ELASTIC FLUIDS. 281 



what a priori, I had conceived ; for, according to my hy- Nitrous gas 

 polhefis, every gas diifufes ilfelf equably through any given ^J^^^^'^ys^eno^^^^^^ 

 ipace that may be alligned to it, and no other gas being in drogenoui, an'd 

 its w^ ay can prevent, though it may confiderably regard this"'^'^^' 

 difiufion. But in fome of the following experiments, in which 

 the two gafes are known to have a chemical affinity for each 

 other, I expeded different refults from what are found ; per- 

 haps without fufficient r^afon. For, chemical union cannot 

 take place till the particles are brought into contiguity ; and 

 the elaftic force which fets them in motion appears, from the 

 above experiments, to be a principle diametrically oppofife 

 to affinity. That circulation of elaflic fluids, therefore, 

 which we have now before us, cannot be accslerated by their 

 having a chemical affinity for each other. Another circum- 

 flance deferves explanation; — when nitrous and oxygenous 

 gas are in the two phials, the reliduary gafes after the ex- 

 periment are nearly as pure as before; becaufe thofe portions 

 of them that meet in the tube, form nitrous acid vapour, 

 wfiich is abforbed by the moitiure in the phials, and therefore 

 does not contaminate either gas. 



]. Two one ounce phials were connected with the fmall 

 tube, the under containing nitrous gas, the upper atmofpheric 

 air ; afier three hours, the upper phial was taken off when 

 a quantity of air was perceived to enter, as was expefled ; 

 the air in the upper phial was fcarcely diftinguifliable from 

 what it was at firft; that in the under phial was ftill fo much 

 nitrous as to require its own bulk of common air to fatu- 

 ra(G it. 



2. The above experiment was repeated, and the upper 

 pHial drawn off when the whole was under water, in order 

 to prevent communication with the atmofphere : about -J of 

 an ounce of water entered the phials, to compenfate the 

 diminution. Remaining air in the upper phial was a very 

 little worfe than common air, it being of the ftandard 1,47 

 when the former was 1,44. The gas in the under phial was 

 ftill nitrous and nearly of the fame purity as at firft ; for three 

 parts of it required four of atmofpheric air to fatura,te 

 ihem. 



3. Nitrous gas and one y oxygenous were tried in the fame 

 way : after four hours, the apparatus was taken down under 

 water. The upper phial was f- filled with water, and the 



gas 



