INFANT AND INVALID FOODS. 41 



pure dry sand to the depth of about 5 cm. packing loosely. Cover the upper surface 

 of this material with a film of asbestos and place on it from 2 to 5 grams of the sam- 

 ple of cheese. Place the tube in a continuous extraction apparatus and treat for 

 five hours with anhydrous ether. Remove the cheese and grind to a fine powder 

 with pure sand in a mortar. Replace the mixed cheese and sand in the extraction 

 tube, wash the mortar free of all matters with ether, add the washings to the tube, 

 and continue the extraction for ten hours. 



6. DETERMINATION OF NITROGENOUS COMPOUNDS. 



Make a determination of nitrogen by the Kjeldahl or the Gunning method, using 

 about 2 grams of cheese, and multiply the percentage of nitrogen found by 6.25. 



IT. CEREAL PRODUCTS. 



By A. McGiLL, 

 Chemist of Inland Revenue Laboratory, Ottawa, Canada. 



It has been found impossible to prepare the report on this subject this year. The 

 heading has been inserted here to preserve its proper order. 



V. INFANT AND INVALID FOODS. 



By H. W. WILEY, 

 Chief of Bureau of CJiemistry, United States Department of Agriculture. 



1. GENERAL DISCUSSION. 



Under this head are included all prepared foods of every description, which are 

 intended especially for the use of infants and invalids. 



It is evident that foods for infants should be us nearly as possible similar in charac- 

 ter to the natural food, viz, healthy human milk. All modified milk, of the cow 

 and other animals, intended for infants, would be included in this class. If these 

 milks be evaporated, they would differ from the original sample only in the loss of 

 water, provided the evaporation be carried on in vacuum at low temperature. Many 

 of the foods advertised for the use of infants, however, contain starch and other 

 matters not usually found in healthy human milk. The number of foods advertised 

 for the use of infants is legion. Many of them are "predigested," that is, they have 

 the proteid matter reduced to the form of more or less soluble protein and the starchy 

 matters converted more or less completely into soluble carbohydrates. 



Under the head of infant and invalid foods should also be considered the various 

 products in which nitrogenous bodies are the most important ingredients. 



Infant foods may be divided into two classes: First, milk of cows and other ani- 

 mals modified to resemble more or less completely healthy human milk; and, 

 second, the foods in which carbohydrates are the predominating element. In this 

 connection it may be stated that preparations of this nature are ordinarily used with 

 milk, and may be considered in a sense as substitutes for milk sugar. 



The modification of milk consists as a rule in diminishing the proportion of the 

 protein matter or casein and increasing that of milk sugar and fat. By chemical 

 and other treatment, the ordinary average milk of the cow may thus be modified so 

 as to resemble more or less completely the average healthy human milk. It is 

 planned to examine a large number of infant and invalid foods during the coming 

 year, and for that reason the writer had intended to defer his report until the com- 

 pletion of the work mentioned. So many inquiries have recently been received 

 regarding this subject, however, that ii was thought best to prepare for this bulletin 

 a brief sum i nary of methods to 1 teem ployed with references to a previous publication 

 of the writer's describing them. 



