14 T. E. WALLIS ON THE USE OF AMYLIC ALCOHOL 



published formulae and of a complex nature (2) ; they are said 

 to be very serviceable (3). 



The amylic alcohol of the British Pharmacopoeia is a purified 

 fusel oil, distilling between 125° C. and 143° C. It is a mixture 

 of amyl and iso-amyl alcohols with small quantities of other 

 alcohols. This alcohol is less volatile and more viscous than 

 ordinary ethyl- alcohol ; it is only slightly soluble in water 

 (about 1 in 40) and is an excellent solvent for volatile and fixed 

 oils, resins and phenolic substances. From a microscopist's point 

 of view amylic alcohol possesses most of the useful properties 

 of benzol and xylol and in addition those of ordinary alcohol^ 

 some, such as miscibility with water, in a less degree and others,, 

 such as its solvent powers for fats and fixed oils, in a more 

 marked degree. It is also miscible in all proportions with 

 ordinary ethyl-alcohol and glacial acetic acid. 



These facts suggest the possibility of using amylic alcohol 

 for the preparation of clearing and dehydrating reagents, and as 

 a solvent for Canada balsam and other resins in the preparation 

 of mounting media. 



When a solution of sandarac in amylic alcohol is allowed to 

 evaporate, it leaves a hard, colourless, varnish-like film of resin 

 which shows no tendency to crack or split away from the slide. 

 This result showed that such a solution of sandarac should prove 

 suitable for mounting microscopic objects. Subsequent experi- 

 ments have fully confirmed this expectation. 



The brittleness of sandarac resin may be still further counter- 

 acted, and the refractive index slightly reduced by the addition 

 of a small proportion of fixed oil. Castor oil is especially suit- 

 able for this purpose, since it is freely soluble in amyl-alcohol 

 and will completely dissolve sandarac resin when the two are 

 heated together ; its refractive index varies from 1-479 to 1-4805 

 at 15° C. 



The following formula was finally adopted : 



Amyl- Sandarac 



Castor oil ... 4 c.c. or 3 grm. 



Sandarac . . .32 grm. ,, 25 „ 



Amylical cohol . . 64 c.c. ,, 50 c.c. 



