58 Frederick Guthrie on Salt Solutions 



were treated in the same way. This gave solution (2). On 

 cooling (1) and (2), they showed the same behaviour throughout 

 and solidified to dryness at —5°. And accordingly there is 

 so far nothing in their behaviour to disprove their identity. 

 But this does not show that partial double decomposition has 

 ensued in both cases to produce in each mixture a portion of 

 the original synthetical constituents of the other. On the con- 

 trary, a comparison of this experiment with those above dis- 

 cussed (of the form AX + BX) goes very far to prove, not that 

 there are four salts in each of the solutions 1 and 2, but that 

 there is none of the original salts in either. For it has ap- 

 peared that when AX and BX are mixed in solution, the tem- 

 perature of final solidification is in no case sensibly above the 

 temperature required for the solidification of that constituent 

 whose solidification takes place at the lowest temperature. 

 Now, if in solution (1) or (2) there were nitrate of sodium pre- 

 sent, whether original or derived, the final solidification would 

 not take place above —17° instead of —5° as found. The 

 absence of nitrate of sodium argues forcibly for the absence of 

 each of the other single salts. The most rational formula for 

 such a mixture is the most empirical one possible. As we 

 cannot intertwine the symbols into a monogram in three dimen- 

 sions, I arrange them alphabetically, and denote either of the 

 solutions 1 or 2 by B^KNaNaOn+ioS. I suppose the time 

 will come when it will be held as illogical to consider that 

 KN0 3 exists in a solution of nitre as it would be to regard a 

 circle as a straight line which has been bent round. 



§ 119. The same salts as in § 118 were now taken, but not 

 in equivalent quantity ; namely 



grnis. grins. 



For solution A there were 66 of Na 2 S0 4 and 87*72 of KX0 3 , 

 B „ 91 „ K 2 S0 4 „ 85 „ NaX0 3 . 



The salts, as before, were mixed, dissolved, evaporated to 

 saturation, and cooled. The solutions being saturated at + 12°, 

 were first cooled in ice for an hour. During this, two kinds 

 of crystals separated from each in sensible quantity. On further 

 cooling, the temperature became and remained constant at 

 — 5° up to solidification. The last liquid portions of A and B 

 having been removed to separate vessels before final solidifica- 

 tion, were examined as far as their proportion of sulphuric acid 

 is concerned. 



The mother-liquor of A showed in 



2-277 grms. 

 •4205 grm. of ignited residue, 



