59 
strongly for about an hour, subsequently treated with 
dilute spirits of wine (water and alcohol, 5:2) filtered, 
washed well, any little lime in the filtrate precipitated, 
again filtered, washed, and the filtrate finally evaporated 
to dryness and weighed. Thus it was found that every 
trace of soda was extracted from the substance, both by ex- 
amining the perfectly white sodium carbonate obtained, 
qualitatively, and also the residue of calcium carbonate 
with the spectroscope. The weight of Na 2 C0 3 extracted 
was found to be 2*00%, closely agreeing with the amounts 
determined. (See above analyses A and B.) 
(2) A weighed quantity of the crystalline precipitate was 
now subjected to a six-hours’ continuous boiling with water, 
adding water from time to time to replace that evaporated. 
By this means 17% Na 2 C0 3 was extracted, leaving about 
Q‘2% Na 2 C0 3 in the residue, which the six-hours’ boiling 
therefore failed to remove. The residue on spectroscopic 
examination showed that soda still remained behind. 
Doubtless another hour’s boiling would entirely remove it. 
(3) The effect of boiling for six hours with a solution of 
sodium sulphide, obtained by lixiviating the mass resulting 
after fusing a mixture of ordinary salt-cake and charcoal, 
showed us that by this means much less soda is extracted 
than when pure water is used. The six-hours’ boiling ex- 
tracted only 0‘5% Na 2 C0 3 , thus leaving about 1*4% in- 
soluble in the residue. The crystalline precipitates we 
obtained as described were anhydrous as the analyses show. 
With regard to the lime-mud , the soda insoluble in water, 
and which long washing with hot water could not remove, 
was found in another sample of the mud to be 2*10% 
Na 2 C0 3 , the amount of soluble alkali =2*62%, giving a total 
content of soda as 
2T0% Na 2 C0 3 insoluble 
2-62% „ soluble 
472% 
total. 
