502 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

 8. Imjyroved metlwds of drying Jisli scrap. 



The Hogle patent drying machine, manufactured at the works of 

 H. B. Bigelow, New Haven, Conu., consists of a boiler containing sev- 

 eral iron cylinders, in which the scrap is placed after it has been taken 

 from the press, and where it is quickly dried by steam-heat. One of 

 these machines is said to convert a ton of scrap into dry guano in aa 

 hour's time. The guano i^repared in this way brings a much higher 

 price than the ordinary scrap. An item in the New York Herald of 

 July 22, 1872, stated that the former would command the price of $35 

 per ton, while ordinary scrap is worth $14. Ordinary scrap contains 

 from 5.06 to 10 per cent, of ammonia, while this contains 15. 



Mr. Haddocks remarks : 



" 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 in the scrap be reduced as above described. 



" Two companies belonging to the association have succeeded in dry- 

 ing the scrap in considerable quantities, notwithstanding the obstacles 

 referred to. The scrap is passed through a slightly-inclined heated iron 

 cylinder, 30 feet long and 4 feet in diameter, and on the passage is agi- 

 tated 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 oil by leakage, mentioned 

 above, and of ammonia by decomposition, be forestalled. If the con- 

 tained 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." 



In early days the fish=scrap was not dried, but was allowed to ferment 

 in great heaps, sometimes not even protected from the weather At the 

 old-fashioned oil- works may still be seen these heaps of foul decaying 

 fish, filled with maggots and flies. Salt is sometimes added ; also kainit, 

 or sulphuric acid. These arrest decay for a time, though nothing is so 

 effective as a thorough drying process. 



