Editorial Comment. 321 
From this it appears that, in the case of orthoclase and 
albite, two-thirds of the sihca and all the alkalies are removed. 
In all, over half of the feldspathic constituents are lost dur- 
ing the transition, vv^hile, in the anorthite, only the lime is car- 
ried away. The proportional loss and gain he shows as fol- 
lows : 
Orthoclase 2Si308AlK — 48102 — K2O + 2H2O = SioOc;Al2H4. 
Albite .... 2Si308AlNa — 4Si02 — NaoO + 2H2O = Si209Al2H4. 
Anorthite.. Si208Al2Ca - CaO + 2H2O = Si209Al2H4. 
In other words, two molecules of albite or orthoclase are 
necessary for the formation of one molecule of kaolin, while, 
in the case of anorthite, one molecule is sufficient for one 
molecule of kaolin. 
The formation of kaolin or steinmark, through the de- 
composition of other minerals, as scapolite, leucite, nephelin, 
sodalite, hauyn, analcite, topaz, etc., while in some cases 
regarded as chemically possible, he thinks has not yet been 
proven. 
A mineralogical study of a large number of kaolins showed 
the usual accessory minerals, some of which are original and 
others secondary, the original minerals being, naturally, the 
more refractory constituents, usually existing only in micro- 
scopic proportions, which have escaped the chemical decompo- 
sition. These are mainly apatite, biotite, monazite, xenotine, 
mica, rutile, spene, zircon, etc. Good crystalline forms of 
kaolinite are rarely met with in the kaolins, the material oc- 
curring in small irregular shreds, often so small as to be de- 
termined only with great difficulty. With the kaolin he finds 
associated nontronite (chloropal). 
To the statements generally accepted by American author- 
ities, at least, and put forward originally, I believe, by Kasai, 
to the eflfect that kaolin, as the depth or distance beneath the 
surface increases, will be found to pass gradually into the 
fresh rock from which it was derived, he takes exception, and 
states that such an occurrence has never been actually proven, 
although there are abundant instances of its passing into the 
fresh, undecomposed rock laterally. He would consider 
kaolin as due never to atmospheric action ; that weathering 
and kaolinization are two independent processes ; and that the 
kaolin itself is the product of what he designates as a post- 
volcanic pneumatolytic and pneumatohydatogenic process. 
