Sewage Tanks 113 



large volumes of sewage can be exposed to bacterial 

 activities in specially constructed tanks and filter beds, 

 and the organic matter destroyed in a comparatively 

 short time. This discovery, the outcome of widely scat- 

 tered observations, has finally led to the evolution of 

 the modern plants for the bacteriological purification 

 of sewage. 



In September, 1881, a patent for "The Automatic 

 and Odorless Scavenger" was granted to Mouras in 

 France. The American patent granted to Mouras is 

 dated November 28, 1882. The patents were preceded 

 by twenty years of practical experience, which left no 

 doubt as to the remarkable efficiency of the process in 

 destroying organic matter. The construction of the 

 "Scavenger" was very simple. It consisted of an air- 

 tight, hermetically sealed tank, supplied with a feed- 

 pipe to receive evacuations, kitchen wastes, and the 

 like, and an outlet in the upper part of the tank for 

 the discharge of the sewage. Both of the pipes dipped 

 under the surface of the liquid in the tank, which was 

 completely filled with water before being placed in ser- 

 vice. When anything was discharged into the feed-pipe, 

 an equal volume of liquid was expelled from the tank. 

 The liquid expelled contained disintergrated and largely 

 decomposed material. From the inventor's description 

 of the process, it is evident that the organic matter 

 introduced into the tank was destroyed by anaerobic 

 bacteria. So rapid was the process of decomposition 

 that the excreta was dissolved in eighteen days, while 

 resistant substances, like paper, disappeared in a com- 

 paratively short time, with the formation of products 



