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VIII. Experiments on the Pressure of the Sea, at considerable 

 Depths. By Jacob Green, M.D. Professor of Chemistry 

 in Jefferson Medical College, Philadelphia, United States, 

 North America.* 



A MONG the various expedients resorted to for the purpose 

 ■*** of relieving the tedium and monotony of a sea- voyage, no 

 one is more common during a calm, than to attach to a long 

 line (the log) an empty bottle, well corked, and then to sink 

 it many fathoms in the sea. In all such experiments it is well 

 known, that the bottles upon being drawn up are either full 

 or are partially filled with water. The manner in which the 

 water gets into the bottle is in some instances perfectly obvious, 

 but in others very perplexing, if not wholly inexplicable. 

 Sometimes the cork, however well secured and sealed, is 

 driven into the bottle, and when drawn up the vessel is of 

 course found filled with water ; and in such cases, what is a 

 little surprising, the cork is often found occupying its ori- 

 ginal position in the neck of the vessel, being forced there no 

 doubt by the expansion of the dense sea-water on being 

 drawn near the surface. This seems to be proved by the 

 cork often being in an inverted position. In the above experi- 

 ment, and in some others to be mentioned presently, the bot- 

 tle appears to be filled instantly ; as the person who lowers 

 the bottle down often feels a sudden increase of weight, some- 

 what similar to the sensation produced when a fish takes the 

 hook on a dipsey line. 



Sometimes the above experiment is varied by filling a ves- 

 sel with fresh water, which on examination is found to be 

 replaced by salt water; the cork remaining apparently un- 

 disturbed. 



Sometimes when the previously empty bottle is only half- 

 full of water, this when poured into a tumbler effervesces like 

 water highly charged with carbonic acid gas. This is readily 

 explained : for when the bottle descends it is full of air, and 

 when the water enters, it will of course absorb the air ; espe- 

 cially when the dense water itself expands as it is drawn to- 

 wards the surface. 



Sometimes the experiment is performed by first corking the 

 bottle tight, and then tying over the cork a number of layers 

 of linen dipped in a warm mixture of tar and wax ; in fact, 

 every device seems to have been tried to prevent the entrance 

 pf the water by the cork. In many of these cases, when the 



* Communicated by the Author. 



bottle 



