H. Sf F. J. Warth — On Indian Laterite. 



155 



Molecules of water for one molecule of alumina = 3-06, which 

 agrees very closely with the formula of gibbsite, Aj O3 + 3 H^ 0. 

 Specific gravity = 242. 



II. Composition of four Bauxites very rich in alumina, and cofttaining 

 little iron, closely resembling the variety called ' Wocheinite.' 



100-77 100-00 



Molecules of water for one molecule of alumina : 

 2-23 ... 2-11 



100-76 



100-08 



2-67 



If we take the mean of these figures and calculate the proportion 

 of gibbsite and diaspore (AljOgHoO) in the mixture, we find 

 72 per cent, gibbsite and 28 per cent, diaspore. As the proportions 

 vary from 55 per cent, to 88 per cent, gibbsite, we may roughly 

 say that these rich bauxites or ' wocheinites ' consist of about 

 three-fourths gibbsite and one-fourth diaspore. Specific gravities : 

 No. 3 = 2-59 ; No. 5 = 2-39. 



III. Composition of 8 specimens of Laierites in situ which are Bauxites. 



Marwara. Mahab. 



H2O ... 26^82 

 Quartz, Si O3 — 



24^99 



SiO^ 



Ti02 



GaO" 



MgO 



FesOs 



AI2O3 



3-90 

 •38 

 •35 



13-75 

 54-80 



•42 ... 

 ■00 .., 



23-41 .. 

 50-46 .. 



Satara. 

 . 23-88 



. -37 

 4-45 

 •86 



9 

 Mlgiris. 

 . 20^70 . 



,. 3^14 . 



10 

 Nilgiris. 

 . 19^00 .. 

 . 10-52 .. 

 . ^23 .. 

 . -10 .. 

 . -40 .. 



11 12 



Pulsa. Karad. 



15^87 ... 11-82 



. — ... l-Ti 



26^61 ... 37^88 ... 34^37 



3^56 



•13 



•52 



trace 



47-27 



4-20 

 •10 



nil 

 trace 

 51-25 



43-83 ... 38-28 ... 35-38 ... 32-65 ... 30-86 . 



13 



Satara. 

 14-39 



•90 



•64 



•20 



56^01 



26-27 



100^00 100^00 100^00 100^00 100^00 100^00 100-00 100-00 



Molecules of water for one molecule of alumina : 



2-80... 2-83... 3-11... 3-09... 3-07... 2-7 



2-19 ... 3-13 



Average of the above == 2-87, which implies 93-5 per cent, 

 gibbsite to 6-5 per cent, diaspore, with variation from full gibbsite 

 to 60 per cent, gibbsite. 



These bauxites in blocks and in powder are generally red with 

 a shade of brown ; No. 9 is light brown, Nos. 12 and 13 are of 

 a deep red. 



