PLATE XXXIV 
Fig. i.—Balance for weighing oxygen cylinder and end view of absorber table: 
A, Cylinder containing oxygen tinder pressure; B, empty cylinder for counterpoise; 
C, valve for reducing pressure of oxygen from cylinder; D, rubber bag to collect sample 
of air for determination of residual oxygen; E, meter for measuring sample of air for 
determination of residual moisture and carbon dioxid; F, pipe for air returning to 
chamber; 6, pipe for air coming from chamber; H, valve for closing circulating air 
system between absorbers and ingoing air pipe; /, trap for removal of sulphuric-acid 
spray from returning air; K, point at which air from meter is restored to air returning 
to chamber. 
Fig. 2.—Method of attaching heating and cooling systems to zinc wall: A, Hooks of 
iron wire, screwed into metal framework, supporting brass pipe for cooling zinc wall; 
B y porcelain insulators, carrying resistance wire for heating zinc wall; C, exterior ends 
of wooden supports of thermoelements projecting from zinc wall; D , wooden strip, 
dividing air space adjacent to zinc side walls into upper and lower zones. 
