1 873.] A Solution of the Sewage Problem. 65 



the acidifying tanks the semi-dry mud is pumped into the 

 drying-presses, whence it issues in a cake. This semi-solid 

 mud is then further dried by a most ingenious application of 

 heat in revolving iron cylinders. The wet mud is passed 

 in at one end, and dry manure, in the form of an inodorous 

 and inoffensive powder, falls from the other end, at the rate 

 of 5 tons in ten hours, at an expenditure of a few cwts. of 

 coal. 



If space enough be available the mud may be simply 

 pumped from the bottom of the settling tanks into large 

 open-air stanks, where it dries under the influence of the 

 sun and air. Not the slightest offensive odour is apparent 

 during any stage of this drying. 



The dry mud in powder, and forming excellent manure, 

 is removed from the sheds, and packed into bags for 

 transport. . - 



We have thus traced the process from the sewage to the 

 manure and the effluent water. Before enteringupon any state- 

 ments with regard to the value of the results, we will more 

 fully detail the process as it is followed at the experimental 

 works at Crossness. 



Crossness is situated on a projecting part of the southern 

 shore of the Thames, between the Plumstead and Eri.th 

 marshes, and is the southern outfall of the London drainage. 

 The quantity of sewage now daily discharging at Crossness 

 is 50,000,000 gallons. Large as this quantity may appear the 

 enormous engines employed in pumping the sewage are 

 fully equal to the task, for they are capable of lifting 280 

 tons in a minute, or nearly double the average flow. The 

 transformation of such a mighty mass of filth into heaps 

 of shining gold is a feat worthy of the days of the alchemist, 

 or rather of the days of modern chemistry. Of this 

 quantity of sewage the works of the Native Guano Com- 

 pany are capable of dealing in the twenty-four hours with 

 500,000 gallons, drawn from the cross-cut, or culvert through 

 which the sewage runs into the principal reservoir. This 

 quantity amounts to 1 per cent of the whole delivery. 

 Thither the sewage flows into the sump of a pump 

 worked by a 15 horse-power steam-engine, whence it flows 

 into contact with the ABC constituents as we have de- 

 scribed. 



From the mixing trough the sewage, as described, flows 

 to the settling tanks. These tanks are six in number, and 

 are constructed of concrete, each being 50 feet long by 20 feet 

 wide, and 8 feet in depth. When leaving the last settling 

 tank the effluent water is caused to take a considerable fall, 



vol. in. (n.s.) k 



