EXAMINATION AND PRESERVATION MEDIA. 247 



448. Thickened Oil of Turpentine has been used as a mount- 

 ing medium by some workers. To prepare it, 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. 



449. G-ilson's Sandarac Media [La Cellule, xxiii, 1906, p, 

 427 : the formulae have not been published, on account of 

 the extreme difficulty of preparation, but the products are 

 on sale by G-riibler & HoUborn, even if not listed). There 

 are three of these. They are all of them solntions of gum 

 Sandarac in " Camsal " and other solvents (" Camsal " is a 

 liquid formed by the mutual solution of the two solids salol 

 and camphor). 



(1) Camsal balsam (baume au camsal), propylic alcohol formula ; 

 a mixture of sandarac, camsal, and propylic alcohol, n — 

 1-478. 



(2) Camsal balsam, isobutylic alcohol formula, n = 1'485. 



(3) Euparal, a mixture of camsal, sandarac, eucalyptol, and 

 paraldehyde, n = 1'483. There are two sorts of this, the 

 colourless and the green ("euparal vert"), the latter con- 

 taining a salt of copper, which intensifies h sematoxylin 

 stains. 



Objects may be prepared for mounting in camsal balsam 

 by a bath of propylic or isobutylic alcohol ; and for euparal 

 by a bath of the special solvent (supplied by Griibler & 

 Hollborn under the name of " essence d'euparal "). But this 

 is not necessary. Objects may always be mounted direct 

 from absolute alcohol, and even at a pinch from alcohol of 70 

 per cent. I myself generally prefer alcohol of 95 per cent, 

 (absolute is dangerously volatile for sections). In difficult 

 cases you may pass through a mixture of the medium and 

 the solvent. 



These media vorh very Icvidly, and do not dry too rapidly. 

 They are not ixidant, and preserve delicate stains (perfectly, 

 so far as I know). The mounts seem to keep perfectly, 

 without scaling : all of mine, the oldest being eight years 

 old, have kept without the slightest deterioration in any 

 respect. 



The primary intention of these media is to spare delicate 

 objects the usual treatment with absolute alcohol and 



