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specified per cent. of oil is lost, and a portion of nitrogen is also lost, resulting from the partial decomposition of the mass, the formation and escape of ammonia. It were better, if practicable, to drive off the water at once upon withdrawal from the press, so as to prevent the loss in question."

Goodale's new process.

293. I have spoken of fish guanos from which the most of the fat has been extracted by special processes (Class No. 5, of page 000). One of these is Mr. Goodale's, of which Mr. Maddocks speaks as follows:

"What has hitherto prevented the driving off of the water imme diately by artificial heat has been the presence of so much oil, together with the gelatinous or gluey matter which is developed during the cooking, chiefly from the skins aud bones. These render the process of drying the scrap a very difficult and tedious one, so much so that comparatively little has been put into the market in that desirable form. The recent discovery of an easy and simple process for removing the larger part of the oil, and also at the same time the gelatinous hinderance to drying, gives promise of a speedy change in this respect. While pursuing investigations relative to utilizing the menhaden as a source of concentrated food, before referred to, Mr. S. L. Goodale, formerly secretary of the board of agriculture, discovered that it was chiefly by the agency of the gelatine that the remaining oil was held in the scrap. He found by thoroughly washing new scrap with sufficient hot water, and agitation, that it lost its jellyish consistence and slimy feel, and that the oil globules were liberated from their lock-up in the tissues, so that the greater part could be easily recovered by draining and repressing, and aiso that after such washing it could be pressed much drier than before. "We can now readily understand why it is that oil, together with a putrid, watery liquid, leaks away from new scrap not many days after it is removed from the press. It is simply because dissolved gelatine, being more readily putrescible than other animal substances, quickly decomposes, and changes to a thin, offensive liquid, which partly drains off. This decomposition, or the change of consistence attending it, so 'lets the bars down,' that more or less oil escapes, while subjected to no pressure whatever, except its own weight.

"Thus by a very easy process, the oil product may be largely increased, the scrap left free from the gluey hinderance to drying, and with less water to be dried out.

"It may appear strange that so simple a method should not have been discovered sooner, but such is the fact. Work had been done on both sides of it. Re-pressing had been tried, using extra strong eurbs, with very powerful pressure, but it failed to give satisfactory results. Recooking had been resorted to, which resulted in injury to the oil and in the development of an additional amount of the gelatinous matter. It is now seen that a simple thorough washing in hot water accomplishes the desired end, with neither of these objectionable results.

"Scrap made by this process last August (1877), and dried in the open air, was lately analyzed at the agricultural experiment station of Connecticut, and the statement of the director, Prof. S. W. Johnson, of New Haven, shows the proportion of moisture to be reduced to 11.45 per cent., cr about one-fifth that contained in the scrap fresh from the press; and the proportion of oil to 4.65 per cent., thus proving that the content of oil in the washed scrap as it came from the press (before drying it) had been reduced to less than 24 per cent. [The percentage of nitrogen was 10.24 per cent., the phosphoric acid 7.50 per cent. These figures refer to the material as dried in the open air.]

"According to these figures, the proportion of oil hitherto lost is, by the new process, reduced from an average of, say 15 per cent. of the weight of the scrap as it commonly issues from the press, to about 2 per cent. The balance, say 12 or 13 per cent., is saved. Let it be assumed, however, that only 10 per cent. can be realized in practice, and that the annual out-turn of scrap from the factories of the Maine association be only 40,000,000 pounds. This would give an annual saving of 4,000,000 pounds of oil, or 533,000 gallons, worth, at current prices at market for 1877, forty cents per gallon, $213,200.

"With reference to drying by artificial means, which is obviously important, no doubt is felt that the apparatus now in operation will effect the work as thoroughly as may be desired, and cheaply and quickly also, provided only the oil and gelatine in the scrap be reduced as above described.

"Two companies belonging to the association have succeeded in drying the scrap in considerable quantities, notwithstanding the obstacles referred to. The scrap is passed through a slightly inclined heated iron cylinder thirty feet long and four feet in diameter, and on the pas sage is agitated by paddles attached to a revolving shaft, and comes out at the lower end dried to about 25 per cent. of moisture. The process will be greatly promoted in dispatch and efficiency by the application of the new oil-saving method, and the whole manufacture will then be under full control. The scrap can at once, upon withdrawal from the press, be subjected to the drying process by furnace heat, irrespective of the state of the weather, and thus the loss of ammonia by decomposition be forestalled. If the contained moisture is reduced to a per cent. no lower even than 20 or 25, the scrap can be kept on the spot at convenience, and without offense to the senses, or transported as required."

Adamson's process.

294. The other process for extracting fat from fish is that of Adamson. It depends upon the use of hot petroleum, naphtha, or benzine, to dissolve the oil. Whole fish, menhaden, or others, as well as scrap, are said to be arranged in layers, in an inclined iron cylinder, the naphtha or benzine directed upon and passed through them. In the passage the oil is extracted from the fish, which are left in an excellent form for dry

ing and grinding. The process is said to be easy, simple, and effectual. The main drawback is the necessity for new apparatus and the rejection of a good share of the appliances now used.

Two samples of fish guano prepared in this way and analyzed at the Connecticut experiment station gave, respectively:

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Immense waste of fish at present.-Possibilities of future manufacture.

295. The accounts of these new processes at my disposal are meager. They seem, however, to promise well, and, if successful, must revolutionize the manufacture of fish guano. The great desideratum has been a means of removing the oil as entirely as possible, saving the nitrogenous matters and yielding a fine, dry product. This seems to have been found. I understand that the Adamson process is to be used in the manufacture of a fertilizer from the fish that are taken along the coast, but thrown into the sea again on account of their low value for oil or food. The benefit to our agriculture from such an economizing of fish hitherto wasted would be immense. Concerning the number of fish thus lost Mr. Goode writes: "I estimate that the amount of fish annually thrown away from the hundred and fifty-odd weirs on our coast cannot fall much short of ten millions of pounds annually, and probably far exceeds that."

"Acidulated fish" and "fish and potash salts."

296. The "acidulated fish" (class No. 6 on page 219) is prepared by treating the fish scrap with sulphuric acid to render the phosphoric acid more soluble. Unfortunately the constitution of the tissues of the fish is such as to resist the action of the acid, and the desired result is only partly attained. A sample examined under the writer's direction gave 7.09 per cent. of phosphoric acid, of which only 1.76 per cent. was soluble in water.

It will be remembered that Pettitt's process for the manufacture of fish waste into a fertilizer was based upon treatment of the fish with acid, and did not prove a success.

Various efforts in this same direction are reported in this country and in Europe, but noue, as I can learn, have been found profitable. The imperviousness of the tissues to the action of the acid has thus far been an insurmountable obstacle to success, and will probably remain so.

The "fish and potash salts" (class No. 7, above) is a mixture, as its name represents, of fish, half-dry scrap apparently, in the specimens I have seen, with German potash salts. The idea is a sound one, in that the salts used, doubtless of the lower grades, like Leopoldshall Kainit, and containing large percentages of chloride of sodium (common salt),

would act as a preservative, and further, the potash supplies a lack in the fish and makes of it a "complete" fertilizer.

The amounts of the "acidulated" fish and "fish and potash salts" in the market are so small as to give them very little importance.

Manufacture of "ammoniated superphosphates."

297. The most important use of fish waste is in the manufacture of nitrogenous," ammoniated," superphospates. These fertilizers, which constitute by far the largest class in the market, owe their value mainly to the two ingredients, nitrogen and phosphoric acid. For phosphoric acid various fossil and mineral phosphates, particularly those from South Carolina and the Island of Navassa, are employed. Of late, mines of apatite have been opened in Canada, and promise to be a rich and important source of phosphates for this purpose. The waste boneblack from sugar refineries is also used in very large quantities for the same purpose. Bone meal is likewise employed, but to a limited extent. The phosphoric acid in all of these is in insoluble or very slowly soluble forms. To render it more available, the phosphates are treated with sulphuric acid, and thus superphosphates are produced.

Various materials are used to supply nitrogen (ammonia) to superphosphates. Dried blood and meat-scrap from slaughter-houses are, next to fish, the most important materials in common use for this purpose. Formerly a good deal Peruvian guano was employed. In Europe considerable sulphate of ammonia is used, but manufacturers there are learning that they can get nitrogen cheaper in American fish and slaughter-house products, and thousands of tons of our best nitrogenous materials are annually taken from us and sent across the Atlantic to enrich English, French, and German soils.

According to the report of Mr. Maddocks, already referred to, "ninetenths of the fish scrap turned out at the works of the Maine association are bought by the manufacturers of superphosphate to ammoniate their products, of which 400,000 tons are produced yearly in the United States. They combine it, when dried and pulverized, with South Carolina phosphatic rock, ground bones, with imported guano deficient in ammonia, &c. It is understood that not over one ton of the fish guano is used in connection with three or four tons of the mineral ingredients." The largest manufacturers of superphosphates in this country are the Pacific Guano Company, whose works are at Wood's Holl, Mass., and near Charleston, S. C. This company use fish and the Charleston phosphate for the manufacture of their superphosphate, the "Soluble Pacific Guano." The Quinnipiac Fertilizer Company, of New Haven, Conn., whose works are on Pine Island, near New London, Conn., and the Cumberland Bone Company, of Boothbay, Maine, are, with the Pacific Guano Company, the best representatives of this most useful industry. The detailed descriptions of their factories and methods of manufacture, prepared by Mr. Goode, are at once too extensive to be

conveniently inserted here, and of too much interest to be condensed, and are therefore given in the Appendix O.

50. CHEMICAL COMPOSITION OF MENHADEN AND OF FISH MANURES.

Analysis of whole menhaden and of flesh and bones of whale.

298. The only analysis of whole menhaden I have noticed is given by Prof. G. H. Cook.* The specimens were taken in the Raritan River the latter part of October.

"Five of the fish weighed four and one-fourth pounds-their average weight being three quarters of a pound. The oil was first separated by adding water to the fish and boiling until the flesh was reduced to a pulp. The oil was then skimmed off and purified from water and other substances by ether. It then weighed 2.66 ounces, which is equivalent to 3.914 per cent. of the original weight of the fish. The substance of the fish remaining was then strained out and carefully dried in an air bath, at a temperature of 290° F., when the dry mass was found to weigh 11.8 ounces. On account of the solvent power of the sulphuric acid, which was added to the fish, it was thought proper to separate all the mineral matters from the fluid in which the fish had been boiled, add them to the dried fish, excluding of course the sulphuric acid. These weighed 1.1 ounces, and added to the weight of dried fish given above, 11.8 ounces, made for the whole weight of the dried matter 12.9 ounces, which is equivalent to 18.93 per cent. of the original weight of the fish. There was still left in the fluid some animal matter, which could not be satisfactorily separated, and was left out. The water in the fish was 77.15 per cent. as ascertained by deducting the percentage of oil and dried matter from 100. The nitrogen in the dried fish was ascertained by ultimate analysis to be 7.76 per cent., which is equivalent to 9.28 per cent. of ammonia. The mineral substances contained in the fish were freed from the organic matter by pressing, and then separated from each other by the ordinary process of analysis."

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