40 Report on an Experimental Investigation on 
collect until thej are nearly full. Then, in order to extract the 
lat from the soap used, the liquor is " broken " by the addition 
of oil of vitriol, a quantity varying in amount but just sufficient 
to neutralise the alkali being used. The fat then separates and 
is skimmed off, and the remaining liquor is passed into the drain. 
It usually takes from two to three days to fill each vat, and 
another two or three to settle and "break" the liquor, so that 
each vat is only emptied once a week. This being done, all the 
contents of the vats pass into the common drain. It might 
appear that this was an unimportant part of the sewage ; it is 
therefore necessary to state that, although there are a number of 
houses in the village, there is scarcely a single water-closet, all 
the night-soil being used for manure, and the surface-water 
going into other channels which flow to the watercourses. It 
thus comes to pass that by far the larger quantity of the drainage 
consists merely of the " sud-water" from the mills. 
The drainage is carried some distance by means of earthen- 
ware pipes to near the bottom of a valley, but at a certain point 
iron pipes are substituted, as the farm lies higher than the 
bottom of the valley. In these the drainage is carried across a 
brook which courses down the valley. On reaching the highest 
point of the meadows irrigated by it, the drainage is received 
into two large cisterns, which are connected by valved outlets 
with pipes which open into one common outflow-pipe. From 
this the sewage outflow is directed down a narrow open channel 
cut in the earth along the brow of the hill, one side of which 
slopes downwards to the meadows, the other to the brook. All 
the sewage is carried off by lateral runnels or shallow trenches 
towards the meadows. 
The better to explain the arrangement of the farm, the an- 
nexed rough diagram (p. 41) may be consulted. It will be seen that 
all the sewage is distributed on one set of fields, the others being 
separated by a deep valley, through which runs a rapid stream. 
It will thus be seen that nearly all the sewage is distributed 
to the fields 1, 2, and 3, none to 4 and 5. The greatest accu- 
mulation takes place at the blind end of the final lateral channel, 
and here there is sometimes a considerable excess of overflow in 
wet weather. The other meadows, 4 and 5, are entirely devoid 
of sewage supply, and 5 is completely separated by the deep 
wooded valley and stream. 
As regards the characters of the sewage, both in the cisterns 
and in the channels it exactly corresponds with that of the 
" sud-water " in the tanks at the mill. It has none of the 
ordinary appearance or odour of sewage, but is of whitish 
colour, and a peculiar soapy, oily smell. The deposit contains 
a large quantity of greasy matter and particles of hair, scarcely 
