256 SEWAGE AND ITS PURIFICATION 



other infusoria, proving that a sufficient residue of oxygen had 

 remained to enable some resolving aerobic organisms to assist 

 in breaking dow^n the solids. 



My analysis of the black deposit from the first contact-bed 

 at Hampton, in June, igoo, gave : — 



Water yiS 



Ash ... .."'. 48*37 



Organic matter 44*45 



lOQ'OO 



Total nitrogen ... ... ... ... ... 4*788 



Percentage of N in organic matter ... ... 1079 



Organic nitrogen .. . ... ... ... ... 3*058 



Percentage of organic N in organic matter ... 7-12 



Combined ammonia ... ... ... .. 1*73 



The ash contained : — 



Oxide of iron and mineral salts .. . ... ... 17-00 



Coke ... ... ... ... ... ... 4-18 



Silicious matter ... ... ... ... ... 27-19 



48*37 



The organic matter was therefore closely related to humus, 

 and w^as similar to that found in the septic tank. A micro- 

 scopical examination showed large numbers of anguillulae, with 

 amoebae, a few rotifers and flagellate infusoria, aquatic larva 

 cases and portions of . insects, a few animal hairs, possibly 

 human, and some isolated fragments of muscular fibre, diatoms 

 and desmids (synedra, etc.), vegetable debris, fragments of 

 wood, epidermis, leaf hairs, ducts of ferns, spiral vessels, straw 

 and grass stems. A large quantity of dark brown amorphous 

 matter of humous character. Crimson particles and dyed fibres, 

 blue and orange, fragments of coke and coal, sand, and car- 

 bonate of lime crystals. 



In September, 1900, 1 found that the black matter collected in 



Stoddart's continuous filter at Knowle, Bristol, amouted to 



4*37 parts per 100,000 of effluent, and contained : — 



Mineral matter ... ... ... ... ... 3i"9i 



Organic matter ... ... ... ... ... 68*09 



loo-oo 



Organic nitrogen ... ... ... ... ... 4*69 



Combined ammonia ... ... ... ... 0-57 



Percentage of organic N in organic matter ... 6-88 



