1916] AGRICULTURAL CHEMISTRY — AGROTECHNY. 205 



index of the phosphate present in fluorspar slags and affords no guide as to 

 the value of the slag. The phosphatic slag obtained by the use of fluorspar 

 in the manufacture of steel by the open-hearth process has a low citric-acid 

 solubility. The phosphate is, however, completely soluble if the extraction 

 be prolonged for a sufficient time. The phosphates in the slag do not appear 

 to be in combination with silica, but seem to bear a close resemblance to those 

 contained in mineral phosphates. 



Improved methods for fat analysis, E. B. Holland, J. C. Reed, and J. P. 

 Buckley (Massacliusctts Sta. Bui. 166 (1915), pp. 91-138, figs. ^).— This bulle- 

 tin outlines the methods for determining the various chemical constants of 

 oils, fats, and waxes. The methods have been carefully studied and many 

 improvements both in the apparatus and technique introduced. Tabulated 

 data and supplementary notes of value in the interpretation of analytical re- 

 sults, together with formulas for calculating certain other constants, are in- 

 cluded. 



A new procedure for the determination of the acetyl number is described 

 as follows : Into a 300 cc. Erlenmeyer flask are brought 5 gm. of fat together 

 with 10 cc. of acetic anhydrid. The flask is connected with a spiral or other 

 form of reflux condenser and heated in a boiling water bath for from 1 to 1.5 

 hours. After acetylating, the condenser is removed from the flask and suffi- 

 cient ceresine added to form a solid disk with the fat when chilled in cold 

 water. With the flask still in the water bath 150 cc. of boiling water is added, 

 with as little disturbance of the fat layer as possible. The flask is then re- 

 moved and the contents rotated vigorously to dissolve occluded acetic acid. 

 The ceresine fat is then solidified by immersing the flask in cold water, after 

 which the solution is decanted through a dense filter, care being taken not to 

 break the insoluble cake. Another 150 cc. of boiling water is added, thor- 

 oughly agitated, heated a few minutes in the bath, cooled, and decanted. 

 The process is repeated iintil the final filtrate gives a decided color with two 

 or three drops of tenth-normal alkali, using phenolphthalein as indicator. The 

 filter and inverted flask containing the cake of ceresine fat are allowed to 

 drain in a cool place until practically dry. The small particles adhering to 

 the filter are then scraped into the flask, the inner portion of the filter paper 

 extracted in a small beaker with three successive 20 cc. portions of boiling 

 alcohol, and poured into the flask. Fifty cc. of alcoholic potash and several 

 glass beads are then added, the flask is connected with a suitable form of 

 reflux condenser, and the solution boiled on the water bath until saponifica- 

 tion is complete. After cooling the solution to 60° C. it is titrated with half- 

 normal hydrochloric acid, using 1 cc. of phenolphthalein or cotton blue, as indi- 

 cator. The alcoholic mixture is again brought to boil to free any alkali 

 occluded in the ceresine, and retitered if necessary. Several blank deter- 

 minations should be run with every series of tests, under precisely similar 

 conditions as to time and treatment except that the ceresine may be omitted. 

 Every lot of ceresine, however, must be tested and be free from soluble matter 

 and not assimilate any alkali on saponification. The difference between the 

 titration of the blanks and that of the excess alkali in the test is the acid 

 equivalent of the fat after acetylation, which is calculated to milligrams of 

 potassium hydroxid per gram of fat. 



For the determination of unsaponifiable matter the following modified pro- 

 cedure is described: Five gm. of fat are completely saponified in a 300 cc. 

 Erlenmeyer flask with 75 cc. of alcoholic potash and 25 cc. of alcohol under 

 a reflux condenser. The solution is then transferred to a 250 cc. Griffin beaker 

 and the flask rinsed several times with hot alcohol. The alcohol is evaporated 

 54530°— No. 3—16 2 



