420 Composition and Practical Value of Native Guano. 
than raw sewage. Wherever practicable, therefore, clarified and 
disinfected sewage should not be wasted, but employed for 
irrigating our fields. 
The matters held in suspension in sewage, as stated already, 
have comparatively but little value. Still, taking into con- 
sideration the enormous quantities of sewage, at present for the 
greater part wasted in this country, and the fact that purified 
sewage is better adapted for irrigation than it is in a raw state, 
it might be worth while to precipitate the suspended matter if 
it could be obtained at a moderate expense in a sufficiently 
concentrated and dry form. 
Works for the extraction of manure, and the defoecation of 
sewage, have been established at Leamington and Hastings by 
the proprietors of the patent ABC process. The native guano 
prepared by the ABC sewage process of the Native Guano 
Company, Limited, professes to be a valuable fertiliser which, 
having commanded a ready sale at 3/. 10s., is now offered at 5/. 
per ton, delivered at any railway station in England or Wales. 
In the preparation of this manure, the sewage deposit, in a 
semi-solid state, is pumped into centrifugal drying machines, in 
which it loses about 50 per cent, of water. The comparatively 
dry mud is then taken out of the revolving cages, spread out in 
thin layers and exposed to the air and sun until it becomes 
sufficiently dry and powdery to be bagged and sent out. 
In the printed circular issued by the Native Guano Company, 
on which the price of the manure is quoted at bl. per ton, the 
subjoined statement occurs : — 
" The following analysis of the manure as sold to the farmers 
gives an idea of its composition- 
Water 14'1 
* Organic matter 22-4 
Phosphate of lime 9"6 
Earthy and alkaline salts 11"2 
Silicates 42-7 
100-00 
*Nitrogen = ammonia 4 • 2 " 
In the second report of the Commissioners appointed in 1868 
to inquire into the best means of preventing the pollution of 
rivers, Dr. Frankland gives the following analysis of the preci- 
pitated mud which, under the guidance of the Messrs. Sillar, 
the patentees of the ABC process, was extracted by the Com- 
missioners from one of the subsidence tanks at Leamington on 
the 1 0th of last May, 
This mud, acidified with dilute sulphuric acid to prevent 
