58 
PROFESSOR W. RAMSAY AYD DR. M. 5Y. TRAVERS 
Fig. 4. 
h 
delivered into the intake of the low-pressure purifier A, the same air was returned 
into the compressor ; the amount which had been liquefied was replaced by ordinary 
air, drawn into the purifier, and from it to the compressor, at the same time. In 
this manner the air which passed through the liquefier was fractionated and 
refractionated, for the heavier and more condensable portions were continually 
removed, wlfile tlie lighter portions passed again through the machine. The escape 
valve, Q, at the top of the liquefier (fig. 1) was connected l)y thick-walled india-rubber 
tubing with the bull) a (fig. 4) immersed in a vacuum-jacket which was fiUed with 
the liquid air continually being produced during the process; that is, with the 
portion which had condensed from the total quantity entering the machine. The 
lioiling point of this liquid air was unusually low, for it contained, owing to the 
process of circulation, a larger proportion of nitrogen than usual. The air entering 
the hull) a was under an additional pressure of about an atmosphere and a half, as 
shown by a gauge. When the bulb a was filled with licpiid to near the top, the 
stop-cock h was shut, so that the compressed 
air no longer freely entered the bulb, 
but passed through the narrow tube c, and 
l)ubbled through the liquid in the bulb. 
0)1 opening the stop-cock c/, which commu¬ 
nicated with a tube leadino' to a laro;e o-as- 
holder, the liquid in the bulb evaporated ; 
when about one-sixth had boiled off into 
the gasholder, this part of the operation 
was stopped; and by shutting the stop¬ 
cocks h and r/, and opening the clip e, the 
liquid in the Imlh was forced out, and flowed 
into the outside jacket, increasing the 
volume of air employed for the purpose of 
condensation. In this manner, the mis- 
holder, of about 120 litres capacity, was 
filled with the liglitest and lowest-boiling 
portion of liquid air. In case others may 
desire to repeat this operation, a word 
of caution may be o-iven : it is absolutely 
I/ O */ 
necessary to blow air thi’ough the contents 
of the liquefying bull), while eyaporation is 
proceeding ; if this is not done, eyaporation 
takes place chiefly from the surface, and 
the e;as collected in the gasholder will con- 
tain yery little neon ; it was oidy after 
*/ 
seyeral unsuccessful trials that we dis- 
