The product was used in a trial experiment on a farm in Leverett, Mass., on 

 soil with a pH of 4.8, showing the characteristic chlorosis accompanying magnesia 

 deficiency. The crops were potatoes, corn and oats. The application of 400 to 

 600 pounds per acre prevented the chlorosis. 



The analysis of the sample drawn in the spring of 1936, strong hydrocliloric 

 acid being used as the solvent, gave the following results: 



Magnesium oxide . 

 Calcium oxide . . . . 

 Iron and aluminum oxides 

 Insoluble material . 



Tests made at this laboratory on other samples show the presence of con- 

 siderable carbon dioxide, indicating that the product is not a true talc (silicate 

 of magnesia) but rather a mixture of talc and magnesite (carbonate of magnesia). 



Lime Definitions 



The following definitions of lime products used in agriculture were made official 

 by vote of the Association of Official Agricultural Chemists at their annual meet- 

 ing in December 1936. It is hoped that so far as possible the branding of lime 

 products used in agriculture will be made to conform to these definitions. This 

 office will be glad to cooperate with any manufacturer in advising with reference 

 to necessarj^ changes in order to conform to these definitions. 



1. Air-slaked lime. A product composed of variant proportions of the oxide, 

 liydroxide and carbonate of calcium, or calcium and magnesium, and derived 

 fiom exposure of quicklime. 



2. Pulverized limestone, (fine-ground limestone) is the product obtained 

 by grinding either calcareous or dolomitic lime.stone so that all of the material 

 will pass a 20-mesh sieve and at least seventy-five (75%) per cent will pass a 

 100-mesh sieve. 



3. Ground limestone, (coarse-ground limestone) is the product obtained 

 by grinding either calcareous or dolomitic limestone so that all of the material 

 will pass a 10-mesh sieve, and at least fifty per cent (50%) will pass a 100-mesh 

 .sieve. 



4. Ground shells is the product obtained by grinding the shells of moUusks 

 so that not less than fifty per cent (50%) shall pass a 100-mesh sieve. The product 

 shall also carry the name of the mollusk from which said product i« made. 



5. Ground shell marl is the product obtained by grinding natural deposits 

 of shell marl so that at least seventy-five per cent (75%) shall pass a 100-mesh 

 sieve. 



PUBUCATION OF THIS DoCtTMENT APPROVED BT THE COMMISSION ON ADMINISTRATION AND FINANCE 



300-l-'37. No. 9477. 



