40 ANALYSIS AND ADULTERATIONS OF BUTTER. 



It would be of considerable interest to know the propor- 

 tions of stearin, palmitin, and olein contained in butter and 

 other fats, but there are no methods of separating these 

 substances or the acids they yield -syith anything like quanti- 

 tative precision. Moreover, if it were reaUy possible to 

 separate them the results would be only of secondary 

 importance, and in no way superior to the indications 

 afforded by the melting point, for mixtures of fats of high 

 melting point and of liquid oils could easily be nM,de con- 

 taining stearin, palmitin, and olein in the same proportion as 

 these glycerides occur in butter. Tests founded upon such 

 proportions would be quite as fallacious as the specific gravity 

 of milk, if used alone, and not as a corroboration to 1;he 

 results obtained by some more trustworthy method. It 

 should here be remarked that _it_is_.by.. no means c ertain 

 w hether butter-fat really dsSS_£2B-.^ii „either .stearin_OT jthg 

 ^ordinary B9raaal-.QleiJl-,_ Stearin seems to be entirely absent, 

 and the liquid glyceride present may weU be a butyrolein, 

 such as given by Bromeis. Dr. Tidy, in a paper read before 

 the Society of Medical Officers of Health, denied that butter 

 contained "more than traces of palmitin, stearin, or olein. 

 But Dr. Tidy does not state what butter, in his opinion, 

 consists of, or upon what grounds his statement is based. 

 Certain it is, thatjf there is any steari n its quan tity must he„ 

 infinitesimally smaUj as the fatty acids, either when_ crys- 

 tallized from alcohol or precipitated fractionally by acetate of 

 magnesia, do not yield crystals of the composition of stearic 

 acid or a precipitate of stearate of magnesia. But by the 

 former of these methods a beautiful white acid, crystaUising 

 in tufts of silky needles, agreeing in physical properties, 

 solubility, etc., with jahnitic^ acid, may be obtained, and 

 this acid seems to constitute a large proportion of the 

 insoluble fatty acids of butter-fat. 

 The magnesium salt of this acid was fpund to contain 



