ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 171 



specimen is placed in a watch-glass with the solution, and then covered 

 with a circular glass plate, at the edge of which is an evenly ground 

 ring 1 cm. broad. The aperture is hermetically sealed first with 

 melted wax, and on the following day with amberlac. Later on they 

 are firmly fixed with a mixture of equal parts of guttapercha and 

 tallow. 



Styrax for Mounting.* — Professor A. B. Aubert, referring to 

 Mr, Deby's statement (Vol. V. 1885, p. 745) that styrax never dries 

 completely, states thit his experience with the styrax of commerce 

 has been the same ; but that the southern sweet gum (the exudation 

 of Liquidarnbar styracifliia), when treated as indicated by him,! gives 

 a chloroform solution which hardens as thoroughly as the balsam 

 solution, and has the advantage over it of rendering fine details more 

 visible. As far as he had heard from persons using genuine American 

 styrax (or storax), it has been satisfactory as a mounting medium, 

 hardening thoroughly, and giving clear and in every way excellent 

 mounts. 



Meates's Mounting Medium. — Mr. W. C. Meates writes: — "I 

 make this medium by taking one part of powdered metallic arsenic 

 and six parts of pure sulphur, rub them together in a mortar, and put 

 the mixture in a small test-tube, then apply heat by means of a spirit- 

 lamp ; the ingredients soon unite, and the sulphur turns a deep red. 

 You must go on until the mixture has boiled for a minute or so, then 

 pour it out on to a clean piece of glass, and let it cool. I am in the 

 habit of forming drops on the glass about the size of a large pea, and, 

 before the mixture is cold, keeping another piece of glass upon them 

 so as to flatten them very much, then when cold break them up into 

 small pieces. 



It is very easily used, and it is not even necessary to finish them 

 off with a pretty border, as the sulphide gets so hard when cold, I 

 take a clean cover and place it on a very flat brass mounting table, 

 then place the diatoms on it, and thoroughly dry it ; then put a small 

 piece of the sulphide on the centre, make it hot with a spirit-lamp 

 until it melts and becomes of a deep red colour and on the point of 

 flaming, then place the cleaned side centrally upon it, and with a piece 

 of wood or lead pencil press them well together. The sulphide will 

 extend all round, and on cooling will turn of a canary yellow colour. 

 You can now immediately put the slide under the Microscope. 



With this medium Amphipleura pellucida can be resolved as easily 

 as in Smith's medium. With a Powell oil-immersion 1/8 and oil- 

 immersion condenser I can distinctly see the markings in squares." 



Limpid Solution of Dammar. J — Dr. F. L. James finds no diffi- 

 culty in getting a perfectly limpid solution of dammar if one will only 

 use benzol sufficient to make a solution which will readily pass through 

 filter paper. If the solution be too thin for immediate use, the surplus 

 benzol is easily driven off by evaporation. If the amount be sufficient 



* Amer. Mon. Micr. Journ., vi. (1885) p. 219. 



t See this Journal, v. (1885) p. 744-5. 



X St. Louis National Druggist, vii. (1885) p. 245. 



