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On the Use of the Microscope as an aid in Chemical Inquiry, 

 By John Davy, M.D., F.R.S., L. & E. ; Inspector-General 

 of Army Hospitals.* 



That the microsope may be an important aid to the chemi- 

 cal inquirer, I believe will be readily admitted by all those 

 who have made trial of it, if tolerably familiar with its use, 

 and in the habit of employing a good instrument. This last 

 condition is essential. To be eminently useful in research, 

 an instrument of the best construction should be employed 

 — an achromatic one, with a magnifying power of at least 

 three hundred diameters. 



Such an instrument may be considered as a new power to 

 the chemist ; making clear what was obscure ; allowing him 

 to distinguish by sight what, without such aid, he could de- 

 termine only by complicated processes of analysis ; enabling 

 him to distinguish, in a mixture of animal and vegetable sub- 

 stances, various tissues and forms, and often in an instant 

 satisfy himself of their nature ; and equally so to satisfy him- 

 self by simple inspection, whether in the preparation of che- 

 mical substances, either by sublimation or precipitation, they 

 are pure and unmixed, or impure and mixed with saline mat- 

 ter, or substances of a different kind thrown down or sub- 

 limed at the same time. 



Taking this view of the application of the microscope, I 

 cannot but think that the time is not far distant when the 

 philosophical chemist will require it as much as, and even 

 more frequently than, the balance ; and that the one will be 

 considered as essential to a laboratory of research as the 

 other ; and to the inquiring traveller, limited as to appara- 

 tus, more useful than any other single implement that can 

 be mentioned hitherto attainable. 



It may not be amiss to give a few examples for the pur- 

 pose of illustration ; making a selection from instances which 

 have come under my own observation, some of which may be 

 new. 



* Medical Gazette. 



