1813.] On Transition Rocks. 109 



certainly should have perused it with more pleasure than I have 

 done. It is painful to have had to point out so many errors and 

 mistatements in an essay which scarcely contains one fact not 

 previously known to mineralogists, either from the writings of 

 Hutton, of Playfair, of Jameson, or of Berger. When the 

 celebrated Von Buch, in 1806", discovered granite in transition 

 country, he did not immediately infer " that the distinction of 

 transition rocks was thereby proved to be grounded on false con- 

 clusions ; " he only said, that he had been enabled by this obser- 

 vation to add a new member to the transition scries, and thereby 

 increase its importance in the eye of the mineralogist. This was 

 evincing a modesty as well as a sagacity in the great naturalist, 

 which it would have been pleasing to see displayed more conspi- 

 cuously in the " Remarks on Transition Rocks." 



I am, Sir, with much esteem and respect, 



Your most obedient servant, 



James Grierson. 



Article VIII. 



Observations on the Daltoman Theory of Definite Proportions. 

 By Thomas Thomson, M.D. F.R.S. 



{Continued from p. 52.) 



Though the tabic given in the part of this paper already 

 published be pretty long, it contains but a small portion of the 

 numerous chemical compounds known, and analysed with 

 tolerable accuracy, and therefore capable of being referred to 

 the doctrine of definite proportions. 1 shall, therefore, in this 

 and some subsequent Numbers, continue it, as far as the present 

 state of chemical analysis will enable us to go. I shall preserve 

 the same method which I followed in the first part of the table : 

 namely, state below, in the form of notes, the documents upon 

 which the numbers adopted in the table are founded. 



Svlphi/rets. 

 1 10. Sulphurct of gold 



* Gold cannot be united directly with sulphur ; yet both from 

 analogy and from the black | reeipitate which falls when hydro- 

 sulphurct of potash is dropped Into solution of gold, there can br 



