There is but one disadvantage in the case of carbol-xylol; some of the phenols in the market cause a fading of eosin and hæmatoxylin stains. _DeWitt_ has shown that this fault can be corrected by redistillation, stopping the distillation as soon as the temperature begins to rise above the constant boiling point of the phenol; or the carbol-xylol that fades the stains can also be corrected by supersaturating it with a mixture of sodium bicarbonate one part, and sodium-potassium tartrate two parts. Sections kept in xylol or carbol-xylol should be protected from dust and evaporation; it is not a good plan to keep them in these solutions for more than 24 hours. VI. MOUNTING. Permanent mounts are made in glycerin, potassium acetate, lævulose, glycerin gelatin, balsam, damar or colophonium. For celloidin and paraffin sections a solution of =Canada balsam= in xylol is most commonly used for mounting. Celloidin sections (celloidin films are best cut into strips and single sections when in the carbol-xylol; the wheel-shaped paper-cutter used by paper-hangers is the best instrument for this purpose) are lifted onto the slide from the clearing-fluid; folds or wrinkles in the celloidin are straightened or removed by cutting the celloidin at right angles to the section in order to relieve the tension, and the section is then blotted firmly against the slide by means of a pad of absorbent paper. The greatest care should be taken to prevent wrinkling, folding or turning over of the edge of the section. As soon as the pad is removed a drop of balsam is placed upon the section and the cover-glass put over it. There should be just enough balsam used to fill the space between cover-slip and slide, so that air-bubbles are not formed. The balsam must not be so thin that the cover-glass will float about on the liquid, or so thick that it does not spread well. In the latter case warming the slide may cause it to spread more readily, but care must be taken not to injure the stain by over-heating. Paraffin sections on the slide are similarly blotted and covered with balsam and cover-glass; those on cover-slips are blotted between folds of absorbent paper and immediately placed with section-side downward upon a drop of balsam that has been put upon the slide. =Xylol-damar= may be used in place of Canada balsam; it is cheaper and colorless, but it tends to become cloudy. =Colophonium= is the cheapest of the three and has but little color; it is highly recommended by many workers. In a xylol-solution it may be used for aniline stains; a chloroform solution is advisable for the mounting of osmic-acid preparations; while a solution in turpentine and shellac is recommended for Weigert’s neuroglia method, Wright’s blood-stain, and other special staining methods.