184 MARSHALL-BANKS— NEW NEPHELOMETER. [April 23, 



ing power of equal amounts of these proteins, were found : Casein 

 = 0.67 albumin; euglobulin = 0.63 casein; pseudoglobulin = o.5i 

 casein. 



From the results experimentally obtained with various urines 

 and from the differences in the clouds produced by equal amounts 

 of the serum proteins, it may be seen that the nephelometric com- 

 parison of urine, in which these proteins may occur in varying 

 amounts, with any definite standard such as serum cannot give a 

 determination of the total protein. We hope by the use of specific 

 precipitants to apply the nephelometric method to the separate de- 

 termination of albumin and globulin in urine. This may be of value 

 in diagnosis. 



As the object of this paper has been to consider mainly the 

 design of the instrument and the reasons for this design, the dis- 

 cussion of its application to the determination of albumin in urine 

 has of necessity been hardly more than a suggestion of the work 

 along that line. The results of the investigation of this particular 

 problem with the experimental details, will be published shortly. 



Summary. 



1. The previous work in nephelometry has been briefly reviewed 

 and the underlying principles of the nephelometric and turbidometric 

 methods have been compared. 



2. A new form of nephelometer has been described in which 

 columns of suspension of equal lengths are used. The lights re- 

 flected are equalized and compared by means of a movable wedge 

 of neutral tinted glass. Juxtaposition of the two emergent beams 

 is secured by mirrors. 



3. The variations found in preliminary experiments on the 



nephelometric determination of albumin in urine indicated that 



equal amounts of the various serum proteins might give different 



opalescences. Investigation showed that upon precipitation with 



1.87 per cent, of sulphosalicylic acid, the same concentrations of 



serum albumin and serum globulins gave widely different clouds. 



Harriman Research Laboratory, 



The Roosevelt Hospital, 



New York City. 



