J. M. Ordway on Nitrates of Iron. 
“ acid heated to 42° C. rapidly dissolved iron wire. 
8, «.—A pale commercial acid of sp. gr. 1-40, warmed to 83° C., re- 
fused to dissolve iron wire, 
ith such acid at 34° C., the action kept o 
6.—Some pure acid redistilled with pedocaate of potash, having the 
sp. gr. 1°40, and being warmed to 36°C., quickly induced passivity in 
iron wire. 
With some bes ve same acid at 37° C., the action did not cease till the 
‘iron was all 
c.—Pure rok ‘acid of sp. gr. 1:40 warmed to 58°C., rendered wire 
ssive. 
Such — at 59° C. continued to ac 
me commercial red acid of st gr. 1:40 warmed to 65° C., had 
but a Ebgmianeaae se effect on iron wire, i 
he same acid at 66° C., kept on acting. Ber 
9.—A pale acid of sp. gr. 1-41 hea ted to 41°C, , rapidly dissolved 
en this same ei ~ risky shaken at the time of contact, 49° 
C. was the limit of pas 
20, a.—Pale acid of ie oe 1:42, at 55° C., rendered iron wire passive ; 
at 56° C. the action kept on on. 
b.—Common red nitric acid of sp. gr. 1-42, even when warmed to 82° 
C., at ey in iron; but with the same acid at 83°, the action 
eeu 
. 1:30, heated to 50° a wh 
1° there was a continued gen 
- Other acid - sp. gr. 1°30 with other sorts of steel, gave the 
ait of passivi 
22. ja Pte nitric acid of sp. gr. 1:34 heated to 71° C., soon ceased to 
act on steel wire; when such acid was first heated to 72° it did not in- 
duce passi vity. 
6.—The same acid even at 100° C.. = no action on the same steel 
‘Wire freshly annealed and scoured brigh 
s ten steel, two very long turnings 
were broken up, and furnished bits Lee = a large number r of experi- 
- seis uts wit ay al of one and the same qua 
23.—On tl 1s steel nitric acid of sp. gr. : ‘38 acted Tapidly and contin- 
en it had been ape cooled to 0° C, ie 
rr. 1°27 and at 40°C. soon ce Sas to act on a bit. vs 
risk ‘etaton: with the acid first heated to 40° 
ds fap. gr. 1-28, 1-29, 1-32, 1:33 and 1-34, the limit of 
e and 40°C, 
| 345 ae at 52°8° C., the steel became passive; 
ted to 53°3°, the pearte went mae 
en at 76-7° C. rendered the steel passive; when 
to 795° the action waite not stop. 
re also tried with c common red titre aide 
