Iron alum, magnetization

Iron ammonium alum, Fe2(S04)3 (NH4)2S04 24H20, has a Curie constant of 4.35 cm3 deg/mol and a molecular weight of 482. The specific heat constant Aj/R is 0.0142 deg2. Its density is 1.71 g/cm3. The material is placed in a magnetic field of 10,000 G, cooled to 1.5 K, and subsequently demagnetized adiabatically. What is the final temperature attained with this material ... 

Iron and Sulphur—Subsulphides of Iron—Ferrous Sulphide—Ferric Sulphide-Double Sulphides—Iron Pyrites—Marcasite—Magnetic Pyrites—Ferrous Sulphite—Ferri-sulphites—Ferrous Sulphate—Double Sulphates—Fern-sulphates—Alums—Anndo-sulphonates, Thiosulphate, Disulphate, and Thionates of Iron. 

The nitrate, Fe(N03)3.9H20, gives a broad resonance at 1-8 K due to relaxation [98]. The application at room temperature of an external magnetic field of up to 5 kG produces a central narrow component on a broad background similar to that observed with iron(III) alum, but the detailed relaxation processes have not been studied [118]. 

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