61 
tals he obtained by the action of a boiling solution of sodium 
carbonate upon a smaller quantity of a solution of calcium 
chloride of 1*13 spec, gr., and letting the whole stand for 
some days. The analyses of these crystals showed them to 
consist, as Gay-Lussite does, of CaC0 3 , Na 2 C0 3 -f5H 2 0. On 
heating with water the body is decomposed, sodium carbon- 
ate being dissolved and calcium carbonate being left behind. 
It was also found that the salt, when dehydrated, is more 
easily and quickly decomposed by water than before dehy- 
dration, and it would appear in fact as if the calcium car- 
bonate and sodium carbonate were simply held together by 
the water of crystallisation. 
When Fritzsche came to analyse the crystalline body he 
obtained, he attempted it by washing out the sodium carbon- 
ate, igniting the residue of calcium carbonate, and weighing 
the calcium oxide remaining after the ignition. On testing 
the residue by solution in very little hydrochloric acid, a very 
small evolution of carbon dioxide was observed, and this led 
to further examination, resulting in the discovery of a small 
quantity of sodium carbonate which had remained insoluble 
with the calcium carbonate. Fritzsche promised to experi- 
ment further in this new direction, but it does not appear 
that he has. Nevertheless, the results he obtained show 
that in two experiments the quantities of sodium carbonate 
retained as insoluble in the calcium carbonate residue, after 
careful washing, were, (1st) 1*8 per cent, (2nd) 2 ‘4 per cent, 
thus closely agreeing with the amounts we found in our 
crystalline precipitates, the analyses of which are given 
above. 
Of course we are aware that several speculations might 
be advanced to account for the occurrence of the soda in the 
calcium carbonate in the insoluble form, but it seems to us 
most in accordance with the results we have obtained, with 
others, to view it as combined with an equivalent propor- 
tion of calcium carbonate, an insoluble compound being 
formed. 
