150 
ON THE CHEMICAL PROPERTIES OF 
SILK. 
Tur rich yellow colouring matter which tinges 
all silk, more or less in its raw state, is’ in combi-. 
nation with{the gum. Immersing the cocoons in 
hot water will dissolve, to a certain extent, this 
gum, and leave a yellow tinge in the water. But 
the use of alcohol instead of water, will dissolve 
this matter in greater quantity. This tincture will 
retain its colour with little loss of intensity, even 
after being long exposed to the rays of the sun. 
The fact of this affinity of the colouring matter of silk 
for alcohol, suggested to Mons. Baumé the idea of 
bleaching silk in the following manner. 
He constructed a twelve gallon stoneware vessel, 
of a form nearly conical, with a wide opening at 
the top, and a smaller one, of about an inch in 
diameter, at the bottom, which was stopped by a 
cork ; through the centre of which was passed a 
glass tube, of a quarter of an inch diameter. This 
tube was always stopped by a cork, except at the 
time wken the liquid required to be drawn off. 
The inside of the vessel was polished very smooth 
with pumice-stone, to prevent the roughness from 
breaking the threads in their first state. 
