to vegetable Colours^ and their Mutations thereby. 1 7 1 



evident that we have yet to learn the invariable characteristics 

 of alkalis and acids. We may attempt to cover our ignorance 

 by a free use of the term anomalij ; but 1 do hold that in the 

 universe of God there is no such thing as anomaly." 



After all this, I do own that ]Mr. Faraday's paper on the 

 same subject in Mr. Brande's Journal for 1st instant, pp. 315 

 and 316, surprised me not a little, because I must assimie 

 egotism, though it may appear, that the very humble imorilif 

 of requesting the attention of chemists to this important fact is 

 due to me, as clearly demonstrated by the paper published in 

 your 58 th volume. 



Mr. Faraday, however, is not pleased either to advert to that 

 paper or my name as connected with the subject, and his pa- 

 per concludes in the following language: — "My object has 

 not been to trace these changes as Jar as j^ossiblc, but merely 

 to show their general appearance, and to guard against any 

 deceptive conclusion with respect to solutions tested by Tur- 

 meire, and to call attention to the distinguishing characters of 

 acids and alkalis." In the present vcrij imperfect state of che- 

 mical science we may not be able '" to trace these changes a& 

 far as -possible ;'' and /had already called attention to the de- 

 ceptive conclusions in question. Mr. Faraday has in a former 

 part of this paper observed, " / find on trial, however, so 

 many substances possessing this property," namely, what I had 

 pointed out in the action of subacetate of lead; nitrate and sul- 

 phate of copper, &c. " that," continues this ingenious chemist, 

 " it must either be limited more exactly than has yet been 

 done, or else given up as a distinguishing property," How 

 " limited more exactly ?" It must be given up entirely. 



Mr. Faraday endeavours to account for the change, but the 

 success of this attempt docs not seem quite so evident ; for in 

 one part of his memoir he thinks that it is in consequence of 

 the prolosalts becoming persalts, though he states " submuriate 

 of zinc," &c. " a})peared alkaline to turmeric paper." Further 

 on, it is stilted that " the effect is produced princii)a]ly by the 

 acid present." How can this be, in the case of subacetate of 

 leiul? Does this too become a ;wsfl// ^ But he afterwards 

 remarks that " the whole substance must act." 



Now the truth is, that all that was done before my exjicri- 

 ments, consisted in Desfosses showing that boracic &c. acids 

 reddened turmeric pajjer ; and Mr. F. thinks that South had 

 found that subacetate of lead reddened turmeric paper. It 

 may be so, ti^r any thing I know to the contrary; but / liave 

 never met witli the detail. From all tliis however it was merely 

 supposable tiiat turmeric, as turmeric, was suscej)tible of this 

 change by the action of boracic aci<l, &c. But I have ad- 



Y '2 verted 



