iudividuuUy uiuler niagiiilicatioii and dried at 225° C. before weighing;. 

 All silver masses were determined hy double weighings on a Micro 

 balance (sensitivity 1/200 mg.) and corrected for buoyancy, 0.01°/oo 

 impurity, and probable moisture pick-up during weighing period. To 

 each silver sample ca. 20 ml. cone. HXO3 (nitrogen oxide free) were 

 added and after slight heating on a water bath the AgNOs solution 

 was brought up to ca. 200 ml. with conductivity water. To these 

 solutions, P-28 and sample No. 1 were added and mixed. All work 

 was accomplished in darlmess and conductivity water was used 

 throughout. The procedure thereafter followed that of the com- 

 parison teclmiciue with the exception that the mixtures were repeatedly 

 shaken over a period of 12 hours before filtering and very little (ca. 

 1 ml. of NH4SCN) was required by the excess silver nitrate. 



Results: The results of these analyses are shown in the following 

 table. The examination of P-28 by pure silver yielded values in 

 reinarlval)le agreement with the stated value: 



P-28 })y Silver 



19.3747 Mean = 19.3.43 



vStated value=19.;-;74 



Silver analyses of Ice Patrol sample Xo. 1 comj)are very favorably 

 with the results of the comparison teclniif|ue: 



By comparison By silver 



19.3908 19.3896 



As a further check on the entire comparison technique and solution 

 ratios, P-29 Normal Water was run as an uidvnown and confidence 

 in all of the results may he inferred from the agreement between the 

 stated value and the determined clilorinity : 



By cojnparison Stated value 



19.3698 19.370 



As a final check, tlie detei'minations wei-e (>X!imined to see if the 

 amount of excess AgNO^ caused random oi' dii-ectional deviation from 

 the mean. The random deviation noted indicat(>s that neither a 

 deterjuinate solution ratio error nor an indeterminate washing tech- 

 nique error exists. It is b(>lieved the preceision could be improved 

 slightly had weight burettes and larger samples been used. The 

 precision of the chlorinity values given for Ice Patrol samples is 

 ±0.002°/oo C'l and the accuracy is believed to be very nearly 



± 0.002700 CI. 



78 



