44 BULLETIN" 150, U. S. DEPARTMENT OF AGRICULTURE. 
GENERAL FAILURE OF THE CENTRAL RENDERING STATION TO MEET THE DEMANDS OF 
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 capacity to render this volume 
of waste in a run of six hours; that is, a capacity of 6,000 pounds 
