LARD AND LARD ADULTERATIONS. 415 



characteristic of great value. The melting point of the fat of the swine 

 varies with the part of the body from which it is taken. The fat from 

 the foot of the swine appears to have the least melting point, viz, 35.1. 

 The intestinal fat seems to have the highest, viz, 44. In fat derived 

 from the head of the animal the melting point is found to be 35.5, 

 while the kidney fat of the same animal shows a melting point of 42.5. 

 In steam lards, representing the lards passed Uy the Chicago Board of 

 Trade, the melting point for ten samples was found to vary between 

 29.8 and 43.9. In general it may be said that the melting point of 

 steam lards is about 37 which is the mean of ten samples examined. 

 In pure lards derived from other localities the melting point was also 

 found to vary. A sample of lard from Deerfoofc Farm, Southborough, 

 Mass., was found to have a melting point of 44.9, while a pure lard 

 from Sperry & Barnes, Kew Haven, Conn., melted at 39. The mean 

 for eighteen samples was 40.7. While the melting point can not be 

 taken as a certain indication of the purity of a lard, nevertheless a wide 

 variation from 40 in the melting point of a lard should lead at least to 

 a suspicion of its genuineness, or that it was made from some special 

 part of the animal. Perhaps one reason why the melting point has not 

 been more highly regarded by analysts is because of the unsatisfactory 

 method of determining it; but when it is ascertained by the method 

 used in these investigations it becomes a characteristic of great value. 



(c) Color reaction. The coloration produced on pure lard by cer- 

 tain reagents serves as a valuable diagnostic sign in the analysis of 

 lard and its adulterations. Various reagents have been employed for 

 the production of characteristic colors in fats, but of these only two are 

 of essential importance. They are sulphuric and nitric acids. Pure 

 lard, when mixed with sulphuric and nitric acids of the proper density, 

 as indicated hereafter, give only a slight color which varies from light 

 pink to faint brown. The variation produced in the colors by pure 

 lards is doubtless due to the presence in various quantities of certain 

 tissues of the animal other than fat. For instance, a variation in the 

 amount of gelatinous substance mechanically entangled with the lard 

 or of the tissues composing the cells in which the lard was originally 

 contained would be entirely sufficient to account for the slight differ- 

 ences in color produced by lards of known purity. It might, therefore, 

 be difficult to distinguish accurately between a pure lard containing a 

 considerable amount of other tissues from the animal and one which 

 contained a small amount of adulteration. The coloration produced, 

 therefore, by the acids named should not be relied upon wholly in dis- 

 tinguishing pure and adulterated lards; but the character of such 

 coloration should be carefully noted in the analyst's book, In the steam 

 lards examined some of the remarks describing the coloration produced 

 are as follows : 



"Trace of color," u faint pink," "bright pink," " light red," "yellow- 

 h," etc. For pure lards of miscellaneous origin some of the descrip- 



