OE Ps ere a OR ny See ee ee eC Cw ERNE eR ome Ren he pee RE Oe yr eR aa ay ap nee APE OTR NP merarena Aye TEE RNS yh ee 
T.S. Hunt on Lime and Magnesia Salis. 55 
found that when freed by washing from all trace of chlorids it 
yielded a quantity of soda equal to 1:86 per cent of carbonate 
of soda, and moreover that there was a deficiency in the amount 
of carbonic acid, which was only about nine-tenths of that re- 
quired to form neutral carbonates with the bases; so that the 
compound isa slightly basic carbonate of lime and magnesia 
with a little soda, “and with about ten per cent of water. 
ther analyses are required of this substance, which appears to be 
nearly related to the native hydrodolomite or dolomite-sinter of 
Kobell. 
e magma obtained as in the last section slowly 
§84. Th 
changes at ordinary temperatures into a crystalline compound 
ri 
much more hi ghly hydrated than the last. tall cylindrical 
jar filled with the paste of the freshly Eeepiptipe’, carbonates 
and exposed to the light at a temperature of 15° to 18° C., after 
twenty-four hours showed a layer of liquid at the surface from 
a partial subsiding of the precipitate, which, at the end of 
twelve days in one case, and twenty-five in another, pa 
only one-seventh of the original volume. The process ‘of change 
appeared to consist in the formation of nuclei, from which crys- 
tallization proceeded until every particle of the once volumin- 
ous, opaque and amorphous precipitate had become translucent, 
dense and crystalline. The phi ak liquid was alkaline 
from an excess of carbonate of soda, and held only traces of 
carbonate of magnesia in solution. The precipitate washed by 
decantation and dried on blotting paper, consisted of brilliant 
ecome opaque on the edges, without, however, losing their 
hardness, Leated in a glass tube they give off much water with 
decrepitation. The following are the results of two analyses of 
portions of this carbonate from the same preparation, but dried 
at different times by exposure to the air for several hours at 
18°C. The carbonates were supposed to be neutral 
though no determination of the carbonic acid was 7 e. The 
carbonate of soda was separately determined on five grams, 
the absence of chlorids having been established, a Ae water 
estimated from the loss: 
I. 
Carbonate of i - - 87-74 8608 
pik de - - 31°38 31°06 
oda, us 2°18 2-18 
Watdh by siecle 7 - 28°70 29°78 
