11. Clean the reaction chamber between 

 each determination as follows: 



a. Draw 6 ml. of IN lactic acid 

 into the chamber. Lower the Hg to 

 about 25 ml. and shake for a minute. 



b. Discard the lactic acid by 

 displacing with Hg and then repeat the 

 entire cycle using distilled water in 

 place of the acid. 



Ammonia 



We have had most success determining 

 NH3 by Nessler ization after the addition of 

 Rochelle salt to prevent subsequent precip- 

 itation (Wattenberg 1931). Treadwell's Nes- 

 sler reagent has been shown by Wirth and 

 Robinson (1933) to be the most satisfactory 

 of several reagents investigated, since it 

 does not have a completely insensitive 

 region at very low NHj concentrations. 



The determination is carried out as 

 follows : 



1. Remove frozen samples from cold 

 storage and thaw by placing in front of an 

 electric fsin. Do not thaw more than 20 

 samples at a time. 



2. After a sample has warmed to room 

 temperature, clean the cap-glass junction 

 with a jet of distilled water, shake vigor- 

 ously, remove cap and with a 50-milliliter 

 graduated cylinder, measure out 50 ml. of 

 the sample. Discard remainder of sample in 

 the collection vial and pour the measured 

 portion back into the empty vial. 



3. To each of the 50-milliliter sam- 

 ples add 2 ml . of 30-percent solution of 

 potassium sodium tartrate. 



4. Shake all samples thoroughly. 



5. Add 1.6 ml. of ION NaOH to samples 

 and immediately shake. Quickly add 1 ml. of 

 Nessler reagent and shake again. 



6. Exactly 2 minutes after the addi- 

 tion of the sodium hydroxide, read color 

 density in a Fisher electrophotometer using 

 425 B filter. 



7. Convert from density to concentra- 

 tion units by comparing values with those 



of standards which were analyzed with the 



regular samples. 



Nessler reagent: Prepare as follows: 



a. Dissolve 115 gm. Hgl and 80 gm. 

 of Kl in enough water to make 500 ml. 



b. Add 500 ml. of 6N NaOH and 

 mix thoroughly. 



c. Let stand overnight in a 1- 

 liter cylinder. 



d. Decant clear solution into 

 reagent bottle. Discard settlings. 



Chlorophyll 



Chlorophyll was determined by the 

 method of Richards with Thompson (1952) as 

 modified by Cretiz and Richards (1955). The 

 steps involved are as follows: 



1. Add a teaspoon of magnesium car- 

 bonate to each 2-liter sample received. 



2. Store in refrigerator until fol- 

 lowing day. 



3. Filter duplicate 1-liter samples 

 using the millipore apparatus. 



4. When filtration is complete, care- 

 fully cut away the excess filter paper and 

 place the pad containing the chlorophyll 

 sample in a screw-top culture tube. 



5. Add 5-milliliter 90-percent re- 

 distilled acetone to each culture tube. 



6. Triturate samples and allow to 

 stand in the dark for 18 to 24 hours. 



7. If samples cannot be read within 

 this time limit, do not add acetone, but 

 place tubes and samples in a vacuum desic- 

 cator. When samples can be analyzed, add 

 acetone and proceed as in steps 6 and 7. 



8. Again triturate samples in tubes, 

 and centrifuge for 3 minutes at 2,000 rpm. 



9. Read in the Beckman DU spectro- 

 photometer in 1-centimeter Corex cells 

 against a blank of 90-percent redistilled 

 acetone at the following wave lengths — 480, 

 510, 630, 645, and 665 mu. 



10. Make calculations according to 



10 



