1824.] Liquefaction of Chlorine and other Gases. 97 



be. In the course of some days, action had taken place, the 

 water had become black, and changes, probably such as are 

 known to take place in an aqueous solution of cyanogen, 

 occurred. The pressure of the vapour of cyanogen appeared by 

 the gage to be 3-6 or 3*7 atmospheres at 45°. Its specific 

 gravity was nearly 0*9. 



Ammonia. 



In searching after liquid ammonia, it became necessary, 

 though difficult, to find some dry source of that substance; and 

 I at last resorted to a compound of it, which I had occasion to 

 notice some years since with chloride of silver.* When dry 

 chloride of silver is put into ammoniacal gas, as dry as it can be 

 made, it absorbs a large quantity of it : 100 grains condensing 

 above 130 cubical inches of the gas ; but the compound thus 

 formed is decomposed by a temperature of 100° F. or upwards. 

 A portion of this compound was sealed up in a bent tube and 

 heated in one leg, while the other was cooled by ice or water. 

 The compound thus heated under pressure fused at a compara- 

 tively low temperature, and boiled up, giving off ammoniacal gas, 

 which condensed at the opposite end into a liquid. 



Liquid ammonia thus obtained was colourless, transparent, 

 and very fluid. Its refractive power surpassed that of any other 

 of the fluids described, and that also of water itself. From the 

 way in which it was obtained, it was evidently as free from water 

 as ammonia in any state could be. When the chloride of silver 

 is allowed to cool, the ammonia immediately returns to it, com- 

 bining with it, and producing the original compound. During 

 this action a curious combination of effects takes place : as the 

 chloride absorbs the ammonia, heat is produced, the tempera- 

 ture rising up nearly to 100° ; while a few inches off, at the 

 opposite end of the tube, considerable cold is produced by the 

 evaporation of the fluid. When the whole is retained at the 

 temperature of 60°, the ammonia boils till it is dissipated and 

 re-combined. The pressure of the vapour of ammonia is equal 

 to about 6*5 atmospheres at 50°. Its specific gravity was 0*76. 



Attempts have been made to obtain hydrogen, oxygen, 

 fluoboracic, fluosilicic, and phosphu retted hydrogen gases 

 in the liquid state ; but though all of them have been sub- 

 jected to great pressure, they have as yet resisted conden- 

 sation. 



Article III. 



New Locality of the Skorodite. By W. Phillips, FLS. MGS.&c. 



Tut: crystals forming the subject of this notice were lately 

 received in a letter addressed to me from " Calenick, near 

 Truro," and signed "J. Michell," us having been "obtained 



• Quarterly Journal of Science, vol. v.\>- 71. 



New Series, vol. vii. h 



