286 CHAPTER XX. 



REHM (Zeit. f. wiss. Mik., ix, 1893, p. 387) recommends a solution of 

 1 part of colophoniuin in 10 of benzin; and later writers also recommend a 

 similar solution. 



444, Venice Turpentine for Mounting (VOSSELER, Zeit. /. wiss. 

 Mik., vi, 3, 1889,, p. 292, et seq.). Commercial Venice turpen- 

 tine is mixed in a tall cylinder glass, with an equal volume of 

 96 per cent, alcohol, allowed to stand in a warm place for 

 three or four weeks, and decanted. It is stated that prepara- 

 tions may be mounted in this medium without previous clear- 

 ing with essential oils or the like. The index of refraction 

 being lower than that of the above-named balsams, delicate 

 details are more distinctly brought out. Stains keep well, 

 according to VOSSELER. 



MAYER (Grundzuge, p. 236) notes hereon that not all stains 

 will keep well in it 011 account of the alcohol and oil of tur- 

 pentine in it ; hsemalum stains fade rapidly in it. He con- 

 siders it a very valuable medium on account of its faculty of 

 supporting a notable proportion of water in the preparations. 

 Celloidin sections can be mounted direct from 96 per cent, 

 alcohol ; it does not ca,use turbidity in the albumen of MAYER'S 

 fixative for sections, and you may breathe on it with impunity 

 whilst mounting. This faculty of withstanding* moisture 

 makes it especially valuable at the seaside. 



This medium is also recommended by SUCHANNEK (ibid., 

 vii, 4, 1891, p. 463). He advises that it be prepared with 

 equal parts of Venice turpentine and neutral absolute alcohol 

 (obtained by treating commercial absolute alcohol with cal- 

 cined cupric sulphate and quicklime). The mixture should 

 be agitated frequently and kept in a tile stove for a day or 

 two until clear and sufficiently inspissated. 



445, Thickened Oil of Turpentine (" Verhartzes Terpentinol" 

 of German writers) has been used as a mounting medium by 

 some workers. It is prepared by exposing rectified oil of 

 turpentine in thin layers for some days to the air. All that 

 is necessary is to pour some oil into a plate, cover it lightly 

 so as to protect it from dust without excluding the air, and 

 leave it until it has attained a syrupy consistency. 



446, Cedar Oil. I most highly recommend this oil, both as 

 a temporary examination medium and as a mounting medium. 

 See 438. 



