CHEMICAL THEORY. Q3 



be revived by setting or strapping. Instead of ibis procobs, -r^ettlng ic- 



however, let it reraain exposed to the effects of the atmosphere. Produces them: 



If it be thus left for a suHicient time, it will become oxided or _but if lai-i a- 



quite rusty : but before this happens, it is reasonable to admit ^*^*' ^^^ '^^^f" 



^r ^ •••II rr •,. , will rust, in 



that an invisible effect will be produced on its thinest part or timci 



edge ; or in other words, that it will be corroded by the joint P'-^iti-^ularly on 



action of the water, carbonic acid,and oxigen of iheaf mosphcrc. " ' 



We have seen in the sabre that the iron is corroded before the 



Steel ; and in one of fine Damascus structure the iron parts will — and that va* 



be oxided and the steel parts left, — that is to say. the edge ^'l^^'ly. fo as 

 . * •' ' '^ to reprou)ire 



Will again spontaneously become toothed, and the razor of con- teeth and re- 

 sequence sharper than before. ^^°^^ *^^ edge. 

 The use of strapping is to render the edge finer than that strappinj? may- 



which comes from the hone. If wc imagine the atmospheric rena'er the edge 



... . . , ^ • liner, or clear 



oxidation or corrosion to give a somewliat coarse edge (which away the ux- 



it must do if it revives an edge that was t-oo dull for the ''^^• 



§trap), the use of the strap mentioned by E. D. will be to do 



the same in the present case. Or perhaps it may be of use to 



carry away the oxide with which the chemically formed 



notches will be clogged. 



It is with great satisfaction that I find the delay respecting Cancernin? the 

 my promise in the place cited (xiii. p. 8-t.) so well compensa- claims of La- 

 ted for in the postscript to E. D.'s letter. Confinement by^'"'"'^^* 

 illness, and the pressure of many objects of business by that 

 means increased, were the causes of that delay. I fully agree All our theories 



with him that all our theories of chemistry, viz. of heat, com- ?*"c^^™stry 

 , . -^ ' imperfect, 



bustion, and the afimities, are crude, hypothetical, and unworthy' 



of the importance which is attached to them ; though the dis- 

 coveries of facts relating to each are such as do honour to the 

 sagacity of the great men who have laboured in those several 

 departments of research. I hope to be able shortly to 

 state so much of the history as may extend the observations of 

 my ingenious correspondent In settling the claim of M. Lavoi- 

 sier to which he has attended. The mischiefs a.s well as the General analo- 



merits of -generalizing are intitled to the serious attention ^'^'^ f*'*' .^^ °^' 

 - , ., " .ten detnmea- 



ot philosophers ; and the integrity of any claimant, whose dc- tal as beneficial 

 mands are not well founded, can only be vindicated by a sup- ^^ s^'^nce, - 

 position that he did not know the true owners of that which 



he may profess to have found. INI. Lavoisier well knew the '^h ^'*''^'^'^'' 



did attempt to 

 claiuis obtain Jiouor 



