220 



THE AMERICAN MONTHLY [November, 1883. 



guished from foreign silks by examining 

 it under the microscope. Its fibre is 

 round, has a smaller diameter and is not 

 colored very much. The author has 

 determined the largest diameters of single 

 threads of a number of silks with the 

 following results : — 



Real silk (from Bo7nbyx mori) 20 to 257* 

 Senegal silk (from Bombyx FaidJierbi) 



30 to 35/* 

 Ailanthus silk (from Bombyx Cynthia) 



40 to 50|(t 

 Yamamay silk (from Bombyx Yamamay) 



40 to 50|« 

 Tussah silk (from Bombyx Sclent;) 



50 to ss/t 

 Tussah silk (from Bombyx JMylitta) 



60 to 65/t 



The following are the most characteris- 

 tic color-appearances exhibited by these 

 silks : Real silk {Bombyx 7)iori), broad- 

 side, prevailing color bluish-white or 

 yellowish-white, shining ; narrow side the 

 same. Yamamay silk {Bombyx Yama- 

 may), broadside mostly a bluish-white 

 color, with dark blue, bluish-grey, and 

 black shades ; narrow side glaring and 

 fine colors, with dark or black shades. 

 Tussah silk {Bombyx Selene), broadside 

 the fibre is irregular in thickness ; the 

 thickest parts are covered with grey or 

 (mostly) blue spots, whilst the thinnest 

 parts are bluish-white, yellow, or orange- 

 red ; narrow side ground color dark grey, 

 with pink or light green spots. Tussah 

 silk {Bombyx Mylitta), broadside similar 

 to Bombyx Selene, the spots, however, 

 are colored orange-red, red, or brown : 

 narrow side the same as in the case of 

 Bombyx Selene. Ailanthus silk {Bombyx 

 Cy7ithia), broadside shining yellowish- 

 white, with yellow, brown, brownish-grey, 

 or similarly colored places ; narrow side 

 ground color dirty grey or brown to black, 

 with green, yellow, red, violet, or blue 

 spots. Senegal ^\\V {Bombyx Faidherbi), 

 broadside shining yellowish or brownish- 

 white, or pale yellow, grey, brown, and 

 occasionally bluish-white, narrow side 

 grey, brown, or black, occasionally lighter 

 shades. In conclusion, the author men- 

 tions that he has succeeded in separat- 

 ing, quantitatively, a mixture of cotton, 

 sheep's wool, real silk, and Yamamay 

 silk into its four component parts. By 

 boiling the mixture for half-a-minute with 

 hydrochloric acid real silk is separated ; 

 by continuing the boiling for two minutes 

 with concentrated hydrochloric acid 

 Yamamay silk is dissolved, and by heating 

 the residue with potash-lye sheep's wool 



is separated, whilst cotton remains be- 

 hind.— /t??/;-. of Soc. of Chem. Industry, 



— Several correspondents have written 

 in response to the notice published by 

 the editor some time ago, offering to send 

 specimens of Barbadoes earth containing 

 polycystina for mounting. The Editor is 

 obliged to ask their indulgence for a 

 short time, as the material will not be ac- 

 cessable until it is unpacked, being now 

 stowed away in boxes with other micro- 

 scopical specimens. As scon as possible 

 all recjuests will receive attention. 



— At the Annual Meeting of the 

 Ouekett Club, Dr. Matthews exhibited a 

 new form of nose-piece intended to facili- 

 tate the substitution of objectives. It is 

 merely a cone-fitting, without screw or 

 catch of any kind. The hollow cone is 

 screwed on to the stand, and the cone 

 fitting within it to the objective. The fit- 

 ting is tight enough to hold the objective 

 securely, and it is said that the apparatus 

 is both accurate and inexpensive. 



Exchanges. 



Will Exchange. — A new copy of Leidy's Fresh 

 Water Rhizopods of North America, for a good half, 

 or three-fourths inch objective. Address T. B. Jen- 

 nings, Signal Office, Springfield, 111. 



FRE'iH-WATER Alg^ and various pond productions 

 in exchange for same in other places. J. Al. Adams, 

 Watertown, N. Y. 



For Exchange. — First class double-stained sections 

 of Magnolia, Fig, Orange, Oleander, Butter-nut, Birch 

 and many others: also fine injected specimens. N. A. 

 Richards, St. Louis, Mich. 



For Exchange. — Slides of pollen of pitch pine, 

 Finns rigida, with the connection stained, for any 

 named slides of alg:e. Dr. C. F. Millspaugh, E. M. 

 S., Binghampton, N. Y. 



Wanted. — Trichina Spiralis, Pleurosigma Ang., or 

 other well-mounted slides in exchange for fine s!id.-s. 

 Insects, Acari, Spermatozoa of Horse, Physiological 

 and Pathological preparations. J. O. Stillson, M. D., 

 504 Upper Second Street, Evansville, Ind. 



Fo-sil Diatoms from Carson, Ncv., and Posa Creek, 

 Cal., slides or matcri.il to exchange for good diatoms, 

 mounted or material. Also, many other diatoms; lists 

 exchanged. The above deposits are rich and newly dis- 

 covered by myself. F. H. Engels, M.D., Virginia, Nev. 



