3. That it may be reasonably anticipated that a substantial profit would result from the general application of the process.
The yields of valuable products, of course, vary within very wide limits, depending upon the composition of the sewage, but, speaking broadly, the amount of ammonia as sulphate ranges between 60 and 130 pounds per ton of sewage containing 5 to 10 per cent of moisture. Oil, from 18 to 40 gallons per ton; fat, from 5 to 10 per ton; gas, from 14,000 to 17,000 cubic feet per ton. The rare products, it is difficult to give any reasonable figures. Then, after these products have been extracted, there is a residue which has a commercial value as a fertilizer base, as it contains products valuable for agricultural purposes. It is an inodorous grayish-black friable substance having the following general composition.
| Siliceous matter | 66.30 |
| Iron oxide and alumina | 7.30 |
| Calcium carbonate | 3.44 |
| Carbon | 20.40 |
| Magnesia | .07 |
| Phosphoric acid | 1.14 |
| Moisture | |
| Sulphur | 1.09 |
| 99.74 |
The commercial value of sulphate of ammonia may be usually taken at 2 cents a pound, in Great Britain. It is difficult to say what the commercial value of these products is to-day, in war time. We obtain from 5 to 10 per cent of fat, and under special conditions, such as they have at Bradford, which is a wool-washing place, the amount of fat runs up to 20 per cent. It is difficult to give any definite figures as to the value of other products, because they vary in different localities, but there is a fair amount of substances which are used in drug making.
That butter, or residue, after these other products are taken out, is absolutely innocuous, and quite a deodorizer because of the amount of carbon it contains.
That material is used by the fertilizing companies and they add to it the requisite amount of ammonia or phosphoric acid, or potash, or what is required for particular kinds of agriculture.
One of the chief products is oil, and the analysis of the crude oil obtained from the process is as follows:
| By volume. | ||
| Specific gravity at 15° C | per cent | 9.931 |
| Light oil boiling under 170° C | do | 5.000 |
| Light oil boiling between 170-230° | do | 19.600 |
| Light oil boiling between 230-270° | do | 18.700 |
| Light oil boiling between 270-350° | do | 29.900 |
| Residue, a soft pitchy substance, valuable for many purposes | do | 26.800 |
| 100.000 | ||
The crude oil is a very dark thick-looking substance, very much like what you would see lubricating any bearing of engines, and very much like the crude oil that is obtained from the oil wells of this country. It can be split up and fractionated into different parts. It has not a very pleasant smell or a very unpleasant smell; it is quite different from the ordinary crude oil you get from the earth, but several different spirits can be obtained, which are useful for driving motor cars, internal combustion engines, and so on.
After that black crude oil has been split up into these various grades, and various other compounds taken out, there remains in the still a pitch which is practically animal pitch, and which is useful for all kinds of things for which bone pitch is used. [Sample produced.]