Chemical Changes in the Fermentation of Dung. 
331 
roused to call persons' thoug'hts to the mode of destroying the 
effluvia a quantity of earth about equal to the blood was thrown 
over it. Tlie cure Avas instantaneous, and no further complaint 
was made though the whole of the stuff was left for a fortnight 
where it was first placed. No gas was given off which could 
be detected by smell or test-paper. 
IV. From the same person was purchased at the same time 
about 20 tons of slaughterhouse refuse consisting of the partially 
digested food taken from the insides of animals which were 
killed, and of waste pieces of skin, flesh and hair removed in 
dressing the carcases for sale. This was carted to the same field 
as the former, and, like it, was left uncovered to arouse atten- 
tion, which it did most effectually. Several tons of night soil 
were added to the heap and the whole was covered with earth, 
when no more annoyance arose from it than from an equal quan- 
tity of dry sawdust. As a manure I never saw anything equal it 
for efficiency. 
V. Forty loads of sods from an old pasture were laid to rot 
and frequently watered with ' steepwater ' from a maltkiln. 
The latter is a substance abounding in nitrogen and earthy salts 
from the barley. With these were mixed as much cabbage and 
green refuse as could be accumulated, amounting to about six- 
teen loads. From this ordinary tests could detect the escape of 
neither ammonia nor sulphuretted hydrogen. Four tons of waste 
Avool containing a good deal of oil were then added as a body 
consisting of much nitrogen and sulphur, well known for its 
generating great heat when moistened, and for the foetid odours 
given off during decomposition. The same result being obtained, 
13 tons of mixed horse, cow, and pig dung were added, and 
then, after a short time, about eight tons of nightsoil. The heap 
now consisted of materials which were as likely to evolve am- 
monia and give off offensive odours as anything we can conceive. 
No smell however being perceptible, and no reaction appearing 
with test-paper, a feather moistened with hydrochloric acid was 
employed. This was held over all parts of the heap and at the 
lee side of it and then away from it in the air, but no difference 
could be perceived in the two cases. It was then taken to the 
neighbourhood of an old fashioned manure heap* containing some 
fifteen loads, when the white wreaths gave a lesson which it may 
be hoped will be learnt effectually by those whose wealth is thus 
hourly dissipated. 
I have avoided laboratory experiments as much as possible in 
this essay, because t know the objection which practical men 
* Potatoes manured with this heap yielded little more than half the crop of 
those manured with the other. 
