Dr Maclagan on Gutta Percha. 239 



H.E.I.C.S., whose spirited exertions to improve the cultiva- 

 tion of various articles of colonial produce at Singapore have 

 obtained for him several distinguished marks of approbation 

 from the Royal Society of Arts of London. For his commu- 

 nication regarding gutta percha, Dr Montgomerie received 

 a silver medal from the Society. 



This substance, in its crude state, differs, in many particu- 

 lars, from common caoutchouc. It is of a pale-yellovs^ish, or 

 rather dirty-white, colour. It is nearly as hard as wood, 

 though it readily receives the impression of the nail. It is 

 very tenacious, and not at all elastic. 



It seemed to me to be worth while to determine, whether 

 or not this substance really was a variety of caoutchouc, and 

 for this purpose I subjected it to the ordinary process of ulti- 

 mate analysis, and obtained as its per-centage composition, 

 carbon, 86'36 ; hydrogen, 1215 ; the remainder, 1'49, was 

 most probably oxygen absorbed from the air during the pro- 

 cess employed for purifying it, as the substance, whilst heat- 

 ing on the vapour-bath, acquired a brown colour. The only 

 analysis of common caoutchouc with which I am acquainted 

 is that of Faraday, who obtained, carbon, 872 ; hydrogen, 

 12-8. The results are sufficiently near to warrant the con- 

 clusion, that the two matters in question are generically the 

 same. 



I found, also, that the gutta percha yields the same pro- 

 duct of destructive distillation as the common caoutchouc. 

 Without entering into details, I may briefly state, that both 

 equally yield a clear, yellow, limpid oil, having no fixed 

 boiling-point, and, therefore, being a mixture of different 

 oleaginous principles. In both instances, the distillation 

 proceeds most freely at temperatures between 360° and 390" 

 Fahr., and seems almost stationary at 385°. Comparative 

 analysis of similar portions of the two oils were made, and, 

 as is already known of common caoutchouc, the products 

 exhibit a constitution represented by the formula do Hg. 

 1 he gutta percha thus appears really to be a modification of 

 caoutchouc. 



In its general properties it likewise shews a similarity to 

 common caoutchouc. It is soluble in coal naphtha, in caout- 



