158 



Some figures obtained in the Maine laboratory are given in the following table, and 

 lead the writer to believe that good results can be obtained when the double-extrac- 

 tion method is carried out as follows: 



Prepare strips of soft white filter paper 4 by 24 inches of the quality of the S. & S. 

 No. 597, by soaking two or three hours in alcohol, then after thoroughly drying in the 

 oven extracting several hours with ether until no residue is left from the* ether as it 

 comes through. Then take 10 cc of a 20 per cent solution of the condensed milk and 

 distribute it carefully over the whole surface of the thoroughly dried paper. This is 

 best done by attaching one end of the paper to some object and holding the other end 

 out straight so that the pipette can be emptied by passing the point back and forth 

 over the whole surface. To dry the paper, suspend it over a copper wire in the drying 

 oven, where it will thoroughly dry out in two hours or much more .rapidly than if 

 coiled up or put in a tube. After drying roll up in a coil, wind with thread or small 

 copper wire, place in the extractor, and extract not less than eight hours. If it is the 

 sweetened product remove the coils from the extractor, loosen the wire or thread, dry 

 and suspend in 500 cc of water for two hours, then return the coils to the oven and dry 

 as before, and extract again for not less than five hours. Five cc of milk and a coil 4 

 by 12 inches may be used if preferred. 



Determination of fat in condensed milk by modifications of the double-extraction method. 



Modifications. 



Fat. 



5 cc (2 grams) of 40 per cent solution extracted 8 hours with ether: 



Per cent. 



Exhausted with water and extracted 5 hours more (average of 4 samples) 



Exhausted a second time and extracted a third time 8. 45 



cc (2 grams) of a 20 per cent solution on a coil 5 by 24 inches: 



10 Extracted 10 hours a 55 



Exhausted with water and extracted 5 hours more 8. 78 



cc (2 grams) of a 20 per cent solution on a coil 5 by 24 inches: 



Extracted 14 hours 8. 42 



Exhausted with water and extracted again 6 hours 8. 69 



5cc (1 gram) of a 20 per cent solution on a coil 5 by 12 inches: 



Extracted 5 hours a 45 



Exhausted with water and extracted 5 hours more : 8. 78 



5 cc (1 gram) of a 20 per cent solution on a coil 5 by 12 inches: 



Extracted 10 hours with ether & 36 



Exhausted with water and extracted again 8. 85 



10 cc (1 gram) of a 10 per cent solution on a coil 5 by 24 inches: 



Extracted with ether 14 hours 8. 42 



Exhausted with water and extracted 5 hours more 8. 95 



RECOMMENDATIONS. 



It is recommended that 



(1) The following methods be adopted as official methods: 



1. PREPARATION OF SAMPLE. 



Place the can, if cold, in water at 30 to 35 C. until warm. Open and mix thor- 

 oughly by transferring the contents of the can to s*ome dish sufficiently large to thor- 

 oughly stir and make the whole mass homogeneous. Care must be taken to scrape 

 out all milk adhering to the interior of the can. Weigh 100 grams into a 500 cc flask 

 and make up to the mark with water. If the milk will not completely dissolve, each 

 portion must be weighed out separately for analysis. 



2. TOTAL SOLIDS. 



Use 10 cc of the above 20 per cent solution and proceed as in the case of milk analysis 

 according to the method given in Bulletin 107, page 117, Method I, drying either on 

 sand or asbestos fiber. 



3. ASH. 



Ignite the residue from 10 cc of the 20 per cent solution at low red heat, leach with 

 hot water if sucrose is present, ignite the residue and filter until white, add the leach- 

 ings, evaporate to dry ness again in usual manner and weigh. 



