Dh. Thomson on the Nutritive Power of Bread of different Countries. 1C3 



enable us to give to charcoal powder any desirable form, and to bind 

 it firmly together, without the intermixture of any impurity. Other 

 agglutinants do not possess the same combination of good properties. 

 Thus, gum arabic is sixteen times as dear, it intumesces under igni- 

 tion so much as often to disrupt the charcoal pastile, and its ashes 

 shine at a high temperature with such intense brilliancy, as to dazzle 

 the eyes of the operator, and make analytical observations impossible. 

 It is probable that rice would form an excellent ingredient in the 

 mixture for Charcoal Galvanic Batteries. 



XL. — On the Nutritive Power of Bread and Flour of different 

 Countries. By Robert D. Thomson, M.D. 



It was observed as early as 1742, by Beccaria of Bologna, in Italy, 

 that flour consisted of two parts differing essentially in their nature ; 

 the starchy part affording, by distillation and digestion, principles 

 similar to those of all vegetables, and the glutinous part, on the other 

 hand, supplying substances similar to those derived from an animal 

 origin.* This discovery constituted the basis of all subsequent 

 researches into the nature and effects of flour as an article of nourish- 

 ment. Indeed, until 1820, Beccaria's method of analysing flour was 

 the only one practised by chemists. In that year, however, Taddey, 

 another Italian chemist, showed that gluten might be separated into 

 two parts by treatment with alcohol — he kneaded the gluten with 

 successive portions of alcohol as long as the latter fluid became milky 

 with water. The alcoholic solution gradually deposited by standing 

 gliadine, while zumome remained unacted on by the alcohol. The 

 gliadine of Taddey was examined also by Saussure and called Mucin, 

 If this substance be separated by filtration and the liquor be evapo- 

 rated, a body termed Kleber by Einhoff, and glutin by Saussure, 

 remains ; while the substance which is untouched by the alcohol is 

 denominated albumen, or at present fibrin. The present method of 

 analysing flour, is to dissolve the gum, sugar, and albumen, by means 

 of water, the flour being placed in a linen bag or towel and exposed to 

 pressure, so as to force out the starch, and leave the glutinous portion 

 on the cloth. The latter when treated with alcohol affords casein, 

 glutin, oil, and fibrin which remains undissolved. According to the 

 present views of chemists, those substances which contain azote are 

 alone capable of forming blood, or in common language, of nourishing 

 the body. It is obvious therefore, that as the azotized principles of 

 flour, viz. albumen, fibrin, casein, and glutin, each contain the same 

 quantity of azote, or 16 per cent., the determination of the amount 

 of this element present in flour, affords us at once an index of the 

 nutritive power of flour or bread ; on this principle the following table 



* Collection Academique, tome xiv., p. I. 



