GASES OF THE BLOOD. 



759 



H 



made when Ludwig and Setschenow, 1 Pfliiger 2 and Helmholtz, 3 constructed 

 their mercurial gas-pumps, based upon the principle of the Torricellian vacuum. 



The mercurial gas-pump. Numerous forms 4 of this apparatus have been 

 introduced, but here it is only necessary to mention Pfliiger's pump, the 

 modification of this made by Grehant, 5 and the simple apparatus devised by 

 Leonard Hill. The principle of the first is shown in the diagram on p. 758. 



Further details upon the construction and working of these pumps will 

 be found in text-books of physiological chemistry. 6 



In Leonard Hill's 7 gas-pump, the chief advantages are simplicity, cheap- 

 ness, and rapidity of action ; 

 the working errors are under 

 1 per cent., and only small 

 quantities of blood are required. 

 The construction of the pump 

 is shown in Fig. 70, and 

 the successive manipulations 

 are as follows : " A blood- 

 receiver (F) is affixed to the 

 end of the tube E, and the 

 receiver is elevated into the 

 position indicated by the dotted 

 outline. The reservoir (B) is 

 then put in connection with 

 the tube (E) by means of the 

 three-way tap (D), the reservoir 

 (A) is raised above the pump, 

 and the whole system is filled 

 with mercury to the top of the 

 blood-receiver (F). The screw- 

 clip on the rubber tube at the 

 upper end of F is then closed, 

 and the reservoir (A) lowered 

 until the blood-receiver is ex- 

 hausted, except for 2 or 3 c.c. 

 of mercury, which is purposely 

 left within. The screw-clip on 

 the lower end of F is next closed, 

 and the blood-receiver now 

 clipped at either end, exhausted, 

 detached from tube E, and 

 weighed. A sample of blood is 

 then collected. The arterial or 

 venous cannula is filled with 

 blood, and immediately afterwards pushed into the rubber tube at the 



i-Sitzungsb. d. k. Akad. d. Wissensch. Math-phys. CL, Wien, 1859, Bd. xxxvi. S. 293. 



2 " Untersuch. a. d. Bonner physiol. Lab.," 1865, S. 188; Centralbl. f. d. med. 

 Wissensch., Berlin, 1866, S. 305 ; Arch. f. d. ges. Physiol., Bonn, 1868, Bd. i. S. 61. 



3 See Zuntz, Hermann's "Handbuch," Bd. iv. Th. 2, S. 27. 



4 A. Schmidt, Ber. d. k. sachs. Gesellsch. d. Wissensch. Math-phys. CL, Leipzig, 1867, 

 Bd. xix. S. 33 ; Hoppe-Seyler, "Physiol. Chem.," Berlin, 1879, Bd. iii. S. 491 ; Nawrocki, 



*-v. iv -i 7 -r TT -i T"^__ T>J ^^ Ct T A A . T>,,^"U /< M ,.7, -f ^7 ^ -. Oi,.n/."7 



FIG. 70. Leonard Hill's Gas-Pump. 



"La pression barome'trique," Paris, 1878, p. 615. 



6 Halliburton, "Text-Book of Chemical Physiology and Pathology," London, 1891, p. 

 30; Hempel, " Gasanalytische Methoden;" Gamgee, "Physiological Chemistry of the 

 Animal Body," vol. i. pp. 200-206. 



7 Journ. Physiol., Cambridge and London, 1894-5, vol. xvii. p. 353 ; Hill and Nabarro, 

 ibid., 1895, vol. xviii. p. 218. 



