S-- 



9817.725 

 200.2 + m 



4.2534 



(1) 



The best fit of the February 19(30 measurements to tliis curve was 

 obtained by using a standardization correction of 0.054 in X-dial 

 reading so that a reading of 49.857 corresponded to a saHnity of 35°/oo. 

 After the addition of 0.143 to the values of m (bringing the selected 

 point to »S'=35°/oo corresponding to w = 50.000) a preliminary evalua- 

 tion was made of the constants for a calibration curve assuming a 

 second degree relationship between conductivity and salinity. In the 

 relationship assumed, C= Cri5(K-\- LS-\- MS'^) where C is the conduc- 

 tivity at any salinity S and C^r^ is the conductivity at a salinity of 

 35°/oo and K, L, and M are constants. This calibration curve has 

 the form: 



S-- 



-L±^ D-4MI 



K 



{m'+By 

 im+B)_ 



2M 



where K, L, M, and m are as above and m/ is the value of the X-dial 

 reading corresponding to a salinity of 35°/oo and B is a constant 

 depending on the impedances of the bi-idge not associated with the 

 electrolyte under measurement.^ Where z/^, nu, ma and nii are the 

 X-dial readings at balance corresponding to salinities 5*1, 8-2, Ss and 

 Si respectively, B may be evaluated by sohition of the following 

 quadratic: 



B- 



+ S,Ss{Ss-S,){nu-m.2) 



+ /i 



+ SiSz (S3 — Si ) im.i— m ,, ) m 1 m 3 

 + SiSi {Si - Si ) (mo- //;,3 ) m , m 4 

 + SoSs {S:i — S2) (tn 1 — trii) m2/W3 

 + S.Si {Si - So ) {tn 3 -mi) m.mi 

 _ + S-iSi (S4- S3) (m I - mo) m,mu 



SjSo(So-Si) (m3-m4) (mi + m.o)" 

 + S1S3 (S3 — Si ) (m4 — /no) (m, 1 + m.3) 

 + SiS4(S4-S,) (mo-m3) {mi + nii) 

 + SoS3(S3-S,) (mi-m4) {171. + m,) 

 + S2S4(S4-So)(m3-mi)(mo + W4) 

 L + S3S4(S4-S3)(mi-m,)(m3 + W4). 

 



3 Considering that the adjacent arms of the bridge containing the X- and Y-cells have some small amount 

 of impedance not associated with the electrolytes contained in the cells and that the other two arms of the 

 bridge are each made up of a fixed impedance and a variable impedance, let r be the impedance not associ- 

 ated with the electrolyte in the X-cel! arm, let R be the fixed impedance in the X-dial arm, let E2 be the 



total impedance of the Y-dial arm and let i?4 be the total impedance of the Y-cell arm. Then B= R—r~ 



35 



