200 Continuation of the Experiments and Ohfervations 
without any eftervefcence ; and by this fame inflammable air 
is the copper evidently reduced, acquiring fplendor, malleabi- 
lity, and every other metallic property. But if the folution 
o'f copper be not faturated with copper, a fmall quantity of 
inflammable air may be caught, as the excefs of acid will dif- 
engage more of :it from the iron than the calx of copper can 
take up. Inflammable air , is then the principle that metallizes 
metallic earth.; and if .metals . contain only a fpecific earth and 
phlogifton, inflammable air certainly contains nothing eife but 
phlogifton. If iron and the arfenical acid be^digefted together, 
no inflammable air is produced ; but the arfenical acid is, in 
great mealure, converted into white arfeuic, as Mr. b&rg- 
man .has obferved, and alfo Mr. scheele* ; what reafon can 
be afligned why inflammable air is not produced by this as Well 
as by all other acids ^ but that this metallic acid received it, 
and was by it reduced to a femi-metallic form, as by pure phlo- 
gifton ? Yet this acid produces inflammable air, from zinc be- 
caufe zinc gives out more phlogifton than the regulus of arfe- 
nic can take up ; but it attra&s and is metallized by a part of it, 
and it is only the excefs that appears in the form of inflammable 
air, as Mr. scheele has remarked. This inflammable air, indeed, 
is not pure, for it holds fome of the regulus in folution ; but 
this portion of regulus does not enter into its compofition, as 
is very evident. 
Thirdly, Inflammable air is the fubftance which, with vitri- 
olic acid, forms fulphur, for it is the very fubftance which the 
vitriolic acid feparates from metals ; and this fubftance, lo fepa- 
rated, when in fufficient quantity, and in proper circumftances, 
unites to it in fiich proportion as to form common lulphur. 
Thus fulphur is formed by diddling concentrated vitriolic acid 
* 2 Nov. A tt. Upfal. p. 310. Kw, Veten. Accad. Handlingar, vol. 36. p. 28S. 
with 
