[ 2o 5 1 



perfectly agreeable to the analogy of Dr. Mac- 

 bride's difcoveries, and may naturally be expected 

 from them, that it mould have fuch an effect. 



By a mixture of fixed air I have made whole- 

 fome the refiduum of air generated by putrefac- 

 tion only, from mice plunged in water. This r „ 

 one would imagine, £ priori, to be the moft nox- 

 ious of all kinds of air. For if common air only 

 tainted with putrefaction be fo deadly, much more 

 might one expect that air to be fb, which was ge- 

 nerated from putrefaction only ; but it feems to be 

 nothing more than common air tainted with pu- 

 trefaction, and therefore requires no other procefs 

 to fweeten it. In this cafe, however, we feem to 

 have an inftance of the generation of genuine com- 

 mon air, though mixed with fbmething that is 

 foreign to it. Perhaps the refiduum of fixed air 

 may be another inftance of the fame nature. 



Fixed air is equally diffufed through the whole 

 mafs of any quantity of putrid air with which it is 

 mixed; for dividing the mixture into two. equal 

 pjarts, they were reduced in the fame proportion 

 by pairing through water. But this is alio the cafe 

 with fbrrie of the kinds of air which will not incor- 

 porate, as inflammable air, and air in which brim- 

 ftone has burned. 



If fixed air tend to correct air which has been 

 injured by animal reipiration or putrefaction, lime- 

 kilns, which difcharge great quantities of fixed air^ 

 may be wholefbme in the neighbourhood of popu- 

 lous cities,, the atmofphere of which mud abound' 

 with putrid effluvia.. I lhould think alfo that phy- 

 fieians might avail themfelves of the application 



