PRODUCTION OF SIRUP FROM SWEET POTATOES. 17 
it was pumped to the supply tank of the evaporator. The pressure 
was applied gradually. 
In pressing the racks and press cloths tended to slip out of place, 
owing in part to the lack of guides to make sure that the ram 
ascended vertically, and in part to the fact that the galvanized wire 
racks did not maintain their position as well as wooden ones. It is 
believed that this difficulty could be overcome by the use of wire 
cloth of coarser weave. It was overcome in the experimental work 
by placing a series of wooden frames around the cheese as it was 
being formed. Three frames, with sides from 6 to 8 inches high, 
were superimposed, fitting one on another, by the use of cleats. Dur- 
ing pressing the uppermost, and finally the middle, frame was re- 
moved. Three cheeses of 10 to 13 cakes each were required for each 
50-bushel lot of potatoes. 
After pressing the pomace was shaken out of the cloths, which 
were then ready to be used again. At the close of each day's work 
the cloths were washed and hung out on lines in the open air to drain 
and dry. A batch of 2.500 pounds of potatoes yielded 200 pounds of 
dried pomace and required 19 hours to dry. The wort received from 
pressing, collected in the catch tank, was pumped to an overhead tank, 
which acted as a reservoir, from which it was drawn by gravity to 
the evaporator as needed. 
EVAPORATION TO CRUDE SIRUP. 
The wort contained about 15 per cent of solids. It was pale 
yellow, with a faint, sweet taste. It was evaporated to approximately 
60° Brix (cold). The most convenient method for operating the 
evaporator was to fill it to a mark previously determined by experi- 
ment, turn the steam into the coils, and evaporate until the sirup 
became so thick that a test portion would just begin to fall in blobs 
or " flake " from the paddle or dipper used in testing. This usually 
required from 15 to 20 minutes. The steam was then turned off and 
the sirup was discharged. A new batch of the wort was admitted 
and the process was repeated. It was expected that the evaporator 
could be made to operate continuously. This, however, was imprac- 
ticable, as it was impossible to control the feed and steam supply with 
sufficient exactness. 
The crude hot sirup thus prepared from the potatoes was received 
in a collecting tank under the evaporator and was later pumped into 
the cooling tank. Here it was allowed to cool and stand until ready 
to be converted into finished sirup. 
FILTRATION OF CRUDE SIBTJP. 
The crude sirup is turbid, containing albuminous matter coagu- 
lated by the boiling, particles of sweet potato tissue, extraneous mat- 
ter, and a small proportion of mineral matter of unknown composi- 
tion which separates upon cooling and standing. After the crude 
sirup had cooled and stood for about 40 hours, thus allowing time 
forthesalttoseparate.it was mixed with enough cold water to dilute 
it to 45° Brix or below. A quantity of ignited kieselguhr equivalent 
to 2 per cent of the weight of potatoes taken was first mixed with 
this water in the catch tank below the evaporator. The same volume 
37996°— 23 3 
