13 



THE USE OF AMYLIC ALCOHOL AND SANDARAO 

 IN MICROSCOPY. 



By T. E. Wallis, B.Sc. (Lond.), F.I.C. 



{Bead December 10th, 1918.) 



The object of the present communication is to direct the atten- 

 tion of microscopists to the use of amylic alcohol as a reagent, 

 and to the value of sandarac, also known as gum juniper, as a 

 mountant. By the aid of amylic alcohol the author has been 

 able to prepare a sandarac medium that has a comparatively low 

 refractive index, and which may be used in many instances where 

 glycerine jelly is now employed and enables one to obtain per- 

 manent preparations of objects which either become shrunken 

 t)r are rendered too transparent by the use of benzol- or xylol- 

 balsam. 



Sandarac is a resin imported from North- West Africa, and 

 obtained by incision from the stem of Callitris quadrivalvis 

 Yentenat, N.O. Coniferae. It consists of small cylindrical or 

 stalactitic tears from 5 to 15 mm. long; it has a pale- yellow 

 colour, and is hard and brittle. The refractive index is a little 

 less than that of the dried resin of Canada balsam and is equal 

 to that of oil of cloves. It is easily soluble in ordinary alcohol, 

 amylic alcohol, ether and, by the aid of heat, in fixed oils ; it 

 is only partially soluble in benzol, petroleum spirit, chloroform 

 and turpentine. 



The very pale colour of sandarac has led to attempts to utilise 

 this resin as a mountant, a solution in ordinary alcohol having 

 been recommended for the purpose (1). Such a solution leaves 

 a powdery, fractured film of resin after evaporation of the 

 solvent and is quite useless for microscopical work. There are 

 also some sandarac media, which are prepared according to un- 



