3 

 stone near tlie surface where contamination by earthy matter is not unusual. Tlie 

 raw ground limestones sold in Massachusetts are as a whole in a satisfactory 

 mechanical condition, only one brand out of 11 sold showing less than 70 per 

 cent that would pass through a 100-mesh sieve. The exception noted was the 

 product made by the Hoosac Valley Lime Co., Inc. Only 42 per cent of this 

 passed a 100-mesh sieve. About 80 per cent should pass a 100-mesh sieve to be 

 equally effective with the hydrated products. 



No deficiencies were noted in case of the gypsum products, although the one 

 put out by the Atlantic Gypsum Products Co. carried a relatively large amount 

 of carbonate of lime, which reduced in proportion the amount of calcium sulfate 

 present. 



Explanation of Tables of Analyses. 



Table I, "Proportion of total oxides as carbonates." The data furnished in this 

 column are calculated from an actual determination of carbon dioxide (CO2). 

 Calcium or magnesium not in the form of carbonate is present either as hydrated 

 (water- or air-slaked) or as burned lime (caustic or unslaked). It should be 

 understood that all of the products listed in this table have at some time been 

 burned, and the proportion of oxides present as carbonates indicates to what 

 extent the product has absorbed carbonic acid from the air. 



"Pounds of effective oxides in one ton" represents the sum of the calcium and 

 magnesium oxides in one ton of the lime product, assuming that both ingredients 

 from this source will become readily available. 



The calculations found in column "Cost of 100 pounds of eflPective oxides" 

 are based on prices furnished by the producers. 



Table II, "Pounds of effective oxides in one ton." In securing these data the 

 degree of fineness to which the limestone has been ground is taken into con- 

 sideration. On those products which are finely ground so that all of the material 

 will pass through a 20-mesh sieve, it is assumed that all of the calcium and mag- 

 nesium oxides will become available in the soil within a five-year period. On 

 those products which will not wholly pass a 20-mesh sieve, it is assumed that the 

 oxides in that portion which is coarser than 20-mesh will be only 50 per cent 

 effective during the same period. 



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

 percentage of product that would pass the various meshed sieves mentioned. 



In both tables the figures in parenthesis following the brand name show the 

 number of samples collected and analyzed. 



