30 



DR. R. ANGUS SMITH ON THE 



winter, or vice versa. Thus after many years of observa- 

 tion, the mean quantity of carbonic acid in the month of 

 January in io_,ooo of air is 4*23 ; but the quantity of car- 

 bonic acid in the month of January 1828, which was ex- 

 traordinary for the mildness of its temperature, rises to 5*1. 

 The average quantity of carbonic acid in the month of 

 August, taken in different years, is 5*68; but after an 

 average taken from four observations (the results of which 

 closely approximate) in the month of August 1828, which 

 was singularly cold and wet, the quantity of carbonic acid 

 at noon was only 4*45. 



" The difference in the quantities of carbonic acid con- 

 tained in the atmosphere in calm weather, during day and 

 night, is one of the most remarkable results of my late 

 observations. The following is the table of experiments 

 which I have made, in open country, at noon and at eleven 

 o'clock in the evening of the same day. (The Table in 

 the original gives the quantities of carbonic acid in 10,000 

 parts, but for uniformity's sake they are here altered into 

 percentages.) 





Noon. 



Evening, 

 II o'clock. 



May 22nd, 1827 



July 7th, „ 



Sept. 3rd, „ 



Nov. 6th, „ 



May 31st, 1828 



■0581 



.058 



•0561 



•043 



•0475 



•0506 



•0539 

 •0432 

 •0429 



•0623 



•062 



■0601 



•0486 



•0565 



•0583 



•0522 



•0606 



•0582 



June 1 3th, „ 



June 26th, ,, 



Aug. ist, ,, 



Aug. 12th, ,, 





" It results from these observations, that the air contains 

 in calm weather more carbonic acid during the night than 

 during the day. The only exception to this result was on 

 June 26th, 1828, during extremely violent wind, whilst all 

 the other observations were made in calm weather or in 

 slightly disturbed air. I have acquired sufficient experi- 



