4 BULLETIN 1158, U. S. DEPARTMENT OF AGRICULTURE. 
candies, such as caramels, taffy, and kisses, and those which do not 
require a grain. The same holds true in baking. Doubtless the 
sirup would make a good cooking and table sirup in the household. 
It probably will never come into general use as a table sirup because 
of its characteristic taste, although it might find favor with those 
who like that taste. 
Sweet-potato sirup has qualities which make it a valuable blend 
for other sirups. Like glucose, at present the chief material for 
blending, sweet-potato sirup prevents crystallization of cane sirup. 5 
The commercial application of this sirup is limited by its cost of 
manufacture as compared with that of other sirups. If sweet-potato 
sirup could be manufactured at a lower cost than the other sirups, 
uses would readily be found for it. With the present method of 
manufacture and with the present market value of the other sirups, 
however, this is impossible. It may be that in times of emergency, 
when the price of sugar and sirups soars, sweet-potato sirup can be 
manufactured at a profit. It is doubtful whether sweet-potato sirup 
could be used as a substitute for glucose at its present low cost. 
EXPERIMENTAL WORK ON SWEET-POTATO SIRUP. 
PRELIMINARY WORK. 
During the fall and winter of 1920 the Bureau of Chemistry 
experimented with the sirup making from sweet potatoes in the 
laboratory. The ease with which sirup could be prepared was dem- 
onstrated and the nature of the equipment necessary for its pro- 
duction was determined. 6 The process for the production of sirup 
from sweet potatoes thus developed gave indications of possessing 
promising commercial possibilities. Field operations were therefore 
begun in the spring of 1921 and continued during the first part of 
1922, with a view to studying the commercial application of the 
process, special attention being given to the determination of the cost 
of manufacturing, the market value, and the possible uses of the 
sirup. Fitzgerald, Ga., was selected as the most satisfactory place for 
the experimental plant. 
A few hundred gallons of sirup of fair quality was manufactured 
there in 1921. Small lots of the sirup were distributed among the 
larger manufacturers of sirups, confectionary, soft drinks, cookies, 
biscuits, etc., for expression of opinions on its quality, market value, 
and possible uses. It then became evident that a still better sirup 
was needed to meet trade requirements. With this in mind, further 
laboratory work was done. 
At the conclusion of these laboratory tests the experimental work 
at Fitzgerald was resumed during the early months of 1922. The 
plant was remodeled and numerous improvements were made in the 
installation. About 300 gallons of sweet-potato sirup was produced. 
5 Recent laboratory tests have shown that sweet-potato sirup can be used to prevent 
crystallization in cane sirup. In the tests crystallization was much retarded by adding 
20 per cent by weight of sweet-potato sirup (75.86° Brix) to the cane sirup and entirely 
prevented by the use of one-third by weight of sweet-potato sirup, the composition of the 
resulting mixture being three-fourths cane sirup and one-fourth sweet-potato sirup. Two 
samples of cane sirup were used in the tests. One was Georgia cane sirup of 75.02° 
Brix. apparent purity 61.35 , the other was Louisiana cane sirup of 73.8° Brix, apparent 
purity 72.66. The tests were made by mixing the cane sirup with different quantities of 
sweet-potato sirup, inoculating each mixture with a trace of powdered sucrose and letting 
it stand in cold storage for several months. 
6 " Preparation cf sweet-potato sirup," Chemical Age, 29 (1921) : 151. 
