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Experiments on Factitious Air. 
PART I. 
Containing Experiments on Inflammable Air. 
I Know of only three metallicfubftances, namely, zinc, 
iron and tin, that generate inflammable airbyfolu- 
tion in acids ; and thofe only by l'olution in the diluted 
vitriolic acid, or fpirit of fait. 
Zinc diflolves with great rapidity in both thefe 
acids; and, unlefs they are very much diluted, generates 
a confiderable heat. One ounce of zinc produces about 
356 ounce meafures of air : the quantity feems juft the 
lame whichfoever of thefe acids it is diftolved in. Iron 
diflolves readily in the diluted vitriolic acid, but not near 
lb readily as zinc. One ounce of iron wire produces 
about 412 ounce meafures of air; the quantity was juft 
the lame, whether the oil of vitriol was diluted with 
14, or 7 times its weight of water : fo that the quan- 
tity of air produced feems not at all to depend on the 
ftrength of the acid. 
Iron diflolves but flowly in fpirit of fait while cold: 
with the afliftance of heat it diflolves moderately faft. 
The air produced thereby is inflammable ; but I have 
not tried how much it produces. 
Tin was found to diflolve fcarce at all in oil of 
vitriol diluted with an equal weight of water, while 
cold : with the afliftance of a moderate heat it diftolved 
ilowly, and generated air, which was inflammable : 
the quantity was not afcertained. 
Tin diflolves flowly in ftrong fpirit of fait while 
^old : with the afliftance of heat it diflolves moderately 
faft. 
