193 
Figure 125. Upper part of the measuring 
burette in Fingerling’s carbon-dioxide sampling 
device. 
(r) Platinum wire contact which conducts the 
current by means of the mercury in p 
(q) Valve for the air entrance 
(o) Vajve for the air exit 
(s) Safety contact in case r does not work, 
s is shunted to a relay which takes the entire 
current when s comes in contact with the mercury. 
At the same time it gives an alarm. 
Ventilation construction