680 PROCEEDINGS OF SECTION H. 
all decomposing matter as expeditiously as possible to a place 
outside their city, and that when so removed they knew how to 
dispose of it.”— Baldwin Latham. 
The question which appears to have occupied the attention of 
the ancients is more intensified at the present day, owing to 
changes of condition and other obvious causes. Notwithstanding 
the numerous enquiries and scientific investigations, the general 
opinion is that sewage and other organic filth is troublesome, and 
should be got rid of as quickly as possible, and without endangering 
the public health. 
The question of disposal is very often surrounded with diffi- 
culties and complications, and severely taxes the minds of the 
authorities and pockets of the ratepayers. 
Where a seaboard discharge, accompanied with favourable 
circumstances, can be obtained, the problem is easily solved, but 
where such facilities are not available other means of disposal 
have to be obtained. Notwithstanding years of trials, investiga- 
tion, and large expenditure, the authorities on the subject are at 
variance as to the best means of overcoming the difficulty. Every 
system has its enthusiastic advocates, each considering their 
particular system as the only remedy for the evil. 
In former years considerable value was attached to the sewage 
as a manure, but experience has demonstrated the fallacy of such 
value from a commercial standpoint. 
The various systems which have been tried for purifying sewage 
may be classified as under :— 
I. Filtration. 
II. Chemical treatment. 
III. Irrigation. 
I. The removal of impurities from crude sewage by means of 
artificial filters has not been attended with such success as to lead 
to its general adoption. The glutinous character of the sludge 
entirely clogs the interstices of the filtering material and renders 
it inoperative, and a nuisance is set up by the accumulation and 
decomposition of the foul matter in the filter. The disposal of 
the offensive solid is surrounded with difficulty, and the cost of 
constantly cleansing and renewing the filtering material has led 
to the system being regarded as impracticable and expensive. 
Il. Purification by Chemical Treatment has been practically 
tried in various ways, as well as chemically investigated. 
Numerous patents have been taken out, but few have stood when 
put to a practical test, and in many instances this result has not 
been arrived at except by a large monetary expenditure. 
The various chemicals used for precipitating and purifying 
sewage are:—Lime; lime, with addition of magnesium chloride 
and tar, known as Hille’s process ; milk of lime, with sulphate of 
alumina, Anderson’s process; lime, with iron sulphate; also a 
