40 GASEOUS METABOLISM OF INFANTS. 



f-inch size (approximately 16 mm. internal diameter). The couplings 

 are therefore interchangeable with different forms of apparatus. With 

 a standard rubber hose gasket, the couplings can be made air-tight by 

 a simple twist of the hand. All of the piping throughout the apparatus 

 is of standard |-inch (16 mm. internal diameter) galvanized iron pipe. 



Two-way valve. — In order to deflect the main air-current from one 

 set of purifiers to the other, it is necessary to have a 2-way valve, but 

 unfortunately this can not be purchased in the open market. For this 

 purpose we have taken an ordinary 3-way |-inch gas cock and soldered 

 up one of the ports, then ground it again to fit the valve body. When 

 properly done and the valve lubricated with a little cerate or vaseline, 

 the result is very satisfactory. The valves V x and V 2 are of this type. 

 A long steel rod connects these two valves so that by throwing the 

 handle at one valve both valves are simultaneously closed and the 

 air-current instantly deflected from one set of purifiers to the other. 



Soda lime and containers. — The most effective absorbent for carbon 

 dioxide that we have found is slightly moist soda lime. So important 

 is the preparation of this reagent that we consider it fitting to republish 

 the method here. 



The soda lime is prepared in a round-bottom iron kettle, holding 

 about 3 liters. For this purpose 1,000 grams of commercial caustic 

 soda of good quality are dissolved in approximately 600 c.c. of water. 

 When completely dissolved, 1,000 grams of finely pulverized quicklime 

 are rapidly stirred into the hot lye and the stirring continued with a 

 long-handled iron rod. The lime is immediately slaked, a large amount 

 of heat and steam being given off. If the operation is carried on out 

 of doors or under a good hood, soda lime may be readily made by 

 unskilled labor. 



For infants and for animals weighing not less than 3 to 5 kilograms 

 the ordinary soda-lime containers are used (Z>i and D 2 ), these being 

 wide-mouthed glass reagent bottles of the usual type. Each bottle 

 contains 2 kilograms of soda lime, capable of absorbing not less than 

 75 grams of carbon dioxide, and weighs when filled about 4 kilograms. 

 The moisture in the soda lime is essential to its efficiency, but the air 

 after passing through the absorbent must again be dried by passing it 

 through the Williams bottles E x or E 2 . 



Sodium-bicarbonate can. — In order to absorb the traces of acid fumes 

 which may remain in the air after it has been carried through the 

 Williams bottles, it is necessary to insert in the air-circuit a small can 

 filled with dry sodium bicarbonate (F). This completely removes the 

 acid fumes and does not affect the determination of the carbon dioxide 

 or of the oxygen in any way. 



Air-moistener. — With very small infants and with a fairly rapid flow 

 of air, it is quite possible that the humidity inside the chamber may be 

 too low for comfort and hence it is advisable to secure some means for 



