'264 Chemical Instruments and Operations, 



Fig. 1. 



The receiver, fi«r. 2, shaped hke the small end of an egg, 

 is employed in these experiments, being mounted so as to 

 shde up and down upon a wire. 



Fig. 2. 



This receiver being filled 

 with water, and immersed 

 in the pneumatic cistern, 

 the apex. A, being just 

 even with the surface of 

 the water, by drawing out 

 the rod of the eudiometer, 

 take into the tube one 

 hundred measures of at- 

 : mospheric air, and transfer 

 it to the receiver. jVext 

 take fifty measures of nitric oxide from a bell as above de- 

 scribed, and add it to the air in the receiver, without allow- 

 ing the gas to have any contact with the water, which is not 

 inevitable. Wash the mixture by a jet of water, which is 

 easily produced from the apex of the instrument, and draw 

 the whole of the residual gas into the tube, continuing to 

 draw out the rod until one hundred and fifty graduations ap- 

 pear. In the next place, eject the residual gas from the in- 

 strument ; the number of graduations of the rod which re- 

 main on the outside of the tube, shows the deficit produced 

 by the absorption of the oxygen, and nitric oxide, in the 

 state of nitrous acid. 



In a great number of experiments, I have found the deficit 

 to agree very nearly with that produced by the explosion of 

 the same quantity of air with hydrogen in the aqueous slid- 

 ing rod hydro-oxygen eudiometer. 



