Feb. 1908.] 



103 



Saps and Exudations. 



Commercial Value.Ss. 6d. per lb. in 

 London. The current price of fine hard 

 Para from South America was 5s. 2d. 

 per pound. 



Remarks.— The sample has the usual 

 appearance of Landolphia rubber ; it is 

 of very fair quality, though the amount 

 of insoluble matter is rather high. This 

 defect could be remedied by careful 

 collection, so as to exclude, as far as 

 possible, fragments of bark from the 

 rubber. 



Consignments of this rubber, if well 

 prepared, would be readily salable at 

 satisfactory prices. 



Since the above was written a speci- 

 men of Mascarenhasia elastica has been 

 received from the Uganda and British 

 East Africa Exploration Syndicate, 

 accompanied by a short note by Mr. 

 Henry Dalziel, who reports : — " The en- 

 closed specimens of leaves, fruit, and 

 wood are from a new kind of rubber 

 tree, lately discovered by the natives in 

 Wanga District, British East Africa, 

 and called by them " Goa." This tree is 

 generally found on the banks or near 

 the sides of running streams where its 

 root can get easy access to the water. 

 The steins are from a few to 18 inches in 

 diameter, and form a bole 20 feet high to 

 where it branches out. In old trees the 

 bole has generally a great number of hol- 

 lows, with a rough scaly bark which 

 can easily be rubbed off ; the inner bark 

 is a quarter of an inch thick, and easy to 

 cut. When the tree is cut the latex 

 oozes out very slowly." 



A specimen of the wood of Masca- 

 renhasia elastica from the Wanga Dis- 

 trict, collected by Mr. H. Dalziel, is exhi- 

 bited in Case 78, Museum No I.— Royal 

 Botanic Gardens, Kew Bulletin of Miscel- 

 aneous Information, No. 7, 1907. 



GUAYULE RUBBER. 

 (Parthenium argentatum, A. Gray.) 

 By J. M. Hillibr. 



Among the plants of economic value 

 belonging to the natural order Com- 

 posite none are more interesting than 

 those known to contain rubber or a sub- 

 stance analogous to rubber. During the 

 last decade considerable attention has 

 been directed to two such plants of this 

 order, viz., the Colorado Rubber Plant 

 (Hymenoxys sp.), a note on which ap- 

 peared in Kew Bulletin, 1906, No. 6, pp. 218, 

 219, and the Gnayule of Mexico, tli9 sub- 

 ject of the present note. The first 

 communication received at Kew on the 

 subject of Guayule was from the Mexican 

 Land and Colonization Co, Ltd., 4, Moor 



ate Street, E.C, dated 29th December, 



1902, requesting information regarding 

 the following extract from Circular No. 

 28 issued by the United States Depart- 

 ment of Agriculture: — 



" An illustrative instance of the 

 dangers likely to beset investments in 

 rubber comes to hand as this Circular is 

 being sent to the printer. A well-known 

 Journal* notices a new substitute for 

 rubber, describing it as a gum obtained 

 by grinding up the bark and 'compara- 

 tively hard wood ' of a ' small acrubby 

 bush,' and then macerating in gasoline 

 or other hydrocarbon solvent. ' By this 

 process the gum that comes out is chemi- 

 cally pure and suitable at once for 

 manufacture, and it forms a new com- 

 position consisting of resin of the plant 

 combined with a residual portion of the 

 hydrocarbon solvent.' The shrub, which 

 has no milky juice, is said to grow in 

 abundance on the ' rolling land ' of 

 Central Mexico, is really propagated, 

 may be cut two or three times a year, 

 may be treated when fresh, or dried for 

 export, and yields by weight forty per 

 cent, of a gum ' superior to most india 

 rubber,' and having the additional 

 advantages of abundance, cheapness and 

 ease of manipulation. 



" The Indian name is said to be ' Yule' 

 already known 'in application to Castil- 

 loa, while the scientific designation 

 Synathereceas Mexicanus, seems K^to 

 have been unfortunately chosea, since 

 the genus Synantherias, which has the 

 only similar name known 'to botanists, is 

 a member of the Aroid family. ' More- 

 over it is by no means clear how the 

 ' comminuted shrub ' without other 

 provision than straining through a can- 

 vas bag, for the separation of the 60 

 per cent, of waste matter, can be ex- 

 pected to issue in the ' chemically pure ' 

 condition, since the oils, fats, resins, and 

 many other vegetable substances would 

 be.ineorporated by the solvent. Neither 

 could such a process be carried out on 

 fresh material, the water of which would 

 prevent the action of the solvent. 

 Similar ''inaccuracies are frequent in 

 claims and i applications for patents for 

 artificial rubber substitutes, the published 

 accounts of which are sometimes intend- 

 ed to draw public attention without 

 unduly enlightening trade competitors. 

 Naturally the knowledge of any such new 

 source of wealth, or of a process by 

 which a hitherto worthless natural 

 product may be exploited, generally 

 results in the greatest secrecy on the 

 part of the first possessors of the infor- 

 mation.' The passage doubtless refers 

 to the Guayule, the name Syna- 

 thereceas Mexicanus being probably 



* "Scientific American," 



