C. ELECTEICITY, LIGHT, HEAT, AND SOUND. 47 



BLUE COLOR OF LAKE AND SEA WATER. 



Professor Tyndall has recently been investigating the cause 

 of the blue color of the water of the Lake of Geneva, speci- 

 mens having been transmitted to him for the purpose. He 

 finds that this color is caused, as had previously been sug- 

 gested, by the presence of small mineral particles, probably 

 derived from glacier dust (brought into the lake by drain- 

 age from glacier streams), of such extreme minuteness as not 

 to settle even when the water is allowed to stand for a Ion 

 time. Professor Tyndall furthermore states that not only is 

 the light mainly blue from the first moment of its reflection 

 from the minute particles, tout the less refrangible elements 

 which always accompany the blue are still further abstract- 

 ed during the transmission of the scattered light by true 

 molecular absorption. These two causes, scattering and ab- 

 sorption, he considers sufficient to account satisfactorily for 

 the exceptional blueness of both the Lake of Geneva and of 

 the Mediterranean Sea. 12 A, October 20, 487. 



BOILING POINT OF UNMISCIBLE LIQUIDS. 



Mr. Kundt announces in Pogro-endorff's "Annalen" that 

 where two liquids having different boiling points are brought 

 together, that do not combine w T ith each other, as, for exam- 

 ple, water and benzole, water and oil of cloves, water and 

 sulphide of carbon, etc., they will boil at a lower tempera- 

 ture than when the more volatile of these liquids is brought 

 to ebullition by itself. This fact may be placed side by side 

 with that lately published, that a liquid having a boiling 

 point higher than that of water can be brought to boil by 

 steam applied through pipes in a suitable manner. 1 A, 

 October 14,191. 



ACOUSTIC PHENOMENA ON MOUNT SINAI. 



Captain Palmer gave an account to the British Association 

 of a remarkable acoustic phenomenon on a certain mountain 

 in the peninsula of Mount Sinai, from which loud and myste- 

 rious noises are frequently known to proceed. This mountain 

 is a peculiar sand-slope, about two hundred feet high, and 

 nearly triangular in shape, eighty yards wide at the base, 

 narrowing toward the top, where it runs off into three or four 



