54 The Philippine Journal of Science 
a practical method for open-pan boiling of nipa sap. The pre- 
vious nipa-sugar experiments of the Bureau of Science have 
tended more toward testing the suitability of tuba for large-scale 
sugar-mill methods than to the development of the industry in 
asmall way. A large investment of capital in a nipa swamp on 
the basis of laboratory data alone, however, would be unsafe, and 
our recent efforts have been to develop a method that would be 
feasible on a small scale with a small investment. 
The use of open pans, or cauas, instead of vacuum apparatus 
makes the boiling house inexpensive, but the replacement of a 
large-scale carbonatation equipment by home-made apparatus 
is more of a problem. The Indian method of using so little lime 
that it need not be removed does not seem efficacious in Philip- 
pine nipa swamps, so carbonatation or some equivalent process 
must be employed. . 
A small-scale carbonatation outfit yoently set up at Catarman 
is shown in Plate 3, fig. 3. Charcoal is burned in a tight clay 
stove, a small blacksmith’s forge supplying the draft. The fumes 
are conducted through a 10-inch stovepipe filled with stones. 
Limed tuba is allowed to trickle down this tower, the same tuba 
being run through about four times. The carbon dioxide from 
the burning charcoal precipitates the lime as carbonate, and the 
heat is generally sufficient to cause the precipitate to flocculate, 
or “break,” especially if the tuba is run through slowly the last 
time. The hot liquid is filtered through sand placed in kerosene 
cans having pierced bottoms, and the clear filtrate boiled down 
in open pans. 
The yield of crystalline sugar at the Catarman plant has so 
far not been good, apparently because of the low-grade tuba from 
the wild swamp there. The study of tuba variation and of 
small-scale utilization of tuba is being continued. 
Acknowledgments and thanks are due to Ayala & Co.; Mr. 
José Hernandez, of Capiz; and Mr. Wiren, of the Catarman 
Agricultural School, for the codperation which has ‘made possible 
the experiments mentioned in this paper. 
