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Digestion of raw egg white
May, I922.]
A PRECISION ROTATING SECTOR.
645
that the slit be as narrow as is consistent with obtaining light of sufficient intensity. The disposition of £ and K are shown in Fig. 3 (the tube containing the mirror has been removed). If the sectors be rotated very slowly by hand, it is found that the slit image moves over the scale in a direction opposite to that of the scale. Since the relative velocity of image and scale is twice the peripheral velocity, it is observed that the stroboscopic image of the scale is contracted to one-half of its true width. In spite of this, it is easy to read the scale to o.I of a division. It is, of course, clear that this stroboscopic device may be employed wherever the relative motion of rotating discs is to be measured. Experiments with motors, dynamos, phosphoroscopes, etc., offer opportunities for such applications. A consideration of the possibilities of various alternative schemes involving the use of periodic electrical contacts, sparks, telephones, etc., has convinced the writer that they are all inferior in accuracy to the direct reading of the scale engraved on the rotating discs themselves. The complete instrument with lamp-house and tube containing the mirror and lens system is shown in Fig. 4The application of this instrument to photometry, spectrophotometry and eolorimetry are obvious. Altogether the instrument leaves but little to be desired. The effects of " lost motion," "play," etc., are entirely eliminated, hence this instrument is justly termed " precision rotating sector." In conclusion the writer wishes to thank Mr. J. P. Gaffney, University mechanician, for the great skill and the painstaking care which he has brought to bear on the construction of the instrument. March, 1922. Digestion of Raw Egg White.--MARv S. Rose and GRACE MACLEOD, of Columbia University (]our. Biol. Charm, i922 , 1, 83-88), have studied the digestion of the protein of white of egg by man. The whites of from Io to I2 eggs were consumed daily by each of ten subjects. The coefficient of digestion of cooked whites was 85.9 per cent., of unbeaten raw whites 76.6 per cent., of partly beaten and partly unbeaten raw whites 80. 7 per cent., and of raw whites beaten light 83.8 per cent.; the average coefficient for raw whites of all types was 80.4 per cent. The conclusion is drawn that it is unnecessary to emphasize the difference between raw and cooked eggs, provided the raw eggs be beaten. J . S . tt.
A PRECISION ROTATING SECTOR.
645
that the slit be as narrow as is consistent with obtaining light of sufficient intensity. The disposition of £ and K are shown in Fig. 3 (the tube containing the mirror has been removed). If the sectors be rotated very slowly by hand, it is found that the slit image moves over the scale in a direction opposite to that of the scale. Since the relative velocity of image and scale is twice the peripheral velocity, it is observed that the stroboscopic image of the scale is contracted to one-half of its true width. In spite of this, it is easy to read the scale to o.I of a division. It is, of course, clear that this stroboscopic device may be employed wherever the relative motion of rotating discs is to be measured. Experiments with motors, dynamos, phosphoroscopes, etc., offer opportunities for such applications. A consideration of the possibilities of various alternative schemes involving the use of periodic electrical contacts, sparks, telephones, etc., has convinced the writer that they are all inferior in accuracy to the direct reading of the scale engraved on the rotating discs themselves. The complete instrument with lamp-house and tube containing the mirror and lens system is shown in Fig. 4The application of this instrument to photometry, spectrophotometry and eolorimetry are obvious. Altogether the instrument leaves but little to be desired. The effects of " lost motion," "play," etc., are entirely eliminated, hence this instrument is justly termed " precision rotating sector." In conclusion the writer wishes to thank Mr. J. P. Gaffney, University mechanician, for the great skill and the painstaking care which he has brought to bear on the construction of the instrument. March, 1922. Digestion of Raw Egg White.--MARv S. Rose and GRACE MACLEOD, of Columbia University (]our. Biol. Charm, i922 , 1, 83-88), have studied the digestion of the protein of white of egg by man. The whites of from Io to I2 eggs were consumed daily by each of ten subjects. The coefficient of digestion of cooked whites was 85.9 per cent., of unbeaten raw whites 76.6 per cent., of partly beaten and partly unbeaten raw whites 80. 7 per cent., and of raw whites beaten light 83.8 per cent.; the average coefficient for raw whites of all types was 80.4 per cent. The conclusion is drawn that it is unnecessary to emphasize the difference between raw and cooked eggs, provided the raw eggs be beaten. J . S . tt.