CAOUTCHOUC. 



it- upon the wise and peaceful administration which dis- 

 tinguished the latter part of his reign. Hi- who at first 

 "*Y""" / made no scruple to wade throughthe blood of the inno- 

 cent, and set at defiance the sacred laws of religion and 

 justice, when they opposed his ambitious schemes, was, 

 in the latter part of his reign, not less remarkable for 

 his sacred regard to religion, and for the exercise of eve- 

 ry moral virtue ; insomuch, that he gained the entire 

 affection of his own subjects, and the universal esteem 

 of foreigners. We need not be surprised, however, 

 that a prince whose reign had been so prosperous, 

 the sovereign of Denmark, Norway, and England, 

 was surrounded with flatterers. Some of them, it is 

 said, carried their adulation so far, as to declare that 

 nothing in nature dared to disobey his commands. 

 Offended at their extravagant praises, and desirous to 

 make them sensible of their folly and impiety, he 

 commanded that a chair should be placed upon the 

 beach at Southampton, while the tide was advancing ; 

 and, seating himself in it, he thus addressed the ap- 

 proaching billows. " O sea, thou art my dominion, 

 and the land on which I sit is mine : I charge thee 

 not to approach farther, nor dare to wet the feet of 

 thy sovereign." Regardless of his command, the 

 waves advanced, and forced him to retire. Turning 

 to his courtiers, he addressed them in language which 

 might not be unworthy of the ears of sovereigns to 

 hear; " Learn from this example the insignificance 

 of all human power, and that the word of God alone 

 is omnipotent." Rapin's Hist, of England, vol. ii. ; 

 Hume's Hist, of England, vol. i. ; Henry's History 

 of Great Britain, vol. iii. (A. F.) 



CAOUTCHOUC, a soft, dense, elastic, vegeta- 

 ble substance, well known under the names of elas- 

 tic gum, and Indian rubber. It is remarkable not 

 only for the above characters, but also for its won- 

 derful inflammability ; and for some very singular 

 chemical and mechanical properties. In this coun- 

 try it is commonly to be purchased in the form of birds 

 and bottles of a spherical shape. 



This substance appears to have been introduced 

 into Europe about the beginning of the eighteenth 

 century ; but nothing was known of the mode of its 

 production, until the year 1736, when M. De la 

 Condamine presented a paper to the French acade- 

 my, describing the tree from which it is obtained, 

 and the mode of preparation. From De la Conda- 

 mine's statement, it appeared, that it was obtained 

 from a tree that grows in the province of Esmiraldas, 

 in the Brazils, and which is called by the natives 

 Hhevc. This tree, on being wounded, yields a 

 milky juice, which becomes inspissated on exposure 

 to the air, and forms caoutchouc. The same tree 

 was afterwards found on the banks of the Maragnon, 

 by Don Pedro Maldonado ; and in Cayenne, by M. 

 Fresnau. The death of the former of these gentle- 

 men prevented the publication of his observations re- 

 specting it. The latter read an account of it in the 

 French academy in 1751. More recent observations 

 have now determined, that caoutchouc is obtained 

 from two South American plants, the Hcevia caout- 

 chouc, and the Jatropha elastica. In South Amc- 

 Lrica, the juice, which is obtained by incision, is spread 

 over clay, moulded into the desired form, in succes- 

 sive layers, until the vessel be sufficiently thick. 

 The whole is then suspended over the smoke of 

 burning vegetable matters, which hardens and colours 

 ' 



it. Previous to this last mentioned process, the ex- 



of the vessel is ornamented by various mca; 

 When tin- whole preparation is completed, the clay s 

 mould is broken into pieces, and taken out. The 

 vessel is then fit for use. 



Besides the two South American plants already 

 mentioned, there are several others that yield caout. 

 chouc. The principal of these are, the Ficits indica^ 

 the Artocarpus intcgrifolia, and the Urceola elatlica. 

 The properties of the caoutchouc, obtained from tht 

 urceola, have been accurately examined by Mr How- 

 ison, surgeon at Prince of Wales' Island : and he 

 has determined the following facts : The thickest 

 and oldest stems of the urceola yield the largest pro- 

 portion of caoutchouc. On cutting these, a milky, 

 pungent juice exudes. On exposure to the air, a de- 

 composition takes place, and a firm coagulum, which 

 is the caoutchouc, separates from the thin portion. 

 This same effect is produced by time, when the air 

 is carefully excluded. If oxymuriatic acid be pour- 

 ed into the milky juice when first exuded, the caout- 

 chouc is precipitated, and the acid loses its peculiar 

 odour. Fourcroy supposed, that this change was 

 induced by the absorption of oxygen. Should Mi- 

 Davy's opinions be conclusive, some other source of 

 the phenomenon must be sought for. 



The chemical properties of caoutchouc have at- 

 tracted the attention of philosophers since the time 

 of Mr Macquer, who published, in the Memoirs of 

 the French Academy in 1768, an account of his ex- 

 periments on it. Although this celebrated chemist 

 determined many facts previously unknown, yet lu- 

 adopted some erroneous opinions, the fallacy of 

 which was pointed out by Mr Berniard, whose pa- 

 per contains the greater proportion of all the facts 

 now known respecting this interesting substance. 

 Fourcroy and Grossart have also contributed to our 

 knowledge of this subject. 



Pure caoutchouc, when recent, is of a yellowish 

 white colour, which changes to a smoke grey on ex- 

 posure to the air. Most commonly it is black, or 

 blackish brown, particularly that which comes from 

 South America : this circumstance is owing to the 

 smoking during the formation of the vessels. Caout- 

 chouc is tasteless and inodorous, except when heated ; 

 it then yields a faint peculiar smell. It is soft, plia- 

 ble, adhesive, wonderfully elastic and tough. Its spe- 

 cific gravity is 0.9335. 



Mr Gough took thin slips of caoutchouc, previ- 

 ously rendered pliable by being immersed in water, 

 observed the temperature, by applying these slips 

 slightly extended to the lips, and suddenly stretched 

 them, when a very sensible increase of temperature 

 took place. When allowed to relax to the original 

 degree of extension, the temperature was suddenly 

 returned. The same gentleman also ascertained, that 

 if these slips be plunged into cold water at the time 

 that thty are considerably extended, th?t they los 

 their contractile power, and retain nearly the same 

 degree of extension ; but if plunged hi'.o warm wa- 

 ter, or if kept warm for sonic time in tin hand, they 

 become again elastic. The specific gravity of caout- 

 chouc is considerably increased, by being weighed 

 when in a state of tension under water. These Tactt 

 are valuable, not only as they give new characters of 

 this substance, but as they are beautiful illustration* 

 of the theory of latent heat. See CHEMISTRY* 



