May, 1915
T H E JOURAJAL OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
A NEW TYPE OF APPARATUS FOR THE REDUCTION OF IRON SOLUTIONS BY METALLIC ALUMINUM By c. L. SCXVM*" Received Jsnuary 12, 1915
T h e use of aluminum in t h e form of a sheet for t h e reduction of iron f r o m t h e ferric t o ferrous state was first recommended by W. H. Seamon.' Aluminum wire in t h e form of a spiral in a large test t u b e =.-as worked out independently about t h e same time! at t h e University ,of Michigan b y Professor E. D. Campbell. Since t h a t time the method bas been widely used on account of i t s convenience a n d accuracy. A modification has been proposed with t h e view of eliminating t h c error resulting from t h e oxidation of t h e iron during t h e transfer from t h e reduction t u b e t o the titrating flask. T h e writer has found a very convenient form in a n aluminum chain made from heavy aluminum wire attached t o a glass rod of such length t h a t it projects u p into t h e neck of an Erlenmeyer flask (sce sketch). The reduction and titration may be t h u s carried out in t h e same flasli, t h e chain being casily removed and washed after t h e reduction is complete. This method has the additional advantage of requiring only a small depth 01 liquid. The chain is weighed hefore and after use t o correct for t h e iron present in t h e aluminum. A large numbcr of determinations may be in progress a t t h e same time, for experiment has shown t h a t differences in time of reduction introduce no appreciabla error.
43 1
chromatic photographic plates it was found t o be almost impossible t o secure negatives showing much contrast and sharply defined detail. T o overcome this defect a very simple accessory t o t h e Tassin apparatus was devised as shown in Fig. I ( a ) and ( b ) . Through t h e center of a sheet in. thick and I ' / ~ in, sq).. a in. of brass, A (]Ia2 hole, B, was borcd. T o one side of A was soldered a brass ring, D ( I ' / ~in. i n diameter and in. deep),
Frc. SI-Taien
W ~ T HO n o i ~ n x vISOCEIROYA~XC PLATS
t h e center of t h e ring being concentric with t h e hole B. T o t h e opposite side of A were fastened t,wo spring clips, CC, ' / a in. wide and '(8 in. long. This device was then slipped over t h e lens in front of the vertical illuminator as shown in Fig. I (c), t h e ring D being split in order t o hold A securely in place. After focnsing on t h c ground glass scrccn in t h e usual nianner, a Wratten and Wainwright gelstine light filter ol t h e desired color was slipped iinder t h e
USWIRSXTY OP MICLIICAN. A N N ARBOR
THE USE OF LIGHT FILTERS WITH THE TASSIN METALLOGRAPHIC APPARATUS By FXSDBRICK H. GETMAN
Received January 23, 1915
I n the coursc of certain investigations now in progress in this laboratory i t bccame necessary to employ photomicrographic apparatus for t h e examiliation of metallic surfaces. I n order t o secnre satisiactory illumination, the Tassin electric illuminatorz was used
Fro. I
in connection with a Bausch a n d Lomb microscope and photomicrographic camera. While more or less satisfactory results were obtained with ordinary iso3
w. A N D w.
95.
PANCXROMATIC P L . A ~AND B 11 FILTEK
spring clips CC; and the exposure made with a Wratten and Wainwright panchromatic plate, t h e time of exposure being determined by means of npprcpriate factors for each screen. The Wratten and Wainwright A, B and C screens gave a sufficient range of colors for all ordinary purposes, b u t if i t is desired t o obtain a record of the true color ratios of a heat-tinted specimen t h e K, screen should he used. The accompanying photomicrographs (Figs. I1 and 111) of a polished brass surface, etched with nitric acid, and magnified zoo times, may he taken as typical of t h e results obtained when t h e Wratten and Wainwright filters and plates are used in conjunction with t h e Tassin apparatus. C~Hircd LIIBYIUTORY. ~
West. Chcm. Met.. 4,'105.
* Tasrin, T H ~JSo u a n r ~6, (1914).
Pic. I s r - T ~ ~ i aWITX
BXYN M A W = C o L L s a s
BRVNMAW=.PA.
