ig2 Mr. Hatchett's Experments on the various Alloys, 
the reduction of fine gold to standard for the purpose of coin ; 
but, at the same time, it must be allowed, that the phenomena 
exhibited by arsenic, antimony, zinc, cobalt, nickel, manganese, 
bismuth, lead, tin, iron, and platina, are in many respects re- 
markable, and demonstrate the utility of a regular experimental 
investigation of metallic alloys. 
The contents of the second section show, that numerous 
causes influence the specific gravity of metals ; and, amongst 
these, it has been long ago observed, that some metals, when 
added to others, generally produce contraction in the bulk of 
the mass, or an increase of specific gravity, but that other metals 
produce effects which are precisely the reverse. This, to a cer- 
tain extent, is unquestionably true ; but it does not follow that 
each metal which produces contraction or expansion, when 
added to others, should (as some have supposed) constantly 
produce similar effects, corresponding to the relative proportion 
of that particular metal ; for we well know that some metals, in 
like manner, promote the fusibility of others in a much greater 
degree than could be expected from their natural or inherent 
fusible property; but then, the maximum of this effect is pro- 
duced by certain proportions of the different metals, and suffers 
diminution by any variation in these proportions. It appears, 
therefore, that this great degree of fusibility, is a property pecu- 
liar to the compound, which cannot immediately be attributed 
to either of the component metals ; and I am much deceived, if 
those alterations in specific gravity which, in like manner, are 
observed in the various metallic compounds, will not admit of 
a similar explanation ; for, in respect to the contraction or ex- 
pansion which takes place in consequence of combination, we 
may believe, that there is a maximum of this contraction or 
