CHAP. IV.] THE BLOOD. METHODS OF RESEARCH. 207 



which may be learned by reference to systematic works on analysis. 

 Accordingly, the extensive subject of gas analysis will not be treated 

 of with any pretence to completeness, the reader being referred 

 to other sources for information on the subject. The analysis of 

 gases is best carried out either by the methods suggested by Bunsen l 

 or with the aid of the most ingenious and accurate methods devised 

 by Professor Frankland. 



? 



Description of the methods of Frankland for the analysis of gases. 



We quote the whole description of these methods from the 

 excellent account given by Professor Btirdon Sanderson 2 . 



Frankland 1 s " ^ tn a y iew to the analysis of the gases of drinking 



smaller appa- water, Frankland has introduced an apparatus of great 

 ratus for the simplicity (see Fig 46). the working of which will be readily 

 analysis of understood by the diagram. It consists of two parts, viz., 



gases by afo- a laboratory tube (k), in which the gas to be analysed is first 

 sorptiometric received, and a measuring apparatus, to which it can be trans- 

 ferred from the laboratory tube, in order that its volume may 

 be determined before and after each absorption. The measuring apparatus 

 .consists of two tubes (a, b), fixed vertically side by side in a stand, surrounded 

 by a chamber containing water (n). They communicate below both with 

 each other and (by the long flexible tube) with a mercury-holder (t), like that 

 of Alvergniat's pump. One of them can bo brought into communication by 

 the arm (y) with the laboratory tube; the other (b) is open at the top. A 

 scale of millimeters is engraved on it, the zero of which is opposite o. A 

 corresponding scale, starting from a zero at the same level, is engraved on 

 the measuring tube. The apparatus is filled with mercury by raising 

 the mercury-holder (t) to a sufficient height, the stop-cock (/) remaining 

 open; in doing which the surface of the mercury in t must not be more 

 than a few millimeters higher than the tap. As soon as mercury appears 

 at g, the stop-cock is closed. The next step is to fill the laboratory 

 tube. Having inverted it in the trough, which has been previously 

 raised to the proper height, the operator draws out most of the air by means 

 of a bent tube, the point of which rises to the top of the laboratory tube, 

 and shuts the stop-cock as soon as the mercury rises. The removal of the 

 air is completed by joining g and g' so as to connect the laboratory tube 

 with the measuring apparatus, and then causing the air contained in 

 the former to pass over into the latter, by depressing t. The stop-cock h 

 must now be closed and g and y' disconnected to allow of the expulsion of 

 the air from a. This having been accomplished, g and g' are again 

 brought together and carefully t-ecured. The whole apparatus is now full 

 of mercury ; as soon as it has been ascertained that the joint is air-tight at 

 all pressures, it is ready for use. Before proceeding further, however, 

 the measuring tube, which, as already stated, is graduated in millimetres 

 measured from an arbitrary zero line near the bottom, must be calibrated. 

 In other words, it must be ascertained as regards each principal mark of tho 



1 Bunsen's Gasometry, translated by Eoscoe. 



2 Handbook for the Physiological Laboratory, pp. 202 20f. 



