1822.] Sixth Edition of his System of Chemistry, 263 



another without throwing out remarks which may benefit the 

 reader. Every experimenter has methods of his own, which he 

 has brought to a considerable degree of perfection, though they 

 have probably been overlooked by his fellow labourers. The 

 very circumstance of drawing the attention of chemists to such 

 particulars cannot but improve the art. Nor is it less advanta- 

 geous to compare together the methods followed by different 

 chemists to accomplish the same object. I was sorry to 

 observe nothing of that nature in this part of the Review. The 

 most consummate petulance, accompanied as it always is with 

 the most woful ignorance, characterizes every one of the 

 Reviewer's observations. To enter into a minute refutation of 

 such accusations would be a superfluous task. To the real 

 chemist, their absurdity will appear at a glance ; and those who 

 are not acquainted with the subject are not likely to trouble 

 themselves either with the accusations or the answers. I think 

 it necessary, however, though at the risk of encroaching upon 

 the patience of the reader, to notice every accusation which 

 appears to be of any importance. 



1. Light. — The attack upon my account of light in p. 128 of 

 the Review^ cannot surely require any answer. I am not aware 

 of any thing wrong in my observations, nor do I admit the jus- 

 tice of a single statement advanced by the Reviewer in opposi- 

 tion to them. One specimen of the Reviewer's mode of writing 

 will be amply sufficient for the reader. I say that the " particles 

 of light repel each other, while the particles of other bodies 

 attract each other, and accordingly are found cohering together 

 in masses of more or less magnitude." — (System, voL i. p. 23.) 

 To this the Reviewer subjoins : " This is sad prosing. Have the 

 sun and stars no sensible magnitude ? Do the particles of gaseous 

 bodies cohere together?" (Review, p. 128.) It would appear 

 from this passage, that, in the Reviewer's opinion, the sun and 

 stars are mere masses of hght. Unless he thinks so, his obser- 

 vations are absurd and inapplicable ; and if he does think so, he 

 is a very fit person truly to ridicule the opinions of others 

 respecting light ! The particles of gases do not cohere together, 

 because they repel each other as well as the particles of light. 

 But I should like to know the gaseous body which does not 

 enter as a constituent into some solid or fluid body, whose par* 

 tides cohere. Have we any evidence that hght constitutes a 

 ponderable part of any body? Such is the Reviewer's mode of 

 throwing ridicule on my account of light ! It demonstrates, I 

 think, that the chapter contains nothing upon which he could 

 fix any animadversions ; for could he have pointed out any 

 thing really absurd or inaccurate, the passage about the sun and 

 stars would surely have been omitted. 



2. Expansion. — The Reviewer's observations respecting ex- 

 pansion in p. 130 of the Review, show merely that he has not 



