Ediforial Comment. 55 
and described, the masks which now obscure them and which 
make them appear similar will be removed, and each one will 
be recognized and easily distinguised from the rest. 
At the present stage of this investigation M. Fouqiie has 
felt warranted in referring to the law of Tschermak, calling 
attention to its crudity and to the frailty of its foundation. 
After acknowledging the beauty and simplicity of the law 
of Tschermak, and its undeniable utility in many min- 
eralogical determinations, he remarks that it encounters two 
objections of equal gravity. These may be given in a free 
translation from his late contribution : 
First, then, if all the lime-soda feldspars result from a simple associ- 
ation of albite and aiiorthite, wlij- is it that one of the parties to this 
association, albite, never shows itself individualized among the crystals 
of volcanic rocks, while the other, anorthite, is very frequently so seen, 
and in a state little short of actual purity. In the zoned individuals, 
composed of different triciinic feldspars, anortliite figures often as an 
element tliat is distinguishable with the microscope, albite never. Here, 
then, is a mineral which is found in very distinct individuals almost 
e.xclusively in stratified or metamorphic regions, which almost never 
appears in a crystalliiu." determinable form in volcanic rocks, but which 
nevertheless, in consequence of its association with anorthite, should be 
of extreme frequence. 
That which gives special force to this objection is the fact that, ac- 
cording to the theory of Tschermak, the complex feldspars are nt)t 
definite chemical compounds, but simple mixtures of those two ele- 
ments, viz., the albiteand the anorthite moh'cules, framed in the same 
crystallographic mould. Each element, in whatever state of division it 
may be supposed to exist, enjoys its proper individualily. In order that 
it may enter into the supposed association it is necessary, in the first 
instance, to admit that its physical molecule has acquired its individual 
constitution and even that it already possesses a crystalline structure 
conformable to that i)f the mineral. In other words, the formation of 
a complex feldspar implies the crystallization of albite, if not before, at 
least concomitantly with the other elements and that, too, under condi- 
tions eminently unfavorable, and actually in a manner which is opposed 
by all that nature teaches of the formation of albite in regions that have 
been studied. 
It is true that albite figuri'S largely in the state of individiuilized crys- 
tals in the potash-soda series, but it is in veins of later dale than the 
formation of the potash feldsfjar, and its formation can be assigned to 
its normal manner of production, in secondary genesis rather than to 
crystallization from fusion. And, as to the rockswliich contain micro- 
litesof albite, recently discovered and studied by Michel-Levy, it is in 
a pre-Tertiary rock much changed, and the albite may have been the 
result of such change. 
