THE MICROSCOPE AS DETECTIVE 



the advantages possessed by the microscope and 

 also where chemistry scores. 



Very frequently the results of costly law cases 

 hang on the reports of expert food examiners ; every 

 care, therefore, must be taken to avoid error. This 

 being the case, whenever possible, chemical tests 

 should be carried out to confirm the results of micro- 

 scopic examination. When both microscopist and 

 chemist come to the same conclusion, there is not 

 likely to be any mistake. There are tests which 

 the microscope cannot perform, there are some, 

 also, which are beyond the powers of the chemist 

 and many which are very difficult for him. A drop 

 of milk, for example, examined under the micro- 

 scope shows a number of fat globules floating in 

 a watery liquid. However clever the microscopist 

 and however accurate his instrument, he cannot tell 

 if there is an excessive quantity of water, yet a 

 simple chemical test will answer the question. This 

 is a case in which the microscope is of little use, 

 although it is only fair to add that microscopic 

 examination would reveal the presence of blood, 

 hair and dirt, to mention three common impurities, 

 which the chemist in his test for watered milk would 

 quite overlook. With a little care and the use of 

 suitable stains, any bacteria which might be present 

 would also show plainly under a powerful micro- 

 scope. 



Now for an example or two where the micro- 

 scopist has the advantage of the chemist. Some 

 jam makers have been known to be sufi&ciently un- 



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