112 NATURAL SCIENCE. August, 1895. 



iron, alumina, copper, lead, molybdenum ; also sulphates, chlorides, 

 phosphates, vanadates, carbonates, silicates and titanates, and found 

 traces of lithium, tellurium, and fluorine. 



Professor Tait has contributed two valuable Reports bearing on 

 Ocean Physics. The first of these is on the pressure error of the 

 " Challenger" thermometers. In view of the high pressure existing 

 at great depths, a correction of at least half a degree Fahr. for every 

 mile under the sea had been assigned to the thermometers, although 

 protected. This was considered by Professor Tait to be excessive, 

 and he proceeded to investigate the matter and found that pressure 

 alone can affect the reading of the thermometers when let down into 

 the sea, and that in no case does the correction exceed one-seventh of 

 a degree per mile of depth. Other experimenters had been misled 

 in their laboratory experiments by the heating effect due to sudden 

 compression. 



The above Report gave rise to a number of interesting questions 

 bearing on Ocean Physics, which were subsequently investigated 

 and formed the basis of his Report on some of the Physical Properties 

 of Water. This includes the investigation of the compressibility at 

 high pressures of fresh and sea-water, of solutions of common salt, and 

 of glass and mercury ; it also takes up associated physical questions 

 such as the change of temperature produced by compression, the 

 internal pressure of a liquid, and others. 



Both these papers involved a great amount of experimental work 

 and contain much that is of permanent value to pure physics. 



A. Ritchie Scott. 



