620 



THE INDIA RUBBER WORLD 



[September 1, 1913. 



We also find that during the vulcanization there is a graduaj 

 decrease in the extract, up to about two and a half hours' vul- 

 canization, after whicli it remains nearly stationary. 



When we have taken a rubber with a certain extract, and made 

 a careful mixture, we find there is no increase after mixing and 

 that during vulcanization we have a decrease, so that the fina! 

 product has less than the original rubber. 



Again when we have put the same ingredients into a com- 

 pound in the ordinary way, we have had a considerable increase 

 after mixing, and the usual decrease during vulcanization. In 

 some cases this decrease may counterbalance the increase, so that 

 the final product will show the same amount as the rubber, while 

 in other cases the increase has been too much to be offset by the 

 decrease, leaving the final product with a liiglier extract than the 

 rubber. 



This decrease we think is due to some of the organic extract 

 being volatile at the heat of vulcanization, so that if there is no 

 mcrease due to improper mixing, we should find the final product 

 to contain a lower percentage of extract than the rubber used. 



forth. In Brazil, instead of pruning these shoots they are al- 

 lowed to grow, probably because in the forest conditions they 

 do not grow close together, but at wider intervals. 



Upon a systematic plantation, these shoots should be entirely 

 cut every year, thus obliging the secondary branches to give 



TWO NEW KINDS OF RUBBER FOR MEXICO. 



IN a late number of the Bulletin of the Mexican Director Gen- 

 '■ eral of Agriculture, reference is made to a recent study by 

 Professor Ule of two varieties of rubber : 



1. "Matiihot Dichotoma" — Manitoba— of the valley of Piauhy. 



2. "Manihot Piauhyensis" — Piauhy and Pernambuco, Brazil. 



Commenting on this study. Professor David Thomatis ex- 

 presses the opinion that these varieties are particularly suited 

 to the tropica! districts of Mexico. Their native habitat, in the 

 Piauhy Sierra, is in rocky and stony soil, in argillaceous, sandy 

 and granitic sections, precisely similar to those of the Isthmus 

 of Tchuantepec. The Piauhy Sierra is exposed to much wind. 

 and the varieties mentioned are stated to be low in height. 



GROWTH. 



There is but little difference between the two varieties, the 

 "Dichotoma," however, being the taller, reaching 40 feet, while 

 the "Piauhy" never exceeds half of that height. It is thus bet- 

 ter able to stand the wind, preferring sandy soils and resisting 

 extreme dryness. 



On the other hand, the "Dichotoma" prefers argillaceous and 

 calcareous soils. With these new varieties, it is remarked, it 

 will be possible to utihze locations with stiff argillaceous earth 

 and w-ith loose, dry and sandy soil. The saying that nature 

 abhors a vacuum may be paraphrased as implying that she 

 likewise abhors useless soil. It is for man to study how to 

 utilize waste tracts, and in Professor Thomatis' opinion, the 

 varieties of rubber named, which are new to Mexico, will 

 achieve that object. 



Both of them shed their leaves during the dry season, when 

 there is more wind, which, hovi-ever, does not affect them much. 

 They grow rapidly, attaining within the first four months about 

 seven feet, with a trunk circumference of 6 inches, commencing 

 to produce good latex in the third year. 



CULTIVATION. 



The simplest and most economical arrangement is to plant 

 the trees about 8 feet apart, there being about 600 to the acre. 

 This figure is about four times that usual for Ccara. Para and 

 Castilloa. 



In the first year, the plant assumes the shape of a single 

 trunk, which forms in the second year two branches, each of 

 which develops two secondary branches in the third year. 



PRUXINX,. 

 At this stage, the four branches should be pruned, being left 

 12 inches in length. Pruning should take place shortly before 

 the rainy season, during which many shoots or buds are put 



Proposed System of Pruxixg. 



birth to a new array of shoots. Through this annual pruning 

 the ground gets more light and sun. The annexed figure illus- 

 trates the above remarks as to pruning. 



T.XPPIXG. 



All other varieties of rubber trees are tapped during the dry 

 season. The latex is being formed all the year but becomes 

 finally concentrated when the leaves are falling. 



Dichotoma and Piauhyensis, on the other hand, require some 

 moisture to develop their latex, and are therefore generally 

 tapped during the rainy season. This fact is attributed to their 

 being cultivated in a dry and well-ventilated soil. In the Upper 

 Congo varieties resembling Diclwtoiita are tapped in both the 

 dry and wet seasons. Dr. Thomatis recommends tapping dur- 

 ing the dry season, accustoming the tree to develop and pro- 

 duce its latex at that period, when it w-ould be of better quality 

 and less resinous than at other times. He repeats that with 

 these new varieties tapping can be commenced the third year, 

 while six years is the age to be allowed for Castilloa, and about 

 ten for other trees. Each tree in these new categories can 

 produce annually more than 2 pounds of latex, which will .give 

 50 per cent, of excellent block rubber. This, it is added, is twice 

 the yield of any other rubber tree. 



ADV-^NTAGES OF NEW VARIETIES. 



To use the author's own words : "All these advantages rep- 

 resent large amounts saved in labor and materials for extensive 

 plantations, and I would venture to say that in this way, if all 

 the above points are taken into consideration. 50 per cent, of 

 the expenses of tapping would be saved. It will easily be seen, 

 that by cultivating these new varieties, the yield per tree only 

 requires three years to be doubled. There are four times more 

 trees to the acre and the expenses of incisions are reduced by 

 one-half. 



"In the same way as I recommended Mexican planters to 

 cultivate our own Castilloa in preference to Ceara and Para, so 

 do I today forcibly recommend the cultivation of these two 

 new varieties. I have shown all the advantages as to soil, 

 cultivation, tapping and yield. With these two new varieties 

 there will be produced high yields of rubber in many large 

 districts of Mexico where it has been impossible to cultivate 

 other varieties to advantage. The subject appeals to the in- 

 habitants and property owners of the districts along the Isthmus 

 of Tehuantepec and the Pacific coast from Salina Cruz to 

 Tonala." 



