132 
ON GUTTA PERCHA. 
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 ultimate analysis, and obtained as its per-centage compo- 
sition, — carbon, 86-36; hydrogen, 12*15; the remainder, 1-49, 
was most probably oxygen absorbed from the air during the 
process employed for purifying it, as the substance, whilst 
heating on the vapor-bath, acquired a brown colour. The 
only analysis of common caoutchouc with which I am ac- 
quainted is that of Faraday, who obtained, carbon, 87*2 ; 
hydrogen, 12-8. The results are sufficiently near to war- 
rant the conclusion, 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 enteriug into details,! 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° F., and seems almost stationary at 385°. Compara- 
tive analysis of several portions of the two oils were made> 
and, as is already known of common caoutchouc, the pro- 
ducts exhibit a constitution represented by the formula 
C 10 H 8 . The gutta percha thus appears really to be a mo- 
dification of caoutchouc. 
In its general properties it likewise shows a similarity to 
common caoutchouc. It is soluble in coal naphtha, in 
caoutchouc oil, and in aether. It is insoluble in alcohol and 
in water, and floats upon the latter. 
Its most remarkable and distinctive peculiarity is the ef- 
fect of heat upon it. When placed in water at 110°, no 
effect is produced upon it, except that it receives the impres- 
sion of the nail more readily ; but when the temperature is 
raised to 145° or upwards, it gradually becomes so soft and 
pliant as to be capable of being moulded into any form, or 
