INDUSTRIAL RESEARCH 



the investigator influence greatly the course 

 of the research. For example, a chemist using 

 a microscope may be motivated to set up a 

 wet analytical laboratory centered about a 

 microscope under which he 'observes reac- 

 tions between minute (juantities of sample 

 and reagents. In contrast, a metallurgist 

 may make microhardness tests on his par- 

 ticular specimen with the aid of a micro- 

 scope. Whatever the specific purpose, one 

 of the most important abilities de\Tloped by 

 experience is that of devising techniques 

 which will yield more significant data from 

 the samples to be studied. Frequently, the 

 development of techniques involves only the 

 adaptation of existing ones to specific needs, 

 but sometimes leads to a drastic departure 

 from conventional methods. Appropriate 

 techniciues are often the products of crossing 

 disciplines, instrumentation, or sample ma- 

 nipulation. It maj^ be found that there is a 

 need to resort to one or all of these expedients 

 during the course of a research project. 



This article is based on experience which 

 can be classed as applied industrial research, 

 part developmental and part trouble shoot- 

 ing. There is little difference in the general 

 approach to either type problem. 



Sample selection is an important pre- 

 requisite to the experimental work. Because 

 of the limitations m the size of the micro- 

 scopical sample, utmost attention must be 

 devoted to the problem of taking a repre- 

 sentative sample. Sampling should be ac- 

 complished with critical awareness of the 

 prior history of the sample, the seciuence of 

 events occurring throughout the entire 

 process from which the sample is extracted, 

 and the nature of the chemical and physical 

 environments in all stages of the sample 

 history. In general, it is safer to take large 

 samples first, and then later, as decided by 

 more critical examination, to reduce the 

 sample size. This necessitates that observa- 

 tions of gross structure be made first at unit 

 or low magnification and subsequent study 

 carried out at higher magnification. Initially, 



Fig. 2. The Leitz Ortholux microscope shown 

 in combination with the Aristophot photomicro- 

 graphic camera. 



for example, the binocular stereomicroscope 

 is indispensable. 



The decision in the choice of samples is 

 usually followed by sample preparation and 

 the selection of types of illumination. There- 

 fore, the remainder of this section will be 

 confined to comments upon combination of 

 disciplines and sample preparation. The 

 employment of a microscope to study struc- 

 ture does not exclude the application simul- 

 taneously, or at another time, of other disci- 

 plines such as wet chemistry, photometry, 

 absorption and emission .spectroscopy, to 

 name but a few. There should be no restric- 

 tions which prevent the microscopist from 

 bringing any suitable tools to bear upon the 

 problem. For example, microscopy is an 

 excellent tool to select and isolate specimens 

 suitable for identification by X-ray diffrac- 

 tion and other microanalytical methods, and 

 it should be possible to use these freely, 

 where indicated. 



371 



