Tlic Georgia Bauxite Deposits. — Jf'atsoii. 33 
Continuing, Laur disting-nishes four types of i)auxite whose 
f armulae are given as follows : 
( Vs H2O ) 
(1) Mixed bauxite of Baux, A+Pe ] V3 Si02 [• + C. 
( V3 FesOa ) 
(2) Pale bauxite of Vilievevrac, A+Pe \ Y^ ?^r? I + C. 
( V2 01 U2 ) 
(3) Red bauxite of the Var, A+Pe \ |- g^O ( _^ ^ 
( '2 r^2(J3 ) 
(4) Pure bauxite of Alabama, A+Pe [ 2 HoO ] + C. 
An abstract in the Chemisches Centrall^latt for 1892, page 
14, of an inaugural dissertation by A. Liebreich in which an 
account of the derivation of bauxite from basalt with special 
reference to the German deposits is given, says, "chemical 
analyses show certain differences in the composition of baux- 
ite from different places, the smaller amoinit of water in the 
French bauxite referring it to diaspore, while the Vogelsberg 
mineral is probably gibbsite (hydrargillite ) [the trihydrate of 
alumina]."* 
The writer has gotten together as many authentic analvses 
of the Georgia bauxites as possible, and from them the ratio 
of AI0O3 to HoO was calculated. Also the sum of the per- 
centage amounts of the impurities SiOo, TiOo and Fe203 is 
^iven. Calculations are made and given for the two types of 
bauxite, namely, (a) the non-ferruginous type, in which the 
iron enters as an impurity; and (b) the ferruginous type, in 
which the iron replaces a part of the aluminum. The analvses 
were carefully selected, and in case of the non-ferruginous 
type only those which gave 55 per cent, and more of ALO. 
were used. This minimum percentage of Al^O., 55 per cent., 
in the non-ferruginous type is the lowest amount of ALO., in- 
dicating the purest grade of the ore. In the ferruginous tvpe 
all analyses are included which show 10 per cent, and more 
of Feod;,,. 
A majorit}' of the analyses used were obtained by analytical 
methods which yield the soluble ALO;,. On a 55 ])er cent. 
AUO^ basis, however, the small percentages of insoluble resi- 
dues (SiOo) indicate that the soluble Al.O., is practicallv the 
eciuivalent of the total ALO.,. This conclusion is based 
upon a close comparison of analyses in which the soluble 
•Quoted by George I'. Mkrrill, Guide to the Collections in the Sections of 
Aophed Geology in the National Museum ; The Non-Metallic Minerals, 1901, p. 
