50 FARM AND SCHOOL PROBLEMS. 



Oyster shells contain about 95 per cent calcium carbonate or 

 approximately 43 per cent lime. 



Wood ashes which contain about 5 per cent potash and .1 to 

 1.5 per cent phosphoric acid also contain about 50 per cent cal- 

 cium carbonate. If the calcium carbonate in wood ashes is equal 

 in value to calcium carbonate in ground limestone, which yields 56 

 pounds of lime per hundred pounds, 100 pounds of wood ashes 

 will contain 28 pounds of lime. 



Marl which is a loose deposit of earth consists of clay in- 

 termingled with calcium carbonate. The amount of calcium car- 

 bonate in marl may vary from 10 to 90 per cent. 



PROBLEM. 



If 1,000 pounds of marl contains 60 per cent calcium carbonate of 

 equal value to the same amount of calcium carbonate in limestone, what 

 is the number of pounds of lime contained in the above amount of marl? 



Waste carbonate of lime from soap factories if properly 

 dried may prove to be an excellent form of calcium carbonate. 



Quicklime is jusedi in the .manufacturing -of jfeugar from 

 sugar beets. It is used to purify the juices before their conversion 

 into granulated sugar. Waste lime from the sugar beet factories 

 is partly hydrated and partly carbonated lime. The hydrated 

 lime will change into carbonate and an analysis of lime waste 

 from a sugar beet factory has shown over 42 per cent calcium 

 carbonate. 



PROBLEM. 



How much lime would there be in two tons of this refuse contain- 

 ing 40 per cent calcium carbonate, if this amount of calcium carbonate is 

 equal in value to the same amount of ground limestone (800 Ibs. of 

 calcium carbonate) ? 



Lime is also obtained from water-softening plants and from 

 acetylene gas generators and may be obtained from basic slag 

 which is a by-product from the manufacture of steel from pig 

 iron. 



The important problem in the purchase of any product con- 

 taining carbonate of lime is to determine the percentage of lime 

 than can be obtained. 



