30 Observations on the Changes which take place 
An annular iron plate or shelf is then applied round the bell ex- 
ternally at about half its height, and on this shelf a fire of turf 
is kindled. The door of the furnace is then closed, and the 
flame plays round the upper part of the bell, till the whole of 
that portion of it which surrounds the vessels or saucers contain- 
ing the amalgam becomes strongly heated. - The distillation of 
the mercury then takes place; it rises in fumes, which falling 
condense in ‘the lower part of the bell and the vessel of water 
beneath. In about eight hours the whole of the mercury is se- 
parated, the furnace is suffered to cool, and the silver (containing 
however some metallic impurities, particularly copper,) is found 
forming beautiful spongy cakes in the iron saucers. This is af- 
terwards melted and refined in the furnaces adjoining to the 
amalgam works, where much of the richer ores, and the produce 
of that which containing larger proportions of other metals had 
been reduced in the blast- farnaces;, 3 is likewise melted and re- 
fined. : 
The operation of which I have now given a sketch, is un- 
doubtedly the most interesting object which Freyberg and its 
neighbourhood afford. The process of amalgamation, in itself 
so curious, is there more extensively and better performed than 
in any other part of Europe. 
V. Observations on the various Changes which take place on 
treating Uric with Nitrous Acid, and on a new Acid callea 
a ig Mecca thence produced. "By Dr, Gasper Bruena- 
TELLI* 
My father (Professor Lewis B.) being occupied in making ex-. 
periments on the human urinary calculi, for a work which will 
be published in the present year, | wished to employ myself in 
examining some of the substances which are most generally found 
with such calculi. In studying the chemical constitution of uric 
acid, I was particularly led to observe some changes which it ex- 
perienced under certain circumstances. Of those observations 
I now undertake to give a brief account, although not without 
that diffidence .which juvenile inexperience in the chemical art 
should inspire. Uric acid differs from the greater part of the 
other known acids, by having a chemical constitution much more 
complicated, the number of its component principles amounting 
to four, which is not the case in the others. Hence it is natural 
to infer, that in whatever manner it may be decomposed, a great- 
* From Brugnatelli’s Journal, lst and 2d bimestrein 1818, . 
variety 
