214 Intelligence and Miscellanies. 



beneficial effect of his exertions and example will remain to 

 distant generations.* 



Foreign extracts^ hy Prof. J. Griscom. 



24. Carbonic Acid of the Atmosphere. — A memoir on this 

 subject, by Theodore De Saussure, read before the Helvetic 

 society, in June, 1828, contains some interesting facts. The 

 author determined the amount of carbonic acid in a given 

 portion of air at any one time, by enclosing barytic water in 

 a large glass balloon, full of the air to be examined, and as- 

 certaining the weight of the carbonate formed. The por- 

 tion of carbonic acid, he observes, is undergoing almost con- 

 tinual changes. The mean quantity as determined by ex- 

 periments commenced in June, 1816, and continued to 1828, 

 in a meadow at Chambeisy, near Geneva, is, at mid-day 4.9 

 parts in 10,000 of air. The maximum was 6.2; the mini- 

 mum 3.7. 



The mean quantity of carbonic acid in the atmosphere is 

 greater in summer than in winter. The author finds that 

 the relative proportions are as 100 to 77. 



There are occasional exceptions to this difference. In the 

 month of January, 1828, which was extraordinary for the 

 mildness of its temperature, the quantity of carbonic acid 

 rose to 5.1. In the month of August following,! remarka- 

 ble for its being singularly cold and rainy, the quantity at 

 mid-day, the mean of four observations, was only 4.45. 



The author finds that there is an increase of carbonic acid 

 during the night. The mean of 9 results, obtained at mid- 

 day, is 5.04, and of corresponding observations at 11 in the 

 evening, 5.76. 



A comparison of the air over the middle of Lake Leman, 

 with that at 200 yards from the shore, showed a slight differ- 

 ence. The quantity over the land being to that over the 

 water, as 100 to 98.5 The air of Geneva was found to con- 

 tain more than that of the country, in proportion of 100 to 

 92, by simultaneous observations in the two places. 



* For a just and affectionate notice of Dr. Smith's character, see the Chris- 

 tian Spectator for March, 1829; some traits of character not peculiarly appro- 

 priate to this Journal, are there noticed. 



t These experiments were made after the reading of the memoir before the 

 Helvetic society. 



