\0l Professor Hausmann on Metallurgy} c Crysfaxllog rapl/y. 
the contracting power of the sulphuret of copper, is pressed 
through a number of small pores, and receives a determinate 
form, corresponding to these pores. In proportion as the dia- 
meters of the pores are enlarged, the pili become more thick 
and short ; for they cannot stand erect to any height, being curl- 
ed downwards by the power of gravitation. This explanation 
shews, that pili cuprini are not crystalline productions \ nor do 
they admit of a comparison with similar forms, occurring in any 
native metals, such as in silver, where the formation is to be as- 
cribed to an imperfect crystallisation. In the blunter extremi- 
ties, however, of these pili cuprini, I have occasionally observed 
planes of octaedrons. 
c. Aurichalcum . — Aurichalcum of the first fusion, denomina- 
ted area or mengepresm x having a whitish appearance when cut, 
exhibits the elements of crystallisation, and a tendency to the 
octaedral formation, We observe also, that the elementary 
octaedrons are laid one above another in the direction of the 
principal axis. When the dimensions of the octaedrons are 
nearly equal to the elements, then each element formed of 
quadrangular prisms, has the appearance of quadrilateral 
apices, contained in transverse hooked lines, which are some- 
times erect, sometimes curved and rolled together. This cry- 
stalline formation of aurichalcum has been noticed by Grigno- 
nus, who has given a drawing of it, though imperfectly execu- 
ted : it is also noticed by Lampadius. 
d. Arsenicated Nickel. — In the formation of cobaltic glass 
from particles of minerals not oxidised by heat, a mixture of 
metals takes place, which is called Spcise % and which is collected 
at the bottom of the furnace. Along with the cobalt, there is 
often conjoined arsenicated nickel, which is less easily decom- 
posed by heat than arsenicated cobalt ; and for this reason the 
substance called Speise is almost wholly composed of arsenicated 
nickel, besides containing also cobalt and bismuth, and some 
other metals. 
If this residuum is cooled in the common manner, it general- 
ly shews a tendency to crystallisation in the pinnated lines of the 
surface ; and there may also occasionally be observed very small 
crystals in the cavities. But, by a slow process of cooling, large 
crystals are produced, which not unfrequently admit of being 
