43 
8. The amount of substance soluble in dilute hydrochloric acid. 
9. The amount of clay present. 
10. The quantitative composition. 
From the entire investigation it will be seen that, as in the case 
of the Craigleith bed-rock, water alone dissolves something from 
each stone ; water charged with carbonic acid dissolves an addi- 
tional amount of substance ; and water containing mineral acids, 
effects still farther solution. The conviction I had long entertained, 
that the iron stains in sandstones are occasioned not only by the 
oxidation of iron pyrites, but by the solution of iron in water con- 
taining carbonic acid, and which led to the trial, in the case of the 
Craigleith bed-rock, of the action of carbonic acid water upon its 
powder, is now extended and confirmed. 
The results in full are stated in the succeeding statements by Mr 
Bloxam, who has had the entire charge of the analytical inquiry. 
His interesting observation, that cobalt occurs in Craigleith stone, 
previously announced in relation to its coarser variety, is now ex- 
tended to the denser liver-rock and to the Gifnock sandstone. 
Copper also has been shown to be present in the Binnie sand- 
stone, a metal not hitherto suspected to exist in rocks of its class. 
Mr Bloxam has also pointed out the occurrence of nodules of proto- 
carbonate of iron in the Partick stone, a peculiarity which probably 
will not be found confined to that rock ; since, in truth, it is but the 
most exaggerated form of that occurrence of carbonate of iron in 
sandstones, to which the extraction of iron from them by carbonic 
acid water pointed. Nevertheless, I was quite unprepared for the 
carbonate of iron occurring in separate masses of considerable mag- 
nitude, nor was it in consequence of any hypothesis, but solely by 
careful analysis, that Mr Bloxam made this curious discovery. The 
explicit table which he has constructed, and the commentary which 
precedes it, render any further remarks on my part unnecessary. 
G. W. 
1. Craigleith Liver Sandstone. 
The experiments upon the Craigleith liver sandstone were made 
with carefully-selected specimens of the stone. The results are 
stated in full in the table. 
2. Binnie Sandstone. 
The second stone subjected to analysis was procured from Binnie 
