27 
such a double carbonate were present in the crystalline pre- 
cipitated powders we obtained as already described. We 
reasoned thus : “ If such a double compound exist here, 
strong ignition ought to decompose it, driving off carbon 
dioxide from the lime, but leaving sodium carbonate intact,” 
thus 
.C0 2 0Na 
Ca = CaO + Na 2 C0 3 + C0 2 
^C0 2 0Na 
This experiment was tried with a small quantity of the 
crystalline precipitate. It was well ignited in a platinum 
crucible, and the resulting mass was treated with some 
dilute alcohol, which extracted easily a quantity of the soda, 
showing a strongly alkaline reaction to test paper. We 
intend to repeat this experiment quantitatively, and to deter- 
mine thus the amount of soda extracted. 
One point becomes pretty clear by these experiments, viz. 
that the materials lime and sodium carbonate in contact 
with water give rise to the formation of this insoluble sodium 
compound. Also that it is not a case of mere cohesive reten- 
tion of soda by the lime mud, for our experiments 
show that until a definite and suitable chemical reaction 
between the members of the mixture sets in, no appre- 
ciable amount of soda is retained, but that when such reac- 
tion sets in, in the condition of nascent state and therefore 
unstable equilibrium, in which the various constituents 
momentarily find themselves, a major and normal reaction 
takes place, and also this minor reaction to a small extent — 
giving us a small yield of the insoluble sodium compound. 
The experiments we have yet in view with the crystalline 
precipitate prepared as mentioned, and also with ordinary 
lime mud* are (1) the effect of long boiling with water to 
see if thus the insoluble compound is decomposed, as with 
