7O Answers to Queries. 
solution; use no Canada balsam. Air-bubbles are not pro- 
duced on applying heat. The crude styrax, as purchased, should 
be exposed in a thin layer to the sun for several weeks. The 
yellow colour is thus got rid of as well as the water, and it 
becomes hard. Dissolve in chloroform as above, or, instead, 
benzine, or a mixture of benzine and absolute alcohol may be 
employed in making the solution, while a solution of ether will 
prove valuable when rapid “setting” of the medium is desired. 
In my opinion, it shows the finer parts of objects more clearly. 
Cartilage, when properly stained, shows much better than when 
mounted in glycerine jelly. For histological work, I think it an 
improvement on Canada balsam, etc. Tooth, bone, and other 
sections show better. In botanical specimens it is very good, and 
it shows aleurone grains in sections of castor-oil plant very finely ; 
also, mycelia of fungi show more clearly. Its refractive index is 
higher than balsam—1‘585—and is less brittle. This gives for 
diatoms a marked increase of visibility over Canada balsam, as if 
we take the index of diatomaceous silex to be 1°43, balsam 
gives a visibility of g and styrax more than 15 (Allen and Han- 
bury’s analysis). It appears to keep well. Mr. J. Deby prefers 
the old balsam mount as the safest. 
V. A. LatHam, F.R.M.S. 
318.—Fish-Seales.—For the polariscope balsam is generally 
used, otherwise dry-mounting is preferable. See Sccentific En- 
guirer, Vol. I., pp. 73—91. Viet, 
319.—Teeth and Bone.—Try mounting in styrax or nearly hard 
Canada balsam. I think J. E. Ady’s /accic-occlusion method will 
be found good. See Swentific Enguirer, p. 197, Vol. IL, and 
Science Gossip on balsam mounting. V. A. LATHAM. 
320.—Arranged Diatoms.—This or a similar question was 
asked in Vol. II., but has not been answered. Perhaps the 
enquirer will find the following useful, I having found it so :— 
Febiger’s size, made with acetic acid, 12 drms. ; photographer’s 
gelatine, 2 drms.; alcohol, 1 drm. Use a porcelain dish, add 
acid to gelatine, and stir in a water bath until dissolved ; then add 
the alcohol and filter. Spread on slide with a fine needle. 
V. A, LATHAM. 
320.—To Arrange Diatoms.—I would caution any inexpe- 
rienced microscopist against wasting time in doing what V. A. 
Latham recommends at p. 36. Diatoms are so minute that, no 
matter how finely “gum” may be powdered, it will look like sand 
beside them, and the breath is not sufficient to dissolve any gum 
when in powder on a slide, so as to leave that perfectly even and 
imperceptibly thin film which would fasten the diatoms when 
arranged. Evidently V. A. Latham has heard of breathing on a 
