66 T. S. Hunt on Lime and Magnesia Salis. 
in the previous two sections mi ¥ wre recorded in § 80, to see 
that in the present case a double anflydrous carbonate is actually 
a While in the ans ae preparations with sulphate of 
magnesia and carbonate of lime, or with the more hydrated 
residue is, by the farther action of the dilute acetic acid, shown 
a mixture of dolomite with magnesite. 
§ 108. But the most favorable conditions for the artificial sok 
duction of dolomite, so far as yet observed, are attained with a 
intimate mixture of the two carbonates in the amorphous ca 
as precipitated by a slight excess of carbonate of soda from the 
tion of equivalent ti of the chlorids of calcium 
and magnesium. (§ 82) o effect the union of the two car- 
bonates the heat should be very gradually raised to 120°-130°, 
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ordinary temperature, and a ain moistened with water and | 
acid with similar results to the preceding. e last residue of 
_ twenty-one per cent consisted of carbonate of lime 52° 7, carbon- 
ate of magnesia 47° 
It is unnecessary to multiply the descriptions of results of 
this kind obtained from five or six different preparations, and | 
all showing that under the influence of heat the pasty mix-  — 
ture of the two carbonates yields an anhydrous, sparingly | 
soluble compound having the chemical character and compost- | 
tion of dolomite, Poet requires carbonate of lime 54-35, carbon- 
ate of magnesia 
§ 109. In walang experiment a mixture containing more , than 
an equivalent of magnesian carbonate was heated as above 
described, and the portion dissolved by the first action of the 
acid contained 48°6 per cent of carbonate of magnesia, while 
the second portion dissolved had only 47-0 per cent, and the 
residue was pure magnesite. The excess of magnesia in the 
first fraction over the second would seem to be shor as in § 105, 
to a partial decomposition of the excess of hydrated magne- 
sian carbonate in the mixture. 
