J. M. Ordway on Nitrates of Iron. 317 
nitrous gas and nitrogen.” “In the beginning of a dissolution 
the nitrous gas generally predominates, in the middle nitrous 
oxyd, and at the end nitrogen.” 
It should be remembered that the terms cron and nitric acid 
in mutual contact. A sound philosophy would therefore at the’ 
outset suggest the inquiry whether the action of nitric acid on 
iron is not a function of several variables, such as the quality, 
the quantity, and the strength of the acid; the form, the kind, 
the state, and the amount of iron, and the quantity put in ata 
ime; the initial temperature, and the range of temperature 
allowed during the action, pressure, light, rest or agitation, and 
of air. 
aving only the data afforded by a few hundred experiments, 
I cannot presume to enter into a systematic and thorough dis- 
phuric acid. The following are the final approximating terms 
of convergent series of experiments made by varying the tem- 
peratures, all other things being equal : 
1, V.—At 45° C., 100 g. of nitric acid of sp. gr. 1-03, with 5 g. of iron 
added all at once, gave off hydrogen continuously. The temperature 
during the action rose to 49° 
n—At 46° C., the same 
wy 
2 AA 
