168 Trans. Acad. Sci. of St. Louis. 



This same specimen of quick lime after ignition over the 

 blast lamp and immediate hydration gave the following : — 



Per Cent of Water Per Cent of Lime by 



taken up. Calculation. 



32.30 100.50 



32.36 100.70 



Thus showing the extent to which the lime had been acted 

 upon by the moisture and carbon dioxide of the air. 



The method is also well adapted for rapidly determining the 

 value of limestones for the purpose of making quick lime. 

 Thus a small quantity of the limestone is weighed in a platinum 

 crucible then ignited with the blast lamp and after weighing 

 the quick lime is hydrated by this method. From the weight 

 of water taken up the per cent of lime is calculated. The 

 first series of determinations given above show what results 

 would be obtained with a pure limestone such as Iceland spar 

 or calcite. The following determinations were made with a 

 siliceous dolomite from Arkansas : — 



Weight of Water 

 Weight of Dolomite. taken up. Per Cent of Lime. 



.2974 .0137 14.33 



.2896 .0134 14.40 



HYDRATION OF DEAD BURNT LIME. 



It is generally believed by practical men that lime that has 

 been very highly heated becomes dead burnt or inert to water. 

 Statements to this effect are found in chemical literature. 

 Thus Dammer, Handbuch der Anorganischen Chemie, II, 

 2, 294, states that very high temperatures must be avoided in 

 the preparation of lime, especially if impure calcium carbo- 



