THE RESPIRATION APPARATUS. 29 



Six of these soda-lime cans are always on the absorber-system table, 

 three of them connected ready for use. The same form of coupling, 

 *. e., that shown at right of figure 13, is used throughout the whole 

 absorber system, i. e., on the water-absorber cans and on the valves 

 at both ends of the absorber system. The cans not in use are closed 

 at both ends with rubber stoppers and all extra cans are placed on 

 a rack fastened to the wall. (See fig. i.) 



Removal of spent soda lime from the can. After an absorber has be- 

 come exhausted, i. <?., when no further increase in weight is observed, 

 the can is placed in the vise and the collar started one or two turns of 

 the thread by means of the clamp. The can is then carried to some 

 convenient place, the collar unscrewed with the hand, and the top 

 removed. When the can is inverted the soda lime generally slips out 

 of the can without any difficulty. The spent soda lime is of much 

 lighter color than the fresh, and is usually found to have agglomerated 

 into the form of cakes such as are shown at the right of figure 12. To 

 insure the free removal of the spent soda liine the cans are occasionally 

 given a thorough washing. 



Preparation of soda lime. The use of a partially moist soda lime for 

 the absorption of carbon dioxide seems to have been first adopted by 

 Haldane 1 ; but as our method of preparing soda lime is markedly dif- 

 ferent from that used by Haldane, and tests that we have made indi- 

 cate that its efficiency as an absorbing agent is considerably greater than 

 that of the earlier preparation, a description of the method of its prepa- 

 ration is given herewith. 



One kilogram of commercial caustic soda, preferably in the form of 

 fine powder, is dissolved in 750 cc. of water in an iron dish. We have 

 found a round-bottomed iron kettle admirably adapted to this pur- 

 pose. When the caustic soda has all dissolved, or by stirring with an 

 iron poker can be held in suspension, and while the liquid is still hot 

 from the action of the soda and water, one kilogram of pulverized 

 fresh quicklime is poured into the solution with constant and rapid 

 stirring. The lime should all be added before the expiration of 10 

 seconds. The stirring should be continuous and the lime held in sus- 

 pension as much as possible. In a few seconds the lime begins to 

 slack in the soda solution and the mass in the iron dish becomes very 

 hot, large quantities of steam escaping. Care should be taken to 

 avoid the spattering of drops of hot alkali. Rubber gloves should be 

 worn, and the operation conducted in a well-ventilated room or in the 

 open air. 



'Journ. Physiol. (1892), 13, p. 422. 



