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Specific Gravity Flask".
Besides the shape of the flask, some other factors which caused variations in results were also detected by Beruni. The one was the absolutecleanliness of the metal/mineral and purity of the water used, and the
other, a more subtle one, temperature of water. Beruni knew that temperature influenced the density of water, and of other liquids: and he had also determined it that difference between the density of cold ard hot water was 0.041677 (N. Khanikoff, p. 80). Beruni, therefore, sounded the warning that in the kind of experiments conducted by him to determine specific gravity, it was but necessary to control the water factor, because of the changes occuring in water due to its different sources and courses, and the temperatures to which it was subjected during the four seasons, 'on the analogy of air'. "Therefore", he says, "in all our experiments we used the water drawn from one fixed place from the Oxus river adjacent to Jurjaniyah, in the beginning of the autumn (kharif) season". However, he also explained the general principle that even the ordinary drinking water was good enough provided the same water under the same conditions was used while experimenting with different metals and minerals. And yet, the scientists after Beruni kept following him faithfully — not only in their careful use of the balance but, as Khazini informs, they also related the process of finding the specific gravities "to a determined sort of water, similar in density to the water of Jayhun of Khwarazam, exclusively of other waters." (Mizcin al-Hikrnat, p. 70 & Introduction, Section 5) Beruni's keen observation, insights and understandings, and his
ability to design and refine his apparatus, contributed to the success of his experiments in determining the specific gravity of gemstones, metals and other minerals with remarkable accuracy. In his study (Jr. Asiatique, XI, 1858), J. J. Clement-Mullet produced a Table of comparative figures of specific gravities for 18 metals/minerals as given by Beruni with modern figures (in 1858) to show the remarkable accuracy of Beruni's calculations. Subsequently, H. C. Bolton also gave modern figures in his study in 1 876 as in the following Table. The scholastic Sa'd al-Din Taftazani's concise and interesting description of Beruni's experimentation in Jurjaniyah, Khwarazm, may be
noted: In order to determine the comparative difference between metals
and some stones from the point of volume, lightness and heaviness. Abu Rayhan had devised a vessel resembling the tabarzad, on the neck of which was mounted a curved tube (mizab), as it is in abariq (flasks). He filled the vessel with water and put into it one hundred mithqal (of a given metal/mineral) — say of gold. Below the tip fras) of the mizab, he placed one pan of the balance (to hold water) |
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