Experiments on the metabolism of matter and energy in the human body / By W.O. Atwater, PH.D., and F.G. Benedict, PH.D., with the cooperation of A.W. Smith, M.S., and A.P. Bryant, M.S.

  • Atwater, W. O. (Wilbur Olin), 1844-1907.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on the metabolism of matter and energy in the human body / By W.O. Atwater, PH.D., and F.G. Benedict, PH.D., with the cooperation of A.W. Smith, M.S., and A.P. Bryant, M.S. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    vapors passed over hot cupric oxid, as in the first test. The air was then drawn through a tube containing- barium hydroxid, but no carbon dioxid was found. Such tests seemed to show conclusively that there could be no products of incomplete combustion in the burning of alcohol according to this method. As a final check on the accuracy and delicacy of these methods, one arop of 00 per cent alcohol, or about one-twentieth cubic centimeter, was mixed with 400 cubic centimeters of water and the whole placed in a freezing mixture until all but about 30 cubic centimeters had solidi- fied. This liquid was then poured off and tested for alcohol by means of the molybdic-acid solution above described. A very distinct blue coloration was obtained. A part of the remainder of this extremely dilute alcohol solution was then tested for carbon in the same manner as was employed with the condensed vapors from the burning alcohol, namely, by passing a current of the carbon dioxid free air over it and through the combustion tube with hot cupric acid, and finally through barium hydroxid solution. There was a marked cloudiness and white precipitate in the tube containing barium hydroxid. This shows that approximately 1 part of alcohol in 8,000 parts of water can be detected, and it is probable that alcohol and other organic compounds could be detected in a still more dilute solution. That is to say, a solution of one drop, or about 50 milligrams of alco- hol in 400 cubic centimeters of water was frozen until only 30 cubic cen- timeters remained in liquid form. A portion of this unfrozen liquid revealed tlie presence of alcohol by the molybdic-acid test. The remainder of this liquid was evaporated in a current of carbon-dioxid- free air which was passed over copper oxid in a combustion tube and then through a barium hydroxid solution. Tlie precipitate in the latter solution showed the presence of organic material in the liquid. This test indicated that the method could be used as a test for minute quan- tities of alcohol in a liquid. The inference is that any other organic comi)ound, such as acetic acid or aldehyde, that might be contained in the liquid evaporated in the current of air would have been oxidized in the combustion tube, and that its carbon would have appeared as barium carbonate in the barium liydroxid solution. The products of combuvstion of alcohol in the lamp were cooled by a similar freezing mixture. The resulting liquid was concentrated to a small bulk by fractional distillation. A portion of this distillate was tested by molybdic acid solution, but gave no reaction for alcohol. The remainder was evaporated in a current of carbon-dioxid-free air and ])asse(l over lirated copper oxid and through barium hydroxid solution, but gave no reaction for carbon. This negative test, taken in connec- tion with the previous one for the i)resence of gaseous products of inc()iii]>lete combustion of alcohol, which was also negative, implied the absence of any considciabic amount of incompletely oxidized products of combustion when the alcohol was burned in the lamp.