25 
carbonate solution of known strength and with the addition 
of water. No soda was retained. 
(IY.) The above experiment was repeated with finely 
powdered marble, with like negative results. 
(Y.) A quantity of milk of lime was now taken, and 
boiled with 25 c.c. of the Na 2 C0 3 solution. After filtering, 
washed with 500 c.c. of hot water, removed lime, filtered, 
washed, evaporated to dryness, ignited, dissolved in water, 
and titrated, 1-286 per cent Na 2 0 was retained by the cal- 
cium residue. 
(VI.) A quantity of milk of lime taken, and to it were 
added 25 c.c. of caustic soda solution with some water. 
The whole was boiled for sometime — 0-05 per cent Na 2 0 re- 
tained. Some of the sodium hydrade becoming accidentally 
carbonated might account for this. 
This lime mud residue of (V), washed as above till the 
filtrate ceased completely to react alkaline, was washed into 
a flask and a current of C0 2 was passed through for a long 
time, to endeavour to decompose this insoluble compound. 
In this way only 0-078 per cent of the soda (Na 2 0) was 
extracted. 
We now attempted to prepare some of the double sodium 
calcium carbonate in the following manner : — 
A quantity of pure sodium carbonate solution (somewhat 
concentrated) was mixed with about three times its volume 
of clear lime water, and this mixture was heated to boiling. 
The precipitate was allowed to settle, was filtered, and 
washed with hot water till the filtrate ceased to manifest 
the slightest alkalinity to test paper. It was then dried in 
the water bath. When the lime water was added to the 
sodium carbonate solution, the precipitate of carbonate 
which came down had the floccular appearance of alumina 
