Correspondence.—Physical Features, etc., of Florida. 407 
EXPLANATION OF THE TABLE. 
The formula at the head of each series is a general expression 
for the atomic weights of that series. 'The names of the series 
are derived from the ‘‘ Common Differences,” which are the num- 
bers multiplied by » in the general formule. In the columns 
headed ‘“ ‘Theoretical’ are given the atomic weights calculated 
from these formule and the values of n given in the last columns 
at the right of each division of the table. In the columns headed 
“Observed” will be found the observed values of the same atomic 
weights. These have been taken from the table of atomic weights 
given in the last volume of Liebig and Kopp’s Jahresbericht (for 
1852), with the exception of those against which are placed the 
initials of the observers. The last were taken from Weber’s 
Alomgewichts Tabellen. In some cases the atomic weight is 
taken at twice its received value, but it is then underlined. The 
compounds in any one column at the right of the names of the 
elements are homologous. In the same way, those in any one at 
the left are isomorphous. The numbers at the head of these last 
columns indicate crystalline systems as follows: 1. Monometric ; 
imetric ; Trimetric; 4. Monoclinic; 5. Triclinic; 6. 
Hexagonal. The data from which the table was compiled were 
drawn from numerous sources, but especially from the following 
works: Gmelin’s Handbook of Chemistry, Graham’s Elements 
of Chemisiry, Phillips’s Mineralogy by Brooke and Miller, and 
Gustav Rose’s Krystallo-chemische Mineralsystem. References 
have been given only in a few cases, to avoid crowding the tables. 
For authorities in other cases, the author would refer to the above- 
mentioned works. 
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% e 
CoRRESPONDENCE. 
Extract from a letter from Dr. W. I. Burnett to Prof. J. D. Dana. 
Magnolia, Florida, March 1, 1854. 
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Frortpa still remains almost a terra incognita to naturalists, al- 
though in geological structure, and Fauna and Flora, one of the most 
interesting States in the Union. Even from the limited survey I have 
of its surface and general features, | am persuaded that some 
*rroneous views have been entertained as to its formation and the 
€xact nature of its peninsular relations. Naturalist after naturalist, 
from the time of the quaint old Bertram to the present day, have trav- 
®rsed its various sections, collecting specimens relating to their partic- 
War line of study, but no report has yet been made, {in full, of the 
* * 
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