42 



Magnesian Lime. 



Vol. VII. 



vegetation in all quantities and proportions, 

 is not supported by analogous facts, with re- 

 spect to other earths. 



He says, many farmers in Delaware are 

 very particular with respect to the purity of 

 the lime they use; " One of them informed 

 me, that some of the Schuylkill lime is so 

 impregnated with magnesia, that it is not 

 worth buying ; and other kinds so pure, that 

 you cannot buy too much of it." Then fol- 

 lows the stereotyped authority of Tenant and 

 others, " that magnesian lime is exceeding- 

 ly injurious to land." Now, if this know! 

 edge or opinion of these farmers, is the result 

 of a vigorous chemical analysis, conducted by 

 themselves — for it does not appear that any 

 body else examined it — I must congratulate 

 them on their advancement in chemical 

 knowledge; such attainments were certainly 

 very rare among such farmers as I mixed 

 with some years ago ; but that was in the 

 fir iii xhtcd county of Chester, where itseem3 

 that the farmers long cherished an inveterate 

 prejudice, against all book-learning. But if 

 they are mere opinions, formed without any 

 knowledge of the true composition of the 

 article they were using, what reliance can 

 be placed on them as a foundation for, or 

 proofs in support of, a very important theory] 

 It is against attempts to base a theory on 

 mere opinions, assumed as facts, and from 

 such a theory deducing very important prac- 

 tical consequences, that I have all along been 

 contending; if in doing this I have used 

 strong language, it was not for the purpose 

 of irritating any one, but to arouse attention, 

 and direct inquiry to the subject, and bring 

 theory to the test of facts and practice, closely 

 and vigorously investigated. We have had 

 namby-pamby essays enough on the subject, 

 leaning on the authority of great names, and 

 meaning anything or nothing, just as you 



". My design was to state explicitly 

 for what I was contending, that my views 

 need not be misunderstood, and if erroneous 

 they might be shown to be so ; but in this I 

 may have tailed. 1 have stated it as a fact, 

 that immense benefit has been derived from 



-" of lime in agriculture, in South-east- 

 ern Pennsylvania, and parts adjacent, and 

 that the whole improvement in agriculture, 

 so far as lime is concerned, is due to magne- 

 sian lime and to none other. I also stated 

 it is as a probable conjecture, though not 

 an ascertained fact, that magnesian lime was 

 better, or at least more economical, for some 

 purposes of the tanner, than pure lime. 



The first of these propositions your cor- 

 respondents admit, with a salvo, however* 

 that the improvement might have been 

 greater, if pure, instead of magnesian lime, 

 had been used. Upon the second point then, 



the whole controversy turns: Is, or is not 

 the great body of the limstone of South-east- 

 ern Pennsylvania, of the magnesian variety? 

 All the authorities within my reach, go to 

 prove the affirmative of this proposition. 

 Judge Cooper, many years ago, analyzed 

 several specimens from the great valley of 

 Chester and Montgomery counties, collected 

 between Coatesville and the Schuylkill ; all 

 or nearly all of which proved, if my memory 

 serves me, highly magnesian. Several years 

 afterwards, the late Dr. Joseph Coates of 

 Downingtown, analyzed several specimens 

 from that neighbourhood, which all proved of 

 the same character. The analyses of four 

 specimens from the same district of country, 

 contained in page 309 of Vol. 4 of the Cabi- 

 net, show them all to contain magnesia; 

 three of them, however, in but small propor- 

 tions; those, however, it may be remarked, 

 are from quarries which have not been largely 

 used for agricultural purposes; while the 

 other containing 41 per cent, of magnesia, 

 is from a quarry whence immense quantities 

 have been taken for those purposes. Pro- 

 fessor H. D. Rogers, the state Geologist, in 

 a letter which I received from him some time 

 ago, states explicitly, that " a very large ex- 

 cess of magnesian limestone, compared with 

 the pure carbonate of lime, exists in the coun- 

 ties of Lancaster, Chester and Montgomery ;" 

 and then adds, " indeed, if I were to confine 

 myself to the great valley of Montgomery 

 and Chester counties, I might say, that lime- 

 stone, free from magnesia, is of rather rare 

 occurrence; the quantity of magnesia, 

 varying in different layers of rock, from 5 

 or 10 to 40 per cent. The proportion of 

 magnesian limestone, in the secondary blue 

 limestone of the Kittatiny valley, and the 

 Pequea valley, &c, of Lancaster county, is 

 not so great, yet it is difficult to find a quarry 

 in which it docs not abound." He further 

 adds, that many of the limestones long in 

 use by the farmers of Europe, are as magne- 

 sian as our own. 



Your correspondent, C. Taylor, thinks I 

 use an expression two strong entirely, when 

 I say, that whatever part of the improvement 

 in South-eastern Pennsylvania, is owing to 

 lime, is owing to magnesian lime, and none 

 other ; but is it stronger than the above au- 

 thorities will warrant in the absence of all 

 evidence to the contrary? It was only of its 

 genera} character I spoke. It cannot be ex- 

 pected that we should analyze every stone 

 or layer of rock that has been used, but only 

 enough to show that magnesia does gener- 

 ally and largely abound. 



With respect to the effect produced by 

 any particular lot of lime, we are always 

 willing to take the opinion of intelligent 



