24 CONTROL SERIES NO. 122 



Explanation of Table of Analyses 



Tables I, II, III, "Neutralizing value expressed in terms of calcium oxide" 

 represents the acid neutralizing value of both the magnesium and the calcium. 

 The figures in the "per cent" column are obtained by a direct titration with 

 standard acid. The "pounds in one ton" are secured by multiplying the figures 

 in the "per cent" column by 20. 



"Insoluble matter" represents material which is insoluble in dilute hydrochloric 

 acid to which a few drops of nitric acid have been added, and is mainly sand. 



Table II and III, "Carbonates of calcium and magnesium". Some of the 

 figures in this column include small amounts of calcium and magnesium com- 

 bined as basic silicates: therefore in some cases the sum of the calcium and mag- 

 nesium carbonates and the insoluble matter slightly exceeds 100 per cent. 



Under "Mechanical analysis" the figures represent in round numbers the 

 percentage of product that would pass or be retained by the meshed sieves men- 

 tioned. 



The limestone products have been published in two groups or grades (see 

 tables II and III) according to fineness of grinding and to conform to definitions 

 voted by the Association of Oflicial Agricultural Chemists at their 1936 meeting. 



