1895 THE MICROSCOPE. 77 



QUESTIONS ANSWERED. 



NoTB. — Dr. S. G. Shanks, o/ Albany, N. Y., kindly consents to receive all sorts of ques- 

 tions relating to nticroscopy, whether askfci hy f>rofessionals or aniat,u> s. Persons o/ at, 

 fades of experience , from the beginner uj>7va>d, are lo Icme to the bentjits -/this dtp-i<' 

 tnent. The questions are numbered Jor Jucure > e/erence. 



223. Where can I get Titckerinan^s Lichens f 



Part I is out of print and cannot be got. Part II costs S2.50, 

 postage 5 cents. We can place your order. 



224. Will you wfonn me if the silvered prism arrangement des- 

 cribed in The Microscope, for Nov. 1888, has given good satisfaction f 

 Where can one be obtained ? F. C. Griigan. 



We have no information regarding the performance of the 

 silvered prism described by Dr. Egbert. It seems to have been 

 devised under the impression that a camera box must be 

 placed in a horizontal position when in use. A camera can be 

 easily supported and used in a vertical position, in cases where 

 the microscope body cannot be inclined. The silvered prism 

 seems to have been an unnecessary appliance and was not 

 extensively used. Mr. Zentmayer of Philadelphia could make 

 one. 



PRACTICAL SUGGESTIONS. 



By h. A. WILLSON, 



CLEVELA.ND, OHIO. 



A Cheap Substitute for Selenite. — The following, which 

 first appeared in the American journal of Pharm icy, will be of 

 much interest: 



Ordinary mica (the kind used in stove doors) furnishes a very 

 eflBcient substitute for selenite. Select the clearest pieces, cut 

 them to the desired shape, and slip them under the slide to be 

 polarized. Of course the analyzer and polarizer must be in 

 place. If the first view be not satisfactory give the mica a slight 

 turn upon its axis and see whether in any position a satisfactory 

 color is obtained. 



When found, cut one end square so that it will be parallel 



