Utilisation of Toicn Sewape. 
77 
anv certaintv, the distinctions supposed. It will l)o understood, 
therefore, that the basis of the above estimates as to the amount 
and value of the milk yielded from each acre is the amount 
of grass obtained from each acre. 
"The results show that the quantity of milk obtainable from 
the produce of each acre of land depended very much upon the 
quantity of sewage applied. Deducting the value of the milk 
produced from the grass of the unsewaged from that from each 
of the sewaged acres, reckoning it at 8c?. per gallon, it appears 
that where about 1400 tons of sewage were applied during the 
seven months, the produce calculated for each 1000 tons of 
sewage actually applied gave an increased amount of milk to the 
value of 51. 1 9s. 10c?. ; where twice that amount of sewage was 
applied, 51. 18s. Sd. ; and where three times the quantity, 
5/. Os. Ud. 
" It will be observed that the cows on unsewaged grass both 
consumed more and yielded more milk per head per day than 
those on sewaged grass ; but the proportion of milk to a given 
amount of fresh grass consumed is almost identical in the two 
cases. As will be seen further on, however, the unsewaged grass 
contained a considerably higher proportion of dry or solid sub- 
stance than the sewaged. The question arises whether, or in 
what degree, the comparatively limited consumption of sewaged 
grass (with the coincident lower actual yield of milk per head), 
was due to its very great succulence, the proportion of water to 
dry substance in the food practically setting the limit to the con- 
sumption. However this may be, the result was that a given 
amount of dry substance of the sewaged grass yielded very 
much more milk than the same amount of that of the un- 
sewaged. 
" IV. Composition of the Seivage- Water. 
" Samples of the sewage-water, as it was delivered into each 
field, were taken as follows : — Whilst the sewage was distri- 
buting, samples of about a quart were taken at intervals of two 
or three hours, from the full gauge '.tank in the field, which 
held 3| tons of the fluid. These samples were collected in a 
carboy for a period of a week, when, after well agitating, a 
sample of the mixture was sent to Professor Way for analysis. 
During the first two or three months of the experiments such 
samples were taken nearly every week, but afterwards only every 
fourth week. There were thus, for the months of April to 
October inclusive, 12 samples of sewage-water from each field 
submitted to analysis." 
[The results of the 12 analyses of sewage- water from the five- 
