Origin of Masses of Tin Ore. 159 
We remember that about twenty years ago M. de Buch 
ascribed this latter effect to finorine, to account for the decom- 
position into kaolin of certain porphyries in the neighbourhood 
of Halle, in Saxony ; but M. Daubrée is the first who has as- 
signed to this simple substance a power which may be said to 
be creative. 
The intervention of fluorine in the formation of the oxide of 
tin is in accordance with the greater part of the circumstances 
which accompany these metalliferous deposits. At the same 
time this ingenious theory is not free from all objection. M. 
Daubrée announces, at the end of his memoir, that he is en- 
gaged with researches in the laboratory which will throw light 
on this important subject. 
Your commissioners hope that the details into which they 
have entered regarding M. Daubrée’s memoir, will prove to 
you, that, independently of the ingenious theoretical considera- 
tions to which it leads, the work contains a great number of 
carefully observed facts, and new and judicious applications 
of them. 
They consequently propose to you that thanks should be 
returned to this young professor for his interesting communi- 
cation, and that he should be invited to continue the researches 
he has commenced on the action of fluorine in the formation 
of metallic deposits. They likewise ask of you to vote for the 
memoir being printed in the collection of the Savants Etran- 
gers, if the means of publication have not been already pro- 
vided in the Annales des Mines. 
The conclusions of this report were adopted.* 
Account of the Belemnites of the Lower Cretaceous Formations 
in the neighbourhood of Castellane. By M. Duvat-Jovuve, as 
reported on by the French Academy of Sciences. 
Beremnites, which abound in a fossil state in secondary 
formations, and which owe their name to the rude resem- 
blance they bear to a dart or arrow, have, for a long time, 
* From Comptes Rendus, No. 17, 25th October 1841, p, 854. 
