22 
of limestone was used. Wright examined the resulting pro- 
duct to see if more of this insoluble compound were formed, 
and found there was. 
Mactear (Chem. News, Feb. 2, 1872, p. 55) makes the 
interesting discovery that “ oxidised alkali waste yields on 
lixiviation almost all the soda contained in the waste.” The 
soda thus rendered soluble occurs in the solution as sulphate. 
Mactear says “The chief loss in the soda process is that 
which occurs during lixiviation of the ball soda. This loss 
is in part represented by the insoluble and soluble compounds 
left in the waste. The former sometimes amounts to 3 or 4 
per cent of the soda, and the amount is increased as the 
silica and alumina of the raw materials increase.” 
Wright has shown that an increase of limestone in the 
black ash mixture will also increase the amount of the 
insoluble soda compound. 
Scheurer-Kestner (Comptes Rendus, Nov. 11, 1872) con- 
firms Wright’s views. He proves conclusively that an 
increase of chalk in the black ash mixture causes a propor- 
tionate increase in the amount of insoluble soda compounds 
left in the waste. “ The excess of chalk employed is con- 
verted into lime, and when the crude soda is lixiviated with 
water, the lime while becoming hydrated reacts upon the 
sodium carbonate and thereby renders a portion insoluble 
in water.” According to Seheurer-Kestner’s experiments, 
the lime may retain even as much as from 475 to 4*95 per 
cent of soda Na 2 0. 
With regard to our own experiments, we first operated 
upon some samples of soda waste, with the view of deter- 
mining the soluble and insoluble soda therein contained. 
After titration and digestion with water of about 60°, 
for an hour, a sample of waste yielded us 0*22 per cent of 
alkali as Na 2 0 soluble in water. On solution of the residue 
in acid, a gravimetric determination of the residual and 
