318 J. M. Ordway on Nitrates of Iron. 
m.—At 17°C., 50 g. of acid and 3 g. of turnings gave off hydrogen for 
a moment, then stopped entirely, and then went on and evolved nitric 
oxyd to the end. ; 
5, V.—Taking another kind of iron turnings, at 29° C. 60 g. of nitric 
acid of sp. gr. 1:04 and 3 g. of iron gave hydrogen and a protonitrate. 
n.— At 30° C., the same quantities of the same materials gave hydro- 
gen for a while, and then changing evolved nitric oxyd and made a per- 
nitrate. 
floating in the water over which it was caught. The gas was 
found to be capable of discoloring paper moistened with a lead 
_ solution. So a small fractional per-centage of sulphur is the 
_ chief, if not the only, constituent of iron which suffices to make 
1 
probably it is the proportion of sulphur which determines for 
acl a d 
tween hydrogen and nitric oxyd production. I have seen 4 
temporary evolution of hydrogen even with an acid of sp. gr 
1°08, and i 
$) Bt. 1:04, with two parts 
rogen at first and then evolved nitric oxyd and 
ts of nitric acid of sp. gr. 1-04, with 28 parts — 
ie eve OYGrogen only and made a protonitrate. 
__* Bxperiments and Observations on Different Kinds of Air; London, 1779, iii, 19% 
