148 I.SC. Proceedings of the Ninth [N.S., XVITI, 
Some observations on the trenching of night soil_—By 
JaHaR Lat Das. 
paper octuda the ohetrntaoes: . the peo on the trenching of 
sia stg at Man cgay a first class nicipal town with a population of 
hose 763 (1911) and only a limited arene (30 bighas) preys oe for trench- 
The Hadise 3 laid down in the Circular issued by the Sanitary 
or Bengal in i ongs 
Oe § 
for two years view to prevent the land from becomin 
pint Cale Bred 6 on Ue basis of this Circular, the total extent of land 
for the purpose at least 200 bighas of ue would have been required. 
Consequent on the limitation thus se , the author decided on re- 
trenching every plot, every oe months. rite r examining them as to 
their fitness for retrenchin He found that in a ripe laeinetee 
trenched soil it took nearly fie but never less than four months for 
transformation of the excreta ie a sort of odourless loose black e ie 
i ti iti reas in a virgi 
and whe 
abou one months more oe excreta to acquire this character. 
Thus every plot was rebrenched about half a dozen times instead of 
once, every thre e yea 
Thes observations were fully borne out at other places adjoining 
Caleutta, viz. Nadi Bagan, ar ohie h, Cossipore, Chitpore Municipality 
and also in other parts of Ben 
e concludes that :— 
(1) The nitrifying organisms in the soil multiply enormously 
e application of seascape excreta and the soil gets im 
oved in quality to such an extent that it can be re- 
iahed mit often then the period originally laid down 
{2} No soi was found to disintegrate in less than four to ro five 
(3) The soil did not appear to become sewage 8 ick. : 
(4) E t from an econo “pom point = view, ae idea that be 
rae 
(5) By not reapplying right coil to as plot for about two ye re 
the plot may acquire more or less the aan of virgin 
seid — stg death of the nitrifying bacteria as a result of 
(6) Hard lay ms ‘soil when retrenched at short intervals improves 
ality and acquires a porous character suitable for 
ies ing. 
Sewage disposal with use of gases for generating electri- 
city and of the effluent for agriculture.—By K. BuR- 
JORJL DapyBtRsoy. 
The present method of sewage rte in awed bei is aa a 
and uneconomical. Septic tan k treatment o and disposal of 
nation with a specially constructed purifier, co nse apltaaigto 2 
taining slaked lime which effectively removes the CO 
