The varnish to fix the webs is applied, not on the surface T as is usual, but on a bevel for the purpose,' the position of the webs depending on their tension to keep them in their furrows.
Repsolds' more recent form of the spider-line micrometer (since 1 The marks of varnish so applied will he seen in fig.
Heated rather below 300° C. amber suffers decomposition, yielding an "oil of amber," and leaving a black residue which is known as "amber colophony," or "amber pitch"; this forms, when dissolved in oil of turpentine or in linseed oil, "amber varnish" or "amber lac."
Impurities are often present, especially when the resin dropped on to the ground, so that the material may be useless except for varnish-making, whence the impure amber is called firniss.
Small fragments, formerly thrown away or used only for varnish, are now utilized on a large scale in the formation of "ambroid" or "pressed amber."