1873.] On the Union of Ammonia Nitrate with Ammonia. 109 



III. " On the Union of Ammonia Nitrate with Ammonia." By 

 Edward Divers, M.D. Communicated by Professor Odling, 

 M.B., F.R.S. Received October 29, 1872. 



(Abstract.) 



Ammonia nitrate deliquesces in ammonia gas at ordinary temperatures 

 and pressures, formiug a solution of the salt in liquefied ammonia. To 

 prepare the product, it is only requisite to pass dry ammonia gas into a 

 flask containing the dry nitrate; but the condensation proceeds more 

 rapidly if the flask is surrounded with ice. 



The liquid obtained varies in composition according to the temperature 

 and pressure. At a temperature of 23° and the pressure of the atmo- 

 sphere, it consists of about four parts of nitrate to one of ammonia by 

 weight ; but under greater pressure, or at lower temperatures, much more 

 ammonia can be condensed by the nitrate. At 0° and the pressure of 

 the atmosphere, two parts of nitrate can condense one part of ammonia. 

 Like an aqueous solution, the liquid boils when heated, and, when 

 nearly saturated with the nitrate, deposits crystals of it when cooled. It 

 can also, like an aqueous solution, be heated above its boiling-point 

 without boiling, and become supersaturated with the salt without crys- 

 tallizing. When poured out into an open vessel, it becomes almost 

 instantly gelatinous in appearance — may, indeed, become so as it falls in 

 a stream from the flask containing it. This effect is due to evaporation 

 of ammonia and solidification of nitrate at the surface of the liquid : on 

 breaking the crust of nitrate, the compound flows out as liquid as ever. 

 It is not caustic to the dry skin. During its decomposition cold is 

 manifested, and during its formation heat is evolved, but not to a great 

 extent, because the heat given out by the liquefaction of the ammonia is 

 nearly all used up in the liquefaction of the nitrate. 



The specific gravity of the liquid varies, of course, with its composition. 

 When it consists of two of nitrate to one of ammonia, it has a specific 

 gravity of 1072-5 ; when it consists of four of nitrate to one of ammonia, 

 it has a specific gravity of nearly 1200. Its specific gravity can 

 be calculated from its composition, by taking for the purpose 1524-5 as 

 the specific gravity of the nitrate, and 671 as that of the ammonia. The 

 number 1524*5 is much less than that expressing the actual density of 

 the nitrate in the solid state, but it does not differ very much fiom its 

 apparent specific gravity in aqueous solution. 



In its rate of expansion by heat, the liquid resembles others that exist 

 as such at ordinary temperatures, rather than those that, like ammonia 

 itself, are only retained as such by great pressure. Its expansivity 

 increases with the quantity of ammonia present. 



The volume of a mixture of the liquid with water is much less than the 

 sum of the volumes of the liquid and the water, and yet a marked 



