1899] MICROSCOPICAL JOURNAL. 249 



Labels. — The preservation of labels of reagent bot- 

 tles is a frequent source of trouble to the working mi- 

 croscopist. A good varnish for this purpose may be made 

 by macerating the following substances, and thoroughly 

 shaking the mixture until all are dissolved: — Sandarac, 

 sixty parts ; mastic, twenty-five parts ; camphor, one part; 

 oil of lavender, eight parts ; Venice turpentine, four 

 parts ; ether, six parts ; and alcohol, forty-four parts. 



Tracing Paper.— It is frequently desirable to supple- 

 ment the records obtained by photographing micro-sec- 

 tions with a drawing, and it would probably be oftener 

 done were it not for the difficulty that many experience 

 when using either the neutral tint reflector or the camera 

 lucida. With a vertical camera and suitable tracing paper 

 this difficulty disappears, and it is possible, after a little 

 practice, to acquire a creditable amount of dexterity in 

 representing the salient features of all objects that do not 

 lequire high-power objectives for their delineation. In 

 making such drawings it is a great advantage to be able 

 to do them direct from the microscope, so that no trans- 

 ference or copying is afterwards needed. For this pur- 

 pose, the following recipe for making a tracing paper, 

 which can be re-converted into ordinary drawing paper 

 after the drawing has been made on it, will be found to 

 be both simple and effective: — Immerse any ordinary 

 drawing paper in a mixture consisting of one volume of 

 castor oil and three volumes of spirits of wine, and hang 

 it up to dry in a warm room for two or three hours. 

 Place a sheet in the focussing screen of the camera and 

 make the drawing, after which place it in a bath of spirits 

 of wine and allow it to remain there until the oil has been 

 dissolved out. The paper will resume its former state 

 and appearance. 



Working Rocks. — The isolation of the skeletons of 

 siliceous organisms, foramens, and other small objects 

 from rock specimens, may be readily effected by first dry- 



