64 Microscopical Preparations. 



ARTICLE VIII. — On a method of Preparing and Mounting 

 Hard Tissues for the Microscope ; by Christopher 

 Johnston, M.D.* 



Having for several years occupied my leisure moments with 

 ■what are usually denominated "microscopical studies," I beg 

 leave to offer, as the result of successful experience, a simple and 

 certain method of preparing and mounting hard tissues, such as 

 bone, teeth, shells, fossilized wood, &c. 



I am aware that treatises upon the microscope give a few in- 

 dications for making sections and embalming them in Canada 

 balsam ; but they are unsatisfactory either by reason of their 

 brevity or their want of precision. Specimens may be procured 

 ready-made from the hands of Topping, Bourgogne and others, 

 but while they are expensive, persons in remote situations are 

 obliged to purchase by catalogue without the opportunity of 

 selection. Besides, it is oftentimes difficult or else impossible to 

 obtain series of particular objects, so that the student must either 

 limit his researches or " prepare " for himself : in the latter case 

 he may increase his number of objects indefinitely, and supply 

 himself with many such as are not attainable from abroad, and 

 divided in any direction he may require. 



A microscopic section should be as thin as the structure of the 

 object will allow, of uniform thickness, and polished on both sides, 

 whether it be mounted in the dry way or in balsam. To meet 

 these requirements I proceed as follows : — 



Being provided with 



1. A coarse and a fine 'Kansas hone, kept dressed flat with fine 

 emery ; 



2. A long fine Stub's dentist's file ; 



3. A thin dividing file and fine saw ; 



4. Some Russian isinglass boiled, strained, and mixed with alco- 

 hol sufficient to form a tolerably thick jelly when cold ; 



5. A small quantity of Canada balsam ; 



6. Slides: 1. Clover glass. 



8. One ounce of chloroform ; 9. One of F.F. aqua ammonia. 



10. Some fragments of thick plate (mirror) glass 1 inch square 

 or 1 by 2 inches ; and finally, 



11. An ounce of " dentist's silex," and 



12. Thin French letter paper, of which 500 or more leaves are 

 required to fill up the space of an inch : I examine the object 

 and decide upon the plane of the proposed section. 



* From Sillimarts Journal, 



