V O L U M E 25, N O . 10, O C T O B E R 1 9 5 3 tion. Counts for samples under column A were made for 1 minute. Sufficient counts were made under column B to reduce t,he standard error, due t o the random nature of decay, to less than 3%.
1571 sored by the Bureau of Ships, Department of the Navy. The views expressed by the authors are their own and are not t o be considered &a representing the officialviews of the Department of the Navy.
ACKNOWLEDGMENT
Acknowledgment is made to Kenneth Proctor for advioeinreference to analytical procedures. Thanks are expressed to Lt. Comdr. Harry 0. Kulberg, James. E. MoCambridge, and Leonard Zoole for their continued intereat,. This investigation was spon-
73.
LITERATURE CITED
proctar,K, L,,
work,
(2) Thmheiser. G., and Mitteilungen, K. W.. Institut Eisenfmachuw, 22, 260 (1940). R~~~~~~~for Deaember5 , 1952. Aaoepted .rune 25. 1953.
Erythromycin Hydroiodide Hydrate
Contributed by HARRY A. ROSE, Eli Lilly & CO., Indianapolis, Ind.
hydroiodide hydrate was used to determine the E molecular weight of erythromycin base by x-ray methods. RYTHROMYCIN
The compound appears to be a dihydrate. Calculatious based on the analysis of the iodine content indicate a molecular Neight of 905,while the x-ray method indicates 901.8, Crystals suitable for optical and x-ray work may be obtained by crystallizing from aqueous potassium iodide solution.
eter of 114.59 mm. the calculation.
A Nave-length value of2.2896 A. was used in Principal Lines
d
I/&
Face Symbol"
d
I/Ii
Face Symbol
CRYSTAL MORPHOL~CY Crystal System. Orthorhombic. Form and Habit. The crystals are elongated dong the c axis and show the prism (110)and macrodame (101). Axialgatio. a : b : c = 0.925:1:0.786. Interfacial A n g k (I'olnr). l O l n l O l = 80'48'. 110AliO = 94"28'. a Other reflections might contribute to these lines. and the indicated faae symbols a m suggested only as poasible contributing resections.
FUSION DATA. Erythromycin hydroiodide hydrate melts with decomposition in the range 193-195' C. (Kofler hot stage). On cooling, the melt solidifiesas a glass which does not orystalliee.
e-b CI
-b
--a
Figure 1. Typical Crystalsof Erytbmmyein IXydroiodide Hydrate OPTICAL PROPERTIES
,
Refractive Indices (5893 A,; 25' C.). a = 1.528 zt 0.002. P = 1.536 zt 0.002. 7 = 1.550 zt 0.002, Optic Axial Angles (5893 A,; 25' C.). 2V = 75" (mleulated from a. B. and 7 ) . Optic'AxiaI Plane. 1~). Sign of Double Refraction. Positive. Acute Biwtrix. 7 = c. X-RAYDIFFRACTION DATA Cell Dimensions. a = 16.99 A,; b = 18.37 A,; c = 14.43 A. Formula Weighta per Cell. 4 (3.98calculated from x-ray data). Formula Weight. 905 (from iodine content); 901.8 (x-ray). Density. 1.332 (displacement). The fallowing data were obtained using chromium radiation with a vanadium pentoxide filter. The camera.used had a diam-
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