Magnesian Limestone . 
319 
His experiments were made, evidently on secondary limestones 
containing magnesia ; and the stratum of this kind of limestone he 
found superincumbent on the purer calcareous stone ; and which 
in general he considers as alluvial limestone, in reference to the 
strata on which his experiments were made. 
Judge Peters transmitted to me, nine different specimens of 
limestone from Chester county, numbered and named as follows : 
No. 1 Holstein. , No. 5 Hughes’s. 
2 Coates’s. 6 Dr. Gardener’s 
3 Yocum. 7 Barnet’s, 
4 Cleaver’s. 8 Bailee’s. 
9 Baker’s. 
Of these No. 7 is regarded as the strongest for building or for 
land, and No. 9 the weakest. The first four are strong lime, 5 
and 6 of medium quality, and No. 8 nearly equal to No. 7 : that 
is, according to their reputation in the neighbourhood. 
Upon these limestones I have made experiments for the purpose 
of ascertaining their component parts, but chiefly as to the magne- 
sian earth, they may hold. 
It is not an easy problem to discover the most simple, the cheap- 
est, and the most accurate method of separating magnesia from 
limestone and clay, (from lime and alumina.) 
We have no good precipitant of magnesia : phosphoric acid re- 
quires combinations that make the results complicated, and drive 
us to calculation, which when I can, I would avoid. 
The following methods have been used, to separate magnesia 
from a combined solution of lime and magnesia in the muriatic 
acid. 
1st. Separate the lime by the oxalic acid. This is too expen- 
sive. 
2ly. Precipitate the lime by saturated carbonat of potash, which 
in the cold throws down the carbonat of lime, and the residual 
liquor heated lets fall the carbonat of magnesia. This is a me- 
thod recommended by Davy and Henry ; but I have never been 
able by this method perfectly to keep separate the carbonats of 
these two earths. 
Sly. Throw down the carbonat of lime by carbonat of ammonia: 
filter : then add to the muriat of magnesia containing carbonat of 
ammonia, pliosphat of soda. The ammoniaco-phosphat of mag- 
nesia is precipitated ; and 151 grains of this triple suit dried at 
90° of Fahrenheit, answers to 100 grains of muriat of magnesia. 
Hence, if 20 grains of a mixed solution of the muriats of lime and 
