120 THE AMERICAN MONTHLY. [May. 



volume is systematic and convenient. That adopted in most cases is 

 to give, first, the use of the reagent; next, tests for .its purity; and, 

 lastly, such methods of preparation as are suitable for making smaller 

 quantities for laboratory use. The volume is supplemented by an in- 

 dex, and also by a list of tests arranged under the names of the sub- 

 stances to which they are applied. A number of plates are intro- 

 duced to illustrate the text, and to aid in a clear apprehension of tlie 

 apparatus described. 



As the spectroscope is daily becoming a more prominent aid to ana- 

 htical research, a sliort chapter has been very properly added, describ- 

 ing the simpler and inexpensive forms usually employed in the labor- 

 atory. 



SUBSCRIBERS' NOTICES. 



[These notices will be given six insertions in this column at 25 cents per line or fraction thereof. 

 FOR EXCHANGE.— Slides of selected diatoms. D. B. WARD, Poughkeepsie, N. Y. 



WANTED. — Unmounted microscopical material, also micrographic dictionary. Will exchange or 

 buy. CHARLES VON EIFF, 124 Clinton Place, New York City. 



WANTED — A clean copy of Rev. William Smith's British Diatoms, and Schmidt's Atlas of the 

 Diatomaceae. JAMES B. SHEARF:R, Bay City, Mich. 



OFFERED. — Diatomaceous Earth from Utah (Desert) for Histological Mounts. 



PROF. ORSON HOWARD, Salt Lake City, Utah. 



CORRESPONDENCE invited with a view to the exchange of either mounted orunmounted Oribatida 

 (British) for American species. E. BOSTOCK, Stone, Staffordshire. 



WANTED. — Any works on Microscopy not already in my Library. 



H. M. WHELPLEY, F. R. M. S., St. Louis, Mo. 



Labels in exchange for slides. EUGENE PINCKNEY, Dixon, III. 



First-class Histological Slides for other good mounts; Histological and Pathological material cut on 

 shares. S. G. SHANKS, M. D., 547 Clinton Ave., Albany, N. Y. 



OFFERED.— Griffith & Henfry Micrographic Dictionary to be sold ; also Hoggs Microscope. 



J. P. WINTINGHAM, 36 Pine St., N. Y. 



WAN'l'ED. — A clean copy of WoUe's Fresh- Water Algse of the United States (2 vols.) ; also good 

 second-hand Grunow Camera-Lucida, and a self-centering Turn-table. 



JOS. P. THOMPSON, P. O. Box 1383, Portland, Me. 



FOR SALE CHEAP. — New Gundlach I'g homogeneous-immersion objective, for ,'5 glycerine or 

 water objective. J. M. ADAMS, Water'town, N. Y. 



FOR SALE. — A Bausch & Lomb Stand, A. & C. eyepieces, i in. and i, in. objectives. 



BOX I, Evanston, 111. 



FOR EXCHANGE. — Cabinets of lower Silurian fossils for microscopical apparatus or objects. 

 Correspondence invited. E. L. SHERWOOD, Houston, Miss. 



OFFERED — S400 in prizes. For details see article in January number of this journal for 1890. 



C. A. STEPHENS, Norway Lake, Me. 



