i 157 ] 

 XXIII. Intelligence and Miscellaneous Articles. 



ON THE LIMIT OF VAPORIZATION OF MERCURY. BY C. BRAME. 



TJ^ROM the numerous experiments which I have made on this subject, 

 •*■ it appears, — 1 , that gold, which was employed for the purpose by 

 Mr. Faraday, is not a sufficiently sensitive reagent for the detection of 

 very small quantities of the vapour of mercury ; and that if, as Faraday 

 has done, we are able by this means to prove that at 68° to 77° F. mer- 

 cury gives off vapour to a height of more than m- 100, and if the for- 

 mation of this vapour can nolonger be shown at more thanO m- 020 when 

 the temperature is below 32° F., this does not prove that mercury has a 

 limited atmosphere. 2. On the contrary, it is proved that the vapour 

 of mercury rises easily to 1 metre at temperatures comprised between 

 a few degrees below 32° F and 86° F. Moreover, it has been ascer- 

 tained in M. Chevreul's laboratory, that when a tube of a diameter 

 of m- 050, open at both ends, was placed over mercury at a tem- 

 perature of 68° to 78° F. for a fortnight, the vapour of the latter 

 gave a brown colour to vesicles of sulphur placed at a distance of 

 l m '440 from the surface of the mercury. In the vaults of the obser- 

 vatory, vesicles of sulphur placed at a distance of l m- 760 from the 

 mercury were rendered entirely brown in four months ; the sulphur 

 was placed in a small tube open at both ends, and supported by a 

 spiral iron wire in a larger tube closed at one end, and reversed over 

 the mercury. The larger tube was m- 021 in diameter, and l m, 80 

 in height. In twenty days, in the same situation, the vapour of 30 

 grms. of mercury, placed at the bottom of tubes from l ni- 100 to 

 l m, 200 in height, gave a brown colour to vesicles of sulphur depo- 

 sited on the sides of little flasks which served <xb stoppers. The same 

 result was obtained several times, the temperature sometimes remain- 

 ing constant, as in the vaults of the observatory, sometimes varying 

 18° F. or more, as in the laboratory, &c. ; the air in the tubes 

 was sometimes more or less free, sometimes confined, without the 

 appearance of any sensible difference. At all temperatures it is 

 always sulphuret of mercury that is formed ; at 32° F. and above that 

 temperature it is of a deeper or paler brown, but at 18°F. the vapour of 

 mercury gave a yellow or red colour to vesicles of sulphur placed at a 

 distance of several centimetres; the vapour of soft amalgams had often 

 the same effect. In the former case, by continuing the experiments for 

 a sufficiently long time, ponderable quantities (0'006 to 0'0230 gr.) 

 of mercury were condensed in the vesicles of sulphur, and the same 

 was the case with mercurial ointment, amalgams of silver, tin, &c. 

 Vesicular sulphur, the needles produced by fusion and hardened sul- 

 phur, which contain vesicles, take up mercury, even when placed at 

 the bottom of tubes of half a metre in length resting upon mercury. 

 3. When, under the circumstances already indicated, vapour of 

 iodine (produced in very small quantity at the ordinary temperature by 

 a few centigrammes of iodine volatilized and condensed on the walls 

 of a small flask serving as a stopper for the tube) descending from 

 the upper part of the tube containing the mercury was substituted 

 for the vesicular sulphur, the vapour of mercury appeared to form a 

 limited atmosphere above the liquid metal. In fact, iu this case, it 



