SEPARATION OF POTASSA AND SODA 237 
43.5 grains of sulphate of baryta contain 15 of sulphuric 
acid. The united weights of the alkalies is therefore 14; | th 
of which is 2|. The oxygen of the baryta, in 43.5 grains of 
the sulphate of baryta, is 3 grains. Taking 2§ from three, we 
have fds, which multiplied by 12 gives 8 grains for the 
weight of the soda. This taken from 14 leaves 6 grains for 
the weight of the potassa in the mixture. 
At the suggestion of my friend, Professor H. D. Rogers, I 
am induced to extend the foregoing method of calculation to 
the usual way of determining the quantities of the alkalies by 
their conversion into the chlorides of their metallic bases, 
avoiding the ordinary step which requires their separation by 
the use of chloride of platinum, by determining the chlorine 
in the mixture, by nitrate of silver. 
(A) The alkalies are to be converted into muriates, if not 
already in that state, by the ordinary steps of mineral analysis. 
These being evaporated to dryness, ignited and weighed, will 
give the amount of chlorides of potassium and sodium which 
are present. 
(B) Dissolve the mixed chlorides in water acidulated with 
nitric acid. Nitrate of silver will throw down the chlorine, 
and by treating the precipitated chloride of silver in the usual 
way, the quantity of chlorine is deduced from the weight of 
the fused chloride. 
To calculate the weights of the alkalies; let v and z repre- 
sent the weights of the potassa and soda respectively; c the 
weight of the mixed chlorides (A,) and d that of the chloride 
of silver (B.) Using 146 as the equivalent of chloride of sil- 
ver, d grains of the chloride contain If d grains of chlorine; 
the weight of the metals in the mixed chlorides (A) is there- 
fore c — if d. But v grains of potassa contain J- v of potas- 
sium, and z grains of soda, I z of sodium. Whence £ v + f z 
The oxygen contained in the mixed alkalies is -jVths, or 
f-ths of the chlorine in the chlorides of their metallic bases, or 
is f-ths of if d, or -~ d. And as v grains of potassa contain 
J v grains of oxygen, and z grains of soda, i z grains of oxy- 
