ON THI QUANTITY OF CARBON IN CARBONIC ACIIT. 219 



constantly ascertained by the eudiometer before every expe- whioh its puri- 

 , ;, , , • . , • ty wasascci- 



nrnont, and was generally determined in about 10 minutes. ta ined. 

 The solution employed was that recotnmendt d by Professor 

 Davy ; namely, the solution of green sulphate of iron satu- 

 rated with nitrous gas*; and whenever the diminution had 

 arrived at its maximum, and the gas began to increase in 

 volume, we substituted a. simple solution ofj the green sul- 

 phate of iron for that saturated with nitrous gas, and always 

 had the most satisfactory results : for the simple sulphate 

 absorbs any nitrous gas which may have escaped from the 

 saturated solution, and the residuum in this case enables us 

 to ascertain exactly the quantity of oxigen contained in the 

 gas. 



We determined to make our first experiment with char- Woods char 

 coal, and as Morozzo and Rouppe had ascertained the ab- re ' 

 sorbing properties of this substance, and as our results must 

 obviously be influenced by it, our attention was directed to 

 this point. The following quantities of different kinds of 

 wood, sawed into slips -tV of an inch were weighed. 



White Fir 300 grains ° Their weight. 



Lignum Vitas 800 



Box • 400 



Beech • • • • 500 



English Oak 250 . 



Mahogany ...... o(,o 



These slips were put into small crucibles, and completely j n sma n cruc i_ 

 covered with dry sand. Heat was very gradually applied at ble * u »der dry 

 first, until the volatile parts were dissipated ; they were then 

 kept about 40 minutes iu a white heat. On being collected 

 and weighed, while still warm, the charcoal from each was as 

 follows : 



fir 51*5 grs, equal to 18-17 per cent. Weight of 



Lignum Yitae 138 17-35 . duced** ^°" 



Box 81 20-25 



Beech • 75 15 



Oak 43-5 17'40 



Mahogany. 31'5 ••• 1575 



* Tnis solution absorbs oxigen much more rapidly in warm weather 

 than in cold. 



These 



