The heat of combustion of vegetable proteins / by Francis G. Benedict and Thomas B. Osborne.

  • Benedict, Francis Gano, 1870-1957.
Date:
[1907]
Catalogue details

Licence: In copyright

Credit: The heat of combustion of vegetable proteins / by Francis G. Benedict and Thomas B. Osborne. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    vacuo. If the first determination of the heat of combustion is re- calculated on the assumption that the difference in water deter- minations by the two methods is due to moisture still present in the sample dried only in vacuo we find the heat of combustion to be 5630, which agrees exactly with the second determination, 5629 calories per gram. In confirmation of this result four other samples of edestin were dried in the two ways and the following results obtained, calculated to an ash- and water-free basis; a, moisture determined in vacuo; b, moisture determined by heating at iio° for 12^ hours and then drying in vacuum desiccator for 5 weeks. The result given under a is calculated under c on the assumption that the difference in moisture found between a and b was due to moisture still retained in the samples dried by method a. a b C Edestin No. 40 5500 5622 5623 calories per gram. i ( il 1 5570 5658 5575 “ 1 < (l (l 2 5575 5655 5600 “ <« 11 u 3 5629 5668 5653 “ n f i u 4 .... 5644 t ( 11 The difference in the moisture determinations in samples Nos. 1, 2 and 3, dried by the two methods, is much less than that found for Edestin No. 40 and the difference in the heats of combustion is correspondingly less. In the following tables we give the results of the determina- tions of the heats of combustions of a large number of different vegetable proteins. The condition of these preparations as re- spects drying before using in this work is indicated in Column I by “dried at no°” or “over H2S04” respectively. Under VII is given the heat of combustion as found for the preparation dried only in vacuo calculated to a water-free basis, assuming that the slightly greater loss of weight after drying at no° and then in vacuo is moisture. Amandin. This is a globulin forming the greater part of the protein matter of the seeds of the almond (Prunus amygdalus var. dulcis). Dried at 11 o° in air it has the following composition :l C, 51.30; H, 6.90; N, 18.90; S, 0.43; O, 22.47 per cent. 1 The composition of all these proteins was determined after drying in the customary way at no° in air without subsequent drying in vacuo.