39-1 
Seioage- Farming. 
this system could be fulfilled, a discovery of immense importance 
would be made to agriculture ; but there is as little doubt that 
at present we can sc arcely be said to be on the way to such a 
desirable achievement of science by any of the various schemes 
to which I allude. The ABC system, as it is called, is the 
most prominent of these. It professes, by a mixture of alum, 
blood, clay, and other ingredients, to precipitate the solid matters 
in suspension and solution in sewage ; by the addition of sulphuric 
acid to the sediment to fix the ammonia contained therein ; and 
by such means to manufacture a valuable manure. The analyses 
by Dr. Voelcker, however, which have been published in this 
Journal,* and the researches of the Rivers Pollution Commissioners, 
sufficiently prove that the manure produced by this process, is 
practically worthless. A more modest form of the precipita- 
tion system is practised at some places, Northampton among 
others. The solid matters are here precipitated into tanks by 
similar chemical agents ; the water is discharged apparently 
clear ; and the residue is mixed with the sweepings and other 
scavenger's refuse of the town, which have previously been 
passed through a riddle, and the larger matters calcined. This 
manure is sold at os. per ton ; yet, having myself used con- 
siderable quantities of it, for which I paid this moderate price, 
and having carefully compared its effects with those of other 
ammoniacal and phosphatic manures, my own appreciation of 
its worth may be estimated by my declaration that I would not 
accept a further quantity of it if I had to cart it three or four 
miles at my leisure. The pollution of the river Nene has 
moreover become so serious that injunctions have been obtained 
by dwellers on the stream, and this case, with others similar 
to it, fully bears out the Commissioners' words — " We have 
never taken a sample of efHuent sewage which had been 
subjected upon a working scale to any of these cleansing pro- 
cesses, which was not still so highly charged with putrescible 
animal matters as to be utterly unfit for admission into running 
water." Good service has been done to the public health, and 
also to the agricultural interest by the examination of this 
and kindred schemes, and the ABC system (at least so far as 
its value to the farmer is concerned) may be said to have 
received its death-blow. Practical sewage farmers are well 
aware that the least valuable of the matters which reach them 
are the solid, the ammonia having passed into the water, which 
has a remarkable natural affinity for it. 
I must not omit some mention of a process lately patented by 
Mr. D. Forbes, F.R.S., and Dr. Price, in which phosphate of 
* 2nd Series, Vol. VI. Part II., p. 415. 
t Second Keport, 1870. 
