264 Prof. Miller on the Form of Crystals of Tin. 
It appears from a mean of the best of upwards of five hun- 
dred observed angles, that 
1 0°3857 
Dn Ones 
and that the angles between normals to the different faces are 
am 45° 0! mt 57°39"3 
ma, 45 O as 68 545 
pp 5718 at 40 50 
Seep ae J! mp 61 23°5 
i# =©98 20 mr $1 26 ™ 
oF. U17. 8 - PP, 39 35 
ap 70 12°5 rr, ‘T& 13°2 
ar 52 534 ss, 29 29 A 
ms %5 15°5 tt, 64 41°3 
Twin crystals occur very frequently, the twin axis being 
either perpendicular to p or to r. 
In the crystals having the twin axis per- m7 p/ ae 
pendicular to p, the angles between normals W~E\WT/ 
to the faces are 
pp! 65°34! mm 57°13! 
rr 120.58 gla — 5 39 
In the crystals having the twin axis per- 
pendicular to the face 7, the angles between ' 
normals to the faces are 
pp 5°39! mm 117 8! 
pp 120 5 rity 54 16 2 
Some very slender capillary crystals of 
tin, said to have been obtained by fusion 
for which I am indebted to Mr. Brooke, 
are regular eight-sided prisms, apparently a combination of 
the forms to which the faces a,m belong. The crystalline 
markings seen on the surface of tin after cooling down from 
a state of fusion very closely resemble the confused crystalli- 
zation which is occasionally produced when the metal is re- 
duced by the galvanic current. Hence in all probability the 
crystals obtained by fusion have the same form as those pro- 
duced by galvanic action. 
At 10%5 C. the specific gravity of the crystals divided by 
that of water is 77178. At the same temperature the specific 
gravity of a mass obtained by fusing the crystals divided by 
that of water was found to be 7°293. 
