Chemistry and Physics. 327 



evaporation the ozone became a bluish gas which readily recon- 

 densed in liquid ethylene. 



The author has succeeded in solidifying liquefied ethylene by 

 ^enclosing it in a tube surrounded by liquid oxygen, this tube 

 being itself surrounded with liquid ethylene. It was found to 

 solidify at about the boiling point of oxygen — 181-4°, to a white 

 crystalline semi-transparent mass. On allowing the pressure and 

 temperature to increase gradually by closing the stopcock which 

 allowed the oxygen to escape, the solid ethylene became liquid at 

 a pressure of 3*4 atmospheres, at which, as the author has shown, 

 the temperature of the liquid oxygen would be —169°. This may 

 therefore be taken as the melting point of solid ethylene. — Ann. 

 Phys. Chem., II, xxxvii, 337-340; J. Chem., Soc. lvi, 821, Sept., 



1889. G. E. B. 



4. On the Constitution of the Thionic acids. — Beethelot has 

 made a thermochemical study of the action of alkali hydrate upon 

 the thionic acids. Treated with excess of the hydrate the penta- 

 thionates evolve heat and give thiosulphate. Since the heat ob- 

 served was only -J-44 cal., while complete decomposition requires 

 +48 cal., the change is incomplete. If the change of penta- 

 thionic into thiosulphuric acid be effected by the assimilation of 

 water according to the reaction (H 2 S 5 O c ) 2 +(H 2 0) 3 =(H 2 S 2 3 ). 

 the heat absorbed would be —34-6 cal. But this conversion in- 

 creases the saturating power and corresponds to an increase of 

 the heat of neutralization of -f-82'8 C al.; leaving a balance of 

 + 48*2 cal. in favor of the reaction. When tetrathionates are 

 treated with alkali hydrate they are slowly converted into thiosul- 

 phate and sulphite (Bra 1 S 4 6 ),+ (Na 1 0) I =(Na 1 S 1 O i ), + (Na 1 SO,) t . 

 This reaction when complete gives rise to an evolution of heat 

 corresponding to +72*6 cal., and the conversion of tetrathionic 

 acid into thiosulphuric and sulphurous acids would absorb — 18 - 6 

 cal. The exothermic character of this reaction, like that of the 

 preceding one, depends on an increase in the saturating power of 

 the acids. The trithionates are more stable and their reaction 

 with alkali hydrate cannot be detected at ordinary temperatures 

 until after a considerable time. On heating, however, the trithi- 

 onate is converted into thiosulphate and sulphite (K 2 S 3 6 ) 2 + 

 (K 2 0) 3 =K 2 S 2 3 -+-(K 2 S0 3 ) 4 ; a change corresponding when com- 

 plete to the evolution of +35 '8 cal. The heat absorbed by the 

 conversion is —36*2 cal., but that corresponding to the increase 

 in the heat of neutralization is +72-0 cal. On the dithionates in 

 the cold, sodium hydrate has no action. From these results 

 Berthelot regards -the thionic acids as derivatives of condensed, 

 simple or mixed anhydrides, themselves derived from thiosul- 

 phuric and sulphurous acids. If thiosulphuric acid be regarded 

 as S 2 2 . H 2 0, it is capable of giving rise to a series of condensed 

 anhydrides having the general formula ??S 2 2 . n— mH 2 0, the 

 basicity of the resulting acids being proportional to m. Hence 

 according to this view pentathionic acid would be (S 2 2 ) 5 (H 2 0)„, 

 n and m being in this case 5 and 3 respectively. If sulphurous 



