212 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1939 



Quick results are of great importance, and by hastening the process- 

 ing of the photographic plates used a method has been developed 

 which gives precise quantitative analyses on 6 elements in a single 

 sample in 15 minutes or less. As reported by Vincent and Sawyer,^ 

 spectra for 48 analyses on 8 samples are recorded on each plate, and 

 the posting of results from a plate can be completed within 35 

 minutes after receipt of the samples. Repeat runs were found to 

 be more consistent from the spectrographic laboratory than from the 

 chemical laboratory for such elements as silicon, molybdenum, chro- 

 mium, nickel, manganese, and copper. 



Such successful utilization of the spectograph 20 hours a day 

 in a foundry under industrial conditions of stress, with resulting 

 improvement in precision of results, speed, and decrease in cost, 

 emphasizes that the spectrograph is a practical tool. 



For rapid testing of raw materials special simple types of spectro- 

 scopes have been developed by various manufacturers. A notable 

 example is the Spekker Steeloscope of Adam Hilger, Ltd. This is a 

 small portable fixed-prism spectroscope with a movable eyepiece on 

 which are engraved the various important lines of elements which are 

 to be sought after. A technician of moderate skill, who needs only 

 a reasonable amount of special training, can travel from one car to 

 another of a freight train loaded, for example, with pig iron, carrying 

 his spectroscope and dragging behind him a 220- volt cable carrying 

 direct current to run an electric arc. Selecting a sample pig he strikes 

 an arc between this and a rod of pure iron which he carries for the 

 purpose, and observes the light through his spectroscope, with the 

 eyepiece set for "nickel" or whatever element he is interested in. A 

 special eyepiece can be obtained which, by a clever optical arrange- 

 ment, enables the eye to compare the intensities of two lines. By set- 

 ting this at some predetermined value the operator is enabled to tell 

 at once whether the nickel content, for example, is within the limits 

 of acceptance, and it is thus a job of but a few hours to sample and 

 analyze a whole trainload of iron without even bothering to unload it. 



Such possibilities in industry are almost endless, but since special 

 methods are required for special purposes, their application awaits 

 the demands of industrialists. The first reaction to the spectroscope 

 is usually amazement at its possibilities. Somewhat further investi- 

 gation then frequently brings a reaction of disappointment, because 

 it will not solve every problem which may be presented. The next 

 reaction is that perhaps matters are not so hopeless after all, since a 

 little special attention to each case may show how to get around the 

 difficulty. 



Vincent, H. B., and Sawyer, R. A., Journ. Appl. Phys., March 1937, p. 163. 



