78 BULLETIN 1380, U. S. DEPARTMENT OF AGRICULTURE 
molds in some cases may be developed vigorously. The freshly cut 
surfaces of these balls were frequently observed to be yellow, green, 
or black, depending upon the particular mold present. 
Latex coagulated with formalin and kept for some time in a 
closed box during certain yield experiments became thickly coated 
with molds. The large proportion of moisture in the balls as they 
are made up in the forest is responsible for the A T igorous develop- 
ment of these molds. A microscopical examination in the field 
showed that these organisms are the same as those that may be ex- 
pected to occur on all organic substances in tropical countries during 
wet weather. The forms most commonly observed were species of 
Penicillium, Aspergillus, Oidium, Trichoderma, Sterigmatocystis, 
and other indeterminable Hyphomycetes. 
If the crude rubber is manufactured into sheets or crepe in the 
Tropics the spores of these molds may survive the washing and mill- 
ing process even by the most recent methods and cause molds that 
appear after packing for shipment. Considerable trouble is experi- 
enced with mold on crepe or sheet rubber in transit to the manufac- 
turer. Ribbed smoked sheets from the Orient sent in for examina- 
tion from Xew York were badly molded while in transit. 
The methods employed for preventing moldiness on rubber have 
apparently not been attended with complete success. The applica- 
tion of disinfectants both to the latex and to rubber after manufac- 
ture have been tried. 
A commercial preparation known as chinosol has been used as a 
disinfectant when added to the latex in the proportion of 0.1 gram 
per liter of latex to prevent spottedness in dry crepe or by soaking 
the freshly rolled sheets in a dilute solution (0.05 per cent) to pre- 
vent rustiness. This preparation, however, when used as a disin- 
fectant was not found to prevent molds on sheet latex. 
Some recent research on the subject has been made by Stevens. 
The addition of 1.8 grams of sodium silicofluoride to 3,000 cubic cen- 
timeters of latex and 3 grams to 3,000 cubic centimeters of latex was 
used to prevent mold on smoked sheets. Acetic acid in the propor- 
tion of 1 to 1,200 was used for coagulation. Stevens later verified 
his former results, finding that sodium silicofluoride in the propor- 
tion of 1.8 grams to 3,000 cubic centimeters of latex prevents all but 
the slightest traces of mold on sheet rubber during transport. Ed- 
wards experimented with the same chemical and verified Stevens's 
results. Soaking the sheets before smoking produced resistance to 
mold in a high degree. 
The chief factor promoting the growth of mold is the presence of 
moisture. Thorough drying of both sheets and containers will re- 
duce the extent of molds or prevent their growth altogether if the 
drying is thorough enough. At Para crepe, which ordinarily either 
does not mold at all, owing to its more thorough washing, or is 
attacked to a much less extent than sheets, was found to develop 
mold if rolled up when moist or if placed in a box of unseasoned 
boards. 
Thorough drying before packing to insure the evaporation of all 
moisture in the usual indentations on sheet and crepe rubber, the use 
of bone-dry containers, and storage in dry holds while en route are 
good practices. Aspergillus repem will grow on substrata having a 
