rilAKMACOLOGICAL USES OF ARTIFICIAL CIliCULATIOX. 2G0 

 Fig. 131. 



JW~U 



A and C, Bottles containing mercury or water, b, Wooden blocks, by wliicb 

 A may be raised to the required height. If water be used, it is easier to suspend 

 it from a pulley in the ceiling, so as to get sufficient pressure, d is a manometer, 

 to estimate the pressure in c and e. e is a bottle containing blood, r is n, small 

 stand to raise the bottle e from the bottom of g, as it is otherwis'? apt to become 

 too warm, and tlie bottom of the bottle cracks, or the blood is decomposed. G, a- 

 tin water-bath. At one side of it is a trougli with hollow sides, into which the- 

 warm water freely pass3s, and in which the organ to be experimented on may be 

 laid. H is an iron stand supporting G. J is a Mitscherlich's burner, k is a 

 thermometer, by which the temperature of the water-batli is examined- 

 L, Bunsen's gas regulator, as modified by Gcissler. This apparatus consists of a. 

 wide glass tube, w, divided into two parts by a septum, from the middle of 

 which a tube runs down nearly to the end of w. The upper part is filled with 

 mercury, which, of course, runs down the inner tube and fills the bottom of w, 

 compressing the air in it. A perforated cork, z, is then put into the upper part 

 of w, and the tube Y pushed through the hole in its centre. Inside T, and 

 shorter than it, is a second tube x, and the two are sealed to one another at their 

 upper ends. The tube y is then connected to a gas-pipe, and x to Mitscherlich's 

 burner, by india-rubber tubing. So long as Y is not pushed so deeply into "W 

 that the point of x dips into the mercury, the gas enters through Y, passes down 

 between y and x, comes up again through x, and goes to the burner. The 

 apparatus is now set by dipping it into the water-bath, and heating the water to 

 98°, or any other temperature desired, and then pushing Y down till the point of 

 x is just covered by the mercury. The passage of gas through it is at once 

 stopped, and the flame would go out were it not that a very small hole in the 

 side of x admits just enough gas to keep it alive. As the flame gets low, the 

 temperature of the water-bath above it diminishes, the air and mercury in "W 

 contract and leave the end of x open, so that the gas again passes freely to the 

 burner, and the flame becomes larger. The water-bath now regains its former 

 temperature, the air and mercury expand, the end of x is again closed, and 

 again the flame becomes small. By this apparatus a water-bath may be kept for 

 a very long time without varying more than half a degree. 



test. We can analyse the blood flowing into, and that flowing 

 from, the substance of the organs before and after the experi- 



