FARMERS' REGISTER. 



407 



richest lands in the United States contained liilie 

 or no "calcareous earth," — to lament that this, il 

 considered alone, should excite doulils of ihe im- 

 poriant truth that calcareous earth crcatly i)ro- 

 niotes the I'eriiliiy of soils, if not essentially ne- 

 cessary to such leriilily — and tosuuirei^t a niude oi 

 explaining the appMrent, Incnnsisicncy. Il' the 

 richest lands in the Uniied SiiHes contain no cal- 

 careous earih, then such earih is not es.-^ential to 

 fert lily ;— does it really proaiote Jertiliiy in any 

 land ? 



I helieve that Mr. Riiffinis in an error, and that 

 from his not being sutTicierUly ac(]uainled with 

 cheniisiry, he had not carried ihe analysis ofthese 

 rich lands i'ar enough, or he would probably have 

 discovered in them sulphate of lime (plaster of 

 Paris), or oxalate of lime, or both. Neither of 

 these calcareous earths can be discovered in the 

 usual way of analyzing soils, yet they are believed 

 to be among Ihe most povverlul of calcareous 

 manures, and very likely lo be Ibrmed in our soils 

 by the natural decomposition of some substances, 

 and the subsequent combination of the oxalic and 

 sulphuric acids with lime in these soils. 1 meant 

 only to explain away a doubt or difficulty, in a 

 way that I had not seen it explained by any one 

 else, and thereby to encourage all who doubled, 

 to go and try the calcareous earths on their lands. 

 We are all liable to errors as well as Mr. Ruffin ; 

 it is only surprising that but one error can be sug- 

 gested against him, and that, evidently the result 

 of his not having gone far enough in the analysis 

 ofthese rich lands. In this opinion, I myself may 

 be in an error, and some third person may be 

 found, to correct us both in our premature con- 

 clusions. 



Doubts have been intimated bj- others, besides 

 Mr. Ruffin, as to the general existence of so large 

 a proporiion of magnesia in the calcareous earths 

 of South-Carolina. I will state my mode of pro- 

 cedure, and let others repeal it, eliher to confirm 

 or disprove the result. Having dried the cal- 

 careous matter, I weigh one hundred grains of it 

 in powder and dissolve it in diluted muriatic acid. 

 When the etl'ervescence has subsided, I decant 

 the clear solution and wash the earthy residue so 

 as to separate all that is soluble about it. These 

 washings are added to the clear solution, and the 

 earth dried. I generally guess from its appearance 

 when dry, as to the f'roporlions of clay and sand. 

 I then try the solution with blue paper, and if it 

 contain an excess of acid, I neutralize that with a 

 solution of [)oiash. 1 then pour into it a solution 

 of oxalic acid, until it is a little in excess, and stir 

 the mixture lor a lew minutes, to promote the 

 union ot this acid with the lime previously united 

 Avith muriatic acid in solution. The oxalate of 

 lime thus precipitated is washed, dried on filtering 

 paper, and weighed. I genet^ally set down one 

 half of this weight as the proportion oflime found 

 in it. The residue of the solution I precipitate 

 with potash, and obtain the carbonate of magnesia 

 which subsides, and is then washed, filtered, dried 

 and weighed. 1 may not have mixed a sufficiency 

 of the oxalic acid to precipitate the whole of the 

 lime, and in that way some of it may have been 

 mixed with the magnesia, so as to give too great 

 a proportion of the latter. All the books speak of 

 magnesia as generally found in lime stones, and I 

 have no doubt of the fiict in these cases. 

 The chief cause of misunderstanding between 



Mr. Ruffin and myself, is, the precarious meaning 

 of the terms used. He prelt^rsthe term calcareous 

 earih, thereby meaning carbonate of lime, as I 

 have since learned by reference to his book. I 

 read that book about three years ago, but did not 

 recollect his meaning as there explained. I sup- 

 piised calcareous earih lo mean "lime"' in every 

 l()rm and combination in which it is found in the 

 earih. I submit to the candor of your readers, and 

 of Mr. Ruffin, whether 1 am not excusable for the 

 misiake, as I had not his explanation before me. 

 I bought the first ediiion of his work three years 

 .,;o, and did not know until now that there was a 

 second edition. Let me request, through you, 

 that he would send on some of them for sale in 

 Charleston, as ihere are none to be found in the 

 book-stores or libraries. Jos. Johnson. 



It is but justice to Dr. Johnson to republish his 

 rejoinder, as above. The admission of error made 

 therein, as to a supposed position of the author of 

 the ' Essay on Calcareous Manures,' is amply suffi- 

 cient, and he has no desire to contest any other 

 question raised. He never assumed that his re- 

 ported examinations of soils, to ascertain the con- 

 tents, or absence, of carbonate of lime only, were 

 otherwise than partial, and limited lo that one sub- 

 stance; in regard to which, however, he claims 

 to have been accurate. As to his particular ap- 

 plication of the term "calcareous earth," as made 

 throughout the essay, he staled at length the diffi- 

 culty attending it, and still more of every preceding 

 author's different definition or application of that 

 term ; and gave his reasons for limiting it to the 

 carbonate of l\me. (Appendix, p. 72.) And these 

 several applications were not only in the second 

 edition, to which we referred, but in the first also. 

 In using the expression, "as to matters person- 

 al " — we did not mean, as Dr. Johnson supposes, 

 that we dremed them personally offensive, but 

 literally and simply as relating to the author per- 

 sonally. In striking the balance between the re- 

 marks of Dr. Johnson in approval and in censure 

 of the work, we thought then, as now, that the 

 former preponderated. 



We meant not lo "intimate doubts," as to the 

 remarkable and general abundance of carbonate 

 of magnesia discovered by Dr. Johnson in the 

 marls of South Carolina. But the fact is so re- 

 markable, and may be fraught with such impor- 

 tant consequences in the use of the manure, that 

 it certainly, as we said, "requires attention and 

 flill investigation " before admitting its certainty ; 

 and that investigation we hope that Dr. Johnson 

 will give. We have seen, and analyzed, a spe- 

 cimen of one bed only of magnesian marl found 

 in Virginia; and that, with all the specimens 

 of marl from South Carolina which we have seen 

 agreed in the one respect, of seeming rather a soft 

 rock of homogeneous texture, and not a mixture 

 of fossil shells and eand like what are called marls 



