426 ‘Scientific Intelligence. 
escent film forms upon the surface of o metal during the process of 
cooling. This is probably due to oxydati 
“ Marked changes not only of color but ry in other of the physical 
properties of some of these alloys may be produced by varying the con- 
ditions in which they pass from the liquid to the solid state. These 
in their practical ak but also from affording another instance of the 
phenomena of ‘ tempering’ which may possibly be of consequence in the 
study of this most difficult subject.” 
“In preparing the white alloys containing less than 45 per cent of zine, T have fre- 
quently observed, u pon the under surface of the sheet obtained by pouring off the 
Sa alloy, a thin layer of a soft, tenaciuus, ong e aller. of a ye ee peed 
at as i 
e formation of this singular sheet w attributed to eliquation t 
was difficult to conceive that an alloy ‘erareialy fichier in copper should igri at 
mass in erucible,—which must hav in 
surface of the melted been the 
order ane it should form the bottom of the ingot,—it was thought pteitte ‘that 
volatilization of the zinc might have increased the proportion of copper at the sur- 
) the melte y order to decide this question, a new series of alloys 
prepared, extending from the one obtained b ee together ¥ parts of cop- 
per plus 60 parts , to the mixture of 56 parts of a et i of zine 
—each alloy By ixture Sontein 
‘ a mixtur e per e copper 
than that used in preparing the preceding. Afte 5 dictwcch Asotin pt allen were 
into ingots of about five pounds’ weight. Tn the first four of these alloys— 
. In the series of ingots just mentioned, it oe nevert eles ra traced as 
up as the alloy prepared from 54 parts of copper plus 46 parts of z 
in order to ascertain wine this satt snodifigatton of the 
alloys could be obtained at will, afforded no positive result. An alloy of 42 
pper plus 58 parts inc being prepared, a portion of it was poured ll 
large mass of cold water. The surfaces of many of the granules thus 
cov ee with a sr eion d this pecially true of the 
smallest oF eta but the fil exceedingly thin, and the interior of the granules 
es Se brittle white alloy. r port thrown out upon cold 
iron ~_ to form yv: sheets. A thin yellow fil it is true, 
had previously been heated “ black-hot.” The 1 ow film was still formed where 
the alloy came.in contact with the ingot-mould; it was, however, exceedingly thin. 
On pouring some of the rettaiding alloy into a cold iron mould, a yellow film of the 
eso form ick ~ . obtained. 
wet me the phenomena of tempering exhibited by these alloys are more readily 
perceived among those t the normal color of which is white, it rs bighly probable that 
of these chauetnen with those which are known to occur with alloys of pee and 
tin; * but Dussaussoy+ has already shown that ordinary brass, co ie 6 to 70 per 
* Vid. d’ Arcet in Dictionnaire de de’ Industrie .. x, 500, Art. Tam-tam 
(eis, Baill pent ae et om Peet yen i See aleo Dusennsoy. 
(2) ¥. cit., p. 226, et Tubleau No. 
