage-disposal 

 plants now in operation, the necessary requirements to pro- 

 duce a satisfactory effluent under different conditions as to 

 kind and quantity of sewage are well defined. Good results 

 are now certain with properly constructed plants. 



The functions of the various types of bacteria in the puri- 

 fication of sewage are now being carefully determined in the 

 numerous experiment stations and laboratories for sanitary 

 research throughout the country. The results obtained by 

 experiments on Boston sewage by the sanitary research lab- 

 oratory and sewage experiment station of the Massachusetts 

 Institute of Technology have done much to bring exact knowl- 

 edge of the necessary processes in sewage purification to the 



