Erasmus+ 68
H2SO4
It doesn’t melt
H2SO4 conc. melts. Medium concentration ripples (all animal fibers, except wool, dissolve in 1-2 hours)
It carbonates completely and faster than animal fibers
They are easily attacked even by diluted acids
HNO3
It affects the fiber even if it is cold, coloring it first in yellow
It melts completely in a few minutes and it turns yellow and slowly melts
forming a yellow solution
It doesn’t melt, and it doesn’t get colored
They are easily attacked even by diluted acids
NaOH 10%
(let it boil
for approx. 30 ')
It melts when it’s hot and if you add some drops of blue lead acetate to the boiling beaker
It melts when it’s hot and if you add a few drops of lead acetate to the boiling beaker
It’s more resistant to the attack
It remains unaffected
SCHWEITZER’s reagent
It doesn’t melt but it gets colored
It melts
It melts quickly
Wool
Silk
Cotton
Synthetic fibers
FLAME’S BEHAVIOUR
It burns slowly with a slight crackle. The combustion ceases as soon as you move away from the flame. It doesn’t emit fumes but gives off the smell of burnt hair. The residue is voluminous, porous, carbonaceous, fragile and it easily shatters dirtying the fingers (very fine black powder)
It burns slowly with a distinguishing smell of burnt flesh (less intense than the wool)
Approached to the flame it burns easily. The flame is sustained and there is no emission of fumes.
The smell is similar to paper because it burns cellulose. The residue at the end of the combustion is scarce, light, of generally light color (for the linen the fumes are yellow)
It burns with thick and acrid smoke and with greenish flame.
They tend to melt, and they are hard to turn off even when you move away from the flame