316 BUTTER. 



mean molecular weight than the saturated acids : it is probable 

 that oleic acid is the chief representative of the series, and, 

 possibly, higher homologues occur. It is not known with cer- 

 tainty whether acids of other series occur in butter fat. The 

 alcohol present is almost entirely glycerol. 



The pioneer in butter analysis was Otto Hehner, who demon- 

 strated in 1872 that upwards of 5 per cent, of the fatty acids 

 were volatile, and that the quantity of insoluble fatty acids was 

 very much less than that yielded by nearly all other fats. The 

 bulk of the methods at present in use are the legitimate outcome 

 of Hehner's work. Perhaps the only method which is not 

 derived from the first investigation of Hehner is that of von 

 Hiibl, who showed that, by the action of an alcoholic solution 

 of iodine and mercuric chloride, a quantitative addition of halogen 

 could be made to unsaturated glyoerides, but in the simplification 

 of this method Hehner has had a large share. 



Estimation of Volatile Patty Acids. 



Beieliert Process. — Hehner and Angell, after showing that 

 butter contained more butyric acid than was (then) generally 

 supposed, attempted to estimate this by distillation, but finally 

 relinquished the method on account of discordant results, due 

 largely to the bumping of the liquid and the use of too strong an 

 acid. 



Eeiohert proposed to saponify 2 "5 grammes of butter with 



caustic soda and alcohol, evaporate ofi the alcohol, add 50 c.c. 



of water and 20 c.c. dilute sulphuric acid, and to distil 50 c.c. 



in a weak current of air. This method, though Reichert himself 



calls it Hehner's method, is now known as the Reichert process. 



He showed that butters took a constant amount of deci-normal 



alkali for neutralisation, while fats and artificial butters took 



very small quantities (0'3 c.c), and coco-nut oil took about 



3 c.c. ; he proposed 14 '0 c.c. as the mean for genuine butters, 



and 13 "0 c.c. as a limit ; he showed also that mixtures of butter 



N 

 and margarine took quantities of -r alkali equivalent to the 



amount of butter they contained. 



Meissl proposed to saponify 5 grammes of butter-fat in a flask 

 of about 200 c.c. capacity with 2 grammes of caustic potash and 

 50 c.c. of 70 per cent, alcohol, and to drive off the alcohol on 

 the water-bath. The resulting, soap is dissolved in 100 c.c. of 

 water, and 40 c.c. of dilute sulphuric acid (1 to 10) are added 

 and the solution distilled with a few small pieces of pumice ; 

 110 c.c. are collected, filtered, and 100 c.c. titrated with deci- 

 normal alkali. In common with Reichert and the earUer experi- 

 menters, he used litmus as an indicator, but the superiority of 



