D. CHEMISTRY AND METALLURGY. 183 



tact for an hour, and with a pressure varied between 20 and 

 40 atmospheres. Sulphur and phosphorus are insoluble in it, 

 while iodine dissolves sparingly, imparting a pale violet tint. 

 Water dissolves but little of it, the excess of the liquid acid 

 floating upon the solution. Petroleum dissolves five-sixths' vol- 

 umes of the liquid, the first portions producing a marked stri- 

 ated appearance, as seen in mixing liquids of different densi- 

 ties. With a small quantity of petroleum, saturation soon takes 

 place, and the excess of acid floats on the top, with the sur- 

 face of separation sharply defined. On diminishing the press- 

 ure, the carbonic acid becomes gaseous with violent rapidity ; 

 and it is only after it has all passed off, and the pressure has 

 been considerably diminished, that the petroleum gives up 

 the dissolved acid. Bisulphide of carbon mixes with it spar- 

 ingly. Sulphuric ether absorbs large quantities, perhaps in 

 all proportions. At 20 atmospheres, far below the point at 

 which liquefaction begins, the gas entirely disappears, and 

 during solution the striated appearance may be noticed. 

 Unctuous oils dissolve sparingly in it. Tallow, under these 

 circumstances, becomes white upon the surface, and loses its 

 oily portions. Stearin and paraftine are insoluble in it. , Soda- 

 amalgam had no reducing effect, and metallic sodium, after 

 contact of more than an hour, was simply coated with a film 

 of bicarbonate. The oxidation in the case was, however, due 

 to the presence of a small quantity of moisture, and not to 

 the decomposition of the carbonic acid. 19 C^ January 25, 

 1873,37. 



SOLIDinCATIOX OF NITROUS OXIDE. 



In a paper read by Mr. Wills before the Chemical Society 

 of London, an account is given of the process and apparatus 

 necessary to obtain nitrous oxide in a solid state by the 

 evaporation of the liquid. In this he states that, although 

 the apparatus which he described was generally the most 

 convenient, the liquid nitrous oxide will quickly become solid- 

 ified if a rapid current of air be passed through it. Unlike 

 carbonic acid, the liquefied gas can be readily preserved for 

 some length of time in an open vessel, provided it be kept 

 still. Liquid carbonic acid becomes solid as soon as it escapes 

 from the vessel containing it, since the vapor tension of the 

 carbonic snow at the time of its formation is much above the 



