ED
set of 24 touch needles. (Basle, 1556). Woodcut.
A set of 24 touch needles. These were made of the purest obtainable gold and each was alloyed with different known amounts of silver and copper, or of both. The sample of gold to be tested was rubbed on a hard dark stone, and the colour and thickness of the trace left was matched by one of the touch needs and the value of the sample obtained. From 'De re metallica', by Agricola, pseudonym of Georg Bauer (Basle, 1556). Woodcut.
Details
ID
161765935
Collection
License type
Editorial
Photographer
Creation date
04-06-2021
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