File:An American text-book of physiology (1897) (14760261276).jpg

Identifier: americantextbook00howe (find matches)
Title: An American text-book of physiology
Year: 1897 (1890s)
Authors: Howell, William H. (William Henry), 1860-1945 Bowditch, H. P. (Henry Pickering), 1840-1911
Subjects: Physiology
Publisher: Philadelphia : Saunders
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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bulb Bli is raised the mercuryrises in the tube AC and fills B,driving the air out by the pathFHOP, the stopcock Q being closed.When Bb is lowered again the mer-cury flows back from B into Bb,creating a Torricellian vacuum inB. As soon as the mercury hasfallen below the joint D, thisvacuum in B becomes connectedby the path DEG with the tubesTGIJGT and the tube VWYX, andthence, when the stopcock is open,with the vessel to be exhausted. The air in this then diffuses to fill thevacuum in B, and becomes rarefied, so that the mercury rises from the cylin-ders SR and SR in the outer tubes TG and TG. The small inner tubesRG and RG are made so high that even when there is a complete vacuum inthe outer tubes TG and TG the mercury will not rise high enough to coverthem. On raising Bb again the mercury rises in AC, and as soon as the joint D is.covered, all the air which has been caught in B is forced out by the path FHOP.Each time the bulb Bb is raised and lowered a certain amount of air is ex-
Text Appearing After Image:
FiG. 136.—Kemps gas pump. BESPIRA TION. 529 tracted from the receiver, until finally a vacuum is produced. In a similarway, when the receiver connected with the pump at Z contains any gas whichwe wish to analyze—as, for example, the gases given off by the blood in avacuum—we put a eudiometer (Eii) over the bend of the tube at P, which, ofcourse, is always under the mercury, and collect the gases as they are forced out. The extraction of the last traces of gas by raising and lowering Bh is avery tedious and laborious process, so that the final extraction of the gases canbest be accomplished by the Sprengel jnimp LTKLMNIIOP. The bulb and stop-cock UK are made separate, as shown in the figure, and are connected withLMN by a piece of rubber tubing, the whole being under mercury. This isaccomplished by the bend JKLM, which is made so as to allow a narrow woodenbox filled with the mercury to be slipped up over the bend high enough tocover the stopcock and thus prevent leakage of air.

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