614 
DK. A. GrAMGrEE ON THE ACTION OF NITEITES ON BLOOD. 
space remaining between the rim h and the tube, and thereafter slipping the caoutchouc 
cap g over the neck, and. wiring it at i and k. 
The exit-tube f is connected to a bulb b of the capacity of 100 cub. centims. ; this 
bulb is supported in the water-bath x along with the bottle a; it is connected with the 
bulb c , which rests in a separate tin vessel y containing cold water ; c is united to the 
IJ-tube d , and this is surrounded by cold water in the tin vessel z. The U-tube d is 
joined to the bulb e, which is connected to a very perfect Sprengel tube fixed in a firm 
wooden stand. The various tubes and bulbs are united with the aid of black tubing, 
melted india-rubber, and wire. Working with care there is no difficulty in getting this 
apparatus admirably tight. In my first experiments I made use of a more complicated 
Sprengel tube than the one figured in my diagram, i. e. one furnished with a gauge-tube 
on which a millimetre scale was etched, and which dipped into a vessel in which a very 
perfectly boiled barometer also dipped. In my later experiments I have used the sim- 
plest form of Sprengel tube, as I have found that the most satisfactory and perfect test 
consists in getting a perfectly unbroken column of mercury in the fall-tube, and observing 
that on allowing the mercury to flow after the apparatus has remained exhausted for 
some hours, not a particle of air can be removed. 
When the tightness of the apparatus has been ascertained, and it is desired to use 
it to extract the gases of blood, the water in the bath x is heated to about 100° Fahr., 
and the temperature kept as constant as possible by regulating the supply of gas to the 
burner which heats it. A small glass tube (see diagram representing the blood-recep- 
tacle, page 613), limn, having an internal diameter of a millimetre, bent at right angles at 
m, is filled with the blood to be analyzed. The end n is closed with the fore finger of the 
right hand, and with the aid of the other hand the end l of the tube is inserted into the 
end o of the india-rubber tube on bed, until its passage further is resisted by a clip at e. 
The finger may now be taken away from the end n, without any risk of the blood which 
it contains escaping. The india-rubber tube had, however, better be wired to the glass 
tube Imn , so as to remove all risks of air getting access to it. 
The blood to be analyzed is now placed in an accurately measured flask or bottle, and 
after its volume has been determined the vessel containing it is weighed. When this 
operation has been completed, the tube Imn, previously described, is plunged to the 
bottom of the flask containing the blood, and the clip e is cautiously opened ; the blood 
is sucked into the vacuum, and when enough has entered the clip is rapidly and firmly 
closed. The flask which contained the blood is now weighed ; after this, distilled water 
is allowed to flow out of an accurately graduated burette until the level of fluid in 
the flask is the same as it was before the blood was taken for analysis. The amount 
of distilled water poured out of the burette indicates the volume of the blood used. 
The blood which has thus been allowed to flow into the receptacle enters into violent 
ebullition; a tube filled with mercury has, of course, previously been placed in the 
pneumatic trough connected with the Sprengel tube, and now mercury is made to flow 
through the latter incessantly. In about six minutes from the time when the blood 
