18 
IMPERIAL COLLEGE OF 
nitrogen of the manure. They are consequently fully 
justified in subjecting human excreta to thorough decom¬ 
position before using them. 
Night-soil that has been effectively disinfected, behaves 
with regard to its principal nitrogenous ingredient, just 
like undecomposed excreta ; the addition of the disinfectant, 
having the effect of destroying all micro-organisms or at 
least of preventing them from growing and increasing, thus 
entirely suspends the conversion of the urea into ammonium 
carbonate and in other respects also deteriorates the dung. 
From the agricultural standpoint the following objections 
may be raised on the whole against disinfected excreta : 
1. ) They do not undergo decomposition and their 
application may cause, on account of their large 
content of urea, injuries to the crops and loss of 
nitrogen, as above explained. 
2. ) They contain less of fertilizing ingredients, as the 
addition of the disinfectant involves a more or less 
considerable dilution ; hence their transportation is 
connected with greater expense. 
3. ) The disinfectant may be poisonous to plants, and 
the excreta may consequently be either entirely 
unfit for manuring purposes or, at least, be applica¬ 
ble only for special crops and under special con¬ 
ditions, or they may require a special treatment to 
render the disinfectant harmless. 
With regard to the third point, which alone has to be 
decided by direct observation, we carried out some experi¬ 
ments, of which we here briefly state the results : 
Carbolic acid 1} when mixed with water in which seeds 
were steeped for germination, retarded the latter in the case 
1) A detailed description of researches on this disinfectant was pub¬ 
lished in “ Landwirth schaftliche Versuchsstationen,” vol. 30,1883, p. 52. 
