References in Khazini's Mizan al-Hikmat indicate that Beruni had
continued his specific gravity experiments after his advent and settlement in Ghaznah, Here he had brought more of metals and liquids under
study, and increased the unit mass from 100 mithqal to 'one cubit cube'
to determine relative weights. Recounting the history of the 'water
balance' and its use by scientists from early times, Khazini says in the
introduction to his book that during the rule of the 'House of Nasir alDin (i.e. the Ghaznavid Sultan Mahmud and his successors), the balance
was used with expertise by Abu Rayhan (Beruni)
"who took observations on the relations of (different) metallic
bodies and precious stones, one to another, as indicated by this
balance, and carried his deductions so far as to distinguish one from
another (in a compound), exactly and scientifically, without melting
or refining, by arithmetical methods."
This interesting observation shows that in the 6th/12th century Central
Asia, when Khazini wrote in Merv, the practice of determining the
degrees of purity of gold by melting and refining was common and
known, though the practice was not a scientific one. In much later times,
one such practice known as banwari which had been developed in India
by the experts in the Imperial Mint of Emperor Akbar (1556 — 1605
A.H.), has been explained in detail by Abu'l Fazl in The A'in-i Akbari
[Eng. tr. by H. Blochmann, ("A'in 6: Banwari, pp. 19-20"), The Asiatic
Society of Bengal, 2nd ed., Calcutta, 1927].
In Chapter IV of the Third Part, Khazini has described one of
Beruni's experiments in Ghaznah in which he used a 'cubit cube' as the
standard unit of volume/weight instead of 100 mithqals as before:
Abu Rayhan ordered a cube of brass to be made, with as much exactness as possible, and that it should be bored on its face, at two opposite angles, with two holes, one for pouring water into it, and the
other for the escape of air from it; and he weighed it in the flying
balance, first empty and hollow, then filled with fresh river-water of
the city of Ghaznah. . . . etc. etc.
Khazini took this from Beruni's Maqalah, but he had also used Beruni's
Kitab al-Jamahir from which he only summarized (under Part IV, Chapter 10) Beruni's observations on eight precious stones. It is also clear
from the present text of K. al-Jamahir that Beruni has not described in it
any of his experiments based on 'cubit cube' as a unit. However, he has
cited the following one result which is based on the value of a cubit
cube:
Weight of a cubit cube of water is one nineteenth part of a similar
cube of gold (p. 204).
This was most probably determined by him in the experiments which he
conducted in Ghaznah.
