chlorates. 
6 BULLETIN 1389, U. 8S. DEPARTMENT OF AGRICULTURE } 
and titrate with 0.1 N silver nitrate, using as an indicator potassium 
chromate or the sodium arsenate formed in the solution. 
In either case a blank determination on the reagents used should 
be made. This titration gives the sum of the available and chloride 
chlorine. The percentage of chloride chlorine present is found by 
deducting the percentage of available chlorine from this value. 
TOTAL CHLORINE 
The following method, which is described by Pattinson (8), was 
used to determine the total chlorine: 
Treat with sulphurous acid a 50-cubic centimeter aliquot of the 
solution prepared for the determination of available chlorine and heat 
the mixture to boiling, to reduce chlorates and expel the excess sul- 
phurous acid. Add two or three drops of nitric acid to insure com- 
plete removal of the sulphurous acid. Cool the solution, neutralize 
with calcium carbonate, and titrate with silver nitrate, as outlined in 
the method for chloride chlorine. 
This method gives total chlorine. The difference between the 
available chlorine plus the chloride chlorine and this result repre- 
sents the chlorine existing in a higher oxidized form, probably as 
CALCIUM, MAGNESIUM, IRON, ALUMINUM, AND SILICA 
The following method was used to determine the calcium, magne- 
sium, iron, aluminum, and silica: 
To 2 grams of the sample in water, in a 250-cubic centimeter 
beaker, add 25 cubic centimeters of strong hydrochloric acid (specific 
gravity 1.184) and 50 cubic centimeters of 3 per cent hydrogen per- 
oxide solution. Evaporate this solution on a steam bath, bake on 
a hot plate for one-half hour to dehydrate silica, take up in dilute 
hydrochloric acid (1+9), and filter off the silica. Ignite the pre- 
cipitate and weigh as silica (SiO,). 
Add ammonia in slight excess to the filtrate and washings, and boil 
the solution until the cdor of ammonia is barely perceptible. Filter 
the combined hydroxides of iron and aluminum, and collect the filtrate 
and washings in a 250-cubic centimeter volumetric flask. Ignite the 
precipitate and weigh as iron and aluminum oxides (R,O,). 
Dilute the filtrate to mark, mix, and precipitate the calcium in the 
usual manner with ammonium oxalate, using a 50-cubic centimeter 
aliquot and reprecipitating. Dissolve the precipitate in dilute sul- 
phuriec acid (1+3) and titrate with 0.2 N potassium permanganate. 
Report the result as calcium oxide (CaQ). | 
Determine magnesium in the combined filtrate and washings from 
the calcium determination by precipitating with disodium phosphate 
solution, igniting, and weighing as magnesium pyrophosphate 
(Mg.P,O,). ; 
CARBON DIOXIDE ; 
Expel carbon dioxide in an evolution flask, passing the gas barons 
wash bottles containing potassium iodide solution, and absorbing the 
carbon dioxide with standard barium hydroxide solution. Titrate 
the excess barium hydroxide with standard hydrochloric acid. The 
apparatus used (fig. 1) consists of the following: An evolution flask. 
A), connected with a soda-lime tube (B), dropping funnel (@), and) 
Kjeldahl trap (D), wash bottles (£), containing glass beads and) 
