ANNUAL REPORT, 1936 33 



has been continued and a method developed which is believed to be satisfactory. 

 The method consists of the ignition of the sample in a semi-closed silica tube 

 in the presence of calcium oxide, passing the products of combustion through 

 heated nickel oxide as a catalyst thereby completing the burning, particularly 

 of the "tarry" products. The gases and the iodine are absorbed in appropriate 

 solutions which are later evaporated to dryness and extracted with alcohol. 

 The alcohol extract is evaporated to dryness and the iodine determined by 

 titration with thiosulfate in the usual manner. The apparent improvements 

 consist in the manner in which the combustion is accomplished and the use 

 of nickel oxide as a catalyst rather than the usual platinum. 



The Iron, Copper, Manganese, and Iodine Content of Fruits and 

 Vegetables used as Human Foods. (E. B. Holland, C. P. Jones, and W. 

 S. Ritchie.) Since the inauguration of the project some 126 samples of fruits 

 and vegetables including the skins or tops of some products have been analyzed. 

 This comprises the determination of the various food groups — protein, fat, 

 nitrogen -free extract, fiber, acid soluble ash, and insoluble ash, together with 

 the iron, copper, manganese, and phosphorus content. Analysis of one sample 

 each of milk, codfish and cottonseed maal has been completed and work on 

 eleven samples of cattle feeds, grain, and roughages is under way. 



In addition, eleven new samples of fruits and vegetables, seventeen samples 

 of cereals and cereal products, and two samples of extracted soybean meal 

 have been secured on the open market for analysis. 



The analyses of these samples as well as those obtained in the following proj- 

 ect are virtually complete and should be available for publication in the coming 

 year. 



Absorption by Food Plants of Chemical Elements of Importance in 

 Human .Physiology and Nutrition. (E. B. Holland, W. S. Ritchie, and 

 W. S. Eisenmenger.) Beets, carrots, onions, lettuce, spinach, and swiss chard 

 were raised in lysimeter tanks under special fertilization during the past season 

 to determine the ability of these crops to assimilate iron, copper, manganese, 

 and iodine. Forty-two samples were secured and will be analyzed under the 

 preceding project. The analysis of these samples will soon be completed and 

 results available for publication. 



The Carbohydrates in Kentucky Bluegrass. (E. Bennett.) The pro- 

 cedures of 1935 were continued in the main except that samples were taken early 

 in the morning (8:00 to 9:00 a.m.) rather than late in the afternoon (4:00 to 

 5:00 p.m.). This was done in the hope of effecting a shift in the carbohydrate 

 equilibrium. 



In 1935 all carbohydrates increased in percentage with maturity of the grass, 

 except those soluble in 80 percent alcohol. This group represented by total 

 reducing sugars and sucrose decreased in percentage. The most obvious inter- 

 pretation of such an equilibrium would be that the more complex groups in- 

 creased at the expense of the simple sugars. This is tenable but is probably 

 more apparent than real. 



In 1936 all carbohydrates determined increased in percentage with maturity. 

 The alcohol-soluble fraction increased until the "blossom stage," then de- 

 creased, while those more complex continued to increase as would be expected. 



Hemicelluloses of Tobacco Stalks. (E. Bennett.) Tobacco stalks while 

 valuable as a fertilizer are of interest from the standpoint of waste utilization. 



