Properties of Liquefied Hydrochloric Acid Gas. 545 



by immersion in the liqnid acid ; it remained undissolved and un- 

 changed in appearance during three days' immersion ; the residue 

 evolved a minute quantity of gas by contact with dilute hydrochloric 

 acid. Precipitated carbonate of strontia in powder behaved like 

 carbonate of baryta ; the residue, after three days' immersion, was 

 lost during the discharge. A minute fragment of anhydrous Bristol 

 lime exhibited no solution or alteration by nearly constant immer- 

 sion during eight days in the liquid acid. On removal from the 

 tube, it imparted a strong blue colour to neutral litmus paper by 

 slight friction. On fracture it was found similarly alkaline through- 

 out, and exhibited a slight change of colour, extending from its sur- 

 face to the centre, as if the gas or liquid had been forced into its 

 pores. In a second experiment of three days' intermittent immer- 

 sion, precisely similar effects were obtained. Several minute frag- 

 ments of very soft marble were immersed in the liquid acid at in- 

 tervals during seven days. No gas was evolved when the liquid 

 touched them. On removal from the acid, their physical characters 

 appeared unaltered ; they were insoluble in water, but quickly dis- 

 solved in dilute hydrochloric acid, with copious evolution of gas. A 

 fragment of bone-earth did not dissolve or alter in appearance during 

 seven days. 



Bright magnesium ribbon slowly became dull in the liquid acid, 

 without visible evolution of gas ; after seven days' intermittent im- 

 mersion it was still (with the exception of a thin film) in the metallic 

 state. In a second experiment of three days' constant immersion, 

 similar effects occurred ; the residue dissolved and floated in dilute 

 sulphuric acid, with copious evolution of gas. A wire of magnesium 

 and one of platinum immersed in the liquid acid, and connected 

 with a sensitive galvanometer, evolved no perceptible electric current, 

 and only a barely perceptible current after two days of constant im- 

 mersion. Calcined magnesia in powder did not dissolve or alter in 

 appearance during four days' nearly constant immersion. Oxide of 

 cerium (containing some oxide of didymium and lanthanum) re- 

 mained undissolved and unchanged in colour during nine days ; the 

 residue was insoluble in water. Metallic aluminium became dull in 

 the gas, and quickly dissolved, with evolution of gas, when the 

 liquid acid came into contact with it, and formed a colourless solu- 

 tion. A wire of aluminium and one of platinum, immersed ^-th of 

 an inch apart in the liquefied acid, and connected with a sensitive 

 galvanometer, produced a steady deflection of 12j degrees, the alu- 

 minium being positive ; the deflection gradually increased to 1 7 

 degrees in one hour, and two layers of liquid formed, the lower one 

 brown in colour, and the upper one nearly colourless. The conduc- 

 tivity of the liquid acid was probably increased by the metallic 

 aluminium dissolved in it. Precipitated alumina did not visibly 

 alter or dissolve during six days ; the residue deliquesced in damp 

 air. Precipitated silica in powder did not dissolve or visibly alter 

 during four days. Precipitated titanic acid in powder (pale flesh- 

 colour) slightly dissolved in seven days. 



A fragment of fused tungstate of soda did not alter in bulk during 



