652 General Notes. [June, 
fibrous structure. It is readily soluble in water, and has an 
astringent taste. Its composition, according to Kertscher, is: 
SO, Al,O, MgO H,O NaCl 
36.65 7.14 45.01 tr. 
giving the calculated formula 4 MgSO, + Al,S,O0,, + 36 aq. 
=> oroo 
_ Recent LitHorocicaL Work.—It is daily becoming more 
evident that a classification of rocks either by their chemical 
composition alone or by the minerals they contain, is artificial 
and unsatisfactory, and that a true basis of classification is to be 
found only by combining the general . characters of rocks with 
their mode of occurrence as elucidated by field work. Lithologists 
are finding that the microscope and the laboratory are not all- 
sufficient, but that observation of the geological relations of the 
rocks is of the first necessity. Lithology thus rises to a higher 
sphere, and not content with giving a multitude of names to 
rocks of varying texture and in different stages of decomposition, 
is becoming one of the most important methods of geological 
research. sch. 
Perhaps no one is striving more earnestly toward the establis 
ment of this broader method of lithological work than Dr. M 3 
Wadsworth, of Cambridge. In a forthcoming work to be pu 
lished by the Museum of Comparative Zodlogy, he dwells pw 
the importance of grouping the characters of rocks, rather yan 
taking any one character as a basis of classification, and pe : 
pares the usually received classifications with the Linnean a! 
cial botanical classification. é 
In the same essay certain conclusions are reached which a 
much interest, and are often widely at variance with general si e 
ceived theories. He holds that the interior of the earth arr 
liquid, that eruptive, volcanic and plutonic rocks are l 
eruptive, volcanic rocks. Meteorites are regar 
derived from a hot, liquid mass, rather than from a § a e from 
solid body, and it is suggested that they may have S with 
the sun. The appearance of the memoir in full 1s awat i 
interest. 
CHARCOAL AS A PRECIPITANT FOR Gorp.—Mr. ; 
: Davis? (Sr.) has discovered a novel and most intere 
or separating gold from its solution by employing © causing 
has found that charcoal has a remarkable energy 10 “4 * 
1 Journ, Franklin Inst., April, 1883. 
