THE RESPIRATION APPARATUS. 25 



Recourse was then had to earthenware absorbers, the parts of which, 

 by means of heav} r glazing, could be tightly joined together. This 

 type of absorber, while by no means all that could be desired, has given 

 fair results and is still in use. 1 The external appearance of the water 

 absorber is shown at the right in figure 1 1 . 



The absorber is 300 mm. high, 285 mm. in diameter, and contains 

 about 14.5 liters. There are three openings in the top two 40 mm. 

 in diameter for the entrance and exit of the air current, and a smaller 

 one of 15 mm., which is used for emptying and recharging the absorber 

 with acid. When the absorber is in use this opening is closed by a 

 well-vaselined rubber stopper, and the larger openings are connected 

 by couplings to the remainder of the absorber system. For convenience 

 handles are put on each side of the absorber, each being perforated in 

 the center to admit of the attachment of hooks for supporting the 

 absorber during weighing. Each can is numbered with enamel paint. 



The interior construction of the absorber is shown at the left in 

 figure 1 1 . The tube through which the air enters extends nearly to 

 the bottom of the can and has four openings or slots in its lower edge. 

 A circular disk not seen in the figure, 160 mm. in diameter, having a 

 rim 30 mm. deep, with a large number of holes in its edge, is fastened 

 30 mm. above the lower end of the extension tube. A larger disk 

 240 mm. in diameter, having a still deeper rim also provided with holes 

 in its periphery, is attached to the central tube 35 mm. above the first 

 disk. Acid is poured into the can until the whole flaring end of the 

 extension tube is immersed in acid, about 5.5 kg. being sufficient for 

 this purpose. Air descending through the entrance tube first passes 

 through the four openings in the end of the tube and, bubbling through 

 the acid, collects under the first disk ; it then passes out through the 

 small holes in the periphery and, bubbling through sulphuric acid the 

 second time, enters the second chamber, where it collects under the 

 second or larger disk. It then passes through the openings in the edge 

 of the larger disk and bubbles a third time through the acid to the sur- 

 face, whence it escapes through the second large opening in the top of 

 the can. To prevent spattering and escape of acid fumes through this 

 opening it is protected by a perforated earthenware cup filled with a 

 layer of pumice stone and a layer of asbestos. A thimble of wire gauze 

 is then fitted into the opening to prevent any of this material from 

 sifting out when the can is turned over, as in emptying. 



It is thus seen that the air bubbles through acid three times, and as 

 the bubbles are subdivided by the holes in the periphery of the disks, the 



1 We are indebted to the Charles Graham Chemical Pottery Works of Brooklyn, 

 New York, for much assistance in obtaining these absorbers. 



