

330 Determining Moisture and Carbonic Acid in Air, 



linity after the experiment. There were, however, several 

 reasons for doubting whether this was really due to escape 

 of carbonic acid through the soda-lime. We therefore made 

 the following experiment. 



A current of air, after passing through sulphuric acid and 

 soda-lime absorption-tubes, was divided by means of T-tubes, 

 and passed through six Pettenkofer tubes placed beside one 

 another on a board. The loss of moisture from the baryta- 

 water in these tubes was determined by means of a sulphuric 

 acid absorption-tube placed in the air-current beyond them. 

 The moisture which had collected in the tubing connecting 

 the Pettenkofer tubes and this absorption-flask was washed 

 into the flask by means of a current of dried air. 60 litres 

 of air were aspirated in one hour. 



In addition to the six Pettenkofer tubes through which the 

 air was passed six others were taken, and charged with the 

 same quantity of baryta solution in exactly the same way as 

 the first set. These dummy tubes were kept stoppered 

 during the experiment. 



All the tubes were washed before the experiment, first 

 with dilute nitric acid, then three times with tap- water, and 

 finally with distilled water. At the end of the experiment 

 the baryta from each set of tubes was poured into a small 

 flask, and at once corked and allowed to stand for a time. 

 During these manipulations every precaution was taken to 

 avoid unnecessary contact of the baryta-water with air. The 

 results are given in full. 



Sulphuric acid, pair 1. -f- 0*41 83. 

 Soda-liine, pair 1. +00554. 



Baryta-water from C (1) 40 c. c. = 39*9 c.c. standard oxalic, 

 first set of Petten-< 

 kofer tubes. ((2) „ = 39*9 „ „ „ 



Loss of water from same tubes by evaporation 0*8408 gram. 



Baryta-water from C (1) 40 c. c. = 39*65 c. c. standard oxalic, 

 dummy set of Pet-< 

 tenkofer tubes. (.(2) „ = 39*75 „ „ „ 



Mean . . 39*7 



Standard baryta-water 40 c. c. =40*25 standard oxalic. 



Therefore 

 loss of alkalinity in 1st set = 6 x 0*35 = 2*1 c. c. standard oxalic 

 and loss by evaporation = 0*84 „ „ 



lossof alkalinity in 2ndset = 6 x 0*55 = 3*3 „ „ 



