246 CHAPTER XIX. 



for many months. For a process of neutralising balsam with carbonate 

 of soda or potash see Ooltjcci (Oiorn. Ass. Med. Natural Napoli, vii, 

 1897, p. 172). 



444. Seilee's Alcohol Balsam {Proc. Amer. Soc. Mic, 1881, 

 pp. 60-2; Journ. Roy. Mic. Soc. [N.S.J, ii, 1882, pp. 126-7).— 

 Dissolve solid balsam in warm absolute alcohol, and filter 

 through absorbent cotton. Objects may be mounted in 

 it direct from alisolute alcohol. I find it for most purposes 

 admirable. It is one of the most stable sohitions known to 

 me. Care should be taken not to breathe on it, as this may 

 cause cloudiness. 



445. Damar (Gum Damar, or Dammar, or d'Ammar). — The 

 menstrua are the same as for balsam. I find xylol the best. For direc- 

 tions for preparing solutions, by various authors, see early editions. 

 After ample experience I am convinced that not one of these solutions 

 can he depended on for permanent preservation. Sooner or later, some- 

 times after a few weeks or days, or it may be only after months or years, 

 granules make their appearance in the mounts. 



446. Colophonium. — A solution of pale colophonium in oil 

 of turpentine keeps well and gives very good definitions. 

 The solution should not be too thick, as it thickens with 

 age. 



This medium drys very slowly (so that ample time is 

 afforded for arranging objects in it). In the winter a slide 

 will take about a month before it will be hard enough to be 

 safe with oil-immersion lenses; whereas an alcohol-balsam 

 mount will be dry enough in a couple of days. It injures 

 alum-hsematein stains ; but with these exceptions I find it a 

 most excellent medium. 



Rbhm {Zeit. wiss. Mih., ix, 1893, p. 387) dissolves 1 part colophonium 

 in 10 of henzin. Solutions in chloroform or xylol are also used by some, 

 see NissL in Encycl. mih. Techn., ii, p. 274. 



447. Venice Turpentine (Vosselee, Zeit. wiss. Mih., vi, 1889, p. 

 292, et seq.). — Commercial Venice turpentine 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. Preparations may 

 be mounted in this medium direct from absolute alcohol. Celloidin 

 sections can be mounted direct from 96 per cent. Stains keep well, 

 according to Vosselee, but Mayer finds hi^malum stains fade in it. 



Stjchannek {ibid., vii, 1896, p. 463) prepares it with equal pai-ts of 

 Venice turpentine and neutral absolute alcohol. 



