Brass . 
On this experiment M. Sage observes that there ap^ 
pears to be a point of mutual saturation between the two 
metals, which is when the copper retains one- sixth of 
zinc, and this portion it will retain however long it is heat- 
ed, provided the surface of the melted metal be covered 
to protect the zinc from the action of the air 5 but if the 
brass contains a greater proportion of zinc, precisely this 
excess will escape, even in covered vessels, and will burn 
when it comes out to the air. The same chemist also ob- 
serves that the colour is the finest at the above proportion. 
These experiments seem to require further confirmation; 
but at present we may reckon that to be the most perfect 
brass which is composed o about 14.28 per cent, of zinc 
and 85,7 of copper, and which is not liable to any alter- 
ation in its constituent parts by successive or long con- 
tinued fusions, prov ided the access of air be prevented. 
The analysis of brass has been attempted in various 
ways, and several processes have been given of different 
merit. 
Brass may be to a certain degree analysed by simply 
being kept in fusion at a high heat with free access of air. 
The zinc readily burns, and by far the greater part of it 
escapes, and when the blue flame of the metal ceases the 
‘analysis is supposed to be complete, the loss of weight on 
the remaining metal indicating the quantity of zinc. But 
this is inaccurate from two causes ; first, that a portion of 
zinc always remains in the copper however long the heat 
be continued, and secondly that part of the copper oxy- 
dates in the process, and thereby gains an increase of 
weight. Both these circumstances therefore contribute 
to indicate a smaller proportion of zinc than is really the 
case. 
A simple solution of brass in the sulphuric acid and 
subsequent crystallization has also been recommended, 
gn the idea that the crystals of sulphat of zinc could read! 
