354 T. S. Hunt—Chemieal and Geological 
writer in 1858. In 1862, however, there was opened a sealed 
acket which had been in 1844 deposited by Cordier with the 
rench Academy of Sciences, and was found to contain views 
as to the origin of limestones and of sea-salt similar to those 
just stated.* Thus, in the preseut state of our knowledge we 
conclude that all carbonates of lime, whether directly formed 
by the decay of calcareous silicates, or indirectly through the 
intervention of carbonates of magnesia or alkalies, derive their 
carbonic dioxide from the atmosphere. The same must be said 
* Hunt, Chem. and Geol. Essays, pp. 2 and 20. F 
+ These considerations, and their stratigraphical bearings, first set forth n 
1863 (Chem, and Geol. Essays, pp. 27 and 28), will be found further developed in 
i 2 
ter’s report on Azoic Rocks, 2d Geol. Survey of Penn., 1878, p. 10. be 
+ 
