NOTES. 



clxi 



trachyte, Professor Rammelsberg was so kind as to undertake it, with his usual 

 precision. I subjoin the results as they were communicated to me by Gustav 

 Rose in a letter in the month of June 1854. " The piece of Chimborazo-rock, 

 which Professor Rammelsberg has submitted to a careful analysis, was broken 

 off from a specimen in your collection, which you had brought from the narrow 

 rocky crest at an elevation of 19,094 feet above the sea. 



" ANALYSIS BY RAMMELSBERG. 

 (Elevation, 19,094 English feet; specific gravity, 2'806.) 



"ANALYSIS BY ABICH. 

 (Elevation, 16,178 English feet ; specific gravity, 2'685.) 



" (In explanation of the above numbers, it is to be remarked that the first co- 

 lumn gives the per-centage of the different constituents, and the second and third 

 the amount of oxygen in them. The second column indicates only the oxygen of 

 the stronger oxydes (which contain 1 atom of oxygen). In the third column 

 this is collected together, for the sake of comparison with the alumina (which is 

 a weak oxyde) and the silicic acid. The fourth column gives the proportion of 

 the oxygen of the silicic acid to the oxygen of all the bases taken together 

 as = 1. In the Chimborazo-trachyte this proportion is ~ 2'33 : 1-0.) 

 VOL. IV. I 



