114 



THE INDIA RUBBER WORLD 



[January i, 1903. 



Caoutchouc scraps, with dilute alkali solution — for example, a 

 3 per cent, caustic lye solution — to tne action of great heat, for 

 instance, 173.5^ C, for some time, say 20 hours, in a closed re- 

 ceptacle. The finely disintegrated (ground or rubbed up) rub- 

 ber waste is placed in a suitable vessel with diluted alkali solu- 

 tion (3 per cent, caustic soda solution) in sufficient quantity to 

 penetrate the rubber and cover it. The vessel is closed, heated 

 to about 173.5" C. by means of steam and the temperature is 

 maintained for 20 hours. The smaller the quantity of sulphur 

 contained in the rubber, the less heat and the shorter a time 

 of action of same is required. For a practical process aiming 

 at the reclaiming of vulcanized rubber scraps of various origin 

 such as occur in commerce, the temperature of 173.5° C. (equal 

 to the temperature of steam at 8.8 atmospheres) has been found 

 suitable for a duration of 20 hours. Devulcanization and at 

 the same time destruction of the texture which contains the 

 scraps is thereby accomplished. The product is washed out 

 perfectly to remove the lye. Tolerably good results are ob- 

 tained with rubber containing a slight percentage of sulphur, 

 at a steam pressure of 6.3 atmospheres. Very good results 

 were obtained with 12.3 atmospheres. 



One of the processes mostly in use for the regeneration of 

 old rubber consists in treating it. in the ground state, with soda 

 lye. under pressure, then washing twice thoroughly, and drying 

 in the vacuum. The object of the washing on the cylinders. 



etc., is to eliminate the lye. The carefully dried waste is mixed 

 with 5 to 10 per cent, benzol or mineral oil on cold rollers and 

 then steamed under pressure for some hours at 4 atmospheres ; 

 the product obtained is worked out between cylinders and min- 

 gled with the various mixtures of rubber. The boiling of the 

 ground waste with rosin oil has been abandoned entirely, be- 

 cause the product obtained was found to be smeary, irregular 

 and partially permeated with hard pieces. 



Floating scrap, and especially scrap from elastic threads, is 

 finely ground and mixed with 20 per cent, benzol, pressed hy- 

 draulically in cylinder molds; these closed molds are vulcan- 

 ized 6 hours in boiling sulphur at 141; to 1 50" C, whereupon the 



somewhat viscuous product is rolled out into sheets. 



* * ♦ 



The foregoing article shows in a marked degree the status of 

 the business of reclaiming rubber in Germany, and as viewed by 

 a distinguished Teutonic expert. In many portions the state- 

 ments will not coincide with the experience of the English and 

 Americans. Scrap prices which vary from 11 to 65 cents a 

 pound will be a stumbling block to all but the most credulous, 

 but need not after all be taken as serious market quotations. 

 The inference that old boots and shoes are of little value 

 abroad is also a bit off the track. The article, however, is in- 

 teresting and worth the space which it occupies in these pages 

 — The Editor. 



RUBBER PLANTING AND EXPLOITATION. 



Dates 



June 1897 



N0V.-DCC..1898 

 April-Mav.1899 

 Nov. -Dec . 1899 

 Oct.-Nov . 1900 

 Aug. -Sept. 1901 

 Oct.-Nov.. 1902 



Total 



Lbs. Oz. 



YIELD OF A ''para RUBBER" TREE IN PENANG. 



A RUBBER tree from Patd seed in the Waterfall botanic 

 garden, Penang (Malay states), now 17 years old, has had 

 seven tappings, beginning in [une, 1897, the total yield 

 from which, in dry rubber, is herewith stated in detail, as 

 reported by Mr. C. Curtis, superintendent of the garden, to the 

 Straits Agricultural Bulletin. The aggregate is 18 pounds T\i 

 ounces ; an average per tapping of 2 pounds 10.18 ounces, or an 

 average per year of 3 pounds 1.21 ounces. The system of tapping 

 is thus described : A small perpendicular channel is cut in the 

 bark about a foot in length and ,'s inch broad, but not deep 

 enough to obtain much/rt/^.r, its object be- 

 ing merely to conduct the/a/^.r to a tin re- 

 ceptacle fastened at its base. This channel 

 is not subsequently enlarged or interferred 

 with. Two or three incisions are then cut 

 on either side, leading obliquely to this 

 channel to supply this latex. From the 

 upper side of each of these a thin shaving of bark is removed 

 every morning, or on alternate mornings, which causes a fresh 

 flow of late.x. In each of these seven tappings a thin shav- 

 ing has been removed thirteen times, which, with the initial 

 cutting, makes fourteen operations, the whole constituting 

 what Mr. Curtis calls one tapping. Thus 

 the number of times this tree has been op- 

 erated upon is 7 X 14=98. and average 

 amount of dry rubber from each operation 

 about 3 ounces. The daily amount, however, 

 varies very much, the yield from the first 

 two or three operations each season being 

 almost nil. No attempt was made, until 

 the last tapping, to save such rubber as may 

 have been removed with the shavings of bark referred to, and 

 this, Mr. Curtis thinks, would be an important item in a large 

 plantation. A plain carpenter's chisel is considered better 



13-^5 



7-25 



LAN OF INCISIONS. 



than a special tapping tool sent to Mr. Curtis, because a finer 

 edge can be kept on it, and the sharper the implement the 

 better the flow and the less the loss by coagulation in the cuts. 



This tree resulted from seed planted in the Singapore botanic 

 garden in 1885, and was one of a dozen transplanted in Penang 

 early in 1886. It was selected for the series of tapping experi- 

 ments on account of being the largest in the group. " It is not 

 pretended that the result of tapping the tree is of great value 

 as a guide to the results to be obtained from a large number, 

 for we now know," says Superintendent Curtis, " that there is 

 a great dissimilarity in the yield of trees of equal size growing 

 side by side and under exactly similar conditions. The interest 

 in this particular tree, then, is that it has been tapped six times 

 . . . that it shows no sign of deterioration, that the incisions 

 made are all healed up, and that the total yield of dry rubber 

 during that period " is as stated. Two years ago this tree was 

 55 feet high and 66 inches in girth at three feet from the ground. 

 At y/z feet from the ground the tree branched into two stems, 

 with a girth respectively of 44 inches and 34 inches, five feet 

 above the ground. 



AN OFFICIAL VIEW OF RUBBER CULTURE. 



The annual report of the United States secretary of agricul- 

 ture for the year ended June 30, 1902, says : 



" It is generally supposed that a continuously humid climate 

 is necessary for rubber culture, but in southern Mexico it is ob- 

 vious that an alternation of distinct wet and dry seasons is fa- 

 vorable to the production of rubber by Castilloa, which will 

 permit a much wider use of this tree in our tropical islands than 

 has appeared possible hitherto. The failure of some of the 

 earlier experiments may be ascribed to planting in situations 

 too uniformly moist. The tree will often grow luxuriantly 

 where it will produce little or no rubber, as many planters have 

 learned to their cost. Rubber is the most important vegetable 

 raw material now imported for manufacture in the United 

 States. The agricultural production of rubber is assured, and 



