LARD AND LARD ADULTERATIONS 475 



the composition of a mixed lard is probably as truly indicated as by 

 any other single method. 



(7) By determination of product formed by chloride of sulphur. Warren, 

 in the articles already cited, has obtained some interesting results, and 

 our own work has shown that much may be expected of a careful study 

 of this process. Lack of time has prevented a full investigation aud 

 this will be made subsequently. 



(8) Rise of temperature with sulphuric acid. Valuable information re- 

 lating to the composition of a mixed lard may be obtained by a study of 

 rise of temperature of a given volume thereof when mixed with a definite 

 quantity of strong sulphuric acid. The data obtained in our analyses 

 are as follows: 



Rise of temperature with Degrees. 



Lard ..................................................................... 41.5 



Cotton oil ................................................................ 85. 4 



Oleo stearine ............................. . ............................... 20.8 



Lard steariue ............................................................ U7. 7 



Meau rise of temperature with the stearines .................................. &J. ;> 



When the microscope reveals oleo stearine we may take the last num- 

 ber to represent the mean increment of temperature. For an adulter- 

 ant composed of 1.5 parts of cotton oil and 1 part of stearine the mean 

 rise of temperature would be 63. 



The apparent composition of a mixed lard on the above character of 

 the adulterant would be illustrated by the following formula : 



Let =observed rise of temperature for sample. 

 a rise of temperature for lard. 

 &=rise of temperature for cotton oil. 

 c=rise of temperature for stearine. 



=theoretical rise of temperature for the adulterant. 

 #=percentage of adulteration. 



Then 



1.5 b+c 



~2J~ 



This formula applied to the mean rise of temperature observed in 

 Armour's samples gives the following result: 



a?=23.3 per cent. 



Applied to Fail-bank's samples it shows an adulteration of 76.3 per 

 cent. 



9. Calculation from the melting point. The melting point of a fat is 

 often of great value in helping to a correct understanding of its compo- 

 sition, but little reliance can be placed on it for quantitative purposes. 



