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Analysis of a chromite
May, t89I.]
387
U/zemical Section.
ANALYSIS
OF A C H R O M I T E .
BY H . P E M B E R T O N , J R .
[Read a/Lt~e JneeliT(g~of l~e (.'/~en~ica/ 5"eclion, lzeZd Marclz 27, 1892. ]
On the Pacific Coast of tile U n i t e d S t a t e s t h e r e are several deposits of chromite. A s no c o m p l e t e analysis of any of these m i n e r a l s has, to m y knowledge, b e e n published, it may be of i n t e r e s t to place on record an analysis I m a d e some time ago. According to \Vm. Irelan, Jr., State Mineralogist of California, t h r o u g h o u t the S a n t a L u c i a M o u n t a i n s and t h e coast hills of San L u i s O b i s p o County, Cal., are f o u n d serpentine rocks w i t h b e d s of chromite, in g r e a t e r or less masses existing as loose and f r a g m e n t a r y rocks in t h e ravines and on t h e hillsides, and as pockets and y e i n s on t h e mountains. One of the b e s t m i n e s of the n e i g h b o r h o o d is, the Pick and Shovel, l o c a t e d on the S o u t h F o r k of Chorro. Creek, at an e l e v a t i o n of 1,8oo feet. A sample of the c h r o m i t e from this mine, selected as free from g a n g u e as possible, g a v e on analysis the f o l l o w i n g results : Cr203 . . . . . . . . . . . . . . . . . . . . . . . . . . A120 3 . . . . . . . . . . .
; .
F%O3 . . . . . . . . . . . . . . . . . . . . . . . . . MgO . . . . . . . . . . . . . . . . . . . . . . . . . . FeO,
52'68
. . . . . . . . . . . . .
I I'4O. •
3"52: 16"23
. . . . . . . . . . . . . . . . . . . . . . . . .
I I'77
MnO . . . . . . . . . . . . . . . . . . . . . . . . . .
o'I 1
SiO 2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
3"40
H20 . . . . . . . . . . . . . . . . . . . . . . . . . . .
0"94. too"o 9,
An analysis of t h e g a n g u e s h o w e d it to b e s e r p e n t i n e ; containing a trace only of ferrous oxide. N o o t h e r foreign mineral could be d e t e c t e d on a careful examination. D e ducting, therefore, t h e water, silica, and q u a n t i t y of magnesia (3"26 p e r cent.) c o m b i n e d w i t h t h e silica (as serpentine)
388
C/lemica/
and calculating the remainder the pure mineral : Cr203 . . . . . '. . . . . . . . . . . . AI2()3. . . . . . . . . . . . . . . . . Fe203, . . . . . . . . . . . . . . . . MgO . . . . . . . . . . . . . . . . . FeO . . . . . . . . . . . . . . . . . . MnO, . . . . . . . . . . . . . . . .
&'ctzolz.
[J. F. I.,
to I00 p a r t s , w e o b t a i n for
56'96 I2"32 3'81 t4'o2 i273 o'16
"374 ) "I2t i -= "~t9 -024 "35o) "177 {-= "529 "oo2 )
100"00
R203 : RO = 5~9 : 529 = l'oo : Fo2. The mineral was decomposed by fusion with sodium ear bonate. (Christomanos' process slightly modified.) The m i x t u r e of ore a n d Na,,COa is h e a t e d o v e r n i g h t t)y a B u n s e n b u r n e r , t h e c r u c i b l e b e i n g l o o s e l y c o v e r e d b y its lid. N e x t m o r n i n g it is h e a t e d f o r o n e h o u r o v e r t h e b l a s t l a m p , w i t h f r e q u e n t s t i r r i n g . T h e p r o c e s s h a s t h e a d v a n t a g e of g i v i n g c o m p l e t e d e c o m p o s i t i o n of t h e m i n e r a l , w i t h t h e i n t r o d u c t i o n of n o b a s e s o t h e r t h a n t h e a l k a l i e s . T h e f e r r o u s o x i d e w a s d e t e r m i n e d b y s o l t l t i o n in s u l p h u r i c a c i d in a d o s e d t u b e , u n d e r p r e s s u r e . A c c o r d i n g to F r a n c i s C. P h i l l i p s (Fees. Zeitsc/zrift, 12, I89) 1"34 is t h e s p e c i f i c g r a v i t y of t h e a c i d t h a t is m o s t f a v o r a b l e to t h e s o l u t i o n o f c h r o m i t e in t h i s m a n n e r .
A~ APPARATUS FOR H E A T I N G SUBSTANCES IN G L A S S T U B E S UN>Ea P R E S S U R E . By H. PEMBERTON,JR. [ Re~
C h e m i s t s w h o do n o t h a p p e n to h a v e in t h e i r l a b o r a t o r i e s oil or a i r b a t h s f o r h e a t i n g d o s e d t u b e s , c a ~ m a k e a n a i r b a t h a t s h o r t n o t i c e , f r o m m a t e r i a l s f u r n i s h e d b y all d e a l e r s in s t e a m fittings. O r d e r ."
(5) O n e f o u r - i n c h w r o u g h t - i r o n pipe, e i g h t e e n i n c h e s o u t to out, w i t h u s u a l t h r e a d on e a c h e n d . A t a b o u t n i n e
387
U/zemical Section.
ANALYSIS
OF A C H R O M I T E .
BY H . P E M B E R T O N , J R .
[Read a/Lt~e JneeliT(g~of l~e (.'/~en~ica/ 5"eclion, lzeZd Marclz 27, 1892. ]
On the Pacific Coast of tile U n i t e d S t a t e s t h e r e are several deposits of chromite. A s no c o m p l e t e analysis of any of these m i n e r a l s has, to m y knowledge, b e e n published, it may be of i n t e r e s t to place on record an analysis I m a d e some time ago. According to \Vm. Irelan, Jr., State Mineralogist of California, t h r o u g h o u t the S a n t a L u c i a M o u n t a i n s and t h e coast hills of San L u i s O b i s p o County, Cal., are f o u n d serpentine rocks w i t h b e d s of chromite, in g r e a t e r or less masses existing as loose and f r a g m e n t a r y rocks in t h e ravines and on t h e hillsides, and as pockets and y e i n s on t h e mountains. One of the b e s t m i n e s of the n e i g h b o r h o o d is, the Pick and Shovel, l o c a t e d on the S o u t h F o r k of Chorro. Creek, at an e l e v a t i o n of 1,8oo feet. A sample of the c h r o m i t e from this mine, selected as free from g a n g u e as possible, g a v e on analysis the f o l l o w i n g results : Cr203 . . . . . . . . . . . . . . . . . . . . . . . . . . A120 3 . . . . . . . . . . .
; .
F%O3 . . . . . . . . . . . . . . . . . . . . . . . . . MgO . . . . . . . . . . . . . . . . . . . . . . . . . . FeO,
52'68
. . . . . . . . . . . . .
I I'4O. •
3"52: 16"23
. . . . . . . . . . . . . . . . . . . . . . . . .
I I'77
MnO . . . . . . . . . . . . . . . . . . . . . . . . . .
o'I 1
SiO 2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
3"40
H20 . . . . . . . . . . . . . . . . . . . . . . . . . . .
0"94. too"o 9,
An analysis of t h e g a n g u e s h o w e d it to b e s e r p e n t i n e ; containing a trace only of ferrous oxide. N o o t h e r foreign mineral could be d e t e c t e d on a careful examination. D e ducting, therefore, t h e water, silica, and q u a n t i t y of magnesia (3"26 p e r cent.) c o m b i n e d w i t h t h e silica (as serpentine)
388
C/lemica/
and calculating the remainder the pure mineral : Cr203 . . . . . '. . . . . . . . . . . . AI2()3. . . . . . . . . . . . . . . . . Fe203, . . . . . . . . . . . . . . . . MgO . . . . . . . . . . . . . . . . . FeO . . . . . . . . . . . . . . . . . . MnO, . . . . . . . . . . . . . . . .
&'ctzolz.
[J. F. I.,
to I00 p a r t s , w e o b t a i n for
56'96 I2"32 3'81 t4'o2 i273 o'16
"374 ) "I2t i -= "~t9 -024 "35o) "177 {-= "529 "oo2 )
100"00
R203 : RO = 5~9 : 529 = l'oo : Fo2. The mineral was decomposed by fusion with sodium ear bonate. (Christomanos' process slightly modified.) The m i x t u r e of ore a n d Na,,COa is h e a t e d o v e r n i g h t t)y a B u n s e n b u r n e r , t h e c r u c i b l e b e i n g l o o s e l y c o v e r e d b y its lid. N e x t m o r n i n g it is h e a t e d f o r o n e h o u r o v e r t h e b l a s t l a m p , w i t h f r e q u e n t s t i r r i n g . T h e p r o c e s s h a s t h e a d v a n t a g e of g i v i n g c o m p l e t e d e c o m p o s i t i o n of t h e m i n e r a l , w i t h t h e i n t r o d u c t i o n of n o b a s e s o t h e r t h a n t h e a l k a l i e s . T h e f e r r o u s o x i d e w a s d e t e r m i n e d b y s o l t l t i o n in s u l p h u r i c a c i d in a d o s e d t u b e , u n d e r p r e s s u r e . A c c o r d i n g to F r a n c i s C. P h i l l i p s (Fees. Zeitsc/zrift, 12, I89) 1"34 is t h e s p e c i f i c g r a v i t y of t h e a c i d t h a t is m o s t f a v o r a b l e to t h e s o l u t i o n o f c h r o m i t e in t h i s m a n n e r .
A~ APPARATUS FOR H E A T I N G SUBSTANCES IN G L A S S T U B E S UN>Ea P R E S S U R E . By H. PEMBERTON,JR. [ Re~
C h e m i s t s w h o do n o t h a p p e n to h a v e in t h e i r l a b o r a t o r i e s oil or a i r b a t h s f o r h e a t i n g d o s e d t u b e s , c a ~ m a k e a n a i r b a t h a t s h o r t n o t i c e , f r o m m a t e r i a l s f u r n i s h e d b y all d e a l e r s in s t e a m fittings. O r d e r ."
(5) O n e f o u r - i n c h w r o u g h t - i r o n pipe, e i g h t e e n i n c h e s o u t to out, w i t h u s u a l t h r e a d on e a c h e n d . A t a b o u t n i n e