1254 THE BELL SYSTEM TECHXICAL JOURNAL, NOVEMBER 1952 



service which represents a substantial improvement over past design. Its im- 

 portant features include: (a) a frequency band which permits deriving four 

 telephone channels, if desired ; (b) a push-button method for changing frequencies 

 within a matter of seconds; (c) an increase in power over its predecessor; and 

 (d) all-around improved transmission performance. 



Photometric Determination of Aluminum in Lead, Antimony, and Tin 

 and Their Alloijs. C. L. Luke\ Ami. Chem., 24, pp. 1122-1126, July, 1952. 

 (Monograph 2013). 



The work was undertaken because of a need for a reliable method for the 

 determination of traces of aluminum in lead, antimony, and tin and their allo3-s. 

 As a preparatory step toward the dev^elopment of such a method, a thorough 

 study of the specificit}- of the aluminon-thioglycoUc acid and the oxine-cyanide- 

 peroxide photometric aluminum methods was made. As a result, an accurate 

 specific method for aluminum has been developed. This method is appUcable 

 to the analysis of lead, antimonj-, and tin and their alloys and can also be adapted 

 for use in the anal^ysis of a wide variety of other ferrous and nonferrous alloys. 



Photometric Determination in Manganese Bronze, Zinc Die Casting Al- 

 loys, and Magnesium Alloys. C. L. Luke . and K. C. Braun . Anal Chem. 

 24, pp. 1120-1122, July, 1952. (Monograph 2013). 



The work was undertaken in an effort to produce a rapid rehable method for 

 the determination of aluminum appearing as a major constituent in copper, zinc, 

 and magnesium alloj's. The work shows that the photometric aluminum method 

 described by Craft and Makepeace is very satisfactory and that by emplojdng 

 thioglycolic acid as a complexing agent it is possible to simplify the usual photo- 

 metzic methods for the determinatior of aluminum in nonferrous alloys. The paper 

 contains experimental material that wiU aid future workers in the apphcation of 

 this method to other materials. 



Amplifiers J or Multichannel Single- Sideband Radio Transmitters. N 

 Lund', C. F. P. Rose' and L. G. Young'. /. R. E., Proc, 40, pp. 790-796, 

 July, 1952. (Monograph 2012). 



Considerations are given for designing high-frequency ampUfiers whose per- 

 formance will meet the high standards required for amphfying multichannel 

 signals. A relationship between tone and speech data is presented to show how 

 the tone rating of the amplifier can be determined from the speech rating and 

 interchannel modulation noise requirements. 



Measurement of Dynamic Shear Viscosity and Stiffness of Viscous Liq- 

 uids by Means of Traveling Torsional Waves. H. J. McSkimin'. Acousti- 

 cal Soc. Am. Jl, 24, pp. 355-365, July, 1952. 



A short periodically repeated train of torsional waves is transmitted along a 

 glass or metal cylindrical rod. After reflection from the free end, these waves are 



• Bell Telephone Laboratories 



^American Smelting and Refining Company, Barber, N. J. 



