1884.] 



MICKOSCOPIOAL JOUiiNAL. 



thin film is slowly cooling, and not 

 yet wholly ci-ystallized, the contrac- 

 tion sometimes draws in a bubble of 

 air from the ed<^e of the cover. En- 

 tering the still fluid mass, the air 

 makes its way directly to the centre 

 of the region unoccupied by crystals ; 

 but, as it lowers the temperature by 

 its intrusion, the fluid cannot surround 

 it, but a tube of solid sulphur seems 

 to form around it as it advances, leav- 

 ing a central cavity surrounded by a 

 wall exhibiting fine lines of perpen- 

 dicular striation, like the dentine 

 around a tooth pulp-cavity. Vacuoles 

 often arise in the central part of the 

 fluid, and enlarge in a similar man- 

 ner, but without the surrounding 

 wall. Precisely similar vacuoles may 

 be met with in many crystalline rocks. 

 Bisulphide of carbon, boiling oil 

 of turpentine, and some other solvents 

 of sulphur deposit both octahedra and 

 prisms of sulphur from solutions, and 

 a combination of allotropic sulphur 

 and parafhne produces certain modi- 

 fications of its crystalline structure ; 

 but the most remarkable change I 

 have yet noticed was produced by 

 melting yellow sulphur in a mount- 

 ing fluid composed of hard balsam 

 dissolved in absolute alcohol, with a 

 trace of benzole. On stirring the 

 mass it soon became clouded, and 

 under the lens showed clear spaces, 

 intermingled with semi-opaque spots, 

 which show under the J-inch vast 

 numbers of minute spherules of sul- 

 phur and some large ones. These 

 molecules in mass showed violet, 

 blue, red, and other colors by trans- 

 mitted white light. Believing this 

 color to be due to some kind of po- 

 larity in the molecules, I set the prep- 

 aration aside to await developments. 

 It was examined from time to time, 

 and after the lapse of about a month 

 large ramifying crystals of prismatic 

 sulphiu" were found to have formed 

 of a pale yellow color, and each sur- 

 rounded by a clear space bordered by 

 the same fine molecules, which seemed 

 to have been absorbed to form the 

 crystals. The subject of crystalliza- 



tion of inorganic matter in colloid 

 substances is one fraught with inter- 

 est to the student of organic struc- 

 tures, and a study of this form of 

 crystallization may shed some light 

 on such processes. 



Edw'd M. Schaeffer,M.D. 

 Washington, Jan. ist, 1884. 



o 



A New Slide jiiid Slide-Box. 



Messrs. J. W. Qiieen & Co. have 

 recently introduced a modified form 

 of the concave slide, for which some 

 advantages are claimed. It is repre- 

 sented in Fig. I , and it will be seen 



that it difters from the old form in 

 that the concavity is oval instead of 

 round. 



The new box for holding slides is 

 also a modification of, and an im- 

 provement upon, the form they have 

 been selling for some time. The new 

 form is illustrated in Fig. 2. It is 



Fig. 2. 



very substantially made, and has a 

 neat appearance. 



Each box holds twenty-six slides, 

 and on the inside of the cover the 

 name of each object may be written 

 on a line corresponding to the posi- 

 tion of the slide. As will be seen 



