TRANSACTIONS OF SECTION M. Mere. 
whole of Egypt, hatching about 120 million of chicks annually. The non-sitting 
instinct of Egyptian poultry is doubtless due to this old practice of artificial 
incubation. A large installation of American hot-air incubators run on modern 
lines at Alexandria has recently attempted to compete commercially with the 
native incubators, but has proved a complete failure. 
The total quantity of eggs imported into the United Kingdom from all 
foreign and colonial countries now exceeds eighteen million great hundreds* 
per annum, valued at more than seven million pounds sterling. About nine 
hundred million eggs per year are consumed in London alone. The above facts 
emphasise the importance of developing the utility poultry industry by 
introducing hatching operations of a much larger magnitude than is possible 
with small modern incubators. 
The possibility of utilising the simple Egyptian system, somewhat elaborated 
upon and refined, for commercial purposes in this country is suggested. 
3. The Utilisation of Sewage in Agriculture. 
By Dr. J. GRossMann, 
Some of the greatest industries of the present time owe their existence to 
the utilisation of by-products which at some time were considered a nuisance ; 
and sewage, which is the largest by-product, may in like manner become a valu- 
able commodity. The total value of the nitrogenous matter, phosphates, and 
potash compounds contained in its liquid part is equal to twenty million pounds 
per annum. The value of its solid matter, termed sewage sludge, is about two 
million pounds per annum, and the author has succeeded in designing a practi- 
cable method by which this amount can be made available. At present, the 
process only deals with the sewage of Oldham, a town of 150,000 inhabitants. 
It is based on the reasoning that the highly unsatisfactory results which up to 
the present have been obtained with sewage sludge in farming are attributable 
to the fact that it contains fatty matter due chiefly to soap and kitchen 
refuse, and that if these fatty matters, which render the soil impervious to 
water and air, and which by enveloping the active chemical ingredients prevent 
them from being dissolved, were removed, a residue of manurial value would 
remain. By the author’s process the dried sludge is mixed with a small per- 
centage of acid and subjected to the action of superheated steam, which carries 
off the fatty matters (which are condensed in water) and leaves an inodorous, 
brown powder, completely sterilised, which contains, on an average, 1.5 per 
cent. of nitrogen, 3 per cent. of phosphate of lime, and °5 per cent. of potash, 
distributed in almost molecular state over from 30 to 40 per cent. of organic 
matter similar to humus, and mixed with a certain amount of carbon in an 
extremely fine state of division. The results obtained from the residue mixed 
with phosphates and potash compounds are beyond what might be expected 
from calculations based on the units of the active principles. The process does 
not add to the cost of sludge disposal, is automatic, and works day and night 
without a break and with only such labour as is required in attending to the 
fires under the drying machines and boilers, and to mechanical movements. 
There is no smell from any part of the apparatus, and the men do not handle 
the sludge from beginning to end, as everything is carried on in closed vessels. 
The solution of the problem of sewage sludge disposal should place the much 
larger problem of the application of liquid sewage to farming within closer reach 
of solution. Up to the present, the tendency in sewage treatment has been to 
reduce the amount of sludge, as in practically every place it has been a source 
of great expense and nuisance. It is now possible, and even advisable, to pro- 
duce more sludge, and by doing so to obtain better effluents with reduced 
purification plants. ‘So far, the great drawback in sewage farming has been that 
the sewage has had to be used whether the land required it or not. With a 
system of removing the solid matter (including the fatty compounds) from 
sewage without extra cost, the efficiency of the sewage purification plant would 
be greatly improved, and arrangements could be made by which the sewage 
could be, at any time, either sent on the land or dealt with in the purification 
1 One great hundred =120 eggs. 
3D2 
