1865.] Liquefied Hydrochloric Acid Gas. 211 



fectly soluble in water, but instantly soluble in dilute hydrochloric acid. 

 Binoxide of tin in powder did not dissolve in seven days ; the residue was 

 white and insoluble in water. A crystal of protochloride of tin softened 

 before the gas liquefied, and partly dissolved in the liquid acid in four days. 

 Bright metallic thallium evolved no gas in the liquid acid, and was only 

 superficially blackened without further corrosion after three days' immer- 

 sion. Metallic lead did not evolve visible gas in the liquefied acid ; it 

 became blackened at first, and in ten days was corroded deeply to a white 

 substance. Red oxide of lead quickly became white in the liquid acid, 

 but did not dissolve in seven days ; it was then quite hard, white through- 

 out, and not readily soluble in water. Precipitated carbonate of lead 

 evolved no visible gas in the liquid acid, and remained undissolved after three 

 days' immersion ; the residue evolved no gas by contact with dilute hydro- 

 chloric acid. Precipitated sulphide of lead in powder produced a faint 

 film of white sublimate in the gas, and by a few hours' immersion in the 

 liquid acid became wholly white ; it did not not dissolve during seven days, 

 and was then quite white throughout, and not readily soluble in water. 

 Yellow iodide of lead did not dissolve in seven days, but became of a pur- 

 plish brick-brown colour and evolved a strong odour of free iodine ; it 

 produced yellowish-brown stains upon paper. Yellow chromate of lead 

 evolved at first (in the gaseous acid) a small quantity of deep-red vapour, 

 which condensed as a red moisture near it on the tube ; the chromate 

 became white] in the gas, and did not dissolve in the liquid acid in three 

 days ; it was then a soft white solid, not freely soluble in water, and im- 

 parted a faint greenish tint to water. 



A minute fragment of iron remained bright, and evolved no gas when 

 the liquid acid came into contact with it ; after nine days of intermittent 

 immersion it was only slightly tarnished, and on removal from the acid 

 was found otherwise unaltered. A fragment of fused sulphide of iron pro- 

 duced a faint film of whitish sublimate at first, but evolved no bubbles of 

 gas on contact with the liquid acid ; it did not dissolve or alter in appear- 

 ance. A second fragment constantly immersed during three days behaved 

 similarly; it was as hard as before immersion, and evolved sulphuretted 

 hydrogen freely in hot dilute sulphuric acid. A crystal of green vitriol 

 became yellowish white and opaque in the liquid acid, but did not diminish 

 in volume in six days; the residue was a soft opaque yellowish- white solid. 

 Oxide of cobalt in powder exhibited no change or solution during three 

 days ; on removal it was found to be very hard, of a light-brown colour, 

 and dissolved in water, producing a pink solution with separation of black 

 oxide. Peach-coloured carbonate of cobalt evolved no visible gas in the 

 liquid acid ; it became greenish blue, but did not lessen in bulk in three 

 days ; the residue became pink in the air, and dissolved almost completely 

 in water, forming a pink liquid ; it also dissolved in dilute hydroclhoric acid 

 without evolving bubbles of gas. Anhydrous chloride of nickel did not dis- 

 solve in the liquid acid in six days. Metallic copper soon lost its brightness 



