(388 Traksacttoxs of the American Institute. 



inliereiit in tlie bones. Mncli diffieulty -^-as found in reducing the 

 hoofs, until at hxst the plan of subjecting tlie material to the action of 

 superheated steam was hit upon and found to bring it into the required 

 condition. Another fertilizer of similar character is called nitro- 

 phospliate of lime. It is composed of the animal offal before described, 

 and which is rich iu ammonia, mingled in due proportions with super- 

 phosphate. It is claimed by the numufacturers to be equal to Peru- 

 vian guano in its immediate, and more lasting in its remote, effects. 



MiNEKAL SuPEKPnoSPHATES. 



As before intimated, the manufacture of superphosphates is now 

 carried on almost exclusively v.'ith mineral phosphates found in large 

 deposits in various parts of the world, among which those of South 

 Carolina and of the island of Xavassa are among the most available 

 and extensive. Tlie superphospliate made l)y the Lodi manufacturing 

 company is manufactured from equal parts of the phosphates brought 

 from these two localities. The phosphatic material comes in bags, 

 and in a condition as fine as flour, having been ground in a burr-stone 

 mill. It is a yellowish looking substance, as heavy as ordinary plaster. 

 In its natural or unground condition it is so refractory that acids 

 would fail to reduce it, and hence the necessity of grinding. Even 

 in its form of liuur it IkjUIs its phosphoric acid with such tenacity 

 that its application previous to chemical treatment would produce 

 but little good, and as a consequence it must be converted into super- 

 phosphate, which makes the phosphoric acid soluble so that plants 

 may take it up from the earth. This is done by simply putting the 

 ground phosphate in small batches into an iron kettle, and pouring 

 diluted sulphuric acid or oil of vitriol upon it. The oil of vitriol 

 drives out the phosphoric acid from a part of tlie lime, and forms a 

 sulphate of lime. The liberated phosphoric acid immediately unites 

 with the other portion of the phosphate, which thus contains twice as 

 much of the acid as it did before, and constitutes a new chemical 

 product termed superphosphate of lime. Xow, all the phosphoric 

 acid in this superphosphate is soluble, and consequently acts at once 

 when used as a manure. We hei'e close our sketch of the Lodi 

 manufacturing company's woi'ks, devoting a brief space to some 

 matters of general interest connected with the subject, and a few 

 words to the consideration of 



