[BER 14. I9l8] 



NATURE 



-07 



sphere. Consequently the Research Committee in 

 orl advocates the complete abolition oi such 

 in favour of the mouthpie< e. With a "fa< e-mask 

 or "hall-mask," the injectoi principle, oi having 

 .1 good artificial flow oi air always passing the 

 mouth, is essential. Otherwise an excessive 

 amount of carbon dioxide soon accumulates in 

 the mask, with the resull thai the efficiency "I 

 the wearei is seriousl) affected. Various other 

 minor advantages have been claimed for the in- 

 jector type, hut ii has so many dangerous draw- 

 backs thai the Research Committee strongly advo- 

 cates the complete abolition of the injector in any 

 i us. 

 All the main types of apparatus, with their 

 advantages and defects, are discussed at length in 



working, almost unbearable. The trouble, how- 

 1 ver, with the average cartridge that has been put 

 on the market in the past is thai it has been 

 totally inadequate to perform the work claimed 

 for it by the makers, and in consequence lives 

 have in many cases been endangered by the use 

 of such apparatus. 



To give an example of an apparatus coming 

 under 'lass 2 i.e. where the oxygen supply is 

 derived from liquid air- the description of the 

 " Aerophor " may he quoted from the report. 

 There are quite a number of these apparatus in 

 use in the United Kingdom, and with further 

 research and improvement they should be capable 

 of doing very good work. The "Aerophor" is 

 show n in Figs. 5 and 6. 



the report. The difference in method of purifica- 

 tion of the expired air may be referred to briefly 

 here. In the case of most compressed oxygen 

 apparatus the purification is effected by passing 

 through a metal cartridge or purifier containing 

 granulated soda, potash, or both. The expired 

 air thus passes through the purifier before reach- 

 ing the breathing-bag. Considerable heat is 

 developed by the action of carbon dioxide and 

 moisture upon the regenerating agent, and in the 

 case oi tbi " I'roto " apparatus, in which the 

 alkali is actually contained in the breathing-bag 

 itself, the heat produced is not easily dissipated, 

 owing to the non-conducting character of the 

 rubber bag. The temperature of the inspiratory 

 air becomes then, under certain conditions of 

 1559, VOL. I02] 



The receptacle A, holding the charge of 8 lb. or 

 10 lb. of liquid air (which in practice always con- 

 tains more than 00 per cent, of oxygen), is carried 

 together with the purifier U on the wearer's back, 

 while the breathing-bag 15 is at the front. To 

 prevent the wearer being affected by the extreme 

 cold of the pack, the canvas jacket which sup- 

 ports the apparatus is padded at the back with 

 felt, and an air-space is left between the padding 

 and the pack'. At the Northumberland and Dur- 

 ham stations the half-mask is employed, while at 

 the Rotherham station — where the accompanying 

 photographs were taken — the mouthpiece is used. 

 The absorbent material within the metal receptacle 

 is asbestos wool. To charge the apparatus liquid 

 air is poured in from a laree Dewar storage bottle 



