—— —— friction
—— —— heat
—— —— chemical cleansing ,
—— clean, their general properties
—— their power preserved
—— —— in water
—— their power diminished by action
—— —— exposure to air
—— their power affected by washing in water
—— —— heat
—— —— friction
—— —— heat
—— —— chemical cleansing ,
—— clean, their general properties
—— their power preserved
—— —— in water
—— their power diminished by action
—— —— exposure to air
—— their power affected by washing in water
—— —— heat