26 



Zacualpa. This sulphurizing the latex is, of course, easily feasible, 

 but beyond its preserving action on the crude rubber there is very 

 little to recommend it to the planter. From the manufacturer's 

 point of view, however, a very strong objection will be raised, and 

 it seems to me this cannot be overlooked. In whatever way we add 

 solid sulphur to the latex, the quantity will vary on different planta- 

 tions and no uniformity can be achieved. This method further 

 lends itself to adulteration, which the rubber buyers always seem 

 to be afraid of. It would in every case be necessary for the 

 manufacturer to analyse his crude rubber for sulphur, and in most 

 instances he would have to desulphurize the rubber before vulcaniz- 

 ing. As the rubber must be masticated before it is mixed with 

 the various ingredients necessary in manufacturing different 

 articles, there is nothing to be gained in the way of preserving the 

 *' nerve " of the rubber. 



I mentioned above the disinfecting and preserving action sul- 

 phur would have on the crude rubber. My series of experiments 

 on sulphurizing latex and preparing rubber from thus treated 

 material consisted of 63 different experiments, each varying 

 from the others in some more or less important respect. I made 

 good samples of rubber, and bad ones, from the sulphurized latex. 

 In most cases there was no development of bacteria in the rubber, 

 even though the samples of rubber were exposed in the culture 

 jars to an atmosphere full of spores of moulds and decaying latex 

 was poured over the rubber. Inoculation of bacteria cultures 

 made of different forms occurring in " tacky " rubber was tried, but 

 failed to develop on samples where a thorough admixture of latex 

 and sulphur has been accomplished. The preserving power of 

 sulphur mixed into the latex seems undoubted. 



I have tried many various methods of smoking the Castilla 

 rubber, and of coagulating by means of smoke. The most suc- 

 cessful one is, I believe, the following. The fumes of burning 

 sulphur were pressed into the latex for varying periods, and it was 

 found that this assisted considerably the coagulation. I then 

 mixed fumes of burning sulphur with the smoke of creosoted wood, 

 pressed this mixture through a cooling apparatus to slightly bring 

 down the temperature, and thoroughly fumigated the latex. This 

 coagulated quickly and gave a grayish rubber, perfectly trans- 

 parent, with a high degree of tensile strength. It has not 

 deteriorated in the six months that have passed since the experi- 

 ment was made. Whether this method will be incorporated in the 

 manufacturing process on La Zacualpa depends on further experi- 

 ments. The present results indicate that there is a possibility in 

 this direction. 



Rubber Experiments. 



Before ending this brief description of conditions on La Zacu- 

 alpa, I wish to mention a few words about the experiments which 

 are being conducted at La Zacualpa Botanical Station and Rubber 

 Laboratory. This institution began its work on December ist, 

 1905. Its purpose is the scientific investigation of the various 

 problems connected with rubber culture. In the short time of its 

 existence the station has not been able to accomplish very much 



