Intelligence and Miscellaneous Articles. 301 



avoided placing the metal in immediate contact with the condenser, 

 putting a very thin plate of ivory between them. 



M. Delarive has also announced an important fact. He has ascer- 

 tained that the transmission of electricity from one conductor to an- 

 other varies sensibly, according to the direction of the current ; that is 

 to say, for example, that positive electricity passes more readily from 

 copper to zinc, than from zinc to copper. The discovery of this fact 

 serves to explain many phenomena hitherto regarded as anomalous. 

 The author states that lie was led to this discovery by the obser- 

 vations of M. Fourier relative to the passage of heat through sub- 

 stances according to the order in which they are arranged. — Le Globe, 

 June 30, 1830. 



ATMOSPHERIC CARBONIC ACID. 



M. Thdod. De Saussure has made numerous experiments to deter- 

 mine the variations of carbonic acid in the atmosphere, and published 

 them in the memoirs of the Physical and Natural History Society of 

 Geneva. The following results are extracted from the Bibliotheque 

 Universelle for June 1830. 



The carbonic acid was absorbed by barytes water, and the carbo- 

 nate precipitated was estimated to contain 22 per cent, of carbonic 

 acid. The experiments were made at Chambeisy, about three quar- 

 ters of a league distant from Geneva, and 16 metres above the level 

 of the lake; 10,000 volumes of air contain 4*15 of carbonic acid, as 

 the mean of 104 experiments made day and night and at all seasons 

 of the year; the air was taken four feet above the ground ; the great- 

 est quantity of carbonic acid was 5*74, and the smallest 3*15. 



An increased quantity of rain appears to diminish that of the car- 

 bonic acid, either by dissolving it or in causing the soil to do so ; a 

 litre of fresh rain-water, which did not render lime-water turbid, gave 

 in summer, by an hour's boiling, 20*5 cubic centimetres of air, which 

 contained 13 - 46 of azote, 673 of oxygen, and 0'31 of carbonic acid : 

 and it appears from a very elaborate set of experiments, that the quan- 

 tity of carbonic acid is generally larger as that of the rain is smaller ; 

 — thus in June 1827, the quantity of rain was 9 millimetres, and that 

 of the carbonic acid 5- 1 8, in 10,000 of air; while in September 1829, 

 the rain was 254 millimetres, and the carbonic acid only 3"57 volumes 

 in 10,000 of air. 



It was found that during the night the quantity of carbonic acid 

 was greater than that of the day in the proportion of 4°32 .to 3*98 ; 

 but if the wind be strong, then scarcely any difference occurs. The 

 greater quantity of carbonic acid occurring in the night is attributed 

 to the want of decomposition which occurs by vegetation during the 

 day. 



A short frost and which does not penetrate the earth to more than an 

 inch, does not appear to cause any variation in the quantity of carbonic 

 acid ; but when the frost continues long, the dryness which it occa- 

 sions increases the proportion. In the beginning of January 1829, 

 the ground was lightly covered with snow, and the quantity of carbonic 

 acid increased to 4 57; towards the end of the month it thawed for 



several 



