400 Eudiometer. < [Book V. 



perfectly fwect; the firft quite firm, the flefh of the 

 fecond flill foft, but not in the leaft putrid. From thefe 

 experiments Dr. Prieftley recommends nitrous air as 

 an antifeptic. Unfortunately, however, though ani- 

 mal fubftances may be preferved from putrefaction for 

 feveral months by nitrous gas, yet they become dry, 

 diftorted, and ofTenfive to the palate, fo as to render 

 the difcovery of little public utility. 



5th. The fpecific gravity of nitrous air is to that of 

 the atmofphereas 1195^0 1000. 



6th. One of the moft remarkable properties of this 

 air is, that it condenfes or dlminifhcs in bulk with oxy- 

 gen or dephlogifticated air, by which means it becomes 

 a teft with rcfpect to the quantity of that pure element 

 contained in the atmofphere. With pure dephlogifti- 

 cated air the diminution is almoft to nothing, at the 

 fame time that nitrous acid in fome quantity is repro- 

 duced by the condenfation of the nitrous air j but as the 

 air of our atmofphere is always mixed with a confider- 

 able quantity of azotic or phlogifticated air, on which 

 nitrous air has no effect, the diminution in this cafe is 

 never fo confiderable. Upon this principle the eudio- 

 meter for meafuring the purity of air is formed. 



To underfland the nature of this inflrument, let a 

 glafs tube (Fig. 4.) of about nine inches long, clofed at 

 One end, and of about three-fourths of an inch diameter, 

 be filled with and inverted in water; then take a phial 

 of about half an ounce meafure, filled with common air> 

 and plunging it under the water contained in the fame 

 bafon with the inverted tube, let that quantity of air 

 enter into the tube j it will then rife to the top of the 

 tube while the water fublldes. Let a mark be made 

 on the tube at the height of the water in it, to (how 

 how much of the tube is filled by that meafure of air. 

 In the fame manner inject four or five me^fures of com- 

 mon. 



