ANALYSIS IN COMMUNICATION RESEARCH 487 



hours and there is great danger that the precipitate will occlude other 

 constituents of the solution. The long exposure on the filter increases 

 the danger of oxidizing the precipitate. On the other hand, a few 

 milligrams of lead sulphide can be precipitated in a sealed tube by a 

 process which produces hydrogen sulphide up to a pressure of ten 

 atmospheres, yet at very little risk of explosion. The resulting pre- 

 cipitate is granular, can be filtered in one or two minutes and its 

 tendency to occlude other metals is much smaller. 



Until recently, the most important industrial applications of 

 analysis were the evaluation of raw and finished products and the 

 control of manufacturing processes, neither of which often demanded 

 special technique. With the growing technical trend in commercial 

 production, however, the analyst is being called upon to provide new 

 services. Industrial research must be guided by frequent analyses, 

 both to determine the nature of newly formed products and to gain 

 knowledge of the mechanisms of particular processes. The great 

 diversity of materials, natural and synthetic, and the intricate and 

 often delicate mechanisms embodied in devices of modern manu- 

 facture, have enormously enlarged the problem of tracing the causes 

 of failure both in the finished product and in the processes entering 

 into its production. Trouble often arises from obscure defects in 

 materials, the nature of which must be discovered by analytical 

 studies. Impurities, minute foreign inclusions, corrosion and tarnish 

 films, chemical changes occurring with aging or produced as an 

 inherent result of the particular combination of materials used, may 

 contribute. 



To make effective use of chemical analysis either as an industrial 

 research tool or as a means of diagnosing manufacturing and mainte- 

 nance difficulties, the necessity of improving the technique is beginning 

 to be recognized here as in other fields. Great flexibility is needed to 

 fit the operations to highly specific problems. Ability to handle and 

 observe small quantities is frequently necessary because of the minute- 

 ness of the phenomena in question. Rapidity is often essential 

 because of the possibility of tying up production, pending solution of 

 the difficulty. 



Realization of conventional limitations has stimulated the search 

 for new methods of approach by which the refinement and extension 

 of analytical technique might be accomplished to fulfill the special 

 needs of both science and industry. An outstanding result has been 

 the development in the analyst of a new mental attitude. He seeks 

 to attain his goal first by reducing the scale of operations to a degree 

 consistent with the small quantities of material frequently handled; 



