Gums, Resins, 



108 



[August, 1909. 



the length of time which must elapse 

 before the trees become productive. 

 Thjre is all the more reason for the 

 Dutch Government to undertake this 

 work in the fact that gutta-percha trees 

 occur naturally over so small an area, 

 and that embraced principally in the 

 Dutch possessions. There is now being 

 laid a cable, insulated with gutta-percha, 

 between Germany and Brazil to be one 

 of the longest cables in the world, and 

 there is no indication that tbe age of 

 cable building is passing. Ultimately, 

 at the present rate of consumption, 

 there will be no forest gutta-percha, and 

 all the activity of the Dutch govern- 

 ment and such private enterprise as it 

 may inspire can hardly lead to over-pro- 

 duction of this important material when 

 the world's need for it becomes acute. 



It is true that gutta-percha trees 

 under cultivation may mature at an 

 earlier age than where they are scat- 

 tered in forests, just as has proved true 

 of Hevea rubber in Ceylon and Malaya. 

 The fact is also important that science 

 has demonstrated the possibility of 

 obtaining gutta-percha from young 

 trees. The most important substitute 

 for gutta-percha yet known is balata, 

 of which important native resources 

 still exist, and in connection with which 

 some facts are given in a brief article 

 which follows. 



GUAYULE RUBBER, I. 



By Theodore Whittelsey. 



(From the Journal of Industrial 

 Engineering Chemistry, Vol. I., No 

 ' April, 1909.) 



and 

 4, 



It has long been known that the natives 

 of Mexico in some of their games use 

 balls composed of an elastic substauce 

 which they obtain by chewing the bark 

 of a shrub called Guayule. Attempts 

 have been made from time to time to 

 introduce this substance industrially, 

 but without success until recently. The 

 first practical experimentation on a 

 commercial scale seems to have been 

 made in 1903-4. In the following year 

 the product, which has been found to be 

 a true rubber, began to be put on the 

 market. From this time on the industry 

 developed with extraordinary rapidity, 

 and the excitement in northern Mexico 

 is said to have been comparable to that 

 in Texas when the oil fields were dis- 

 covered. By 1906 practically all the 

 Guayule Avithiu reach of existiug trans- 

 portation facilities was contracted for. 



The Guayule, Parthenium argentatum, 

 is found on the semi-arid lands of the 

 plateau of northern Mexico, growing in 



the dry, rocky soil of the foot-hills. It 

 is not large ; the dimensions of plants 

 of factory size are approximately as 

 follows : — 



Height. Dry weight, Diam f t e r ^ base 



12 inches 6 ounces $ inches 

 20 „ 12 „ H „ 



86 „ 32 ., 2| „ 



The acreage weight of factory shrub 

 is probably between 12 and 16 ounces. 

 The plant shown in the cut is an excep- 

 tionally large one, weighing 5| lbs. It 

 was 44| inches high and 2j inches in 

 diameter at the ground level. 



The shrub is collected by pulling up 

 the entire plant, and is pressed either in 

 the field or at the railway station into 

 bales weighing from 80 to 120 kilos. In 

 1904 these are said to have brought 

 7 pesos* per ton ; in 1905 the price had 

 risen to 30 or 40 pesos, and recently has 

 been above 100 pesos. 



The Guayule contains in the neighbour- 

 hood of 9 per cent, of pure rubber, 

 calculated to the perfectly dry plant. 

 The methods that may be used to extract 

 the crude rubber are entirely different 

 f rom those used with most rubber plants. 

 These contain a milky juice or latex 

 from which the rubber is obtained by 

 coagulation, while in the Guayule the 

 rubber exists as such preformed in the 

 plant. The earlier processes were of 

 three types : (1) the alkali process, in 

 which the shrub was boiled with a 

 solution of caustic alkali ; (2) the solu- 

 tion processes in which the rubber was 

 extracted by carbon bisulphide or some 

 other solvent ; and (3) the mechanical 

 process. The first of these is still used 

 in apparently only one factory. Accord- 

 ing to the patent specifications, the 

 ground shrub is boiled with three times 

 its weight of 6 per cent, caustic soda for 

 six hours, after which the rubber is 

 skimmed off and freed from alkali. Of 

 the second class, the carbon bisulphide 

 method has been abandoned, because of 

 the expense and the belief that rubber 

 when recovered from a solvent does not 

 possess certain desirable physical quali- 

 ties to the same degree as an undissolved 

 rubber, A process that belongs to this 

 type has been extensively experimented 

 with in a new factory during the past, 

 two years. This process is said to be 

 based on the extraction of the dried 

 shrub with benzol. A solution of rubber 

 and resin is obtained, from which the 

 former is pecipitated by the addition of 

 alcohol. It has been prophesied that this 

 process will prove a failure for the same 

 reasons that have led to the abandon- 

 ment of the bisulphide extraction, but 

 the product is now on the New York 



* peso = $0"50 gold, 



