316 



THE HUMAN MOTOR 



the one as a manometer and the other for measuring the gas, 

 and communicate below by a curved portion, receiving water 

 from the vessel R. When R is raised, a three-way cock, r, allows 

 the gas contained in the glass bulb a to pass either into K or into 

 P (fig. 225). 



All the cocks being open, the reservoir R is raised by means of 

 the hand-wheel, MI, and air is driven through the tube r'i. The 

 cock, r', is then turned to open to s, the reservoir is lowered, and 

 the gases are drawn in through s, which is connected with the 

 spirometer or the test tube containing the gas (see fig. 221). 

 The water level is brought to zero on the graduation, on the lower 

 part of the apparatus, the whole capacity available for the gas 

 being then 100 cubic centimetres, of which 25 are represented by 

 the graduated tubeg. By closing r' and openings to the glass vessel 

 containing potash, the gas is driven into it and the solution is 

 driven out into B. The vessel R is lowered and raised to renew 

 the contact with the 

 solution. Meanwhile r" 

 has been closed. It is 

 opened at the moment 

 when, bringing the gas 

 to g, its volume is read 

 by the atmospheric 

 pressure, the level of 

 the water then being 

 the same in m and in g. 

 Let the reading be 3 

 cubic centimetres. That 

 means that 3% in vol- 

 ume has been absorbed 

 by the potash and repre- 

 sents the proportion of 

 carbonic gas. 



The same operation 

 is carried out with the 

 phosphorus, but the 

 gases are left there a 

 little longer. Let the 

 new reading be 20, then 

 the difference 20 3 = 

 17 represents the volume 

 absorbed by the phos- 

 phorus ; 17% is there- 

 fore the proportion of 

 oxygen. Let it be noted 

 that the graduated tubes 

 are immersed in a vessel 

 full of water, which re- FIG. 225. Laulanie's Eudiometer. 



