Abstract
Nugent and Towle 1 have reported specific gravity values for 33 solutions of beef serum albumin, serum globulin and mixtures of the 2 in the range from 0 to 12% total protein. In all cases the solution contained 0.9% sodium chloride and was adjusted to pH 7.3 to 7.5. Under these conditions, the specific gravity of a solution was shown to be a measure of its total protein content in accord with the finding of Moore and Van Slyke 2 that the specific gravity is a useful measure of total plasma protein in nephritis, more useful in fact than the refractive index, the physical property which has been most widely used in this connection.
At the same time relative viscosity values were obtained for a similar series of solutions which have not previously been reported. The solutions for the relative viscosity measurements were prepared and their specific gravity, salt content and pH value controlled in the same manner as previously described. The relative viscosity measurements were made with a 1 cc. Ostwald viscometer at 25° in a water bath thermostat. Since the relative rates of flow of water and protein solutions through capillary tubes may vary with the applied pressure 3 the values obtained may well be specific for an instrument of the dimensions employed. An instrument of convenient dimensions was therefore indicated since it must serve as a model for others to be employed in checking or utilizing the results. The one chosen for use∗ required a small volume of solution in accord with the amounts of serum usually available in routine clinical work, and was of a type which could be reproduced by an amateur glass blower. (Fig. 1.) The upper and lower bulbs contain respectively 0.6 and 0.9 cc. and their centers are 70 mm. apart.
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