50 CHEMICAL PHYSIOLOGY. 



(a.) Place in a short piece of the sausage parchment tube, 

 already referred to (Lesson I. 1, h\ 20 cc. of starch mucilage, 

 label it A, and into another, some starch mucilage with saliva, 

 label it B. Suspend A and B in distilled water in separate 

 vessels. 



(b.) After some hours test the diffusate in the distilled 

 water. No starch will be found in the diffusate of either A 

 or B, but sugar will be found in that of B, proving that 

 sugar dialyses, while starch does not. Hence the necessity 

 of starch being converted into a readily diffusible body 

 during digestion. 



7. Action of Malt-Extract on Starch. 



(a.) Rub up 10 grms. of starch with 30 cc. of distilled 

 water in a mortar, add 200 cc. of boiling water, and make a 

 strong starch mucilage. 



(6.) Powder 5 grms. of pale low dried malt, and extract it 

 for half an hour with 30 cc. of distilled water, and filter. 

 Keep the filtrate. 



(c.) Place the starch paste of (a.) in a flask, and cool to 

 60 0., add the extract of (6.), and place the flask in a water- 

 bath at 60 0. 



(d.) Observe that the paste soon becomes fluid, owing to 

 the formation of soluble starch, and if it be tested from time 

 to time (as directed in 4), it gives successively the tests for 

 starch and erythro-dextrin. Continue to digest it until no 

 colour is obtained with iodine. 



(e.) Take a portion and precipitate it with alcohol = achroo- 

 dextrin. 



(/) Boil the remainder of the fluid, cool, filter, and 

 evaporate the filtrate to 20 cc. Add 6 volumes of 90 per 

 cent, spirit to precipitate the dextrin, boil, filter, and con- 

 centrate to dryness on a water-bath, and dissolve the residue 

 in distilled water. The solution is maltose (O l2 H 22 O n + 

 H 2 O). If the alcoholic solution be exposed to air, crystals 

 of maltose are formed. 



