428 FOODS AND FOOD ADULTERANTS. 



The exports from 1873 to 1888 are shown by the following numbers 



If we take the percentage of cotton oil in the compound lard at 40, 

 the total weight of oil used in manufacturing mixed lard is 120.000,000 

 pounds. 



In addition to this, large quantities of cotton oil are used for salad 

 dressing and culinary operations and in the manufacture of a substitute 

 for lard, cotoleue, which contains no hog grease whatever. 



METHODS OF ANALYSIS EMPLOYED. 



The processes employed in conducting the analytical work, the re- 

 sults of which follow, will now be briefly described. 



METHOD OF TAKING THE SPECIFIC GRAVITY. 



(a) By the picnometer.Two kinds of specific gravity flasks have been 

 used in the determinations of the specific gravities, as represented in 

 Fig. 17, viz, a plain flask with a stopper having a capillary perforation 

 and a flask carrying a stopper to which is attached a delicate thermom- 

 eter. If the specific gravity is to be taken at a temperature of 100 or 

 that of boiling water, the plain flask. is preferable ; if, however, it is to 

 be taken at some temperature below that point, for instance, 40, the 

 flask with the thermometer is used. The manipulation in both cases is 

 the same. 



(b) Graduation of the flasks. The flasks, having been cleaned, are 

 rinsed with alcohol and ether and thoroughly dried, care being taken 

 that the ether and alcohol vapors are removed from the interior of tin 1 

 flask. Tbe flask, after it is cleaned, should be handled with dry fingers 

 or with forceps. The stopper having been inserted, the dried and 

 cleaned flask is weighed empty at the temperature of the balance room. 

 If the flask be wiped with a silk handkerchief or towel before weighing 

 it should be allowed to stand fifteen minutes in the balance before the 

 final weights are taken. The flask is now filled with recently boiled dis. 

 tilled water which, to avoid mixing with air, has not been shaken. It 

 is placed in a bath of distilled water in a vessel with a flat bottom. 

 The b:i th should contain as much water as is possible to avoid flowing 



