

DAIRY PRODUCTS. 61 



placed in a basin with hot water, and kept boiling for a considerable time, 

 until on adding water not the faintest turbidity occurs. Ten ounces of 

 water are added, the evaporation continued (just short of boiling) until 

 all traces of alcohol are dissipated. The contents of the flask are then 

 made np to 7 ounces with nearly boiling water, and a good fitting cork 

 having been introduced through which j ust passes a tube 2 feet long and 

 ending in a small funnel, 5 grams of full strength sulphuric acid are poured 

 in down the tube followed by some water. The whole is then agitated 

 with a circular motion until the soap, which rises suddenly, is changed 

 into a perfectly clear and transparent stratum of fatty acids. The flask 

 and contents are then cooled down to 40 F., till a perfectly solid cake 

 of fatty acid forms. A few drops of cold water are run in to wash the 

 tube, and, the cork having been removed, a small piece of fine cambric 

 is placed over the mouth of the flask, held in situ by an ordinary India- 

 rubber ring. The fat cake is caused to detach itself from the sides of 

 the flask by a gentle movement, and then the filtrate is decanted, with- 

 out breaking the cake, into a litre test mixer with a good stopper. 

 About an ounce of cold water is poured into the flask through the cam- 

 bric, and the whole cake and flask rinsed out by gently turning round, 

 and the washings added to the filtrate. Six ounces of water at 120 F. 

 are now added through the muslin, which is then quickly detached, 

 and the cork and tube inserted ; the whole again heated, this time to 

 200 F., and kept constantly agitated with a circular but not a jerky mo- 

 tion for five minutes. This agitation so divides the fat that it almost 

 forms an emulsion with the water, and is the only means of thoroughly 

 and rapidly washing fatty acids without loss. In practice no butyric 

 acid comes off at 200 F., but any trace that might do so is caught in the 

 long tube. The cooling and filtering are then again proceeded with as 

 above described (the filtrate being added to the contents of the test 

 mixer), and the washings are repeated alternately, cold with 1 ounce, 

 and hot with G ounces of water, until they do not give the slightest 

 change to neutral litmus. After thoroughly draining the residual cake 

 by letting the flasks stand upside down for some time, the cambric is re- 

 moved and the flask is laid on its side in the drying oven, with a sup- 

 port under the neck, until the acids are thoroughly fused, when they 

 are poured while hot into a tarred platinum capsule, dried and weighed. 

 The film of fatty acid still remaining on the flask is rinsed out with 

 ether and dried in a small weighed beaker, and the weight added to 

 the whole. If any drops of water be observed under the fatty acids in 

 the capsule after an hour's drying the addition of a few drops of abso- 

 lute alcohol will quickly cause them to dry off. If any trace of fat is 

 on the cambric it should be also dried and extracted with ether, but 

 with care not to break the cake at the last pouring off this does not 

 occur. 



The process is absolutely accurate, and the merest tyro cannot make 

 any loss so long as he does not deliberately shake the melted acids 



