Dr. Pearson's Observations 
418 
grain at all, being quite smooth. Its colour was more like 
that. of silver than any other metal. 
Experiment 12. The metal of which what are called brass 
guns are made, does not in general contain a grain of zinc. 
They are made of an allay of about ten to twelve orthirteen parts 
of copper, with one part of tin. I found that the shavings of 
one of these guns melted much more readily than copper. The 
ingot was not so hard, but tougher than any of the above an- 
cient metals. It possessed nearly the same hardness and 
strength as the allay, in Experiment 3. of twelve parts of cop- 
per by one of till. The colour of the polished surface, and the 
grain and colour of the fractured surface, resembled pretty 
exactly that allay. Of course this gun metal is only a little 
less hard and brittle than the celts, No. 1 and No. 2, but it re- 
sembles them very exactly in the colour and texture of the 
grain. 
This gun metal afforded nearly thirteen per cent, of oxide 
of tin, by means of nitric acid. 
Experiment 13. 20 grains of tin and 10 grains of zinc 
were melted with 800 grains of copper. This allay of eighty 
parts of copper with two parts of tin, and one part of zinc, was 
a metal which had a very different aspect when polished, as 
well as when fractured, from either copper, or any of the above 
allays, or any of the ancient metals. For it had a rich yel- 
lowish or golden hue, and was nearly as tough, but a little 
harder than copper. 
Experiment 1 4. 20 grains of zinc were united by fusion 
with 800 grains of copper. This allay of forty parts of copper 
with'one part of zinc, w 7 as of a yellowish golden hue, and of 
