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product, which they call hurnlan, to say the least, is corrupt
(pp. 211-12).
Of great importance is his calculation of relative weights and volumes
and specific gravities, which has engaged the attention of discerning
scholars. Long back, Krenkow had observed:
No other work in Arabic or Persian of which I have knowledge treats
the subject in such a scientific manner, and as a rule other works
made no pretence of investigating the specific weights, hardness and
probable origin of the precious stones and minerals discussed. (The
Chapter on Pearls),
Of all the books on jewels and mined stones Beruni's book enjoys
superiority in that he has established the specific gravity of most of
the stones and jewels he has described. It is only through the knowledge of the specific gravity of stones that imitation can be detected
and the precious stones saved from imitation. (Khatima at the end
of the Arabic ed.).
More recently, attention was called particularly to the "scientific problems raised by al-Biruni" in this work — viz. the origin of minerals and
metals, growth of minerals and the progressive formation of metals, and
the determination of specific gravity of metals and minerals. (Anawati,
G. C.: The Kitab al-Jainahir, Al-Biruni Commemorative Volume, Hamdard Academy, Karachi, 1979).
In view of all sorts of tales and claims about quality and purity of
precious stones and metals, Beruni saw the need for devising a scientific
method whereby genuine metals and gemstones could be distinguished
from the corrupt ones and, also the comparative degree of excellence of
each could be precisely established. The idea of standard weights and
specific gravity had dawned upon him, and he sat down to prove it
experimentally. Thus, he devised a 'specific gravity flask' and operating
it in combination with his 'Water Balance' he determined relative weights
and specific gravities of different metals and minerals.
All this has not been elaborated by Beruni in Kitab al-Jamahir, but
on the basis of his experimentation and verification, he has given relative
weights of a number of metals and minerals and also made other relevant
observation as under:
(a)   With gold as the axis [qutb) having the standard weight of 100,
the relative weight, with equivalence in volume, of mercury =
71 (p. 199), tubal iron 41-1/3 (p. 215), copper = 45-2/3 (p. 211),
shibh (yellow copper) = 44-7/8 (p. 225), lead = 60-1/8 (p. 221).
(b)  With ghubari ruby as the axis (qutb) having the standard weight
of 1 00, the relative weight, with equivlance in volume, of the red
ruby = 97-1/8 (p. 64), bussad 64-13/24 (p. 166), lapiz lazuli =
67-7/12 (p. 168), emerald 79-1/2 (p. 142), Subaj (about) = 28 (p.
xv