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air which has been lately made noxious. I have 

 even fpent feveral hours in pouring this air from one 

 glafs veffel into another, in water, fometimes as cold, 

 and fometimes as warm, as my hands could bear it, 

 and have fometimes alio wiped the veffels many 

 times, during the courfe of the experiment, in order 

 to take off that part of the noxious matter, which 

 might adhere to the glafs veffels, and which evi- 

 dently gave them an offenfive fmell ; but all thefe 

 methods were generally without any fenlible effect. 

 The motion, alfo, which the air received in thefe 

 circumftances, it is very evident, was of no ufe for this 

 purpofe. 



This kind of air is not reftored by being expofed to 

 the light, or by any other influence to which it is 

 expofed, when confined in a thin phial, in the open 

 air, for fome months. 



Among other experiments, I tried a great variety 

 of different effluvia, which are continually exhaling 

 into the air, efpecially of thofe fubftances which are 

 known to refiit putrefaction j but I could not by thefe 

 means effect any melioration of the noxious quality of 

 this kind of air. 



Having read, in the Memoirs of the Imperial So- 

 ciety, of a plague not afflicting a particular village, 

 in which there was a large fulphur work, I imme- 

 diately fumigated a quantity of this kind of air; or 

 (which will hereafter appear to be the very fame 

 thing) air tainted with putrefaction, with the fumes 

 of burning brimflone, but without any effect. 



I once imagined, that the nitrous acid in the air 

 might be the general reftorative which I was in 

 queft of; and the conjecture was favoured, by find- 

 ing 



f 



