460 ON GUTTA PERCHA, &C, 
reaction disappears, and seems, consequently, to proceed from 
some volatile organic acid. On being evaporated, a brown 
extract-like substance remained behind, which precipitates from 
the watery solution upon the addition of alcohol. Its quantity 
is very insignificant; in the specimen b it amounted, after 
three times boiling in water, to 0.042 per cent, of the weight of 
the gutta. That the gutta becomes discoloured by being boiled 
in water the author did not find corroborated ; on the contrary, 
it preserves its former colour. The specimen b imparts to 
the water neither colour nor acid reaction. Also from lump 
caoutchouc no ponderable quantity was extracted by water. 
Gutta percha, treated by water and by cold alcohol, yielded 
a resin, which was soluble in ether and volatile oils: the 
quantity amounted in the sample b to 3.495 per cent. The 
gutta percha being then repeatedly boiled with alcohol, the 
latter extracted, besides an additional quantity of resin, also a 
white fat, resembling wax, amounting to 12.035 per cent. The 
sample c yielded no perceptible quantity of resin, and but a 
small proportion of fat. From lump caoutchouc almost nothing 
was extracted by cold alcohol : boiling alcohol dissolved a light 
yellow very viscid resin of some smell and of a bitter taste, 
whose proportion amounted to 4.772 per cent. 
After having been treated with water and alcohol, the gutta 
percha was further treated with hot ether, which extracted a 
resin much of the same smell as the gutta, and was in a of a 
dark colour, in b similar to dry grape-sugar; its proportion was, 
in b, 13.610 per cent. The sample c yielded no resin to either. 
Having thus being treated by water, alcohol, and ether, 
rectified oil of turpentine was employed, in which the gutta 
was, after a few days, dissolved into a thick somewhat brownish 
liquid, which in a diluted state could be filtered through paper, 
to remove the impurities, and was then perfectly clear. One 
part of gutta percha requires for its solution from four to six 
parts of oil of turpentine. From this solution the gutta percha 
was obtained, by adding alcohol until the smell of the oil of 
turpentine had disappeared, as a beautifully white substance, 
possessing all the properties which characterise the gutta percha. 
In the course of time, however, it assumed a darker colour, and 
became, at last, yellow like straw ; at the same time an acid 
smell developed itself similar to that of pine-resin, which 
originated very likely from some quantity of the oil of turpen- 
tine having been retained, which formed, with alcohol, acetic 
acid. 
The best means of obtaining the principal and essential parts 
of the gutta percha in a pure state is chloroform. The samples 
a and b were dissolved by it even when cold ; c required hot 
