390 Further Remarks upon Mr. Herapath's Theory. [Nov. 



with nitrate of baryta, and the other processes usually adopted, 

 I found it to be composed of oxide of copper, mixed with a large 

 proportion of silica, and a small quantity of lime and potassa. 

 The colouring matter is, therefore, evidently copper ; and from 

 the presence of the alkali, the pigment is probably an artificial 

 production ; and since I could discover no trace of any other 

 metal, except an almost imperceptible one of iron, its preparation 

 must, in all likelihood, have been conducted with equal skill and 

 care. 



The small portion soluble in acids seems to have derived that 

 property from a partial decomposition of the pigment, which may 

 well have been effected, by the action of (he oil used as the 

 vehicle to mix it up with, and other natural causes, in the long 

 succession of ages that have rolled away since its first appli- 

 cation. Yours, &c. 



J. G. Children. 



Article VIII. 



Further Remarks upon Mr. Herapath's Theory. 



(To the Editor of the Annals of Philosophy.) 

 SIR, 



The following remarks were drawn up in continuation of 

 some, which you did me the favour to insert in your number for 

 September, before your number for October reached me. In 

 that number I found Mr. Herapath's reply to my remarks, on 

 which account I wish to premise, with respect to that reply, that, 

 in the first place, I am not aware of anything " ungentlemanly" 

 in my remarks ; and should any expression be thought so, I here 

 beg to apologize to Mr. H. for it. 1 also wish to assure him that 

 I am actuated by no motives of jealousy, and that any difference 

 between him and the Royal Society can have had no influence 

 whatever on my views of his theory, as 1 am not a member of 

 the Royal Society, nor in any way interested in opposing his 

 theory. My design was merely to state, without offence, one or 

 two difficulties which occurred to me on reading his papers ; and 

 this I assure him I have done repeatedly, and with the greatest 

 attention. The advice also which he gives me in his reply I 

 have faithfully followed ; and upon the most careful re-examina- 

 tion of both sides of the question, I must say, that with respect 

 to the main and fundamental parts of his theory, I have found 

 no reason to change my opinion . He accuses me of misrepre- 

 sentation ; I candidly and openly acknowledge that I have found 

 one or two observations (but of little or no importance) which I 

 would wish to retract. Mr. H. will easily perceive which I 



