302 Dr. G. Gore on the Molecular 



Behaviour of a Solution of Sodium Sulphate. 



Experiment 18. — Dry crystals of the hydrated salt were dis- 

 solved in cold water, and the voltaic energy of the solution 

 measured ; it was 



Between 1,414 and 2,126 at 9° C. Average 2019 (see 

 also Table II.). 



The solution was now heated to about 100° C. in a closed 

 glass flask during two minutes and cooled ; its amount of 

 energy now was 



Between 1,839 and 2,039 at 9° C. Average 1939. 



And after boiling the solution to dryness and redissolving 

 the salt, the average amount of energy at 9° C. was still 

 = 1,939. 



General Conclusions and Remarks. 



It is evident from the results obtained that the chemical 

 and molecular constitution of the liquid " A," and the distri- 

 bution of acids and base in it, are affected by several circum- 

 stances : 1st By the degree of dilution of the ingredients at 

 the moment of mixing. 2nd. The temperature of the in- 

 gredients at that moment, or to which the mixture has after- 

 wards been subjected. 3rd. The order in which the ingredients 

 have been added to each other. 4th. The amount of light to 

 which the liquid has been exposed. And, 5th, the period of 

 time which has elapsed since it was made. In addition to this, 

 the liquid " A," even under the circumstances most un- 

 favourable to chemical change, suffers a great and variable 

 amount of such change during the mixing of its ingredients. 



With regard to the mixture " B/' it is well-known that it 

 suffers chemical change, attended by liberation of nitric acid, 

 during the mixing of its constituents. Thermochemical 

 researches have disclosed that it forms a compound, in which 

 one third of the soda is united to the sulphuric and two 

 thirds to the nitric acid, leaving two thirds of the former 

 acid and one third of the latter in a comparatively free state. 

 The present research proves that its ingredients, at the 

 moment of mixing, at once form a comparatively fixed sub- 

 stance or mixture, unalterable by various circumstances which 

 greatly affect the mixture " A ; " it also shows that the ex- 

 pelled portion of nitric acid probably unites chemically with 

 an equivalent portion or one half of the free sulphuric acid ; 

 and it further proves that under certain circumstances the 



