2:U TUE AMERICAN MONTHLY [Aug., 



MICKOSiOPKAL MAMPILATION. 



New Method of Preparing Dentine. — Iiitliis nu'tliod, sug- 

 gestf«l I'y lA'pkowski. it is stated that sections of bono or den- 

 tine 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 1 per cent watery solution of gold chloride to 

 three parts ofi)ure formic acid. The jiieces of teeth, which 

 should be i to J mm. thick, are i)laced in this fluid for twenty- 

 four hours ; they are then removed, washed with distilled water 

 and placed in a mixture of gum arable and glycerine for twenty 

 four hours. On removal from this last re-agent, they are again 

 washed with distilled water, then in alcohol, after which they 

 are embedded in celloidin or paraffin. — Journal British Dental 

 Assnritidon. 



To Prevent the Reddening of Canada Balsam. — The ten- 

 dency of Canada balsam to l)ecome red may be checked, and the 

 balsam bleached by the addition to the solution of a few crys- 

 tals of pure metallic copper, precipitated from copjier sulphate 

 solution by any of the ordinar}' methods. This ])rocess origi- 

 nated with the late Allen Y. Moore, of Cleveland, Ohio, and was 

 the result of accident. What the j)hilosophy of it is we do not 

 know, as the co|)per crystals do not seem to be changed in any 

 manner, even after long immersion in the solution of Ijalsam. — 

 National Druggist. 



Structure of Bacteria. — Sjobring has worked with the Bacil- 

 lu.i anthraci-'<^ a liay bacillus, a vibrio, and several forms of cocci. 

 He fixed the preparations by means of nitric acid, withorwith- 

 out alcohol, and stained with carbol-methylen blue or carbol- 

 magenta red, afterwards decolouring with nitric acid and exam- 

 ining in glycerine and water. — Centr. f. Bakt. u. Parasil. 



Formula for Making Picro-Carmine Stain. — (1) Carmine, 

 1 grm. ; liquor anmionia, 4ccrn. ; mix and add 5 grms, picric acid ; 

 (2) carmine, 15 grms. ; i)icric acid, concentrated solution. Agi- 

 tate the mixture (Ij from time to time for 2 days, let it settle, 

 decant, and evaporate decanted liquor at ordinary temperature, 

 re-dissolve the dry residue in water, making 1 i)er cent or 2 per 

 cent solution ; filter when necessary. Triturate the carmine in 

 water until very fine, add enough ammonia to dissolve the car- 



