"20. DETERMINATION op ALDEHYDES. 



"(a) Preparation of reagent. Eighty cubic centimeters of a saturated solution of 

 sodium disulphite are mixed with a solution of 0.12 gram of fuchsin iu about 800 cc 

 of water, 12 cc of sulphuric acid added, the solution thoroughly mixed, and diluted 

 with water i<) 1 liter. 



" (b) IMcrmiinttion.A portion of the sample is diluted with water, or strengthened 

 with aldehyde-free alcohol until it contains 50 per cent of alcohol by volume, and 

 25 << of tliis solution are treated with 10 cc of the reagent, and allowed to stand 

 twenty minutes. At the, same, time 25 cc of a solution of 0.05 gram of acetic alde- 

 hyde in 1 .()()() cc of 50 per cent alcohol are treated in thesaine manner and allowed to 

 stand the same length of time. The relative intensity of the colors of the two 

 solutions is then determined by means of a colorimeter, and from the figure thus 

 obtained the weight of aldehyde is estimated as acetic aldehyde, and calculated to 

 p reiMitage of the original liquor. 



"21. DETERMINATION OF ETHEREAL SALTS. 



After the determination of the volatile acids, the neutralized distillate is trans- 

 ferred to a Ilask connected with a reflux condenser, treated with 25 cc of tenth nor- 

 mal sodium hydroxid, and boiled one-half hour. The flask and contents are then 

 cooled. IT) cc of tenth normal hydrochloric acid added, and the excess of acid 

 titrated with sodium hydroxid, using phenolphtalein as indicator. The number 

 of cubic centimeters of tenth normal alkali used in this titration, multiplied by 

 0.00*8, is equal to the weight in grams of ethereal salts (calculated as ethyl acetate) 

 in the volume of liquor taken for the determination." 



OPTIONAL METHOD OF DETERMINING PHOSPHORIC ACID IN SOILS. 



NOTK. The following method, devised by Mr. Goss, was recommended as an 

 optional method by the association in 1895, but was not ordered printed with the 

 official methods. A synopsis of it is printed here for the convenience of analysts: 



"Ten grams of the air-dried soil, passed through a sieve of one millimeter mesh, 

 are placed in a small Kjeldahl flask marked at 250 cc. From 20 to 30 cc concen- 

 trated sulphuric acid and approximately 0.7 gram yellow oxid of mercury are added, 

 the contents of the Ilask well mixed by shaking, and oxidized over the open flame, as 

 in the determination of nitrogen, for an hour. After cooling, about 100 cc of water, 

 5 CC of concentrated hydrochloric acid and 2 cc of concentrated nitric acid are added, 

 and the, mixture reboiled to oxidize the iron, cooled, and the volume completed to 

 one-fourth of a liter with water, and the contents of the flask filtered through a dry, 

 folded filter paper. One hundred cubic centimeters of the filtrate are placed in a 

 Ilask of about 450 cc capacity, strong ammonia added until a permanent precipitate 

 is formed, which is dissolved by the addition of about 7 cc of nitric acid, and the 

 mixture boiled until clear. The flask is removed from the flame and cooled at room 

 temperature (<>' exactly two minutes, 75 cc rnolybdate solution added, and the flask 

 placed in a water hath kept at 80 for 15 minutes, shaking vigorously four or five 

 tunes meanwhile. After removing from the bath, the flask is allowed to stand for 

 ten minutes until the precipitate has settled, and the supernatant liquid is poured on 

 to the lilter paper under pressure, the precipitate being partially brought upon the 

 paper. The flask and precipitate are thoroughly washed with ammonium-nitrate 

 so.ution, the precipitate either by decautation or in the filter paper. The flask 

 is then placed under the filter, the precipitate is dissolved in ammonia, and the 

 phosphoric acid estimated by the usual processes. Details of the manipulation are 

 given in Bulletin No. 43 of the Division of Chemistry, pp. 58-60." 



