152 ON THE CHEMICAL PROPERTIES OF SILK. 
its chemical properties changed, that by the addi- 
tion of half the original portion of muriatic acid, 
the liquid might be employed for a first immersion 
of the raw silk. 
The bleaching operation was completed by pour- 
ing upon the silk forty-eight pounds of pure spirit 
of wine, which was allowed to remain from twenty- 
four to thirty hours on the silk. There is great 
difficulty in freeing the muriatic acid from the silk, 
which can only be effectually done by subjecting it 
to a continued stream of running water for some 
hours.* 
In England a different process is pursued, which 
is by immersing the silk in a solution of soap in 
river water, while it is kept at the boiling point for 
two or three hours; when it is taken out, well 
beaten either with a machine constructed for the 
purpose, or with a wooden mallet, and afterwards 
washed in river water. It is then wrung, and 
again immersed in soap and water, in a cold state, 
with the addition of a small portion of indigo, and 
brought to the boiling point ; at which it is allowed 
to continue for a short time. It is then taken out, 
wrung, and shaken ; and dried in a stove construct- 
ed for the purpose, over the fumes of burning 
sulphur, which render it of the most beautiful 
whiteness. 
* See Ure’s Dict. of Chemistry, article Bleaching, for a 
more full detail of this process, 
