1892.] THE MICROSCOPE. 125 



24. Eosin and Ca7'7?2i7ze. What are the correct methods 

 for treating material stained i^t eosin and in car7?ti?ieP — 

 H. B. 



Material stained in eosin should be washed in water containing 

 a little acetic acid, which sort of fixes the stain. Material stained 

 in Beale's carmine maybe washed in plain water ; sections stained 

 in Woodward's or borax-carmine should be washed only in acid 

 alcohol ; water will discharge this latter stain. 



25. Thoma Alicrome. Where can I Ji7id a complete descrip- 

 tion^ with the best 77iethods of using it ? — C R. 



Methods in Microscopical Anatomy and Embryology, by C. O. 

 Whitman, published by Cassino, Boston, contains full informa- 

 tion. The last edition of Carpenter on the Microscope contains 

 a fair description ; consult the A. AI. Microscopical Jo2ir7ial 

 Vol. XII, page 35, for a valuable paper on Imbedding and Sec- 

 tioning, by Dr. W. C. Borden. 



26. Rust on steel parts of ^Microtomes. What zvill preve7zt 

 a7id re77iove such rust? 



Vaseline applied will prevent rust. Fine emery paper used 

 with oil will remove it. 



27. Photo77iicrographic Dark R00771. Will so77ie one give a 

 brief but co7nplete description., with the necessary reagents and 

 apparatus ? — E. P. 



A simple dark closet, large enough to contain a table and a 

 shelf or two, may be used. The necessary materials are a ruby 

 lantern, three flat trays, or even plates, if large enough to contain 

 the photo plates, a glass graduate, a small scales, and several bot- 

 tles for solutions. The water supply may be taken from a pail 

 with a rubber tube in the side, furnished with a spring clothes-pin 

 or clip ; the waste vv^ater may fall in a pail below ; a negative 

 rack and a 2-inch camel-hair brush are conveniences. The chemi- 

 cals will depend upon the formula recommended by the maker of 

 the dry plate used, but the following specimen list will do the 

 work : Soda sulphite, eikonogen or hydroquinone, potassium 

 carbonate, and potassium bromide, for developing ; mercury bi- 

 chloride for intensifying ; red prussiate of potash for reducing ; 

 soda hyposulphite for fixing. A printing outfit for paper prints 

 would include one or two printing frames. Sensitized paper, 

 gold chloride, soda acetate, card mounts, and two flat trays for 

 toning and fixing. Washing prints means prolonged soaking in 

 any convenient vessel. Vols. VI and VII of the A. M. Micro- 

 scopical fournal contain a series of excellent papers on photo- 

 micrography, by R. Hitchcock. 



Vol. Xn, page 69, contains a valuable paper by Dr. W. C. 

 Borden, on the choice of plates for photomicrography. 



