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THE GENESEE FAEMEE. 



in his manure, are cheaper in London than in New York ; and further, we have said, 

 and are able to prove, that if S. W. Johnson's analysis of Mapes' improved superphos- 

 phate of lime can be relied upon, there is a superphosphate of lime made in London, in 

 every respect as good as Mr. Mapes', and of which many thousand tons are annually 

 sold at wholesale for $28.22 per ton. 



This brings us to another point. The analysis of " Mapes' improved superphosphate 

 of lime" by S. W. Johnson, published in the Country Gentleman of March 3d, has 

 been pronounced by Mr. Mapes erroneous ; and he stated that the error lay so palpably 

 on the face of it, that if no one else pointed it out he should feel obliged to do it him- 

 self. For the credit of science be it recorded, that there is at least one other chemist 

 in the United States beside Mr. Mapes who has discovered the errors of Mr. Johnson's 

 analysis. This learned individual is Dr. Enderlin, of New York — according to Mr. 

 Mapes one of the first chemists of the age, and a gentleman who, according to his own 

 statements, has made many valuable discoveries in chemical science. We are rather 

 surprised that such a great and learned man should be so much a sycophant as this 

 reply to S. W. Johnson indicates. 



Were Mr. Johnson at home we should, of course, not interfere in the controversy ; 

 but as that gentleman is now in Europe, it may not be out of place to examine briefly 

 this attack on his scientific reputation. 



The first great error Dr. Enderlin points out is, that Mr. Johnson calls the phos- 

 phate of lime found in bones, coprolithes, apatite, (fee, &c., " neutral " phosphate instead 

 of " basic" phosphate ; he gives the true composition, but makes a mistake in the name. 

 To correct this grevious nominal error, the learned critic devotes two columns of closely 

 printed matter. • Now, Mi-. Johnson was writing for practical agriculturists, and wished 

 to make his meaning as intelligible as jDOssible. lie doubtless knew, as well as the pro- 

 found Dr. E., that there were other compounds of phosphoric acid and lime ; but he 

 also knew that the only two compounds that concerned the agriculturist in relation to 

 superphosphate were the bone earth phosphate of lime, a,nd the superphosphate of lime ; 

 the one insoluble in water, the other quite soluble. Now, to convert the one into the 

 other we add sulphuric acid, which takes away a portion of lime, producing a compound 

 containing more phosphoric acid than the original phosphate. Mr. Johnson calls the 

 first compound neutral phosphate, and the other the acid phosphate. Can Dr. E. give 

 us two names that would convey a more distinct idea of the two compounds ? 



Another error is thus stated : "That no phosphoric acid is set free which could com- 

 bine with the undecomposed phosphate (as Mr. Johnson thinks to be the case) is easily 

 to be understood from the above exposition of the chemical process." The exposition 

 is this : th-e phosphate of lime contains three atoms of lime united with one atom of 

 phosphoric acid ; the superphosphate of lime contains one atom of lime united with 

 one atom of phosphoric acid. Now, when we add to phosphate of lime two atoms of 

 sulphuric acid, two of the lime are taken away, and the remaining atom of lime is united 

 with the atom of phosphoric acid. Admitting this exposition to be true, is not phos- 

 phoric acid set free, and does it not unite with the undecomposed phosphate, as Mr. 

 Johnson supposed ? We can understand the process in no other way. The phosphoric 

 acid is combined with the tvhole of the lime ; the two atoms of lime do not exist 

 separately. When part of the lime is taken away the phosphoric acid united with it 

 must, for ought we can see to the contrary, be set free prior to its combination with the 

 remaining undecomposed phosphate whereby it forms the superphosphate of lime. 

 This is the second great error of Mr. Johnson. 



The third is still more egregious, and is thus stated : " That no free sulphuric acid can 



be present in such a manure when the named proportions of sulphuric acid and bone earth 



are employed, and the mixture is carefully and thoroughly stirred up and left at rest for 



-, |. . a sufiicient time, is perfectly evident. Nevertheless, Mr. Johnson found, against all chem- 



