by Carbon Dioxide. © 191 
of CO, required. It was to test the validity of this method, 
(which however is of little practical value, since it is only appli- 
view of the fact that the absorption in the first layers of a gas 
1s greater than in the subsequent ones. In the case of Co, 
however, we have a very different state of things. Here we 
as great an effect. 
he experiments of Dr. Heinrich Heine* are much more con- 
clusive. By measuring with a delicate form of manometer 
the increase of pressure of the enclosed gas due to warming by 
the absorbed radiant lieat from a Bunsen burner, he found that 
while perfectly dry pure air produced no change whatever, the 
admixture of 025 per cent of CO, produced a readily measur- 
able increase, so that he was able to make very accurate analy- 
ses of the air by comparing its effect (after drying) with that of 
mixtures of known proportions. He did not however experi- 
* Ueber die Absorption der Wiirme durch Gase, und eine darauf beruhende 
se 
Methode zur Bestimmung des Kohlensiuregehaltes der atmospharischen Luft. 
‘Giessen, 1882, 
