Further on in this report I will give you some figures as to the cost of plant and cost per ton of drying pressed cake.
Having dried the material, it is in a condition to be treated by destructive distillation, whereby ammonia, oil, gas, fat, phenols, and other materials suitable for drugs and dye making may be extracted.
I show you a sample of the material as dried. It appears in that form [specimen exhibited], and it contains 50 to 55 and 60 per cent of water. After it is dried it becomes absolutely, as you see it there. That specimen is practically free from water; it contains only about 2 per cent of water. That material is valuable as a fertilizer, and it is sold in the form of a butter. [Butter specimen exhibited.]
The value of the material, as any chemist knows, is in its fertilizing contents for particular purposes. For certain purposes, the merchants who deal in the product add the necessary quantities of phosphoric acid that the material is deficient in, to bring it up to Government standard. That material is worth to-day on the English markets from $12 to $15 a ton.
Mr. Gardner. What is the relative proportion of potash to phosphoric acid in that sample?
Mr. Paterson. It varies very much, indeed. In small towns where it does not pay to extract—where there is not sufficient tonnage to pay for extracting the oil and the fat from these other products—they are either put into this form, or, if the towns are sufficiently near a large center, it is shipped on the railway to central works where it is treated for these products. But in isolated cases they simply dry the material by a special process, and they have local sale for it, and it is cheap to operate, so that where a man is usually employed in these plants the man can do the whole thing, and you can practically make a small number of people the limit of cost. Taking about 1,000 as being about the limit, or 500 persons, they can put it into this form and use it for manure purposes.
Oils are interesting to the British people, because we have no oil in England outside of the oils which are obtained in very small quantities from the Scottish shale deposits, so that when you are dealing with several million tons of material which will produce a very large quantity of oil per ton it becomes a matter of extreme interest to the Admiralty.
Sir Boverton Redwood, Bart., D. Sc., F. I. C., and Alfred Gordon Salamon, A. R. S. M., F. I. C., the former of whom is one of the consulting chemists of the British Government, state in a report on this process, made two years ago:
1. That the process is capable of furnishing valuable commercial products for which there is a practically unlimited market. In this connection, we may state that the sample of crude oil distillate which was subjected to test remained fluid until cooled to 20° F., had a specific gravity of 0.971 at 60° F., and a flash point of 256° F. A sample of the redistilled oil previously tested by us contained only 0.24 per cent of sulphur, and had a calorific value of 10,230 calories per gram, or 18,415 British thermal units. It is evident that a product similar to the crude oil examined would be a fuel oil complying with the contract requirements of the Admiralty.
2. That very large supplies of the raw material, viz, sewage-sludge press cake, would be available in this country as soon as it became recognized that such press cake could be disposed of.