INFLUENCE OF ROSIN ON FATTY SUBSTANCES. 
325 
be swallowed, and the infusion being stirred up, the whole 
is taken, liquid and powder, at two or three draughts, at short 
intervals, being washed down by cold water and lemon juice. 
To promote the operation, tea (with sugar or milk) may be 
taken. In three or four hours if the remedy has not operated, 
a dose of castor oil or a saline purgative should be admin- 
istered. 
ART. LXXIII. — ON THE INFLUENCE OF ROSIN IN PREVENT- 
ING THE OXIDATION OF FATTY SUBSTANCES. 
By Prof. Olmstead. 
Economic Science. — The report in the New York Herald 
of the proceedings of the American Scientific Convention, 
now in session at New Haven, embraces some remarks by 
Prof. Olmstead, on the subject of mixing lard and rosin to- 
gether, which, notwithstanding its homely sound, will be 
found of no little novelty and practical interest. Prof. O. 
accidentally observed that rosin added to lard, gives it a de- 
gree of fluidity not before possessed by the lard, and also 
prevented the latter forming those acids which corrode me- 
tals, copper and brass for example. We extract the follow- 
ing account of some of the properties and applications of 
the mixture : 
The best proportions are by weight — lard three parts, ro- 
sin one part. If the rosin be added in fine powder, and the 
mixture well stirred, (without the application of heat,) it 
softens and so nearly approaches a fluid, as to run freely 
when taken up on the stirring-rod, at a temperature of 72 
degrees. On melting the mixture, and setting it aside to 
cool, the following changes take place : — at 90 degrees it 
remains transparent and limpid ; at 87 degrees, a pellicle 
begins to form on the surface, and soon after it begins to 
grow slightly viscid, and as the temperature descends, it 
26 
