Vital Air in the Atmofphere* 'Z^^ 



fulphuret, without being fhaken, keeping the apcrtUTcs un- 

 ftopped and immerfed in the fame liquid? eont-aincd in a 

 veflcl. Several other experiments gave me the fame refuUs. 



A fourth part of a meafure of common air, Ihakcn with five 

 nieafures or twenty times its voUime of fulphuret, loft o-a6. 

 I fuppofed that this fubflancc, except the 0*21 or 0*22 of 

 vital air, which compofed the atmofpheric air, had abforbed 

 dlfo o*5 of its mephitic air. 1 thence concluded, that if I 

 fliould Ihake another ecpal quantity of common air in the 

 fame fulphuret, which by the preceding manoeuvre I confi- 

 dered as already united with all the mephitic air it could take 

 up, it would not dccreafe more than from 0*21 to 0*23; and, 

 indeed, this was the refult. I immediately introduced an 

 equal quantity of mephitic air, which fuftained no lofs by 

 the agitation of the fame fulphuret, which muft have been 

 already impregnated with it. But on ihaking this mephitic 

 fiiir in a flaflc containing alfo five meafures of fulphuret, differ- 

 ing from the other only in this, that it had not been before 

 fliaken with any air, it loft 0*05 ; which is the difference of 

 21 and 26. It is therefore evident that fulphuret is capable 

 of containing a certain portion of mephitic air; and the 

 more it is deprived of it, the greater will be the abforption of 

 atmofpheric air. This fa6t was proved by the following ex- 

 periment: — I filled a flafk, capable of containing five mea- 

 fures, with fulphuret newly made, and ftill in a ftate of ebul- 

 lition, and which, confequently, was free from gafeous mat- 

 ter : and without giving it time to abforb any, I corked it 

 lip, and when it had cooled I introduced the fourth part of a 

 meafure of atmofpheric air, which being regularly fhaken 

 from three to five minutts, loft 0*50 ; that is to fay, one-half 

 of the whole. In this cafe then, befides the o*2i, it abforbed 

 0*29 of mephitic air ; and I really found this to be the cafe, 

 by trying one-founh of a meafure of mephitic air, which was 

 fhaken in the fame fiafk^ with frefh fulphuret, in every thing 

 fimilar to the former. The hundredths wanting between 

 29 and 50, which are 21, indicate the quaiuity of vital air 

 only which had difappeared in the proof of the atmofpheric 

 air» After this it may be eafily conceived that this air will 



decreafe 



