Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

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$when it gives up its gases to the vacuum. The blood immediately Iroths u[) and loses its bright red colour, becoming of a dark claret tint. Fill the tube or eudiometer {h) with mercur}'^ and insert it over b. By turning the tap T into the position (3), on lowering B the blood gases pass into Aa, on turning the tap into the position (2) and raising B the gases ai'e forced into and collected in h. The escape of the gases from the blood is greatly facilitated by placii;g the bulb R in warm water ms shown in the figure ; and, moreover, the escape of watery vapour helps to carry over the gases more rapidly into Aa. In some forms of the instru- ment a drying-vessel contain- ing pumice stone and sulphuric acid is introduced between Ji and T. The joints of the appa- ratus are surrounded with caps of caoutchouc, which are filled with mercury when the appa- ratus is in use ; thus any leak- age at a joint is detected at once.] Mayow (1670) observed that gases were given off from blood in vacuo. Magnus (1837) in- vestigated the percentage com- position of the blood gases. The more important recent in- vestigations have been made by Lothar Meyer (1857), and by the pupils of C. Ludwig and E. Pflüger. 35. aiTANTITATIVE ESTIMATION OF THE BLOOD GASES. — The gases obtained from blood consist of 0, COg, and N. Pflüger obtained (at 0° C. and 760 mm. Hg pressure) in round numbers about 60 vols, per cent, from the arterial blood of a dog (large artery) and from venous blood (right side of heart). As is shown in figs. 29 (J) and 30, the gases are collected in an eudiometer, i.e., in a narrow tube, closed at one end, and with a very exact scale marked on it, and having two fine platinum wires melted into its upper end, with their free ends projecting into the tube (jp and n). (1) Estimation of the COg.—A small ball of fused caustic potash, fixed on a platinum wire, is introduced into the mixture of gases through the lower end of the eudiometer under cover of the mercury. The surface of the potash ball is moistened before it is introduced. The COg unites with the potash to form potassium carbonate. Tho potash bulb is withdrawn after 24 hours. The diminution in volume indicates the amount of CO2 absorbed. (2) Estimation of the 0.—(a) Just as in estimating the COg, a ball of phosphorus on a platinum wire_ is introduced into the eudiometer ; it absorbs the 0 and forms phosphoric acid. Another plan is to employ a small papier-mache ball saturated with pyrogallic acid in caustic potash, which rapidly absorbs 0. After the ball is removed, the diminution in volume indicates the quantity of 0. {h) The 0 is most easily and accurately estimated by exploding it in the eudiometer. Intro- duce a sufficient quantity of H into the eudiometer, and accurately ascertain its volume ; an electrical spark is now passed between the wires, p and n, through the mixture of gases ; the 0 4 Fig. 31. Scheme of Alvergniat's gas-pump. R, receptacle for blood ; t, thick tube with tap communicating with it; A and B, bulbs for mercury ; a, barometer tubing ; M, windlass ; P, pulley ; T, tap ; g, connecting-tube to R ; c, cup for mer- cury ; h, eudiometer ; II, 1, 2, 3, positions that can be given to the three-way stop-cock or tap T. I, Small part of c and T enlarged to show the eudiometer.$