ultima ratio regis
[Ge].
‘The king's final argument’, an inscription commonly found on Spanish royal cannon.
ultra-violet visible spectrophotometry
(uv-vis)
[Te].
A method for determining the chemical composition of materials. Based on the same principle as
AAS
, a beam of light is passed through a sample such that the amount of light absorbed is proportional to the concentration of the chemical under investigation. It can be used either to scan through a range of wavelengths from the ultra-violet to the visible or to analyse at one wavelength. Typical applications include the analysis of phosphates in soil extracts (where the phosphate is made to form a blue-coloured complex which absorbs in the visible region), the determination of iron and aluminium levels in soil, or the chemical composition of ancient glass.
Umayyads
[CP].
First dynasty of Arab leaders, the descendants of a Meccan merchant who submitted to Muhammad . They seized power in ad 661 and maintained a system based on that of the nomadic desert tribes until split by internal feuds and the rise of the Persian
ABBASIDS
in ad 750.
umu ti
[Co].
Kind of earth oven found in the South Island of New Zealand.
unchambered long barrow
[MC].
undercroft
[Co].
A vaulted subterranean room or basement usually wholly or partly under a larger building. Commonly used in medieval times as secure storage for goods and commodities by traders and merchants.
understanding
[Th].