168 The Microscope. 



When put under the lens each crystal will be found to be geo- 

 metrically perfect — something rarely found under the methods 

 usually obtaining in micro-chemical work. Tbe philosophy of the 

 process is plain and needs no explanation. Of course it is presup- 

 posed that the liquid to be crystallized is in a concentrated state. If 

 it is not, it should be made so by careful evaporation down to the 

 point of saturation. With such small quantities this is easily 

 accomplished by placing the containing crystal on a hot slide for a 

 few moments. Where the operation must be repeated it is l^est to 

 use a clean crystal for each portion, or to carefully remove the crys- 

 tal resulting from previous refi'igerations, since the second crop of 

 crj'stals will have a tendency to form around and on the first, thus 

 making masses too large for convenient examination with high powers. 



The use of the pipette for placing the volatile fluid in the 

 upper watch-glass is recommended because of the difficulty of pour- 

 ing small quantities of readily flowing liquids with any exactness, 

 and the consequent danger of having it overflow the container and 

 mix with the fluid to be crystallized. 



It was by following the method here described that I managed to 

 secure the very uniform and beautiful crystals of hrematoidin and 

 cystin which I exchanged with microscopists throughout the country 

 (through the medium of The Microscope,) a few years ago. 



PROCEEDINGS OF SOCIETIES. 



THE MICROSCOPICAL SOCIETY OF BALTIMORE. 



THE Microscopical Society of Baltimore held its regular monthly 

 meeting at the office of Dr. William B. Canfield, 1010 North 

 Charles street, on Monday, April 18, at 8 p. m., the President, 

 Prof. G. L. Smith, in the chair. 



Dr. Canfield showed the Abbe camera-lucida ; the freezing- 

 microtome of Ch. Roy; a convenient form of injecting-syringe with 

 spring attachment to hold the nozzle in place while forcing the in- 

 jecting fluid through the blood-vessels ; and by request, he explained 

 and demonstrated the process of embedding in celloidin. He also 

 showed mounted specimens of: 1. Tubercle bacilli (contrast stain- 

 ing). 2. Anthrax bacilli (contrast staining to show the spores). 3. 

 Spirilla of Asiatic cholera (comma bacilli). 4. Taenia heads. 

 5. Anthracosis, or coal-miner's lung. 



Mr. F. W. McAllister spoke of using gasoline instead of ether 

 in the freezing-microtome. He thought the cost of ether would pre- 



