148 GLUCOSIDES AND [CH. 



Take six sweet almonds and remove the testas as before. Pound in a mortar and 

 transfer to a flask. Add a little ether and allow to stand for a short time. Pour off 

 the ether, and add a little more which should again be poured off. This removes some 

 of the fat and makes extraction of the emulsin easier. Then extract the residue 

 with about 40c.c. of distilled water and filter. The filtrate contains the enzyme 

 emulsin. . 



Take 10 c.c. of the emulsin solution, and divide it into two portions in two test- 

 tubes. Boil one well (see Expt. 143 a), and to both add equal quantities of a water 

 extract of the amygdalin prepared above. Cork the tubes and insert picric paper 

 with the cork in each case. 



It has been found, as previously mentioned, that emulsin can 

 hydrolyze other glucosides, as for instance, salicin (see pp. 48, 152). On 

 hydrolysis, salicin splits up into salicylic alcohol (saligenin) and glucose. 

 Salicin, itself, gives no colour with ferric chloride but saligenin gives a 

 violet colour, and by means of this reaction the course of the hydrolysis 

 can be followed. 



Expt. 144. To demonstrate the hydrolysis of salicin by emulsin. To 10 c.c. of a 

 1 % solution of salicin in a test-tube add 10 c.c. of the emulsin solution prepared in 

 Expt. 142 or 143. As a control boil in a second test-tube another 10 c.c. of the 

 emulsin solution and add 10 c.c. of salicin solution. After about an hour, add to 

 both test-tubes a few c.c. of strong ferric chloride solution. A purple colour will be 

 given in the first test-tube but no colour in the control. The process of hydrolysis 

 will be accelerated by placing the tubes in an incubator. 



A modification can be made as follows. A second pair of test-tubes should 

 be prepared as before and to both sufficient ferric chloride should be added to give a 

 faint yellow tinge. The unboiled mixture will gradually acquire a purple colour at 

 ordinary temperature. 



Other cyanophoric glucosides are dhurrin, phaseolunatin (linamarin), 

 lotusin and vicianin. 



Dhurrin occurs in seedlings of the Great Millet (Sorghum vulgare). 

 On hydrolysis it yields glucose, prussic acid and parahydroxybenzalde- 

 hyde (C 6 H 4 OH - CHO). It is hydrolyzed by emulsin. 



Phaseolunatin occurs in seeds of the wild plants of Phaseolus 

 lunatus and in seedlings of Flax (Linuiri). It is associated with an 

 enzyme which hydrolyzes it into acetone, glucose and prussic acid. 



Lotusin occurs in Lotus arabicus. On hydrolysis by an accompanying 

 enzyme (lotase) it gives glucose, prussic acid and a yellow pigment, 

 lotoflavin. 



Vicianin occurs in the seeds of a Vetch (Vicia angustifolia). It is 

 hydrolyzed by an accompanying enzyme into prussic acid, benzaldehyde 

 and a disaccharide, vicianose. 



