1340 



acid and alcohol, and evacuated with the waterjef pump, afterwards 

 with the carbon. 



When after the evacuation with the cocoannt carbon tap / was 

 closed, a gas pressnre again appeared in the apparatus after a short 

 time (Geissi-er tube H), and this was continually repealed. We shall 

 discuss the cause of this phenomenon later on. When the gas that 

 had generated in the apparatus, had been removed a few times, so 

 that it might i)e assumed that the apparatus did not contain any 

 more air, the mercury was transferred from E into B by tilting of 

 the lefthaud pari of the apparatus (the glass spring (t made, this 

 movement possible). The tap near (i was now closed, and the 

 apparatus was cut through between this tap and the glass spring ^z. 



The lefthaud part was connected by means of a rubber tube to 

 a manometer one meter long, foi- the higher pressures three meters 

 long. By a sucking pump, a taj» that allowed contact with the outer 

 air, and a tap that was connected with a cycle pump, the pressure 

 of the ail' between H and the manometers could be regulated at 

 will ill the measurements. Hence tube H acts as a cnt-otf valve 

 ill the determiiialious ; the difference of level in the manometer 

 corrected for the difference of position in l> yields the value of the 

 three-phase j)ressnre. In order to make it possible to determine the 

 difference of level in B a glass scale graduated in millimeters was 

 attached to the lube A* by the aid of cork disks and copper wire. 

 The determinations being carried out exclusively at temperatures 

 below room temperature, only bulb .1 was placed in a i>ath of 

 alcohol, which could be cooled down to definite temperatures by 

 addition of solid carbonic acid; a stirrer ensured uniform tempe- 

 rature in the alcohol bath. The cut-off valve B remained continually 

 in contact with the outer air. 



During the slow heating of the alcohol bath it now appeared that 

 already at low temperatures a rapid rise of pressure appeared, which 

 could not possibly be atti-ibnted to decomposition of the hydrate. When 

 the pressure had i-eached a definite value, the change with the tem- 

 perature had greatly diminished again. This fact pointed to this that 

 111 spite of the exhaustion with the cocoannt carbon the hydrate had 

 absorbed appreciable cpiantities of sulphuretted hydrogen, which were 

 liberated already at temperatures of about — 50° C 



The exhaustion with the cocaonut carbon had, accordingly, not 

 been sufïicient to remove the absorbed quantity of sulphuretted 

 hydrogen ; prolonged evacuation is, however, undesirable, because as 

 will appear later, the hydrate still possesses an appreciable tension 

 of dissociation at — 80° C, and decom|)osition must, accordingly 



