GENERAL DESCRIPTION OP RESPIRATION APPARATUS. 



59 



Fig. 28 shows the nature of the interior of the apparatus. The air 

 enters through one opening at the top, passes down through a bent pipe, 

 and enters a series of roses, consisting of inverted circular saucers with 

 holes in the rims. The position of the holes is such that when the vessel is 

 one-fourth to one-third full of sulphuric acid the air must pass through 

 the acid three times. To prevent spattering, a small cup-shaped arrange- 

 ment, provided with holes, is attached to the opening through which the air 

 passes out of the absorber, and for filling the vessel with acid a small open- 

 ing is made near one edge. The speci- 

 fications required that the apparatus 

 should be made absolutely air-tight to 

 pressures of over 1 meter of water, and 

 that there is no porosity in these vessels 

 under these conditions is shown by the 

 fact that such a pressure is held indefi- 

 nitely. The inside and outside are both 

 heavily glazed. There is no apparent 

 action of sulphuric acid on the vessels 

 and the slight increase in temperature 

 resulting from the absorption of water- 

 vapor as the air passes through does not 

 appear to have any deleterious effect. 



The vessels without filling and with- 

 out rubber elbows weigh 11.5 kilograms ; 

 with the special elbows and couplings 

 attached so as to enable them to be con- 

 nected with the ventilating air-system, 

 the empty absorbers weigh 13.4 kilo- 

 grams; and filled with sulphuric acid 

 they weigh 19 kilograms. Repeated 

 tests have shown that 5.5 kilograms of sulphuric acid will remove the water- 

 vapor from a current of air passing through the absorbers at the rate of 75 

 liters of air per minute, without letting any appreciable amount pass by 

 until 500 grams of water have been absorbed. At this degree of saturation 

 a small persistent amount of moisture escapes absorption in the acid and 

 consequently a second absorber will begin to gain in weight. Experiments 

 demonstrate that the first vessel can gain 1,500 grams of water before the 

 second gains 5 grams. As a matter of fact, it has been found more advan- 

 tageous to use but one absorber and have it refilled as soon as it has gained 

 400 grams, thus allowing a liberal factor of safety and no danger of loss of 

 water. 



FIG. 28. Cross-section of sulphuric-acid ab- 

 sorber. The air enters at the top of the 

 right-hand opening, descends to the bot- 

 tom of the absorber, and then passes 

 through three concentric rings, which are 

 covered with acid, and it finally passes out 

 at the left-hand opening. Beneath the left- 

 hand opening is a cup arrangement for pre- 

 venting the acid being carried mechanic- 

 ally out through the opening. The opening 

 for filling and emptying the absorber is 

 shown midway between the two large open- 

 ings. 



