1889.] A. Pedler — Volatility of Mercury and its compounds. 167 



fourth, is a coin of the so-called Kenorano or Ooer (probably Oerki, 2nd 

 cent. A. D.), with the cross-legged sitting king on the obverse, and the 

 standing MAO on the reverse, as shown in Ariana Antiqua, pi. XIII, 

 fig. 10. All these coins are in rather indifferent preservation ; the 

 legends being nearly obliterated, though both the obverse and reverse 

 figures are well distinct. 



The interest of these coins is, that copper coins of the Indo- Scy- 

 thian kings whose rule extended not much beyond Mathura, should be 

 found so far to the East as the Benares district ; and it would have 

 been of some importance to know whether any more (and perhaps better 

 preserved) specimens of this class of coins were contained among the 

 14 seers of copper pice. 



The following papers were read — 



1. Notes on Indian Rhynchota, No. 6. Family Coreida?. — By 

 E. T. Atkinson, Esq., B. A. 



2. Note on the volatility of some of the compounds of Mercury, and 

 of the metal itself. — By A. Pedler, Esq., F. C. S. 



(Abstract.) 



The volatility of the metal mercury at ordinary atmospheinc tem- 

 peratures has already been shewn by several previous observers. A 

 good instance of the very considerable volatility of the metal is describ- 

 ed as having occurred in a Barometer at the meteorological observatory 

 at Buxar, where considerably more than half a gramme of the metal 

 had been actually distilled into the upper part of the Torricellian vacuum 

 of the Barometer. The fact that such a large quantity of mercury can 

 thus distil upwards is one of which meteorologists should take note, for 

 had the barometer in question been constructed on what is called the 

 Kew principle, which is the case with a very large proportion of the 

 barometers that are used, the distillation of this quantity of mercury 

 in the instrument would have utterly vitiated all its readings by causing 

 them to be distinctly lower than they should have been. 



Experiments as to the volatility of mercurial compounds were made 

 on the following substances : — Mercuric oxide, mercuric cyanide, mer- 

 curic oxalate, mercuric iodide, mercuric bromide mercurous chloride 

 (calomel) and mercuric chloride (corrosive sublimate). The experi- 

 ments were usually made in vacuo and in a part of the vacuous space, 

 containing the mercurial compound, some re-agent was placed which 

 had the power of combining with and fixing one of the constituents of 

 the subslance experimented on. The volatility was determined under 

 the conditions of an Indian climate (in Calcutta) generally at tempera- 

 tures obtained in full sunlight, but also in some cases at shade tempera- 



