CHEMICAL CHANGES 



107 



the original organic N in the form of nitrate, which is available 

 for plant nutrition. As compared to the voluminous '* sludge " 

 of chemical or mechanical treatment, anaerobic liquefaction 

 leaves only the small quantity of humus residue already 

 alluded to. 



The amido-acid s formed in liquefaction break up into fatty 

 or aromatic acids and ammonia. Since many of them are very 

 stable bodies, the decomposition is slow. Following the general 

 rule, being products of bacterial action, they hinder the activity 

 of the bacteria themselves, furnishing an additional argument 

 for the constant removal of the products by a continuous as 

 opposed to an intermittent system. Examples are : 



» 



Name. 



Glycocine ., 

 Leucine 

 Tyrosine .. 



spartic . . 

 Lsparagin ., 

 rlutamic .. 



Constitution. 



Amido-acetic acid 



Amido-isocaproic 



/3 oxyphenyl-amido- 

 propionic 



Amido-succinic 

 Amido-succinamic 



Formula. 



CH2(NH2)COOH 



\^COOH 



/CHoC6H4(OH) 

 \CH(NH2)COOH 



fCHgCOOH) 

 \CH(NH2)COOH 



/CHoCO(NH„) 

 \CH(NH2)C60H 



rCgH^CNH.) 

 \(COOH)2 



Products. 



Ammonia and acetic 



acid. 

 Ammonia and iso- 



caproic acid. 



As below. 



Ammonia and malic 

 acid, then succinic. 



Ammonia and malic 

 acid, then succinic. 



Ammonia and prob- 

 ably succinic acid. 



Tyrosine has been said to be strongly antiseptic, but its 



uantity in faeces is small, and it is largely diluted in the 



wage. It breaks up into indol, skatol, phenol, and acids 



elated to benzoic. Spirillum rugula and the B. coprogenes 



roup develop a strong faecal odour, probably owing to this 



reaction. In the Exeter and Ashtead hydrolysed effluents I 



h: only found leucine unchanged ; acetic, butyric, and caproic 



acids were, however, isolated, and traces of succinic as well as 



. indol and skatol. 



■B The development of these more or less antiseptic substances 



in the intestines probably accounts for the excreta not being 



further liquefied in the body, although large numbers of the 



necessary organisms are present. On emerging, however, and 



y undergoing dilution the bacteria at once become active. 



