1876.] The Book of the Balance of Wisdom . 511 
ties,* are found below. For sake of comparison, we also 
annex the figures obtained by Abu-r-Raihan, from whom it 
is believed al-Khazini quotes ; the slight discrepancies are 
largely due to different methods of calculation adopted by 
Clement-Mullet and Khanikoff. 
Al-Khazinfs First Table of Specific Gravities. 
Substances. 
Al-Khazini. 
Abu-r-Raihan. 
Modern Authorities. 
Gold [cast] 
• I 9'°5 
19-05 
I9*30 
Mercury 
• I3'5 6 
I3-58 
I3T9 
Lead 
• n\33 
11 *33 
11*34 
Silver 
. 10*30 
10*35 
10*52 
Bronze . 
8*82 
8*82 
8*05 to 8*95 
Copper . 
. 8*66 
8*70 
8*78 
Brass . . 
• 8-57 
8'57 
8-58 
Iron (forged) 
• 774 
774 
779 
Tin . . . 
• 7'32 
7‘3 I 
7-29 
It is interesting to learn that the Arabian physicists fully 
appreciated the necessity of operating on pure materials, 
and the advantages of averaging the results of many deter- 
minations. 
Thus al-Khazini says he purified gold by melting it five 
times, after which it melted with difficulty, solidified ra- 
pidly, and left hardly any trace upon the touchstone ; and, 
after ten trials to obtain the weight of the volume of water 
displaced by different weights of the gold, he found, for a 
hundred mithkals of gold, weights varying from 5 mithkals 
1 danik and 1 tassuj to 5 mithkals 2 daniks ; as mean weight 
he adopts 5 mithkals 1 danik 2 tassujs, which by calculation 
yields the figures in the preceding table. 
Likewise mercury was purified by passing it repeatedly 
through many folds of linen cloth. In writing of mercury, 
he remarks that it is not, properly speaking, a metal, but it 
is “ the mother of the metals, as sulphur is their father.” 
This view of the nature of mercury was prevalent among 
Arabian chemists, and is found in the writings of Geber (or 
Djafar), who lived four centuries earlier. Geber writes of 
mercury — “ It is also (as some say) the matter of metals 
with sulphur,”! and he does not place it in the same class 
with metals which he defines as “ extensible under the 
hammer,” a property not possessed by mercury under ordi- 
nary conditions. 
* Cf. Prof. F.W. Clarke’s Tables of Specific Gravities, &c., in Constants of 
Nature, Part L, Smithsonian Miscellaneous Collections, 1873 , 8 vo. 
t Geber, Sum of Perfection, Book I., Part III., Chap. 6 . 
