44 BULLETIX 150, U. S. DEPARTMENT OF AGEICULTUEE. 



GENERAL FAILURE OF THE CENTRAL RENDERING STATION TO MEET THE DEMANDS OE 



THE PROBLEM. 



Our problem being to devise a scheme whereby the valuable mate- 

 rials produced as waste in the canning of salmon in particular and 

 the dressing of fish in general may be saved, any plan which pro- 

 vides for the conservation of only a portion of this must be rejected 

 as inadequate. Therein lies a vital objection to the central rendering 

 station idea — that at best it can render the waste only from those 

 fish-cleaning establishments which happen to be grouped together in 

 close enough proximity to make the collection of the waste econom- 

 ically possible. In the Columbia River region this plan as now ac- 

 tually applied results in the utilization of 800 tons from a total of 

 4,000 tons. In the Puget Sound region four of these stations con- 

 serve a total of 15,500 tons, out of a total of 38,750 tons. The scheme 

 as suggested for ideal conditions, as well as when actually applied, it 

 is reiterated, falls far short of meeting the demands of the problem. 



THE SMALL BY-PRODUCTS PLANT OPERATED AS AN INTEGRAL 



PART OF THE CANNERY. 



As the only alternative to the central rendering station, the sug- 

 gestion is offered of a by-products plant operated as an intimate part 

 of the cannery. This would be a small-unit plant of low capacity, 

 just sufficient to treat the output in waste of the cannery of which it 

 forms a part. 



EQUIPMENT. 



For equipment the old-fashioned, unimproved retort cooker and 

 hydraulic press are recommended, not because they are regarded as 

 ideal, but because they constitute the only apparatus which the 

 writer has seen in successful operation on a small scale. It has been 

 demonstrated, and is being demonstrated daily, that this form of 

 apparatus will render salmon cuttings, affording a good grade of 

 scrap and a fair yield of oil. The demonstration has not been con- 

 fined to large-scale operations, but has been attempted on a small 

 scale as a strictly by-products plant, with satisfactory preliminary 

 results. 



The equipment, as has been pointed out in a foregoing paragraph, 

 consists essentially of retort cookers, a hydraulic press, and a drier 

 of suitable form, heated by steam or hot air, as the experience and 

 wisdom of the designer indicate. From a " one-line " cannery, or 

 one with a maximum capacity of 900 cases per day of 12 hours, 

 would be obtained a maximum of 18 tons of waste. This figure is 

 based on the estimate of 40 pounds waste per case. The by-products 

 plant possibly should have sufficient cap'acity to render this volume 

 of waste in a run of six hours; that is, a capacity of 6,000 pounds 



