1815.) Exiract of a Letter from Berzelius ta Gilbert. 47 
Articie IX. 
Extract of a Letter from Professor Berxelius to Professor Gilbert 
Stockholm, Oct, 8, 1814. 
Few letters have given me so much pleasure as that which I 
found from you on my return from Fahlun, where I had been the 
whole summer. I had been long without hearing from you, and 
none of my acquaintances who had been at the battle of Leipsick 
eould give me any information respecting you, I was apprehensive 
in consequence that you were no longer in the land of the living, 
I have not yet auswered the objections of Dr, Fischer, of Breslau, 
to my analysis of nitrate of silver. The experiment of Dr. Fischer, 
whe obtained an explosion by heating nitric acid over muriate of 
silver, did not succeed with me.+ I repeated the experiment ac- 
cording to his directions ; but no explosion followed. After Davy’s 
sxotane became known, I made some experiments. with it, and 
satisfied myself, from, the smell, that whenever concentrated mu- 
riatic acid and concentrated red nitric acid are digested together, 
this remarkable compound is always formed; but I have not ia 
these cases observed any explosion. Warned by Fischer’s state- 
ment, I always placed the vessel in which this mixture was digested 
in a separate and safe place. It is exceedingly probable that this 
peculiar body is nothing else than agua regia quite free from water; 
for it dissolves slowly in water, and forms, as Davy likewise re- 
marked, a weak aquaregia. ‘These few observations show clearly 
that Davy’s analysis of this substance is inaccurate, and that he cor- 
rected his results in consequence of theoretical views. 
Hitherto too little attention has been paid to the combination of 
acids with acids, and to acids free from water. Hence the reason 
why so much of the wonderful has been ebsenved in isolated. obser- 
vations, which, when the whole mass of chemical facts are surveyed, 
va every thing wonderful, and harmonise with our previous know- 
ledge. 
Hor much, for example, have chemists wondered at the smoking 
state of sulphuric acid? yet they missed observing the real nature of 
that body; for though it was known that common sulphuric acid 
contains abundance of water, and that the smoking Nordhauser 
sulphuric acid forms with water common sulphuric acid, and with 
the bases common sulphates ; yet the consequence. was. not.drawn 
the smoking acid contains no water. 
* Translated from Gilbert's Annalen der Physik for Novs I8t4, vol. xviii, 
327. Ihave been induced to publish it here, because it contains-some opinions 
ive to British chemists with which I think they ought to be acquainted, Gjl- 
Rert’s Annalen containg many other similar letters,—T. 
+ The explosion only takes place, as Dr. Fischer has more lately stated, (An- 
nalen, xlvi. 439,) when diluted nitric acid or aqua regia is boiled over horn silver, 
but not when these acids are concentrated,—Guserr. 
