lf ~ i 68 Circulwr N0. 9. » , ` _ A
,' _. the limestone contains much magnesium carbonate. A lime-  
` . stone containing as much as 25% of magnesium carbonate J
A y c Y or more will require a notably longer time in dissolving in ,{
v l acid than a limestone containing only a small amount of mag- .
.i, . nesium carbonate. The highly magnesian limestones have a ,
A . very characteristic, vitreous, crystalline structure that is i
` unmistakable on a fresh fractured surface. This class of i
rocks is designated as dolomitic limestone and may contain  
_ as much as 40 per cent of magnesium carbonate and ,
. · sometimes a very small amount of insoluble matter. Most l
` ’ i · highly magnesian limestones are either lightgray or brown- I
» ish gray in color and have a very hard and flint-like fracture.
`V A one-gram portion- of a limestone containing a large .
amount of magnesium carbonate and a small insoluble residue _
' , will, when analyzed by the foregoing method, displace water
_ above the 100 percent mark, butcless than 105 percent mark.
_ A Hence a one—gram portion of any limestone displacing water
, c above the 100 per cent mark indicates that the stone is .
.' highly magnesian. ‘ I p i
_ , All readings above or below the 100 per cent mark are in l  
c terms of calcium carbonate (or pure limestone). ·
A 4 A complete apparatus as described in this circular can be  
c purchased from Messrs. Eimer & Amend of New York City  
for about $7.50. Any county agent desiring further inform- §
  ation in regard to either purchasing or manipulating the  
apparatus will addressothe Kentucky Agricultural Experi-  
ment Station, Lexington, Ky., and information will be  
` gladly furnished; V 0 _ _ `  
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