384 APPENDIX 



GAEBINI (Manuale, p. 31) puts slides for a day into 10 per cent, sulphuric 

 acid, then washes, first with water and then with alcohol. 



BEHRENS (Zeit. f. wiss. Mik., 1885, p. 55) treats slides first with con- 

 centrated nitric acid, then with water, alcohol, and ether. 



JAMES (Journ. Roy. Mic. Soc., 1886, p. 548) treats used slides with a 

 mixture of equal parts of benzin, spirit of turpentine, and alcohol. 



The readiest way known to me of freeing slides from balsam, damar, and 

 cement is to wet with water and scrape with an old knife ; using afterwards, 

 if necessary, one of the solvents mentioned above. 



763. Gum Mucilage, for Labels, &c. The Journ. of the Chemical 

 Soc. says that the adhesive qualities of gum may be very much exalted by 

 the addition of aluminium sulphate (the so-called " patent " alum) to the 

 mucilage. " Two grammes of crystallised aluminium sulphate dissolved in 

 20 grammes of water, is added to 250 grammes strong gum arabic solution 

 (2 grammes in 5 grammes water). Ordinary solutions of gum arabic, how- 

 ever concentrated, fail in their adhesive power in many cases, such as the 

 joining together of wood, glass, or porcelain ; prepared, however, according 

 to the above receipt, the solution meets all requirements " (from Public 

 Opinion, Feb. 19th, 1886). 



FOL (Lehrb., p. 148) advises that slides be prepared for labelling by 

 spreading over one end a layer of aluminium-chloride gelatin dissolved in 

 acetic acid, and allowing it to dry before putting on the label. 



Why do not the glass makers furnish slides with roughened (ground) end- 

 surfaces for the reception of labels ? 



For four other receipts for gums and pastes for labels, see ELIEL, in Engl. 

 Mechan., 1887, p. 535 ; Amer. Mon. Mic. Journ., 1887, p. 93 ; Zeit.f. wiss. 

 Mik., v, 1, 1888, p. 69. 



764. Lubricating Medium for the Thoma Microtome. According 

 to my experience, it is extremely important that sliding microtomes of this 

 class should be so oiled as to reduce friction to the greatest extent possible. 

 I used for a long time the finest watch-maker's oil I could procure. But a 

 mixture, for the knowledge of which I have to thank Prof. v. KOEOTNEFF, 

 is greatly superior. It is simply the usual pharmaceutical mixture of equal 

 parts of castor oil and oil of almonds. It has not only the advantage of 

 being a better lubricant (for this purpose) than the most highly refined 

 animal oil, but also those of having a less oxydizing action on bronze, of not 

 becoming thick by exposure to air, and of not becoming charged with dust 

 to the same extent. 



765. Levulose as a Mounting Medium. Levulose is recommended 

 as a mounting medium by BEHEENS, KOSSEL, u. SCHIEFFERDECKEE (Das 

 Mikroskop. u. d. Meth. d. mile. Unters., Braunschweig, 1889). It is un- 

 crystallisable, and preserves well carmine and coal-tar stains (haematoxylin 

 stains fade somewhat in it). The index of refraction is somewhat higher 

 than that of glycerin. Objects may be brought into it out of water. 



766. Methylen-Blue Impregnation Method (])OGIEL, Arch. f. mik. 

 Anat., xxxiii, 4, 1881), p. 1 in, d seq.). Suitable pieces of tissue (thin mom- 



