[ 37 ° ] ' 
though the fame pieces of dyed linen were inftantly 
turned of a green colour, when expofed to the fumes 
of fpirit of hartfhorn. Whether therefore, and 
under what relations, this aereo-faline fpirit may- 
merit the title of an acid, I leave to the determina- 
tion of others. Such, however, it has appeared to 
be to many philofophers, fince this mephitic air is 
doubtlefs the fame with the acidirn vagum fodinarum 
of boerhaave and others; and with the acidum 
centrale perpetuum inexhauribile of becfier ; with 
the fpiritus fulpbureus aerec-cztherco-elajlicm of hofr- 
man ; and the J'al embrionatus and fal efurinm of 
the fagacious helmont, which,, he fays, corrodes 
the ore of iron, and with it forms a volatile vitriol 
in the pouhon water. All thefe, and many other 
philofophers, had acquired fome knowledge of this 
lubtile aereo-faline principle from contemplating its 
effedts ; but, not having obtained it in a palpable 
form, were unacquainted with fe.veral of its prin- 
cipal properties. 
From considering the great fubtility-of this aereo- 
faline principle, its power of diffolving many earthy 
fubftances, together with its property of uniting 
readily to water, and with it, ol pervading the vetv 
minute veflels of the animal frame, without injuring 
them, as flronger acids do by their corrofive quality, 
we may from thence form fome judgement of the 
great efficacy of this air, as a de-objiruent and folvait, 
in many difeafes of the human body arifmg from 
preternatural concretions and obftrudlions thence en~ 
fuing. If to thefe we add the great antifeptic 
powers of this kind of air, which it polleffes in com- 
mon 
