Another was hunch-backed and dressed in heavy robes despite the heat of the day, and a third man barely taller than her had white irises and silvering hair.
Sirian edged closer, his wise gaze and silvering hair the only signs of aging on his otherwise lean frame.
These three adjustments having been made, the prisms P3 and P4 are removed and replaced by another prism in which the silvering is arranged as in fig.
The principle of applying metallic films to glass seems to have been known to the Romans and even to the Egyptians, and is mentioned by Alexander Neckam in the 12th century, but it would appear that it was not until the 16th century that the process of " silvering " mirrors by the use of an amalgam of tin and mercury had been perfected.
The brightness of the image is sometimes in creased by silvering the glass; and on removing a small portion of the silver the observer can Object see the image with part of the pupil while he sees the paper through the unsilvered aperture with the remaining part.
Tin amalgam is used for "silvering" mirrors, gold and silver amalgam in gilding and silvering, cadmium and copper amalgam in dentistry, and an amalgam of zinc and tin for the rubbers of electrical machines; the zinc plates of electric batteries are amalgamated in order to reduce polarization.
Formerly the fur was only used for hatters' felt, but with the rise in prices of furs these skins have been more carefully removed and-with improved dressing, unhairing and silvering processes-the best provides a very effective and suitable fur for ladies' coats, capes, stoles, muffs, hats and gloves, while the lower qualities make very useful, light-weighted and inexpensive linings for men's or women's driving coats.