

198 S. W. Johnson — Coiu/icsitiun <</ tin- Sweet Potato. 



The composition of the sweet potato has been studied by- 

 Proust, Einhof, Payen, Henry, Fromberg, and Antisell. 



Their analyses were mostly made by methods less perfect 

 than those we now possess, and they differ from each other to 

 plained by the variations in quality of the 

 ' f, and some of them are evidently incorrect. 

 Since Mere is to my knowledge no printed summary of these 

 it worth while to reproduce them. 



As chemists are too well' aware, no unexceptionable methods 

 for separating or estimating some of the organic principles of 

 our esculents have as yet been discovered. Since the tendency 

 of newer researches points to the existence in plants of a 

 series of isomeric bodies with the denser and maturer forms of 

 cellulose at one extremity and dextrin at the other, with vari- 

 ous celluloses, starches, amylod os interme- 

 diate', which defy separation and have' loiio resisted identitieation. 

 the best that can be done in proximate analysis is to follow 

 some method conventionally agreed upon, by which fairly com- 

 parable results may be reached. The analysis of the "Nanse- 

 mond Improved" was made essentially according to the plan 

 adopted by the German Agricultural Experiment Station.-, and 

 the results have been for the most Dart verified by repetition 

 and critical examination of the educts. This analysis has re- 

 gard only to the more important food -principles, without refer- 

 ence to traces of malic acid, etc., which have been reported in 



For analysis, about 600 grams of the tubers were thinly sliced 

 i li . i ,. l-7e„ n ,. - d in a warm room and then pul- 

 verized. In 5 grams of air-dry substance, water was estimated 

 by three methods. 



1. By drying at 100° C. in a flask exhausted by the Bunsen- 

 Sprengel pump. This method, winch leads speedily to the de- 

 sired result in case of other vegetable matters, e. g., maize-meal, 

 hay, etc., required several davs' for bnu'j'nj -we<'t-potato flour 

 to a constant weight. 



2. By drying in air-bath at 125° C. This process speedily 

 removes the water but occasioned browning of the substance. 



3. By drying at 100° in a stream of hydrogen, a method 

 somewhat tedious but less so than 1, and now adopted by many 

 of the German Experii t Stat 



The three methods gave of loss on air-dry substance : 



n I 6-90 " 



