MANUAL OF GENEEAL AGEICULTUEE. 43 



minutes, stirring occasionally, and replacing water should 

 too much evaporate. Add calcium carbonate to neutral- 

 ize the sulphuric acid. Determine when neutral by using 

 litmus paper. "When neutral filter and wash the residue 

 with 15 c.c. of water. Test a few drops of the nitrate with 

 iodin. Have the properties of the starch been destroyed ? 

 Evaporate the remainder in an evaporating dish to about 



10 c.c. Test for glucose or grape sugar with Fehling's 

 solution. 



41. ESSENTIAL OIL FROM PLANTS. 



Materials : Tea, clover, or alfalfa, glass stoppered re- 

 tort (as used in preparation of nitric acid), large test tube, 

 wire gauze. 



Place 5 grams of tea into the glass stoppered retort 

 and add 50 c.c. water. Place the end of the retort in a 

 test tube one-third full of water. Support the apparatus 

 on a ring stand, allowing the retort to rest on a wire 

 gauze. Apply heat and distill 3 or 4 c.c. Observe the 

 color of the distillate (in the test tube.) Is the essential 



011 from tea volatile ? Repeat the experiment, using clover 

 or alfalfa. 



42. EXTRACTION OF PROTEIDS. 



Materials: Flour, cheesecloth, pan, 10% solution of 

 sodium chlorid, test tube. 



A good illustration of protein is gluten, obtained from 

 wheat flour. Mix in a pan with a glass rod 30 grams of 

 flour and sufficient water to make a stiff dough and let 

 stand half an hour in order that the physical properties of 

 the gluten may develop. Place in a cheesecloth and wash 

 in a stream of water, working the dough gently with the 

 fingers. 



Continue washing until the water runs away clear, 

 which indicates that all the starch has been washed out. 

 The gluten remains on the cheesecloth. Treat a small por- 

 tion of gluten with a 10% solution of sodium chlorid. 

 Does it dissolve? 



In California there are no definite divisions between 

 winter and spring wheats. But in localities where this 



