126 Mr. Gray's Reply to the Editor. [Feb. 



reject those which are offered to our enjoyment. I have indeed 

 little doubt but that the term hydriodic was an accidental error 

 of Gay-Lussac, or of his printer, and has been perpetuated like 

 the etiolation of Fourcroy in his Systeme, instead of etoilation ; 

 or the laplysia of Linnaeus in his Systema Naturae, 12th edition, 

 instead of aplysia; which have been so often repeated, that they 

 are become standard errors, and bid fair to supplant the true 

 orthography, and disconcert the etymologists. 



Your observations respecting arsenious acid are partly just; 

 the directions respecting testing for arsenic are, I confess, 

 imperfect and incorrect ; but it was not my intention to enter 

 upon the subject of forensic medicine ; and 1 have always taught 

 my own pupils that nothing short of the production of true 

 metallic arsenic will justify a medical practitioner to condemn a 

 supposed poisoner in cases which are in any way dubious. 

 Fortunately as arsenic is cheap, and almost always used by igno- 

 rant persons, they administer it in such quantities that dubious 

 cases seldom occur. I cannot, however, possibly conceive how 

 you could make the following assertion : — " Nor is the direct 

 evidence by metallization in any way alluded to," unless by again 

 supposing that another whole paragraph has, by some strange 

 fatality, dropped out at press from your copy ; for the very next 

 paragraph, in p. 151, to the one you quote, treats of the metalli- 

 zation of white arsenic by the addition of a subcarbonate of 

 potasse and charcoal dust. 



Again passing over for a moment one of your observations, I 

 proceed to the concluding paragraph, which is indeed the cause 

 of my troubling you with this notice of your review. Man is 

 always subject to error, and therefore the mention of a few 

 errors in my Elements, which I am conscious must, like every 

 work hitherto published, or that ever will be published, contain 

 a few, and I hope but a few, would not have been any other way 

 noticed by me, but by silently amending them in any future 

 work. But I am charged with dividing chemists into rational 

 and irrational, and placing Sir Humphry Davy among the irra- 

 tional chemists. Now I think I may fairly challenge you to 

 produce the word irrational from any part of the book. A cau- 

 tious habit of distinction, that I have acquired, and of the want 

 of which in the generality of publishing chemists I have several 

 times complained, has led me to distinguish between pure che- 

 mists, pharmaceutical chemists, and I believe technical chemists, 

 not as words of reproach, but of distinction. So I have men- 

 tioned publishing chemists to distinguish them from mere 

 amateurs, or those who either labour only for themselves, or 

 thpse who are too modest to appear before the tribunal of the 

 public. And again in point of theory, every professor, and 

 indeed almost every chemist, has some peculiar doctrines of his 

 own ; but they may, and accordingly have been by me, divided 



