26 BULLETIN 521, U. S. DEPARTMENT OF AGRICULTURE. 
Record and report: Each student should make a record of items of 
interest and write a report of the trip in which the following ques- 
tions are answered: What are the requirements of good sirup? 
What equipment is needed? Discuss the degrees of efficiency of 
roller mills in connection with a description of the grinding process. 
What kind of evaporator is best suited to farm use? What is the 
most efficient method of straining the juice? Discuss the use of a 
Baume hydrometer in connection with the boiling of the sirup. 
What factors are to be considered in connection with a prevention of 
the sirup crystallizing? Discuss the use of lime in connection with 
removal of impurities. How is sulphur used? What are the funda- 
mental principles which underly the canning of sirup and other 
food products? What factors will determine the price received for 
the product? 
Note. — This exercise may be adapted to a study of the making of sorghum 
sirup. 
Lessons 19 and 20. — Tobacco. 
Special references. — The following Farmers' Bulletins: 60. Methods of 
Curing Tobacco; 120, The Principal Insects Affecting the Tobacco 
Plant ; 343, The Cultivation of Tobacco in Kentucky and Tennessee ; 
523, Curing Tobacco ; 571, Tobacco Culture. 
Exercise 28. — Production of Tobacco Plants. 
Purpose: To give students practice in management of a seed bed 
and to test depths for planting. 
Directions: Each student should participate in the preparation 
and planning of a seed bed for tobacco and care for the plants until 
they are ready to set out in the field. The work may also include 
the setting of the plants wherever it is possible. A portion of the 
seed bed should be divided to test depth of planting, as follows: (1) 
On the surface, (2) barely covering seeds with soil, and (3) one-half 
inch deep. If it is not possible to have seed beds out of doors, 
small flats may be used in the sunny windows of the laboratory or 
classroom. 
Note. — This exercise should be omitted where tobacco is not an inportant 
crop. 
Lessons 21, 22, and 23. — Sweet Potatoes. 
Special references. — The following Farmers' Bulletins: 321, Sweet Pota- 
toes ; 548, Storing and Marketing Sweet Potatoes. 
Exercise 29. — Propagation of Sweet Potatoes. 
Purpose: To give students practice in the production of plants 
and to furnish material for a study of the sweet-potato plant. 
Directions: This exercise should provide practice to all students 
in each of the following operations: (1) Selection of seed, (2) mak- 
ing of hotbed, (3) planting and care of bed, and (4) drawing and 
