1844.] of Bodies generally existing as Gases. 105 



long to apply the joint process of condensation already de- 

 scribed. The substance liquefied under a pressure of about 

 nine atmospheres at the lowest temperature, or at 160 below 

 0; and was then clear, transparent, colourless, and very fluid, 

 like hot ether. It did not solidify at any temperature to which 

 I could submit it. I was able to preserve it in the tube until 

 the next day. Some leakage had then taken place (for it 

 ultimately acted on the lubricating fat of the stopcock), and 

 there was no liquid in the tube at common temperatures ; but 

 when the bend of the tube was cooled to 32 by a little ice, 

 fluid appeared : a bath of ice and salt caused a still more 

 abundant condensation. The pressure appeared then to be 

 above thirty atmospheres, but the motion of the mercury in the 

 gauge had become obstructed through the action of the fluo- 

 silicon, and no confidence could be reposed in its indications. 



Phosphuretted Hydrogen. This gas was prepared by boil- 

 ing phosphorus in a strong pure solution of caustic potassa, 

 and the gas was preserved over water in a dark room for seve- 

 ral days to cause the deposition of any mere vapour of phos- 

 phorus which it might contain. It was then subjected to high 

 pressure in a tube cooled by a carbonic acid bath, which had 

 itself been cooled under the receiver of the air-pump. The 

 gas in its way to the pumps passed through a long spiral of 

 thin narrow glass tube immersed in a mixture of ice and salt at 

 0, to remove as much water from it as possible. 



By these means the phosphuretted hydrogen was liquefied ; 

 for a pure, clear, colourless, transparent and very limpid fluid 

 appeared, which could not be solidified by any temperature 

 applied, and which, when the pressure was taken off, imme- 

 diately rose again in the form of gas. Still the whole of the 

 gas was not condensable into this fluid. By working the 

 pumps the pressure would rise up to twenty-five atmospheres 

 at this very low temperature, and yet at the pressure of two or 

 three atmospheres and the same temperature, liquid would 

 remain. There can be no doubt that phosphuretted hydrogen 

 condensed ; but neither can there be a doubt that some other 

 gas, not so condensable, was also present, which perhaps may 

 be either another phosphuretted hydrogen or hydrogen itself. 



Fluoboron. This substance was prepared from fluor spar, 

 fused boracic acid and strong sulphuric acid, in a tube-gene- 



