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Lard Oil.

Mr. Editor.

Considerable anxiety prevails among our people in relation to the large quantity of lard oil now manufactured and sold for olive oil. The practice, I learn, is to obtain bottles which formerly contained olive oil, and by mixing one-half of clarified lard oil with olive oil, which arrives from France in bulk, an article is produced which readily sells for olive oil, and by many of our people is used as such. It is, also presumed, that some of this lard oil has been exported for the purpose of this admixture. As this is a serious cause of uneasiness among those who have conscientious scruples, and who use great quantities of sweet oil for domestic purpose: I felt some interest in having the two oils chemically tested for the purpose of ascertaining and detecting any admixture of vegetable and animal oils. Professor Reed of the College of Pharmacy, having kindly offered to apply the necessary tests, Mr. Joseph Dreyfous and some other gentlemen accompanied me to the College, where experiments of an undoubted character were made on the several oils obtained for the purpose. It was satisfactorily ascertained that pure olive oil congeals at the temperature of 36 degrees of Fahrenheit’s Thermometer. Lard oil requires a much greater degree of cold to produce a congelation, and when mixed with olive oil in any quantity, it prevents the congelation at that temperature.

This test may be applied by breaking a few pieces of ice, and placing them in a glass with water and inserting a phial containing the oil to be examined into this ice and water: the ice when melting, reduces the temperature of the water to 32 degrees, sufficiently cold for the experiment.

The congelation which is only partial, is caused by the separation of the principal substances which form olive oil; they are named elain and stearin: the elain is fluid at low temperatures, while the stearin is solid. For the purpose of estimating the purity of olive oil by the percentage of stearin it may contain, the oil is subjected to a temperature of 20 degrees, which may be done by mixing one pound of snow or pounded ice, with half a pound of common salt in a basin, place a small cup with the oil in the mixture, allow it to remain about half an hour, then take the congealed mass and press it between blotting paper, the elain will be absorbed, the stearin remains, which is a solid, at about temperature of 60. Pure olive oil tested by the above method, yields

72 per cent. elain,
28 per cent. stearin.

Another test more important, because more practicable, consists in taking a solution of mercury in nitric acid, and mixing it with the olive oil, in the proportion of one part of the nitrate of mercury in solution, with forty-eight of oil, shaking or stirring it every half hour; if pure, in seven hours the oil will assume the consistence of butter, and in twenty­ four hours it will give a considerable resistance to knife or spoon, or any hard substance—somewhat of the consistence of hard pomatum.

When any animal oil is present, a coagulation takes place sooner, but it is a coagulation of the animal or fat; the olive oil separates and does not mix with the coagulated mass. To prepare the solution of mercury, take 120 gains of mercury and 150 grains of nitric acid of the specific gravity of 1·35; this is y about the medium kept in drug stores, and contains 48 per cent. real nitric acid; 100 grains should, when mixed with water, dissolve 44½ grains of marble, it is essential to the test that the acid should be about the above  strength; the mercury and acid are placed in a clean Florence oil flask; heat is applied with a spirit lamp, or it is placed near the fire until the mercury is dissolved; this fluid should be kept in a glass-stopped bottle, it is called after the name of the inventor, Paulett’s test liquor. A good proportion to test with, would be 12 drops of this liquor to 14 spoonfuls of oil, at a temperature of 68 degrees, this is stronger than what is requisite, but will give a result in a shorter time.

This test was made on Lucca and and Leghorn oil, and we found it perfectly pure. We have also ascertained, that in the above named parts of Italy, that lard oil would cost more than olive oil, and consequently, would be of no advantage to the shipper to be mixed; all that we have to guard against, is the oil bottled in this country, and perhaps at Marseilles. Bordeaux oil is considered as pure as Leghorn or Lucca. This last test is most certain, as determining the purity of olive oil, from all kinds of oil, vegetable or animal.

I have no doubt, that you will consider this communication of sufficient importance to put our brethren in this country on their guard, and remove any uneasiness or apprehension which exists on the subject.

Very truly yours,

REV. Mr. Leeser.

NOTE.—We call the earnest attention of our readers to the above highly interesting communication of Judge Noah. When first we heard of the rumoured admixture of the vegetable oils with animal substance, we hardly gave credence to the report, under the impression that it would not be to the interest of the European manufacturers of these articles to adulterate them with substances which they have to import from abroad. But since the fact seems now to be established, we trust that before any doubtful oils are used, they will be subjected to the tests proposed above. Of course, not being a scientific man we cannot spear of our own knowledge of the accuracy of the tests proposed; but we have no doubt that they will furnish an approximation to, if not even an entire knowledge of the quality of the substances to be tested.

Would it not be well to appoint, under authority of the various Synagogues in France and Italy, inspectors whose duty it would be to seal all the oils which are to be exported for the use of the Jews abroad? In this way only could we avoid all danger of fraud, as the certificate and seal of such inspectors would prove beyond a doubt that no adulteration had taken place. We invite the attention of Sir Moses Montefiore, and our other influential readers in England to this subject, in the hope that they may be able to do something towards carrying out our suggestion.

Ed. Occ.