411 



For determining tiie period of preheating therefore 7», is of practical 

 interest. 



The watervapour carried along from the vessel is combined in 

 (/, so thai dry air enters the l)ar_vla-tnlies. Tiie watervapour taken 

 from the lye is absorl)ed in J,. By measuring the increase of volume 

 in (/, il ma_y be found, how much waier disappears from the lye 

 and the titration standard may be corrected accordingly. This eva- 

 poration from the baryta-lubes is ver}' slight and amounled to circa 

 2 cc. in experiments lasting 3 days, so that the correction may be 

 left out without scruple. 



The manometer ?«, is tilled with mercury and seiwes to indicate 

 the pressure, to be surmounted liy the siu-king and forcing pump, 

 needed to drive the air through ilie vuiious liquids. A drop of 

 paraffine-oil on the mercury in ihe closed limb, prevents the origin- 

 ating of damaging mercury- vapouis. 



On Ihe rubber-pump /> taps a flat hammer //, moved verlicallv 

 by an electro-motor (not represenled in the tigure). This hammer 

 may lie mounted higher or lower in order to legulale the capacity 

 of the pumj) and consequently the size of llie bubbles. The speed 

 of the motor may be increased or ueci eased by means of a resistance, 

 with which the regulation of the number of bidibles is possible. 

 Size and number of bubbles are of course material to a good CO3- 

 absorption. 



For an eqiuible distribution of the air, entering the vessel, the 

 ebonite plates on which Ihe plants lie, are brought into a slow 

 rotary movement by an axis. Accumidalioii of C'O, in the vessel 

 (see further on) is excluded in this way. 



The suction of the air into and from the vessel, causes the liquid 

 in ///j to move up and down, which is not to be prevenled. At an 

 etfective regulation of the pump this movement may be kept so 

 slight, that it is no impediment. Indeed the motor may be stopped 

 at any moment, to convince oneself whether the manometer is really 

 at zero. 



The whole apparatus is tixed to the inside of a copper frame 

 and tits exactly in a glass vessel (contents about 45 L.), serving as 

 a water-thermostat. Electrical heating enables us to keep the tempe- 

 rature of the water constant to 0.03° C. The oscillations of tempe- 

 rature in the apparatus itself are slighter than those in the thermostat, 

 so that corrections relating to this, may be omitted. 



If the apparatus is immersed in the water of the thermostat, it 

 may be easily tested with respect to air-tightness. For this purpose 

 air is pumped into the apparatus through /,, and one watches whether 



27 



Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



