li)l Dr. T. Thomson on the Geology and Climate of Nice. 



The variation in the quantity of rain which falls at Glasgow and its 

 neighbourhood is not less remarkable. The annual fall in the College 

 Garden, according to a register kept by the late Dr. Couper, Professor of 

 Astronomy, averages 21*331 inches. A register was kept with great care 

 for several years of the fall of rain at Greenock, by the late Mr. James 

 Leitch, from which it appeared that the fall in Greenock was very nearly 

 double that in Glasgow. The mean fall at Stocky Muir, only about 

 twelve miles distant, is 42- 6 inches, or double the fall in Glasgow. 



Snow falls at Nice once in four or five years. We had it last winter 

 to the depth of half an inch. In places screened from the sun it lay three 

 days, but where the sun acted on it, it melted in a few hours. 



In the year 1837 the fall of snow at Nice was the greatest ever known. 

 It lay to the depth of six inches. 



About a century ago, it was the universal opinion that when sea water 

 was evaporated the vapour carried with it a portion of the salt, and there- 

 fore that fresh water could not be obtained by distilling sea water. 



Vogel and some other chemists examined the air over the Baltic, and 

 found it to contain common salt. And the late Dr. Dal ton observed the 

 panes of his windows in Manchester incrusted with common salt after a 

 violent storm of wind and rain. From these and similar observations, it 

 has been pretty generally supposed that the atmosphere over the sea, and 

 in its neighbourhood, contains common salt in solution. The question 

 was decided some years ago at Nice by M. Brunner, Professor of Chemis- 

 try at Berne, and M. Roubodi of Nice. 



A large globular glass vessel, filled with a mixture of snow and sulphuric 

 acid, was suspended a few feet above the ground, and six paces distant from 

 the sea, when the sea was calm and no wind was blowing. Abundance 

 of aqueous vapours were collected and condensed on the outside of the 

 vessel, and a colourless liquid was collected exactly similar in appearance 

 to distilled water. After being kept for six months, its appearance was 

 not altered. When evaporated to dryness it left no residue. It was not 

 precipitated by nitrate of silver nor nitrate of mercury, and therefore con- 

 tained no muriatic acid nor common salt. Chloride of barium occasioned 

 no precipitate, showing that sulphuric acid was not present. The absence 

 of lime was indicated by oxalate of ammonia, occasioning no muddiness 

 when dropt into it. 



With solutions of barytes and lime it became slightly nebulous, and 

 after some hours a very slight deposit fell, soluble in nitric acid. These 

 phenomena indicate the presence of a trace of carbonic acid. 



This experiment was repeated when the sea was in a state of agitation, 

 great waves dashing impetuously against the beach. When the liquid 

 collected was tried by reagents, the results were very different. 



Nitrate of silver made the liquid opal, and after some hours a precipi- 

 tate fell possessing all the characters of chloride of silver, thus showing 

 the presence of chlorine in the liquid. 



In like manner nitrate of mercury formed white clouds in it, which pre- 

 cipitated to the bottom. 



