LARD AND LARD ADULTERATIONS. 521 



A plate of chemically clean glass was covered with tilm of water, a drop of the 

 melted fat was dropped upon the plate, and the patterns noted. 



A portion of the fat was saponified with an equal weight of sodic hydrate dissolved 

 iu water, and the time occupied in saponifying noted. 



A portion of the fat was treated with a solution of hyponitric acid and sulphuric 

 acid, and the time necessary for the solidification of the elaidine noted. 



In all the above parallel experiments were made under exactly the same circum- 

 stances in every respect. 



W. HOSKINS.' 



The above methods rests chiefly on the percentage of insoluble residue 

 after treating the fat with a mixture of ether and alcohol as described. 



METHOD OF J. M. HIRSH.* 



I melt the sample and dissolve it in purified naphtha, leaving it there at rest at 

 a temperature of ahout 70 F. for twelve hours, when added stearine or tallow 

 will deposit, while pure lard will show no deposit, or barely a trace. The amount of 

 the deposit increases considerably in the next twelve hours in a mixture with stea- 

 rine, but little iu pure lard. The test being made iu a graduated tube, the propor- 

 tions can be read off without possible error by washing, weighing, or measuring. 

 After the time mentioned the solids of the lard deposit. The remaining solution I 

 treat with nitric acid, which renders crystalline the animal oil (producing elaidiue), 

 but leaves the cotton-seed oil a colored liquid. 



As a rule the melted sample has minute libers of cotton floating when it is contam- 

 inated with cotton-seed o^l ; this test is simple and infallible; for this reason I omit 

 to mention other corroborative tests. 



J. M. HIRSH. 



FURTHER REMARKS BY ,T. M. HIRSH.t 



Lard will give a reaction of elaidine as well as cotton-seed oil, but a time amply 

 sufficient to make elaidiue from lard or any animal oil must bo greatly exceeded to 

 get the same result from cotton-seed oil. If linsed oil or cotton-seed oil, or the two 

 mixed, are boiled for five minutes with a fume of nitric acid, there will bo no ap- 

 parent change except that they become colorless ; they will have to boil an hour or 

 two before separation takes place; in half an hour or so they would become a s>lid, 

 like steariue. Animal oils treated iu the same manner will be solidified and con- 

 verted into elaidine in five minutes. In applying the elaidine test he first took all 

 the crystals out of the solution, then drew off from the tube all the oleiu and the 

 benzine, put the nitric acid into that liquid, and heated it ; the benzine evaporated 

 quickly ; the heating was continued for a few minutes longer, and then it was allowed 

 to cool; the crystallized deposit of elaidine he considered as from animal oils, and 

 what was left, after withdrawing the liquid, he considered was from an admixture of 

 some other oil. In a lard rendered at a high pressure of steam there would bo a 

 greater amount of stearine than in one rendered at a low pressure, the original ma- 

 terial being the same. If lard is rendered and run into a large reservoir holding, aay^ 

 250 tierces, and there allowed i;o stand for a time, the lard from the bottom of that 

 reservoir would contain a greater amount of steariiie than would that drawn from 

 the top. There would be a great deal of difference. The heaviest lard would settle 

 iu the reservoir. The difference in the stearino would not be more than, if so much 

 as, 2 to 4 per cent, of chemically pure steariue. A good deal would depend on the 

 depth of the tank or reservoir and on the temperature maintained in the lard. H a 

 thinks in lard drawn from the top or bottom of such a reservoir there would not 

 be as much difference in the stearine as he has found in the lard delivered him by 



* Op. cit., p. 154. t Op. cit., p. 155. 



