on the new method for the estimation of Nitrogen, §c. 293 
ness with it in a water-bath; consequently too much nitrogen 
must always be obtained, as this protochloride of platinum is 
insoluble in ether and alcohol. And this source of error has 
the more injurious effects on the result the more its necessary 
conditions are afforded, and these conditions are the blacken- 
ing of the hydro-carburets by the hydrochloric acid. In a 
direct experiment with sugar made for this purpose, and in 
which the burning was managed in sucha manner that the 
hydro-carburets being produced at a low temperature floated 
in abundance on the hydrochloric acid, on evaporation in a 
water-bath no reduction of the chloride of platinum could 
be observed. It must be allowed, that in such a trifling case 
of occurrence, the result would not be affected by it. In- 
deed, the formation of hydro-carburets, easily decomposable 
by hydrochloric acid, may be completely avoided by keep 
ing the nearer end of the tube pretty strongly ignited, as the 
hydro-carburets are the more constant when produced at 
high temperatures. 
The highly remarkable and accurate experiments of Fara- 
day on the disengagement or formation of ammonia by the 
fusion of hydrate of potash with a metallic or a non-nitroge- 
nous body, a result which I have also found in all my experi- 
ments (but which was so trifling that it could not be attributed 
to any part played by the nitrogen of the atmosphere), as also 
the investigation of Professor Liebig on the ammonia con- 
tained in rain-water, gives a complete and simple solution of 
the question, from whence comes this disengagement of am- 
monia so often observed and so difficult to be avoided ? 
The experiments of Faraday go entirely to show that there 
is some unknown source of ammonia, and that the nitrogen 
of the atmosphere in his experiments played no actual part ; 
they are so convincing and made without any preconceived 
opinion, that I cannot refrain from giving a short extract from 
them here. They prove, as it appears to me, directly the re- 
verse to the conclusion which M., Reiset has drawn from them, 
and are of the greatest importance in the question, whether 
the nitrogen of the atmosphere plays a temporary part in the 
formation of ammonia by the decay of organic matter, or by 
the oxidation of metals with or without the disengagement of 
hydrogen? An affirmative or negative to this question has a very 
important influence on the theory of the nutrition of plants. 
Faraday observed that an organic substance, the quantity 
of whose nitrogen he wished to estimate, yielded ammonia by 
fusion with hydrate of potash, although he obtained none 
when it was heated alone in a tube. By extending his expe- 
