226 =©6: SJ. P. Cooke on the Law of Definite Proportions 
are smaller and more frequently isolated than those containing 
exactly two equivalents, A similar fact, it will be remembered, 
is true of the crystals of Sb Znsz. At the alloy of 33 p.c. of 
which exhibits itself in a proneness of the crystals of Sb Znz to 
an excess of zinc. ‘he line &7 has been continued with dots in 
order to show that the influence of Sb Zne extends as far as the 
alloy of 42'8 p.c. of zinc. On returning to the alloy of 31:5 p. ¢. 
b Gnz until the amount of z the alloy had fallen to 27 p.c., 
so that the tendency towards the\¢heoretical composition was so 
great, that in the alloys between 31:5 an of zine, crystals 
alloy of 20:2 p.c. of zinc, very imperfect crystals were obtained 
having almost the same composition as the menstruum. At the 
same time, the crystals became less and less perfect and finally 
disappeared altogether in the alloys below 20 p. ce. of zine. 
e portion of the curve k mn h, is the most important result 
of this investigation and therefore deserves especial notice. It 
has been shown that crystals of the form of Sb Zne, or at least 
crystalline scales of the same character, are formed in the alloys 
between 20 and 43 p. c. of zinc, the first per cent. corresponding 
to Sb Zn and the second to Sb Zns. Half way between these 
two points, that is the alloy of 31:5 p.c., is the point where cryS- 
tals having the calculated composition of Sb Znz are first ob- 
ined. ere the variations in the composition of the crystals of 
Sb Znz exactly proportioned to the excess of zine or of anti- 
