45 i Letter from Mr Low of Annfigld* Nov* 



fumed in the burnlnjT of the ftone ; and, as far as they prevail, 

 aid the burning. The only way to afcertain what proportion the 

 cuhn bears to the mafs, is to analyze the Hme after it is com- 

 pletely burnt. Were this done, I have no hefitation in faying, 

 that your limeftone approaches more to abfoJute purity than the 

 Sunderland, or, perhaps, any other limeftone in the world. 



* You can eafily fee the great utility of chemical analyfis. I 

 have often pitied a poor man, when I faw him taking a long jour- 

 ney, and loading his carts with a greater proportion of clay or 

 fand, than of pure lime -, or when I faw him carrying even good 

 lime imperfectly burnt. 



* Were all limeftone analyzed, every man would know what he 

 was doing who ufed lime ; and thofe who ferve the public v,'ith 

 lime fhould take care that it is well burnt, otherwife they im- 

 pofe upon their cuftomers a load wholly ufelefs to them. When 

 lime is to be ufed on the fpot where it is manufactured, thefe 

 things are of lefs importance ; but when conveyed to any dif- 

 ftance, they are of the utmofl moment. * 



The above, Sir, is a literal tranfcript of Mr Headrick's let- 

 ter ; and I prefume Sir Gecrge M'Kenzie will confider it as a 

 full anfwer to his queflion. I beg leave to think that he has 

 made rather ftrong remarks on A. S.'s letter, efpecially as his 

 own manner of analyzing lime and marl feems to turn out 

 the fame as that of A. S., whofe only error Sir George con- 

 cludes to be a too great confidence in the correclnefs of the 

 apothecary who prepares the acid. It might perhaps be well 

 that every drug an apothecary may fell was alfo previoufly pu- 

 rified. But does the phyfician doubt the pure quality of the 

 medicines he prefcribes to his patient from a creditable labora- 

 tory ? No : he prefumes them pure as they ought to be. Muft 

 not candour therefore pronounce many of the obfervations of 

 Sir George to be frivolous -, and as it is not necefPary to farmers 

 to learn to analyze lime to m'rnute7iefiy A. S. feems to go as far 

 as eflential in dire6ting them how to know the compavuiive va- 

 lue of different limes. The experiments would naturally be 

 made on the different limes at the fame times by the fame acid i 

 and the different refults would be fo very nearly in the ratio of 

 their purity as to be a matter of little moment to carry the pro- 

 'cefs to mathematical exa6tnefs. I beg alfo to remark, that 

 A. S.'s theory of analyzation is not only the fame as that of the 

 great chemift Dr Black, and the Bifliop of Llandaff, but that of 

 Sir George himfelf, with this diflintlion only, that he does not 

 confider it as abfolutely effential to afcertain whether the alloy 

 be filex, argil, or oxyd of iron. 1 remain, Sir, your moll obe- 

 dient fervant, 



Annfidd^ Oct, 2d, 1804. Alex. Low. 



