Lal ANNUAL REPORT 
Transfer the sample to a 300 cc. beaker, add 30 cc. of water, cover with 
a watch glass, add 10 cc. of hydrochloric acid anda little nitric acti. 
Boil till all the soluble matter is dissolved and all the carbon dioxide 
expelled. Wash off watch glass and dilute to about 150 cc. with water 
previously boiled. Add ammonia slightly in excess and heat to boiling. 
If the insoluble residue is low and it is not desired to weigh the insoluble 
matter it is not necessary to filter it off. The calcium oxalate is precipi- 
tated in the boiling hot solution as usual by the addition of 40 cc. of a 
hot solution consisting of 20 cc. of concentrated ammonium oxalate solu- 
tion and 20 cc. of water. Stir for several minutes and let settle for five 
minutes. 
Decant the supernatant solution through an ashless filter, add 40 cc. 
of hot water, decant, add another portion of hot water and decant for the 
third time. Now transfer the precipitate to the filter and wash three or 
four times with hot water. To determine whether or not the precipitate 
has been washed sufficiently, catch a few cc. of the last filtrate on a watch 
glass, add a drop of sulphuric and one drop of potassium permanganate 
solution. If the liquid shows a strong red color the washing is finished, 
if the color is discharged further washing is necessary. ‘The calcium 
oxalate is now washed back into the beaker in which it was precipitated, 
using hot water and diluted to about 200 cc. if necessary. Place the 
beaker under the funnel and run through the filter into the beaker 30 cc. 
of dilute sulphuric acid (1 volume of acid to 3 of water). Wash the 
filter thoroughly with hot water and stir the contents of the beaker while 
running in the acid. Heat liquid to about 80° C. and titrate with the 
permanganate solution to a faint pink color which should not disappear 
for two minutes. ; 
The potassium permanganate solution should not be standardized 
against iron or ammonium ferrous sulphate, but against calcite checked 
repeatedly by the gravimetric method of calcium determination. 
R. Kk. Meade* proposes to keep the iron and alumina in solution by 
the addition of 5 per cent. oxalic acid, the calcium being precipitated by 
ammonium oxalate and determined volumetrically with a standard per- 
manganate solution. The results have been found by Meade to be very 
satisfactory. , 
Method 2,—The acid alkali methods, owing to their rapidity and 
simplicity, are frequently made use of, but great caution is necessary in 
their use, and the results should be carefully checked gravimetrically from 
time to time owing to the fact that these methods are subject to errors. 
Larger amounts of alumina and iron influence the results most decidedly. 
S. B. Newberry** proposes the following working method: 
Prepare a n/5 solution of hydrochloric acid and a n/5 caustic soda 
solution, standardizing with pure Iceland spar, which has been analyzed 
*“Oement and Engineering News,’ June, 1903. 
*k “Tbid,’ March, 1903. 
