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ni>icro0copical ZTccbntaue. 



Compiled by W. H. B. 



New Method of Preparing Dentine.*— In this method, sug- 

 gested by Lepkowski, it is stated that sections of bone or dentine 

 may be simultaneously softened and stained. The agent used is 

 a modified form of Ranvier's fluid, and is composed of six parts 

 of a r per cent, watery solution of gold chloride to three parts of 

 pure formic acid. The pieces of teeth — which should be J to 

 I mm. thick — are placed in this fluid for twenty-four hours ; they 

 are then removed, washed with distilled water, and placed in a 

 mixture of gum arabic and glycerine for twenty-four hours. On 

 removal from this last re-agent they are again washed with distilled 

 water, then alcohol ; after which they are embedded in celloidin 

 or paraffin. 



To Prevent the Reddening of Canada Balsam. t— The tendency 

 of Canada balsam to become red may be checked, and the 

 balsam bleached by the addition to the solution of a few crystals 

 of pure metallic copper, precipitated from copper sulphate solution 

 by any of the ordinary methods. This process originated with the 

 late Allen Y. Moore, of Cleveland, O., and was the result of acci- 

 dent. What the philosophy of it is we do not know, as the copper 

 crystals do not seem to be changed in any manner, even after long 

 immersion in the solution of balsam. 



An excellent Mounting Medium.; — Dissolve gum dammar in 

 benzole to the consistency of a thin syrup. Get rid of the larger 

 particles of dirt by straining through an old silk handkerchief, and 

 add to the cohate about one-third of its volume of liquor potassse. 

 Shake until mixed, cork well, and set aside in a warm place for 

 several weeks. On examination the mixture will be found to have 

 separated into two layers, the lovver of which (a resin soap) will 

 contain all the impurities, the upper consisting of pure neutral 

 dammar in benzole. Draw this off, and to each ounce add about 

 eight to ten drops of poppy oil. This latter prevents the brittle- 



* Journ. Brit. Dental Assoc. ^ xiv. (1893), p. 248. 

 t National Druo;gist^ \xi. (1892), p. 196. 

 X National Druggist, XX I. (1892), p. 196. 



