Dr. Thomson— awrf his Answer. 343 



account of this very valuable and elaborate paper, which we 

 conceive to be one of the most perfect specimens of analytical 

 research, that the author has produced*." This future occasion 

 never arrived; but in his new edition Dr. Thomson assumes 

 for himself the main part of the honour, which in the first 

 moment of admiration, he here gives to the English philosopher. 

 When he published the preceding abstract, he set up no claims 

 of anticipation. He doesnot there say, as in the sixth edition of 

 his System; " The analysis, of phosphorous acid, given by Davy, 

 in his paper published in the Philosophical Transactions for 1818, 

 exactly agrees with mine, and serves, of course, to confirm itt." 

 Now the Doctor's last decision, prior to Sir H. Davy's paper, is 

 to be found in his fifth edition, published about six months be- 

 fore. Here he says, " It will appear in a subsequent part of 

 this section, that phosphorous acid is composed of l..'> phos- 

 phorus and two oxygen." *' Thus the acids of phosphorus are 

 composed as follows : 



Dr. Thomson. Sir H. Daw. 



Phosph. Oxygen." Phosph. Oxygen. 



Hypophosphoric acid 1.5 : 1 .... 3 : 1 



Phosphorous acid 1.5 : 2 .... 1.5: 1 

 Phosphoric acid J. 5 : 3^" .. 1.5: 2 



Our readers may apply to the preceding sample of critical 

 chicane, any epithet which they please. 



With regard to the thermometer, we again affirm that his ac- 

 count of it is contemptible, for he gives no directions whatever, 

 how this indispensible instrument of chemical research may be 

 constructed, or ho^w its indications may be verified. This is the 

 more necessary, as the greater part of thermometers are very 

 incorrectly made. The notice compatible with a manual for 

 general students, is surely very different from what we are en- 

 titled to expect in a system. In lieu of printed information, 

 the Professor invites us to attend his lectures on the subject at 

 Glasgow, which invitation we have already given reason for 

 declining. Indeed we had rather attend a Dutch prelection on 

 Puffendorf. 



In the number of Thomson's Annals published on the first of 

 June, 1815, we find a copious abstract of Sir H. Davy's paper 

 on the deutoxide of chlorine, read to the Royal Society on the 

 preceding 4th of May. In Gilbert's Annalen for February 

 following, that is eight months after Thomson's promulgation, 

 and nine months after the above public reading, we have an ac- 

 count of what Dr. Thomson, in one page of his system calls 

 •' Count Von Stadion's deutoxide of chlorine, discovered about 

 the same time ;" but of which, he says with his usual inconsis- 

 tency in the next page, " it differs so much from the gas ex- 

 amined by Davy,thatitis probable they are distinct substances." 



• Thornton's Annals, XI. 382. f Systtm, 6th Ed. I. 263. 



: System 5th Ed. I. 366. 



