73 
METEORITES AND WHAT THEY TEACH US. 
II. 
By H. HEN80LDT, Ph. D. 
Assistnnt in Natural History, School of Mines, Columbia College, New York. 
Fortunately it is an easy matter to distinguish meteoric 
iron from iron which has been artificially produced, no matter 
when or by whom. If we file or grind a piece of meteoric 
iron so as to produce a smooth, or better still, a polished sur- 
face and apply to this surface a few drops of diluted hydroclo- 
ric, sulphuric or nitric acid,we shall see it covered,as if by mag- 
ic, with extraordinary parallel lines, rods or bars, intersected 
by others under certain definite angles. They are exhibited 
almost invariably by the iron of meteorites and are known as 
Widmanstiittian lines from their first discoverer. They are 
due to a crystalline structure of the iron and to the fact of its 
being nearly always alloyed with a small quantity of nickel 
(also a trace of cobalt and copper). Crystallization, 
as pointed out by Dr. Huntington,' in some respects 
may be looked upon as a purifying process. When a 
mineral crystallizes it invariably endeavors to rid it- 
self of foreign particles, which are generally present, by driv- 
ing them to the periphery where they form a zone or layer. If 
the crystallization is then interrupted and resumed again at a 
later period the expelled matter will form a zone in the crys- 
tal, often of extreme regularity and this ^process may be re- 
peated a dozen times, so that in the sections of many crystals 
we find a series of zones of such foreign particles, each repre- 
senting the outline of the crystal at a certain period of its de- 
velopment. 
Now during the solidification of the meteoric iron there was 
an effort as it were on the part of the pure iron to rid itself of 
the nickel by driving it in successive layers to the margin ; 
thus we have in the meteoric irons bars of almost pure iron, 
the so-called Balkeneisen or kamacite alternating with nar- 
row seams of iron rich in nickel, the taenite or bandei.>«en. 
The Widmanstiittian lines were already discovered in 1808 
and as early as 181G Sommering recorded his opinion, as the 
result of careful angle-measurements, that they were due to an 
' "On the crvstalline structure of irou meteorites" Pror. Am. Ac. 
Cambridge, 1886, p. 491. 
