533 



Detection of margarine in butter ( Dntfsche }fnllcrci Zcilvnfj^ 1891, Ko. 9, 

 p. 120). — According to the method of JJochaiiy {PhanuazcvtlHche Zci- 

 inng, 1890, p. 518), 15 c. c. of clarified fat are dissolved in a graduated 

 glass cylinder, witli 15 c. c. toluol, and 50 c. c. absolute alcohol added. 

 The solution is then heated to 50° (J. and well shaken. If the fat con- 

 sists to a considerable extent of margarine the solution at once becomes 

 cloudy ; in case of mixtures this cloudiness or precipitation shows itself 

 first when the solution is cooled to 10° C. A butter mixture containing 

 10 per cent margarine gave a precipitate occupying 10 c. c, but no 

 constant relation was found between the percentage of margarine and 

 the volume of the precipitate. 



According to II. Brnlle {Compt. ren(J., 112 (1891), p. 105), a25-per cent 

 solution of silver nitrate in 95 per cent alcohol gives cliaracteristic 

 colors with the different oils, and is applicable for the detection of mar- 

 garine in butter; 12 c. c. of the filtered fat and 5 c. c. of the silver 

 solution are mixed in a test tube, the tube is dipped in boiling water, 

 and the change of color observed. Pure butter gives no color with the 

 re-agent, but a mixture of margarine and butter gives a brick-red color. 

 The color is very pronounced with butter containing 10 per cent of 

 margarine, but some practice is required to detect less than 5 per cent. 



Examination of butter with the oleofractometer {Deutsche Mollcerei-Zei- 

 tung, 1891, No. 9, j;. 120).— Jean {Bull. Soc. Chim., 1890, _p. 105) recom- 

 mends the use of the oleofractometer as constructed by himself and 

 Amagat. The instrument is adjusted bj^ means of a normal oil at 45° 

 C, and the examination of samples of butter is made at the same tem- 

 perature. According to his observations the refraction for pure butter 

 Is — 35°, while that for pure margarine is — 15°. 



Viollette* gives the index of refraction for butter as varying from 

 — 33° to — 28°, and that for margarine from — 15° to — 8°. 



Depaire {Kei\ intern, des Falsljic., 1890, 4, p. 05) found the refraction 

 of numerous samples of butter made during winter and summer to 

 vary between — 35° and — 39°, and that of different kinds of margarine 

 between — 9° and — 17°. Mixtures of pure natural butter (index 38°) 

 and oleomargarine (index 10°) in different proportions showed the fol- 

 lowing refractions : 



Percent of. niargariae 10 20 .30 40 50 GO 70 80 100 



Index of refraction 38° 36° 34^^ 31^ 29° 26° 21° 18° 15° 10° 



The presence, although not the nature, of a foreign fat in butter 

 would, according to these experiments, seem to be indicated with con- 

 siderable certainty by the Jean-Amagat oleofractometer. 



Detection of cocoanut butter in cows' butter, F. Jean {Monit. Scieiit., 1890, 

 4, .ser. 4, IIHJ; Deutsche Molkcrei-Zcitung, 1891, iVo. 9, p. 121). — Pure 

 cocoanut butter, the manufacture of which is said to be on the increase, 

 closely resembles butter made from cows' milk. Unlike other vego- 



• See Experiment Station Record, Vol. II, p. 465. 



