DAIRY PEODUCTS. 



75 



The quantity of stearin in butter fat is small compared with that in 

 lard, tallow, &c. On this difference of constitution Professor Scheffer 1 

 has based a method of analysis. 



A mixture is made containing 40 volumes of rectified amyl-alcohol 

 and 60 volumes ether of .725 specific gravity at 15 0. One gram of 

 butter fat is dissolved in 3cc. of this mixture at 26 to 28 0. On the 

 other hand, 1 gram lard requires 16cc. of the solvent, 1 gram tallow 

 50cc., and 1 gram stearin 350cc. 



For the experiment take a test tube of 12cc. capacity and place in it 

 1 gram fat, add Sec. of the amyl-alcohol ether mixture. After tightly 

 corking the tube puc it in a water bath of 18 0. and with frequent shaking 

 bringing the temperature to 28 0. If the butter is pure the solution be- 

 comes perfectly clear at this temperature. If not clear more of the 

 solution can be ran in out of a burette and the additional quantity re- 

 quired will be some indication of the quantity or quality of the adul- 

 terant which has been used. 



According to Scheffer, mixtures of pure butter and lard gave the 

 folio wing data: 



A trial of this method has shown that it is capable of giving valuable 

 qualitative indications in respect of the purity of the sample under 

 examination. I believe it is the best simple test aside from the micro- 

 scopic examination capable of general application which has been pro- 

 posed. 



The easiest method to secure a certain weight of fats is to melt them 

 and measure out from a pipette 1 cubic centimeter of each. The fats 

 which do not melt easily should be stirred up thoroughly with a wire, 

 while the temperature is raised from 18 to 28 C. 



(3) Odor of the burning grease. 2 



(4) The insolubility of the stearate of potash in alkaline solutions. 3 



(5) Insolubility of tallow, lard, &c., in petroleum ether of .69 specific 

 gravity. 4 



(6) The relative solubility of butter fats and substitutes therefor in a 

 mixture of 50 per cent, alcohol and 66 per cent, ether. 5 



1 Pharm. Rumlscli., 1886, p. 248. 



2 Kunstmann. Pharm. Ceutralh., 1875, No. 9. 

 :5 Gatehouse, Cbem. News, vol. 32, p. 297. 

 4 Zeit. Anal. Chem., 1872, p. 334. 



6 Hussou Zeit. Anal. Chem., 1880, p. 236; Filsiiiger, Pharm. Centralh., 1878, p. 260. 



