1876.] Microscopy. 309 
toms. — Galloway C. Morris, Tulpehocken Street, Germantown, Phila- 
delphia, Penn. 
Magic-lantern transparencies or cabinet-size photographs of micro- 
scopic objects in exchange for suitable slides. — R. H. Bliven, Elmore, 
0. 
POLARIZING CRYSTALLIZATIONS. — Mr. C. C. Merriman, of Roches- 
ter, gives the following useful hints in regard to the preparation of the 
exquisite polarizing objects contributed by him to the Postal Micro-Cabi- 
net Club: “ All solutions must be in distilled water, and carefully fil- 
tered. Solution of gum arabic must be added to the crystalline solution 
until the drops will dry on the slide without crystallizing. Then the 
drop on the slide is to be held over steam until one or more points of 
crystallization appear; then at once dried over an alcohol lamp; then 
held over the steam again until the crystals have grown a trifle larger, 
and so on until the specimen is satisfactory. The specimens are to be 
first varnished over with a film of collodion, such as photographers use, 
and then mounted in old Canada balsam.” Specimens thus prepared 
have been perfectly preserved for many years, though some of them are 
spoiled by re-crystallization after mounting. é 
 ÅMERICAN Mrcroscoricat Societies. — The following list ot 
microscopical organizations is corrected to date, with the exception of a 
few instances, where further information could not be obtained. Secre- 
=e and others interested are specially requested to furnish such cor- 
rections and additions as may become necessary from time to time. 
Agassiz Institute, Sacramento, Cal. Organized 1872. Meets second 
Tuesday evening of month. President, ; Vice-President, 
Rev. ~ E. Dwinell, D. D.; Secretary, A. P. Andrews ; Cor. Secretary, 
ay July and August, in the hall of the Academy, cor. 19th 
| Race 
Seis ; Cor. Secretary, J. H. McQuillen, M. D. ; Treasurer, Isaac 
hae - D.; Conservator, J. Gibbons Hunt, M. D. 
Sat Se Association for the Advancement of Science ; Microscopical 
sessions Fo, as met occasionally in connection with the migratory 
Buf the association. It is intended to organize permanently at 
Miia meoling next August. 
1865, gg Microscopical Society of the City of New York. Organized 
Bast 10th Se second and fourth Tuesday evenings of the month, at 35 
iam H, ki ‘* resident, John B. Rich, M. D.; Vice-President, Will 
mson, M. D, ; Secretary, C. F. Cox, 13 William St.; Treas 
émieulx ; Curator, O. G. Mason. 
ostal Micro-Cabinet Club. Organized 1875. Business 
