354 On the Geology of the Baltic. 
I proposed, with all deference, that the Academy of Sciences should 
endeavour to induce the Government to execute a levelling survey 
from the medium level of the sea at Trondhiem to the ordinary or 
medium level of the Gulf of Bothnia, with a view to ascertaining 
if these were identical; in which event, of course, the conclusion would 
stand good as at present ; whereas a contrary result, if at all consi- 
derable in degree, would shew that the observed facts were liable to 
be accounted for without necessarily presuming a movement of the 
land. The learned Professor was at first exceedingly unwilling to 
entertain my doubts; but he at length admitted their weight, and 
undertook to make a report on the subject to the Academy, and for 
this I supplied him with the materials. Of the result 1 have as yet 
heard nothing ; but at least, I trust, I may take this means of warn- 
ing all who feel an interest in the subject against a too implicit trust 
in the theories which have been somewhat over-confidently, if I may 
not say somewhat arrogantly, maintained with regard to the changes 
of the apparent level of the Baltic —(Chambers’s Edinburgh Journal 
for March 1850.) 
Chemical Notices. By ALEXANDER Kemp, Esq., Teacher of 
Practical Chemistry, and Assistant to Dr Gregory, in the 
University of Edinburgh. Communicated by the Author. 
1. On the Purification of Oil of Vitriol from Nitric Acid. 
In consequence of the oil of vitriol of commerce containing a con- 
siderable amount of nitric acid, which renders it unfit for many of 
its applications, I have been induced to make a few experiments on 
the different methods commonly recommended for its removal. 
In the last edition of the Edinburgh Pharmacopeia, we are directed 
to boil the acid along with a small quantity of sugar, until the colour 
first produced disappears. This method was tried by Dr Schlossberger 
and myself, in Professor Gregory’s laboratory in 1845, but without 
success, as we found that we could not remove the whole of the nitric 
acid, even by continuing the process for several days, unless so much 
sugar was added as permanently blackened the liquid. I again tried 
this method a short time ago, and increased the proportion of sugar 
until the acid became quite black, and gave off a large quantity of 
sulphurous acid; after removing this, by long-continued boiling, 
the liquid was diluted with distilled water, but from its dark colour, I 
found it to be impossible to test for nitric acid by the solution of 
proto-sulphate of iron, or by narcotine. It then occurred to me, that 
as chlorine is always produced when nitric or nitrous acids act on 
