ANALYSIS OF BUTTER. 



313 



estimated as barium sulptate, of wkich 233-5 parts represent 

 64 parts of SOj. The solution from which the sulphurous acid 

 has been distilled may be advantageously evaporated to dryness 

 after making alkaline and ignited, and the sulphuric acid esti- 

 mated in this ; the sulphuric acid present is probably due to the 

 oxidation of the sulphite. 



Nitrates may be estimated by one of the methods described 

 under " Water Analysis." If much salt be present, the copper- 

 zinc couple method should be employed. 



Formalin cannot be estimated with any degree of exactitude, 

 as it gradually enters into combination with the proteins present, 

 and only the residue of uncombined formaldehyde, which gives 

 no clue to the original amount, can be determined. 



If adulteration is suspected, it may be of interest to examine 

 microscopically the residue left after removal of the fat ; 

 adulterants, such as starch, mineral matters, etc., which it is 

 alleged have been used, would be thus detected. This form of 

 adulteration is of extreme rarity, but starch is sometimes added 

 to ear-mark margarine. 



The Interpretation of Results.— The President of the 

 Board of Agriculture has laid down that any butter which eon- 

 tains more than 16 per cent, of water shall be presumed, till 

 the contrary is proved, not to be genuine. 



It is advisable always to calculate the solids not fat and salt, 

 not only as percentages, but also as parts per IdO parts of water 

 present. Table LXXVII. will show the characteristics of various 

 classes of butter : — 



TABLE LXXVII. 



The figures given are not intended as absolute limits, but 

 rather as indicating the composition of by far the greater number 

 of samples met with. It is seen that the pickled butters contain 



