292 Dr. H. Will on M. Reiset’s Remarks 
hydrate of soda, and must be kept in a state of fusion with it 
for many hours before the oxidation is complete. 
Reiset states that ammonia is disengaged by heating me- 
tallic iron and potash-ley to 292° Fahr., with access of air, 
but not so in an atmosphere of nitrogen. This statement 
rests on a very equivocal foundation. Pure iron can be 
heated for a long time in a boiling potash-ley without the dis- 
engagement of hydrogen; the oxidation takes place only on 
the fusion of the alkaline hydrates. Ifa quantity of potash-ley 
which has stood for a long time in a perfectly clean retort be 
heated, there is always observed at the commencement a slight 
disengagement of ammonia, but this soon ceases altogether. 
The, by no means inconsiderable, quantities of ammonia 
obtained by Reiset, admit of no other explanation than that 
his mixture of soda and lime contained a nitrate, probably ni- 
trate of potash, which, as Faraday states, easily evolves am- 
monia when the smallest trace of it is melted with zinc and 
an alkaline hydrate. If Reiset had only, in a small degree, 
followed or observed the extremely cautious and cir¢umspect 
manner of proceeding of that celebrated English philosopher, 
a manner which is with justice admired by him, he would not 
have endeavoured to find sources of error in a method‘ to 
which, on this point at least, no very weighty objection can be 
made. 
The nitrate of potash contained in the soda-lime used by 
Reiset, was very probably owing to the circumstance that most 
manufacturers add alittle of it to the commercial hydrates of 
soda and potash, for the purpose of improving their appear- 
ance. In Reiset’s experiment, where he obtained 4°8 per 
cent. too much nitrogen in chincovatina, his mixture must have 
contained very nearly 3 per cent. of nitrate of potash, when it 
is considered that his tube contained from 50 to 60 grammes. 
This also explains in a much simpler and easier manner the 
formation of ammonia in an atmosphere of hydrogen, and also 
the limited increase of ammonia from the increased quantities 
of sugar employed. Asthe whole quantity of nitrate of potash 
would be destroyed by from 1 to 11 gramme of sugar, the 
quantity ‘of ammonia could not increase. The nitrogen was 
here certainly contained in such a condensed state, that a 
stream of hydrogen gas passed over it during twelve hours 
did not expel it. 
I now come to the second source of error objected, by 
M. Reiset, to the new method. It appears from his statements, 
that a part of the chloride of platinum is reduced to proto- 
chloride when the hydrochloric acid fluid, which in many 
cases contains liquid hydro-carburets, is evaporated to dry- 
