I've melted bronze and small amounts of brass using an oxy acetylene torch and you need to get the metal real HOT to do any pouring or casting. 20 mule team Borax works great as a flux and floats the impurities out to the top of the metal. I stopped melting brass because the cost of the gas needed to get 2-3 lbs of metal molten. One problem I had with bronze is that the zinc vaporizes when heated which as has already stated is nasty stuff.
I've made a forced air redneck's forge to melt aluminum using a steel car wheel, angle iron and a small bathroom vent fan which burns charcoal brickets but it doesn't get hot enough to melt brass. Been looking for a source of soft coal as a hotter fuel to try melting brass with the forge just so I can say I've done it.