52 T. S. Hunt on Lime and ‘Magnesia Salts. 
_ at 0°C., and that it is capable of being used with still greater 
advantage than a stronger acid for the investigation of these 
mixtures of carbonates. In some further experiments to be de- 
tailed below, the action of an acid thus diluted upon an excess 
of the mixed anonaes = made available for a process of 
fractional separation (§ 10 
§ 79. In §$ 30 the Aeneas of Bischof, showing the sparing | 
solubility of dolomite in carbonic-acid water, were cited, and in 
farther illustration the following observation, since made, may 
recorde One gram of a very pure crystalline dolomite 
in he i fine powder was suspended in little. more than half 
a liter of water, which was then saturated with carbonic acid at 
the ordinary pressure, and the mixture digested for eighteen 
hours at about 18° C. with frequent agitation. At the end of 
this time the water held in solution an amount equal to 0:15 gr. 
to the litre of the two carbonates, in the proportion of carbonate 
of lime 57, carbonate of magnesia 43. In order to determine 
carbonate dissolved was oo to 0°39 grs. to the liter. In order { 
to show the relative solubilities in carbonic-acid water, of dolo- | 
mite in fine powder and pure precipitated carbonate of lime, a | 
mixture of one gram of each was digested for eighteen hours | 
with half a liter under the conditions — described, when there 
were found in solution carbonate of lime 0-380 and carbonate of 
magnesia 0:007, equal to 0-015 of dolomite, so that only about 
four parts of the latter were dissolved for ninety. six of carbon- 
ate of lime. 
80. The next point of interest in my previous paper 
an inquiry into the a mata in which the double naboiaiie ; 
of lime and magnesia, known as dolomite, may be peo 
Starting from the well ene fact that gypsums are generally 
associated with dolomite, (although great deposits of dolomite 
are often without gypsum), and from the unfounded notion that 
oe dolomites are formed by a process of alteration from pre- 
viously de the ea limestones, Haidinger had suggested that the 
e carbonate of magnesia might be due toa reaction, 
