209 GEOLOGY AND CHEMISTRY OF SOILS. 



that by the first process, there can be no doubt of the accu- 

 racy of the result. 



4. Place the filter (2) with its contents upon a funnel, and 

 wash with 2 drams of muriatic acid, diluted with 3 times its 

 bulk of cold water. Wash the filter, until tasteless water 

 passes through. The acid will dissolve the carbonate and 

 phosphate of lime; the iron which may arise forming salts of 

 iron, present in the soil ; and the oxide of iron. The two 

 latter exist in very small quantities in most soils, and as the 

 sulphuret and sulphate of iron, in the process of cultivation, 

 are converted into sulphate of lime, the whole may be re- 

 garded as a solution of the salts of lime. Evaporate the solu- 

 tion to dryness, weigh it, and it will give the quantity of these 

 salts. 



5. To separate these salts, dissolve them in boiling water. 

 A part will be insoluble. Throw the whole upon a filter, and 

 weigh as above. The insoluble portions will be phosphate of 

 lime, and the loss will be the sulphate of lime. Note the 

 quantity of each. 



6. To determine the quantity of insoluble geine. The re- 

 sidual soil may now be burned in a silver or platina crucible, 

 and the loss of weight will give the quantity of insoluble geine 

 contained in the soil. The only source of error here, will be 

 due to the loss of water in any hydrate which may exist in the 

 mass burned. But it is found by experiment, that in our 

 soils the quantity is rarely sufficient to affect materially the 

 result. 



7. The weight of the mass after calcination is *' granitic 

 sand," composed mostly of clay, mica and quartz, all of 

 which may be tested by methods already given. 



It will be seen, that by this process the quantity of lime is 

 not detected, but this is of very rare occurrence in the soils 

 of this country. From an analysis of one hundred and twen- 

 ty five specimens of soils, taken from as many towns in Mas- 

 sachusetts, only seven contained any quantity of carbonate of 



