ZOOLOGY AND BOTANY, MICROSCOPY, LTC. 121 



pad E presses on the cover-glass. Direct downward pressure with- 

 out displacement of the cover is then attained by further rotation of the 

 screw. 



G ribbon, W.— Mounting Clip. 



English Mechanic, lxxviii. (1904) p. 491 (I fig.). 

 Vi Li, ag 10. — Modern Mounting Methods. 



Tom. cit., p. 490. 



(6) Miscellaneous. 



Waterproof Cement for Glass.* — The following preparations, which 

 are unaffected by water, will be found suitable for cementing glass, 

 repairing troughs, etc. : — ■ 



(1) Dissolve 5 to 10 parts gelatin in 100 parts of water ; add 10 p.c. 

 of saturated bichromate of potassium solution ; mix thoroughly and keep 

 in a dark place. Af ter using the cement the articles are exposed to sun- 

 light, by the action of which the medium is rendered unaffected by 

 water. (2) Quicklime, 1 parts ; litharge, 6 parts ; linseed-oil varnish, 

 1 part. 



Mounting Medium Bottle. f — S. E. Dowdy gives the following 

 directions for fitting up a bottle for holding balsam. Obtain a 1 oz. or 

 I5 oz. wide-mouthed metal screw-stoppered bottle, and bore a circular 

 hole through the lid large enough for a thin glass rod to pass through 

 with plenty of room to spare. Thread the rod on a medium sized cork 

 several diameters larger than the hole in the metal lid, and the thing is 

 finished. Pour the balsam into the bottle, after removing the lid. The 

 length of the rod can be easily altered to suit the depth of the medium. 



Gelatin Plates as Substitute for Glass Light-filters. $ — K. Die- 

 derichs describes a procedure for making light-filters for microscopical 

 and photomicrographical purposes. A solution of the best gelatin, such 

 as is used for making dry plates, is made in the usual way, the propor- 

 tion to the water being as 1 to 200. To the filtered solution 3 c.cm. of 

 1 to 50 aqueous solution of alum are added. 



The films are made by pouring the gelatin on a glass plate placed on 

 a levelling stand. When quite dry the gelatin is overlaid with a film of 

 collodion stained with some anilin dye. 



Red plates may be made as follows : — Dissolve (1) 2 grm. aurantia 

 in 40 c.cm. absolute alcohol, (2) 5 grm. rose Bengal in 20 c.cm. 

 methyl alcohol. Then mix 20 c.cm. of (1) with 10 c.cm. of (2), and 

 add 90 c.cm. of 4 p.c. collodion. Yellow plates can be made by adding 

 20 c.cm. of a saturated alcoholic solution of aurantia to 80 c.cm. 4 p.c. 

 collodion. The gelatin plates may be doubled so as to strengthen the 

 film, or one may be placed on either side of the coloured layer. 



Method of taking Internal Casts of Foraminifera.§— H. J. Quilter 

 obtains perfect specimens by the following method. The shells having 

 been cleaned by boiling in caustic potash, in order to remove all traces 



* Scientific American. See Knowledge, xxvi. (1903) p. 285. 



t English Mechanic, lxxviii. (1903) p. 401 (1 fig.). 



t Zeitsch. angew. Mikr., ix. (1903) pp. 197-8. 



§ Journ. Quokett Micr. Club, viii. (1903) pp. 551-2. 



