Correspondence of J. Nickles. 381 
pyrites, although some authors consider the magnetic pyrites a 
protosulphuret, an inference not sustained by analysis. The min- 
_ eral in appara afforded me . 
: i : : ° . : - 62°38 
Sulphur, : i: : : ‘ > 35°67 
Nickel, . : - ri ; “iis GAPOe 
Copper, ; ; . 4 : i trace 
Silica, : ° ; : - § O66 
Lime, 0-08 
98°91 
The formula Fe S requires Sulphur 36°36, Iron 63°64 = 100. 
Further remarks on this mineral will be found in the paper on 
meteorites. 
. Cuban. 
This variety of copper pyrites was first noticed by Breithaupt, 
as occurring among the copper ores of Cuba. Desiring to reéx- 
amine it, specimens were obtained from Prof. Booth; they were 
massive and not perfectly pure, furnishing an insoluble residue 
consisting of silica and oxyd of iron which are very probably 
combined. Its sp. grav. was 4180, and its composition— 
i 2. 3. 
‘ -« 92:2 
. “ 18°23 19:10 a 19°00 
Cope, 39°57 39°20 39°30 
Residue (silica and oxyd of iron), 4:23 
9° 99°13 
This seems to setae the formula already received, (agreeing 
with the analyses of Prof. Booth,) CuS+Fe? 8°, pyrites being 
Cu? S+Fe? S*= Sulphur 42:28, Copper 20°82, Iron 36-90. 


Arr. XL.—Correspondence of M. Jerome Nicklés, dated Paris, 
June 28, 1854. 
Academy of Sciences.—F'or some days, the Academy has been 
occupied repairing the loss experienced at the beginning of the 
year. In place of Dr. Roux, Dr. Claude Bernard has been named, 
well known for his discoveries in Physiology: in place of Admi- 
ral Roussin, an officer of the navy, M. Bravais, an admiral in 
Science, although but a lieutenant in his official capacity. The 
labors of M. Bravais have not been confined to na navigation and 
hydrography. He has published important mathematical works ; 
his researches on halos, auroras, mirage, the rainbow, parhelia, 
and meteorology in general, have given him a prominent name 
in Physics, while his works on the arrangement of leaves on 
the symmetry of inflorescence, the laws of growth of 
the oa sylvestris, have made him known to naturalists. 
