Practice of Kinetics (Comprehensive Chemical Kinetics, Volume 1)

3 APPARATUS 313.2.4 Analytical section ($ow and static systems)This section usually contains traps, sample bulbs, a gas burette and an automaticTopler pump or a Sprengel pump. The latter is rarely used nowadays. Two typesof automatic Topler pumps are shown in Fig.23. One of them combines aMcLeod gauge and Topler pump for the accurate measurement of pressures ofsmall quantities of gases1Og. Three tungsten contacts in conjunction with the mercuryin the pump connected to the circuit (Fig. 24a) operate a solenoid valve whichis connected from the Topler pump to either air or vacuum, thus allowing gasesto be pumped over to the gas burette. An alternative circuit shown in Fig. 24bincorporates a photoelectric device'". This avoids the problem of fitting and possiblesparking of tungsten electrodes, particularly when explosive gases are used.The products and undecomposed reactants may be separated from one anotherby low temperature distillation using various slush baths" ', produced from variousliquids and liquid nitrogen (see Table 3). It is important to maintain these- Gas-collectingcapillaryReferences pp. 104-111rig. ~ 5 Auromaric . iopier pumps. (01 is irom rer. IUY.