initials, of the oceanographcr checking tlie 

 slioct will signify acceptance of tlie data as to 

 accuracy and correctness. 



14-78 The Log Sheet Columns.— The log 

 sheet columns are completed in accordance 

 with the instructions given below. 



14-79 Serial Number. — The serial number 

 is obtainetl from the serial nmnber column 

 of the A-sheet for the station being analyzed. 



14 80 Sample Bottle Number. — The sample 

 bottle munl)ers ai'e obtained from the A-sheet. 

 Tiiey are listed in tlie column headed Oj, under 

 Bottle Numbers. When copying these num- 

 bers from the A-sheet, be sure that they agree 

 with the serial numbers, line for line. 



14-81 1st Burette Reading ml. — Record 

 in this column the burette reading for the first 

 titration of a treated sea water sample. Read- 

 ings are recorded in milliliters to two decimal 

 places. E.xample: 22.92. 



14-82 2nd Burette Reading ml.— Record 

 in this column the burette reading for the 

 second titration of a treated sea water sample. 

 Wlien titrating, the second sample should be 

 not more than ±0.03 ml. different from the 

 first titration to be acceptable. 



14-83 3rd Burette Reading ml.— The column 

 for a third burette reading is used only when 

 50-ml. samples are being titrated. As the sea 

 water sample bottles contain 250 ml., there is 

 only enough sample to make two 100-ml. 

 titrations. With 50-ml. samples the margin 

 of error is twice as great as with the larger 

 samples; therefore, if the first two titrations 

 are not within 0.03 ml. of each other, a third 

 or, if necessary, a fourth titration must be run. 

 In the latter case, record the three best titrations. 



14-84 Average Burette Reading V ml. — 

 Average the values given in the first, second, 

 and third burette reading columns and record 

 the average value in this column. The average 

 burette reading is the value V in the formula 

 for determining the amount of dissolved o.xygen, 

 02 = 56.457VF. 



14-85 Dissolved Oxygen O.ml./l.— The 

 amount of dissolved o.xygen (Oo), expressed in 

 milliliters per liter (ml. /I.) of sea water, is 

 recorded in this column. This value is derived 

 from the formula 02 = 56.45A''F, where A''=the 

 normality of the sodium thiosulfate (NajSjOs) 

 solution and F=tlie average milliliters of 

 sodium thiosulfate solution used in the titration. 

 The latter value is given in the Average Burette 



Reading column. As 56.45 and N remain the 

 same for all samples run on 1 station (unless 

 new solutions have to be made up during the 

 runs), a constant (K) may be determined as 

 follows : 



For 100-ml. samples, X=56.45A'^ 

 For 50-ml. samples, K=2{5QA5N). 

 Thus, when K is determined, the formula 

 becomes 02=KV and the amount of dissolved 

 oxygen can be determined by multiplying K and 

 each Fin the Average Burette Reading column. 



The dissolved oxygen values are recorded on 

 the E-sheet in the 02ml. /I. column under 

 Observed Values. Be sure the serial numbers 

 for these values on the C- and the E-sheets are 

 in agreement. 



14-86 Remarks. — Record in the Remarks 

 column any information that will aid persons 

 analyzing the data after the cruise. If more 

 than one normality determination must be 

 made, use this column to record the data. 



14 87 NORMALITY DETERMINATION.— 

 The determination of the normality of the 

 sodium thiosulfate solution must be made 

 immediately before running the titrations of 

 the sea water samples. Complete instructions 

 for making the blank run and standardization 

 are given in chapter 13. Study thoroughly 

 those instructions before using this column. 



I. Blank Run. — Make three blank runs to 

 determine the value Fj and compute the 

 average Fj. 



II. Standardization of Na^SiOz. — Make three 

 standardization runs of the sodium thiosulfate 

 solution to determine and compute the aver- 

 age F2. 



III. Normality oj NaS-iOi. — Compute the 

 normality of the sodium thiosulfate solution 

 by completing the formula TV (normality) = 



^, " ^r and recording the answer to at least 



three decimal places. 



IV. Dissolved Oxygen Determination. — The 

 formula for determining the dissolved oxygen 

 content of each sample is: 02 = 56.45A^F; where 

 TV is the normality, obtained by III above, and 

 F is the Average Burette Reading. A constant 

 K can be determined as /t = 56.45A'^ for 100-ml. 

 samples and /il=112.9A'' for 50-ml. samples. 

 This factor K may then be multiplied by each 

 value F, given in the Average Burette Reading 

 cohunn, to obtain the dissolved oxygen. The 

 A'^-factor is recorded to at least three decimal 

 places. 



H. O. 607 



145 



